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Hemoglobin levels and transfusions in neurocritically ill patients: a systematic review of comparative studies

Philippe Desjardins1, Alexis F Turgeon12*, Marie-Hélène Tremblay1, François Lauzier123, Ryan Zarychanski4, Amélie Boutin2, Lynne Moore25, Lauralyn A McIntyre67, Shane W English6, Andrea Rigamonti8, Jacques Lacroix9 and Dean A Fergusson7

Author Affiliations

1 Department of Anesthesiology, Division of Critical Care Medicine, Faculty of Medicine, Université Laval, 1050, Avenue de la Médecine, Pavillon Ferdinand-Vandry, Québec, QC, G1V 0A6, Canada

2 Centre de Recherche FRQ-S du Centre hospitalier affilié universitaire de Québec (CHA), Hôpital de l'Enfant-Jésus, (CHA-Research Center, Enfant-Jésus Hospital), Traumatologie - Urgence - Soins Intensifs (Trauma - Emergency - Critical Care Medicine), Université Laval, 1401, 18e rue, Québec, QC, G1J 1Z4, Canada

3 Department of Medicine, Faculty of Medicine, Université Laval, 1050, Avenue de la Médecine, Pavillon Ferdinand-Vandry, Québec, QC, G1V 0A6, Canada

4 Department of Internal Medicine, Sections of Critical Care Medicine, of Haematology and of Medical Oncology, Faculty of Medicine, University of Manitoba, Room GC425, Health Sciences Centre, 820 Sherbrook Street, Winnipeg, MB, R3T 2N2, Canada

5 Department of Social and Preventive Medicine, Faculty of Medicine, Université Laval, 1050, Avenue de la Médecine, Pavillon Ferdinand-Vandry, Québec, QC, G1V 0A6, Canada

6 Department of Medicine, Division of Critical Care, Faculty of Medicine, University of Ottawa, 501 Smyth Road, Ottawa, ON, K1H 8L6, Canada

7 Clinical Epidemiology Unit, Ottawa Hospital Research Institute, 501 Smyth Road, Ottawa, ON, K1H 8L6, Canada

8 Departments of Anaesthesia and Critical Care Medicine, Faculty of Medicine, University of Toronto, 30 Bond Street, Toronto, ON, M5B 1W8, Canada

9 Department of Pediatrics, Critical Care Medicine, Faculty of Medicine, Université de Montréal, 3175, Chemin Côte Sainte-Catherine, Montréal, QC, H3T 1C5, Canada

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Critical Care 2012, 16:R54  doi:10.1186/cc11293

Published: 2 April 2012

Abstract

Introduction

Accumulating evidence suggests that, in critically ill patients, a lower hemoglobin transfusion threshold is safe. However, the optimal hemoglobin level and associated transfusion threshold remain unknown in neurocritically ill patients.

Methods

We conducted a systematic review of comparative studies (randomized and nonrandomized) to evaluate the effect of hemoglobin levels on mortality, neurologic function, intensive care unit (ICU) and hospital length of stay, duration of mechanical ventilation, and multiple organ failure in adult and pediatric neurocritically ill patients. We searched MEDLINE, The Cochrane Central Register of Controlled Trials, Embase, Web of Knowledge, and Google Scholar. Studies focusing on any neurocritical care conditions were included. Data are presented by using odds ratios for dichotomous outcomes and mean differences for continuous outcomes.

Results

Among 4,310 retrieved records, six studies met inclusion criteria (n = 537). Four studies were conducted in traumatic brain injury (TBI), one in subarachnoid hemorrhage (SAH), and one in a mixed population of neurocritically ill patients. The minimal hemoglobin levels or transfusion thresholds ranged from 7 to 10 g/dl in the lower-Hb groups and from 9.3 to 11.5 g/dl in the higher-Hb groups. Three studies had a low risk of bias, and three had a high risk of bias. No effect was observed on mortality, duration of mechanical ventilation, or multiple organ failure. In studies reporting on length of stay (n = 4), one reported a significant shorter ICU stay (mean, -11.4 days (95% confidence interval, -16.1 to -6.7)), and one, a shorter hospital stay (mean, -5.7 days (-10.3 to -1.1)) in the lower-Hb groups, whereas the other two found no significant association.

Conclusions

We found insufficient evidence to confirm or refute a difference in effect between lower- and higher-Hb groups in neurocritically ill patients. Considering the lack of evidence regarding long-term neurologic functional outcomes and the high risk of bias of half the studies, no recommendation can be made regarding which hemoglobin level to target and which associated transfusion strategy (restrictive or liberal) to favor in neurocritically ill patients.