RECOVER CPR Basic life support Flashcards
1
Q
What is the cranial vena cava?
A
It drains deoxygenated blood from the brain and muscles (cranial part of the body) into the right side of the heart
2
Q
What is the right atrium?
A
This is a heart chamber that receives deoxygenated blood from the cranial and caudal vena cavae and coronary circulation.
3
Q
What valve sits between the right atrium and right ventricle?
A
Tricuspid valve
4
Q
How does blood move from the right atrium to the right ventricle?
A
Through atrial systole
5
Q
Where is the tricuspid valve located?
A
Between the right atrium and the right ventricle
6
Q
Is the tricuspid valve open or closed in ventricular diastole?
A
open - as blood enters from the atrium in to the ventricle
7
Q
What happens to the tricuspid valve during ventricular systole and why?
A
It closes to prevent backflow of blood from the ventricle to the atrium
8
Q
Where does blood flow to next from the right ventricle?
A
To the pulmonary artery
9
Q
Where is the pulmonic valve located?
A
Between the right ventricle and pulmonary artery
10
Q
What happens to the pulmonic valve in ventricular diastole and why?
A
It closes to prevent the back flow of blood from the pulmonary artery to the right ventricle
11
Q
What does the pulmonary artery do?
A
It carries deoxygenated blood from the right ventricle to the lungs so that it can pick up oxygen and off load carbon dioxide.
12
Q
What is the caudal vena cava?
A
It carries deoxygenated blood from the caudal part of the body to the right atrium of the heart. This includes kidney, liver, spleen, GI tract and muscles.
13
Q
What do pulmonary veins do?
A
They carry oxygenated blood from the lungs to the left atrium
14
Q
What is the left atrium?
A
It is a chamber on the left side of the heart that receives oxygenated blood from the lungs via the pulmonary veins.
15
Q
Where is the mitral valve located?
A
Between the left atrium and the left ventricle
16
Q
Is the mitral valve open or closed during atrial systole?
A
It is open to allowed blood flow in to the left ventricle
17
Q
What happens to the mitral valve in ventricular systole and why?
A
It closes to prevent back flow of blood in to the left atrium
18
Q
What is the left ventricle?
A
This receives oxygenated blood from the left atrium through the mitral valve
19
Q
Where is the aortic valve located?
A
Between the left ventricle and aorta
20
Q
What happens to the aortic valve during left ventricular diastole?
A
It closes to prevent backflow
21
Q
What does the aorta do?
A
Carries oxygenated blood from the left ventricles to the organs and tissues of the body where the oxygen can be used for energy production
22
Q
What side of the heart does blood enter?
A
Right side
23
Q
What side of the heart does the blood leave?
A
Left side
24
Q
What percentage of the blood flow is from passive and contraction of the atrium?
A
The majority of this flow (approximately 70%) is passive, with the remaining 30% occurring when the left atrium contracts.
25
What is ventricular relaxation called?
The period of left ventricular relaxation is called ventricular diastole.
26
What happens to the blood after the oxygen has been diffused in to the tissues for energy production?
Concurrently, carbon dioxide, a waste product of energy production in the tissues, diffuses into the capillaries to be carried back to the lungs for excretion.
27
What is diastole?
relaxation of a heart chamber
28
What is systole?
contraction of the heart chamber
29
What happened to the carbon dioxide waste product?
The blood moves from the pulmonary arteries into the smaller vessels, and ultimately to the pulmonary capillaries, where the carbon dioxide picked up from the tissues diffuses into the alveoli to be excreted when breathing out
30
Which chambers of the heart carry oxygenated blood?
The left atrium and left ventricle contain oxygenated blood. The left atrium receives oxygenated blood returning from the lungs and the left ventricle pumps oxygenated blood out to the systemic circulation, where it provides oxygen for metabolic processes in the tissues.
31
Which chamber contains the blood that is about to go out into the tissues of the body?
The left ventricle contains the oxygen-rich blood that is about to pumped through the aorta to the tissues of the body to deliver the oxygen needed for energy production.
32
What does the electrical conduction system of the heart activate?
The electrical conduction system of the heart activates the repeated cycle of relaxation and contraction of the atria and ventricles.
33
What is the sinoatrial node?
It is a collection of specialised cardiac muscles
34
Where is the sinoatrial node located?
right atrium
35
What is the role of the sinoatrial node?
to generate electrical impulses of the muscle cells around rather than to contract themselves
36
What cells in the heart have the highest intrinsic rate of activation and set the overall rate of contraction of the heart?
Sinoatrial node
37
What happens the sinoatrial node cells become activated?
They stimulate the cardiac muscle in the atria to contract and this conducts an electrical impulse to the atrioventricular node.
38
What is the atrioventricular node?
This is like the sinoatrial node and consists of specialised cardiac muscle cells
39
What is the role of the atrioventricular node?
The role is more for the conduction of impulses rather than contraction
It slows down the conduction initiated by the sinoatrial node to the ventricles
The slowing down of these impulses means that the duration of ventricular diastole is increased allowing for more blood to fill it within this time
40
What is the bundle of his?
A group of specialised cardiac muscle cells that focus on conduction rather than contraction.
They conduct the electrical impulses from the atrioventricular node serving the left and right ventricles for systole
41
What is the intraventricular septum?
The muscle tissues between the two ventricles
42
What are purkinje fibres?
They are specialised cardiac muscle cells that focus on conduction - these are an extension from the bundle of his and disperse in to the ventricles causing contraction
43
What triggers the beginning of the cardiac cycle?
The sinoatrial node
44
What do the electrical impulses from the sinoatrial node stimulate?
They stimulate the right and left atria causing them to contract in sync
45
What stimulates the atrioventricular node?
The contraction of the atria from the electrical impulses of the sinoatrial node
46
What stimulates the bundle of his?
The atrioventricular node introduces a slightly delayed conduction
47
Where do the electrical impulses travel to from the bundle of his?
From the bundle of His, the electrical impulses travel down the right and left bundle branches, which further divide into the Purkinje fibers that cause contraction of the ventricular myocardial cells in their respective ventricles.
48
Write in order the cardiac cycle
Activation of SA Node
Stimulation of right and then left atrium
Activation of the AV node
Stimulation of the Bundle of His and Purkinje fibers
Activation of the right and left bundle branches causing ventricular contraction
49
What is cardiac output?
is the amount of blood delivered to tissues of the body each minute.
50
What 2 variables determine cardiac output?
the stroke volume (SV) and the heart rate (HR)
51
what provides tissues with the fuel they need to maintain their metabolic functions?
The oxygen carried in blood
52
What is the stroke volume?
the amount of blood pumped during each contraction of the ventricle
53
What is the heart rate?
the heart rate is the number of times the ventricle contracts per minute.
54
How do you calculate cardiac output?
CO = SV x HR
| Cardiac output = stroke volume x heart rate
55
What 3 variables is stroke volume determined by?
preload, afterload and contractility
56
What is preload?
the amount of blood available to fill the left ventricle during diastole that can then be pumped out to the body during systole.
57
What is afterload?
the pressure against which the left ventricle has to push during systole, determined largely by the tone of the peripheral blood vessels.
58
What is contractility?
the strength with which the ventricle contracts during systole
59
What is the normal stroke volume?
Normal stroke volume is about 1-2mL/kg
60
In a normal dog what is the estimated cardiac output?
CO is 100 mL/kg/min
61
In a 20kg dog what should the cardiac output be?
CO should be 2 L/min
62
What would the normal stroke volume be in a 20kg dog?
Normal stroke volume is 20-40 mL
63
What is cardiopulmonary arrest?
when the heart of the animal stops beating and the animal stops breathing.
64
What are the 4 primary types of dysfunction that can lead to cardiac arrest?
Asystole
Pulseless electric activity (PEA)
Ventricular fibrillation (VF)
Pulseless ventricular tachycardia (pVT)
65
What is asystole?
Asystole is the complete cessation of electrical and mechanical heart activity
66
What is pulseless electrical activity?
Pulseless electrical activity (PEA) occurs when there is no effective mechanical activity in the heart, which may be more commonly observed (if one would look with echo or the like) than complete myocardial standstill
67
What is ventricular fibrillation?
Ventricular fibrillation (VF) occurs when there is aberrant, uncoordinated mechanical activity of the muscle cells in the ventricles, leading to “quivering” mechanical activity. Because this mechanical activity is ineffective, no forward flow of blood out of the heart occurs. Both ventricles will be quivering and out of sync. There is no effective contraction of the heart and the ventricles look like a bag of worms.
