• Cardiac arrest is an abrupt cessation of cardiac pump function.
  • The four rhythms that produce pulseless cardiac arrest are ventricular fibrillation, pulseless ventricular tachycardia , asystole, and PEA



  • Usually due to underlying heart disease; ventricular fibrillation is the most common initial rhythm
  • PEA is continued electrical activity of the heart without effective mechanical contractions, and it often results from reversible causes that must be rapidly identified and treated. These are called the '5 Hs and 5 Ts':
  • Asystole is often a preterminal rhythm, and the rate of survival is extremely poor



Content 9


See: Loss of Responsiveness

Targeted temperature management (TTM)

In patients who remain comatose after a cardiac arrest. there no difference in neurological benefit or adverse effects at 72 hours, and again 6 months later, between those patients cooled to 33°C (approximately 90°F) as compared to those cooled to a near-normal 36°C (96°F). A large randomized, controlled trial of 939 patients published in the New England Journal of Medicine on December 5, 2013 ,

no patient in this study was allowed to have care withdrawn for an assumed 'poor neurologic prognosis' prior to the protocol's 72-hour post-arrest neuroprognostic evaluation, and further management was determined by results of the protocol's evaluation

The authors of an accompanying commentary expressed that 'modern, aggressive care that includes attention to temperature works, making survival more likely than death when a patient is hospitalized after CPR. In contrast to a decade ago, one half instead of one third of patients with return of spontaneous circulation after CPR can expect to survive hospitalization.' Methods to improve upon neurologic outcomes after cardiac arrest, particularly in hemodynamic optimization and early percutaneous coronary intervention, in addition to implementation of TTM, are being explored further.


Complications of Injecting Drug Use

  • Local problems—Abscess (Figures 240-2 
    Image not available.

    A 32-year-old woman with type 1 diabetes developed large abscesses all over her body secondary to injection of cocaine and heroin. Her back shows the large scars remaining after the healing of these abscesses. (Courtesy of ­Richard P. Usatine, MD.)

    and 240-3; Abscess), cellulitis, septic thrombophlebitis, local induration, necrotizing fasciitis, gas gangrene, pyomyositis, mycotic aneurysm, compartmental syndromes, and foreign bodies (e.g., broken needle parts) in local areas.2
    • IDUs are at higher risk of getting methicillin-resistant Staphylococcus aureus(MRSA) skin infections that the patient may think are spider bites (Figure 240-4).
    • Some IDUs give up trying to inject into their veins and put the cocaine directly into the skin. This causes local skin necrosis that produces round atrophic scars (Figure 240-5).
  • IDUs are at risk for contracting systemic infections, including HIV and hepatitis B or hepatitis C.
    • Injecting drug users are at risk of endocarditis, osteomyelitis (Figures 240-6and 240-7), and an abscess of the epidural region. These infections can lead to long hospitalizations for intravenous antibiotics. The endocarditis that occurs in IDUs involves the right-sided heart valves (see Chapter 50, Bacterial Endocarditis).2 They are also at risk of septic emboli to the lungs, group A β-hemolytic streptococcal septicemia, septic arthritis, and candidal and other fungal infections.


  • The outcome of patients experiencing cardiac arrest is poor.Aggregate survival to hospital discharge is less than 20% in most communities and hospital systems.2,3 The primary cause of mortality after cardiac arrest is primarily related to the effects of anoxic brain injury and not necessarily from cardiac complications. Among survivors, neurologic injury is common (present in up to 50% of survivors) and widely varied, ranging from subtle memory deficits to persistent vegetative state.4,5 






  • Morbidity and mortality rates are high; overall, it is estimated that between 5% and 10% of patients suffering out-of-hospital cardiac arrest survive to hospital discharge and only 20% of those are alive at 1 year.
  • Outcome is influenced by several factors, the most important of these being time from arrest to CPR and defibrillation. Other factors include the following:
    • Underlying rhythm: Patients with ventricular tachycardia and ventricular fibrillation have a better prognosis than those with asystole
    • Blood pressure on return of spontaneous circulation: Greater than 90 mm Hg systolic indicates a better chance of survival
    • Any coexisting cardiac or other disease
  • Survivors of out-of-hospital cardiac arrest are prone to ventricular arrhythmias in the first 24 to 48 hours following admission; these usually respond well to antiarrhythmic drugs

Outcomes differ based on initial rhythm found at scene of cardiac arrest. For example, outcomes are poorer with so-called “nonshockable” rhythms (asystole, pulseless electrical activity [PEA]) compared to “shockable” rhythms (ventricular tachycardia [VT] or ventricular fibrillation [VF]). Improved survival may be best when initial rhythm is VF, but still dependent on prompt delivery of effective CPR. Clinical factors identified as predictors of greater likelihood of survival to hospital discharge are witnessed arrest, VT or VF as initial rhythm, return to spontaneous circulation (ROSC) during first 10 minutes, and longer duration of overall resuscitation efforts.1


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