Anesthesiologists should consider using a larger Ring, Adair and Elwyn (RAE) tube for patients with diagnosed obstructive sleep apnea (OSA) to prevent dislodgment during surgery, a new study suggests.
Obstructive sleep apnea is characterized by repetitive narrowing or collapse of the upper airway during sleep. Although the “precise mechanism of pharyngeal collapse is unclear,” it may be related to upper airway length (UAL), according to researchers from the Thomas Jefferson University Hospital, in Philadelphia. They conducted a retrospective study of patients with an International Classification of Diseases, Ninth Revision code for OSA treated at the Thomas Jefferson University Hospital Department of Otolaryngology – Head and Neck Surgery from 2000 to 2015 to determine whether there was a correlation between UAL on CT and the presence and severity of OSA.
The researchers initially identified 1,740 patient records. The final analysis included cervical spine or neck CT scans and polysomnograms of 40 patients, which is the gold standard for diagnosing OSA, according to Corey R. Herman, MD, lead study author and CA-3 resident at Thomas Jefferson University Hospital. The researchers compared the UAL, UAL adjusted for height, body mass index (BMI), sex and age of the 33 patients with a positive polysomnogram versus the seven patients in the control group.
Upper airway length was defined as the distance between the lower part of the hard palate bone to the upper part of the hyoid bone in the midsagittal plane on CT. The researchers chose this area because it is prone to collapse due to a lack of bony support.
“We found that male sex is a significant predictor for UAL,” Dr. Herman said. “BMI greater than 30 [kg/m2] and a positive polysomnography are both significant predictors for upper airway length divided by height ratio.”
The UAL in female patients was significantly lower (P=0.001). The researchers also found a positive correlation between UAL adjusted for height and a diagnosis for OSA compared with patients with a negative polysomnogram. They did not find a correlation between UAL and OSA severity.
“Given our results, we would recommend anesthesiologists to choose a larger than anticipated tube for patients with diagnosed obstructive sleep apnea,” Dr. Herman said. “We all use oral and nasal RAE tubes for ENT [ear, nose, throat] surgery, head and neck surgery, and they all have a preformed curve. So it’s important to choose a tube with an adequate length after the curve to prevent unintentional dislodgment during surgery.”
Dr. Herman suggested using a tube that is one-half size larger than would normally be used. He noted that this is a preliminary analysis, and further research is needed to determine the actual size tube anesthesiologists should use for patients with OSA. The findings were presented at the 2015 annual meeting of the American Society of Anesthesiologists (abstract A1230).