Comparison Between Three Supraglottic Airway Devices ProSeal Laryngeal Mask Airway, Air-Q LMA and Ambu AuraGain

In this study PLMA, Air-Q® and Ambu AuraGain were compared undergoing elective surgeries under general anaesthesia. Primary outcome measure was insertion time. Airway sealing pressure,ease of insertion, number of attempts,overall success rate, glottis view,number of attempts of gastric tube placement , hemodynamic parameters and complications were also compared.

After approval from the institutional ethical committee, 150 patients were studied in a randomised prospective study, designed to compare PLMA , Air-Q® and Ambu AuraGain .The period of the study was from nov 2016 to aug 2018. This study was conducted according to Good Clinical Practice standards and the Helsinki Declaration.

The American Society of Anesthesiologists (ASA) physical status I and II patients, between 18-65 years of age, weighing from 40 to 60 kg of either sex, undergoing elective surgical procedures of duration not more than 90 minutes were selected for the study. The exclusion criteria included patients with anticipated difficult airway (mouth opening of <2 finger, Mallampati Score 4, limited neck extension, history of previous difficult intubation), upper respiratory tract infections,airway related conditions such as trismus, trauma or mass, cervical spine disease, obese with body mass index (BMI) ≥25kg/m2 ,pregnant females, patients at risk of aspiration (full stomach, hiatus hernia, gastro-oesophageal reflux disease, emergency surgery)and laparoscopic surgeries. Neck movement was assessed as Class: I-No reduction in movement, II-1/3rd reduction, III-2/3rd reduction, IV-Complete reduction.

Following detailed pre-anaesthetic check-up, informed written consent was obtained from all patients fulfilling the required criteria.Patients were randomly allocated into three groups namely Group P(ProSeal,n=50) ,Group Q (Air-Q®, n = 50) and Group A (AuraGain™, n = 50) using computer-generated randomisation sequence. Participants were assigned to specific groups by the operating room nurse in charge.

After attaching the standard monitors(ASA recommended), patients were pre-medicated with injection midazolam 0.05 mg/kg, glycopyrrolate 0.2 mg, dexamethasone 4 mg and nalbuphine 0.02mg/kg intravenously. All patients were pre-oxygenated for 3 min, and anaesthesia was induced with injection propofol 2 mg/kg. Injection vecuronium 0.1 mg/kg was given for neuromuscular blockade.

PLMA or Air-Q® or AuraGain™ appropriate for weight or/and height was inserted as per the manufacturers guidelines.After successful insertion, the cuff was inflated with air according to the size and type of LMA as per manufacturers guidelines, to prevent audible and palpable air leak. An effective airway was confirmed by bilateral symmetrical chest expansion on manual ventilation, auscultation of breath sounds, square waveform on capnography. Devices were fixed with adhesive tape applied to the maxilla on one side of the patient's face and passed over and under the tube in a single loop before fixing to the opposite maxilla.

Anaesthesia was maintained with oxygen, nitrous oxide and isoflurane and intermittent positive pressure ventilation. Haemodynamic parameters[heart rate(HR), mean arterial pressure(MAP)]were monitored before and after the insertion of the device. A lubricated gastric tube was placed in the stomach through the gastric channel. At the end of surgical procedure, anaesthesia was discontinued and residual neuromuscular blockade reversed with injection neostigmine and glycopyrrolate, followed by device removal. Complication if any was noted.

Insertion time, number of insertion attempts, overall success rate, ease of insertion, airway sealing pressure, glottis view, number of attempts of gastric tube insertion, hemodynamic parameters (HR and MAP) preinduction, induction and 1,3,5 and 10mins post induction and complications were noted. One attempt was defined as insertion of the LMA between the teeth until the LMA will be deemed to be correctly placed and its cuff will be properly inflated. In case of insertion attempts, maximum of three attempts were allowed. An attempt was considered unsuccessful, if there was failure to negotiate the device beyond oropharynx, significant leak present (both audible and auscultatory) or inadequate ventilation with EtCO2>45 mmHg. Failure of a device was defined as three unsuccessful insertion attempts or inadequate ventilation. After failure of three attempts, intubation was performed using conventional rigid laryngoscopy and case was recorded as failed and also deleted from the study. The ease of insertion of device based on Visual Analogue Scale(VAS) was recorded.0 was considered the easiest insertion of device and 10 being the most difficult insertion.Insertion time was defined as time interval (in seconds) elapsed from insertion of LMA between the dental arches until the confirmation of successful ventilation determined by chest wall movement, auscultation of breath sounds and square wave capnographic curves and no oropharyngeal leak with peak airway pressure ≥ 20cmH2O, which was recorded by an independent observer.The airway sealing pressure was measured by closing the expiratory valve of the circle system at a fixed gas flow of 3 L/min and recording the airway pressure at which equilibrium is reached. At this stage, a leak at mouth and stomach was ascertained. Glottic viewing was assessed by insertion of the fibreoptic bronchoscope through the airway channel of the respective LMA.A maximum of two attempts were allowed for gastric tube placement. Its correct placement was confirmed by injection of air and epigastric auscultation or aspiration of gastric contents. Failure was defined as inability to advance the orogastric tube into the stomach within two attempts. Blood staining of the device and tongue, lip or dental trauma was noted. Incidence of laryngospasm or hypoxia (defined as oxygen saturation <92%), if any, in intra-operative period was noted and managed accordingly. In post-operative period, an investigator blinded to study asked the patients about the signs of sore throat, dysphagia and hoarseness of voice. Incidence of hoarseness and sore throat, whether present or absent, were enquired in 24 h post-operatively.

The primary outcome measure of the study was insertion time. Based on a previous study investigators found mean insertion time in PLMA group was 23.43 seconds and SD of 3.54. Based on that, taking alpha 0.05, β =0.90 and 25% difference between the means as significant, investigators calculated 47 patients were required in each group; hence, the sample size was increased to 50 patients each.

The data were recorded in a Microsoft Excel Spreadsheet and analysed using SPSS statistics software version 24 (IBM SPSS Inc., Chicago, IL, USA). Continuous numerical variables were presented as mean (standard deviation) and intergroup differences were compared using one-way analysis of variance with post hoc correction. Categorical variables were presented as ratio or as n (%) and inter-group differences were compared using Kruskall-Wallis test. The P< 0.05 was considered statistically significant.