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Intraoperative changes in arterial oxygenation during volume‐controlled mechanical ventilation in modestly obese patients undergoing laparotomies with general anesthesia
Author(s) -
Yoshino J.,
Akata T.,
Takahashi S.
Publication year - 2003
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1034/j.1399-6576.2003.00147.x
Subject(s) - medicine , anesthesia , oxygenation , isoflurane , ventilation (architecture) , tracheal intubation , intubation , arterial blood , overweight , mechanical ventilation , artificial ventilation , tidal volume , oxygenation index , body mass index , respiratory system , respiratory disease , lung , mechanical engineering , engineering
Background: In obese patients, arterial oxygenation can be greatly impaired during general anesthesia. Both avoidance of denitrogenation and application of positive end‐expiratory pressure (PEEP) during mechanical ventilation may be effective in preventing such impairment of arterial oxygenation. Methods: We studied 28 obese/overweight and seven non‐obese (BMI < 25 kg · m −2 ) patients who underwent laparotomies with general anesthesia (i.e. isoflurane with or without nitrous oxide). During anesthesia, their lungs were mechanically ventilated at a rate of 10 breaths · min −1 with a constant flow, inspiratory‐to‐expiratory ratio 1 : 2, and tidal volume ∼10 ml · kg −1 . The obese/overweight patients were allocated to four different groups in terms of denitrogenation and application of PEEP (7 cm H 2 O) during the ventilation (n = 7 each). In the non‐obese patients, their denitogenated lungs were ventilated without application of PEEP. Arterial gas analyses were performed before induction of anesthesia, and 30, 90, 150 and 210 min after tracheal intubation. The ratio of PaO 2 to FiO 2 was calculated as an index of arterial oxygenation. Results: No significant changes in the PaO 2 /FiO 2 ratio were observed throughout the study in the non‐obese patients and in the obese/overweight patients whose non‐denitrogenated lungs were ventilated with PEEP. In the obese/overweight patients whose lungs were ventilated after denitrogenation or without application of PEEP, significant decreases in the PaO 2 /FiO 2 ratio were observed 30 and 90 min after tracheal intubation. Conclusions: In obese or overweight patients under general anesthesia, it may be advisable to avoid denitrogenation and apply PEEP during mechanical ventilation in order to minimize the impairment of arterial oxygenation.