| BackgroundBecause low FGF bring less volatile agent from vaporizer and the diminution of anesthetic concentration within circuit by expired air , there is a marked difference between the concentration of anesthetic fresh gas and its concentration within the circuit . In order to satisfy the available depth of anesthesia , the vaporizer's setting must be increased during the course of LFA. However, for absent of a standardized scheme, it may be attached to subjective factor during the course of setting vaporizer or depend on the gas monitor fully. On one hand, which will impact on the efficient and consumption of anesthetic gas; on the other hand, it will prolong the phase of measurement and monitoring anesthetic concentration , which will decrease the practical value of LFA. At present for the sale of improving the scientific nature of low flow anesthesia technique , the mode of deliver fresh gas have been translated from a total flow to UBWF. Under such condition body weight can affect the setting of vaporizer, however the interaction between BW and GOV was very rare . Based on the reason the present study was designed to discuss interaction between BW and GOV of vaporizer during the course of LFA in adult and children under a special UBWF and deduce the formula, with the formula the low flow anesthe-sia can be performed safely and reasonably, even without gas monitor,MethodsThirty adult undergoing abdominal selective surgical procedures, the BW ranges from 50kg to 80kg and thirty children undergoing orthopedics selective surgical procedures, the BW ranges from 10kg to 40kg, were studied. Based on the different composition of fresh gas , each group was divided into two groups randomly, thus pure oxygen group and the oxygen mixed with nitrous oxide group. The premedica-tion and induction of anesthesia were used routinely. After trachea intubation, the mode of mechanical ventilation was designed to IPPV, tidal volume and breath frequency were set to 10 ml/kg and 12 ~ 18bpm respectively, I;E = 1:2. The UBWF was set to 10ml/kg in adult group and 20 ml/kg in children group respectively, the ratio between oxygen flow and nitrous oxide flow was designed 1:1. Observing the GOV when the depth of anesthesia was maintained from 1.3 to 1.4 MAC steadily during the course of sixty minutes LFA. The vaporizer can be closed about 15 to 20 minutes before the definite and of the surgical procedure. Not until about 5minutes before extubation, the fresh gas flow should be increased to 4 ~ 6L/min. Inorder to increase the depth of anesthesia in surgical procedure, fentany and vec can be used.ResultsBetween the oxygen group and nitrous oxide group comparison a-bout age, body weight, surgical time, anesthetic time was made, where significance was not found ( P > 0. 05 ). During the course ofLFA which maintain available depth of anesthesia for sixty minutes, inspired and expired concentration of isoflurane have a increased trend according to the prolongation of anesthesia time. Inspired and expired concentration of isoflurane in the oxygen group is higher than the nitrous oxide group for the effect of nitrous oxide. During the course of LFA PetCO2 ranged from 30mmHg to 40mmHg, SPO2 ranged from 97 to 100 percent, which indicates there is no hypoxia and carbon dioxide retention. Under such condition that BW and GOV submit to normality binomial distribution, With a FGF of 20ml/kg and the GOV deduced by the BW, in the group of children with oxygen, the line regress e-quation was ? =4.5402 -0.05502X, The correlation coefficient was - 0.9532; in the group of children with nitrous oxide, the line regress equation was ? =3. 5539 -0.0488X, the correlation coefficient was - 0. 9652. With a FGF of 10ral/kg ,in the group of adult with oxygen, the line regress equation was ? =5.0889 -0. 0259X , The correlation coefficient was - 0. 8775; in the group of adult with nitrous oxide, the line regress equation was ? =4.5413 -0. 02959X, and the correlation coefficient was - 0. 9218. Between adult group and children group comparison w... |
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