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Distribution of diaphragm blood flow during sevoflurane anaesthesia in dogs
1Department of Anesthesiology, School of Medicine, Chiba University, Japan.
Purpose:
The purpose of this study was to determine the effect of increasing the concentrations of sevoflurane anaesthesia on the distribution of diaphragm blood flow (Qdi) in ten dogs during mechanical ventilation.
Methods:
Animals were divided into two groups, sevoflurane (n = 6) and time control (n = 4) groups. Blood flow to the crural and the costal diaphragm (Qcru, Qcost) was determined by the hydrogen clearance technique at 0, 0.5, 1.0 and 1.5 minimum alveolar concentration (MAC) of sevoflurane after a 30 min period of steady-state conditions. Cardiac output (CO) and the mean arterial blood pressure (MBP) were also measured.
Results:
Sevoflurane anaesthesia caused a reduction in CO (L.min-1) from a control value of 1.51 +/- 0.21 to 1.38 +/- 0.1 (0.5 MAC), 1.09 +/- 0.15 (1.0 MAC) and 0.98 +/- 0.12 (1.5 MAC) (Mean +/- SD). Mean blood pressure, Qcru and Qcost also decreased with increasing depth of anaesthesia. In addition, the decrease of Qcru was greater than that of Qcost at all levels of MBP and CO. No change occurred in these variables in the time control group.
Conclusion:
Sevoflurane anaesthesia changes the distribution of Qdi with a greater reduction occurring in Qcru than in Qcost.