Driving Pressure Guided Ventilation Versus Conventional Lung Protective Strategy in Morbid Obese Patients Undergoing Laparoscopic Bariatric Surgery

Study Overview
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Brief Summary
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This study will be conducted to evaluate the effect of driving pressure guided ventilation compared with conventional protective lung ventilation during laparoscopic bariatric surgeries in morbid obese patients. the primary outcome: Intraoperative oxygenation measured by the arterial partial pressure of oxygen (PaO2). the secondary outcome: incidence of early postoperative pulmonary complications e.g., postoperative hypoxia, the need for supplementary oxygen, atelectasis, barotrauma, and respiratory failure.

Detailed Description
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Protective mechanical ventilation during anesthesia aims at minimizing lung injury and has been associated to a decrease in postoperative pulmonary complications (PPCs). Conventional protective ventilation strategy is consisted of the use of a low tidal volume (VT) and fixed moderate positive end expiratory pressure (peep). However, low-VT may result in the reduction of the functional volume of the lung manifested as lung collapse. Another potential consequence of lung collapse is the impairment in ventilatory efficiency. Bariatric surgery is proven to achieve significant and sustained weight loss in the morbidly obese. Major weight loss can lead to partial/complete resolution of a range of conditions including, diabetes mellitus, ischemic heart disease, and hypertension. Obese patients undergoing general anesthesia and mechanical ventilation during abdominal and bariatric surgeries commonly have a higher incidence of postoperative pulmonary complications (PPCs), due to factors such as decreasing oxygen reserve, declining functional residual capacity, and reducing lung compliance. And also pneumoperitoneum aggravates pulmonary atelectasis caused by mechanical ventilation, especially in obese patients. Driving pressure (DP) which is the difference between the airway pressure at the end of inspiration (plateau pressure, (Ppl) and PEEP was first introduced by Amato et al in 2015 in their meta-analy¬sis study for ARDS patients. The authors suggested that driving pressure is the stronger predictor of mortality as compared with low VT and Ppl. Several retrospec¬tive and prospective studies confirmed the importance of driving pressure in ARDS pa¬tients and during general anesthesia without differentiation between obese and nonobese patients .only one retrospective study showed that driving pressure was not associated with mortality in obese-ARDS patients. we hypothesize that these results may be different in obese patients having healthy lungs.

Official Title
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Driving Pressure Guided Ventilation Versus Conventional Lung Protective Strategy in Morbid Obese Patients Undergoing Laparoscopic Bariatric Surgery; a Prospective Randomized Controlled Study

Conditions
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Driving Pressure

Intervention / Treatment
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* Procedure: driving pressure guided ventilation
* Procedure: Conventional protective lung strategy


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: sixty patients have a BMI 40-50 kg/m2, ASA physical status III, aged between 18 and 60 years, scheduled to undergo laparoscopic bariatric surgeries. Exclusion Criteria: patient refusal to participate in the study. Patients had a recent history of severe respiratory disease and previous major pulmonary surgeries. patients who are contraindicated with application of PEEP (high intracranial pressure, bronchopleural fistula, hypovolemic shock, right ventricular failure).

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Driving pressure guided ventilation<br>Patients will be mechanically ventilated with driving pressure guided ventilation with VT 6-8 ml /kg of predicted body weight, and after recruitment we will return to the baseline PEEP 5 cmH2O that will be increased by 2 cmH2O until reaching the lowest possible driving pressure for every patient. Each PEEP level will be applied for 10 respiratory cycles and DP will be calculated at the last cycle. | Procedure: driving pressure guided ventilation<br>* driving pressure guided ventilation<br>|
| Active Comparator: Conventional protective lung strategy<br>Patients will be mechanically ventilated with conventional protective lung strategy with VT 6-8 ml /kg of predicted body weight, after recruitment, we will return to the baseline PEEP 5 cmH2O and will be maintained until the end of surgery. | Procedure: Conventional protective lung strategy<br>* Conventional protective lung strategy<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Intraoperative oxygenation measured by the arterial partial pressure of oxygen (PaO2). | Arterial blood gases -for measurement of pao2- will be sampled after induction of anesthesia (baseline) ,10 minutes after recruitment, before end of surgery, and 30 minutes after extubation. | the time of surgery | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| the need for rescue recruitment | the need for rescue recruitment | the time of surgery | 
| incidence of early postoperative pulmonary complications e.g., postoperative hypoxia, the need for supplementary oxygen, atelectasis, barotrauma, and respiratory failure. | ncidence of early postoperative pulmonary complications e.g., postoperative hypoxia, the need for supplementary oxygen, atelectasis, barotrauma, and respiratory failure. | First 24 hours postoperative |