Critical Care

From High Risk Emergency Medicine, sponsored by the Departments of Emergency Medicine
at San Francisco General Hospital and the University of California, San Francisco, School of Medicine

Amal Mattu, MD, Professor of Emergency Medicine and Program Director, Emergency Medicine Residency,
University of Maryland School of Medicine, Baltimore

Educational Objectives

The goal of this program is to improve the management of the critical patient in the emergency department (ED). Af­ter hearing and assimilating this program, the clinician will be better able to:

1.   Recognize that the classic presentation of pain in abdominal aortic aneurysm and aortic dissection is often not present.

2.   Communicate with the ED staff about the importance of avoiding hyperventilation in a patient who is severely hypovolemic or in cardiac arrest.

3.   Utilize all forms of electrical therapy on a pregnant patient in cardiac arrest.

4.   Implement therapeutic hypothermia in a postmyocardial infarction patient in cardiac arrest before, during, and after cardiac catheterization.

5.   Recognize the importance of performing bedside ultrasonography or echocardiography in a crashing or arrest­ing patient.

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, Dr. Mattu and the planning committee reported nothing to disclose.

The Crashing Patient: Beyond ABC and ACLS

Case: man, 55 yr of age, transported by ambulance for feeling ill; denies pain; awake, diaphoretic, and appears ill; vi­tal signs  —  afebrile; tachycardic (heart rate [HR] of 100 beats/min [bpm]), respiratory rate 28 breaths/min, and sys­tolic blood pressure (BP) 85 mm Hg; started on intravenous (IV) fluids and O₂; electrocardiography (ECG) shows nonspecific changes

Airway breathing circulation (ABCs): from first Advanced Trauma Life Support (ATLS) course designed by ortho­pedic surgeon; not designed for individuals trained in emergency medicine or trauma

Aorta: 2004 study  —  looked at Austrian registry of patients who died of ruptured abdominal aortic aneurysm (AAA) or thoracic aortic dissection and noted that atypical presentations common; classic presentation of AAA includes abdominal or back pain, pulsatile mass, and hypotension; classic presentation of aortic dissection is sharp, ripping, tearing pain from chest to back and pulse deficit; word “classic” in medicine means 15%; in ruptured AAA patients who eventually died, only 50% had any abdominal or back pain; in aortic dissection patients who eventually died, only »50% had chest or upper back pain; pulseless electrical activity (PEA) most common presenting rhythm when patients went into cardiac arrest; resuscitation literature shows that PEA arrest good time to administer empiric thrombolytics because of likelihood of pulmonary embolism (PE) or massive myocardial infarction (MI); however, ruptured AAAs and dissection also tend to present with PEA arrest; bedside ultrasonography (US)  —  extremely im­portant; easy to detect AAA, unless patient morbidly obese; death in most patients with aortic dissection due to pericardial tamponade (pericardial effusion seen on US); in ill-appearing patient, obtain US of heart and aorta, re­gardless of whether pain present

Case: nursing home patient, 58 yr of age, presents with decreased level of consciousness; febrile, dehydrated, hypo­tensive, tachypneic, and tachycardic; diagnosis of sepsis; blood gases showed pH of 7.15, Pco₂ of 18 mm Hg, and serum bicarbonate of 10 mEq/L; given fluids (normal saline) and antibiotics; intubated, with tube placement con­firmed; placed on ventilator at 15 breaths/min, tidal volume of 400 to 450 mL, and fraction of inspired O₂ of 100%; shortly after intubation, has bradyasystolic arrest

Metabolic acidosis: primary metabolic acidosis compensated by hyperventilation (respiratory alkalosis), which improves pH; by paralyzing case patient, respiratory compensation removed; by placing patient on ventilator at rate of 15 breaths/ min, pH reduced even more, inducing bradyasystolic arrest; if delays in intubation present, must administer serum bicarbonate to maintain pH; once intubated, utilize ventilator settings that reproduce minute ventilation before patient paralyzed (in case patient, 30 breaths/min); hyperventilate patient during and af­ter intubation while on ventilator; if patient severely hypovolemic or in cardiac arrest, do not hyperventilate; data from animal and human literature show higher mortality if patient hyperventilated while in cardiac arrest; Ameri­can Heart Association (AHA), Advanced Cardiac Life Support and Basic Life Support  guidelines currently recom­mend that when patient in cardiac arrest, bagging should be performed 12 times/min; however, study showed that average bagging rate in emergency departments (EDs) 56 times/min; bagging increases intrathoracic pressure that decreases venous return and left ventricular (LV) filling, decreasing cardiac output and coronary perfusion; data show that hyperventilation associated with increased mortality; cerebral blood flow also decreased, thus hyperven­tilation associated with decreased neurologic survival; drop in BP seen with intubation (concerning in patient al­ready hypovolemic); for nonprofessional rescuers, mouth-to-mouth resuscitation no longer recommended to avoid decrease in venous return which decreases cardiac output and cerebral blood flow

