Report by
D G Markhorst, Paediatric Intensive Care Unit, Vrije Universiteit Medical Center, Amsterdam, The Netherlands; dg.markhorst@vumc.nl
M C J Kneyber, Paediatric Intensive Care Unit, Vrije Universiteit Medical Center, Amsterdam, The Netherlands
Joseph, a 4‐year‐old boy with septic shock, lactic acidosis and multi‐organ failure has been admitted to the paediatric intensive care unit. Mechanical ventilation, vaso‐active support and renal replacement therapy (CVVHD) are initiated. His haemoglobin level is 8.8 g/dl (5.5 mmol/l).
The senior consultant decides to order a red cell transfusion in order to optimise oxygen delivery, but the junior fellow argues that there is no evidence that transfusion improves outcome and that it may potentially be harmful.
Structured clinical question
In critically ill children [patient] does red cell transfusion to normal haemoglobin levels [intervention] improve survival and reduce incidence of complications or duration of mechanical ventilation [outcome]?
Search strategy and outcome
Secondary (Cochrane Library) and primary (PubMed) sources were included in the search.
Secondary sources: Search strategy: ((“Intensive Care” [MeSH]) OR (“Critical Care” [MeSH]) OR (“Critical Illness” [MeSH])) AND ((“Blood Transfusion” [MeSH]) OR (“Erythrocyte Transfusion” [MeSH])) AND systematic: five references, not related to the question.
Primary sources: Search strategy: ((“Intensive Care” [MeSH]) OR (“Critical Care” [MeSH]) OR (“Critical Illness” [MeSH])) AND ((“Blood Transfusion” [MeSH]) OR (“Erythrocyte Transfusion” [MeSH])): 548 references, five relevant to the question.1–5 See table 2.
Table 2 Should critically ill patients be routinely transfused to a normal haemoglobin level?
| Citation | Study group | Level of evidence | Outcome | Key results (95% CI) | Comments |
|---|---|---|---|---|---|
| Vincent et al | Adult ICU patients, | Prospective, | Mortality | Relative risk reduction (RRR) | Study limited to adults. No data |
| (2002)1 | n = 3534, | multicentre | −99% (95% CI: −121 to −78%) | presented on complication rate. | |
| transfused 1307, | observational | Absolute risk reduction (ARR): | Significant association between | ||
| not transfused 2227 | study (level 2) | −0.13 (−0.15 to 0.1) | degree of multi‐organ failure | ||
| Number needed to harm | (SOFA rate) and transfusion | ||||
| (NNH): 8 (7 to 10) | rates, favouring non‐ | ||||
| transfusion | |||||
| Corwin et al | Adult ICU patients, | Prospective, | Mortality and | Mortality: | Study limited to adults |
| (2004)2 | n = 4892, | multicentre | complications | RRR −38% (−54 to −23%) | |
| transfused 2152, | observational | ARR: −0.05 (−0.07 to −0.02) | |||
| not transfused 2740 | study (level 2) | NNH: 20 (14 to 34) | |||
| Complications: | |||||
| RRR: −165% (−179 to −151%) | |||||
| ARR: −0.30 (−0.33 to −0.28) | |||||
| NNH: 3 (3 to 4) | |||||
| Taylor et al | Adult ICU patients, | Prospective, single | Mortality and | Mortality: | Study limited to adults |
| (2006)3 | n = 2085, | centre observational | nosocomial | RRR −116% (−156 to −75%) | |
| transfused 449, | study (level 2) | infection rate | ARR: −0.12 (−0.16 to −0.08) | ||
| not transfused 1636 | NNH: 9 (6 to 13) | ||||
| Infections: | |||||
| RRR: −131% (−188 to −73%) | |||||
| ARR: −0.08 (−0.11 to 0.04) | |||||
| NNH: 13 (9 to 23) | |||||
| Hébert et al | Ventilated adult ICU | Randomised | Duration of | Mean duration of ventilation: | Study limited to adults, |
| (2001)4 | patients, n = 713, | controlled study | mechanical | 8.3±8.1 days in both groups | not designed and |
| restrictive transfusion | (level 2) | ventilation | (NS) | underpowered for this | |
