Anestesia cuantitativainfluencia del tamaño corporal en la eficacia de un nuevo dispositivo para la administración de anestésicos halogenados en circuitos cerrados

Abstract

When working with a vaporizer located outside the breathing circuit, the anesthetic vapour delivered into the system is dependent on fresh gas flow (FGF). This may be a major disadvantage for the complete closure of the anesthetic circuit. Also, when using low flow anesthesia, another disadvantage may be the difficulty in producing rapid changes in the anesthetic effect without FGF adjustments, due to the long time constant of the low flow circuits. Flow-independent delivery of volatile agents is an excellent alternative for overcoming these difficulties. Standard methods are placing the vaporizer inside the circuit (VIC) or injecting a calculated volume of the liquid agent directly into the circuit. The purpose of this study was to design and to evaluate the efficacy of a fresh gas flow independent-system that allows closing the anesthetic circuit from the begining of the procedure without restricting the volume of anesthetic vapour delivered to the system and minimizing drug consumption. In order to do so, a pump that propels the patient circle system gases in a continuous flow through a standard vaporizer (vaporizer outside the circuit, VOC) was introduced. The circulating flow, which is now a mixture of the anesthetic gas and the exhaled gases (after CO2 has been removed by the absorbent), is used to make the vaporizer work, thus the vaporizer is independent of the fresh gas flow. With this method, we can provide a quantitative anesthesia, adapting the gases delivery to the patient’s requirements. Oxygen is provided by a flowmeter calibrated to deliver the patient’s metabolic uptake...