Table 2 Estimated odds ratios (with 95 % confidence intervals) for the risk of failure on the first intubation attempt, based on a mixed-effects logistic regression model with HEMS as a random effect (n = 1,200)

Intercept (reference odds)

1,200

0.09

(0.05–0.14)

–

0.18

(0.06–0.26)

–

Sex

0.92

0.88

 Female (ref.)

355

1

–

–

1

–

–

 Male

845

1.02

(0.68–1.54)

0.92

1.04

(0.67–1.57)

0.88

Age^a

<0.001

< .001

 Age₁₀

1,200

1.071

(0.960–1.193)

–

1.060

(0.946–1.189)

–

 Age₁₀-squared

1,200

0.916

(0.873–0.961)

<0.001

0.914

(0.871–0.960)

<0.001

Provider’s previous number of intubations

0.48

0.46

 > 1,000 (ref.)

587

1

–

–

1

–

–

 101–1,000

514

0.99

(0.61–1.55)

0.96

0.95

(0.58–1.55)

0.84

 26–100

74

1.19

(0.57–2.51)

0.64

1.24

(0.56–2.71)

0.60

 11–25

12

0.23

(0.03–1.85)

0.17

0.21

(0.03–1.71)

0.14

 0–10

13

1.43

(0.40–5.05)

0.58

1.08

(0.28–4.12)

0.92

Drugs administered

0.16

 Sedatives

1,057

0.57

(0.34–0.97)

0.05

0.53

(0.28–1.02)

0.06

 NMBA

1,110

0.67

(0.36–1.22)

0.21

0.82

(0.40–1.70)

0.60

 Analgesics/opioids

858

1.11

(0.70–1.76)

0.66

1.51

(1.88–2.59)

0.14

Trauma

0.95

0.98

 Non-trauma^b (ref.)

390

1

–

–

1

–

–

 Blunt trauma^c

763

0.93

(0.60–1.45)

0.75

1.05

(0.64–1.71)

0.84

 Penetrating trauma

47

0.93

(0.31–2.82)

0.90

0.98

(0.31–3.10)

0.97

Indication

0.30

0.41

 Decreased level of consciousness (ref.)

780

1

–

–

1

–

–

 Hypoxemia

46

1.41

(0.56–3.57)

0.47

1.14

(0.46–3.07)

0.78

 Ineffective ventilation

123

1.42

(0.74–2.69)

0.29

1.31

(0.72–2.68)

0.43

 Existing airway obstruction

25

0.74

(0.16–3.32)

0.69

0.81

(0.20–4.10)

0.79

 Impending airway obstruction

79

1.49

(0.71–3.13)

0.29

1.41

(0.68–3.13)

0.37

 Combative or uncooperative

101

0.30

(0.07–1.22)

0.09

0.28

(0.07–1.19)

0.08

 Relief of pain or distress

46

1.19

(0.40–3.56)

0.76

1.03

(0.35–3.29)

0.96