Once BLS is underway, begin Advanced Life Support (ALS) if resources allow.

Most dogs will have PEA or asystole as the initial arrest rhythm. Administer ALS drug therapy if ECG capability is not available to dictate whether to use drugs or defibrillation.

Bradycardia due to a pronounced vagal response is common in dogs, and the immediate use of vagolytic therapy (atropine) may prevent impending CPA.5,6

INITIATE MONITORING

Capnometry

End tidal CO2 (ETCO2) is important to monitor during CPR. It indicates efficacy of compressions (higher ETCO2 values associated with increased perfusion, > 12 mmHg can indicate proper endotracheal tube placement, and 18 mmHg is the minimum end-target during CPR).7

An acute rise in ETCO2 can signal ROSC. An ETCO2 cutoff of 18 mmHg is optimal to predict future ROSC.8

Electrocardiogram

Evaluate after each 2-minute cycle of BLS to identify if ROSC has occurred.

Can identify if a shockable rhythm for defibrillation has developed or see if a non-shockable rhythm has developed to prevent unnecessary defibrillation.

OBTAIN VASCULAR ACCESS

Intravenous (IV) or intraosseous (IO) catheters may be used during CPR, but IV drug administration is preferred. (See K9 Normal Clinical Parameters CPG for venous access anatomy).

ADMINISTER DRUG REVERSALS

- Naloxone (for opioid reversal) – 0.01 – 0.04 mg/kg IV/IO, intramuscular (IM), subcutaneous (SC) or intranasal (IN).
  - Repeat every 1-2 minutes if required, to effect.
  - If IM, IN or SC, effects may be delayed up to 5 minutes.
- Flumazenil (for benzodiazepine reversal) – 0.01 – 0.02 mg/kg IV/IO, repeat every hour if needed.
- Atipamezole (for alpha-2 adrenoreceptor agonist reversal) – inject the same volume IV or IO as was used for dexmedetomidine or medetomidine.

EVALUTE ELECTROCARDIOGRAM (ECG)

Perform quickly, with no more than 10 seconds of interruption in chest compressions. Continue BLS and re-evaluate ECG after each 2-minute cycle.

Intervene according to rhythm with either ALS drugs (every other cycle) or defibrillation and repeat until ROSC is achieved or CPR efforts are halted.

- ROSC – do not resume compressions, enter post-resuscitation care.
- Asystole or PEA – administer vasopressor NOW and every 3 to 5 minutes (roughly every other cycle of CPR). If IV/IO access is not available, can give intratracheal at 5-10 times the dose, diluted with sterile saline and administered through a catheter longer than the endotracheal tube.
  - Vasopressor
    - Low dose epinephrine – 0.01 mg/kg IV or IO.
    - High dose epinephrine is not recommended.9
    - Vasopressin – 0.8 U/kg in place of epinephrine, but improved survival has not been noted.
  - Atropine – consider a single dose at 0.04 mg/kg IV, particularly if arrest was vagally-mediated.
  - Lidocaine – 2 mg/kg IV can be administered if refractory pulseless ventricular tachycardia or ventricular fibrillation is present after the initial shock has been unsuccessful. If lidocaine is unavailable, amiodarone can be administered (5 mg/kg IV).
  - Apart from the medications listed above, no other routine medications are recommended during CPR.
    - Corticosteroids are not recommended.
    - Fluids are not recommended unless hypovolemia is causing the CPA.
    - Alkalinization therapy (sodium bicarbonate 1 mEq/kg IV) may be considered in prolonged CPA (> 10 – 15 minutes). This may cause increased ETCO2 that is not related to ROSC.
    - Magnesium infusion can be considered for treatment of torsades de pointes (Table 1).
    - Amiodarone infusion can be considered in ventricular tachycardia (VT) or ventricular fibrillation (VF) that is refractory to defibrillation and is preferred over lidocaine for this indication (Table 1).
- Ventricular fibrillation or pulseless ventricular tachycardia – administer external defibrillation. Continue BLS while preparing for defibrillation. If CPA occurred > 4 minutes prior to rhythm diagnosis, finish the 2-minute cycle of BLS. If CPA occurred < 4 minutes, administer the shock as soon as the defibrillator is charged.
  - A biphasic defibrillator should be used to deliver shock at a dose of 2 J/kg (first attempt) and 4 J/kg (second and subsequent attempts).9
    - Avoid using alcohol during defibrillation to reduce risk of fire.
    - Place patient in dorsal recumbency with forelimbs secured overhead and out of contact.
    - Apply conductance paste or conductive electrode gel liberally to both paddles.
    - Place paddles on opposite sides of the thorax at costochondral junction and directly over the heart (4th – 6th rib space) and squeeze together to ensure firm pressure.
    - Charge paddles, then CLEAR all personnel; visually confirm no one is contacting the patient or the table, then discharge defibrillator.
    - Resume full 2-minute cycle of BLS before re-evaluating ECG.