Maximal Intracuff Volumes for the Cuffed Oropharyngeal Airway in Adults

To the Editor: The cuffed oropharyngeal airway (COPA) is a modified Guedel airway with an inflatable distal cuff that forms an airtight seal with the pharynx [1-3]. The volume of air required to form an effective seal is usually 30-40 mL for the size 10 and 40-50 mL for the size 11, but larger volumes may be required due to a poor seal. There are no published data about the safe maximal volumes that can be used. With ethical committee approval, we inserted 10 size 10 COPAs into female cadavers and 10 size 11 COPAs into male cadavers (age 60-80 yr, weight 55-90 kg). Cadavers were 6-24 h postmortem and had no pharyngeal pathology. The integrity of the cuff was checked preinsertion by inflation with 20 mL of air and visual inspection. The cuff was then fully evacuated, and the COPA was inserted/fixed according to the manufacturer's instructions [4]. Care was taken to prevent cuff damage during placement. The pilot balloon was attached via a three-way tap to a 10-mL syringe and a calibrated pressure transducer accurate to 5%. The cuff was inflated in 10-mL increments until the cuff ruptured (detected by sudden loss of intracuff pressure). Cuff rupture occurred in three size 10 COPAs when inflating from 50 to 60 mL and in two size 11 COPAs when inflating from 60 to 70 mL. The mean (range) in vivo intracuff pressure before rupture was 201 (162-237) cm H2 O. The remaining COPAs ruptured with volumes of 60-90 mL. The cuff was usually torn along its distal posterior surface. In terms of its mechanical integrity, we suggest that the maximal cuff volume for the size 10 COPA is 50 mL and for the size 11 COPA is 60 mL. Intracuff pressures should be maintained <150-200 cm H2 O. C. Keller, MD University of Innsbruck, Innsbruck, Austria J. Brimacombe, MB ChB, FRCA, MD University of Queensland, Cairns Base Hospital, Australia