Volume kinetics of Ringer's solution during induction of spinal and general anaesthesia

Abstract

The kinetics of an i.v. infusion of 20 ml kg^–1 of Ringer’s solution over 60 min was studied in patients undergoing spinal (n=10) and general (n=10) anaesthesia. The induction resulted in similar changes in volume kinetic parameters in both groups. When a one‐volume model was employed (n=8), however, the infusion expanded a smaller body fluid space in the four patients who had received preoperative enteric lavage (3.3 vs 8.3 litres), which is consistent with hypovolaemia. When a two‐volume model was statistically justified (n=12), the induction reduced the rate of fluid equilibration between a fairly small central (V₁, mean 1.4 litres) and a peripheral body fluid space by about 50% (PBr J Anaesth 2001; 87: 406–14