Life-saving measures: A CPR overview in pets
The first evidence-based CPR guidelines for small animals have recently been developed, and in his presentation, “CPR: basic and advanced life support” during the 2013 Veterinary Emergency and Critical Care Society meeting, Daniel Fletcher, PhD, DVM, DACVECC discussed some of the highlights.
Compressions are key. We now know that the ABCs of CPR should really be the CABs since circulation via chest compressions is key to success. Chest compressions should be started within 15 seconds of recognizing that the patient has arrested. Be aware that while you will achieve effective compressions with most patients in lateral recumbency, barrel-chested breeds may be better off on their backs. The rate of compressions should be 100 to 120/min (1 to 2/sec) for dogs and cats. If the airway is clear, mouth to snout respirations (two breaths every 30 compressions) should be started until endotracheal intubation can be performed. Once the patient is intubated, the breathing rate should be 10 breaths/min, or one breath every six seconds.
Monitoring. As for monitoring equipment during CPR, Dr. Fletcher recommends an ECG and end-tidal CO2 (ETCO2) monitor at a minimum. These will be the most helpful in determining how effective you are with compressions and medications. Compressions can be stopped briefly every two minutes to evaluate the ECG for rhythms that may indicate the need for medications or defibrillation. The ETCO2 should be monitored as it is a marker of pulmonary blood flow. An ETCO2 < 15 would indicate the need for more effective compressions. A sudden increase in the ETCO2 would also indicate a return to spontaneous circulation (success!).
Drug therapy. Emergency drugs will also be required in these patients. Epinephrine should be given at a dose of 0.01 mg/kg intravenously every other cycle (about every four minutes). If there is no response after 10 minutes, a high dose (0.1 mg/kg) can be given. If drugs are going to be given via the endotracheal tube, Dr. Fletcher recommends administration with a red rubber catheter to ensure delivery into the lungs. Vasopressin may also be used interchangeably with epinephrine and may be a better choice in patients known to be acidotic. The dose is 0.8 U/kg given intravenously.
Despite its widespread use in CPR, there is little evidence to show that atropine has a beneficial effect. It is relatively safe, however, and may be useful in patients with vagally mediated cardiac arrest. The dose is 0.04 mg/kg given intravenously.
Defibrillation. Consider electrical defibrillation for patients with ventricular fibrillation (not for asystole, despite what they do on Grey’s Anatomy). Continue chest compressions while the machine is charging, and be sure to roll the patient onto its back (dorsal recumbency) to place the paddles on either side of the chest. Apply the shock and continue chest compressions for another cycle. If there is no response, repeat defibrillation with a 50% increase in the dose.
For more information on the CPR guidelines, visit acvecc-recover.org.