Cardiac Issues for the Anesthesia Provider

Educational Objectives

The goals of this program are to improve outcomes after perioperative cardiac arrest and to support decision making about pre-treatment with atropine in pediatric patients. After hearing and assimilating this program, the clinician will be better able to:

1.   Identify appropriate candidates for cardiopulmonary resuscitation before defibrillation.

2.   Use vasopressors effectively in the management of cardiac arrest.

3.   Manage perioperative cardiac arrest.

4.   Delegate responsibility when responding to a code.

5.   Determine whether pretreatment with atropine is warranted in pediatric patients.

Faculty Disclosure

In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the plan­ning committee to disclose relevant financial relationships within the past 12 months that might create any personal con­flicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, the faculty and planning committee reported nothing to disclose.

Perioperative Cardiopulmonary Resuscitation: Making the Best of a Bad Situation

Randolph H. Steadman, MD, Professor and Vice Chair, Department of Anesthesiology, David Geffen School of Medicine at the University of California, Los Angeles

Controversial topics in 2005 International Guidelines on Cardiopulmonary Resuscitation (CPR) and Emergency Cardiac Care: delaying defibrillation  —  consider chest compression before defibrillation; study shows that patients who receive CPR first respond better to defibrillation; ventricular fibrillation (VF) and ventricular tachycardia (VT) require large quantities of adenosine triphosphate (ATP); CPR may “wash out” ATP metabolites that accumulate during period of no flow, thus making heart more responsive to defibrillation attempts; may pertain only to patients in field; delaying defibrillation “probably not appropriate” for inpatients (delays >3 min associated with decreased survival); compression to ventilation ratio  —  15 to 2 previously established as single-provider ratio; better out­comes associated with ratio of 30 to 2 for single rescuer (provides least interruption to chest compression); guide­line calls for effective CPR with minimal interruptions; 1 vs 3 shocks for VF  — already recommended by European Resuscitation Council; adopted in 2005 by American Heart Association (AHA); little evidence for better survival with 3 shocks; one shock allows CPR with fewer interruptions; with biphasic defibrillators, initial recommended dose 150 to 200 J; 360 J recommended with monophasic defibrillators

Algorithms

Hypothetical case: patient in intensive care unit (ICU) has cardiac arrest; use defibrillator if readily available (if not available, begin compressions until defibrillation possible); no need for ventilation if defibrillation prompt (better to aim for return of spontaneous circulation); if defibrillation started within several minutes, 50% to 60% chance of returning to spontaneous circulation

If organized rhythm does not return: chest compressions recommended; consider intravenous (IV) medication; animal data suggest better outcomes with vasopressin than with epinephrine; in study of 40 patients treated in field with either drug followed by chest compression, vasopressin associated with better rate of survival to hos­pital admission and to 24 hr; no significant difference between rates of survival to discharge; AHA deems drugs equivalent for treating refractory VF or VT; vasopressin has longer duration of action (10-20 min); single dose recommended; no placebo-controlled trials show use of any vasopressor for cardiac arrest improves survival to discharge; high doses of epinephrine (>1 mg/dose) may be harmful (no longer recommended); if VF persists after vasopressin administration, defibrillate (administer medication; circulate with chest compressions for 60-90 sec; then defibrillate); antiarrhythmic drugs  —  little evidence of efficacy; AHA no longer recommends; magnesium indicated only for torsades de pointes; amiodarone  —  several studies show association with improved survival to hospital admission (but not powered to show survival to discharge); considered alternative to lidocaine for shock-refractory VF or VT; effective for treating atrial and ventricular arrhythmias, low ejection fraction, and Wolf-Parkinson-White syndrome; for pulseless states, recommended dose 300 mg in 20 mL; for other arrhyth­mias, recommended dose 150 mg in 20 mL; side effects include hypotension and bradycardia; administer slowly

Algorithm for VF or VT: administer oxygen; shock patient; administer epinephrine or vasopressin; shock again; consider antiarrhythmic agent; chest compression emphasized (along with defibrillation)

