Hyperventilation accelerates the rise of arterial blood concentrations of desflurane in gynecologic patients

Abstract

OBJECTIVES:Under a constant inspired concentration, the uptake of a volatile anesthetic into the arterial blood should mainly be governed by alveolar ventilation, according to the assumption that the patient's cardiac output remains stable during anesthesia. We investigated whether ventilation volume affects the rate of desflurane uptake by examining arterial blood concentrations.METHOD:Thirty female patients were randomly allocated into the following three groups: hyperventilation, normal ventilation and hypoventilation. Hemodynamic variables were measured using a Finometer, inspiratory and end-tidal concentrations of desflurane were measured by infrared analysis, and the desflurane concentration in the arterial blood (Ades) was analyzed by gas chromatography.RESULTS:During the first 10 minutes after the administration of desflurane, the Ades was highest in the hyperventilation group, and this value was significantly different from those obtained for the normal and hypoventilation groups. In addition, hyperventilation significantly increased the slope of Ades-over-time during the first 5 minutes compared with patients experiencing normal ventilation and hypoventilation, but there were no differences in these slopes during the periods from 5-10, 10-20 and 20-40 minutes after the administration of desflurane. This finding indicates that there were no differences in desflurane uptake between the three groups after the first 5 minutes within desflurane administration.CONCLUSIONS:Hyperventilation accelerated the rate of the rise in Ades following desflurane administration, which was time-dependent with respect to different alveolar ventilations levels.

Duration effect of desflurane anesthesia and its awakening time and arterial concentration in gynecologic patients

“…Prior to induction, 10 ml of blood was collected from each patient to determine the blood-gas partition coefficient (λ) of desflurane (8). In each blood sample, Desflurane was converted to the corresponding concentration, based on gas chromatographic measurements, and the blood-gas partition coefficient of desflurane (λ) was measured.…”

“…An integrator and a data acquisition system were provided by HP CHEMOSTATION software. The method used to create a calibration curve for measuring the blood desflurane concentration was modified according to a previous publication (8). …”

Hyperventilation increases the rate of the rise in arterial blood desflurane concentration during induction - a Gas Man® simulation

“…Lu et al described that hyperventilation accelerated the desflurane uptake from the alveolar to the arterial blood (1). It is a very intriguing study of a direct determination of the desflurane concentration in the arterial blood (Ades).…”

“…It is a very intriguing study of a direct determination of the desflurane concentration in the arterial blood (Ades). In comparison to the end-tidal volatile anesthetic concentration, the arterial concentration of a volatile anesthetic is more likely to reflect its concentration in the brain (1-3). …”

“…For the simulations, the necessary parameters and patient data were taken from the report of Lu et al (1): an anesthesia breathing circuit volume of 6 L; a fresh gas flow of 6 L/min; a functional residual capacity of 2.4 L; 61.8, 62.0, and 58.0 kg patient (hyperventilation, normal ventilation, and hypoventilation, mean values from each group); an alveolar minute ventilation of 3.33, 2.38, and 1.80 L/min, mean values from each group; cardiac output which was derived from the cardiac index of the report of Lu et al with Du Bois method (5.38, 5.56, and 5.36 L/min, mean values from each group). Other parameters were not manipulated.…”