Following each intubation, the operator completed a data collection form, which included the following information: patient demographics, occurrence of a failed prehospital intubation attempt, operator specialty, operator postgraduate year (PGY), indication for intubation, method of intubation, paralytic agent, sedative agent, reason for device selection, device(s) used, presence of difficult airway characteristics (DACs), number of attempts at intubation, outcome of each attempt, and occurrence of AEs.
Only patients undergoing orotracheal intubation in the ED were included in this study. This included patients who underwent unsuccessful attempts at intubation in the field. Methods of intubation included rapid sequence intubation (RSI), in which a paralytic agent was used; oral intubation, in which a sedative agent was used (SED); and oral intubation, in which no medications were used (OTI).
The operator had three options to choose from for the reason for device selection. If the intubation was a routine airway with no anticipated difficulty, then the device selection was marked “standard.” If the device was selected with the expectation of a difficult airway, the reason for device selection was “difficult.” If the operator was using the device to gain educational experience with the device, then it would be classified as “education.”
Standard preoperative difficult airway predictors have been shown to be challenging to apply in the emergency setting.8 (link),9 (link) Thus, we developed a list of DACs that were feasible for the operator to determine prior to intubation in an emergent setting by brief examination of the patient. These include the presence of cervical immobility, obesity, large tongue, short neck, small mandible, facial or neck trauma, airway edema, blood in the airway, and vomit in the airway.
An attempt at orotracheal intubation was defined as insertion of the laryngoscope blade into the oropharynx, regardless of whether an attempt was made to pass the endotracheal tube. Each attempt was documented with one of three possible outcomes: 1) successful tracheal intubation with no additional attempts required, 2) inability to intubate with additional attempt (s) required, or 3) inadvertent esophageal intubation with additional attempt(s) required. Successful intubation was defined as correct placement of the endotracheal tube in the trachea as confirmed by end-tidal CO2 capnometry, pulse oximetry, chest auscultation, observation of chest excursion, absence of epigastric sounds, and misting of the endotracheal tube.
Adverse events tracked in this study include the following: esophageal intubation, oxygen desaturation, witnessed aspiration, mainstem intubation, accidental extubation, cuff leak, dental trauma, laryngospasm, pneumothorax, hypotension, dysrhythmia, and cardiac arrest. Cricothyrotomy was not considered an AE as we considered it an alternative way to secure the airway (see Table 1 for definitions of these AEs).
The data forms were reviewed by the senior author (JCS). If the form had any missing data, it was returned to the operator for completion. If information on the form contained inconsistencies, the operator was interviewed by the senior author for clarification. The data forms were cross-referenced to professional billing and pharmacy records to identify any intubations performed without a corresponding data form. If an intubation was identified without a data form, the operator was given a data form to complete as soon as possible to ensure a maximal capture rate. During the study period, 93.8% of the airway forms were turned in at the time of intubation, and the remaining 6.2% were captured by cross-referencing, for an overall 100% capture rate.
The data were then entered into the electronic data-base program HanDBase 4.0 (DDH Software, Wellington, FL, www.ddhsoftware.com) for the Palm Pilot and iPad and were subsequently transferred to Excel for Windows 2010 (Microsoft, Redmond, WA). The primary outcome measures were the incidence of one or more AEs and the incidence of specific AEs.