Clinical significance of thiopentone binding to haemoglobin and plasma protein.

The minimum dose of thiopentone required to induce anaesthesia was determined by giving thiopentone incrementally until verbal counting and eyelash reflexes were abolished. Males required 2.75 mg/kg (±0.11 SE) and females 2.16 mg/kg ( + 0.10 SE) to abolish verbal counting. Thiopentone requirement correlated positively with haemoglobin concentration (P<0.001) but not with plasma albumin, Ol globulin, total globulin or A/G ratio. The presence of sickle-cell haemoglobins did not influence thiopentone requirements. It is suggested that this result may have clinical importance.