Baby on board: in crashing, arresting woman, always consider ruptured ectopic pregnancy; should not rely on pres­ence of tachycardia; common to not see tachycardia in patients bleeding into pelvis (paradoxic vagal reaction); also true for bleeding into pelvis from trauma and ruptured AAA

Case: woman, 24 yr of age, in third trimester of pregnancy presents with ventricular dysrhythmia; hemodynamically stable; amiodarone  —  avoid in pregnancy; class D, while other antiarrhythmics class B or C; even short courses can lead to fetal problems, hypothyroidism, intrauterine growth retardation, fetal bradycardia, and prematurity; all forms of electrical therapy (eg, defibrillation, cardioversion, automatic implantable cardioverter-defibrillator [AICD], pacing, automated external defibrillator [AED]) safe at any stage of pregnancy; when performing chest compressions in second half of pregnancy, move hands up 1 to 2 interspaces to avoid fundus; gravid uterus on top of inferior vena cava decreases cardiac output and venous return by 30%; original recommendation to tip patient’s hip and lay her on her side; in decubitus position, only 80% of force of compressions transmitted; optimal position for chest compressions supine, with another rescuer manually deflecting uterus; perimortem cesarean section  —  misnomer (should be termed perimortem fetal extrication); guidelines say that if unable to recover pulses within 4 min with cardiopulmonary resuscitation (CPR), start extrication; studies show that best chances of maternal and fe­tal survival seen if able to remove fetus within 5 or 6 min; by removing fetus, maternal cardiac input and output im­proved by £80%; guidelines still recommend that if fundal height >23 cm, regardless of fetal viability, necessary to perform fetal extrication for best chance of maternal survival; fundal height 3 cm above umbilicus correlates to ges­tational age of »23 wk, and fetal extrication necessary if no return of spontaneous circulation

Chest compressions: history  —  in 1700s, patient vigorously rolled back and forth over blankets and pillows to pre­sumably produce forward cardiac flow (Marshall Hall’s method; found ineffective); in early 1800s, vigorous com­pression on upper abdomen (Howard’s method; presently called abdominal counterpulsation) found ineffective; in mid-1800s, Schafer’s method (patient in prone position and low back vigorously compressed); in late 1800s to early 1900s, barrel method (patient vigorously rolled back and forth over barrel) used and found ineffective; inver­sion method (patient hooked up by feet and hoisted up and down over tree) popular in early 1900s; horse method also used in early 1900s (patient placed over horse and galloped around); in 1980s, toilet plunger method studied and found ineffective; rate of compression  —  goal to perform 100 times/min; studies show that survival decreases as compression rate decreases; 1.5 to 2 in of depth ideal; in 2-person CPR, 30 chest compressions to every 2 rescue breaths recommended; 50:2 ratio shown even better, although size of studies inadequate; studies also show that for first 10 to 15 min of CPR, airway maneuvers should be avoided (cardiocerebral resuscitation); if bagging patient, should perform very slowly; rapid defibrillation best method; new motto from AHA “push hard, push fast”; speaker would add “don’t stop”; biggest problem interruptions in chest compressions (associated with mortality)

Cooling patient: therapeutic hypothermia  —  easy, inexpensive, saves lives, and associated with favorable neurologic outcome; original studies looked at victims of ventricular fibrillation arrest who recovered pulses, and upon ar­rival at hospital, had spontaneous circulation but still unconscious; used for any rhythm if patient recovers from primary cardiac arrest; most recent literature indicates that post-MI patient in cardiac arrest should receive ther­apeutic hypothermia before, during, and after catheterization; efficacy and safety good, with no increase in door-to-balloon time and coagulopathy and better neurologic outcome; obtained by placing ice bags on groin, neck, and axilla to achieve cooling of 1°/hr; adding cool IV fluids (4°C) hastens cooling; no standard about how fast to cool, as long as cooling initiated; invasive methods not recommended; if patient shivers, heat regenerated, so paralyze and intubate patient to avoid shivering; goal temperature low 90s°F or low 30s°C; below goal temperature, may in­duce coagulopathies and increase risk for infection; not indicated in pregnancy and cardiogenic shock; must con­tinue for 12 to 18 hr before gradual warm-up

Trendelenburg position: found ineffective for shock in 4 studies; for patient in shock, only displacing 2% of total blood volume back to heart, lungs, and brain; may decrease cardiac output, induce right ventricular stress, and af­fect pulmonary function

Defibrillation: study showed no difference in outcome between monophasic and biphasic defibrillators; escalating dosages of joules (J) ineffective; multiple shocks given rapidly no better than giving single shock each time; for ventricular fibrillation or pulseless ventricular tachycardia, start at maximum joules and stay at maximum (360 J for monophasic defibrillator, 120 or 200 J for biphasic); if time of cardiac arrest unknown, perform chest compressions for 2 min before applying first shock; immediately after giving first shock, resume chest compressions to minimize interruptions; overall goal to increase compressions and minimize interruptions; if using biphasic defibrillator, may continue chest compressions during application of  shock if using precoated gel pads; amount of current that goes into rescuer while shock given below threshold of human perception