Pulseless electrical activity (PEA): cognitive aid recommended for recall of “5 Hs” and “5 Ts” (reversible causes of adult cardiac arrest); emphasized causes — hypovolemia (most common perioperative cause of PEA); cardiac tamponade (associated with insertion of central line) and tension pneumothorax (may be precipitated by posi­tive-pressure ventilation) suspected with sudden onset of PEA

Central venous pressure (CVP): does not predict fluid responsiveness; high and low CVP associated with volume excess or deficit; helpful in selected cases (eg, superior vena cava syndrome; look for distended neck veins)

PEA algorithm: administer CPR; determine if shockable and if cause reversible; administer epinephrine every 5 min; administer atropine for bradycardia

Bradycardia algorithm: no change in 2005; attend to airway, breathing, and circulation; consider whether defi­brillation appropriate; if symptomatic, consider early transcutaneous (TC) pacing and atropine; if TC pacing effective, consider transvenous administration

Comparison of vasopressin and epinephrine for out-of-hospital CPR: conducted in 33 European communities; pa­tients received either vasopressin or epinephrine; study drug repeated after 3 min; additional epinephrine given as needed; among patients with asystole, 4% in vasopressin group and 1.5% in epinephrine group survived to hospi­tal discharge (P=.04); conclusion  —  vasopressin possibly superior for some conditions; speaker favors it in low flow and hypotensive states; longer half-life beneficial in perioperative period

Tachycardias: look for symptoms of end-organ ischemia (eg, altered mental status, chest pain, hypotension); if tachycardia unstable, determine if wide or narrow; always consider electrical cardioversion first, especially in anesthetized patient

Perioperative cardiac arrest: compared to prehospital arrest, survival more likely (usually witnessed; often antici­pated; patient’s medical history generally known); 47% of patients return to spontaneous circulation; 34% sur­vive to hospital discharge (both nearly twice rates for prehospital cardiac arrest)

Systolic pressure variations during mechanical ventilation: more often seen in hypovolemia (compared to normo- or hypervolemia), and therefore helpful in its detection

Differential diagnosis: anesthesia-related causes include anesthetic overdose, neuraxial block with sympathectomy, local anesthesia toxicity, malignant hyperthermia, and drug error; 0.5 to 2.0 U vasopressin recommended for per­fusing hypotensive rhythms; consider 20% IV fat emulsion (eg, Intralipid; 1.5 mL/kg to load, then 0.25 mL/kg per hour for local anesthesia toxicity)

Hypothermia (induced after resuscitation): associated with more favorable neurologic outcomes and lower 6-mo mortality than normothermia; evidence suggests modest postresuscitation hypothermia (32^oC-34^oC) may be benefi­cial

In-hospital arrest: in retrospective study of first documented rhythm after in-hospital cardiac arrest, »25% of pa­tients had VF or VT (asystole and PEA each about one-third); conclusion  —  VF and VT less common in in-hospital than in out-of-hospital arrests; overall survival <20% in adults (better in children); VF and VT associated with best rate of survival to hospital discharge in all cases; neurologic outcome good in all groups (ie, concerns about neuro­logic outcome do not justify withholding or stopping CPR)

Cardiac arrest in children: in data from Pediatric Perioperative Cardiac Arrest registry, »50% of arrests secondary to anesthesia; 41% cardiovascular (hypovolemia; hyperkalemia [especially with use of stored blood; consider monitoring T waves or serum potassium])

In-hospital VF: uncommon in children; survival to discharge lower among pediatric than adult patients

Rapid response teams: studies show mixed results

Intraosseus access: upper age limit removed in 2005 (formerly recommended only for children <6 yr of age)

Airway management: laryngeal mask airway now considered advanced airway by AHA (acceptable alternative to endotracheal tube in field)