| strategy 357, liberal | question | ||||
| strategy 356 | |||||
| Goodman et al | Critically ill anaemic | Retrospective, | Days of oxygen | Transfusion group had a longer | Paediatric multicentre study, |
| (2003)5 | (Hb⩽9 g/dl) children, | multicentre cohort | use, ventilator | duration of supplemental oxygen | using a restrictive transfusion |
| n = 240, | analysis (level 2) | days, length of | use (8±10 days vs 4±7 days; | protocol with a threshold of | |
| transfused 131, | stay | p<0.001), longer mechanical | 9 g/dl | ||
| not transfused 109 | ventilation (6±9 days vs | ||||
| 2±4 days; p<0.05), and | |||||
| longer ICU stay (9±10 days | |||||
| vs 6±9 days; p<0.001) |
Clinical bottom line
Blood cell transfusion is an independent risk factor for mortality in critically ill adult patients. (Grade B)
Blood cell transfusion is an independent risk factor for morbidity, including nosocomial infection and pulmonary oedema, in critically ill adult patients. (Grade B)
So far, mortality data are limited to adult studies. Given the significant negative effects on mortality and morbidity, there is no support for liberal red blood cell transfusion in critically ill paediatric patients. (Grade C)
Commentary
Anaemia is common among critically ill patients and may have multiple causes. Historically, expert opinion was that haemoglobin (Hb) concentrations should be maintained at levels of at least 10 g/dl (6 mmol/l) to maintain oxygen delivery. Transfusion decisions tend to be driven by individual transfusion triggers rather than by specific physiological triggers or consensus. In paediatric ICU patients, reported transfusion frequencies range up to 30%.6 After careful review of the literature, we found that available reports do not advocate liberal transfusion of red blood cells in critically ill patients. Evidently, critically ill patients are at increased risk of death whether or not transfusions are prescribed. Three studies in adult patients, corrected for predicted risk of mortality, found transfusion to be an independent risk factor. Based on these three studies, the number needed to harm (for death) is 14 (95% CI: 12 to 17). There is also evidence suggesting that red blood cell transfusions are associated with complications including pulmonary oedema4 and nosocomial infection.3
So far, mortality data are limited to adult studies. In the absence of further data, the decision to transfuse critically ill paediatric patients should be individualised and restricted to patients with Hb levels ⩽9 g/dl (5.6 mmol/l) or even lower.
References
- 1.Vincent J L, Baron J, Reinhart K.et al Anemia and blood transfusion in critically ill patients. JAMA 2002;288:1499-1507. [DOI] [PubMed] [Google Scholar]
- 2.Corwin H L, Gettinger A, Pearl R G.et al The CRIT study: anemia and blood transfusion in the critically ill. Crit Care Med 2004;32:39-52. [DOI] [PubMed] [Google Scholar]
- 3.Taylor R W, O'Brien J, Trottier J.et al Red blood cell transfusions and nosocomial infections in critically ill patients. Crit Care Med 2006;34:2302-8. [DOI] [PubMed] [Google Scholar]
- 4.Hébert P C, Blajchman M A, Cook D J.et al Do blood transfusions improve outcomes related to mechanical ventilation? Chest 2001;119:1850-7. [DOI] [PubMed] [Google Scholar]
- 5.Goodman A M, Pollack M M, Patel K M.et al Pediatric red blood cell transfusions increase resource use. J Pediatr 2003;142:123-7. [DOI] [PubMed] [Google Scholar]
- 6.Weldon B C, Conner D, Walther W J. Red blood cell transfusion practice in critically ill children. Anesthesiology 2004;101:A1468. [Google Scholar]