Watch the video to see a normal heart rhythm (sinus rhythm), which then changes to VF. Note that the ECG shows random, irregular electrical activity, and although the heart is moving, there is no coordinated contraction, and the heart is quivering.
68
What is pulseless ventricular tachycradia?
Pulseless ventricular tachycardia (pulseless VT) occurs when there are very rapid, ineffective ventricular contractions. These contractions are driven by a focus of abnormal ventricular myocardial cells rather than from the normal conduction system we just explained. Because these contractions are so fast, there is no time for filling of the ventricles, and therefore no forward flow of blood out of the heart.
Watch the video to see a normal heart rhythm (sinus rhythm), which then changes to pulseless VT. Note that the ECG shows regular, repeated electrical activity, and the ventricles are contracting in a coordinated fashion, but the rate of contraction is very fast.
69
What side of the heart does blood return to with Co2?
Blood returns from the body to the right side and is pumped to the lungs to remove CO2 and pick up O2
70
What are the four main types of cardiac rhythms?
```
Four main types of cardiac rhythms
Asystole
Pulseless electrical activity (PEA)
Ventricular fibrillation (VF)
Pulseless ventricular tachycardia (pVT)
```
71
What is the primary goal of cardiopulmonary resuscitation?
The primary goal of CPR is to restore the flow of red blood cells (RBCs) through the circulation in patients with cardiopulmonary arrest.
72
Why must the red blood cells travel around the body?
The RBCs must travel to the lungs to pick up O2 and deliver CO2 from the tissues for excretion from the lungs. Then, they must travel to the tissues to deliver O2 for cell metabolism and pick up CO2, the main waste product of metabolism
73
What must a rescuer do to an animal in cardopulonary arresr and why?
In patients with CPA, the heart is not beating spontaneously, and the rescuer works to facilitate blood flow using chest compressions and ventilation to replace these vital functions of the circulation
74
What happens to red blood cells when it enters the right side of the heart?
Red blood cells returning from the tissues are low in oxygen and high in carbon dioxide. They enter the right atrium and are pumped into the right ventricle. From the right ventricle, they are delivered to the pulmonary artery (PA)
75
What happens to the red blood cells in the pulmonary arterial system? what exchange of gases occur?
The pulmonary arterial system divides into smaller and smaller arterioles, and then finally into the pulmonary capillaries, which pass by the small air-filled alveoli. Carbon dioxide diffuses out of the red cells into the alveoli, and oxygen diffuses from the alveoli into the red cells down their respective concentration gradients.
76
What happens to gases in the pulmonary system?
Pulmonary:
Excrete CO2 produced in the tissues
Pick up O2 for delivery to the tissues
77
What happens to gases in the tissues?
Tissues:
Pick up CO2 produced in the tissues
Deliver O2 for cellular energy production
78
Where does air enter through on the dog and cat?
Air enters via the mouth or nares, Dogs and cats primarily breathe through the nose (with air entering via the nares)
79
When do dogs and cats convert to mouth breathing?
Dogs commonly convert to mouth breathing when exercising or hyperthermic; cats, on the other hand, rarely breathe through the mouth, even if the nares or nasal passages are obstructed.
80
Where does air flow from the nares?
nasopharynx
81
Where does air flow from the mouth?
The mouth to the oropharynx
82
Where does air flow from after passing the nasopharynx and oropharynx?
From the nasopharynx and oropharynx, the air moves through the larynx and into the trachea.
83
Where does the trachea bifurcate to?
The trachea bifurcates into the mainstem bronchi
84
What does the bronchi divide into?
Bronchi further divide into bronchioles and terminal airways.
85
What is alveoli and what is their function?
small sacs with very thin membranes separating them from the pulmonary capillaries.
This thin separation facilitates the movement of oxygen from the alveoli to the blood and carbon dioxide from the blood into the alveoli for excretion
86
The two main functions of the respiratory system are ventilation and oxygenation. What is the primary goal of ventilation?
The two functions of the respiratory system are largely independent of each other. The term ventilation is used to describe the bulk movement of air into and out of the alveoli, and the primary goal of this process is excreting carbon dioxide. Oxygenation refers to the ability for oxygen in the alveoli to diffuse into the blood, and is largely dependent on the health of the alveoli and the lung parenchyma in general
87
What movement does diaphragm contraction cause?
Diaphragm contraction causes the diaphragm to move away from the chest and towards the abdominal organs.
88
What movement does intercostal muscle contraction cause?
External intercostal muscle contraction causes outward movement of the chest.
89
What happens to the pleural space when the chest cavity volume increase?
Chest cavity volume increases and a negative (sub-atmospheric) pressure begins to generate in the pleural space between the chest wall/diaphragm and the lungs.
90
What movement does the negative pressure in the pleural space cause?
The negative pressure in the pleural space causes the external surface of the lungs to be pulled outward, creating a negative (subatmospheric) pressure within the alveoli and the airways
91
What effect does negative pressure have on the alveoli?
The negative pressure causes the alveoli to expand and pull in fresh air.
92
What effect does exhalation have on the intercostal muscles and diaphragm?
Exhalation is passive and is initiated when the intercostal muscles and diaphragm relax. The elastic properties of the chest cause it to recoil back to pre-inhalation size.
93
What effect does exhalation have on the alveoli?
The compression of the alveoli forces out alveolar air. The air in the alveoli, containing large amounts of CO2 from the tissues, is expelled, and CO2 is excreted.
94
What is minute ventilation?
It is the amount of air that moves in and out of the respiratory system in one minute.
95
How do you calculate the minute ventilation?
Minute Ventilation = (Tidal Volume) x (Respiratory Rate)
96
What is the tidal volume?
Tidal volume is the amount of air that moves in or out of the lungs with each respiratory cycle
97
What does the amount of carbon dioxide in arterial blood tell you?
Because the amount of carbon dioxide removed from the alveolus is proportional to minute ventilation, the amount of carbon dioxide in the arterial blood (which is the blood that has completed all gas exchange in the lungs) is inversely proportional to minute ventilation.
98
What is the arterial carbon dioxide reference range?
Arterial carbon dioxide is maintained within a narrow range (approximately 35-45 mmHg, although there are species differences) by sensors in the brain and in the periphery.
99
What does the body do when Carbon dioxide levels rise in arterial blood?
When carbon dioxide concentrations in the arterial blood rise, the sensors in the brain and the periphery stimulate the brain to increase minute ventilation (via increases in respiratory rate, tidal volume, or both). This results in increased excretion of CO2, returning CO2 concentrations to the normal range.
100
What does the body do when arterial carbon dioxide falls?
When carbon dioxide concentrations fall, the sensors in the brain and periphery signal the brain to reduce minute ventilation, reducing excretion of CO2. This returns CO2 concentrations in the arterial blood to the normal range.
101
What pressure of oxygen does venous blood have?
approximately 40 mmHg or less
102
What pressure of oxygen does the alveolus pulmonary capillary blood have?
the alveolus has a much higher partial pressure of oxygen than venous blood (approximately 100 mmHg
103
What two parts are respiratory function compromised of?
Respiratory function is comprised of two parts: ventilation and oxygenation.
Ventilation (removal of carbon dioxide)
Oxygenation (diffusion of oxygen into blood)
104
What are the main gases involved on inhalation?
During inhalation, fresh gas containing oxygen and nitrogen are brought into the alveolus. This gas has a large amount of oxygen and nitrogen, but effectively no CO2.
105
What happens to the alveolus on exhalation?
As the chest wall recoils, the alveolus is compressed and the alveolar gas, now containing large amounts of CO2 that has diffused from the blood into the alveolus, is excreted from the body.
106
What drives the movement of oxygen from the alveolus into the blood?
The movement of oxygen from the alveolus into the blood is driven by the concentration gradient between the alveolus and the capillary blood.
107
Is the following statement true or false?
At the end of exhalation, the exhaled air has lower carbon dioxide than the environmental air.
Room air contains almost no carbon dioxide. At the end of exhalation, the exhaled air has higher carbon dioxide, generated by energy production in the tissues and delivered to the alveoli by the circulation.
108
What are the basic functions of the circulation of blood ?
deliver oxygen to the tissues
| remove carbon dioxide, the primary waste product of energy production, from the tissues.
