CPR Flashcards
What does CPR stand for?
Cardiopulmonary resuscitation
What is meant by basic life support?
- Establishing airway and ventilation
- Providing chest compressions
Give some signs of progress with CPR
- Pulse can be palpated during compressions
- Colour of mucus membranes improving
- Eye position changes from central to ventromedial
- Pupil size changes, responsive
- ECG changes
- Palpebral, corneal and gag reflex return
- breathing or chest movements
- Muscle twitches
- lacrimation
- Animal regaining consciousness
When should you progress to advanced life support?
If no signs of improvement are seen after 2 minutes of basic life support
What monitoring methods may be used during CPR?
- Continous ECG monitoring
- End tidal capnography
- ET tube placement needs to be regularly checked
- SPO2%
- Blood gas analysis
- Blood pressure
- CO2 production
What may indicate effective CPR?
- CO2 production, shown on capnograph by traice of high teens, ideally <15-20mmHg
- Indicates that organ perfusion is occurring and blood is reaching the lungs in order for CO2 to be breathed ou
Describe cardiopulmonary arrest
- Characterised by acute failure of respiratory and circulatory systems
- Lack of oxygen delivery to tissues and removal of CO2
- Unconsciousness and systemic cellular death
- Cerebral hypoxia
What may cause cardiopulmonary arrest?
- Anaesthetic complications
- Severe trauma (leading to hypovolaemia)
- Severe electrolyte disturbace
- Cardiac disorders
- Cardiorespiratory disorders
- Debilitating or end-stage disease
- Vagal stimulation
- Myocardial hypoxia
- Drugs/toxins
- pH abnormalities
- Temperature problems
What are the 2 classifications of cardiopulmonary arrest?
- Reversible disease process
- advanced disease status
Give examples of reversible disease processes that may lead to cardiopulmonary arrest
- Anaesthetic overdose
- Bradycardia prior to arrest
- Electrolyte imbalances e.g. hyperkalaemia due to urethral obstruction
Give examples of advanced disease statuses that may lead to cardiopulmonary arrest
- Sepsis
- Cancer
- Severe cardiac disease
- Severe lung disease
- Severe CNS disease
Describe the signs of cardiopulmonary arrest
- Apnoea/agonal gasping
- No palpable pulse
- Loss of consciousness
- No heart sounds
- Central eye position, pupils fixed and dilated, dry cornea, no corneal or palpebral reflex
- Bleeding stops at surgical site
- CRT altered
- Mucus membrane grey/blue/white
- General muscle flaccidity
- ECG arrhythmias
What are the possible actions following identification of CPA?
- Do nothing
- Provide basic life support
- Provide basic and advanced/aggressive life support
- Provide basic life support and if there is no response, provide advanced/aggressive life support
What are potential methods for accessing the airway in CPA?
- Orotracheal intubation
- Emergency tracheostomy
How may breaths be delivered to a patient in CPA?
- Mouth to nose ventilation
- Compression of the chest whilst giving oxygen by mask
- Stimulation of GV26 needle (Jen Chung) acupoint may stimulate breathing
- AMBU bag attached to ET tube, or tube in tracheostomy
How can ventilation be provided to horses?
- AMBU bag/bag on breathing circuit attached to ET tube
- Nasal tubes
What are the recommendations for PPV during CPR?
- ~10 breaths/minute
- Do not exceed 20cm H2O
- Care not to overinflate
- Ensure chest wall is moving adequately
- Check femoral pulse, colour and heart sounds within 30 seconds of initiating PPV
What are some potential causes of inadequate chest wall excursion during CPR?
- Tube malposition
- Obstruction
- Pneumothorax
- Diaphragmatic hernia
- Pleural disease
What is the risk with too much ventilation?
- May lead to hypocapnia
- No stimulation for animal to breath by itself
Why is cardiac massage used in CPR?
To artificially generate stroke volume and maintain tissue perfusion, as normal heart activity is reliant on early restoration of myocardial oxygenation and blood flow
Describe the cardiac pump
- Compression of the thorax
- Forces blood through the heart and large vessels
- Each compression forces blood out of the heart, and each release of pressure draws blood back into the heart
Describe the method of performing the cardiac pump
- Start as soon as CPA identified
- Place patient in lateral recumbency on hard surface
- Wedge under thorax to maintain stability if needed
- Compress thorax over ventral 1/3rd of thorax between 3rd and 6th ribs (directly over, or encircling the heart)
- Aim for 100-120 compressions/minute
What modification of the cardiac pump can be used in cats and neonates?
Thorax compressed between thumb and forefinger
Describe the modification of the cardiac pump in barrel or broad chested dogs
Sternal compressions carried out in dorsal recumbency
When is the thoracic pump used in CPR?
- Cardiac pump ineffective in deep chested animals >20kg, obese animals, animasl with microcardia, pericardial effusion or low thoracic compliance (e.g. pneumothorax)
- Instead use thoracic pump
Describe the method of the thoracic pump
- Use both ventricular chambers of herat and the intrathoracic vascular system to generate stroke volume
- Place in lateral recumbency on hard surface, tilt head down slightly
- Compress thorax over widest part of ribcage
- Use whole thorax to generate stroke volume
- 60-12 compressions/min
In what conditions will the thoracic pump be ineffective?
- Animals with severe hypovolaemia
- Incompetent tricuspid valves
What should the ratio of compressions to breaths be if performing CPR alone?
