CPR

Question 1

What are the two basic components of BLS in CPR? What about ALS?

Answer 1

BLS: Chest compression, Ventilation
ALS: Drug therapy, electrical defibrillation

Question 2

Despite performing a well-executed chest compression, how many percentage of normal cardiac output can it create?

Answer 2

about 30%

Question 3

What are the two main goals for chest compression?

Answer 3

1) Provide pulmonary blood flow to carry oxygen to the body and eliminate CO2
2) Provide systemic arterial blood flow to restore organ tissue perfusion and metabolism

Question 4

How long should you take to assess a patient’s condition and determine whether CPR should be initiated or not?

Answer 4

No longer than 10-15 seconds

1) Any delay in the initiation of CPR on a pulseless patient decreases the rate of ROSC
2) Performing CPR on a patient that is not in CPA carries minimal risks comparing to delaying CPR

• RECOVER said 5-10 sec

Question 5

When does the majority of the coronary perfusion happen during CPR?

Answer 5

At the decompression phase of chest compression

Question 6

How do you determine the coronary perfusion pressure (CPP)?

Answer 6

CPP = Aortic diastolic pressure - Right atrial diastolic pressure

• CPP is also known as myocardial perfusion pressure

Question 7

How long does it take for CPP to reach its maximum?

Answer 7

About 60 seconds

Question 8

Describe how to perform an effective chest compression.

Answer 8

1) Animal’s position: lateral recumbency
2) Rate: 100-120 compressions/min
3) Depth of compression: 1/3 to 1/2 of the chest width
4) Duration: 2 minutes
5) Operator should lock the elbows during the chest compression and not lean on the chest. The shoulder should be directly above the chest.
6) Allow the chest to recoil before the next compression
7) Allow a few seconds at the end of each cycle of chest compression to assess the ECG

Question 9

Describe the cardiac pump and thoracic pump theories.

Answer 9

Cardiac pump: blood flow is created and directed by the direct compression and increased pressure within the heart ventricles and opening up of the aortic and main pulmonary artery valves.
- medium to large keel-chested dogs, flat-chested dogs (e.g. English bulldog, French bulldog - dorsal recumbency), small dogs and cats

Thoracic pump: blood flows is created by increased the intrathoracic pressure, which force the blood from the thorax to the systemic circulation. The heart is simply a conduit.
Diastole in RH happens during recoil when abdominal veins blood return to RA vs diastole in LH happens during compression when pulmonary vessels compressed and return blood to LA.
- Medium to large round chest dogs

Question 10

What is the recommended ventilation rate and tidal volume in the RECOVER Guidelines?

Answer 10

10 breaths/minutes, 10ml/kg, inspiratory 1 sec

Question 11

Why should the higher ventilation rate or tidal volume be avoided during CPR?

Answer 11

It can cause hyperventilation, which can lead to cerebral vasoconstriction due to low PaCO2. It can also increase intrathoracic pressure and impede venous return and reduce the efficacy of chest compression.

Question 12

In a non-intubated patient, how do you perform chest compression and ventilation?

Answer 12

1) Ratio: compressions-to-ventilation = 30:2
2) 2-minute cycle for each operator
3) When performing the snout-to-mouth ventilation, the neck should be extended to align the mouth to the spine. The inspiratory time is about 1 sec.

• 2024 update discourages use of mouth to snout ventilation and encourages the use of tight fitting mask

Question 13

What is the target ETCO2 in dogs and cats during CPR?

Answer 13

> 18mmHg

*2024 update

Question 14

True or False: ETCO2 can be used to evaluate the chest compression efficacy during CPR.

Answer 14

True

During CPR, when the minute ventilation is constant, ETCO2 is proportional to the pulmonary blood flow

Question 15

How does vasopressin work during CPR?

Answer 15

Activates peripheral V1 receptors located at the vascular smooth muscles

Question 16

What is atropine MOA?

Answer 16

It binds to muscarinic cholinergic receptors as an antagonist

Question 17

What is the drug to consider if the patient with VF that is not responsive to defibrillation?

Answer 17

Lidocaine in dogs
Amiodarone in cats

• 2024 update

Question 18

What is the dose for naloxone during CPR as opioid reversal?

Answer 18

0.04 mg/kg IV/IO

Question 19

What is the dose for flumazenil during CPR as benzodiazepine reversal?

Answer 19

0.01 mg/kg IV/IO

Question 20

During CPR, under what condition will you consider sodium bicarb and what is the dose?

