Titration of Intraoperative PEEP in Patients Undergoing Robotic Assisted Laparoscopic Prostatectomy

Study Overview
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Brief Summary
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Optimal intraoperative positive end expiratory pressure (PEEP) improves the outcome. Optimal PEEP is not only very different among individuals, but each individual's optimal PEEP is affected by positioning, muscle paralysis, and several other factors. Several techniques have been used to determine the optimal PEEP. For example, electrical impedance tomography(EIT)can be performed at the bedside.However, the application of this technique requires special training, increases the workload of the care team, and the cost-efficiencyof this procedure remains to be determined.We hypothesized that optimal PEEP could be obtained by titration of intraoperative PEEP levels and FiO2with SpO2 guidance. Our secondary hypothesis was that maintenance of intraoperative optimal PEEP derived via this method improves intraoperative oxygenation and reduces the incidence of postoperative hypoxemia.We tested our hypothesis in patients undergoing robotic-assisted laparoscopic prostatectomy.

Detailed Description
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Lung-protective ventilation strategies are recommended for patients under mechanical ventilation with intermediate-risk and high-risk in order to minimize lung injury and respiratory complications of critically ill patients associated with mechanical ventilation , such as atelectasis and pneumonia. Low tidal volume (TV) had been proven protective . However, there is no consensus on what the optimal positive end expiatory pressure (PEEP) is for patients with healthy lungs undergoing general anesthesia, particularly for those who are undergoing abdominal surgery. A recent study showed that electrical impedance tomography (EIT) could be used to identify optimal PEEP, where both lungs collapse, hyper-insufflation is minimized, and the variation of optimal PEEP in patients with healthy lungs undergoing abdominal surgery is profound.Therefore, a fixed PEEP applied to all patients surely over-PEEP some and under-PEEP others. This study also demonstrates that maintaining the optimal PEEP intra-operatively not only improves intra-operative oxygenation but also reduces the incidence and severity of atelectasis post-operatively . Even though this study focuses on the improvement of physiology rather than the outcome, the benefit of intra-operative optimal PEEP is sustained for at least for one-hour post extubation. Therefore, optimized intra-operative PEEP could potentially have a positive impact onoutcomes. However, the cost-effectiveness of EIT used intraoperatively as routine practice still needs to be determined. Development of new methods which can be used intraoperatively and arecost-effective and user-friendly is an unmet demand. Recently, Ferrando et al conducted a study in which the authors used minimal FiO2 to maintain clinically acceptable arterial blood O2 saturation by titrating PEEP. Even though this study was not randomized and sample size was insufficient to demonstrate improved outcomes, it clearly demonstrated its feasibility and safety. We hypothesize that titration of intraoperative PEEP using minimal FiO2 while maintaining clinically acceptable O2 saturation allows clinicians to identify the optimal PEEP. We will test this hypothesis on patients undegoing RALP. We chose this population because these patients have increased number of postoperative complications . Additionally, physicians are prone to using suboptimal ventilation strategies such as inappropriate tidal volumes and intraoperative PEEP in this population; therefore these patients are more likely to achieve maximal benefit with optimized intra-operative PEEP.

Official Title
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Titration of Intraoperative Positive End-expiratory Pressure to Optimize Gas Exchange in Patients Undergoing Robotic Assisted Laparoscopic Prostatectomy

Conditions
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Positive End Expiratory Pressure

Intervention / Treatment
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* Other: Titration of Optimal Positive End-expiratory Pressure


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: adult patients aged 18 years or older scheduled for elective robotic-assisted laparoscopic prostatectomy(RALP) ASA physical status of I-III Exclusion Criteria: acute or chronic respiratory disorders pulmonary hypertension neuromuscular disease preoperative SpO2<95% on room air

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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Male

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: Other
Allocation: Randomized
Intervention Model: Factorial Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Optimal Positive End-expiratory Pressure obtained with Titration of Fraction of Inspiratory Oxygen<br>Obtained Optimal Positive End-expiratory Pressure obtained with Titration of Fraction of Inspiratory Oxygen and sustained the PEEP intraoperatively | Other: Titration of Optimal Positive End-expiratory Pressure<br>* Titration of Optimal Positive End-expiratory Pressure with two different methods<br>|
| Experimental: Optimal Positive End-expiratory Pressure obtained with electrical impedance tomography<br>Obtained Optimal Positive End-expiratory Pressure obtained with EIT and sustained the PEEP intraoperatively | Other: Titration of Optimal Positive End-expiratory Pressure<br>* Titration of Optimal Positive End-expiratory Pressure with two different methods<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The difference of optimal PEEP titrated by two methods | Titration result of the two groups | within 30 minutes after trachea intubation | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference of intraoperative PaO2/FiO2 between the two groups | intraoperative PaO2/FiO2 between the two groups | 30,60,120 minutes after finishing PEEP titration | 
| Difference of intraoperative driving pressure, dynamic compliance between the two groups | Difference of intraoperative driving pressure, dynamic compliance between the two groups | 30,60,120 minutes after finishing PEEP titration | 
| Difference of lung regional ventilation between the two groups | lung regional ventilation recorded by EIT | 5 minutes after trachea extubation | 
| Post operation hypoxemia in PACU. | Postoperative hypoxemia was defined as postoperative hypoxemia if SpO2<92%was detected in room air within 30 min after extubation in the PACU | within 30 minutes after trachea extubation |