15 Apr 2013

http://reference.medscape.com/
    The 2010 American Heart Association (AHA) guidelines for basic life support (BLS) and advanced cardiac life support (ACLS) represent a departure from how most clinicians were trained. Image courtesy of Wikimedia Commons.
   Do you follow current, best practice for BLS and ACLS? Some of the significant recommendations include:
• Chest compressions as the first step in BLS -- a "C-A-B" (circulation, airway, breathing) approach, instead of the previous "A-B-C" formulation;
• Quantitative waveform capnography to evaluate and monitor advanced airway placement and ventilation;
• Updated indications for medications, including intravenous (IV) epinephrine for pulseless electrical activity (PEA) and asystole, chronotropic agents for symptomatic or unstable bradycardia, and adenosine for the assessment and treatment of stable, monomorphic, wide-complex tachycardia;
• Urgent cardiac catheterization and percutaneous coronary intervention (PCI) in cardiac arrest survivors with ST-segment elevation myocardial infarction; and
• Postresuscitation measures, such as therapeutic hypothermia to improve neurologic outcomes, and maintaining appropriate oxygen saturation and blood glucose to prevent multiorgan dysfunction.

   On rounds, you see an elderly man having an ECG who has collapsed and is unresponsive. The patient's telemetry (top strip of image shown) is abnormal. His 12-lead ECG (lower strips) is on the machine at bedside. Top strip of image shown courtesy of Wikimedia Commons.
   While you await the code team and equipment, which of the following should you perform first?
A. Open the patient's airway with a jaw-thrust or chin-tilt maneuver
B. Perform 2 rescue breaths, either mouth-to-mouth or using a mask with reservoir
C. Start chest compressions immediately at 100 compressions per minute
D. Pour ice on the patient to initiate hypothermic resuscitation

   Answer: C. Start chest compressions immediately at 100 compressions per minute
   The patient has had a cardiac arrest from ventricular fibrillation (VF). Defibrillation is the most appropriate treatment, but while awaiting the necessary equipment you should initiate high-quality chest compressions rather than spending time on advanced airway maneuvers, according to the AHA recommendations.
   The AHA recommends that a first responder to a code situation focus initially on calling for help, and then performing high-quality chest compressions. The new recommendations advise laypersons to focus on compression-only cardiopulmonary resuscitation (CPR). One reason for this change in emphasis is to encourage passersby, who may be reluctant to perform mouth-to-mouth breathing on a stranger, to provide high-quality CPR nevertheless.

   The 2010 AHA guidelines advise providers to perform compressions at a depth of at least 2 inches in adults, and at least one third of the chest diameter in children and infants. Providers must also ensure that there is complete chest recoil between compressions. In a study of VF/ventricular tachycardia (VT) arrests, minimizing interruptions in chest compressions was shown to improve outcome, including both return of spontaneous circulation and survival to hospital discharge. Pulse checks should be 10 seconds long at maximum.
   For adult resuscitations in all settings, the appropriate rate of chest compressions is at least 100 compressions per minute. Initial responders should begin with a pulse assessment, and then proceed to 100-beat-per-minute compressions. Image courtesy of Wikimedia Commons.

   In the 2005 ACLS guidelines, application of cricoid pressure was recommended for an unconscious patient when a third rescuer is available. In the 2010 guidelines, the AHA recommends against routine use of cricoid pressure. The guidelines cite 7 randomized trials showing that cricoid pressure delays advanced airway placement and does not prevent aspiration. Cricoid pressure may still be used during intubation if desired by the healthcare team

   The top strip shows a typical capnography waveform. Appropriate ventilation is shown on the lower left and hyperventilation on the lower right. Hyperventilation is not helpful during resuscitation for cardiac arrest and, in fact, could worsen cardiac output and thus outcome.
   Guidelines recommend use of quantitative waveform capnography to measure end-tidal carbon dioxide and provide easy confirmation of initial advanced airway placement. In addition, it provides continuous assessment of airway and ventilation. This can alert providers to otherwise undetected airway displacement during resuscitation and transport. Also, a sudden rise in end-tidal carbon dioxide during resuscitation is an independent marker of return of spontaneous circulation that can be noted without interrupting chest compressions.
   CPR-assistance devices such as the impedance threshold device and load-distributing band CPR are not recommended, as they have not been shown to improve outcomes. Images courtesy of Wikimedia Commons

   Your next patient was admitted with an apparent myocardial infarction. As you enter the room, he moans and slumps in bed. The patient is unresponsive and pulseless. The team immediately begins high-quality chest compressions while you obtain the rhythm strip from the monitor (shown). You identify it as PEA. Image courtesy of Wikimedia Commons.
   Which of the following should be administered to the patient?
A. Epinephrine
B. Atropine
C. Sodium bicarbonate
D. Calcium gluconate
E. All of the above

Answer: A. Epinephrine
   Give IV epinephrine at the dose for cardiac arrest. This is the mainstay of medical treatment for PEA and asystole (shown), though one should evaluate the patient quickly for any reversible causes. Although previous guidelines recommended atropine for routine treatment of PEA/asystole, it is no longer included in the PEA/asystole treatment algorithm.
   You are able to get a palpable pulse after 4 minutes of ACLS. However, the patient's rhythm strip continues to show the same tracing, and systolic blood pressure is only 75 mm Hg.
   Which of the following should be the next step?
A. Commence external pacing
B. Begin dopamine infusion
C. Begin epinephrine infusion
D. Any of the above is acceptable

Answer: D. Any of the above is acceptable
   External pacing or chronotropic agents (eg, dopamine, epinephrine) are all acceptable treatments for a symptomatic bradycardia. Atropine remains the initial treatment of choice for symptomatic or unstable bradycardia. However, IV infusion of chronotropic agents are now recommended as equally effective alternatives to transcutaneous pacing when atropine fails. Image courtesy of Wikimedia Commons.

