The Effects of Chronic Obstructive Pulmonary Disease on the Washout Time of Sevofluorane Anesthesia

Having approval by the Duzce University non-invasive clinical ethics committee and the written consent, the study was conducted by researchers among 60 American Society of Anesthesiologists (ASA) physical status 1 or 2 patients scheduled for orthopedic, urologic and lower limp surgery which performed under general anesthesia .We investigated patients who have normal pulmonary function and who have chronic obstructive pulmonary disease .We divided into two groups by via questioning and evaluating pulmonary function tests of patients.

The patients were 18-60 years old, with body mass index between 22-29. The exclusion criteria were:

1. Cardiac failure
2. Hepatic failure
3. Renal failure
4. Neurologic diseases
5. Endocrine diseases Study design Neither group received premedication. After being taken to the operating room all patients were monitored continuously throughout the study by standard ASA monitors. In addition to standard ASA monitors, inspired oxygen concentration (FiO2 ), inspired and expired concentration of sevofluorane, MAC levels of the patients were monitored.

Anesthesia was induced by propofol (2mg . kg-1), fentanyl (1,5-2 mcg. kg-1), rocuronium(0,6mg. kg-1) intravenously. General anesthesia was maintained by remifentanyl infusion(0,25-1 mcg.kg-1.min-1) and sevofluorane (1 MAC level corrected for the patients age). Fresh gas flow was 6 L. min-1 (50%-50% oxygen/air mixture). Patients were mechanically ventilated (Vt: 6-8 ml. kg-1 , frequency: 9-12 breath.min-1), adjusted to provide an end-tidal CO2 concentration of 35-40 mmHg and SpO2> %95 during anesthetic and surgical procedure.The patients non-invasive arterial tension and heart rate was maintain within normal limits. All data were recorded on each patient's observation charts.

At the end of the surgery, the sevofluorane vaporizer was turned off and the time taken for the sevofluorane concentration to decrease from 1 MAC to 0.3 MAC (MAC awake) and 0.1 MAC were recorded. The ratio of the fraction of inspired of sevoflurane and of expired concentration (Fexp) of sevofluorane at 1 MAC and Fexp of sevofluorane at 0.1 MAC were recorded. Mechanical ventilations of the patients were maintained until extubation and standardized according to ideal body weight. All patients extubated immediately after the patients were given reaction to the endotracheal tube. Remifetanyl infusion was maintained until 0.1 MAC level was reached.