[Positive end-expiratory pressure facilitates washout of nitrous oxide in patients with obstructive pulmonary disease].
This study was designed to investigate the relationship between nitrous oxide elimination and each value of pulmonary function tests: percent vital capacity, air way resistance and percent of forced expiratory pressure (FEV1.0%) in patients undergoing general anesthesia. Furthermore, the effect of positive end-expiratory pressure (PEEP) on nitrous oxide elimination was studied. Thirty nine patients, anesthetized by oxygen, nitrous oxide and sevoflurane, were allocated randomly to one of two groups; one, with PEEP 10 cmH2O during nitrous oxide elimination and the other, without. After discontinuation of nitrous oxide, the concentration of nitrous oxide was measured at 15 sec intervals under controlled ventilation with 100% oxygen-sevoflurane. There was a significant correlation between nitrous oxide washout time and FEV1.0% (P < 0.05). Patients were further divided into two subgroups: FEV1.0% of over 70% (normal FEV) and that of less than 70% (low FEV). In the normal FEV group, the washout time was unaffected by PEEP. In the low FEV group, the washout times, with and without PEEP, were 7.07 +/- 0.93 min and 9.13 +/- 2.32 min, respectively. The difference was significant (P < 0.05). These results suggest that patients with chronic obstructive lung disease are at risk of delay in nitrous oxide elimination. This delay was found to be preventable with PEEP.
Yamazaki
Y
Y
Department of Anesthesiology, Kushiro City General Hospital.
Mimura
M
M
Sonoda
H
H
Seki
S
S
Namiki
A
A
D000368:Aged; D000768:Anesthesia, General; D018685:Anesthetics, Inhalation / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D008168:Lung / Q000378:metabolism*; D008173:Lung Diseases, Obstructive / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D008448:Maximal Expiratory Flow Rate; D008875:Middle Aged; D009609:Nitrous Oxide / Q000493:pharmacokinetics*; D011175:Positive-Pressure Respiration
D018685:Anesthetics, Inhalation; D009609:Nitrous Oxide