Effect of Laryngeal Mask Cuff Pressure on Postoperative Pharyngolaryngeal Complications in Geriatric Patients

This study received permission from Dokuz Eylül University Medical Faculty Non-Interventional Ethics Committee and informed consent was obtained from the patients. Ninety patients above the age of 65 with American Society of Anesthesiologists (ASA) physiological classification group I-III, undergoing elective surgery and with indications for laryngeal mask placement participated in this prospective, randomized and double blind study.

Patients taken to the operating room were given standard monitoring (ECG, pulse oxymetry, non-invasive blood pressure) and BIS monitoring [BIS-Vista ™ (Aspect Medical Systems, USA)] before anesthesia induction.

After patients were preoxygenated with 6 L/min oxygen through a face mask for 3 minutes anesthesia induction was provided by 0.02 mg/kg midazolam, 1-2 µg/kg fentanyl and 1-2 mg/kg propofol. During respiration Airway was not used, unless there was ventilation difficulty with the face mask. Before insertion the laryngeal mask used in daily routine (Laryngeal Mask Unique® (LMU)) was lubricated with a water-based gel and the cuff was completely deflated. After induction when bispectral index (BIS) values were between 40 and 60 and sufficient chin relaxation was obtained for patients weighing less than 50 kg no. 3 LMU, for those between 50-90 kg no. 4 and for patients above 90 kg no. 5 LMU was inserted by an anesthetist with more than five years experience. The placement method was according to the manufacturer's instructions. All patients were respirated by a breathing circuit with heat and moisture filter.

After the laryngeal mask was inserted the cases were manually respirated so peak inspiratory pressure was less than 20 cmH2O and the cuff of both groups was inflated with a 20 ml injector until the leak sound ceased. To evaluate ventilation the capnogram showed square wave forms and the patients' chest movements were observed, in unsuccessful situations the procedure was repeated. During attempts depending on the patients' reactions and with the requirement of keeping BIS values between 40 and 60, an additional dose of 0.5 mg/kg propofol was administered.

After Laryngeal Mask was determined and when anesthetic depth was sufficient (BIS 40-60) the inner pressure of the LMU cuff was measured and recorded by a manometer (cuff pressure manometer, Rusch, Germany). Later groups were divided in two using a random number table. In the group with cuff pressure limitation (Group Pressure Limiting (PL), n=45) cuff inner pressure was held below 60 cmH2O (44 mmHg), while the routine group (Group Routine Care, n=45) pressure was only recorded.