to developing sepsis. In addition, patients with indwelling lines, such as
Foley catheters, are at an even higher risk for infection.
Hypovolemic shock (a)occurs when there is inadequate volume in the
circulatory system, resulting in poor oxygen delivery to the tissues. Neuro-
genic shock (b)occurs after an acute spinal cord injury, which disrupts
sympathetic innervation resulting in hypotension and bradycardia. Cardio-
genic shock (c)is caused by decreased cardiac output producing inade-
quate tissue perfusion. Anaphylactic shock (d) is a severe systemic
hypersensitivity reaction resulting in hypotension and airway compromise.
199.The answer is b.(Rosen, pp 71-72.)The rhythm is VF.Along with
pulseless VT, these are nonperfusing rhythmsthat are treated identically
because it is thought to be caused by the same mechanisms. The earlier a
“shock” is administered in cardiac arrest, the more likely the patient will
return to spontaneous circulation with a perfusing rhythm. If there is a delay
to defibrillation (> 4 minutes), CPR should be administered for 60 to 90 sec-
onds before defibrillation. If after defibrillation (200 J biphasic or 360 J
monophasic) the patient’s rhythm is still VF or pulseless VT, then assisted
ventilation and chest compressions should be started. Intubation should be
performed and IV access obtained for the administration of epinephrine or
vasopressin. If the rhythm is unchanged after administration of vasopressor
therapy, then another attempt at defibrillation at 360 J (or 200 J biphasic)
with subsequent administration of an antidysrhythmic (eg, amiodarone) is
recommended. Of note, monophasic defibrillation delivers a charge in only
one direction. Biphasic defibrillation delivers a charge in one direction for
half of the shock and in the electrically opposite direction for the second
half. Biphasic defibrillation significantly decreases the energy necessary for
successful defibrillation and decreases the risk of myocardial damage.
(a)There is no role for observation with VF. Successful return of a
perfusing rhythm is most likely to result with immediate defibrillation.
(c)Synchronized cardioversion is energy delivered to match the QRS com-
plex.This reduces the chance that a shock will induce VF. Synchronization
is used to treat tachydysrhythmias (eg, rapid atrial fibrillation) in hemody-
namically unstable patients. It should not be used in VF or pulseless VT.
(d)The most beneficial intervention for this patient is immediate defibrilla-
tion. If this fails, the patient’s airway management (ABCs) will require him
to be intubated. (e)Amiodarone, an antidysrhythmic, is used in patients
with VF or pulseless VT after appropriate defibrillation and administration
of vasopressor therapy.
226 Emergency Medicine