Download cardiopulmonary resuscitation - Cornell University Veterinary

CARDIOPULMONARY RESUSCITATION
Daniel J, Fletcher, PhD, DVM, DACVECC
Cornell University College of Veterinary Medicine, Ithaca, NY
Immediate evaluation and intervention are crucial when treating the unresponsive patient who presents to the
hospital or is found while hospitalized. Rapid identification and treatment of life threatening disorders can mean the
difference between life and death. Initial assessment should be completed rapidly using the standard Airway, Breathing,
Circulation (ABC) approach. The airway should be visually inspected to ensure that there are no obstructions, masses, or
fluid causing obstruction. Internal and external palpation of the mouth, pharynx, larynx should follow, and the provider
should manually clear any fluid or debris obstructing your view. Breathing is assessed by visually inspecting for chest
excursions, feeling in front of the nares/mouth for air movement, and/or ausculting the lungs. Circulation is assessed
quickly via palpation of femoral and/or distal pulses and/or cardiac auscultation.
Resuscitation Team
A CPR requires a team of care providers operating efficiently and with excellent communication. A minimum
of 2 individuals is required (leader acts as breather/compressor). The core team consists of the following members: (1)
team leader, (2) compressor, (3) breather. If additional personnel are available, the following supplementary roles may
be assigned: (4) drug pusher, (5) recorder. The team leader ist he individual directing the arrest. His or her major
responsibilities are to keep the broad view, assign other team members tasks, and intermittently summarize the case and
solicit feedback. The compressor is responsible for chest compressions and should rotate every 2 minutes with the
breather. The breather is responsible for ventilations and as noted, should rotate every 2 minutes with the compressor.
The drug pusher draws up and administers drugs as directed by the leader, and should anticipates needs and draw up
drugs that may be needed in advance. The recorder maintains a record of everything that is done with a time stamp,
monitors cycles of CPR (every 2 minutes) and announces end of each cycle, and keeps track of frequency of drug
administration, suggesting when administration should occur.
Organized, explicit, and effective communication is crucial for a successful resuscitation effort. Roles of all
team members must be clearly defined. A leader must be identified immediately, and subsequently quickly assigns roles
to the other team members. Clarity of communication is another key concept. All messages should be specifically
directed at an individual, and requests should be clearly and succinctly stated. Communication should be “closed-loop”,
with the receiver acknowledging each message and repeating it back. Orders should not given “to the room”, but
directed at an individual, with that individual responding that he/she understands. The team leader should make
knowledge sharing a priority by summarizing the status and progression of the case and encouraging team members to
offer ideas/solution/observations. Finally, an atmosphere of mutual respect in which everyone on the team gets a say
and all points of view are acknowledged and valued maximizes the potential for a successful resuscitation effort.
Basic Life Support (BLS)
These procedures should be implemented IMMEDIATELY when a patient has arrested. Priorities for
successful CPR follow, in order, the circulation, airway, breathing (CAB) concept. The first priority in treatment of a
pulseless patient is support of the circulation. This is accomplished with high quality chest compressions at 100-120
compressions/minute. Compression cycles should continue without interruption for 2 minutes. At the end of each cycle,
the compressor and breather should switch roles to reduce fatigue and maintain quality compressions. Optimal hand
placement depends on size of animal For animals less than 10kg, the cardiac pump theory is likely the most effective,
and the hands should be placed directly over the heart (4-6 intercostal space over the costochondral junction) with the
goal of directly compressing the heart. For animals weighing more than 10kg, the thoracic pump theory likely is
predominant, and hands should be placed over the widest portion of the chest with the goal of achieving approximately
30% thoracic compression to increase overall intrathoracic pressure. A 1:1 duty cycle yielding equal times of
compression and elastic recoil allows for filling of the heart between compressions. Interruptions to compression should
be minimized at all costs! Longer delays to start of compressions and longer interruptions in compressions once started
have been associated with a reduced return of spontaneous circulation (ROSC) and reduced survival.
Once compressions have been started, an airway should be secured as soon as possible. Methods for airway
management include orotracheal intubation, tracheostomy, and mouth to snout ventilation. When using orotracheal
intubation, ensure that the tube is correctly placed by briefly stopping compressions and looking for a chest rise. It is
crucial that the cuff be inflated and that the tube is secured to prevent dislodgement during compressions. Tracheostomy
should be done only if an obstruction prevents orotracheal intubation.A slash tracheostomy should be performed quickly
to minimize interruptions to compressions. Mouth to snout ventilation should be used only if intubation equipment is
not available. Hold mouth closed tightly and use a 30:2 cycle (30 chest compressions followed by 2 breaths).