109
Which valve prevents backward flow of blood into the left atrium when the left ventricle contracts?
Mitral
110
Which vessel carries deoxygenated blood from the brain back to the right side of the heart?
Cranial vena cava
111
What does ABC represent?
Airway - rule out obstruction of the airway
Breathing - determine if the patient is breathing or not
Circulation - determine if the patient has blood flow to the tissues
112
Why is it important to check the airway of a patient that may be in cardiac arrest?
If the patient does not have a patent airway, CPR will not be successful. Therefore, it's important that the airway is examined thoroughly but quickly to identify and address any obstructions. The airway exam should only be done in unresponsive patients. If the patient responds, the exam should be immediately halted and a full primary survey initiated to evaluate respiratory, cardiovascular, neurologic and perfusion status of the patient.
113
How do you check the breathing when assessing whether to perform CPR? What should you do if you are unsure if the animal is breathing or not?
If the airway is clear, the next step is to determine if the patient is breathing. This can be accomplished by looking for chest excursions or gently laying a hand on the chest and feeling for movement. If the rescuer is unable to definitively determine that breathing is occuring within a few seconds, it should be assumed that the patient is apneic and CPR should be initiated.
114
How do you check for an animals circulation if they are in cardiac arrest? What issues could you have with this?
Traditionally, circulation has been evaluated as part of the initial assessment of an unresponsive patient. Common methods are palpation of femoral or dorsal metatarsal pulses, palpation of an apex beat, or auscultation of the heart. However, several studies have shown that in up to 35% of pulseless cases, the rescuer believes he or she feels a pulse. Therefore, it is no longer recommended that pulses be checked in apneic patients, and CPR should be started immediately. If the circulation is assessed, it is imperative that no more than 10-15 seconds be spent on the complete ABC assessment. Delays in initiation of Basic Life Support are uniformly associated with worse outcomes in patients with CPA.
115
What steps should you take when realising an animal is apnoeic?
Effective CPR requires a team
Immediately call for help if you are faced with an unresponsive patient, in case CPR is needed.
Do your AB (+/-C) assessment
If the patient is apneic, start BLS. If the patient is not apneic, move on to your primary survey and identify any imminently life-threatening issues. If after a 10-15 second assessment you're not sure if the patient is in CPA, you should start BLS. The risks of starting CPR in a patient that has not arrested are much less than the risks of not starting CPR in a patient that has arrested.
116
How can you explain to an owner that CPR needs to be performed on their pet?
Be compassionate but direct about the need to make that decision as soon as possible, and inform them that any delays in starting CPR reduce the chance of a successful outcome. You likely won’t be able to determine the cause of the arrest until after the patient is resuscitated and you can do additional diagnostics.
117
What are the risks of CPR? and how do you explain this to an owner?
A small number of studies evaluating the risk of starting chest compressions in patients not in CPA have shown a low incidence of significant complications, including:
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Rib fractures (1.6%)
Muscle damage (1.4%)
Chest pain (11.7%)
Given the low risk of CPR and the universally fatal nature of CPA, it’s best to quickly explain that studies have shown a very small risk of non-life threatening injuries from CPR, but that the he only option for trying to stabilize the patient is to do CPR as soon a possible.
```
118
What are the chances of survival after CPR?
Survival to discharge of dogs and cats with CPA treated with CPR is dependent upon the underlying disease process that lead to the arrest. Arrests due to peri-anesthetic drug reactions or treatable underlying disease have survival to discharge rates of up to 50%, but overall survival to discharge is approximately 6-7% for dogs and cats. If the cause of the arrest is likely an acute, reversible problem such as a drug reaction, inform the owner that the pet likely has a 50-50 chance of survival. If you’re unsure of the cause, or the patient has a progressive disease that likely led to the arrest, it’s best to be reasonable and let the owner know that the chances of survival are low, but if they want to give the pet a chance, you have to start CPR as soon as possible. Seconds count.
119
How long should obtaining a focused history and ABC assessment take?
A focused history should be obtained at the same time the ABC assessment is being done. When done in combination with an ABC assessment, this should take no more than 20-30 seconds. As discussed previously, the ABC assessment alone should take no longer than 10-15 seconds
120
What information is important to get from the owner when gaining a focused history?
Any recent issues noted by the owner may be helpful in determining the cause of the arrest and affect initial treatment. Keep the owner focused on recent issues that may have precipitated the arrest rather than chronic issues that are less likely to be relevant. Prompt about anything out of the ordinary that could lead to instability like gastrointestinal, respiratory or neurologic signs. Identification of the underlying cause of the arrest can provide critical information that may affect treatment both during CPR and in the post-cardiac arrest period. The full medical history should be obtained once the crisis has been addressed.
121
What are the three tiered resuscitation codes?
A three-tiered system is generally used to denote resuscitation codes
Red code = Do not resuscitate
Yellow code = Closed chest CPR
Green code = Open chest CPR
122
How do you support if they are choosing not to resuscitate their pet?
Many clients are uncomfortable with the idea of “doing nothing” if a pet experiences CPA. It’s important to help your client to make the best decision for the individual pet, and to reassure your client that you will support whatever decision is made. For patients with irreversible, progressive diseases with high mortality rates or significant co-morbidities, a red code is likely the best option given the low likelihood that CPR will be successful if CPA occurs. However, some clients need to feel that everything possible was done in the event of an acute crisis. Explaining the prognosis for the individual patient and clearly stating that you will support your client’s decision will make this difficult choice somewhat easier for the client.
123
How do you explain to an owner what closed CPR is?
Small to medium sized dogs, large dogs with deep, narrow chests (i.e., keel-chested dogs) and cats are good candidates for closed chest CPR. A brief explanation of the procedure is warranted, including the fact that a tube will be placed into the airway to facilitate breathing, the chest will be compressed to generate blood flow to the organs, and drugs will be administered to improve circulation. Many clients are familiar with the concept of closed chest CPR, and so a brief explanation of the procedure and an opportunity for them to ask additional questions are usually sufficient.
124
How do you explain to an owner what open CPR is? When would this be indicated?
Open chest CPR should only be offered if post-arrest care is available either in your practice or at a local referral center. It’s also important to explain to clients the invasive nature of the procedure, and to apprise them of the cost of this procedure at your practice, including the costs of aftercare.
Numerous studies have shown that open chest CPR generates better blood flow and is associated with increased survival compared to closed chest CPR. Therefore, if a client chooses open chest CPR, it should be initiated as soon as possible after CPA has been diagnosed, as any delay reduces the chance of a successful outcome. The technique for open chest CPR is described in detail in the CPR: Advanced Life Support course.
Indications for open chest CPR include:
Large or giant breed round-chested dogs
Pleural space disease
Pericardial disease
Patients in which closed chest CPR has been unsuccessful
Patients in surgery
Open chest CPR is generally contraindicated in small dogs (less than 10kg) and cats unless the patients are already under anesthesia and in surgery because of the small size of the chest cavity and the difficulty associated with cardiac massage in these smaller patients.
125
What will failure to identify an airway obstruction lead to?
Airway obstruction will prevent effective ventilation and delivery of oxygen to the tissues, and failure to identify obstruction is likely to lead to unsuccessful resuscitation.
126
How do you perform an airway assessment and how long should this take?
The airway assessment should take no more than 5 seconds and it usually involves simply visually inspecting the airway. However, if visualization of the airway is compromised, you may need to clear the airway or remove foreign objects obstructing the airway.
First open the mouth and pull out the tongue so that you can visually inspect the airway all the way back to the larynx. If the dog responds in any way, stop immediately to avoid being bitten. First open the mouth and pull out the tongue so that you can visually inspect the airway all the way back to the larynx. If the dog responds in any way, stop immediately to avoid being bitten. Careful digital palpation from the oral cavity back to the laryngeal area may reveal foreign objects, masses, or swellings causing airway obstruction. If the airway is clear, continue to the breathing assessment. If the airway is obstructed, clear the obstruction. It is crucial that digital palpation be gentle and that foreign objects in the larynx not be pushed further back into the airway. If the patient is rousable and will not tolerate palpation, digital palpation should be halted and the patient assessed for abnormal breathing sounds associated with airway obstruction.
127
What Three types of evaluations can be performed to assess patients with no visible evidence of chest excursions? How long should this assessment take?
Lightly touch the chest
If there are no obvious chest excursions on initial visual inspection, breathing can be further assessed by lightly touching the chest and feeling for chest movements.
