title: Conventional Versus Video Laryngoscopy for Tracheal Tube Exchange: Glottic Visualization, Success Rates, Complications, and Rescue Alternatives in the High-Risk Difficult Airway Patient.
abstract: BACKGROUND
  Tracheal tube exchange is a simple concept but not a simple procedure because hypoxemia, esophageal intubation, and loss of airway may occur with life-threatening ramifications. Combining laryngoscopy with an airway exchange catheter (AEC) may lessen the exchange risk. Laryngoscopy is useful for a pre-exchange examination and to open a pathway for endotracheal tube (ETT) passage. Direct laryngoscopy (DL) is hampered by a restricted "line of sight"; thus, airway assessment and exchange may proceed blindly and contribute to difficulty and complications. We hypothesized that video laryngoscopy (VL), when compared with DL, will improve glottic viewing for airway assessment, and the VL-AEC method of ETT exchange will result in a reduction in airway and hemodynamic complications in high-risk patients when compared with a historical group of patients who underwent DL + AEC-assisted exchange.
  
  
  METHODS
  Critically ill patients requiring an ETT exchange underwent DL-assisted pre-exchange airway assessment. If the DL-assisted pre-exchange assessment rendered a "poor view," these patients underwent a VL-based airway assessment followed by a VL-assisted ETT exchange procedure. The DL and VL pre-exchange assessments were compared. The attempts, complications, and rescue devices required for ETT exchange were analyzed. These exchange results were then compared with a historical control group of patients who (1) were classified as a poor view on DL-assisted pre-exchange airway assessment; and (2) underwent a DL + AEC-assisted exchange. The airway assessment and ETT exchange were performed by a board-certified anesthesiologist from the Department of Anesthesiology alone or with anesthesia resident assistance.
  
  
  RESULTS
  Three hundred twenty-eight patients with a poor view on initial DL examination underwent a subsequent VL with comparison of views with the 337 patients in the historical control group (DL + AEC). A majority (88%) had a "full or near-full view" on VL examination. The first-pass success rate for ETT exchange was greater in the VL group (91.5% vs 67.7% with DL; P = 0.0001) and the number of patients requiring 3+ attempts was lower (1.2% vs 6.8% with DL; P = 0.0003). A commensurate difference in the incidence of mild and severe hypoxemia, esophageal intubation, bradycardia, and the need for rescue airway device intervention was also observed with VL exchange procedures when compared with the historical DL + AEC group.
  
  
  CONCLUSIONS
  These findings support the hypothesis that VL may result in better glottic viewing for airway assessment and may permit the ETT exchange procedure to be performed with fewer airway and hemodynamic complications. Execution of the ETT exchange over an AEC was augmented by improved glottic visualization to allow more efficient and timely ETT passage. Multiple attempts to resecure the airway increased the number of exchange complications. VL + AEC exchange led to fewer attempts and is consistent with the recommendation of the American Society of Anesthesiologists Difficult Airway Task Force to limit laryngoscopic attempts and, as a consequence, decrease complications. A VL-based pre-exchange airway assessment may be a valuable procedure for both planning the exchange and uncovering unrecognized airway maladies, for example, partial or complete self-extubation.
authors.affiliation: From the *Department of Anesthesiology and Division of Critical Care Medicine (Surgery), Hartford Hospital, Hartford, Connecticut; and †Biostatistics Center, George Washington University, Rockville, Maryland.
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Mort
authors.forename: Barbara H
authors.initials: BH
authors.lastname: Braffett
mesh_terms: D000328:Adult; D000368:Aged; D001919:Bradycardia / Q000209:etiology / Q000503:physiopathology; D057785:Catheters; D016638:Critical Illness; D004867:Equipment Design; D005260:Female; D005931:Glottis / Q000033:anatomy & histology*; D006439:Hemodynamics; D006801:Humans; D000860:Hypoxia / Q000209:etiology; D007442:Intubation, Intratracheal / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D007828:Laryngoscopy / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D014741:Video Recording