ABSTRACT
Justificativa e objetivos - O oxido nitroso (N2O) tem sido utilizado como gas intracavitario no homem e considerado menos irritante ao peritinio, quando comparado com o CO2. O N2O intracavitario tem mostrado menores alteracoes hemodidinamicas que o CO2 o que nos levou a utiliza-lo. Os objetivos deste estudo sao: a) Comparar os efeitos hemodinamicos e respiratorios entre o pneumoperitinio realizado com N2O e com o CO2, b) Comprovar a existencia de absorcao de N2O da cavidade abdominal e que esta pode influenciar no plano anestesico, e c) se ha diferentas na recuperacao pos-anestesica. Metodo - Vinte e oito pacientes adultos de ambos os sexos, estado fisico ASA I ou II, foram submetidos a colecistectomia por via laparoscopica, sob anestesia geral venosa divididos em dois grupos de acordo com o gas utilizado na cavidade peritoneal: Grupo C em que o gas foi o CO2, e o grupo N, que foi o N2O. A medicacao pre-anestesica (MPA) foi o diazepam por via oral. A anestesia foi induzida com propofol, atracurium, droperidol e alfentanil e mantida com propofol, e doses adicionais de alfentanil e de atracurium de acordo com as necessidades. Os dados hemodinamicos e ventilatorios foram registrados em onze omomentos (M1 a M11) que abrangeram os tempos compreendidos desde a estabiliacao da ventilacao, insuflacao e desinsuflacao abdominal, ate a recuperacao pos-anestesica nas primeiras tres horas. Foram registradas as variacoes da freqnencia ventilatoria (FV), a fracao expirada de oxido nitroso (PETN2O) e de gas carb(nico (PETCO2), o consumo de alfentanil, a eliminacao de N2O pelas vias aereas, as intercorrencias na sala de recuperacao pos-anestesica e a necessidade do emprego de antagonista de opiaceos. Resultados - Houve variacao da FV. Quanto ao volume minuto, houve diferentas significativas entre os dois grupos durante a manutencao do pneumoperitoneo e apos a desinsuflacao, com aumento significativo da FV nos pacientes do Grupo C em relacao aos do Grupo N. Embora sob hiperventilacao, no Grupo C a PETCO2 manteve-se mais elevada que no Grupo N. Foi detectado tratos de N2O na fracao expirada durante o pneumoperitoneo no Grupo N. A PAM apresentou valores maiores no Grupo C a partir da insuflacao abdominal, com diferentas significativas no tempo de quinze minutos apos a insuflacao inicial. No grupo N houve diferenca significativa da PAD cinco minutos apos a desinsuflacao abdominal com valores superiores. O Grupo C exigiu doses significativamente maiores de alfentanil que...
Subject(s)
Humans , Male , Female , Adult , Anesthesia, General , Cholecystectomy, Laparoscopic , Nitrous Oxide , Pneumoperitoneum, Artificial , Anesthesia Recovery Period , Carbon Dioxide , Hemodynamics , Respiration, ArtificialABSTRACT
Twenty-four patients of both sexes, physical status ASA I and II, were submitted to laparoscopic cholecystectomy. Patients were premedicated with 10 mg of diazepam and the anesthesia was induced with droperidol (0,03 mg.kg(-1)), alfentanil (40 mg.kg(-1)), propofol (2 mg.kg(-1) ) and atracurium (0,5 mg.kg(-1)). After tracheal intubation, pulmonary ventilation was maintained with a Takaoka 676 ventilator with a tidal volume of 7 ml.kg(-1), FiO2 of 0.33-0.35, intracheal pressure of 10-12 cmH2 O and respiratory rate adjusted to maintain ETCO2 36-38 mmHg and Sp)2 97-98 por cent. The patients were allocated into two groups. Group air: ventilated eith room air enriched with oxygen to a FiO2 of 0.35 and group N20: ventilated with 67 por cent N2O in O2. Maintenance of anesthesia was done with 10 mg.kg(-1).h(-1) of propofol in the first 20 min and with 5 mg.kg(-1).h(-1) afterwards until the end of the surgical procedure, plus intermittent doses of alfentanil. Changes in pulmonary ventilation rate and in the intratracheal pressures were record at nine moments. Carbon dioxide was administered until intrabdominal pressure reached 12-14 mm Hg; the initial and final volumes administered were recorded. The intracavitary concentration of N2O was evoluated by an Ohmeda 5250 Gas Multianalyser at the end of the procedure. Systolic and dystolic blood pressure and heart rate were evaluated every 5 min, at the same moments as the pulmonary ventilation parameters. There was no difference in the minute volumes at moment 1, but they were significantly higher at the subsequent moments (p major then 0,05), in the group which was ventilated with air. There were significant differences in intratracheal pressures before and the after the insuflation of CO2 and after the deflation within each group, but not between the groups. Nitrous oxide was detected in the abdominal cavity in remarkable concentrations. There were significant differences between the groups regarding systolic arterial pressure after insuflation and deflation of CO2, during maintenance and after extubation. The authors conclued that N2O diffuses to the abdominal cavity in significant concentrations and that it is able to minimize the respiratory changes associated with high intrabdominal pressure and with CO2 absorption. There were no differences in CO2 volumes required during the laparoscopic procedure