Auscult the chest
Breathing can also be assessed by auscultation of the chest for lung sounds.
Cotton or slide
Breathing can be further assessed by placing cotton or a slide in front of the nares and looking for movement or fogging, respectively.
These evaluations must be done quickly. No more than 5 to 10 seconds should be spent on the breathing evaluation.
128
What does agonal breathing signify?
Agonal breathing, or gasping, should not be confused with normal spontaneous respiration, as this type of breathing is generally associated with cardiac arrest. Patients will be unresponsive and often have fixed and dilated pupils.
Although it does not provide adequate ventilation, agonal breathing is considered a positive sign in patients with CPA, as it suggests that the respiratory centers in the brainstem are still functioning and have not likely been deprived of perfusion for an excessive period of time.
Agonal Breathing
Gasping breaths
Signs of CPA
No effective ventilation
129
How do you assess the circulation? How long should this take?
Rapid assessment of the circulation may be undertaken as part of the ABC assessment, but should take no longer than 5-10 seconds and should not prolong the ABC assessment to more than 15 seconds in total. If any doubt exists about the presence of a pulse in an apneic or agonal patient, CPR should be initiated immediately rather than pursuing further diagnostic assessment of the circulation. It is worth noting that even if a patient is apneic and still has a pulse, it is highly likely that the patient will progress to CPA quickly due to the rapid development of tissue hypoxia. For this reason, rather than taking time to do a circulation assessment in the apneic patient, current guidelines recommend initiating CPR in unresponsive, apneic patients without taking the time to assess the circulation.
Due to the low likelihood of significant injury from CPR, current veterinary and human CPR guidelines do not recommend pulse palpation before starting CPR in patients that are unresponsive and not breathing.
130
When should assessing the circulation in ABC be skipped?
In patients that are unresponsive and not breathing, current veterinary guidelines recommend skipping the assessment entirely and starting CPR immediately. If a circulation assessment is done, it should take no more than 5 to 10 seconds.
131
What 4 different ways can you check the circulation in large dogs?
Checking the dorsal pedal pulse
The dorsal pedal artery runs over the medial aspect of the tarsus and is palpable in most dogs with a minimal mean arterial blood pressure of 60 mm Hg. If no dorsal pedal pulse is palpated, it is recommended that an additional circulation assessment be performed to confirm pulselessness in case the patient is hypotensive.
Checking femoral pulse
The femoral pulse is palpable in the inguinal (groin) region and can generally be felt even in patients with low blood pressure.
It may be difficult to find this pulse in obese patients.
Palpating the heart
In non-obese, keel-chested larger breed dogs, such as Greyhounds, Viszlas, and Doberman Pinschers, the beating heart may be palpable on the chest at the 4th to 6th intercostal spaces on the lower 1/3 of the chest. The optimal site can be identified by pulling the elbow caudally to the level of the costochondral junction. The apex beat is more difficult to palpate in non–keel-chested larger breed dogs.
Auscultating the heart
A spontaneously beating heart will usually generate sounds loud enough to hear with a stethoscope. A pulse should be palpated even if a heart beat is heard on auscultation, as unresponsive, apneic patients with cardiac contractility too poor to generate blood flow sufficient to produce palpable pulses may still require chest compressions. Possible causes of pulselessness in an animal with an auscultable heart beat include the following:
Markedly decreased cardiac contractility, which may require chest compressions
Severe shock
Pericardial effusion with tamponade
Severe pleural space disease
132
What part of the circulation would you not check on a small cat or dog and why?
In cats and small dogs, palpation of the apex beat or auscultation is more likely to be successful than pulse palpation due to the small size of the peripheral arteries and their highly compliant and narrower chests, which make palpation of the apex beat and auscultation easier than in larger dogs
133
How do you do a rapid evaluation of an unresponsive patient?
Diagnosis of CPA
History-taking
Talking to owners about resuscitation codes
134
How do you briefly carry out an airway assessment?
Airway assessment
Visual inspection
Clearing the oropharynx
Digital palpation
135
How do you briefly carry out a breathing assessment?
Breathing assessment
Lightly touch the chest
Auscult the chest
Place cotton or slide in front of the nares
136
How do you briefly carry out a circulation assessment?
Circulation assessment
Remember that circulation assessment is no longer recommended in unresponsive patients, but if you choose to assess the circulation, it should not prolong the total ABC assessment to more than 15 seconds. Options for assessing the circulation in unresponsive cats and small dogs:
Palpation of the apex beat
Auscultation of the heart
Palpation of the femoral pulse
137
What are the goals of chest compression?
The goals of chest compressions are to replace the functions of the left and right ventricles, provide blood flow to the lungs for gas exchange, and deliver oxygen to the tissues for energy production.
138
What percentage of normal cardiac output does well executed chest compressions produce?
It has been shown experimentally that even well-executed external chest compressions produce only 30% of normal cardiac output, and that poorly performed compressions generate even lower cardiac output.
139
How can chest compressions facilitate blood flow?
There are two competing theories regarding how external chest compressions can facilitate this flow of blood:
Thoracic pump theory
Cardiac pump theory
140
Which of the following are the primary goals of chest compressions?
The primary goals of performing chest compressions are to replace the function of the left and right ventricles, to provide blood flow to the lungs, and to oxygenate the tissues.
141
How does direct compression of the heart pump blood around the body?
Direct compression increases the pressure in the ventricles, closing the mitral and tricuspid valves, preventing backflow of blood from the ventricles into the atria. The increased pressure in the ventricles also opens the pulmonic and aortic valves, providing blood flow to the lungs and the tissues respectively.
Elastic recoil of the chest and heart between compressions creates negative pressure within the heart, allowing filling of the ventricles before the next compression.
142
What is the thoracic pump theory?
It is based on the concept that external chest compressions raise overall intrathoracic pressure and push blood from the aorta into the systemic circulation.
Recoil of the chest between compressions causes negative pressure within the thorax, drawing blood into the cranial and caudal venae cavae and into the heart. Blood is also drawn into the pulmonary vessels during this recoil phase due to expansion of the highly compliant pulmonary vessels.
In the thoracic pump model, the heart acts as a conduit for movement of the blood rather than as a pump. The mitral and tricuspid valves do not close during chest compressions and blood flows passively through the heart.
During compressions, the stiff, muscular aorta is partially compressed within the thorax, resulting in higher pressures developing in this system, allowing establishment of the arteriovenous pressure gradient required for forward flow to provide oxygenated blood to the tissues. The thin-walled, highly compressible cranial and caudal venae cavae and pulmonary vessels are collapsed, preventing backflow of blood though the venous system and into the lungs. In addition, the presence of valves in the extrathoracic veins prevents retrograde flow during compressions.
Elastic recoil of the chest between compressions causes negative pressure within the thorax, drawing blood into the cranial and caudal venae cavae and into the heart. Blood is also drawn into the lungs during this recoil phase due to expansion of the highly compliant pulmonary vessels. The thoracic pump model describes the heart as a passive conduit. The mitral and tricuspid valves do not close during chest compressions, and blood flows passively through the heart.
143
Which theory, cardiac pump or thoracic pump, is consistent with the following statement?
Low compliance of the aorta results in blood flow out of the thorax during chest compressions due to increased aortic pressure.
Cardiac pump theory or thoracic pump?
The thoracic pump theory states that the low compliance of the aorta allows it to be compressed but not collapsed by high intrathoracic pressure during chest compressions, causing increased aortic pressures and flow of blood out of the chest. The aortic valve prevents backflow of blood during compressions. In the cardiac pump theory, chest compressions directly compress the left ventricle, causing pressure to increase in the aorta due to increased blood flow out the aortic valve from the increased left ventricular pressure.
144
Which theory, cardiac pump or thoracic pump, is consistent with the following statement?
Backflow of blood is prevented by compression of the highly compliant cranial and caudal venae cavae
The thoracic pump theory states that an overall increase in intrathoracic pressure compresses the vena cavae, preventing backflow of blood into the venous system. The cardiac pump theory states that compression of the chest directly compresses the left and right ventricles, increasing pressure in the ventricles and closing the mitral and tricuspid valves. It is closure of the valves that prevents backflow in this model.
145
Which theory, cardiac pump or thoracic pump, is consistent with the following statement?
The major determinant of forward flow of blood to the tissues is an overall increase in intrathoracic pressure, so the chest compression technique should be focused on maximally compressing the chest.