Answer 20

Prolonged CPR (i.e. 10-15 minutes)
1 mEq/kg slow IV

Question 21

During CPR, should you supply the patient with 100% oxygen or not? What is your rationale?

Answer 21

Ideally, the patient should maintained normoxemic (PaO2 80 - 105 mmHg). If we can get an arterial blood gas, supply the oxygen to target at normoxemia. If we can’t get an arterial blood gas, the risk of hypoxemia likely outweighs hyperoxemia and supplying patient with 100% oxygen is reasonable.

Question 22

Describe open-chest CPR

Answer 22

1) Place the patient in right lateral recumbency. Identify 4-5th intercostal space (or where the elbow locates when it’s flexed)
2) Clip the hair and quickly perform a sterile preparation
3) Put on sterile gloves. Use a blade or scissors to make an incision into the thoracic cavity cranially to the rib until reaching the pleura. The incision should be from the dorsal margin of the scapula to 3-5 cm above the sternum.
4) Use a hemostat to bluntly dissect the pleura and create an opening that is big enough for the hand to enter the thoracic cavity and reach the heart.
5) Perform a pericardiectomy with a tissue forcep and Metzembaum scissor
4) Start direct cardiac massage. Make sure to compress from apex to base and do not block the aortic or main pulmonary artery outflow tract

Question 23

What are the indications for open-chest CPR?

Answer 23

1) Pericardial effusion
2) Pleural space disease (e.g. pneumothorax, marked pleural effusion)
3) Diaphragmatic hernia or PPDH
4) Thoracic-wall trauma (e.g. flail chest, open-chest trauma, severe rib fractures)
5) Giant breed dog with round chest
6) Intra-OP for open abdominal or thoracic surgery

Question 24

Compared to external chest compression, how much can the coronary perfusion pressure be improved with internal cardiac massage?

Answer 24

Three times

Question 25

Describe Rumel tourniquet.

Answer 25

1. Prepare 12 Fr or 18 Fr red rubber catheter, umbilical tape, mosquito hemostat, scissors 2. Cut the distal part of red rubber catheter into 3-4 cm segment at the end. 3. Pass the umbilical tape around the descending aorta with both end facing outward 4. Pass the hemostat through the cut red rubber catheter. Grasp both end of the umbilical tape and thread them through the red rubber catheter. 5. Move the red rubber catheter toward the aorta till the aorta is compressed. 6. Use the mosquito hemostat to hold the umbilical tape at its exit at the red rubber catheter in a perpendicular angle to keep the aorta compressed

Question 26

True or False: Animals undergo CPA under the care of anesthesia service are 15 times more likely to achieve ROSC than animals in other services in the hospital.

Answer 26

True * Survival rate: about 50%

Question 27

In veterinary medicine, how many percentage of animals died or are euthanized after ROSC before hospital discharge?

Answer 27

85%

Question 28

What are the three phases of ischemia during VF?

Answer 28

**Electrical phase**: - first **4 minutes ** - **Minimal** ischemic damage and adequate cellular energy store for metabolic process **Circulatory phase:** - subsequent **6 minutes** - **Reversible** ischemic damage **Metabolic phase**: - After **10 minutes** - **Irreversible** ischemic damage

Question 29

During CPR, if the duration of VF is known to be longer than 4 minutes, how do you manage it?

Answer 29

Perform a complete chest compression cycle before defibrillation

Question 30

Describe two different electrical defibrillation modalities.

Answer 30

Monophasic defibrillation - Create a unidirectional current between the paddles and across patient's chest - 4-6 J/kg Biphasic defibrillation - Create a current in one direction between the paddles and across patient's chest and create a second current in the opposite direction - 2-4 J/kg

Question 31

Describe how to perform electrical defibrillation.

Answer 31

1) The patient should be placed in dorsal recumbency if possible on an insulated surface. 2) A copious conducting gel should be applied on the paddles. Place the paddles on both sides of patient's chest at the costochondral junction across the heart. 3) Charge the paddles according to the modality (biphasic: 2-4 J/kg) 4) Prior to deliver the current, make a loud and clear announcement of "CLEAR" and make sure no one has any physical contact to the patient. 5) After the defibrillation, perform another cycle of CPR and then reassess the ECG

Question 32

Metabolic consequences of CPA

Answer 32

* sepsis-like syndrome - CV instability - poor glycaemic control - CIRCI *brain injury * myocardial dysfunction

Question 33

During PCA care, early hemodynamic optimization is an important part. What are the targets in this part of management?

