difficult intubation Archives - The anesthesia consultant

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Physician anesthesiologist at Stanford at Associated Anesthesiologists Medical Group

Richard Novak, MD is a Stanford physician board certified in anesthesiology and internal medicine.Dr. Novak is an Adjunct Clinical Professor in the Department of Anesthesiology, Perioperative and Pain Medicine at Stanford University, the Medical Director at Waverley Surgery Center in Palo Alto, California, and a member of the Associated Anesthesiologists Medical Group in Palo Alto, California.
emailrjnov@yahoo.com

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The safe management of a difficult airway is the most important single skill for an anesthesiologist. Every critically ill patient is managed by the priority of A – B – C, or Airway – Breathing – Circulation. Just as the initial most important factors in real estate are location, location, location, the three initial important factors in a critically ill patient are airway, airway, airway. I’ve written previously on the American Society of Anesthesiologists 2022 modifications to their Difficult Airway Algorithm, on the importance of expert airway management, and on advice for avoiding lost airway lawsuits, but I haven’t discussed the economic consequences of each difficult airway patient.

A 2021 publication, “Factors and Economic Outcomes Associated with Documented Difficult Intubation in the United States,” by Moucharite et al, studied the economic cost of a difficult intubation in hospitalized patients. Using data from the Premier Healthcare Database, the study looked at adult patients with inpatient surgical admissions during 2016, 2017, and 2018. Patients in the difficult intubation group had average inpatient costs $14,468 higher than patients without difficult intubations. Patients in the difficult intubation group had average ICU (intensive care unit) costs $4,029 higher than patients without difficult intubations. For difficult intubation patients the mean hospital length of stay was 3.8 days longer and ICU length of stay was 2.0 days longer. All data were significant to a p value of < 0.0001.

In California where I practice, these numbers would be significantly higher. The mean cost of a single hospital day in California is $4181, and the mean cost of an ICU day is significantly higher.

The Moucharite study was a large retrospective review of 2,233,751 cases from hospitals in all parts of the United States. With 609 cases in the difficult intubation group and 2,233,142 cases in the non-difficult intubation group, the incidence of difficult intubation was only 0.027%. Difficult intubation patients were more likely be male, black, less than 65 years old, and have urgent or emergent admissions, obesity, cancer, congestive heart failure, COPD, renal disease, and had been treated in a teaching hospital or a hospital of 500 beds or more.

Moucharite wrote, “Difficult intubation has been associated with a variety of complications including oxygen desaturation, hypertension, dental damage, admission to the intensive care unit, and complications at extubation, as well as arrhythmias, bronchospasm, airway trauma, CICV (can’t intubate, can’t ventilate), and sequela of hypoxia (cardiac arrest, brain damage, and death). This was consistent with a 2011 study of difficult airways from the British Journal of Anesthesia which stated, “Obesity markedly increases risk of airway complications. Pulmonary aspiration remains the leading cause of airway-related anesthetic deaths. . . . Unrecognized esophageal intubation is not of only historical interest and is entirely avoidable. . . . prediction scores are rather poor, so many failures are unanticipated . . . the first-pass success rate of intubation in the operating room ranges from only 63% to 85% . . . and up to 93% of difficult intubations are unanticipated.”

The Moucharite study has limitations. It’s a retrospective study of economic Big Data, and there is no direct evidence for a cause-and-effect relationship between a difficult intubation and a more costly hospitalization. The study does not include data from electronic medical records, so we have no knowledge on all the comorbidities and complications of the difficult intubation patients. The study included only hospitalized patients, even though seventy percent of surgical procedures in the United States take place in ambulatory surgery centers and offices outside of hospitals. The reported incidence of difficult intubation is estimated to be 1.5–8.5% of the general population, but in the Moucharite study only 0.027% of patients were found to have difficult intubation. This discrepancy implies some patients in the Moucharite study were difficult intubations but may have been assigned to the non-difficult intubation cohort.

Note that all three authors of the Moucharite study are employees of Medtronic, a medical device company which manufactures the McGrath videolaryngoscope.

