The Appropriate Inflow Rates of Oxygen and Nitrous Oxide in Adult General Anesthesia / 대한마취과학회지

BACKGROUND: During adult general anesthesia, we used 3~5 L/min of fresh gas flow(FGF) but low FGF are employed, the amount of anesthetic consumption and air contamination can be reduced. The aim of this study was to determine the minimal appropriate inflow rate of oxygen and nitrous oxide during semiclosed circle technique. METHODS: We selected 40 patients, ASA group 1 or 2, scheduled for elective, nonabdominal surgery under general anesthesia with semiclosed circle system. Anesthesia was maintained with 50% oxygen, nitrous oxide and enflurane, controlled ventilation was used; rate of 10/min, tidal volume of 10 ml/kg. After induction and vital signs stabilized, FGF was changed to 4 L, 3 L, 2 L and 1L/min at interval of 30 minutes. We observed mean airway pressure and arterial blood gas tensions. RESULTS: The changes of mean airway pressure did not correlated with fresh gas inflow rate. In arterial blood gas analysis, PaO2 showed a decreasing tendency significantly according to decreasing fresh gas inflow rate(p<0.01) but there were no clinical hypoxemia in all patients. There were no significant changes in pH, PaCO2 and base excess. CONCLUSIONS: We consider that FGF of 1~2 L/min is appropriate during adult general anesthesia because of economic and ecological advantages. Also, we consider low flow technique with below 1L/min can be used safely and effectively under proper gas monitoring such as oxygen analyzer, capnometer.

Urinary Retention following Anorectal Surgery / 대한마취과학회지

Acute urinary retention is a common complication following anorectal surgery. However, the cause of this complication is poorly understood. We investigated the influence on postoperative urinary retention of age, sex, premedicants, intraoperative fluid volume administered, surgeon, operating time, type of operation, anesthetic technique in 278 patients undergoing elective surgery for benign anorectal disease by a review of the charts. The results were as follows. The overall urinary retention rate was 31.7%. Age, sex, premedicants (narcotics, anticholinergics), surgeon did not correlate with urinary retention. Increasing age was associated with a relatively high incidence of urinary retention, but the difference did not reach statistical significance (P=0.054). The variables of intraoperative fluid volume administered (>200 ml), anesthetic technique (spinal anesthesia vs. general or caudal anesthesia), type (hemorrhoidectomy, especially including multiple mucosal ligation or sphincterotomy) of the operation, and operating time (>30 min) correlated significantly with retention (P<0.05). Urinary retention was 2, 7 and 3 times more likely to occur in patients who had duration of operation more than 30 minutes, hemorrhoidectomy, and spinal anesthesia respectively. After all above variables were controlled for, duration and type of the procedure and anesthetic technique remained significantly correlated with retention (P<0.05). We concluded that operating time of more than 30 minutes, hemorrhoidectomy (especially using multiple mucosal ligations or sphincterotomy), and spinal anesthesia were significant precipitating factors, but could not determine whether age and intraoperative fluid volume administered were associated with urinary retention with this retrospective study.

The Effects of Verapamil and Nifedipine on Isolated Human Uterine Arteries / 대한마취과학회지

Isometric tension was recorded in uterine arterial ring preparation contracted by potassium (60 mM) and norepinephrine(1.8 X 10(-7) M). With pretreatment of various concentrations of nifedipine(2.9 x 10(-9) ~2.9 X10(-7) M) and verapamil(2.2 X 10(-7) -2.2 X 10(-5) M), the relaxation was dose-dependent and inhibitory effects of both agents were more marked on the potassium than norepinephrine-evoked contraction. After immersion of the arterial preparation in calcium-free solution, the potassium-evoked contraction was decreased to 21+/-4.1%(mean+/-SEM) of the response in normal Krebs solution and norepinephrine-evoked contraction to 26+/-3.8%. The responses to both agents were completely restored when the calcium concentration was increased to 4.0 mM. Pretreated nifedipine(2.9 x 10(-7) M) in calcium-free solution depressed the potassium-evoked contraction to 7.3+/-1.6% and norepinephrine-evoked contraction to 12+/-3.7%. In addition of calcium(0-4.0mM), the potassium-evoked contraction increased to 30+/-4.6% and that by norepinephrine to 45+/-5.4%. Pretreated verapamil(2.2 X 10(-5) M) in calcium-free solution depressed the potassium-evoked contraction to 14+/-3.6% and norepinephrine-evoked contraction to 18+/-3.3%. In addition of calcium(0-4.0mM), the potassium-evoked contraction increased to 41+/-4.2% and that by norepinephrine to 57+/-4.7%. It was concluded that nifedipine and verapamil relaxed KC1 contracted ring in the presence of external calcium and relaxed norepinephrine contracted ring in both the presence and absence of external calcium. These findings suggest that calcium antagonists interfere with the release of calcium from intracellular sites as well as with the slow inward current of calcium.