Mixed Results for Video vs Direct Laryngoscopy for Tracheal Intubations

Deborah Brauser

January 19, 2010

January 19, 2010 (Miami Beach, Florida) — First-attempt success rates during an endotracheal tube exchange (ETT) via an airway exchange catheter (AEC) are significantly higher when experienced clinicians use videolaryngoscopy (with the GlideScope) than when they use "blind" direct laryngoscopy (DL) (with the Macintosh Direct Laryngoscope) for patients with difficult airways, according to an ongoing evaluation study presented here at the Society of Critical Care Medicine 39th Critical Care Congress.

However, a second prospective and randomized study presented during the Congress found no significant differences in first-pass success rate, length of hospital stay, or in-hospital mortality between the same 2 techniques in patients in the emergency department.

Dr. Jeff Keck

"The [American Society of Anesthesiologists] guidelines suggest that maintaining continuous access to the airway during an ETT via AEC may optimize patient safety," said the presenter of the first study, Jeff Keck, MD, from the University of Connecticut and Hartford Hospital Departments of Anesthesiology. "In the difficult airway patient, a blind exchange over an AEC using direct laryngoscopy is currently the standard method."

His investigational team hypothesized that "combining the AEC with videolaryngoscopy might improve exchange safety due to visualization of the periglottic structures not typically seen in the difficult airway with conventional [DL]."

"Airway exchange is a high-risk endeavor," said Dr. Keck during an interview with Medscape Critical Care. "Preoperative assessment or initial airway examination provide little information about the complexities one may face when asked to manage an instrumented airway following a prolonged intensive care unit course. For example, edema, cervical fixation devices, hemodynamic status, and positioning may all complicate the task."

Higher First-Attempt Success for Videolaryngoscopy

Using an ETT exchange database, Dr. Keck and his team identified 519 intensive care unit patients with grade 3 or 4 airways who underwent ETT with DL (n = 380) or with videolaryngoscopy (n = 139).

They measured the number of attempts, hypoxemia (defined as saturation of peripheral oxygen [SpO2] < 90%), severe hypoxemia (SpO2 < 80%), esophageal intubation, bradycardia (<40 beats per minute), aborted attempts, and method of rescue.

"The exchanges were performed by 2 anesthesiologist/intensivists [who were] very experienced in videolaryngoscopy and airway catheter exchange," explained Dr. Keck.

Results showed significant differences between the groups in first-attempt success (100% for the videolaryngoscopy vs 75% for DL) and in hypoxemia (5% vs 21%, respectively; 52% of these DL patients were deemed severely hypoxic).

DL was aborted in favor of another approach in 14 patients for inadvertent AEC removal and in 2 patients when the AEC coiled with their ETT passage. Of these, 12 were rescued with intubation of the laryngeal mask airway, 1 with videolaryngoscopy, and 1 with cricothyroidotomy.

Errant AEC removal occurred in only 3 of the videolaryngoscopy patients, with the technique acting as its own rescue.

Bradycardia developed in 31 of the DL patients (8.3%, with 70% of those related to severe desaturation) and esophageal intubation occurred in 4 (1.1%); none of the videolaryngoscopy patients experienced either occurrence.

Finally, although videolaryngoscopy allowed uncomplicated exchanges in 4 patients when their AEC could not be passed via the existing ETT, it could not be placed in 5 other patients and the power source failed twice.

"Overall, videolaryngoscopy is a valuable adjunct for ETT exchange, but sole reliance on this method is likely not prudent, and other contingencies must be available," said Dr. Keck during his presentation.

Later, he said that videolaryngoscopy provides "an extremely useful tool to visually monitor the process, allowing for increased safety. We are surprised that its use has not become more widespread."

"The take-home message is that videolaryngoscopy in experienced and prepared hands will decrease the incidence of complications and improve outcomes for airway catheter exchanges," said Dr. Keck.

However, he reported that there are instances when this technique is inappropriate, such as in inexperienced hands. "It does have a learning curve associated with it, but it would not take long, with regular usage, to acclimate to its subtle nuances. Additionally, limited mouth opening can be somewhat challenging because of the larger wand covering, but this is not a frequent problem."

He reported that the next step for his team is to evaluate multiple videolaryngoscopic devices in a randomized prospective trial. "We have teased out many interesting nuances from the airway database, many of which have led to further investigation, already in progress. The uses of videolaryngoscopy in the [intensive care unit] seem only limited by our imagination."