The thoracic pump theory states that an overall increase in intrathoracic pressure secondarily compresses the aorta and left ventricle, leading to flow of oxygenated blood to the tissues. Chest compressions should be focused on maximally compressing the chest rather than on directly compressing the heart.
146
Which theory, cardiac pump or thoracic pump, is consistent with the following statement?
Blood flows to the lungs during elastic recoil of the chest.
The thoracic pump theory states that blood flows to the lungs during elastic recoil of the chest when negative intrathoracic pressure causes negative pressure within the highly compliant pulmonary vasculature. By contrast, the cardiac pump theory states that the during chest compressions, both the right and left ventricles are directly compressed, increasing ventricular pressures and opening the aortic and pulmonic valves, allowing blood flow to the tissues of the body and the lungs respectively.
147
Give a brief summary on the cardiac pump theory:
Cardiac Pump Theory
During compression, the left and right ventricles are directly compressed, delivering blood to the tissues of the body and to the lungs.
During elastic recoil of the chest, blood is drawn back into the left and right ventricles.
This technique is most likely to be successful in keel-chested medium and large breed dogs or in cats and small dogs.
148
Give a brief summary on the thoracic pump theory?
Thoracic Pump Theory
During external chest compression, overall intrathoracic pressure increases and pushes blood from the aorta out to the tissues of the body.
During elastic recoil of the chest, blood is drawn back into the heart and lungs.
This technique is most likely to be successful in round-chested medium and large breed dogs.
149
What is the ideal position for the patient when performing CPR?
Chest compressions should be done in lateral recumbency in most dogs and cats. There is experimental evidence that this position results in superior arterial pressures than those obtained by compressions in dorsal recumbency
150
How deep should chest compressions be performed during CPR? and how do you check this?
Compression depth should be targeted at 1/3 to 1/2 the width of the chest. Shallower compressions result in poor blood flow to the tissues. It may be difficult for the compressor to judge compression depth, so other members of the team should watch the chest compressions and provide feedback to the compressor if the depth seems incorrect. In medium and large breed dogs, it takes a large amount of force to obtain an effective compression. In smaller dogs and cats, it is possible to over-compress the chest, leading to myocardial contusion and other chest trauma.
151
At what rate should chest compressions be performed during CPR?
Regardless of the size of the patient, chest compressions should be done at a rate of 100 to 120 compressions per minute. Because cardiac output is the product of heart rate times stroke volume, lower compression rates result in reduced cardiac output, leading to lower survival rates. This reduced cardiac output is exacerbated by the fact that stroke volumes generated by good quality external chest compressions are only approximately 30% of normal stroke volume. Higher compression rates also reduce cardiac output because they do not allow for full elastic recoil of the chest, reducing return of blood to the heart and decreasing cardiac output. Singing a song in your head with the correct tempo, such as the Bee Gees’ “Staying Alive” can help you maintain the correct compression rate
152
Why is it important to allow chest recoil in CPR?
Between each chest compression, full elastic recoil of the chest must be allowed, so leaning or residual compression of the chest between compressions must be avoided. Leaning on the patient’s chest between chest compressions results in reduced return of blood to the heart and reduced cardiac output
153
How long should compression cycles per person when performing CPR?
Chest compressions should be done in cycles of 2 minutes without interruption. It takes approximately 1 minute of chest compressions for aortic blood pressure to reach a steady state level that provides perfusion to the heart and tissues. Shorter cycles of chest compressions reduce perfusion because that steady state pressure is not achieved or maintained for the necessary period of time. After each 2 minute cycle of compressions, a new compressor should take over to reduce fatigue and propensity to lean during compressions, which might prevent full elastic recoil of the chest.
154
What is the ideal position for the person performing CPR?
shoulder above elbows
engage with the core muscles
elbows locked in to position
one hand on top of the other with fingers locked and the heel of the hand over the other for stronger compressions
155
Compression depth should be targeted at 1/4 the width of the chest - true or false
false
Compression depth should be targeted at 1/3 to 1/2 the width of the chest. Inadequate depth of compression decreases stroke volume significantly and results in reduced blood flow to the tissues, resulting in worsened tissue hypoxia and poorer outcomes. Push hard!
156
Chest compressions in dogs should be done at a rate of 100 to 120 compressions per minute. - true or false
True
Chest compressions should be done at a rate of 100 to 120 compressions per minute. Slower compression rates reduce cardiac output, worsening tissue hypoxia and resulting in poorer outcomes. Push fast
157
Because of their higher heart rates, compressions in cats should be done at a rate of 160 to 180 compressions per minute. true or false
Experimental studies do not support the use of higher heart rate in smaller patients. Due to the lower cardiac output achieved during CPR, adequate time must be allowed for refill of the heart before the next compression, and higher rates are not recommended in smaller animals.
158
Chest compressions should be done in most dogs and cats in dorsal recumbency (with animals lying on their backs). true or false
false
Experimental work suggests that lateral chest compressions produce higher aortic pressures than compressions done in dorsal recumbency. Therefore, it is recommended that chest compressions be done in lateral recumbency in most small animal veterinary patients.
159
Chest compressions should be done in cycles of 5 minutes without interruption. True or false?
False
Chest compressions should be done in cycles of 2 minutes without interruption. This reduces fatigue in the compressor, allowing maintenance of good quality chest compressions and preventing leaning, which can reduce refilling and compromise cardiac output.
160
What is the most common type of chest conformation?
Many medium and large breed dogs have a round-chested conformation. These dogs have chests that are approximately as wide as they are deep, as you can see in this hound dog. When cut in cross section, the chest approximates a circle.
161
How can you confirm if a patient has a round chested conformation?
When round-chested dogs are in lateral recumbency, the chest has the appearance of a dome, rising to its highest point in the middle, as shown in the image here. When deciding if an unresponsive dog in lateral recumbency has a round-chested conformation, run your hand over the chest and feel for the dome shape
162
Where should you do chest compressions in a round chested animal?
If you determine that the patient has a round-chested conformation, chest compressions should be done to maximize blood flow using the thoracic pump theory. As shown in the image below, chest compressions are done in round-chested dogs over the widest portion of the chest (green arrow), not directly over the heart (red arrow). The heel of the hand in contact with the chest should be placed at the peak of the dome.
163
What is a keel chest?
Keel-Chest Conformation
Some medium and large breed dogs have a keel-chested conformation. These dogs have chests that are significantly deeper than they are wide, as you can see in this greyhound. When cut in cross section, the chest approximates a triangle.
164
How do you determine if a patient is keel chested?
When keel-chested dogs are in lateral recumbency, the chest has the appearance of a slope, gradually rising from the sternum ventrally to the spine dorsally. When deciding if an unresponsive dog in lateral recumbency has a keel-chested conformation, run your hand over the chest and feel for the slope shape.
165
How do you give chest compressions in a keel chested dog?
If you determine that the patient has a keel-chested conformation, chest compressions should be done to maximize blood flow using the cardiac pump theory. As shown in the image below, chest compressions are done in keel-chested dogs directly over the heart. The heel of the hand in contact with the chest should be placed 1/3 of the distance from the sternum to the spine, as shown in the image to the left.
166
What is considered a flat chest dog? How do you determine this?
Some dogs, especially brachycephalic breeds like the English Bulldog pictured here, have very shallow chests that are wider than they are deep. This chest shape is similar to the conformation of a human chest.
Because these dogs have wide, shallow chests, when in lateral recumbency (as pictured here) the dorsal and ventral chest walls (red) act as struts, making the chest stiff when attempting compressions on the lateral chest wall,
167
What is the most effective position for a flat chested dog to be in when receiving CPR?
In dogs with this flat-chested conformation, more effective chest compressions may be attainable when they are placed in dorsal recumbency.
Placing flat-chested dogs in dorsal recumbency may allow more effective compression of the thorax by concentrating the compressions on the surface of the widest portion of the chest (yellow), farthest from the struts formed by the shorter lateral chest wall segments (red). This allows the heart to be compressed between the sternum and the spine, employing the cardiac pump approach to chest compressions.
168
What type of chest conformation do small dogs and cats generally have?
Cats and small dogs generally have a keel-chested conformation, and the cardiac pump approach to chest compressions is usually recommended.
169
What is the best way to apply chest compression in small dogs and cats?
In obese cats and small dogs, the chest is likely to be stiffer. The two-handed approach to chest compressions as described below may be more efficacious in these patients. In addition, compressions over the widest part of the chest to employ the thoracic pump theory may be considered in some cases.
