Author: Michael Vlessides
Obstructive sleep apnea is an independent risk factor for difficult and failed intubation, a meta-analysis has concluded, and now there are odds ratios to prove it.
As researchers from the United States and Canada noted, although the general risk for difficult and failed intubation is very low, it can nevertheless contribute to a variety of adverse events, including increased risk for airway trauma, rapid desaturation, laryngeal injuries, unexpected ICU admission and even death. Patients with obstructive sleep apnea (OSA) present with their own set of unique challenges in this regard, including potential upper airway abnormalities such as a large tongue, overcrowding of the oropharyngeal structures, decreased upper airway diameter and larger neck circumference.
“Along with several other societies, the American Society of Anesthesiologists [has] already produced a consensus statement saying that necessary precautions should be taken while securing the airway for patients with OSA,” said Mahesh Nagappa, MD, an assistant professor of anesthesia and perioperative medicine at Western University’s Schulich School of Medicine & Dentistry, in London, Ontario. “Nevertheless, we’ve never had a firm number from a meta-analysis in terms of an odds ratio to say what the risk of difficult airway is in these patients.”
Diagnosing OSA Before Surgery Important
Reporting at the 2018 annual meeting of the International Anesthesia Research Society (abstract SM153), Dr. Nagappa revealed that with respect to difficult intubation, the meta-analysis found that OSA was associated with a 3.44-fold greater odds for the adverse event (pooled odds ratio, 3.44; 95% CI, 2.28-5.18; P<0.00001). Similarly, OSA patients were found to have a 3.39-fold greater risk for difficult mask ventilation than were their counterparts without OSA (pooled OR, 3.39; 95% CI, 2.74-4.18; P<0.00001).
The odds of combined difficult intubation and difficult mask ventilation were 4.12-fold greater in OSA than non-OSA patients (pooled OR, 4.12; 95% CI, 2.93-5.79; P<0.00001).
In contrast, LM airway failure rates did not differ significantly between OSA and non-OSA patients (pooled OR, 1.34; 95% CI, 0.70-2.59; P=0.38). “At least we know the LM airway can be used as a rescue measure in these patients when we are unable to secure the airway,” Dr. Nagappa told Anesthesiology News. These results were confirmed by Bayesian random-effects analysis.
The researchers then performed meta-regression and sensitivity analyses on a variety of subgroups, including study type, quality of the study, grouping of OSA patients and sample size. “And we found none of these made any impact on our final result,” Dr. Nagappa said. “Similarly, age, gender, [body mass index] and neck circumference did not impact our results.”
According to Dr. Nagappa, these results help shed light on the importance of appropriately diagnosing OSA patients prior to surgery. “There’s a three- to fourfold increase in the risk of difficult airway with OSA patients,” he noted. “If you look at the literature on litigation issues, it usually involved patients who could not be reintubated in the PACU. Clinicians could have performed a planned intubation very nicely in the OR, but the same patients end up in trouble when they stop breathing or desaturate during an emergency intubation. That’s when they suffer things like brain damage and hypoxic brain injuries. So there are legal implications as well.”
Given such potential for trauma, the researchers recommended vigilance to their peers. “If I’m intubating a patient with either diagnosed or undiagnosed OSA, I would make my best attempt on the first attempt,” Dr. Nagappa explained. “And since patients who receive intraoperative opioids have a risk of apnea in the PACU, I would opt for aggressive monitoring and have all the airway equipment ready in case the patient stops breathing. It can still be an easy intubation, but when the patient desaturates, the whole scenario changes.”
Girish P. Joshi, MBBS, MD, a professor of anesthesiology and pain management at UT Southwestern Medical School in Dallas, agreed that the data suggest patients with known or suspected OSA may be at a higher risk for difficult mask ventilation and/or difficult tracheal intubation. “Thus, it is prudent to be prepared for such eventualities with special equipment, such as a video laryngoscope.
“However, my concern is many anesthesia practitioners may misinterpret this study and perform unnecessary awake tracheal intubation, which has its own limitation in this patient population,” Dr. Joshi said. “The sedation/analgesia administered for awake intubations may cause airway obstruction and subsequent adverse consequences.”