Table 1 List of the studies included in the systematic review and their characteristics

Donald [16] 2009

Poisoned patients

Observational

Prospective

Non consecutive

ED

26

GCS ≤ 8

ED physicians

- Aspiration

- Hospital LOS

- Mortality

- Aspiration: none

- Hospital LOS: non-intubated group vs. intubated group (26 h vs. 5.4 days)

- Mortality: non-intubated group vs. intubated group (0 vs 1)

Duncan [8] 2009

Poisoned patients

Observational

Prospective

Consecutive

ED

73

GCS ≤ 15

ED physicians

- Aspiration

- Admission to ICU

- Aspiration: none

- ICU admission: 1 in GCS ≤ 8 group

- Hospital LOS: GCS ≤ 8 vs GCS > 8 (26 h vs 14 h)

Eizadi-Mood [17] 2009

Poisoned patients

Observational

Retrospective

n.a.

ED

155

GCS ≤ 12

ED physician

- Aspiration pneumonitis

- Aspiration pneumonitis: intubation (OR = 0.07; 95%CI = 0.01–0.49)

[GCS (OR = 0.43; 95%CI = 0.30–0.62)]

Montassier [18] 2012

Poisoned patients

Observational

Prospective

Consecutive?

PH and ED

72

GCS ≤ 8

PH and ED physicians

- Aspiration pneumonia

- Aspiration pneumonia: 9/13 (69.2%) in delayed ED intubation group vs. 6/34 (17.7%) ED intubation group (p = 0.002).

[GCS > 8 group vs GCS ≤ 8 group (6 [24%] vs 15 [31.9%]; p = 0.48)]

Nielsen [6] 2012

Non-traumatic unconscious patients

Observational

Retrospective

n.a.

PH

557

GCS < 9

PH physicians

- Intubation during hospitalization

- 64/557 (11%) patients remained unconscious to ED; 12 (2%) of these were intubated in the ED

Dietze [19] 2014

Gamma-hydroxybutyric acid overdose patients

Observational

Retrospective

n.a.

ED

335

GCS ≤ 8

ED physicians

- ED LOS

- Admission status

- ED LOS: intubated vs. non-intubated group + 41% (Exp B = 1.41, 95%CI = 1.19 to 1.65)

- Probability of hospital admission: intubated vs. non-intubated group (OR = 0.10, 95%CI = 0.02 to 0.65)

van Helmond [20] 2019

Gamma-hydroxybutyric acid overdose patients

Observational

Retrospective

n.a.

ED

158

GCS < 9

PH and ED physicians?

- Aspiration

- Major aspiration events were reported in 5 patients (2.4%; 95%CI: 0.8–5.5)

[2 required intubation (16.7%; 95%CI: 2.1–48.4)]

Davis [21] 2005

TBI

Observational

Prospective

Consecutive?

PH

412

GCS ≤ 8

EMS providers

- Pre-RSI hypoxia

- Aspiration

- Mortality

- Hypoxia: before RSI vs. after RSI (23.9% vs. 5.9%, OR 4.97, 95%CI = 3.07–8.07, p = 0.001)

- Aspiration: GCS ≤8 (χ² p = 0.14; AUC = 0.55)

- Mortality: GCS ≤8 (χ² p < 0.001 AUC = 0.58)

Irvin¹¹ 2010

TBI

Observational

Retrospective

n.a.

PH

10,948

GCS = 3

EMS providers?

- Mortality

- Mortality rate: hospital intubated vs. prehospital intubated group (35% vs. 62%; p < 0.0001)

Evans [22] 2011

TBI

Observational

Retrospective

n.a.

PH

197

TBI needed intubation

EMS providers?

- Pneumonia

- GCS score in pneumonia group vs. non-pneumonia group (7.9 ± 0.9 vs 9.9 ± 0.4 p = 0.04)

- Use of BVM in pneumonia group vs. non-pneumonia group (18 [56.3%] vs. 56 [34.0%]; p = 0.02)

Emami [23] 2019

TBI

Observational

Retrospective

n.a.

PH

21,242

GCS < 9

PH physicians

- Mortality

- Mortality: intubated vs. non-intubated group (42.2% vs. 30.0%, respectively). In patients < 15 years old (42.2% vs. 33.4%; p = 0.03)

Steuerwald [24]

2018

Mixed adult patients

Observational

Retrospective

n.a.

PH

161

Adults patients who required airways management

EMS providers

- Aspiration

- Aspiration: 59 cases (8%) in supraglottic device group vs. 91 cases (12%) in endotracheal tube group (p value = .359; relative risk = .841; 95%CI .329–2.152)

Tweed [12] 2018

Pediatric unconsciuous patients

Observational

Retrospective

n.a.

PH

104

Unconscious pediatric patients

EMS providers

- Oxygenation

- Mortality

- Inadequate oxygenation: 4% in intubated group; 9% in BVM patients; 32% in only oxygen group.

- Mortality:

Trauma patients: intubated vs. non-intubated group (RR 0.61 [95% CI, 0.35–1.06]; P = .082).

Non-traumatic patients: intubated vs. non-intubated group (RR 2.98 [95% CI, 1.18–7.56]; P = .021)