Comparison of the Jackson-Rees Circuit, the Pediatric Circle, and the MERA F Breathing System for Pediatric Anesthesia

Abstract

The purpose of this study was to compare the Jackson-Rees circuit with the pediatric circle and MERA F breathing system (MERA F system) for pediatric anesthesia from the viewpoint of work of breathing (WOB). Twenty-three children (2-10 yr old) were studied during spontaneous breathing under endotracheal anesthesia with 4 L/min nitrous oxide, 2 L/min oxygen, and 1% end-tidal concentration of sevoflurane. WOB, inspiratory and expiratory airway resistance, dynamic compliance (C_DYN), pressure time product (PTP), and arterial blood gasses were measured in the three circuits. The inspiratory WOB was estimated directly by measuring the esophageal pressure-volume loop using the Campbell technique. In a laboratory study, we measured the compliances of the Jackson-Rees circuit, the pediatric circle, the MERA F system, and the adult circuit. WOB differed among the three circuits (MERA F system > pediatric circle > Jackson-Rees circuit). Inspiratory and expiratory resistances, and arterial carbon dioxide tension in the Jackson-Rees circuit were significantly lower than those of both the pediatric circle and MERA F system. The C_DYN and PTP in the MERA F system were significantly higher than those in both the Jackson-Rees circuit and the pediatric circle. The MERA F system had significantly higher compliance than the Jackson-Rees circuit and pediatric circle. It is concluded that the Jackson-Rees circuit is most efficient, the pediatric circle is intermediate, and the MERA F system is the least efficient from the viewpoint of WOB during spontaneous breathing for pediatric anesthesia. (Anesth Analg 1996;83:488-92)