The incidence and significance of bacteremia in out of hospital cardiac arrest

Abstract

Background: The most common etiology of cardiac arrest is presumed of myocardial origin. Recent retrospective studies indicate that preexisting pneumonia, a form of sepsis, is frequent in patients who decompensate with abrupt cardiac arrest without preceding signs of septic shock, respiratory failure or severe metabolic disorders shortly after hospitalization. The contribution of pre-existing infection on pre and post cardiac arrest events remains unknown and has not been studied in a prospective fashion. We sought to examine the incidence of pre-existing infection in out-of hospital cardiac arrest (OHCA) and assess characteristics associated with bacteremia, the goal standard for presence of infection.

Methods and results: We prospectively observed 250 OHCA adult patients who presented to the Emergency Department (ED) between 2007 and 2009 to an urban academic teaching institution. Bacteremia was defined as one positive blood culture with non-skin flora bacteria or two positive blood cultures with skin flora bacteria. 77 met pre-defined exclusion criteria. Of the 173 OHCA adults, 65 (38%) were found to be bacteremic with asystole and PEA as the most common presenting rhythms. Mortality in the ED was significantly higher in bacteremic OHCA (75.4%) compared to non-bacteremic OHCA (60.2%, p<0.05). After adjustment for potential confounders, predictive factors associated with bacteremic OHCA were lower initial arterial pH, higher lactate, WBC, BUN and creatinine.

Conclusions: Over one-third of OHCA adults were bacteremic upon presentation. These patients have greater hemodynamic instability and significantly increased short-term mortality. Further studies are warranted to address the epidemiology of infection as possible cause of cardiac arrest.

Keywords: ACLS; Bacteremia; CVC; CVP; Cardiac arrest; DO(2); ED; EGDT; Emergency Department; FiO(2); GPU; ICU; IHCA; Infection; MAP; MET; MSOF; OHCA; PaO(2); SAPS II; SBP; SOFA; SSC; ScvO(2); Septic shock; SvO(2); VO(2); advanced cardiac life support; central venous catheterization; central venous oxygen saturation (%); central venous pressure (mmHg); early goal directed therapy; fraction of inspired oxygen (%); general practice unit; in-hospital cardiac arrest; intensive care unit; mean arterial pressure (mmHg); medical emergency teams; mixed venous oxygen saturation (%); multi-system organ failure; out of hospital cardiac arrest; partial pressure of arterial oxygen (mmHg); sequential organ failure assessment; simplified acute physiologic score; surviving sepsis campaign; systemic oxygen consumption; systemic oxygen delivery (mL/min/m(2)); systolic blood pressure (mmHg).