Comparison of the Jackson-Rees circuit, the pediatric circle, and the MERA F breathing system for pediatric anesthesia.

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 (CDYN), 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 CDYN 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.