   Your last patient on morning rounds was admitted the previous night for palpitations. As you approach the bedside, you note that the patient is sitting up in bed and appears flushed. He states that his palpitations are back. You observe the shown rhythm on the monitor, and you and the team's medical students discuss the various forms of wide-complex tachycardias. Image courtesy of Wikimedia Commons.
   Which of the following should you tell the students is indicated for this patient?
A. Lidocaine
B. Atropine
C. Adenosine
D. Epinephrine

Answer: C. Adenosine
   Other treatment options include amiodarone and electrical cardioversion. The indications for adenosine have been expanded. In the 2005 AHA guidelines, adenosine was recommended for stable, narrow-complex tachycardia consistent with supraventricular tachycardia, such as Wolff-Parkinson-White syndrome (shown). In the 2010 edition, adenosine is also indicated for the initial assessment and treatment of stable, monomorphic, wide-complex tachycardia with a regular rhythm. It should not be used in irregular tachycardia, such as atrial fibrillation.

   Improved neurologic outcomes have been found in response to therapeutic hypothermia. Most of the initial studies on therapeutic hypothermia were performed on patients who presented in VF or VT. Hypothermia should be initiated as soon as possible after the return of spontaneous circulation, with a target temperature of 32°C-34°C.

   This ECG shows evidence of an extensive inferior myocardial infarction. The 2010 AHA guidelines include recommendations in favor of urgent cardiac catheterization and PCI in cardiac arrest survivors who demonstrate ECG evidence of ST-segment elevation myocardial infarction, regardless of neurologic status. There is also increasing support for patients without ST-segment elevation on ECG who are suspected of having acute coronary syndrome (ACS) to receive urgent cardiac catheterization, including patients who present in VF or VT.

   A 75-year-old white man presents to the emergency department with 2 episodes of syncope. He has a history of hypertension, which is being treated with amlodipine, but he is otherwise on no other medications. On examination he is alert, oriented, and in no extreme distress. His blood pressure is 80/40 mm Hg with a heart rate of 50 beats per minute. During examination, he has a recurrent episode of syncope. His telemetry is shown. Image courtesy of Eric Yang, MD.
   While preparations are being made for placement of a temporary transvenous pacer, what should you emergently administer to the patient?
A. IV epinephrine bolus
B. IV dopamine drip
C. IV isoproterenol drip
D. IV atropine bolus

Answer: D. IV atropine bolus
   The guidelines call for use of atropine in patients with symptomatic bradycardia (heart rate approximately 43 bpm, with RR interval marked). While the new guidelines also recommend the use of IV chronotropic agents such as dopamine, epinephrine, and isoproterenol, atropine is still the first-line agent as it can be more quickly administered. In this particular case, given the hypotension, isoproterenol should not be used if an IV chronotropic agent is needed after atropine administration. Image courtesy of Eric Yang, MD

   The AHA "Key Objectives" of post-arrest care are shown. In addition to the use of therapeutic hypothermia, the need to treat ACS immediately, and other key objectives, the 2010 AHA guidelines emphasize treating and preventing multiorgan dysfunction. Specific suggestions for prevention of multiorgan dysfunction include avoiding hyperventilation and maintaining euglycemia. Multiple studies have shown improved outcomes when these parameters are maintained. Another specific new recommendation is to wean the arrest survivor's oxygen to maintain saturations between 94% and 99%, to prevent hyperoxygenation, which may be associated with poor outcomes

   In summary, changes in the 2010 AHA ACLS protocols include the following:
   Chest compressions at a rate of 100 per minute, with minimal interruptions, are now recommended as the first step in resuscitation -- a C-A-B approach, instead of the previous A-B-C formulation. Cricoid pressure does not prevent aspiration and may delay advanced airway placement.

   Quantitative waveform capnography provides an improved means to evaluate and monitor advanced airway placement and ventilation. CPR assistance devices have not been shown to improve outcome and are not recommended.

   IV epinephrine is recommended in place of atropine for the treatment of PEA and asystole. For symptomatic or unstable bradycardia that fails to respond to atropine, chronotropic agents may be considered as an alternative to pacing. Indications for adenosine now include the initial assessment and treatment of stable, monomorphic, wide-complex tachycardia with a regular rhythm


   Urgent cardiac catheterization and PCI are favored for cardiac arrest survivors who demonstrate ECG evidence of ST-segment elevation myocardial infarction, as well as for patients with ACS. Measures for postresuscitation care include therapeutic hypothermia to improve neurologic outcomes, and avoiding hyperventilation and maintaining euglycemia to prevent multiorgan dysfunction.
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