Table 1 Emergency department intubation characteristics among patients as per physiological difficult airway (presentation hypotension, hypoxia, metabolic acidosis pH < 7.3 and shock index  ≥.9)

Age (years)

52.2 (± 17.5)

53.6 (± 17.2)

49.3 (± 17.7)

< 0.001*

Age groups

< 45 Years

336 [32.9%]

189 [28.2%]

147 [41.9%]

< 0.001*

≥ 45 Years

685 [67.1%]

481 [71.8%]

204 [58.1%]

Gender

Male

634 [62.1%]

385 [57.5%]

249 [70.9%]

< 0.001*

Female

387 [37.9%]

285 [42.5%]

102 [29.1%]

Shifts

Morning (8AM-4PM)

330 [32.3%]

212 [31.6%]

118 [33.6%]

0.812

Evening (4PM-10PM)

292 [28.6%]

194 [29%]

98 [27.9%]

Night (10PM-8AM)

399 [39.1%]

264 [39.4%]

135 [38.5%]

Pre intubation Vitals

Median [IQR]

Systolic Blood pressure (mmHg)

130 (153 − 110)

125 (149 − 105)

136.5 (160 − 117)

< 0.001*

Diastolic Blood pressure (mmHg)

77 (90 − 62)

72 (88 − 60)

80 (92 − 70)

< 0.001*

Heart Rate

106 (122 − 88)

109 (124 − 90)

102 (120 − 84)

0.010*

Oxygen Saturations (%)

94 (98 − 81)

93 (98 − 79)

96 (98 − 88)

< 0.001*

Respiratory Rate

25 (32 − 20)

27 (32 − 20)

24 (30 − 20)

< 0.001*

Reasons for intubation

Coma

39 [3.8%]

24 [3.6%]

15 [4.3%]

0.584

Hypoxia

119 [11.7%]

81 [12.1%]

38 [10.9%]

0.550

Metabolic Acidosis

136 [13.3%]

101 [15.1%]

35 [10%]

0.023*

Anticipated Decline

147 [14.4%]

111 [16.6%]

36 [10.3%]

0.006*

Respiratory Distress

687 [67.3%]

501 [74.8%]

186 [53%]

< 0.001*

Polytrauma

24 [2.4%]

13 [1.9%]

11 [3.1%]

0.232

Isolated trauma

32 [3.1%]

17 [2.5%]

15 [4.3%]

0.130

Gunshot Injury

10 [1%]

4 [0.6%]

6 [1.7%]

0.086

Others

29 [2.8%]

22 [3.3%]

7 [2%]

0.239

Shock Index

< 0.9

587 [57.5%]

343 [51.2%]

244 [69.5%]

< 0.001*

≥ 0.9

434 [42.5%]

327 [48.8%]

107 [30.5%]

pH

≥ 7.3

444 [43.5%]

220 [32.8%]

224 [63.8%]

< 0.001*

< 7.3

577 [56.5%]

450 [67.2%]

127 [36.2%]

Induction agent

Ketamine

79 [7.7%]

61 [9.1%]

18 [5.1%]

0.024*

Propofol

306 [30.1%]

192 [28.8%]

114 [32.5%]

0.205

Etomidate

233 [22.8%]

164 [24.5%]

69 [19.7%]

0.081

Midazolam

492 [48.2%]

316 [47.2%]

176 [50.3%]

0.366

Paralyzing agent

Succinylcholine

632 [61.9%]

385 [57.5%]

247 [70.4%]

< 0.001*

Rocuronium

79 [7.8%]

47 [7%]

32 [9.1%]

0.233

Atracurium

293 [28.7%]

224 [33.5%]

69 [19.7%]

< 0.001*

HEAVEN Criteria

Hypoxemia

414 [40.5%]

309 [46.1%]

105 [29.9%]

< 0.001*

Extremes of Size

22 [2.2%]

13 [1.9%]

9 [2.6%]

0.514

Anatomic abnormalities

35 [3.4%]

24 [3.6%]

11 [3.1%]

0.709

Vomiting/Blood/Fluid

219 [21.4%]

183 [27.3%]

36 [10.3%]

< 0.001*

Exsanguination

17 [1.7%]

10 [1.5%]

7 [2%]

0.552

Neck Mobility issues

60 [5.9%]

47 [7%]

13 [3.7%]

0.033*