Comparison Of Two Methods Of Proseal Laryngeal Mask Airway Size Selection In Laparoscopic Cholecystectomy

Objective:The purpose of this study was to determine the optimal method of proseal laryngeal mask airway（PLMA）size selection in laparoscopic cholecystectomy.By comparing the oropharyngeal leak pressure（OLP）and related complications to verify whether the PLMA can be safely and effectively used in laparoscopic cholecystectomy.Methods:We conducted a randomised study involving sixty patients who undergoing laparoscopic cholecystectomy in general anesthesia.Sixty patients,ASA physical status I-III,aged 18-80 years,BMI<30kg/m²,and had no severe heart and lung disease were divided into groups A（n=30）and B（n=30）according to the random number table.In the first group（group A）,the selection of the size of PLMA was based on the body weight（30-50kg:size 3;50-70kg:size 4;over70kg:size 5）.In the other group（group B）,the size of PLMA was selected by patient’s gender（Female:size 4;Male:size 5）.After the patient entered the operating room,peripheral venous access was routinely opened and the electrocardiogram（ECG）,pulse oximetry（Sp O₂）,noninvasive arterial pressure（NIBP）,and end-expiratory carbon dioxide(P_ETCO₂)were monitored.Both PLMA devices were prepared for insertion with the cuff completely deflated and the dorsal surface lubricated with a water-soluble jelly.The patients were anesthetized with midazolam 0.04 mg/kg,sufentanil 0.4μg/kg,etomidate 0.2-0.3 mg/kg,and cisatracurium 0.2 mg/kg.When the patient’s jaw was relaxed and the eyelash reflex disappeared,the selected PLMA was inserted using the traditional index finger push method,and the cuff was inflated with air to the optimum intracuff pressure of60cm H₂O.Judge the ventilation and alignment of the PLMA after placement.An effective airway was defined by the presence of normal thoracoabdominal movement and a squarewave capnograph trace.A well lubricated 14 French gauge gastric tube was placed through the drain tube of the PLMA,and the ease of insertion of the gastric tube was recorded.Placement of the gastric tube in the stomach was confirmed by auscultation of the upper abdomen or aspiration of gastric contents.If the PLMA had poor ventilation or the gastric tube failed to be placed,the PLMA would be placed again.A maximum of three attempts were permitted.If the device was considered a failure,it would be replaced with intubation.When the PLMA was inserted for 5minutes,we would tese the oropharyngeal Leak Pressure（OLP）.we also passed a flexible fiberoptic bronchoscope（FOB）through the airway tube of the PLMA and recorded fibreoptic bronchoscopy score.A close circle system was connected and the ventilation was using volume controlled positive pressure with tidal volume of 8 ml/kg,respiratory rate of 12 breaths/min,and inspiratory-to-expiratory time（I:E）ratio of 1:2to maintain end-tidal carbon dioxide level of 35-40mm Hg.The pneumoperitoneal pressure was maintained at 12±2 cm H₂O during the operation,and the patients were putting on reverse trendelenburg position.During the operation,propofol were continuously pumped at 4-6μg/kg·min and remifentanil were pumped at 0.05-0.2μg/kg·min,and cisatracurium was intermittently added.After the completion of surgery,neostigmine 0.04 mg/kg and atropine 0.02 mg/kg were administered to reverse the residual neuromuscular block.The PLMA was removed when the patient was awake,breathing spontaneously,and responding to verbal commands.Postoperative pain was cured with flurbiprofen 1 mg/kg.The size of PLMA,number of attempts,the ease of insertion of the PLMA and drain tube,the first attempt success rate of the PLMA,anatomical positions assessed fibreoptically,oropharyngeal leak pressure,the peak pressure of airway before(T₀)and after pneumoperitoneum（T₁）,and postoperative complications（sore throat,hoarseness,difficulty swallowing,reflux and aspiration）were record.Results:（1）Comparison of the general information.There was no significant difference in age,gender,height,weight,BMI,and ASA between the two groups（p>0.05）.（2）Comparison of PLMA insertion situation.All patients were successfully inserted PLMA.The first attempt success rate of the PLMA in group A and group B were 93%and 83%,respectively.The OLP of group A（25.5±5.4cm H₂O）was smaller than that of group B（28.8±4.9cm H₂O）,the difference was statistically significant（p=0.01）.The difference was statistically significant in PLMA size selection（p<0.05）.The number of insertions,ease of PLMA insertion and gastric tube and FOB score were comparable in group A and group B（p>0.05）.（3）Comparison of peak airway pressure during operation.There was no significant difference between T₀or T₁in group A and group B（p>0.05）.However,there was different in T₀and T₁.Therefore,it can be considered that the laryngeal mask airway pressure at T₁is greater than that at T₀.（4）Comparison of postoperative complications.There was no difference between the two groups in terms of complications such as sore throat,hoarseness,difficulty swallowing,and reflux aspiration（p>0.05）.Conclusion:Gender-related method and weight-related method are all suitable for laparoscopic cholecystectomy.However the gender-related method can provide higher airway sealing pressure.And the postoperative complications were comparable in the two groups.