Letter to the Editor

Excerpt

Engquist et al. [1] evaluated the effect of HHH therapy on global and regional cortical cerebral blood flow (CBF), measured using xenon CT in twenty subarachnoid hemorrhage (SAH) patients. They studied those with severe SAH and delayed cerebral ischemia (DCI) who were sedated and ventilated and employed a HHH protocol comprising predominantly volume expansion (dextran and albumin) without a significant component of induced hypertension. In fact, mean arterial pressure (MAP) was no higher during HHH therapy than at the time of the baseline study. In contrast, hematocrit was significantly reduced (from 36.4 to 31.7%). They acknowledge limitations of their methodology: for example, since the two studies were approximately 2 days apart, the causal relationship between HHH therapy and CBF changes cannot be precisely confirmed. Nonetheless, from their findings they draw two main conclusions: their modified version of HHH therapy (essentially hypervolemic hemodilution without induced hypertension) improves cerebral perfusion and volume expansion is likely responsible for this proposed benefit. …