Airway Peak Pressure-directed Laryngeal Mask Airway Intracuff Pressure Setting

Study Overview
=================
Brief Summary
-----------------
The investigators aimed to explore the effects of airway peak pressure (Ppeak) guidance on the least laryngeal mask airway (LMA) intracuff pressure setting during general anesthesia and the effects on postoperative complications in the throat. One hundred and twenty patients (American Society of Anesthesiologists grades I or II) scheduled for elective laparoscopic cholecystectomy under general anesthesia were enrolled in our study. The patients were divided into pressure-regulated group (group P) and control group (group C) randomly. Supreme LMA was inserted in after general anesthesia induction. Air was injected into the cuff to make the intracuff pressure (ICP) achieve 60 cmH2O. Volume-controlled ventilation was selected and Ppeak was recorded. In group P, all the gas in the LMA cuff was sucked out, and then air was injected in during expiration phase to make ICP achieve the level of Ppeak. If there's any leakage, increase 5 cmH2O every time till there's no air leakage from the mouth. After pneumoperitoneum, the cuff was inflated to make ICP achieve 60 cmH2O and Ppeak was recorded once more. Then all the gas in the LMA cuff was sucked out, and air was injected into the cuff during expiration phase to make ICP achieve the level of Ppeak as the above method till the end of operation. During pneumoperitoneum, the pressure of CO2 was set at 10 cmH2O. In group C, ICP was maintained at 60 cmH2O. Ppeak, ICP and the intracuff gas volume were recorded before and after pneumoperitoneum. ICP during inspiratory phase in the two groups was measured. Tidal volume during inspiration (VTI) and expiration (VTE) in the two groups were recorded, and the leakage rate was calculated as [(VTI-VTE)/ VTI×100%]. Throat complications of all the patients in 24 hours after surgeries were also recorded.

Official Title
-----------------
A Clinical Study of the Setting of Laryngeal Mask Airway Intracuff Pressure Based on Airway Peak Pressure

Conditions
-----------------
Laryngeal Mask Airway

Intervention / Treatment
-----------------
* Procedure: Airway peak pressure


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Patients with American Society of Anesthesiologists grades I or II scheduled for elective laparoscopic cholecystectomy under general anesthesia Exclusion Criteria: Patients with limited head and neck activity, limited mouth opening, high abdominal pressure, inflammation of the throat and respiratory diseases

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 65 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Intracuff pressure set by airway peak pressure<br> | Procedure: Airway peak pressure<br>* Air was injected into LMA cuff during expiration phase to make intracuff pressure achieve the level of airway peak pressure. If there's any leakage, increase 5 cmH2O every time till there's no air leakage from the mouth.<br>|
| Other: Intracuff pressure set at 60 mmHg<br> | Procedure: Airway peak pressure<br>* Air was injected into LMA cuff during expiration phase to make intracuff pressure achieve the level of airway peak pressure. If there's any leakage, increase 5 cmH2O every time till there's no air leakage from the mouth.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The intracuff gas volume before pneumoperitoneum | The changes of intracuff gas volume before pneumoperitoneum | Intraoperative | 
| The intracuff gas volume after pneumoperitoneum | The changes of intracuff gas volume after pneumoperitoneum | Intraoperative | 
| The intracuff pressure before pneumoperitoneum | The changes of intracuff pressure before pneumoperitoneum | Intraoperative | 
| The intracuff pressure after pneumoperitoneum | The changes of intracuff pressure after pneumoperitoneum | Intraoperative | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Throat complications | Throat pain, swallow discomfort and hematoma | From the end of operation till 24 hs postoperative |