170
How do you find the location of the heart?
Finding the Location of the Heart
To quickly identify the location of the heart, pull the elbow caudally to approximately 1/3 the dorsal-ventral distance from the sternum to the spine. This will be at approximately the 4th to 6th intercostal space, directly over the heart. The same technique works in dogs.
171
What are the basic principles for chest compressions?
Compressions depth should be targeted at 1/3 to 1/2 the width of the chest.
Chest compressions should be done at a rate of 100 to 120 compressions per minute.
Between each chest compression, full elastic recoil of the chest must be allowed.
Chest compressions should be done in cycles of 2 minutes without interruption.
After each 2 minute cycle of compressions, a new compressor should take over.
172
Briefly what type of pump should keel chested, round-chested and flat-chested dogs receive?
Cardiac pump approach in keel-chested dogs
Thoracic pump approach in round-chested dogs
Sternal compressions in dorsal recumbency in flat-chested dogs
173
Briefly summarise the type of chest compressions small dogs and cats should receive?
Cardiac pump approach in most patients
One-handed or two-handed technique
Consider thoracic pump approach in obese patients
174
What is the general approach to chest compressions?
Do in lateral recumbency in most dogs and cats
Compression depth: 1/3 to 1/2 the width of the chest
Rate: 100 to 120 compressions per minute
Allow full elastic recoil of the chest between each compression.
Do in cycles of 2 minutes without interruption
Rotate compressors after each 2-minute cycle
175
What are the different chest conformations that need to be considered when performing chest compressions?
```
Medium and large breed dogs
Keel-chested dogs
Flat-chested dogs
Small dogs and cats
Obese small dogs and cats
```
176
Max is a 120-pound Rottweiler.
Max presented to Dr. Williams’s clinic to be neutered. As Max was being induced for anesthesia, the anesthetist noted that he stopped breathing on his own. An ABC assessment showed that his airway was clear, but he had no pulse.
Dr. Williams decides to initiate Basic Life Support.
How should Max be positioned when performing chest compressions?
lateral recumbency
177
Well executed chest compressions produce approximately ___% of a normal stroke volume
30%
178
According to the cardiac pump theory of chest compressions, blood flow is accomplished by direct compression of the ventricles, opening the aortic and pulmonic valves and allowing blood flow to the lungs and the tissues of the body. True or false?
True
179
In most cats, the thoracic pump theory likely predominates, so chest compressions should be done over the widest portion of the chest. True or false?
False
180
What are the two options for ventilation in CPR?
Endotracheal intubation
Mouth-to-snout breathing
If endotracheal intubation is feasible, it is the preferred method of ventilation during CPR. Mouth-to-snout ventilation should only be used when supplies to intubate are not readily available, or in the case of single rescuer CPR. As soon as intubation supplies are available and/or a second rescuer arrives, all patients should be intubated and ventilated with positive pressure ventilation
181
What is the most effective ventilation method during CPR?
Ventilation is more effective with a cuffed endotracheal tube than via mouth-to-snout ventilation.
Marked variability in the size and shape of the face and the presence of fur make mask ventilation challenging in dogs and cats. Early endotracheal intubation is recommended in canine and feline CPR
182
What should happen to chest compressions during intubation of a patient in cardiac arrest?
Chest compressions should not be stopped to facilitate intubation, so staff should be trained to intubate in lateral recumbency. Practice this technique frequently when intubating patients for elective anesthetic procedures.
183
What type of endotracheal tube should be used in CPR?
Only cuffed endotracheal tubes should be used, unless an appropriately sized endotracheal tube with a cuff is not available (i.e., very small tubes). Test the cuff by inflating it, then deflate and lubricate the end of the tube with water soluble lubricant. Consider use of a stylet to facilitate intubation, especially for small endotracheal tubes
184
If supplies to intubate the patient are not immediately available then what should you do?
If supplies to intubate the patient are not immediately available, mouth-to-snout ventilation should be done. As soon as it is possible to intubate the patient, intubated ventilation should be started. Here are the steps for mouth-to-snout ventilation.
185
How do you carry out mouth to snout ventilation?
Hold the patient’s mouth closed firmly with one hand.
Extend the neck to align the snout with the spine, opening the airway as completely as possible.Make a seal over the patient’s nares with your mouth and blow firmly into the nares to inflate the chest.
Watch the chest during the procedure, and continue the breath until a normal chest excursion is accomplished. Aim for an inspiratory time of approximately 1 second.
186
What are the goals of respiratory support during CPR?
The goals of respiratory support during CPR are to provide both ventilation and oxygenation.
Ventilation: Excretion of carbon dioxide produced in the tissues as a by-product of metabolism
Oxygenation: Transportation of oxygen into the arterial blood for delivery to tissues for metabolism
187
What happens to patients when they are inadequately ventilated during CPR?
Increased arterial CO2
–
Hypoventilation leads to increased arterial carbon dioxide concentrations, which in turn leads to dilation of peripheral blood vessels and pooling of blood in the periphery.
Decreased perfusion to the brain, heart, and lungs
–
Even with ideal chest compressions, cardiac output generated during CPR is only approximately 30% of normal. Diverting blood to the periphery due to vasodilation results in decreased perfusion to the core organs, such as the brain, heart, and lungs
Increased intracranial pressure
–
The cerebral vasculature is extremely sensitive to carbon dioxide concentrations in the arterial blood. Cerebral vasodilation secondary to hypoventilation can lead to increases in intracranial pressure, further decreasing cerebral perfusion.
188
What are the consequences of hyperventilation during CPR?
Consequences of Hyperventilation
Hyperventilation leads to decreased arterial carbon dioxide concentration, which causes cerebral vasoconstriction, increasing the resistance to blood flow to the brain and compromising cerebral perfusion.
In addition, excessive positive pressure ventilation leads to higher mean intrathoracic pressure, causing compression of the venae cavae and reducing preload to the heart, ultimately resulting in decreased cardiac output.
Finally, low arterial carbon dioxide concentrations decrease the ventilatory drive and reduce the likelihood patients will spontaneously ventilate if return to spontaneous circulation is achieved.
189
How does performing chest compressions compare in an intubated patient and a non intubated patient?
In non-intubated patients ventilated using the mouth-to-snout technique, breathing cannot be performed simultaneously with chest compressions.
Chest compressions, then, must be paused briefly in order to provide mouth-to-snout breaths. This is the primary reason that intubation is recommended as soon as possible. When using a cuffed endotracheal tube, positive pressure breaths can be delivered simultaneously with chest compressions.
190
What steps should be taken to deliver basic life support in non intubated patients?
Follow these steps to deliver basic life support in non-intubated patients using mouth-to-snout breaths:
Deliver 30 chest compressions at a rate of 100 to 120 compressions per minute.
Count each compression out loud so that the team knows when 30 compressions have been delivered.
Pause compressions briefly, and deliver 2 mouth-to-snout breaths. As soon as the two breaths are completed (within 3 to 5 seconds), deliver another round of 30 chest compressions at a rate of 100 to 120 compressions per minute.
In order to reduce fatigue, rotate a new compressor every 2 minutes.
191
How many seconds would 1 breath be given during CPR in an intubated patient?
Although normal respiratory rates in dogs and cats are higher, intubated patients should be ventilated at a rate of 10 breaths per minute. That corresponds to delivering 1 breath every 6 seconds. Breaths should be delivered with a short inspiratory time of approximately 1 second.
This low respiratory rate helps avoid hyperventilation, especially since less CO2 is delivered to the lungs during CPR because of the lower-than-normal cardiac output. The short inspiratory time helps facilitate better venous return to the heart, improving cardiac output. We'll discuss why in the next section of this module.
192
Kasey is in cardiopulmonary arrest and requires ventilation, but Dr. Thomas does not have an assistant. What do you think she should do?
Since Dr. Thomas is alone and does not have any help, she should alternate chest compressions and mouth-to-snout breaths. Remember that chest compressions are the most important part of basic life support, and delaying chest compressions to intubate when there is no one to ventilate Kasey will lead to poor circulation. As soon as help arrives, Kasey should be intubated, but in the interim, Dr. Thomas should do single rescuer CPR, alternating cycles of 30 chest compressions with 2 quick breaths.
193
Why is it important to maintain a low respiratory rate during CPR?