Leadership skills: clinicians should consider roles in event of code; physician in charge should focus on monitoring rhythm; consider having second person assess pulse; femoral area recommended (does not interfere with airway management); code leader can also perform defibrillation, if necessary, but should not administer chest compres­sions; leader should encourage input, advise members of rhythm being treated, and ask for suggestions; should also talk to family and debrief team if rescue efforts terminated

Conclusions: 2005 AHA guidelines focused on effective CPR, chest compressions with minimal interruptions, and search for shockable rhythm; perioperative arrest more likely to be associated with rhythm other than VF or VT

Questions and answers

Device for intraosseous access: Jamshidi needle recommended; shorter and stiffer than spinal needle (will not bend)

Typical debriefing: discussion of  —  delays in accessing equipment; ensuring availability and compatibility of equipment; how team could have performed better; feelings of grief and loss among team members

Indications for opening chest during CPR: penetrating trauma; diagnostic dilemmas; cardiac tamponade; not gener­ally indicated for VF or VT

Use of extracorporeal membrane oxygenation (ECMO): speaker recommends only if equipment and expertise readily available (eg, in cardiac surgery) in select patient population; effort not generally justifiable

When to terminate code: consider patient’s age, etiology of arrest, and patient’s response to resuscitation efforts; anesthetized patients slightly hypothermic (may have good neurologic outcome despite prolonged effort); periop­erative arrest more likely to be reversible than, eg, arrest in elderly person at home; indications to stop  —irrevers­ible etiology; patient does not improve despite team’s best efforts; consider assessing blood gases

Does Atropine Prevent Bradycardia Associated with Intubation?

Randall C. Wetzel, MB, Anne O’M. Wilson Professor of Critical Care Medicine and Chair, Department of An­esthesiology Critical Care Medicine, Childrens Hospital Los Angeles; Professor of Anesthesiology and Pediat­rics, Keck School of Medicine, University of Southern California, Los Angeles

Atropine: used by anesthesiologists as antisialogogue and vagolytic; decreases cyclic adenosine monophosphate, leading to chronotropy (change in heart rate) and dromotropy (faster conduction through heart); cardiac effect lasts £60 min after IV dose (intramuscular administration not recommended for managing acute bradycardia)

Other effects: works on respiratory center in brain; blocks activity of vagus and splanchnic afferent nerves; affects smooth muscle and secretory glands; plant form has anticholinergic effects (used for treatment of asthma, diar­rhea, intestinal cramps, and nocturia)

Side effects: pupillary dilation; dry, flushed skin; hallucinations; agitation; hyperthermia; hypertension; delayed in­testinal motility; tachycardia; seizures; “blind as a bat, dry as a bone, red as a beet, mad as a hatter, and hot as a hare” (classic pentad for manifestations of atropine overdose)

Reflex bradycardia: speaker and colleagues analyzed database of patients <12 yr of age who underwent endotra­cheal intubation; all classified as American Society of Anesthesiologists physical status 1 or 2; all patients under­went elective day surgery; investigators looked for use of succinylcholine and atropine; 10,000 immediately previous patients studied; bradycardia defined as >20% decrease in heart rate immediately following intubation, or heart rate <60 bpm within 10 min of intubation

Findings: 972 patients received pretreatment atropine; average age 4.6 yr (4.7 yr among non-pretreated group); 145 of 1500 infants <1 yr of age (9.6%) pretreated; 827 patients 1 to 12 yr of age pretreated (9.7%); 85 patients re­ceived succinylcholine to facilitate intubation (including 16 infants); 14 of 85 (16.5%) pretreated with atropine (including 2 infants [12.5%]); of 69 older children, 12 pretreated with atropine (17.4%); results  —  among pa­tients <1 yr of age, no incidence of bradycardia, regardless of pretreatment status, use of succinylcholine, or intu­bation; of patients developing bradycardia, incidence in pretreated patients 25 in 1000, compared to 50 in 1000 in non-pretreated patients; implications with regard to reflex bradycardia not clear; among patients >12 yr of age with bradycardia, incidence among atropine-treated group 2 in 816 (25 in 10,000) and 43 in 10,000 among non-treated group; therefore, use of atropine associated with 40% decrease in incidence of bradycardia; clinical sig­nificance unclear; 4 of 1000 pretreated patients developed bradycardia after intubation (incidence of 41 in 10,000), compared to 68 patients not pretreated (for incidence of 75 in 10,000); 4 patients (all older children of normal height and weight) received atropine after intubation to treat bradycardia (1 had been pretreated)