Answer 33

MAP 80-120 mmHg SCvO2 > 70% Lactate < 2.5 mmol/L CVP < 10 mmHg

Question 34

What is the target for respiratory management in PCA care?

Answer 34

Normoxemia (SpO94-98%; PaO2 80-100mmHg) Normocapnia (PaCO2 of 32–43 mm Hg in dogs and 26–36 mm Hg in cats)

Question 35

What is the target core body temperature for mild therapeutic hypothermia?

Answer 35

32 - 34 C

Question 36

True or False: MTH should be initiated in dogs and cats that remain comatose as soon as possible after ROSC and maintained for 24–48 hours if mechanical ventilation and advanced critical care capabilities are available.

Answer 36

True * If advanced critical care capabilities including mechanical ventilation are not available, MTH should not be initiated This is no longer the case in the 2024 update. The guidelines do not recommend the active induction of hypothermia (therapeutic hypothermia) after ROSC in dogs and cats. Unlike in human medicine, where targeted temperature management is often used, there is insufficient evidence to support its routine use in veterinary patients. It is crucial to avoid hyperthermia, as it can worsen neurological outcomes. The guidelines recommend maintaining the animal’s body temperature within the normal physiological range (generally between 37.5°C to 39.2°C or 99.5°F to 102.5°F for dogs and cats). If the body temperature exceeds this range, active cooling measures should be implemented to bring it back to the normal range. For animals that are hypothermic post-ROSC (with a body temperature below the normal range), the guidelines recommend a gradual rewarming process. Rapid rewarming should be avoided to prevent complications such as reperfusion injury or hypotension.

Question 37

What is the recommended rewarming rate during PCA care in RECOVER Guideline?

Answer 37

0.25 - 0.5 C/hr

Question 38

True or False: Clinical neuro exam at the first 24 hours of ROSC does not predict poor prognosis.

Answer 38

True It may take up to 72 hours.

Question 39

What is the only therapeutic intervention that has been shown to attenuate myocardial dysfunction in PCA care?

Answer 39

Mild therapeutic hypothermia

Question 40

Define myocardial stunning.

Answer 40

A transient, reversible myocardial dysfunction without cell necrosis after acute ischemic injury. Worsened by: * myocardial no-reflow (endothelial damage, microthromby and decreased RBC deformability) * use of epinephrine * use of defibrillator

Question 41

Describe interposed abdominal compressions

Answer 41

During the recoil phase a second rescuer applies a positive pressure to the abdomen to increase pressure over the vena cava and facilitate venous return to the heart Target pressure 100mmHg, push dorsally not laterally to avoid spleen and liver injury

Question 42

What is the benefit of interposed abdominal compressions?

Answer 42

improved cardiac perfusion pressure and outcomes in human studies

Question 43

Discuss beta effects of epinephrine during CPR

Answer 43

* pros: - vasodilation of coronary arteries - increased cerebral blood flow *cons: - increased myocardial oxygen consumption - decreased hypoxemic pulmonary vasoconstriction - impaired microcirculation - increased risks of tachyarrhythmia

Question 44

Treatment for TdP

Answer 44

Magnesium IV

Question 45

Is coarse or fine VF better in terms of prognosis?

Answer 45

Coarse (waves >3mm)

Question 46

What is an impedance threshold device?

Answer 46

Device to apply at the end of the ET tube during CPR to increase negative intrathoracic pressure during recoil --> improves venous return

Question 47

There's a linear relationship between supranormal oxygen tension post CPA and in-hospital mortality. An increase in 25mmHg paO2 = an increase of ___ % mortality while an increase in 100mmHg = an increase in ____ % mortality

Answer 47

6% 24%

Question 48

POCUS during CPR

Answer 48

POCUS during CPR is to monitor for any potential recovery signs or specific conditions that might be affecting the heart’s ability to restart 1. **Assessing Cardiac Standstill** : If there is complete standstill with no movement, it suggests a poor prognosis, and providers may consider stopping resuscitation in some cases, especially if combined with other factors. 2. **Detecting Organized Cardiac Activity** : The heart might show organized contractile activity, even if there’s no palpable pulse. This is often called pseudo-PEA (pulseless electrical activity), where the heart is beating weakly but not enough to generate a pulse. 3. **Assessing for Reversible Causes** : POCUS can help detect treatable conditions such as cardiac tamponade, pulmonary embolism, or hypovolemia that may be causing cardiac arrest. 4. **Identifying Return of Spontaneous Circulation (ROSC)**