Skip to main content

Table 3 Clinical studies assessing the impact of anemia or RBC transfusions on P bt O 2 and other physiologic parameters in brain-injured patients

From: Anemia and red blood cell transfusion in neurocritical care

Study

Patients

Design

Baseline

Intervention

Main findings

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%)

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%)

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)

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

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

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

* 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

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)

Chang and colleagues [237]

27 TBI

Retrospective

Not applicable

None

- 13.7% of PbtO2 readings <20 mmHg

- No significant association between PbtO2 and Hb

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

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)

Cruz and colleagues [240]

62 TBI

Retrospective (prospective data)

Not applicable

None

- Cerebral extraction of oxygen was highest when Hb <10 g/dl

  1. * published only as abstract.
  2. 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.