Four videos could not be analyzed due to poor image quality. The remaining 297 patients were successfully intubated (100%) with novices successfully intubating 95.2% patients with 79.1% first attempt success (Fig. 3, Table 1). 93.1% patients were intubated within 2 attempts and 84% in <2 minutes. The median total intubation time for novices was 73 seconds (mean, 78.42; SD, 34.41). Median time to visualize cords was 38 seconds (mean, 44; SD, 26.67) and the median time to insert tube was 30 seconds (mean, 34.34; SD, 20.13). There were no major complications from novices attempting intubations using the RFS. There were 2 instances (<1%) of the RFS tip entering the esophagus. Four percent (10) of the successful intubations took >3 minutes to complete. The anesthesiology attending took over the intubation in 3 cases where there was thought to be impending oxygen desaturation (1%) and in 11 cases where the novice made >3 unsuccessful passes without any improvement in his/her technique. In all 14 patients, the attending could successfully intubate in his first attempt with an average intubation time of 31.4 seconds (range, 11 to 75 s) (Table 2).
There were 68 unsuccessful attempts made by novices. Many of the patients were intubated in further attempts leaving only 14 patients as failed intubations by novices. In 75% of the unsuccessful attempts, the novice had difficulty in visualizing the vocal cords. The main factors influencing the ability to visualize cords (Table 3) were: (i) the inability to keep the tip of the RFS away from the mucosa (30%), (ii) unfamiliarity with the anatomy as seen through an endoscope (20%), and (iii) excessive airway secretions (10%). In other cases (25%), the novices faced difficulty in inserting the ET tube into the trachea mainly from (i) the novice having difficulty in navigating the tip of the scope into the trachea or below the epiglottis (30%) and (ii) difficulty sliding off the ET tube-size mismatch (8%). Four of the patients with >3 unsuccessful attempts by novices were awake intubations in predicted DAs. It was very obvious from the videos that the main reason for this was lack of ability to instill local anesthesia and inability of patient to tolerate attempts. These patients were successfully intubated by the staff anesthesiologist.
Anesthesia research related to DA or CA is inherently difficult to perform. DAs are difficult to predict and the elective surgery population has low incidence of DA- making it difficult to select patients for study. It would be unethical to study crashing patients with novices and therefore the ETIs in most studies are either performed by very experienced operators9 or actively exclude known or predicted DA cases21 or are performed on manikins that don't compare to actual intubation environments.
There are few limitations to our study. The novices performed intubations under the supervision of an experienced staff anesthesiologist who they were familiar with; although we did not actively exclude DAs, we also did not record the incidence of predicted or actual DA and, finally, we did not have controls. We assume that the incidence of DAs in this study would be similar to other elective surgery patient populations, that is, <7.5%.
Most importantly, this study helped us identify barriers to using this device in CA populations and helped us suggest improvements to the RFS. The incidence of these barriers to successful intubation also closely matches that found in other RFS studies.
From our observational study it seemed that the main issues that will arise from attempting to use the RFS for CA management would be airway secretions (inability to suction), hypoxemia (inability to oxygenate and slightly prolonged intubation times), ET tube-stylet size mismatch, loss of visualization from soft tissue on the lens, and difficulty in the awake patient (inability to instill lidocaine).
The difficulty arising from the novice’s unfamiliarity with the bronchoscopic view of the glottis should not be an issue with intensivists/bronchoscopists.
In the past, attempts to build working channels into the RFS have led to increased cost, increased turnaround times, and increased risk of infections.
We designed a single-use multilumen plastic sheath with a main lumen to house the RFS and 2 small external channels running along the length of the sheath (Fig. 4 and the instructional video, Supplemental Digital Content 1, http://links.lww.com/LBR/A85). The 2 working channels are used for providing continuous suction from one channel and apneic oxygenation and instillation of lidocaine or saline flushes through the other channel. The sheath also has a distal semirigid semicircular extension designed to allow lifting of the epiglottis and for keeping soft tissue from blocking the view obtained by the distal lens.
This multilumen sheath is designed to overcome all pitfalls associated with RFS/flexible bronchoscope-assisted ETI in CA patients:
Because of the extremely high incidence of unanticipated DA in the CA population, with equally high risk for disastrous complications secondary to low cardiopulmonary reserve, we should treat all patients with CAs as anticipated DAs.4,9,11–13 An intensivist frequently manages the DA plus CA scenario in a hemodynamically unstable patient.42,43 Advanced airway management tools best suited to a patients’ clinical situation might not be available or might have not been used enough (>20 intubations) by the intensivist to be effective.9
We identified the RFS as 1 of 3 advanced airway management tools proven to be effective in DA situations. Because of its similarity to bronchoscopy, the RFS has potential to be effective for CA management by intensivists. We then evaluated the RFS in the hands of novices and found the overall success rate, first attempt success rate, and median intubation time to be similar to other, more expensive, alternative tools in well-designed prospective trials.
We also identified many barriers to widespread use of RFS in CA situations and suggested a modification to the RFS by using a multilumen sheath that adds 2 working channels to the RFS. The modification adds the ability to provide local anesthesia, apneic oxygenation, and clear secretions from the airway and potentially overcomes all identified problems.
This modification could provide the intensivist with a stand-alone, portable, and easy to master CA management device and therefore should be clinically evaluated.44
The authors thank McKenzie Mayo, MD, Anesthesiology and Basel Altaqi, MD, Pulmonary and Critical Care for their contribution in the initial phase of this study.
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