[Postoperative epidural analgesia after upper abdominal surgery: the effects of low concentrations of bupivacaine combined with a low dose of opioid].

The efficacy and safety of postoperative analgesia with continuous epidural infusion of either morphine or fentanyl in combination with a low dose of bupivacaine were evaluated in 205 patients after upper abdominal surgery. Each patient was given bupivacaine alone (0.125% or 0.25%) or one of six combinations; 0.25%, 0.125%, or 0.0625% bupivacaine with morphine (M: 10 micrograms.ml-1) or fentanyl (F: 1 microgram.ml-1). After injection of 6 ml of each solution at the end of surgery, continuous epidural infusion was started at a rate of 4.2 ml.hr-1 for 48 hr. The degree of pain relief was assessed by the necessity of supplementary analgesics, the visual analogue pain scale and the Prince Henry pain scale. The most effective analgesic situation was obtained with the 0.25% M and the 0.25% F groups. The 0.125% M and 0.125% F groups showed adequate analgesia for elderly patients with few side effects. Regarding the plasma catecholamines measured 24 hr after the surgery, there was no significant change in fentanyl groups as well as in the group given 0.125% bupivacaine alone. Although the incidence of hypotension and pruritus was slightly higher in morphine groups, no patient developed respiratory depression. It is suggested, therefore, that a small dose of opioid should be added when continuous epidural infusion is required.

Nitrogen dioxide production in a nitric oxide inhalation system using the Servo Ventilator 900C.

During nitric oxide (NO) inhalation therapy, toxicity may be produced by the reactive metabolite nitrogen dioxide (NO2). The purpose of the present study was to determine the NO2 concentration in a NO inhalation system used for respiratory failure in children at relatively low concentrations of NO (< 20 ppm). The production of NO2 in the NO inhalation system using the Servo Ventilator 900C connected to the test lung under each of 30 combinations of NO concentrations (0, 4, 8, 12, 16, and 19 ppm) and inspired oxygen (O2) concentrations (21, 40, 60, 80, and 100%). Pressure controlled ventilation was used with a respiratory rate of 20 breaths/min. NO and NO2 measurements were obtained on the inspiratory side of the Y-piece connected to the test lung. At a given NO level, increases in the concentration of inspired O2 resulted in increases in the concentration of NO2 produced, as did increases in the amount of NO at a given concentration of O2. The mean NO concentration at the inspiratory site of the Y-piece did not exceed 0.05 ppm (the limit of NO2 as an outdoor air pollutant in the United States) when the NO concentration did not exceed 8 ppm, regardless of the O2 concentration. NO inhalation therapy for children with severe respiratory failure using the Servo Ventilator 900C can be performed safely when the concentration of NO does not exceed 8 ppm.

Evaluation of Mapleson systems for administration of inhaled nitric oxide.

To assess the safety of nitric oxide (NO) inhalation during manual-controlled ventilation using Mapleson A, D, and F systems, we examined nitrogen dioxide (NO2) production using a chemiluminescence analyzer. The NO concentration was changed from 0 to 19 parts per million (ppm), and at each level of NO the oxygen (O2) concentration was changed from 21% to 100%. The NO2 concentration was observed to increase when either the O2 or NO concentration was increased. The maximum NO2 concentrations (mean ± standard deviation) of the Mapleson A, D, and F systems were 0.20±0.03, 0.15±0.03, and 0.17±0.02 ppm, respectively, when the concentrations of NO and O2 were 19 ppm and 100%, respectively. The NO2 concentrations of the Mapleson A system were significantly higher than those of either the Mapleson D or F system at 4, 8, and 12 ppm NO and 100% O2, and than that of the Mapleson D system at 19 ppm NO and 100% O2. From the viewpoint of NO2 production, we suggest that the Mapleson D and F systems are safer than the Mapleson A system when manual-controlled ventilation is required.

[Optimum dose of intravenous butorphanol as a supplemental drug during regional anesthesia].

The optimum doses according to age of butorphanol tartrate as a supplemental drug during epidural and spinal anesthesia were investigated in 60 patients without complications. We classified patients into 4 groups by age as A, B, C and D-group. A-group consisting of patients between 20 to 40 years received 1.5mg of butorphanol. B-group 41-60, C-group 61-75 and D-group over 76 years received 1.0mg, 0.5mg and 0.25mg respectively. After operation was started without pain, and during the stable period, we determined by age, doses of butorphanol injected intravenously in one minute. HRs, mean BPs, respiratory rates (RRs) and so on were obtained at the preinjection point and 5 minutes after injection. In addition, in 15 patients, arterial blood gas analysis was performed at the same times. Butorphanol injections decreased HRs, mean BPs and RRs significantly. But there was no one whose PaCO2 increased more than 50 mmHg and no difference was found in degree of side effects between the groups. In conclusion, this study suggests that the decision to administer doses depending on the age is useful to decrease frequency of the grave side effects, especially respiratory depression which the elderly people frequently fall into.