To compare the rate of uptake and elimination of volatile anesthetics, we administered 2%Halothane, 2% Enflurane and 2% Isoflurane respectively for one hour to 90 healthy adult patients through a semicolsed circuit with controlled ventilation to
maintain normocapnea for determining the rates of upkate, and the volatile anesthetics and nitrous oxide were discontinued to determine the rates of elimination for 30 minutes. The expired(FE-FA) and inspired(F1)vapor concentrations of volatile
anethetics were measured using an infrared analyser and FA/F1 ratios were used to determine rates of uptake, and FA/FAO(Where FAO is the last end-tidal concentration during uptake)ratios were used to determine rates of elimination.
And to evaluate the effects of gas flow pattern on the rate of uptake and elimination, the patients were divide into three group: Control group inhaled three volatile anesthetics respectively with 3( of oxygen per minute, study group 1 inhaled
three
volatile anesthetics respectively with 6( of oxygen per minute and study group 2 inhaled three volatile anesthetics respectively with 1( of oxygen and 2( of nitrous oxide.
@ES The results obtained were as follows:
@EN 1) To compare the rate of uptake(FA/F1) of the aneesthetics, the pulmonary uptake was most rapid with iisofluranc followed by enflurane and haiothane in accord with their respective solubilities in blood
2) With increased fresh gas flow, the rates of uptake of anesthetics more rapidly augmented, especially signiticantly in halothare and enflurane
3) With gas mixture of 70% N2O, the rate of uptake of anesthetics more rapidly augemented, especially significantly in isoflurane and enflurane
4) To compare the rate of elimination of anesthetics, isoflurane and enflurane eliminated more rapidly than halothane but there are no difference in that of isoflurane with enflurane in control group. But there are no difference significantly
between
that of halothane, enflurane and isoflurane in study group 1 and 2.
5) With increased gas flow rate, the rate of elimination decreased more rapidly in halothane, enflurane and isoflurane significantly.
6) By the elimination of anesthetics with N2O simultaneously for m the lung, the rate of elimination decreased more rapidly in halothane and isoflurane significantly.
In conclusion, we have shown that we can obtained more rapid induction and recovery of inhalation anesthetics with lower solubility of anesthetics. In addition, with increased fresh gas flow and use of gas mixture of nitrous oxide, induction and
recovery of anesthetics will be more rapidly.
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