Breathing should be at 6-10 bpm. Hyperventilation causes cerebral and coronary vasoconstriction and worsens
ischemia. The use of supplemental oxygen is controversial due to the potential for oxygen toxicity and atelectasis.
Advanced Life Support
Patients should be monitored closely during CPR. Palpate the femoral pulse continually if possible. If there are
too few team members, palpate the pulse between CPR cycles. Regardless of the ECG, the absence of a pulse means
your patient is still in cardiac arrest. During compressions venous pulses are often palpable and do not reflect
circulation, so interpret pulses only during brief interruptions in chest compressions
Place an ECG as soon as possible after compressions have started. Compressions cause artifact that render the
ECG unusable, so check quickly between cycles of compressions. The team leader should announce the rhythm
diagnosis or solicit input from the team. Therapy depends upon ECG, so an accurate diagnosis is crucial. Common
arrest rhythms include asystole, pulseless electrical activity (PEA), ventricular fibrillation (vfib), and bradyarrhythmias.
If available, end tidal CO2 (ETCO2) monitoring is useful during resuscitation. ETCO2 will be low when
circulation is poor due to decreased delivery of CO2 to the lungs. With return of spontaneous circulation (ROSC),
ETCO2 increases dramatically, and can therefore be useful as early indicator of ROSC
Pharmacotherapy is an important aspect of advanced life support. Vasopressors are used for patients with
asystole, PEA, and persistent vfib. Epinephrine is a catecholamine, and has potent α1, β1, and β2 effects. There is recent
evidence that the α1 effects may be most helpful in CPR. The resulting peripheral vasoconstriction allows the small
stroke volume generated by chest compressions (typically 20-30% of that in a patient with spontaneous circulation) to
maximize oxygen delivery to the core (brain, heart, and lungs). Epinephrine should be redosed every 3-5 minutes. An
alternative vasopressor is vasopressin, which can be used in place of the 1st or 2nd dose of epinephrine. This drug should
only be administered once. It causes peripheral vasoconstriction via V1 receptors. Atropine (an anticholinergic) is
indicated for bradycardias (sinus bradycardias, AV block, sick sinus syndrome) and may be optionally used for asystole
/ PEA. It can be given every 3-5 minutes and can be repeated up to 3 times. Intravenous fluids are indicated in patients
with hypovolemia, but can potentially worsen perfusion in euvolemic patients by increasing venous pressure.
Electrical defibrillation is indicated only in patients with documented ventricular fibrillation. The goal is to use
a high current to depolarize myocardial cells simultaneously and put them into a refractory phase (i.e., to stop the
ventricles from beating). This then may allow pacemakers to restart coordinated contractions. Because it stops the heart,
it is contraindicated for asystole/PEA! Dose ranges vary depending on defibrillator technology (e.g., monophasic vs.
biphasic). Sample dosing charts are included below. If you find the patient in vfib, administer 1 cycle of CPR,
defibrillate and immediately begin another cycle of CPR. Do not check the ECG until after the cycle is complete. If you
see the patient convert to vfib while monitoring the ECG, administer CPR while charging defibrillator and immediatelty
defibrillate, then administer 1 full cycle of CPR before checking the ECG. Remember to shout “CLEAR” and verify
that all personnel are clear before defibrillating.
References
1. Boller, M., Kellett-Gregory, L., Shofer, F. S., & Rishniw, M. (2010). The clinical practice of CPR in small animals:
an internet-based survey. Journal of veterinary emergency and critical care, 20(6), 558-70.
2. Cole, S. G., Otto, C. M., & Hughes, D. (2002). Cardiopulmonary cerebral resuscitation in small animals-A clinical
practice review. Part I. Journal of Veterinary Emergency and Critical Care, 12(4), 261-267.
3. Cole, S. G., Otto, C. M., & Hughes, D. (2003). Cardiopulmonary cerebral resuscitation in small animals-A clinical
practice review. Part II. Journal of Veterinary Emergency and Critical Care, 13(1), 13-23.
4. Neumar, R. W., Otto, C. W., Link, M. S., Kronick, S. L., Shuster, M., Callaway, C. W., et al. (2010). Part 8: Adult
Advanced Cardiovascular Life Support: 2010 American Heart Association Guidelines for Cardiopulmonary
Resuscitation and Emergency Cardiovascular Care. Circulation, 122(18_suppl_3), S729-S767.
5. Travers, a H., Rea, T. D., Bobrow, B. J., Edelson, D. P., Berg, R. a, Sayre, M. R., et al. (2010). Part 4: CPR
Overview: 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency
Cardiovascular Care. Circulation, 122(18_suppl_3), S676-S684.
Biphasic Defibrillator Dosing Chart
Monophasic Defibrillator Dosing Chart