Enflurane blood-gas solubility: influence of weight and hemoglobin

The blood-gas partition coefficient of enflurane was measured in nine nonobese and eight morbidity obese patients and correlated with weight, body mass index, and blood hemoglobin. The enflurane blood-gas partition coefficient was lower in the obese patients than in nonobese patients (mean +/- SEM: 2.03 +/- 0.02 versus 1.76 +/- 0.03, respectively, p less than 0.025). There was a negative correlation between enflurane blood solubility and both body mass index and weight (r = 0.59 and -0.55, respectively, p less than 0.01). A positive correlation was found between hemoglobin and the enflurane blood-gas partition coefficient (r = 0.69, p less than 0.01). Equilibrium between inspired and alveolar enflurane concentration should be faster in morbidity obese and anemic patients than in healthy, nonobese patients.