Table 3 |
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Clinical studies assessing the impact of anemia or RBC transfusions on PbtO2 and other physiologic parameters in brain-injured patients |
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|
Study |
Patients |
Design |
Baseline |
Intervention |
Main findings |
|
|
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|
Smith and colleagues [139] |
23 TBI 12 SAH |
Retrospective (prospective database) |
Hb = 8.7 g/dl PbtO2 = 24.4 mmHg |
Any RBC transfusion (number of units not specified a priori; 80% received ≥1 unit; mean Hb increased to 10.2 g/dl) General transfusion threshold Hb <10 g/dl or hct <30% (no protocol) |
- Mean increment in PbtO2 3.2 mmHg (15%) - Increment not related to baseline PbtO2 - PbtO2 decreased in 9/35 patients (26%) |
|
|
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|
Leal-Noval and colleagues [140] |
51 TBI |
Prospective observational |
Hb = 9.0 g/dl PbtO2 = 24.4 mmHg |
1 or 2 units RBCs (number of units not specified a priori; 52% received 2 units; mean Hb increased to 10.6 g/dl) General transfusion threshold Hb <10 g/dl (no protocol) |
- Mean increment in PbtO2 3.8 mmHg (16%) - Increment larger at lower baseline PbtO2 - PbtO2 decreased in 13/51 patients (25%) |
|
|
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|
Leal-Noval and colleagues [141] |
66 TBI (males) |
Prospective observational |
Hb = 8.9 g/dl PbtO2 = 21.3 to 26.2 mmHg |
1 or 2 units RBCs number of units not specified a priori; 59% received 2 units; mean Hb increased to 10.2 g/dl) General transfusion threshold Hb <9.5 g/dl (no protocol) |
- Newer units of blood (≤14 days) resulted in greater mean increment in PbtO2 (3.3 mmHg (16%) vs. 2.1 mmHg (8%)) - PbtO2 decreased only in patients receiving older blood (>19 days) |
|
|
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|
Zygun and colleagues [142] |
30 TBI |
Prospective RCT |
Hb = 8.2 g/dl PbtO2 = 18.8 mmHg |
Randomized to transfusion thresholds of 8, 9, or 10 g/dl; 2 units RBCs administered over 2 hours (mean Hb increased to 10.1 g/dl) |
- Mean increment in PbtO2 2.2 mmHg (12%) - Increment in PbtO2 most prominent when LPR >25 - PbtO2 decreased in 13/30 patients (43%) - No effect on SjvO2 or microdialysis parameters |
|
|
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|
Ekelund and colleagues [162] |
8 SAH (TCD-vaso-spasm) |
Prospective interventional |
Hb = 11.9 g/dl |
Isovolemic hemodilution (venesection with infusion of dextran 70 and 4% albumin) to mean Hb of 9.2 g/dl |
- Outcomes (using 133Xenon and SPECT): - Increased global CBF (52.3 to 58.6 ml/100 g/min) - Reduced cerebral vascular resistance - Reduced oxygen delivery - Increased ischemic brain volume |
|
|
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|
Muench and colleagues [163] |
10 SAH |
Prospective interventional |
Hb = 10.6 g/dl PbtO2 = 24.8 mmHg |
Volume expansion with HES ± crystalloid to achieve ITBVI >1000 ml/m2; this produced a decline in Hb of 1.3 to 2.0 g/dl (on various days) |
- Although hypervolemia/hemodilution produced a slight increment in CBF, PbtO2 decreased by an average of 0 to 5 mmHg - Only induced hypertension was consistently effective at raising PbtO2 |
|
|
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|
* Dhar and colleagues [164] |
8 SAH |
Prospective interventional |
Hb = 8.7 g/dl |
One unit RBCs (mean Hb increased to 9.9 g/dl) |
- Outcomes assessed using PET: - No significant change in CBF - Reduced O2 extraction ratio (49 to 41%; P = 0.06) - No significant change in CMRO2 - Reduction in oxygen extraction ratio observed also in territories with vasospasm and low oxygen delivery |
|
|
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|
Oddo and colleagues [165] |
20 SAH |
Retrospective (prospective database) |
Not applicable |
None |
- Hb <9 g/dl associated with higher risk of PbtO2 <20 mmHg (OR 7.2, P < 0.01) and LPR >40 (OR 4.2, P = 0.02) |
|
|
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|
Chang and colleagues [237] |
27 TBI |
Retrospective |
Not applicable |
None |
- 13.7% of PbtO2 readings <20 mmHg - No significant association between PbtO2 and Hb |
|
|
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|
Naidech and colleagues [238] |
6 SAH |
Prospective observational |
Not reported |
14 RBC transfusions (no protocol) |
- Hb correlated with cerebral oximetry (rO2) - rO2 increased following 11/14 transfusions, but not statistically significant |
|
|
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|
Sahuquillo and colleagues [239] |
28 TBI |
Prospective |
Not applicable |
None |
- Critical LOI (suggestive of ischemia/infarction) associated with lower Hb (11.7 g/dl vs. 13.1 g/dl) |
|
|
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|
Cruz and colleagues [240] |
62 TBI |
Retrospective (prospective data) |
Not applicable |
None |
- Cerebral extraction of oxygen was highest when Hb <10 g/dl |
|
|
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|
* published only as abstract. CBF = cerebral blood flow; CMRO2 = cerebral metabolic rate; Hb = hemoglobin; HES = hydroxyethyl starch; ITBVI = intrathoracic blood volume index; LOI = jugular venous lactate:oxygen index; LPR = lactate:pyruvate ratio; PbtO2 = brain tissue oxygen tension; PET = positron emission tomography; RBC = red blood cell; RCT = randomized controlled trial; rO2 = cerebral oximetry; SAH = subarachnoid hemorrhage; SjvO2 = jugular venous oxygen saturation; SPECT = single photon emission computed tomography; TBI = traumatic brain injury; TCD = transcranial Doppler. |
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Kramer and Zygun Critical Care 2009 13:R89 doi:10.1186/cc7916 |
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