Additional colloids have only a minor haemodilutive effect after surgery for aneurysmal subarachnoid haemorrhage

Haemodilution is commonly used as prophylaxis, as well as treatment for cerebral ischaemia after aneurysmal subarachnoid haemorrhage (SAH). Thirty-six patients operated for aneurysmal SAH were evaluated retrospectively; 24 received haemodilutive therapy and 12 patients, as a control group, received no additional therapy. There was a 'spontaneous' drop in haematocrit by 22% in both groups, and a corresponding drop in haemoglobin by 23% in the treatment group and 19% in the non-haemodiluted group, during the first 4 days after the SAH. After the initial decrease the haematocrit remained stable between 0.28 and 0.33 until day 14 in both groups. The haemodilutive group had only a minor lower haematocrit level during days 8-12 as the additional fluid resulted in increased renal excretion. This minor difference was, however, significant (p < 0.02).