COMPARISON OF THE JACKSON-REES CIRCUIT, THE PEDIATRIC CIRCLE, AND THEMERA 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). Tw enty-three children (2-10 yr old) were studied during spontaneous brea thing under endotracheal anesthesia with 4 L/min nitrous oxide, 2 L/mi n oxygen, and 1% end-tidal concentration of sevoflurane. WOB, inspirat ory and expiratory airway resistance, dynamic compliance (C-DYN), pres sure time product (PTP), and arterial blood gasses were measured in th e three circuits. The inspiratory WOB was estimated directly by measur ing 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 circu it. WOB differed among the three circuits (MERA F system > pediatric c ircle > 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 hig her than those in both the Jackson-Rees circuit and the pediatric circ le. The MERA F system had significantly higher compliance than the Jac kson-Rees circuit and pediatric circle. It is concluded that the Jacks on-Rees circuit is most efficient, the pediatric circle is intermediat e, and the MERA F system is the least efficient from the viewpoint of WOB during spontaneous breathing for pediatric anesthesia.