30 compressions to 2 breaths
What other actions may aid the efficiency of external cardiac compressions?
- Alternating with abdominal compressions to push blood towards heart during diastole and prevent pooling in abdomen
- Apply bindings to abdomen and hindlimbs to prevent pooling
What are the potential ECG rhythms that may be seen?
- Asystole
- Ventricular fibrillation
- Sinus bradycardia
- Electromechanical dissociation (EMD) aka Pulseless Electrical Activity (PEA)
What is EMD/PEA?
Normal ECG but no pulse
List the drugs that may be used in CPR
- Adrenaline/epinephrine
- Vasopressin
- Atropine
- Naloxalone
- Flumazenil
- Lidocaine
What is the mechanism of action of adrenaline/epinephrine?
- Adrenergic agonist
- Stimulates alpha and beta receptors
Explain why adrenaline is used in CRP
- Increases myocardial contractility
- Increases heart rate
- Increases myocardial automaticity
- Mainly used for alpha2 effects
- Shunting of blood to brain, heart and lungs
- Increases blood pressure by increasing systemic vascular resistance
- Peripheral arteriolar vasoconstriction increasing coronary and cerebral perfusion pressure
In what conditions is adrenaline commonly used during CPR?
- Asystole
- Atropine resistant bradyarrhythmias
- poor diastolic filling
Describe the beta2 agonist effects of adrenaline
- Smooth muscle relaxation
- Peripheral vasodilation
- Systemic hypotension
- Bronchial dilation
Describe the alpha1 agonist effects of adrenaline
- May be detrimental to myocardium by increasing myocardial oxygen demands
- Cause intramyocardial coronary arteriolar vasoconstriction
- Enhance the reduction in myocardial perfusion
Describe the mechanism of action of vasopression
Stimulates specific V1A receptors in the smooth muscle of the vasculature, leading to non-adrenergic vasoconstriction
Explain why vasopressin may be used during CPR
- Causes peripheral, coronary and renal vasoconstriction
- May improve cerebral perfusion by causing dilatation of cerebral vasculature
- Less constriction in coronary and renal blood vessels vs peripheral tissue, therefore preferential shunting of blood to CNS and heart
In what conditions is atropine used during CPR?
- Vagally mediated bradycardia
- Vagal induced asystole
What are the effects of atropine?
- Increases heart rate
- Controls hypotension
- increases systemic vascular resistance
What is the mechanism of action of atropine?
Is an anticholinergic parasympatholytic that is effective at muscarinic receptors
What are the dosage recommendations for adrenaline?
- Start low, for 2 cycles, 10 mins apart
- Then a dose of high
- Then 2 doses of low
What is naloxalone used for?
Opioid reversal
What is flumazenilin used for?
Benzodiazepine reversal
What is lidocaine used for?
Treatment of ventricular tachycardia
What are the routes of administration for drugs used in CPR?
- Cranial vena cava
- Intraosseous
- Intratracheal
- Pulmonary vein
- Intralingual
- Cephalic vein
Outline cranial vena caval administration of drugs during CPR
- Route of choice for drugs and fluids
- Difficult in CPR due to movement
- Jugular venous cut down, other veins not as effective
Outline intraosseous administration of drugs during CPR
- As rapid as peripheral veins
- Useful in small animals, collapsed animals and birds
- Sites used: greater tubercle of humerus, tibial crest, trochanteric fossa of the femur
Outline intratracheal administration of drugs during CPR
- Dilute the drug and use urinary catheter inserted beyond the carina
- Give several large chest inflations to distribute the drugs
- Higher doses needed
Outline pulmonary vein administration of drugs during CPR
- Rare
- Small needles (23-25G) required
- Only where have access during open chest resuscitations
Outline the intracardiac administration of drugs during CPR
- Not recommended
- Could be used during open chest resuscitations
- 1/2 dose used for IV admin
- If not open chest, then difficult to get correct placement and high risk of severing coronary artery
Outline cephalic vein administration of drugs during CPR
- No blood flow, will not get to heart to be distributed quickly
- Need to add 20ml fluid behind the drug in order to get it into the jugular and the heart
Outline the use of intravenous fluids during CPR
- No need in euvolaemic or hypervolaemic patients, would add pressure to heart
- Only used with documented or suspected pre-existing hypovolaemia
- Not a priority
When is electrical defibrillation used?
To convert ventricular fibrillation arrest rhythm into normal rhythm
What method, other than electrical defibrillation, can be used to correct ventricular fibrillation?
Precordial thump (large hit to chest with fist)
What is ROSC?
Return Of Spontaneous Cirulation
What are the risks for an animal following ROSC?
- Acute anuric renal failure
- DIC
- Shock gut (gut reperfusion syndrome)
- SIRS
- Brain injury (blindness, coma, seizure)
- Hypothermia
How is neurological recovery controlled post-arrest?
- Cerebral perfusion protected
- Ensure mean arterial pressure is optimal
- Achieved with fluid therapy, inotropes and vasopressors
- Use post-ROSC algorithm
Describe the follow up following CPR
- Most animals require intensive care
- Head up to alleviate intracranial pressure increase
- Oxygen rich environment
- Seizures common
- Maintain temperature 33-34degreesC
- Maintain renal function
- Catheterise bladder and monitor urine output
- Consider analgesia and sedation
