Identifying a child presenting with a difficult airway may not be quite as easy as pediatric anesthesiologists believe, according to a chart review by a Canadian research team. Investigators at The Hospital for Sick Children, in Toronto, found that nearly 20% of difficult airways were unanticipated and more than half occurred in patients with no such history, leading them to stress the importance of careful physical assessment.
Seeking to identify the incidence, common features and clinical management of difficult intubation, the researchers reviewed the anesthetic records of children (age range, newborn to 17 years) undergoing general anesthesia at the pediatric tertiary care center between December 2009 and December 2011. “We wanted to see if we could draw any conclusions from the data and what we could learn from it,” said Cengiz Karsli, MD, associate professor of anesthesia at the institution.
The researchers manually looked through 22,766 anesthesiology records. Cases with documented difficult airway (Cormack-Lehane grade 3 or 4) were identified and analyzed for incidence, demographics, airway history, physical assessment, airway management details and complications.
They found that 94 patients with difficult airway underwent 125 intubations; the resulting difficult airway incidence was 5 in 1,000 anesthetics. Adolescent patients aged 13 years and older were most likely to have a difficult airway (49%); infants less than 1 year old represented 21% of cases.
As Dr. Karsli reported at the 2015 annual meeting of the Canadian Anesthesiologists’ Society (abstract 82398), difficult intubation was anticipated in only 80.6% of cases. “We think we are pretty good at what we do,” he said. “Yet, we missed almost 20% of the difficult airway patients that we saw. So maybe we can fix something here.”
Furthermore, over half of the difficult intubation patients had a prior intubation with no history of difficulty. “So, you need to have a very high index of suspicion and be ready with Plan B, because clearly we regularly miss these patients,” Dr. Karsli explained. “It’s easy to be ready for a known difficult intubation, but how do we deal with the unanticipated ones?” Airway management in pediatric patients who had an unanticipated difficult airway is shown in the Figure.
Sevoflurane and propofol were used as induction agents at a similar frequency; rocuronium and remifentanil were administered to 31.2% and 22.4% of patients, respectively. Muscle relaxants were given in all except four of the 25 unanticipated difficult airway cases. In 76 patients (60.8%), spontaneous respirations were maintained for intubation.
Difficult airway management was accomplished in 91% of patients with tracheal intubation, 5.6% with a laryngeal mask airway (LMA), 1.6% with nasal prongs and 1.6% with a facemask. Direct laryngoscopy was the intubation method of choice among 53 patients with an anticipated difficult airway (42.4%). Four emergency tracheotomies and two rigid bronchoscope intubations were performed, each after one or more unsuccessful intubation attempts. Of the 38 intubations in patients aged 14 to 17 years, six intubations were performed awake after airway topicalization. Thirty-four patients (27.2%) were admitted to the pediatric ICU, two of which were unplanned.
In the end, what struck Dr. Karsli was the finding that anesthesiologists were caught unaware as often as they were. “I always thought you could spot a pediatric difficult airway at 50 paces,” he said. “But maybe that’s not true, based on what we found here. So, I think you need to be always ready with a back-up plan, even though the patient doesn’t have a history of difficult intubation, may not have a syndrome associated with it or may not look difficult.”
Susan Goobie, MD, assistant professor of anesthesia at Harvard Medical School and Boston Children’s Hospital, questioned the definition of difficult intubation used in the analysis. “Who’s the one making the diagnosis of a difficult intubation—resident, fellow or attending?” she pointed out. “The other important thing for me, in taking care of these patients, is knowing the outcomes in the 20% that were unanticipated difficult intubations. What were the adverse events? Are we doing our patients harm because we are not picking this up? Or are we safely dealing with these difficult intubations without any increased morbidity or mortality?”
“We know that there was staff involvem ent in every difficult intubation case,” Dr. Karsli said. “So a staff member made the call, even though a resident or fellow may have made the discovery.”
Regarding outcomes, no surgeries were cancelled. “In other words, we managed to get the airway secured or managed 100% of the time for operative patients,” Dr. Karsli said. Two deaths occurred, both in what he called “horribly sick patients.” He added, “I don’t know if what we did or didn’t do would have made any difference in those cases.”