With each positive pressure breath, intrathoracic pressure increases, compressing the venae cavae, reducing both the amount of blood returning to the heart and cardiac output due to the decrease in preload to the heart.
Therefore, it is essential to maintain relatively short inspiratory times of approximately 1 second and low respiratory rates of 10 breaths per minute. This reduces the mean pressure within the thorax and improves cardiac output by increasing preload
194
Why doesn't a low respiratory rate lead to a high arterial CO2 during CPR?
As discussed previously, the recommended respiratory rate during CPR of 10 breaths per minute is significantly lower than the usual resting respiratory rate in most dogs and cats. So, why does this low respiratory rate not lead to hypoventilation and a high arterial CO2?
Remember that even with excellent chest compressions during CPR, only about 30% of a normal cardiac output is generally achieved. As mentioned in Module 1, the CO2 excreted via ventilation is produced in the tissues and delivered back to the lungs via the circulation. The low cardiac output achieved during CPR leads to lower CO2 delivery to the lungs, so ventilating at a "normal" rate would likely lead to arterial hypocapnea. By breathing at a lower-than-normal rate, cardiac output can be improved by reducing mean intrathoracic pressure, lowering the risk of arterial hypocapnea by reducing overall ventilation. This is why the guidelines recommend a low target respiratory rate of 10 breaths per minute.
195
Why does a low respiratory rate during CPR improve cardiac output?
A low respiratory rate causes a decrease in the mean intrathoracic pressure and an increase in filling of the heart. This occurs because the lower mean intrathoracic pressure causes less compression of the vena cavae, allowing more blood to return to the heart and increasing cardiac output.
196
What is the effect of a decrease in return of blood to the heart on cardiac output?
Decreased cardiac output
197
What positive pressure ventilation strategy is most effective in dogs like Wilson, and in cats?
Endotracheal intubation is preferred in dogs and cats because ventilation is more effective with a cuffed endotracheal tube via mouth-to-snout ventilation. In addition, mask ventilation in dogs and cats is challenging due to marked variability in the size and shape of the face as well as the presence of fur.
198
You have decided to intubate with a cuffed endotracheal tube.
Should Wilson’s chest compressions be stopped to facilitate intubation?
no
Pauses in chest compressions during CPR are uniformly associated with worse outcome. Because dogs and cats are relatively easy to intubate in lateral recumbency, intubation should occur simultaneously with chest compressions to maintain blood flow and reduce ischemia in the tissues caused by lack of perfusion when chest compressions are stopped.
199
Preparing for the Endotracheal Intubation
Several techniques can be used during CPR to facilitate endotracheal intubation. What is not recommended to facilitate intubation during CPR?
Extending the neck to straighten the trachea, using a laryngoscope to visualize the arytenoid cartilages, and lubricating the end of the endotracheal tube all facilitate intubation of the patient in lateral recumbency, allowing chest compressions to continue. Placing the dog in sternal recumbency may make intubation easier, but will necessitate stopping chest compressions, compromising delivery of oxygen to the tissues and leading to potentially irreversible ischemic damage, and is not recommended during CPR.
200
You ventilate Wilson at a rate of 10 breaths per minute. This is significantly less than the normal respiratory rate of most dogs.
Why is this beneficial for a dog in Wilson’s condition?
Even with optimal chest compressions, Wilson’s cardiac output is only about 30% of normal, so much less carbon dioxide is being delivered to the lung. Therefore, a normal respiratory rate would lead to hyperventilation and vasoconstriction, reducing blood flow to the brain. For patients receiving positive pressure ventilation, higher respiratory rates also lead to increased mean intrathoracic pressure, which compresses the vena cavae and reduces cardiac output. However, because breathing is driven by high carbon dioxide concentrations, low respiratory rates actually stimulate spontaneous breathing, and also lead to high carbon dioxide concentrations in the blood, which would cause peripheral vasodilation.
201
What is the recommended way to provide ventilation to a dog or cat during CPR?
intubation with an endotracheal tube
202
Should you stop chest compressions so that intubation can be performed?
Chest compressions should not be stopped to facilitate intubation, so staff should be trained to intubate in lateral recumbency. Practice this technique frequently when intubating patients for elective anesthetic procedures.
203
Which of the following are potential consequences of hypoventilation?
The consequences of hypoventilation are increased intracranial pressure, dilation of peripheral blood vessels, pooling of blood in the periphery, or decreased perfusion to the brain, heart, and lungs.
204
describe the relationship between respiratory rate, intrathoracic pressure, and the filling of the heart?
A low respiratory rate causes a decrease in the mean intrathoracic pressure and an increase in filling of the heart. This occurs because the lower mean intrathoracic pressure causes less compression of the vena cavae, allowing more blood to return to the heart and increasing cardiac output.
205
What are the goals of respiratory support during CPR?
Ventilation: Excrete carbon dioxide produced in the tissues as a by-product of metabolism
Oxygenation: Transport oxygen into the arterial blood for delivery to the tissues for metabolism
206
What happens to the cardiac output during IPPV?
During PPV, positive pressure is created in the thorax, which causes:
Less filling of the venae cavae and less blood delivered back to the heart
A decrease in cardiac output
207
Wilson is a 4-year-old male intact Viszla who escaped from his yard and was hit by a car. The owner drove immediately to your hospital, and your initial ABC assessment showed no airway obstruction, no sign of breathing, and no pulse.
You suspect that Wilson is in cardiopulmonary arrest and you have started chest compressions.
Respiratory support should be initiated as soon as possible.
What is not an effect of positive pressure ventilation during CPR?
The goals of respiratory support are to facilitate excretion of carbon dioxide from the body and uptake of oxygen into the arterial blood for delivery to tissues. However, a deleterious effect of positive pressure ventilation is compression of the vena cavae and reduced return of blood to the heart, which decreases cardiac output.
208
Several techniques can be used during CPR to facilitate endotracheal intubation. What is not recommended to facilitate intubation during CPR?
Extending the neck to straighten the trachea, using a laryngoscope to visualize the arytenoid cartilages, and lubricating the end of the endotracheal tube all facilitate intubation of the patient in lateral recumbency, allowing chest compressions to continue. Placing the dog in sternal recumbency may make intubation easier, but will necessitate stopping chest compressions, compromising delivery of oxygen to the tissues and leading to potentially irreversible ischemic damage, and is not recommended during CPR.
209
Inadequate ventilation leads to increases in arterial carbon dioxide, which has several detrimental effects. What is not a consequence of hypoventilation?
There are several detrimental effects of hypoventilation. Peripheral vasodilation leads to pooling of blood in the periphery, resulting in decreased perfusion to heart and brain. Cerebral vasodilation also results from hypoventilation, causing brain swelling, increased intratracheal pressure, and reduced blood flow to the brain. However, high arterial carbon dioxide concentrations will stimulate respiration rather than decrease ventilatory drive.
210
You ventilate Wilson at a rate of 10 breaths per minute. This is significantly less than the normal respiratory rate of most dogs.
Why is this beneficial for a dog in Wilson’s condition?
Even with optimal chest compressions, Wilson’s cardiac output is only about 30% of normal, so much less carbon dioxide is being delivered to the lung. Therefore, a normal respiratory rate would lead to hyperventilation and vasoconstriction, reducing blood flow to the brain. For patients receiving positive pressure ventilation, higher respiratory rates also lead to increased mean intrathoracic pressure, which compresses the vena cavae and reduces cardiac output. However, because breathing is driven by high carbon dioxide concentrations, low respiratory rates actually stimulate spontaneous breathing, and also lead to high carbon dioxide concentrations in the blood, which would cause peripheral vasodilation.
211
What is the ideal amount of people that should be involved in a CPR and what are the roles?
```
5 people
Leader
Compressor
Ventilator
Drug handler
Recorder
```
If additional personnel are available, they can be assigned to other useful roles during CPR. For example, team members can communicate with the clients to confirm code status and keep them apprised of the team’s progress, retrieve additional supplies that may be needed, and rotate in to assist with chest compressions if other team members are fatiguing.
212
What is the role of the team leader during CPR?
The team leader is generally the most experienced person available, and must self-identify immediately when a cardiopulmonary arrest is diagnosed. The team leader is an organizer, not a dictator. The first task is to rapidly assign a compressor and a ventilator to initiate basic life support. If only one additional staff member is available, the team leader must assume one of these roles; however, the team leader should avoid taking on specific CPR tasks if possible so he/she can keep the team organized, solicit input from the team, intermittently summarize the preceding events, and keep in mind the big picture. Once BLS has been initiated, the team leader should assign roles to any additional staff that are available.