Case: woman, 56 yr of age, presents with history of breast cancer; complains of chest pain and shortness of breath (SOB); afebrile, tachycardic, and tachypneic, with stable BP; clear lungs with some jugular venous distention (common with large PE); pulse oximetry normal; no evidence of acute MI on ECG; diagnosis PE; also consider large pericardial effusion (similar presentation to large PE)

PE and pericardial effusion: history and risk factors often similar; both tend to present with SOB, tachycardia, and tachypnea; ill-looking appearance seen in both; in severe cases, both conditions may go into cardiac arrest with ini­tial rhythm of PEA; treatments diametrically opposed  —  for PE, anticoagulants and thrombolytics; thrombolytics or heparin given in pericardial effusion cause progression to hemorrhagic tamponade; pericardiocentesis in patient mistakenly diagnosed with pericardial effusion (instead of PE) can lead to rupture of normal lung; bedside US or echocardiography  —  large effusion and PE not difficult to find; patients with large PE often present with massively distended right ventricle (RV) due to obstruction of right-to-left flow; pearls and pitfalls of large pericardial effusions  —  SOB not due to problem with alveoli, but due to fluid around bronchial structures that results in subjec­tive sense of SOB; also due to compromised ventricular function if present; massive cardiomegaly also seen; on ECG, combination of tachycardia and low voltage indicative of large pericardial effusion; give fluid (patients fluid-dependent); beware of intubation (eliminates preload that patient needs and drops venous return); positive pressure ventilation induces bradyasystolic arrest; PE  —  worsens when patient given fluid because of excess preload; giving fluids distends RV even more, pushing septum into LV which decreases in size, leading to decrease in LV filling, cardiac output, and BP; administer vasopressors early; BP improves with intubation due to removal of fluid from RV; pearl  —  T wave inversion in inferior and anteroseptal leads simultaneously on ECG >90% specific for PE; thrombolytics sometimes indicated in hypotensive patient with massively distended RV

Summary of treatments: antiarrhythmics, including amiodarone, ineffective and not shown to improve survival to hospital discharge; vasopressors also ineffective; only effective practices and methods include efficient chest com­pressions, ice, and electrical impulses delivered rapidly; avoid hyperthermia and hyperglycemia

Acknowledgements

Dr. Mattu was recorded at High Risk Emergency Medicine, held May 26-28, 2010, in San Francisco, CA, and sponsored by the Emergency Department at San Francisco General Hospital and Department of Emergency Medicine, University of Cali­fornia, San Francisco, School of Medicine. The Audio-Digest Foundation thanks Dr. Mattu and the sponsors for their coop­eration in the production of this program.

To attend the next High Risk Emergency Medicine meeting in person, visit www.HighRiskEM.com.

Suggested Reading

Aufderheide TP, Lurie KG: Death by hyperventilation: a common and life-threatening problem during cardiopulmonary resuscitation. Crit Care Med, 2004 Sep;32(9 Suppl):S345-51; Bernard S: Hypothermia after cardiac arrest: expanding the therapeutic scope. Crit Care Med, 2009 Jul;37(7 Suppl):S227-33; Bobrow BJ et al: Minimally interrupted cardiac resusci­tation by emergency medical services for out-of-hospital cardiac arrest. JAMA, 2008 Mar 12;299(10):1158-65; Dijkman A: Cardiac arrest in pregnancy: increasing use of perimortem caesarean section due to emergency skills training? BJOG, 2010 Feb;117(3):282-7; Kucher N et al: Massive pulmonary embolism. Circulation, 2006 Jan 31;113(4):577-82; Kudenchuk PJ et al: Transthoracic incremental monophasic versus biphasic defibrillation by emergency responders (TIMBER): a ran­domized comparison of monophasic with biphasic waveform ascending energy defibrillation for the resuscitation of out-of-hospital cardiac arrest due to ventricular fibrillation. Circulation, 2006 Nov 7;114(19):2010-8; Lockey AS, Nolan JP: Car­diopulmonary resuscitation in adults. Revised guidelines are more evidence based. BMJ, 2001 Oct 13;323(7317):819-20; Pepe PE et al: American Heart Association; International Liaison Committee on Resuscitation. Action sequence for lay person cardiopulmonary resuscitation. Ann Emerg Med, 2001 Apr;37(4 Suppl):S17-25; Sayre MR et al: American Heart Association Emergency Cardiovascular Care Committee. Hands-only (compression-only) cardiopulmonary resuscitation: a call to action for bystander response to adults who experience out-of-hospital sudden cardiac arrest: a science advisory for the public from the American Heart Association Emergency Cardiovascular Care Committee. Circulation, 2008 Apr 22;117(16):2162-7; Valenzuela TD et al: Interruptions of chest compressions during emergency medical systems resuscita­tion. Circulation, 2005 Aug 30;112(9):1259-65.