Association between relative anemia and early functional recovery after severe traumatic brain injury (TBI). Neurocrit Care 2016

Carr KR, Rodriguez M, Ottesen A, Michalek J, Son C, Pate V, et al. Association between relative anemia and early functional recovery after severe traumatic brain injury (TBI). Neurocrit Care 2016 [Epub ahead of print].

Severe traumatic brain injury (TBI) has a high risk of secondary injury owing to multi-system response and changes in metabolic demand. Therefore, they mandate resuscitation to maintain optimum oxygenation. Anaemia is quite common in critically ill patients, and the likelihood of blood transfusion increases in critically ill trauma patients.[1] The authors planned this retrospective cohort study with a view to illustrating a suitable transfusion threshold in a comparable subgroup of severe TBI population, which correlates to the most favourable early functional recovery, while defining severe TBI as those requiring ventriculostomies or intracranial pressure monitor placement. In a level 1 trauma facility institution, electronic medical records of patients between January 2011 and December 2013 were retrieved and studied. Patients above 18 years with a primary diagnosis of TBI were included in the study. Patients with other primary systemic injuries, requiring emergent non-neurosurgical intervention within 48 h of admission, patients who died within 48 h of admission, penetrating head trauma and admission Glasgow coma scale (GCS) score >8 were excluded from the study. All patients included had their GCS scores recorded on admission and upon discharge from the Intensive Care Unit (ICU) and hospital, respectively. Patients were transfused if haemoglobin (Hb) concentration fell below 7 g/dL as recommended by the Society of Critical Care Medicine[2] or in the case of acute active haemorrhage, ischaemia or if clinically needed. Increased intracranial pressures were treated on the basis of TBI management guidelines.[3] Clinical improvement which was defined as mean change in GCS of either 3 or 4 points compared to baseline score was assessed according to different haemoglobin transfusion thresholds: Hb ≤7 g/dL, Hgb ≤8 g/dL, Hb ≤9 g/dL, Hb ≤ 10 g/dL and Hb ≥10 g/dL. A total of 3923 patients were included, of which 89 patients had a primary admission diagnosis of TBI requiring either ICPM or ventriculostomy.

While comparing transfused versus non-transfused cohorts, there was no statistically significant difference in their baseline clinical status; 40% of the transfused patients underwent ventriculostomy compared to 60% in the non-transfused cohort. Forty per cent of the transfused patients required surgical decompression compared to 36% of the non-transfused admissions. In total, 36 patients received ventriculostomies and 53 patients received ICPMs, while 34 patients required decompressive craniotomies. The overall mortality rate was 16.85% and only 6 (6.74%) patients were discharged to home after hospitalisation. In assessing clinical improvement defined by change in GCS scores, the authors’ findings failed to demonstrate any association between either baseline Hb thresholds or transfusion status on clinically significant improvement. Secondarily, there was no mortality benefit associated with red blood cell (RBC) transfusions in this cohort. Of significance was the observation that patients with baseline Hb concentrations of 8 or 9 mg/dL were associated with decreased ICU hospitalisations. A study done by Sekhon et al. suggested an increased mortality in TBI patients with over a week mean haemoglobin concentration of <90 g/L.[4] In Transfusion Requirements in Critical Care trial,[5] 30-day mortality was recorded as 13% versus 17% for the liberal (transfusion threshold 7 g/dl) and restrictive groups (transfusion threshold 10 g/dl), respectively. However, in their report, length of stay for ICU and hospital admissions was not significantly different between both groups. Al-Dorzi et al. in their retrospective study identified that though anaemia was correlated to worse patient outcomes in patients with isolated TBI, packed RBC transfusion was independently associated with hospital mortality.[6]

The important limitation of this study was that the study being conducted in a single centre having level 1 trauma facility and small sample size findings may have differed in centres with different management protocols. In addition, advanced neuromonitoring such as tissue oxygenation to guide treatment strategies were lacking. Another important limitation was the use of GCS as scoring system as patients with non-verbal response at discharge may show less than expected clinical recovery.

The authors finally concluded that keeping specific Hb goal or transfusion threshold in severe TBI which required ventriculostomy/ICPM placement has no clinical benefits and does not decrease mortality, although keeping Hb in higher range can decrease ICU and hospital stay.

No conflict of interest has been declared by the author(s).

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