Table 1.
Baseline Characteristics of Patients in the Training Cohort and the Validation Cohort
| Training Cohort (n = 558) | Validation Cohort (n = 544) | P Value* | |
|---|---|---|---|
| Preintubation patient characteristics | |||
| Age, yr | 58 (43–67) | 58 (44–69) | 0.32 |
| Male | 314 (56.3) | 336 (61.8) | 0.06 |
| Black | 160 (28.7) | 104 (19.1) | <0.001 |
| BMI | 26.3 (22.5–31.0) | 26.76 (23.03–31.32) | 0.41 |
| SpO2 | 100 (98–100) | 100 (97–100) | 0.66 |
| FiO2 | 0.65 (0.30–0.80) | 0.40 (0.21–0.70) | <0.001 |
| SBP | 129 (110–149) | 133 (114–154) | 0.014 |
| Receiving vasopressors | 74 (13.3) | 64 (11.8) | 0.45 |
| Glasgow Coma Scale score | 11 (7–14) | 10 (7–14) | 0.73 |
| APACHE II score | 17 (12–23) | 17 (12–22) | 0.79 |
| Primary diagnosis of trauma | 120 (21.5) | 76 (14.0) | 0.001 |
| Active medical conditions | |||
| Gastrointestinal tract hemorrhage | 50 (9.0) | 49 (9.0) | 0.98 |
| Acute encephalopathy | 403 (72.2) | 362 (66.5) | 0.04 |
| Hypoxemic respiratory failure | 244 (43.7) | 176 (32.4) | <0.001 |
| Hypercarbic respiratory failure | 77 (13.8) | 67 (12.3) | 0.47 |
| Characteristics of the intubation procedure | |||
| Difficult airway characteristics | |||
| Obesity† | 68 (12.2) | 54 (9.9) | 0.23 |
| Other difficult airway characteristic‡ | 91 (16.3) | 78 (14.3) | 0.36 |
| Preoxygenation method | |||
| Standard nasal cannula | 236 (42.3) | 150 (27.6) | <0.001 |
| High-flow nasal cannula | 78 (14.0) | 52 (9.6) | 0.02 |
| Nonrebreather mask | 310 (55.6) | 267 (49.1) | 0.03 |
| Bag mask, no ventilation | 31 (5.6) | 54 (9.9) | 0.01 |
| Bag mask, ventilation | 61 (10.9) | 70 (12.9) | 0.32 |
| Etomidate given for induction | 350 (62.7) | 408 (75.0) | <0.001 |
| Neuromuscular blockade with rocuronium | 291 (52.2) | 339 (62.3) | 0.001 |
| Straight laryngoscope blade or missing | 129 (23.1) | 54 (9.9) | <0.001 |
| Direct laryngoscopy on initial attempt | 129 (23.1) | 145 (26.7) | 0.18 |
| Operator had critical care specialty training§ | 209 (37.5) | 176 (32.4) | 0.08 |
| Prior intubations using a bougie | 10 (3–20) | 10 (5–20) | 0.002 |
| Randomized to bougie | 283 (50.7) | 273 (50.2) | 0.86 |
| Primary outcome: successful intubation on the first attempt | 465 (83.3) | 435 (80.0) | 0.15 |
Definition of abbreviations: APACHE = Acute Physiology and Chronic Health Evaluation; BMI = body mass index; SBP = systolic blood pressure; SpO2 = saturation of peripheral oxygen.
Data are presented as median (interquartile range) or n (%). Missing values: BMI, 65 (5.9%); APACHE II score, 4 (0.4%); SpO2 at induction, 41 (3.7%); SBP at induction, 41 (3.7%); highest FiO2 in prior hour, 25 (2.3%); Glasgow Coma Scale score, 11 (1.0%); bougie experience, 2 (0.2%).
Testing for difference P value is chi-square test for categorical variables and Wilcoxon rank-sum test for continuous variables.
As listed in the electronic health record at baseline.
Other difficult airway characteristics include: vomiting; witnessed aspiration; upper gastrointestinal bleeding; epistaxis or oral bleeding; upper airway mass, infection, or trauma; head and neck radiation; limited neck mobility; limited mouth opening; history of obstructive sleep apnea; other.
Reference: emergency medicine, anesthesia, or other.