Comparison of maximum positive end-expiratory pressure (PEEP) sustained without leak with cuffed and uncuffed second-generation supraglottic airway devices in paediatric patients: A prospective randomized controlled trial

Supraglottic airway devices (SADs) have become the preferred airway management method for children undergoing short surgical procedures under general anaesthesia (GA). They became an effective alternative to endotracheal intubation in providing effective ventilation/oxygenation and delivery of anaesthetic agents while minimizing respiratory complications.One of the limitations with use of the first-generation SGAs is its low-pressure seal which is often inadequate for mechanical ventilation (MV) with positive end-expiratory pressure (PEEP). The second-generation SADs with inbuilt gastric drain tubes have been demonstrated to form a more effective seal of the airway to prevent regurgitation and aspiration compared to first-generation SADs. They are available as both cuffed (ProSealTM) and uncuffed (i-gel®) devices.

Patients will be randomly divided into two groups by using a computer-generated random number table and the allocation concealment will be done by a sealed opaque envelope method that will be opened just before starting premedication.

GROUP U (uncuffed device)- Airway will be secured using proper size (as per manufacturer recommendation) with I gel SGA

GROUP C(cuffed device)- Airway will be secured using proper size (as per manufacturer recommendation) with Proseal SGA

On arrival of the patient in the OR, ASA standard monitors will be attached and baseline parameters including heart rate (HR), blood pressure (BP), peripheral oxygen saturation (SpO2), and respiratory rate (RR) will be recorded. The time of the last meal or fluid intake will also be recorded. The gastric ultrasound (GUS) will be done to evaluate presence of air in the stomach (an acoustic shadow phenomenon and/or a comet-tail artifact into the antrum defined the ultrasonographic diagnosis of presence of air into the stomach) as well as gastric contents and baseline gastric volume.

After baseline GUS, premedication intravenous (IV) fentanyl 2 µg/kg will be administered and preoxygenation with FiO2 1.0 using breathing circuit will be done. Induction of GA will be done using IV propofol 2-2.5 mg/kg and muscle relaxation will be facilitated using IV rocuronium 0.9 mg/kg. Positive pressure will be avoided to prevent gastric insufflation of air. Proper size SGA as per the manufacturer recommendation and allocated group will be inserted and connected to breathing circuit. Proper placement of the SGA will be confirmed by inserting a FOB through the breathing tube of the SGA and the Brimacomb score will be recorded. The Brimacombe scores of 4 or 3 will be considered as proper placement, whereas scores of 2, 1, or 0 will be considered as improper placement and reinsertion will be attempted for proper placement. The first attempt and overall success rate will be recorded.

Following the confirmation of proper placement of the SGA, MV will be initiated using volume-controlled mode with VT of 6 ml/kg, FiO2 of 1.0 and PEEP of 5 cmH2O keeping the maximum peak pressure limit at 30 cmH2O. Thereafter, PEEP will be increased by 2 cmH2O every minute and leak will be observed. For observing the leak, detection of EtCO2 in the oral cavity and detection of an audible noise by neck auscultation will be used. The PEEP at which the leak occur will be noted and the patient will be ventilated using the initial setting except the PEEP level just below the PEEP at which leak occur. The respiratory mechanics including PIP, plateau pressure (Pplat), compliance (Crs) and resistance (r) will be recorded at the ventilatory setting. Repeat GUS will be done to evaluate presence of air in the stomach as well as gastric contents and baseline gastric volume. In occurrence of haemodynamic instability with the high will be observed and recorded.

At the end of the surgery, the SGA will be removed, and the patient will be followed in the PACU and postoperative ward for occurrence of postoperative airway morbidities (POST, dysphagia, cough) and complications (PONV, laryngospasm, bronchospasm, desaturation etc).