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A Journal on Anesthesiology, Resuscitation, Analgesia and Intensive Care

Official Journal of the Italian Society of Anesthesiology, Analgesia, Resuscitation and Intensive Care
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Minerva Anestesiologica 2002 June;68(6):523-7

language: English

Wash-in and wash-out curves of sevoflurane and isoflurane in morbidly obese patients

Torri G., Casati A., Comotti L., Bignami E., Santorso- la R., Scarioni M.

From the Department of Anesthesiology IRCCS H. San Raffaele Vita-Salute University of Milan - Milan


Background. The aim of ­this pros­pec­tive, ran­dom­ized ­study is to com­pare sevof­lu­rane and iso­flu­rane phar­ma­cok­i­net­ics in mor­bid­ly ­obese ­patients.
Methods. With Ethical Committee approv­al and writ­ten ­informed con­sent, 14 ­obese ­patients (BMI >35 kg/m2), ASA phys­i­cal stat­us II, under­go­ing lapar­os­cop­ic, sil­i­cone-adjust­able gas­tric band­ing ­were ran­dom­ly allo­cat­ed to ­receive ­either sevof­lu­rane (n=7) or iso­flu­rane (n=7) as ­main anes­thet­ic ­agents. General anes­the­sia was ­induced ­with 1 µg·kg-1 fen­ta­nyl, 6 mg·kg-1 sodi­um thi­o­pen­tal, and 1 mg·kg-1 suc­ci­nyl­cho­line fol­lowed by 0.4 mg kg-1·h-1 atra­cu­ri­um bro­mide (dos­es ­were ­referred to ­ideal ­body ­weight). Intermittent pos­i­tive pres­sure ven­ti­la­tion (IPPV) was ­applied ­using a Servo-900C ven­ti­la­tor ­with a non­re­breath­ing cir­cuit and a 15 l·min-1 ­fresh gas ­flow (­tidal vol­ume: of 10 ml·kg-1; res­pir­a­to­ry ­rate: 12 ­breaths/min; inspir­a­to­ry to expir­a­to­ry ­time ­ratio of 1:2) ­using an oxy­gen/air mix­ture (FiO2=50%), ­while sup­ple­men­tal bolus­es of thi­o­pen­tal or fen­ta­nyl ­were giv­en as indi­cat­ed in ­order to main­tain ­blood pres­sure and ­heart ­rate val­ues with­in ±20% ­from base­line. After ade­quate place­ment of tra­cheal ­tube and sta­bil­iza­tion of the ven­ti­la­tion param­e­ters, 2% sevof­lu­rane or 1.2% iso­flu­rane was giv­en for 30 min via a non­re­breath­ing cir­cuit. End-­tidal sam­ples ­were col­lect­ed at 1, 5, 10, 15, 20, 25 and 30 min, and meas­ured ­using a cal­i­brat­ed ­infrared gas ana­lyz­er. General anes­the­sia was ­then main­tained ­with the ­same inha­la­tion­al ­agents, ­while sup­ple­men­tal fen­ta­nyl was giv­en as indi­cat­ed. After the ­last ­skin ­suture the inha­la­tion­al ­agents ­were sus­pend­ed, and the end ­tidal sam­ples ­were col­lect­ed at 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5 min. Then the ­lungs ­were man­u­al­ly ven­ti­lat­ed ­until extu­ba­tion.
Results. No dif­fer­enc­es in age, gen­der and ­body ­mass ­index ­were report­ed ­between the two ­groups. Surgical pro­ce­dure ­required 91±13 in the sevoflurane ­group and 83±32 min in the isoflurane ­group. The FA/FI ­ratio was high­er in the sevoflurane ­group ­from the 5th to the 30th min. Also the wash­out ­curve was fast­er in the sevof­lu­rane ­group dur­ing the obser­va­tion peri­od; how­ev­er, the ­observed dif­fer­enc­es ­were sta­tis­ti­cal­ly sig­nif­i­cant ­only 30 and 60 sec ­after dis­con­tin­u­a­tion of the inha­la­tion­al ­agents.
Conclusions. The ­results of ­this pros­pec­tive, ran­dom­ized ­study con­firmed ­that sevof­lu­rane pro­vides ­more rap­id ­wash-in and ­wash-out ­curves ­than iso­flu­rane ­also in the mor­bid ­obese ­patient.

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