Study 2: No Significant Differences Found

In the second study, investigators examined, in a randomized prospective manner, the differences between GlideScope videolaryngoscopy and Macintosh Direct Laryngoscope in terms of intubation duration, success rates, and outcomes, such as hospital length of stay, in-hospital mortality, and discharge Glasgow Coma Scale (GCS).

Dr. Dale Yeatts

The results were presented by Dale Yeatts, MD, from the R. Adams Cowley Shock Trauma Center at the University of Maryland School of Medicine in Baltimore.

A total of 405 patients requiring emergent airway management in the emergency department at Cowley (a level 1 trauma center) were enrolled over 10 months and assigned to intubation with either the videolaryngoscopy (n = 200) or DL (n = 205).

"Here, intubations are performed by emergency medicine and anesthesia residents under the supervision of a senior anesthesiologist," explained Dr. Yeatts. "Although we did not go back and do a skills evaluation on those performing the intubations, the residents, more or less, had had exposure to both types of intubation techniques before our study. However, I think they had a limited amount of trauma exposure overall."

Results from this study showed a 75% first-pass success rate for both techniques. In addition, no significant differences were found between the groups for length of stay (7.9 ± 9.6 vs 9.4 ± 13.1 days for the videolaryngoscopy and DL patients, respectively), in-hospital mortality (9% vs 7.8%, respectively), and discharge GCS (13.3 ± 3.8 vs 13.2 ± 3.8, respectively.)

However, the mean intubation duration was significantly longer for the videolaryngoscopy group (69 seconds; 95% confidence interval [CI], 61.6 - 76.4) than for the DL group (57 seconds; 95% CI, 50.3- 63.7; P < .013).

"To our knowledge, this is the first randomized clinical trial comparing rapid sequence intubation with [videolaryngoscopy] and direct laryngoscopy in the emergency setting," said Dr. Yeatts. "While [videolaryngoscopy] may offer advantages not measured in our study, such as educational value as a teaching tool, we observed no objective difference in outcomes between the groups, and it did not improve first-pass success rates in our emergency trauma intubations.

"Still, it wasn't necessarily associated with worse outcomes," noted Dr. Yeatts, "so I think that it's worth further investigation. The GlideScope certainly offers a lot of promise. Should it be considered as first-line therapy or as a replacement to standard of care? We haven't found that to be the case yet."

He said that the investigators haven't gone back yet to evaluate whether a certain patient population did better or worse with either technique. "Obese patients, those with small jaws, or others anticipated to be very difficult to intubate using direct visualization methods have already, to some degree, anecdotally been shown to do well with the GlideScope."

"I think that if we go back and look at further data and refine our study, we may find that there are certain cases where there is a potentially different outcome than what we have here," explained Dr. Yeatts. "But just taking patients as they come, we have not yet shown that one method is definitively better for intubating patients."

For Difficult Airway Patients: Videolaryngoscopy From the Get-Go

"Although you can't really compare these 2 studies directly, the investigators in the first one specifically focused on patients with difficult airways and found a higher first-attempt success rate with videolaryngoscopy than with the conventional method," said Critical Care Congress cochair Michael West, MD, PhD, FACS, FCCM, professor and vice-chair at the University of California-San Francisco and the chief of surgery at San Francisco General Hospital.

"Unfortunately, these findings are not quite as clean as [they would have been had they] focused on that patient population in a prospective randomized study," said Dr. West, who was not involved with either study. "I would definitely like to see the Maryland group tease out success rates in this particular population, if possible. I'd also be interested in looking at their data on second attempts to see if success rates diverged between the 2 techniques."

He added: "Between these 2 studies, I'd say that videolaryngoscopy definitely has a role to play. For people who have a difficult airway, it's a great technique to have, and probably ought to be made available in the [emergency department]. Having said that, it probably isn't something we need to use right now on everybody because it does take a little bit longer and it's probably going to be more costly."

"I think the take-away message is that although we shouldn't use videolaryngoscopy for everyone, we should use it, based on the first study, on the patients we know have a difficult airway right from the get-go. For them, there's just no reason to the take a chance with the other method," concluded Dr. West.

Dr. Keck, Dr. Yeatts, and Dr. West have disclosed no relevant financial relationships.

Society of Critical Care Medicine (SCCM) 39th Critical Care Congress: Abstract 104, presented January 10, 2010; Abstract 929, presented January 12, 2010.