title: The effects of prolonged inspiratory time during one-lung ventilation: a randomised controlled trial.
abstract: We evaluated the effects of a prolonged inspiratory time on gas exchange in subjects undergoing one-lung ventilation for thoracic surgery. One hundred patients were randomly assigned to Group I:E = 1:2 or Group I:E = 1:1. Arterial blood gas analysis and respiratory mechanics measurements were performed 10 min after anaesthesia induction, 30 and 60 min after initiation of one-lung ventilation, and 15 min after restoration of conventional two-lung ventilation. The mean (SD) ratio of the partial pressure of arterial oxygen to fraction of inspired oxygen after 60 min of one-lung ventilation was significantly lower in Group I:E = 1:2 compared with Group I:E = 1:1 (27.7 (13.2) kPa vs 35.2 (22.1) kPa, respectively, p = 0.043). Mean (SD) physiological dead space-to-tidal volume ratio after 60 min of one-lung ventilation was significantly higher in Group I:E = 1:2 compared with Group I:E = 1:1 (0.46 (0.04) vs 0.43 (0.04), respectively, p = 0.008). Median (IQR [range]) peak inspiratory pressure was higher in Group I:E = 1:2 compared with Group I:E = 1:1 after 60 min of one-lung ventilation (23 (22-25 [18-29]) cmH2O vs 20 (18-21 [16-27]) cmH2O, respectively, p < 0.001) and median (IQR [range]) mean airway pressure was lower in Group I:E = 1:2 compared with Group I:E = 1:1 (10 (8-11 [5-15]) cmH2O vs 11 (10-13 [5-16]) cmH2O, respectively, p < 0.001). We conclude that, compared with an I:E ratio of 1:2, an I:E ratio of 1:1 resulted in a modest improvement in oxygenation and decreased shunt fraction during one-lung ventilation.
authors.affiliation: Department of Anaesthesia and Pain Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
authors.forename: S M
authors.initials: SM
authors.lastname: Lee
authors.forename: W H
authors.initials: WH
authors.lastname: Kim
authors.forename: H J
authors.initials: HJ
authors.lastname: Ahn
authors.forename: J A
authors.initials: JA
authors.lastname: Kim
authors.forename: M K
authors.initials: MK
authors.lastname: Yang
authors.forename: C H
authors.initials: CH
authors.lastname: Lee
authors.forename: J H
authors.initials: JH
authors.lastname: Lee
authors.forename: Y R
authors.initials: YR
authors.lastname: Kim
authors.forename: J W
authors.initials: JW
authors.lastname: Choi
mesh_terms: D001784:Blood Gas Analysis / Q000379:methods; D002245:Carbon Dioxide / Q000097:blood; D005260:Female; D006801:Humans; D001239:Inhalation / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D061810:One-Lung Ventilation / Q000379:methods*; D010100:Oxygen / Q000097:blood; D011659:Pulmonary Gas Exchange; D015656:Respiratory Mechanics / Q000502:physiology; D019616:Thoracic Surgical Procedures; D013990:Tidal Volume; D013997:Time Factors
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen