a b s t r a c t

Objective: Current guidelines advocate prehospital Endotracheal intubation in patients with suspected se- vere head injury and impaired level of consciousness. However, the ability to identify patients with Traumatic brain injury in the prehospital setting is limited and Prehospital ETI carries a high complication rate. We in- vestigated the prevalence of significant TBI among patients intubated in the field for that reason.

Methods: Data were retrospectively collected from emergency medical services and hospital records of trauma patients for whom prehospital ETI was attempted and who were transferred to Rambam Health Care Campus, Israel. The indication for ETI was extracted. The primary outcome was significant TBI (clinical or radiographic) among patients intubated due to suspected severe head trauma.

Results: In 57.3% (379/662) of the trauma patients, ETI was attempted due to impaired consciousness. 349 pa- tients were included in the final analysis: 82.8% were male, the median age was 34 years (IQR 23.0-57.3), and 95.7% suffered blunt trauma. 253 patients (72.5%) had significant TBI. In a multivariable analysis, Glasgow Coma Scale>8 and alcohol intoxication were associated with a lower risk of TBI with OR of 0.26 (95% CI 0.13-0.51, p < 0.001) and 0.16 (95% CI 0.06-0.46, p < 0.001), respectively.

Conclusion: Altered mental status in the setting of trauma is a major reason for prehospital ETI. Although most of these patients had TBI, one in four of them did not suffer a significant TBI. Patients with a higher field GCS and those suffering from intoxication have a higher risk of misdiagnosis. Future studies should explore better tools for prehospital assessment of TBI and ways to better define and characterize patients who may benefit from early ETI.

(C) 2021

1. Introduction

traumatic brain injury is a major cause of death and Long-term disability, particularly among the young [1]. In the United States,

Abbreviations: TBI, Traumatic Brain Injury; ETI, Endotracheal Intubation; GCS, Glasgow Coma Scale; RHCC, Rambam Health Care Campus; EMS, Emergency Medical Services; ISS, Injury Severity Score; EMR, Electronic Medical Records; CT, Computed Tomography; MDA, Magen David Adom; IDF-MC, Israeli Defense Forces Medical Corps; HEMS, helicopter emergency medical services; ATLS, Advanced Trauma Life Support; CPR, Cardiopulmonary Resuscitation; SD, Standard Deviation; IQR, Interquartile Range; CI, Confidence Interval; ROC, receiver operating characteristics; AUC, Area Under the Curve; csTBI, clinically and/ or radiologically significant TBI.

* Corresponding author.

E-mail address: [email protected] (D. Epstein).

approximately 2.8 million people sustain TBI annually, over 56,000 die, and over 80,000 suffer from permanent Neurological sequelae [2]. In Europe, TBI cases account for over 1.5 million hospital admissions and over 57,000 deaths annually [3]. As the primary injury occurring at the time of impact cannot be mitigated, prehospital care of patients with suspected TBI focuses on preventing the secondary insults caused by hypoxia, decreased cerebral perfusion, and Intracranial hypertension [4]. Most current international guidelines advocate establishing a Secure airway as early as possible in patients with suspected severe TBI [5-7]. Endotracheal intubation in prehospital settings is a complex procedure associated with a high rate of complications, including longer scene and transport time, transient hypoxemia, aspiration, dental and vocal cord injury, endotracheal tube displacement, hypotension, and

https://doi.org/10.1016/j.ajem.2021.12.015

0735-6757/(C) 2021

even death [8-11]. On scene, vs. in-hospital, ETI increases the risk of pneumonia, sepsis, multi-organ failure, length of intensive care and hos- pital stay [12-15]. Furthermore, on-scene ETI is associated with in- creased intracranial pressure [16]. Thus, among patients with severe TBI, prehospital ETI is a controversial issue [17]. Some studies reported worse outcomes associated with prehospital ETI [13,14,18] while others found better survival rates and better neurological outcomes [19-22].

The ability to accurately diagnose severe TBI in the field is limited and relies primarily on clinical examination and Glasgow Coma Scale score. While GCS has been shown to correlate with head- injured patients’ outcomes, the accuracy of prehospital GCS estimation and its ability to reliably diagnose the presence of severe TBI have not been well established [23-25].

In this study, we aimed to determine the prevalence of significant head injury among adult patients who were intubated in the prehospi- tal setting for presumed severe TBI.

1. Materials and methods

The study was approved by the Institutional Review Board of Rambam Health Care Campus (RHCC), (approval number 0256-21- RMB-D). The need for written informed consent was waived due to the retrospective study design.

• 1. Study design and settings

This retrospective cohort study included all trauma patients for whom ETI was attempted on the scene or en route due to suspected se- vere TBI by the emergency medical services (EMS) and primarily admit- ted to RHCC between January 2014 and December 2020. RHCC is a 1000-bed tertiary academic medical center serving more than two mil- lion residents, located in Haifa, Israel. It is the only Level I trauma center in northern Israel. Over 4000 trauma patients are hospitalized in RHCC annually, and more than 20% of them are severely injured (Injury Sever- ity Score [ISS] > 16).

