Intraoperative Ventilatory Strategies for Prevention of Pulmonary Atelectasis in Obese Patients Undergoing Laparoscopic Bariatric Surgery

Department of Anesthesiology, King Faisal Specialist Hospital & Research Centre, Jeddah, Saudi Arabia.
Anesthesia and analgesia (Impact Factor: 3.47). 11/2009; 109(5):1511-6. DOI: 10.1213/ANE.0b013e3181ba7945
Source: PubMed


Atelectasis occurs regularly after induction of general anesthesia, persists postoperatively, and may contribute to significant postoperative morbidity and additional health care costs. Laparoscopic surgery has been reported to be associated with an increased incidence of postoperative atelectasis. It has been shown that during general anesthesia, obese patients have a greater risk of atelectasis than nonobese patients. Preventing atelectasis is important for all patients but is especially important when caring for obese patients.
We randomly allocated 66 adult obese patients with a body mass index between 30 and 50 kg/m(2) scheduled to undergo laparoscopic bariatric surgery into 3 groups. According to the recruitment maneuver used, the zero end-expiratory pressure (ZEEP) group (n = 22) received the vital capacity maneuver (VCM) maintained for 7-8 s applied immediately after intubation plus ZEEP; the positive end-expiratory pressure (PEEP) 5 group (n = 22) received the VCM maintained for 7-8 s applied immediately after intubation plus 5 cm H(2)O of PEEP; and the PEEP 10 group (n = 22) received the VCM maintained for 7-8 s applied immediately after intubation plus 10 cm H(2)O of PEEP. All other variables (e.g., anesthetic and surgical techniques) were the same for all patients. Heart rate, noninvasive mean arterial blood pressure, arterial oxygen saturation, and alveolar-arterial Pao(2) gradient (A-a Pao(2)) were measured intraoperatively and postoperatively in the postanesthesia care unit (PACU). Length of stay in the PACU and the use of a nonrebreathing O(2) mask (100% Fio(2)) or reintubation were also recorded. A computed tomographic scan of the chest was performed preoperatively and postoperatively after discharge from the PACU to evaluate lung atelectasis.
Patients in the PEEP 10 group had better oxygenation both intraoperatively and postoperatively in the PACU, lower atelectasis score on chest computed tomographic scan, and less postoperative pulmonary complications than the ZEEP and PEEP 5 groups. There was no evidence of barotrauma in any patient in the 3 study groups.
Intraoperative alveolar recruitment with a VCM followed by PEEP 10 cm H(2)O is effective at preventing lung atelectasis and is associated with better oxygenation, shorter PACU stay, and fewer pulmonary complications in the postoperative period in obese patients undergoing laparoscopic bariatric surgery.

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Available from: Ibrahim Ali Zabani, Jun 16, 2015
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    • "Prolonging I:E ratio increases Pmean and Cdyn while decreases Ppeak. This would recruit atelectatic alveoli and hence improves arterial oxygenation.[712] Owing to these theoretical advantages, and our clinical experience, we suggested that, ERV will improve arterial oxygenation in patients undergoing laparoscopic bariatric surgery compared to conventional 1:2 ratio ventilation. "
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    ABSTRACT: Hypoxaemia and high peak airway pressure (Ppeak) are common anesthetic problems during laparoscopic bariatric surgery. Several publications have reported the successful improvement in arterial oxygenation using positive end expiratory pressure and alveolar recruitment maneuver, however, high peak airway pressure during laparoscopic bariatric surgery may limit the use of both techniques. This study was designed to determine whether equal I:E (inspiratory-to-expiratory) ratio ventilation (1:1) improves arterial oxygenation with parallel decrease in the Ppeak values. Thirty patients with a body mass index ≥40 kg/m(2) scheduled for laparoscopic bariatric surgery were randomized, after creation of pneumoperitoneum, to receive I:E ratio either 1:1 (group 1, 15 patients) or 1:2 (group 2, 15 patients). After a stabilization period of 30 min, patients were crossed over to the other studied I:E ratio. Ppeak, mean airway pressure (Pmean), dynamic compliance (Cdyn), arterial blood gases and hemodynamic data were collected at the end of each stabilization period. VENTILATION WITH I: E ratio of 1:1 significantly increased partial pressure of O2 in the arterial blood (PaO2), Pmean and Cdyn with concomitant significant decrease in Ppeak compared to ventilation with I: E ratio of 1:2. There were no statistical differences between the two groups regarding the mean arterial pressure, heart rate, respiratory rate, end tidal CO2 or partial pressure of CO2 in the arterial blood. Equal ratio ventilation (1:1) is an effective technique in increase PaO2 during laparoscopic bariatric surgery. It increases Pmean and Cdyn while decreasing Ppeak without adverse respiratory or hemodynamic effects.
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    • "The increased intrapleural pressure caused by PEEP might also increase the risk of barotrauma and cause changes to cardiovascular dynamics. Two trials reported postoperative barotrauma in both PEEP and ZEEP [14, 15]. The event rate was zero in both groups in both trials. "
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    • "This may be explained by the role of noninvasive ventilation (NIV) in preventing alveolar derecruitment decreasing the possibility of atelectasis, pneumonia and eventually respiratory failure. This was in contrast with Talep et al. [29] who recorded no postoperative complications with PEEP 10 recruitment maneuver; however, they studied patient population with BMI lower than our patient's populations (30–50 kg/m 2 ). Moreover, these reported complications may be directly attributed to the prolonged ICU stay in these two groups. "
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