Infectious Complications in the Therapeutic Hypothermia Era

In This Article

Abstract and Introduction

Abstract

Objectives: Infectious complications are frequently reported in critically ill patients, especially after cardiac arrest. Recent and widespread use of therapeutic hypothermia has raised concerns about increased septic complications, but no specific reappraisal has been performed. We investigated the infectious complications in cardiac arrest survivors and assessed their impact on morbidity and long-term outcome.
Design: Retrospective review of a prospectively acquired intensive care unit database.
Setting: A 24-bed medical intensive care unit in a French university hospital.
Patients: Between March 2004 and March 2008, consecutive patients admitted for management of resuscitated out-of-hospital cardiac arrest were considered. Patients dying within 24 hrs were excluded. All patients' files were reviewed to assess the development of infection.
Interventions: None.
Measurements and Main Results: Of the 537 patients admitted after cardiac arrest, 421 were included and 281 patients (67%) presented 373 infectious complications. Pneumonia was the most frequent (318 episodes), followed by bloodstream infections (35 episodes) and catheter-related infections (11 episodes). When grouped together, Gram-negative bacteria were the most frequently isolated infectious germs (64%), but the main pathogen detected was Staphylococcus aureus (57 occurrences). Both application itself (83 vs. 73%; p = .02) and duration (1244 vs. 1176 mins; p = .05) of therapeutic hypothermia were significantly more frequent in infected patients. Infection was associated with increased mechanical ventilation duration (6 [2–9] vs. 3 [2–5.5] days; p < .001) and intensive care unit length of stay (7 [4–10] vs. 3 [2–7] days; p < .001). Nonetheless, there was no impact on intensive care unit mortality (174 [62%] vs. 92 [66%] patients; p = .45) or on favorable neurologic outcome (cerebral performance category 1–2, 102 [36%] vs. 47 [34%] patients; p = .58).
Conclusions: Infectious complications are frequent after cardiac arrest and may be even more frequent after therapeutic hypothermia. Despite increase in care costs, long-term and clinically relevant outcomes do not seem to be impaired. This should not discourage the use of therapeutic hypothermia in cardiac arrest survivors.

Introduction

Infection is a common complication in patients admitted to the intensive care unit (ICU); up to half of this population is concerned with subsequent morbidity and mortality.^[1] Survivors of cardiac arrest (CA), who represent a substantial part of the patients admitted to the ICU,^[2] are specifically concerned because they accumulate many infectious risks, mainly linked with emergency management, invasive procedures, ischemia-reperfusion–related immunodepression, and prolonged ICU stay. Previous studies have demonstrated that approximately half of prehospital survivors will have further septic manifestations develop, which are associated with increased mechanical ventilation duration and ICU length of stay.^[3,4] Furthermore, if therapeutic hypothermia has dramatically improved the neurologic outcome, then there are persistent experimental and clinical concerns about its impact on an increased incidence of infectious events.

Data about these patients' infectious complications are poor, with small and highly selected cohorts. They are also out-of-date, because they were published before the widespread use of therapeutic hypothermia.^[3–5] First, we conducted this study to examine incidence, sources, and pathogens of infectious complications in survivors of out-of-hospital CA (OHCA) managed since therapeutic hypothermia implementation. Second, we aimed at evaluating the impact of septic complications on outcome in this specific cohort of ICU patients.

Cite this: Infectious Complications in Out-of-hospital Cardiac Arrest Patients in the Therapeutic Hypothermia Era - Medscape - Jun 01, 2011.

Table 1. Baseline admission characteristics and outcome of patients admitted after cardiac arrest, classified according to the use of therapeutic hypothermia
	Therapeutic Hypothermia (n = 334)	No Therapeutic Hypothermia (n = 87)	p
Age, yr	60 (50–73)	60 (49–71)	.86
MacCabe score
0	288	69	.2
1–2	47	17
Male, n (%)	240 (72)	71 (82)	.08
Simplified Acute Physiology Score II	64 (56–75)	63 (53–77)	.41
No-flow (min)	5 (0–10)	3 (0–10)	.07
Low-flow (min)	15 (8–25)	10.5 (5–26)	.17
Shockable rhythm, n (%)	160 (48%)	40 (46%)	.75
Cardiac etiology, n (%)	209 (63%)	38 (44%)	.002^a
Postresuscitation shock, n (%)	180 (54%)	42 (49%)	.35
Infectious complication, n (%)	230 (69%)	51 (59%)	.03^a
Cerebral performance category 1–2, n (%)	120 (36%)	29 (33%)	.66
Intensive care unit mortality, n (%)	208 (62%)	58 (67%)	.45

Data are expressed as median (with interquartile range) or absolute value (%).
^aSignificant.

Table 2. Source of infections and causative agents in successfully resuscitated cardiac arrest patients
	Early-Onset Pneumonia	Late-Onset Pneumonia	Bloodstream Infection	Catheter-Related Infection	Abdominal Infection	Urinary Tract Infection	Sinusitis	Operative Site Infection	Total
Gram-positive bacteria
Staphylococcus aureus	42	8	6	1					57
Streptococcus pneumoniae	26	1	1						28
Streptococcus species	3		3				1		7
Staphylococcus epidermidis			3	3					6
Enterococcus faecalis			1		1	3			5
Clostridium difficile					2				2
Corynebacterium jeikeium			1						1
Gram-negative bacteria
Escherichia coli	28	10	8	3	1	1			51
Haemophilus influenzae and parainfluenzae	36	2		1			1		40
Klebsiella pneumoniae	13	3	1				1	1	19
Pseudomonas aeruginosa	5	11	2	1					19
Enterobacter cloacae	4	4	2		1				11
Proteus mirabilis	7	2	1						10
Moraxella catarrhalis	5								5
Acinetobacter baumannii		1							1
Stenotrophomonas maltophilia		1							1
Other enterobacteriaceae species	19	7	5	2					33
Others
Candida albicans			1						1
Polymorph flora	24								24
No growth	52								52
Total	264	50	35	11	5	4	3	1	373

Data are presented as number of episodes.

Table 3. Baseline admission characteristics and outcome of patients admitted for successfully resus-citated cardiac arrest, classified according to development or absence of infectious event during intensive care unit stay
	Patients With Infection (n = 281)	Patients Without Infection (n = 140)	p
Age, yr	60 (49–72)	60 (49–75)	.56
MacCabe score
0	243	114	.41
1–2	38	26
Male, n (%)	212 (75)	99 (71)	.3
Simplified Acute Physiology Score II	64 (55–76)	63 (55–75)	.78
No-flow (min)	5 (0–10)	5 (0–10)	.35
Low-flow (min)	15 (7–25)	15 (7–23)	.91
Shockable rhythm, n (%)	143 (51%)	57 (47%)	.05^a
Cardiac etiology, n (%)	175 (63%)	72 (51%)	.1
Therapeutic hypothermia, n (%)	232 (83%)	102 (73%)	.02^a
Hypothermia duration (min)	1244	1176	.05^a
Postresuscitation shock, n (%)	144 (51%)	78 (56%)	.39
Cerebral performance category 1–2, n (%)	102 (36%)	47 (34%)	.58
Intensive care unit mortality, n (%)	174 (62%)	92 (66%)	.45
Causes of death, n (%)
Brain damage with care withdrawal	112 (64%)	47 (51%)	.07
Postresuscitation multiorgan failure	28 (16%)	22 (23%)
Brain death	20 (11%)	18 (20%)
Others	14 (8%)	5 (6%)

Data are expressed as median (with interquartile range) or absolute value (%).
^aSignificant.

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