Several studies have demonstrated that pre-operative fasting may be as short as 2 h for clear fluids and 6 h for solids with no adverse effect on volume or pH of gastric contents. Other studies suggest that many patients do not receive pre-operative prescribed medications. One hundred and fifty-three adults presenting for elective surgery (mean age 51 years) were studied to assess fasting practice. Fasting times far in excess of the recommended safe minimum were found. Mean length of fast for solids was 15 h 24 min (95% confidence intervals±49 min) and for fluids 12 h 30 min (95% confidence intervals±30 min). Of the 53 patients taking regular medications, 23 did not receive one or more drugs pre-operatively; most notably 45% of cardiac prescriptions were not administered. Despite strong evidence to support a change, actual practice continues to fall below accepted standards.

Combined effects of prolonged prostaglandin E1 (PGE1)-induced hypotension and haemodilution on hepatic function were studied in 30 patients undergoing hip surgery. The patients were randomly allocated to one of three groups; those in group A (n = 10) were subjected to controlled hypotension alone, those in group B (n = 10) to haemodilution alone and those in group C (n = 10) to both controlled hypotension and haemodilution. Haemodilution in groups B and C was produced by withdrawing approximately 1000 mL of blood and replacing it with the same amount of dextran solution, and final haematocrit values were 21 or 22%. Controlled hypotension in groups A and C was induced with PGE1 to maintain mean arterial blood pressure at 55mmHg for 180 min. Measurements included arterial ketone body ratio (AKBR, aceto-acetate/3-hydroxybutyrate) and clinical hepatic function parameters. AKBR and biological hepatic function tests showed no change throughout the time course in groups A and B. In group C, AKBR showed a significant decrease at 120 min (−40%) and at 180 min (−49%) after the start of hypotension and at 60 min (−32%) after recovery of normotension, and SGOT, SGPT, LDH and total bilirubin showed significant increases after operation. The results suggest that a prolonged combination of more than 120 min of PGE1-induced hypotension and moderate haemodilution would cause impairment of hepatic function.