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The impact of two different inspiratory to expiratory ratios (1:1 and 1:2) on respiratory mechanics and oxygenation during volume-controlled ventilation in robot-assisted laparoscopic radical prostatectomy: a randomized controlled trial

 Min-Soo Kim  ;  Na Young Kim  ;  Ki-Young Lee  ;  Young Deuk Choi  ;  Jung Hwa Hong  ;  Sun-Joon Bai 
 Canadian Journal of Anesthesia, Vol.62(9) : 979-987, 2015 
Journal Title
 Canadian Journal of Anesthesia 
Issue Date
BACKGROUND: Volume-controlled ventilation with a prolonged inspiratory to expiratory ratio (I:E ratio) has been used to optimize gas exchange and respiratory mechanics in various surgical settings. We hypothesized that, when compared with an I:E ratio of 1:2, a prolonged I:E ratio of 1:1 would improve respiratory mechanics without reducing cardiac output (CO) during pneumoperitoneum and steep Trendelenburg positioning, both of which can impair respiratory function in robot-assisted laparoscopic radical prostatectomy. Furthermore, we evaluated its effect on oxygenation during robot-assisted laparoscopic radical prostatectomy. METHODS: Eighty patients undergoing robot-assisted laparoscopic radical prostatectomy were randomly allocated to receive an I:E ratio of either 1:1 (group 1:1) or 1:2 (group 1:2). The primary endpoint, peak airway pressure (Ppeak), as well as hemodynamic data, including cardiac output (CO) and arterial oxygen tension (PaO2), were compared between groups at four time points: ten minutes after anesthesia induction (T1), 30 and 60 min after pneumoperitoneum with steep Trendelenburg positioning (T2 and T3), and ten minutes after supine positioning (T4). Overall comparisons were made between groups using linear mixed model analysis with post hoc testing of individual time points adjusted using a Bonferroni correction. RESULTS: Linear mixed model analysis showed a significant overall difference in Ppeak between the two groups (P < 0.001). Post hoc analysis showed a significantly lower mean (SD) Ppeak in group 1:1 than in group 1:2 at T2 [28.4 (4.0) cm H2O vs 32.8 (5.2) cm H2O, respectively; mean difference, 4.3 cm H2O; 95% confidence interval (CI), 2.3 to 6.4; P < 0.001] and T3 [27.8 (3.9) cm H2O vs 32.6 (5.0) cm H2O, respectively; mean difference, 4.7 cm H2O; 95% CI, 2.7 to 6.7; P < 0.001]. The CO assessed over these time points was comparable in both groups (P = 0.784). In addition, there were no significant differences in PaO2 between the two groups (P = 0.521). CONCLUSIONS: Compared with an I:E ratio of 1:2, a ratio of 1:1 lowered Ppeak without reducing CO during pneumoperitoneum and steep Trendelenburg positioning. Nevertheless, our results did not support its use solely for improving oxygenation. This trial was registered at http://clinicaltrials.gov/ (NCT01892449).
Appears in Collections:
1. Journal Papers (연구논문) > 1. College of Medicine (의과대학) > Dept. of Urology (비뇨의학교실)
1. Journal Papers (연구논문) > 1. College of Medicine (의과대학) > Yonsei Biomedical Research Center (연세의생명연구원)
1. Journal Papers (연구논문) > 1. College of Medicine (의과대학) > Dept. of Anesthesiology and Pain Medicine (마취통증의학교실)
Yonsei Authors
김나영(Kim, Na Young) ; 김민수(Kim, Min Soo) ; 배선준(Bai, Sun Joon) ; 이기영(Lee, Ki Young) ; 최영득(Choi, Young Deuk) ; 홍정화(Hong, Jung Hwa)
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