The Effect of Prolonged Inspiratory Time on Gas Exchange During Robot-assisted Laparoscopic Surgery With Steep Trendelenburg Position : A Crossover Randomized Clinical Trial

Study Overview
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Brief Summary
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Gas exchange disturbance frequently occurs in steep Trendelenburg position during robot-assisted laparoscopic prostatectomy or cystectomy. Due to increased intrathoracic pressure and absorbed carbon dioxide (CO2) gas insufflated into abdominal cavity, hypercapnia as well as hypoxia may occur. Inverse ratio ventilation or prolonged inspiratory time during mechanical ventilation has been reported to be improve gas exchange in adult respiratory distress syndrome. The investigators attempt to test the hypothesis that prolonged inspiratory time may improve the gas exchange during robot-assisted laparoscopic urologic surgery.

Detailed Description
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Gas exchange disturbance frequently occurs in steep Trendelenburg position during robot-assisted laparoscopic prostatectomy or cystectomy. Due to increased intrathoracic pressure and absorbed CO2 gas insufflated into abdominal cavity, hypercapnia as well as hypoxia may occur. Inverse ratio ventilation or prolonged inspiratory time during mechanical ventilation has been reported to be improve gas exchange in adult respiratory distress syndrome. The investigators attempt to test the hypothesis that prolonged inspiratory time (I:E ratio = 1:1) may improve the gas exchange during robot-assisted laparoscopic urologic surgery.

Official Title
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The Effect of Prolonged Inspiratory Time on Gas Exchange During Robot-assisted Laparoscopic Surgery With Steep Trendelenburg Position : A Crossover Randomized Clinical Trial

Conditions
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Prostatic Neoplasm, Urinary Bladder Neoplasm

Intervention / Treatment
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* Device: Adjustment of Mechanical Ventilator Inspiratory to expiratory time ratio (1:2 to 1:1)
* Device: Adjustment of Mechanical Ventilator Inspiratory to expiratory time ratio (1:1 to 1:2)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: American Society of Anesthesiologists physical status class I-II and scheduled for an elective robot-assisted laparoscopic radical prostatectomy or robot-assisted laparoscopic radical cystectomy Patients who voluntarily decides to participate in the trial and has agreed in written informed consent Exclusion Criteria: Patients with the anatomical abnormalities of respiratory system(abnormal airway anatomy, severe scoliosis, post-pneumonectomy state), severe chronic respiratory diseases, chronic obstructive pulmonary disease (COPD), asthma, heart failure, obesity ( Body Mass Index [BMI] > 30kg/m2), severe hepatic failure or renal failure

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 1:2, 1:1 group<br>Inspiratory to expiratory time ratio (I:E ratio) of 1:2 during the first one hour of laparoscopy and then switched to I:E ratio of 1:1 during the rest time of laparoscopy. | Device: Adjustment of Mechanical Ventilator Inspiratory to expiratory time ratio (1:2 to 1:1)<br>* Adjustment of Mechanical Ventilator Inspiratory to expiratory time ratio (1:2 to 1:1)<br>|
| Active Comparator: 1:1, 1:2 group<br>Inspiratory to expiratory time ratio (I:E ratio) of 1:1 during the first one hour of laparoscopy and then switched to I:E ratio of 1:2 during the rest time of laparoscopy. | Device: Adjustment of Mechanical Ventilator Inspiratory to expiratory time ratio (1:1 to 1:2)<br>* Adjustment of Mechanical Ventilator Inspiratory to expiratory time ratio (1:1 to 1:2)<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| PaCO2 (mmHg) in the patient's arterial blood gas analysis | PaCO2 (arterial partial pressure of carbon dioxide) | 60 min after the initiation of pneumoperitoneum with steep Trendelenburg positioning | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| PaCO2 (mmHg) in the patient's arterial blood gas analysis | PaCO2 (arterial partial pressure of carbon dioxide) | 5 minutes after anesthesia induction | 
| PaO2 (mmHg) in the patient's arterial blood gas analysis | PaO2 (arterial partial pressure of oxygen) | 5 minutes after anesthesia induction | 
| PaO2 (mmHg) in the patient's arterial blood gas analysis | PaO2 (arterial partial pressure of oxygen) | 60 minutes after anesthesia induction | 
| PaCO2 (mmHg) in the patient's arterial blood gas analysis | PaCO2 (arterial partial pressure of carbon dioxide) | 120 minutes after anesthesia induction | 
| PaO2 (mmHg) in the patient's arterial blood gas analysis | PaO2 (arterial partial pressure of oxygen) | 120 min after the initiation of pneumoperitoneum with steep Trendelenburg positioning | 
| PaCO2 (mmHg) in the patient's arterial blood gas analysis | PaCO2 (arterial partial pressure of carbon dioxide) | 10 min after restoration of supine position | 
| PaO2 (mmHg) in the patient's arterial blood gas analysis | PaO2 (arterial partial pressure of oxygen) | 10 min after restoration of supine position | 
| Respiratory compliance (Static, Dynamic) | Static compliance = exhaled tidal volume / (plateau pressure - PEEP), Dynamic compliance = Exhaled tidal volume / (PIP - PEEP) | 5 minutes after anesthesia induction | 
| Respiratory compliance (Static, Dynamic) | Static compliance = exhaled tidal volume / (plateau pressure - PEEP), Dynamic compliance = Exhaled tidal volume / (PIP - PEEP) | 60 min after the initiation of pneumoperitoneum with steep Trendelenburg positioning | 
| Respiratory compliance (Static, Dynamic) | Static compliance = exhaled tidal volume / (plateau pressure - PEEP), Dynamic compliance = Exhaled tidal volume / (PIP - PEEP) | 120 min after the initiation of pneumoperitoneum with steep Trendelenburg positioning | 
| oxygen index | oxygen index calculated by PaO2/inspired oxygen fraction | 5 minutes after anesthesia induction | 
| oxygen index | oxygen index calculated by PaO2/inspired oxygen fraction | 60 min after the initiation of pneumoperitoneum with steep Trendelenburg positioning | 
| oxygen index | oxygen index calculated by PaO2/inspired oxygen fraction | 120 min after the initiation of pneumoperitoneum with steep Trendelenburg positioning | 
| Alveolar-arterial oxygen difference |  | 5 minutes after anesthesia induction | 
| Alveolar-arterial oxygen difference |  | 60 min after the initiation of pneumoperitoneum with steep Trendelenburg positioning | 
| Alveolar-arterial oxygen difference |  | 120 min after the initiation of pneumoperitoneum with steep Trendelenburg positioning |