The Clinical Study of Two Modified Methods for Pediatric Anesthesia

Kim, Heung Dae

Abstract

During the last decade, nonrebreathing systems have been used most extensively for neonate and small children, but these systems can lead to alveolar hyperventilation when it was used manually because these systems have not volumometer to measure the tidal volume of patients. Therefore, the author devised two modified methods that is able to estimate the tidal volume of patients using the volumometer in the adult circle system for pediatric anesthesia. One method is modified Jackson Rees system. The Y-piece of the adult circle system was removed and the inspiratory gas tube of the Jackson Rees system was connected to the inspiratory corrugated tube of the adult circle system and the expiratory reservoir tube of the Jackson Rees system was connected to the expiratory corrugated tube of the adult circle system, then was ventilated with reservoir bag of the adult circle system. The other method is modified Y-piece system. The deadspace of Y-piece of the adult circle system was reduced by set up of short cannula in the inspiratory side of the Y-piece, then was ventilated with reservoir bag of the adult circle system. Using above two modified methods, study was undertaken in 25 cases to determine whether adequate alveolar ventilation could be maintained for pediatric anesthesia. The ventilation was carried out as the discretionary manual ventilation, and as the estimated tidal volume of patients using the volumometer in the adult circle system, respectively. In the latter method, tidai volume was 8 ml/kg and respiratory rate was 35 breaths/min under 5 kg of body weight, 30 breaths/min weighing 5 kg-10 kg and 20 breaths/min over 10 kg. Total gas flow of these systems was 2.5 times minute volume of patients. Arterial blood gas tension was measured 30 minutes after the induction of anesthesia. The following results were obtained. 1) In the method of the original Jackson Rees system, when it was ventilated manually and discretionary in 5 cases, PaCO2 level was 21.0+/-1.65mmHg. 2) In the method of the modified Jackson Rees system, when it was ventililated manually and discretionary in 5 cases, PaCO2 level was 25.1+/-0.52mmHg, and was ventilated as estimated tidal volume of patients in 5 cases, PaCO2, level was 37.6+/-0.45 mmHg. 3) In the modified Y-piece system, when it was ventilated manually and discretionary in 5 cases, PaCO2, level was 21.3+/-1.37 mm Hg, and was ventilated as estimated tidal volume in 5 cases, PaCO2 level was 36.2+/-1.01mmHg. Therefore, it could be assumed that these two modified methods are a good device to maintain an appropriate alveolar ventilation for pediatric anesthesia.