McGRATH VIDEOLARYNGOSCOPE

I expect Medtronic could cite the Moucharite study as evidence that a videolaryngoscope (such as a McGrath) is a crucial piece of equipment for avoiding expensive difficult intubation outcomes. Moucharite wrote that there is, “a need for clinicians who perform tracheal intubations to carefully consider options . . . several studies demonstrated the benefits of videolaryngoscopy [emphasis added] including a shorter time required for tracheal intubation, a higher rate of successful intubations.”

For the first look when intubating a patient, most anesthesia providers still use a traditional direct laryngoscope:

MAC 3 DIRECT LARYNGOSCOPE

If the direct laryngoscope does not enable a successful intubation, a reasonable second step is to switch to a videolaryngoscope such as the GlideScope, manufactured by Verathon:

GLIDESCOPE

or the C-MAC, manufactured by Karl Storz:

C-MAC

or the McGrath, manufactured by Medtronic:

McGRATH VIDEOLARYNGOSCOPE

In my experience the larger 6.4-inch screen on a GlideScope or the 5.9-inch screen on a C-MAC makes them superior videolaryngoscopes to the McGrath with its diminutive 2.5-inch screen.

Why use a direct laryngoscope in the initial intubation attempt rather than use a videolaryngoscope? A direct laryngoscope costs less than a videolaryngoscope. Most direct laryngoscopes blades are washed and reused. Videolaryngoscopes require a new disposable sleeve or blade for every case. In facilities with budget concerns, replacing all traditional laryngoscopes with videolaryngoscopes would be expensive. A McGrath costs about $2500 on eBay, and each new nonreusable blade cover costs about $10. A new GlideScope was $12,745 in 2017. A reconditioned GlideScope costs between $1000 and $10,000 on eBay, and each new nonreusable blade costs $38.

A 2022 study comparing direct laryngoscopy to videolaryngoscopy concluded that “videolaryngoscopy likely provides a safer risk profile compared to direct laryngoscopy for all adults undergoing tracheal intubation.” A recent review stated that, “Though videolaryngoscopes have been recommended for use at first attempt of intubation by most international airway guidelines, the universal use of videolaryngoscopes is still facing hurdles because of limited training opportunities, availability and high cost.”

Should a videolaryngoscope replace a direct laryngoscope for all initial intubation attempts? I don’t think so. The majority of intubations are straightforward and are successful with a Miller 2 or a Mac 3 direct laryngoscope. Should a videolaryngoscope be available as a back-up piece of equipment for every intubation? Absolutely. The ASA Difficult Airway Algorithm includes the possible use of a videoscope, and states,
“Consider the relative merits and feasibility of basic management choices: (consider) video-assisted laryngoscopy as an initial approach to intubation.” An anesthesia provider who initiates general anesthesia and intubation without an immediately available videolaryngoscope is in danger of not being able to follow the algorithm. The hospital I work in is stocked with either the GlideScope and the C-MAC both readily available for difficult intubations. The availability of a videolaryngoscope for either a first attempt or for backup attempts to intubate a difficult airway patient is vital.

Difficult airway cases can lead to malpractice claims. A 2009 study published in Anesthesiology showed that 2.3% of 2,211 anesthesia-related deaths in the United States from 1999-2005 were attributable to difficult intubation and failed intubation. A 2019 study from the Anesthesia Closed Claims Project database showed that the 102 difficult intubation closed malpractice claims from 2000 to 2012 included sicker patients (n = 78 of 102), emergency procedures (n = 37 of 102), and non-perioperative locations (n = 23 of 102). Preoperative predictors of difficult tracheal intubation were present in only 76% of the patients. Inappropriate airway management occurred in 71 patients. A “can’t intubate, can’t oxygenate” emergency occurred in 80 of the 102 claims, with a delayed surgical airway occurring in 39% of those cases. The authors wrote, “outcomes remained poor in recent malpractice claims related to difficult tracheal intubation. Inadequate airway planning and judgment errors were contributors to patient harm.”

In conclusion: Difficult intubations are a major anesthesia problem, because of: 1) the difficulty in identifying difficult intubation patients prospectively, 2) the medical comorbidities that occur with difficult airway patients, 3) the medical complications that can occur if difficult airways are mismanaged, 4) the dollar cost of increased healthcare utilization as reported in the Moucharite study, and 5) the potential medical-legal liability risk with each difficult intubation.