Abstracts of Posters Presented at the International Anesthesia Research Society; 72nd Clinical and Scientific Congress; Orlando, FL; March 7-11, 1998: Pharmacology
INTRODUCTION: Propofol has desired characteristics as a sedative agent during regional anesthesia, namely, rapid recovery and easily controllable sedation level owing to its short elimination half life. On the other hand, the adverse effects, such as respiratory depression, coughing, euphoria, confusion and inadvertent movements, were reported . Coughing during surgery is unpleasant to patients and also to surgeon. In this study we tested if more incedences of coughing was accompanied during spinal anesthesia sadated with propofol than that with midazolam in patients undergoing orthoedic surgery.
METHODS: After approval of the study protocol by the local ethical committee, 29 adult non-premedicated patients, ASA physical status I or II, scheduled spinal anesthesia for orthopedic surgery were included in this study. Spinal anesthesia was carried out using hyperbaric 10-15mg tetracaine containing 0.125% phenylephrine at L2/3 or 3/4. Sensory block level was determined by pin prick technique 15min after injection. Propofol group patients (n=15) were infused propofol continuously using a computer controlled infusion device. Blood propofol concentration was set as to abolish the eye lid reflex. Midazolam group patients (n=14) were given midazolam, 0.5mg i.v., every 3 min until the lid reflex disappeared. The number of patients coughing during surgery was counted by visually, and compared between the groups using Mann Whitney U-test. P<0.05 was regared as statistically significant.
RESULTS: Mean calculated blood propofol concentration was 1.9 +/- 0.6 [micro sign]g/ml (mean +/- S.D.) in Propofol group. Mean midazolam dose given was 1.9 +/- 0.7 mg. Five patients in Propofol group (33%) and no one in Midazolam group (0%) coughed during surgery, p=0.013. The patients coughed anytime, and esecially in some patients they had a fit of coughing.
DISCUSSIONS: This study shows that propofol may contribute to the incidence of coughing during sedation undergoing spinal anesthesia, although the mechanism of which has not been clear yet. Propofol used for sedation during spinal anesthesia, especially in full stomach patients, can be a risk for vomiting and aspiration.
1. Anesth Intensivther Notfallmed 25: 186-92, 1990.