Rapidly organizes the team
Maintains perspective on the “big picture”
Guides the CPR
Empowers team members to contribute to the process and to challenge the direction of the intervention when appropriate
Maintains a collaborative atmosphere
Maintains and actively promotes an environment that encourages good teamwork and intellectual participation
213
What is the role of the compressor during CPR?
The compressor should be the first role assigned by the team leader. This team member will immediately start chest compressions at 100-120 / minute to a depth of 1/3-1/2 the width of the chest, and continue compressions, uninterrupted, in cycles of 2 minutes. After 2 minutes, the compressor should rotate out of this role to reduce fatigue and maximize the effectiveness of the chest compressions. In general, to minimize confusion, the compressor and ventilator should switch roles every 2 minutes, allowing the other team members to focus on their assigned tasks exclusively.
214
What is the role of the ventilator during CPR?
If a cuffed endotracheal tube is available, the ventilator should intubate the patient in lateral recumbency while the compressor continues chest compressions. Once the patient is intubated, the ventilator should inflate the cuff, secure the endotracheal tube, and begin ventilating at a rate of 10 / minute (one breath every 6 seconds).
215
What is the role of the drug handler during CPR?
If intravenous access is not available, the drug handler should place an IV catheter and then begin drawing up and labeling the drugs most commonly used during CPR. As drugs are ordered by the team leader, the drug handler administers them. By drawing up and labeling drugs in advance, delays in administration are minimized.
216
What is the role of the recorder during CPR?
The recorder allows the team to more completely adhere to the CPR treatment algorithm by noting the start time of each cycle of CPR, alerting the compressor and ventilator to the approaching end of a cycle so that they can efficiently exchange roles and minimize interruptions in chest compressions, and recording the times and doses of all drugs administered. It can be extremely challenging for team members engaged in other crucial tasks to keep track of time, and a dedicated recorder can help alleviate many potential mistakes or oversights that could compromise patient outcomes
217
what tasks should effective team leaders should strive to achieve?
The team leader must rapidly and clearly assign available staff to specific roles. The order of assignment should be based on the relative priority of the task to be completed, and with consideration of the level of training and experience of each individual.
In order to maximize the ability of each team member to contribute to the intervention, the team leader must ensure that all members of the team share the same mental model. By intermittently summarizing the status of the patient and the therapies employed thus far, the leader can prevent misunderstandings and enhance each team member’s ability to offer insights or ideas that may improve the patient’s outcome. The ideal time to summarize during a CPR attempt is during the 2 minute cycles of chest compressions.
The team leader should act as organizer, not dictator. Actively soliciting input from team members is the best way to take advantage of the insights of all members of the team, some of whom may have observed something missed by the team leader or may have knowledge of other relevant patient information. It is also important for the team leader to acknowledge input offered by a team member, even if the leader chooses not to act on the information immediately. This creates an environment of mutual respect essential to open communication and participation. Drawing on the experience and knowledge of all members of the team allows the leader to make the best-informed decisions and offer the best possible outcome.
When team members have conflicting opinions on the next course of action, it is ultimately the team leader’s responsibility to make a decision and move the team forward. Acknowledging the alternate opinion and assuring all team members that their input was considered and valued will preserve an atmosphere of mutual respect even in the face of opposing views.
218
What are the basic principles of good communication?
Communicate the information in a concise manner. Important information must be communicated efficiently, especially in a busy practice environment. Unnecessary detail or background information can interfere with the transfer of information. Taking a short pause before communicating can allow you to distill the information you need to present into the most concise package containing only the salient information and maximizing the chance your message is heard.
Convey information that is plainly understood. Avoid the use of unnecessary jargon or excessive detail about how you reached your conclusion. Avoid "burying the lead" by providing unnecessary detail, and jump straight to the "headline" by offering up the critical conclusion or piece of information first, then filling in the detail later if necessary.
Offer and request information in an appropriate timeframe. When information that is critical for managing a patient's care needs to be conveyed, it's critical that the information is transmitted in a timely manner. For critically ill patients, not taking action because crucial information was not relayed in time can have devastating effects.
219
What is closed loop communication?
One simple tool that can reduce medical errors due to miscommunication is the check-back, or closed loop communication. The sender directs a message at a specific member of the team, and that team member repeats the message back to the sender in order to confirm the message was received correctly. We'll see some examples of closed-loop communication later in the module.
220
What observational and communication skills should team members adopt during CPR and other emergency interventions?
Situation awareness
While focus on the assigned task is crucial, situation awareness is the concept that all team members should be aware not only of their role in the intervention, but also of the status of the patient and the overall progression of the case. Evaluating the patient directly, listening to input from the team leader and other team members, and being aware of the therapies being administered allows each team member to offer informed opinions and insight when treatment decisions are made. Note that the skill of situation monitoring leads the team leader to a state of situation awareness.
Cross monitoring
The stress and time pressures of a crisis like a cardiopulmonary arrest increase the likelihood of medical errors. Therefore, team members must “watch each other’s backs” and directly but supportively alert colleagues when errors are noted. This can be especially difficult for more junior staff members, but ultimately, patient safety must be the top priority, and all team members must feel empowered to speak up.
Shared mental model
The ultimate goal of teams with good situation monitoring skills is the development of a shared mental model among all team members, where everyone is “on the same page” and has a thorough understanding of the status of the patient, the rationale for the current therapies, and the time course of the intervention. When all team members share the same mental model, they can optimally contribute to decision-making and maximize the likelihood of a successful outcome.
221
What is a debrief after CPR?
At the end of every CPR attempt or crisis situation, a short debriefing session can help maximize each team member's opportunity to learn from the event and improve future performance. During debriefing sessions, the team leader should act as a facilitator, not as a teacher or critic.
During the debriefing, team members should:
Participate proactively
Discuss issues with each other
Thoroughly analyze and understand the situations that confronted them during the code event
The team leader’s goal is to enable the team to find solutions using the leader’s expertise as an instructor to enhance the team’s understanding of missed points.
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How do you perform a debrief after CPR?
At the beginning of the debriefing, the team leader must set the expectation that all team members participate actively. The team leader should not treat the debriefing as a lecture.
Exploring what did not go well is a critical part of debriefing.
To facilitate the discussion, the team leader should ask open-ended questions, such as “what went well with that code?” or “what lessons did you learn from this code?”
Active listening should be included in every debriefing.
When team members ask direct questions, the team leader should turn questions back to the team for discussion, allowing the team to discover their own answers rather than turning those situations into lectures.
During debriefings, discussing uncomfortable issues can sometimes lead to awkward silences. Allowing that silence to linger for a short period of time can help draw team members out and encourage participation.
Debriefings should be allowed to continue until all major issues are discussed by the team and noted by the team leader.
Conclude the debriefing by identifying areas of good performance and areas in need of improvement.
223
How do you keep a discussion moving in a debriefing after a CPR?
An effective CPR effort requires a team of people working effectively together.
The team leader can use open-ended questions to keep the discussion moving if team members are hesitant to contribute.
Asking open-ended questions such as “what went well with that code?” or “what lessons did you learn from this code?” are good ways to open the discussion.
Questions such as “was there anything about how the team handled the situation that made you uncomfortable?” can also help deepen the discussion.
Following up on issues raised by team members and expanding on them by asking questions such as “why, what, and how” can also lead to deeper and more detailed discussions.
When team members ask the team leader direct questions, it is best to turn these questions back to the team for discussion. Using this technique provides team members the opportunity to discover their own answers, rather than turning those situations into lectures.
To keep the discussion moving, use a variety of verbal and non-verbal active listening skills, such as:
Echoing back something that was said.
Reflecting, or repeating something back in different words to show that you understood.
Expanding upon something said by a team member to facilitate further discussion
Areas in which performance was good.
Areas in which performance could be improved.
Suggestions made by the team to improve future performance.
224
During a debriefing what should the facilitator encourage the team to do?
During a debriefing, the team leader should act as a facilitator and encourage the team to:
Discuss what did not go well
Actively listen
Allow silence to linger
Continue until all major issues are discussed by the team and noted by the team leader
Conclude the debriefing with a brief summary of areas that the team has identified as good performance and areas needing improvement
225
To improve efficiency and reduce delays, the drug handler should draw up and label doses of commonly used arrest drugs in advance. true or false?
True