Conclusions: no infants <1 yr of age developed bradycardia; use of succinylcholine not associated with bradycar­dia; infants given succinylcholine did not require atropine; incidence of treated bradycardia 4 in 10,000 (includ­ing 1 patient pretreated with atropine; suggests pretreatment does not necessarily prevent bradycardia); anesthesiologist with average pediatric practice may encounter one patient needing atropine pretreatment every few years; atropine decreased incidence of bradycardia in children 1 to 12 yr of age by »40%; anesthesiologist must determine if worthwhile; 3 smaller studies (185 patients) concluded atropine unnecessary; studies using large databases becoming more common (answer questions more effectively than studies based on smaller popu­lations); will be important for quality improvement

Acknowledgements

Dr. Steadman spoke at Annual Meeting and Clinical Anesthesia Update, held May 14-16, 2010, in Costa Mesa, CA, and sponsored by the California Society of Anesthesiologists. For information on the next meeting (to be held May 13-15, 2011, in San Jose, CA), please visit www.CSAHQ.org. Dr. Wetzel was recorded at 48th Clinical Conference in Pediatric Anesthe­siology, held January 29-31, 2010, in Anaheim, CA, and sponsored by the Pediatric Anesthesiology Foundation, Childrens Hospital Los Angeles. The next meeting will be held February 11-13, 2011 (see www.pac.chla-accm.org/49thProgram.pdf). The Audio-Digest Foundation thanks the speakers and the sponsors for their cooperation in the production of this program.

Suggested Reading

Bernard SA et al: Treatment of comatose survivors of out-of-hospital cardiac arrest with induced hypothermia. N Engl J Med 2002 Feb 21;346(8):557-63; Bhananker SM et al: Anesthesia-related cardiac arrest in children: update from the Pediatric Periop­erative Cardiac Arrest Registry. Anesth Analg 2007 Aug;105(2):344-50; Dorian P et al: Amiodarone as compared with lido­caine for shock-resistant ventricular fibrillation. N Engl J Med 2002 Mar 21;346(12):884-90; Gabrielli A et al: Anesthesia advanced circulatory life support. monograph as of February, 2008: The American Society of Critical Care Anesthesiologists and The American Society of Anesthesiologists Committee on Critical Care Medicine, 1-45; Hazinski MF et al: Controversial topics from the 2005 International Consensus Conference on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Sci­ence With Treatment Recommendations. Circulation 2005;112;III-113-III-136; Kudenchuk PJ et al: Amiodarone for resuscita­tion after out-of-hospital cardiac arrest due to ventricular fibrillation. N Engl J Med 1999 Sep 16:341(12):871-8; Lindner KH et al: Randomised comparison of epinephrine and vasopressin in patients with out-of-hospital ventricular fibrillation. Lancet 1997 Feb 22;349(9051):535-7; Rothrock SG, Pagane J: Pediatric rapid sequence intubation incidence of reflex bradycardia and ef­fects of pretreatment with atropine. Pediatr Emerg Care 2005 Sep;21(9):637-8; Wenzel V et al: A comparison of vasopressin and epinephrine for out-of-hospital cardiopulmonary resuscitation. N Engl J Med 2004 Jan 8;350(2):105-13; Wik L et al: Delaying defibrillation to give basic cardiopulmonary resuscitation to patients with out-of-hospital ventricular fibrillation: a randomized trial. JAMA 2003 Mar 19;289(11):1389-95.