Therapeutic benefits of mild hypothermia in patients successfully resuscitated from cardiac arrest:A meta-analysis

doi:10.5847/wjem.j.issn.1920-8642.2013.04.003

Abstract

Abstract:

BACKGROUND: Good neurological outcome after cardiac arrest (CA) is hard to achieve for clinicians. Experimental and clinical evidence suggests that therapeutic mild hypothermia is beneficial. This study aimed to assess the effectiveness and safety of therapeutic mild hypothermia in patients successfully resuscitated from CA using a meta-analysis.
METHODS: We searched the MEDLINE (1966 to April 2012), OVID (1980 to April 2012), EMBASE (1980 to April 2012), Chinese bio-medical literature & retrieval system (CBM) (1978 to April 2012), Chinese medical current contents (CMCC) (1995 to April 2012), and Chinese medical academic conference (CMAC) (1994 to April 2012). Studies were included if 1) the study design was a randomized controlled trial (RCT); 2) the study population included patients successfully resuscitated from CA, and received either standard post-resuscitation care with normothermia or mild hypothermia; 3) the study provided data on good neurologic outcome and survival to hospital discharge. Relative risk (RR) and 95% confidence interval (CI) were used to pool the effect.
RESULTS: The study included four RCTs with a total of 417 patients successfully resuscitated from CA. Compared to standard post-resuscitation care with normothermia, patients in the hypothermia group were more likely to have good neurologic outcome (RR=1.43, 95% CI 1.14-1.80, P=0.002) and were more likely to survive to hospital discharge (RR=1.32, 95% CI 1.08-1.63,P=0.008). There was no significant difference in adverse events between the normothermia and hypothermia groups (P>0.05), nor heterogeneity and publication bias.
CONCLUSION: Therapeutic mild hypothermia improves neurologic outcome and survival in patients successfully resuscitated from CA.

Key words: Cardiac arrest, Cardiopulmonary resuscitation, Return of spontaneous circulation, Mild hypothermia, Meta-analysis

Xiao-ping Wang, Qing-ming Lin, Shen Zhao, Shi-rong Lin, Feng Chen. Therapeutic benefits of mild hypothermia in patients successfully resuscitated from cardiac arrest:A meta-analysis[J]. World Journal of Emergency Medicine, 2013, 4(4): 260-265.

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Study	n	Setting	Rhythm	Etiology	Intervention	Neurological recovery [n/N (%)]		Survival to hospital discharge [n/N(%)]
Study	n	Setting	Rhythm	Etiology	Intervention	Mild hypothermia	Normo- thermia	Mild hypothermia	Normo- thermia
Bernard (2002)^[10]	77	Out-of-hospital	VF	Cardiac	Cooling with packs placed around the head, neck, torso, and limbs, target temperature of 33 °C, and duration of hypothermia for 12 h	21/43 (48.8)	9/34 (26.4)	21/43 (48.8)	11/34 (32.3)
HACA (2002)^[11]	273	In-hospital or out-of-hospital	VF or VT	Cardiac	Cooling with blanket, target temperature of 32 °C to 34 °C, and duration of hypothermia for 24 h	75/136 (55.1)	54/137 (39.4)	81/137 (59.1)	62/138 (44.9)
Hachimi-Idrissi (2001)^[12]	30	Out-of-hospital	AS	Cardiac	Cooling with helmet device, target temperature of 34 °C, and duration of hypothermia for 3 h	2/16 (12.5)	0/14 (0.0)	3/16 (18.7)	1/14 (7.1)
Kamarainen (2009)^[13]	37	Out-of-hospital	VF, PEA, or AS	Cardiac or non-cardiac	Cooling with intravenous infusion of 4 °CRinger's solution, target temperature of 33 °C, and an unknown duration of hypothermia	8/19 (42.1)	8/18 (44.4)	8/19 (42.1)	8/18 (44.4)

Study	Randomization	Blinding	Follow-up	Total
Bernard (2002)^[10]	1	2	1	4
HACA (2002)^[11]	2	2	1	5
Hachimi-Idrissi (2001)^[12]	2	2	1	5
Kamarainen (2009)^[13]	1	0	1	2

Adverse events	Study (n)	Patients (n)	RR (95% CI)	Pvalue
Pneumonia	1	272	1.27 [0.90-1.78]	0.17
Pulmonary edema	1	269	1.76 [0.61-5.12]	0.30
Bleeding	1	273	1.38 [0.88-2.16]	0.16
Need for platelet tansfusions	1	273	5.11 [0.25-105.47]	0.29
Sepsis	1	273	1.93 [0.89-4.18]	0.09
Arrhythmia or recurrence of cardiac arrest	2	310	1.10 [0.80-1.53]	0.55
Renal failure or oliguria	2	303	0.88 [0.48-1.61]	0.68
Hemodialysis	2	350	1.11 [0.41-3.01]	0.84
Pancreatitis	1	273	0.51 [0.05-6.57]	0.58
Seizures	1	269	0.89 [0.39-2.02]	0.78

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