Purpose: To evaluate the effectiveness of short-acting anesthetic drugs and techniques to achieve recovery room bypass criteria after minor surgery in a community hospital environment.Methods: After agreement by a multidisciplinary committee, a pilot project was undertaken to assess the usefulness of ultra-short acting anesthetic drugs and pre-emptive analgesia to facilitate rapid recovery from general anesthesia. A cohort of 100 ASA I-II patients aged 18-65 yr undergoing simple knee arthroscopy or minor peripheral orthopedic procedures was compared to a similar cohort treated in the three months prior to the study period. Outcomes of interest included patient morbidity, success in achieving post-anesthesia care unit (PACU) bypass criteria, impact upon nursing resources, duration of operating room (OR) and hospital stay, and pharmaceutical costs before and after implementation.

The resistance to gas flow is measured in the Jackson-Rees modification of the Ayre's T-piece, the "Bain" circuit, and the circle circuit using the conventionally employed rubber tubing, or either of two coaxial circle tubing systems. The Ayre's T-piece has the lowest resistance to gas flow, followed by the circle circuit with conventional rubber tubing, then the "Baln" circuit and the coaxial circle circuits. When the resistance to gas flow in the inspiratory limb is measured with a tracheal tube attached to each circuit the resistances increase in magnitude, but the differences among the circuits become less significant.

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A coaxial system to be used for gas delivery to patients in a closed or low fresh gas flow anaesthetic system is described. The resistance to gas flow, humidity of inspired gases, and static compliance of the circuit are provided and compared with the circle tubing customarily employed or the coaxial Mapleson D ("Bain") circuit. The resistance to gas flow is highest in the coaxial circle and "Bain" circuits; the resistance of the conventional circle is approximately 40 per cent less. Static compliance of this coaxial circle is 50 per cent greater than the conventional circle. During artificial ventilation humidity of inspired gases is maintainexl at levels recommended in the literature for all circuits, but during spontaneous breathing only the conventional robber circle maintains appropriate levels. Advantages of this coaxial circle over the conventional circle include light weight and small size. Advantages of this coaxial circle over the "Bain" circuit include lower fresh gas flows and improved humidity during spontaneous breathing. These advantages make this coaxial circle useful for routine use.