Patients were retrieved from the RHCC’s trauma registry. The data in the registry are recorded by trained trauma registrars under the super- vision of a trauma director (general surgeon) and trauma coordinator (registered nurse). The quality of the records is assured by the National Center for Trauma and Emergency Medicine Research [26]. Data regard- ing the patients’ history and treatment were extracted from the prehos- pital (EMS) reports, trauma registry, and Prometheus, RHCC’s integrated electronic medical records (EMR) system. Chart review was conducted following published methods for retrospective studies [27]. Using a structured form, two abstractors reviewed all the charts inde- pendently. The abstractors were trained to use the data collection in- strument to systematically abstract data from the medical records. One abstracter was responsible for abstracting the independent vari- ables (DE) while the outcomes were abstracted by another investigator (SR). Computed tomography (CT) scans were reviewed separately by a neuroradiologist who was blinded to the intent of the study.

• 1. prehospital treatment“>Prehospital treatment

Trauma casualties are evacuated to RHCC mainly by Israel’s national EMS, Magen David Adom (MDA), from four geographical regions with more than 20 primary stations and dispatching points. Apart from MDA, trauma patients admitted to RHCC are treated by a few smaller re- gional EMS systems (Hian, Haiat, Alzhraoi) and the Israeli Defense Forces (IDF) Medical Corps. RHCC also serves as a primary destination for Helicopter Emergency Medical Services (HEMS) of both MDA and the IDF.

In all the above EMS systems, trauma patients are managed accord- ing to the current Advanced Trauma Life Support (ATLS) protocols [5] and Brain Trauma Foundation guidelines [7]. Briefly, indications for

ETI in trauma patients include facial or neck injury directly compromis- ing the airway, burn injuries with actual or anticipated airway compro- mise, cardiopulmonary resuscitation (CPR), persistent hypoxia not corrected by supplemental oxygen, GCS < 9, a drop in GCS of 2 or more points during the evacuation, or agitation interfering with treat- ment or transport attributed to presumed head injury. Before ETI, the patients are preoxygenated with 100% oxygen and anesthesia is in- duced by either etomidate (0.2-0.3 mg/kg) or ketamine (2-3 mg/kg) combined with fentanyl (1 ug/kg) and/or midazolam (0.1 mg/kg). The doses are modified as dictated by the clinical condition of the patient. Neuromuscular blocking drugs are not permitted during ETI in any of the relevant EMS systems. Tube position is confirmed both clinically by auscultation and by capnography. In MDA HEMS, rocuronium bro- mide may be used during transportation, after tube position is con- firmed. Intubation rescue techniques differ between the different EMS services but include elastic bougie, video laryngoscopy, supraglottic air- way device, cricothyrotomy, and Bag-mask ventilation. In all EMS sys- tems sedation is maintained during transfer to the receiving hospital using midazolam, ketamine, and/or opiates. Heart rate, blood pressure, oxygen saturation, and end-tidal carbon dioxide are continuously mon- itored during transport. Treatment protocols for hypotension during transport include Intravenous boluses of isotonic crystalloid fluids. Freeze-dried plasma is available in civilian helicopters and military am- bulances, while packed cells (before July 2018), and low titer group O+ whole blood (after July 2018) are available in military helicopters [28]. Vasopressors are not routinely used in trauma patients in the prehospi- tal setting.

• 1. Emergency department treatment

On arrival at the receiving hospital, a printed report with a detailed description of the injury mechanism, vital signs, physical examination findings, and interventions is handed to the hospital trauma team. The information from this report, as well as the in-hospital clinical course, is recorded in the hospital’s trauma registry and RHCC’s EMR system.

In the emergency department, all patients are treated according to ATLS principles. After an initial assessment in the trauma bay, total body CT is performed in all stable multi-trauma patients. Head and cer- vical spine CT is performed in patients with an isolated head injury. In unstable casualties, extended Focused assessment with sonography in trauma (eFAST) is used to rapidly identify hemorrhage or other causes of hypotension. In these patients, whole-body CT is performed after ini- tial Damage control resuscitation at the discretion of the attending trauma surgeon.

• 1. Data collection and definitions

The study population included patients 18 years or older for whom ETI was attempted (either successfully or not) by EMS due to suspected severe TBI, as retrospectively extracted from the EMS report. We ex- cluded patients who had one of the following indications for ETI irre- spective of their neurological status:

1. CPR
2. Burns or inhalation injury
3. Non-traumatic medical conditions (e.g., Cerebrovascular events, epi- lepsy, hypoglycemia)
4. Face or neck injury compromising the airway
5. Persistent hypoxia not corrected by supplemental oxygen (oxygen saturation < 90%)
6. Severe hypotension, defined as systolic blood pressure < 80 mmHg
7. Other indications not related to TBI

Patients transferred from other hospitals were excluded as well. Fi- nally, we excluded patients for whom the indication for prehospital

ETI could not be determined from a careful review of the EMS report and RHCC’s EMR.

The primary outcome of the study was the presence of radiologically significant and/or clinically significant TBI (csTBI). Radiologically signif- icant TBI included any lesion found on head CT scan except solitary con- tusion <=5 mm in diameter; localized subarachnoid hemorrhage less than 1 mm thick; subdural hematoma less than 4 mm thick; isolated pneumocephalus; or a closed depressed Skull fracture not through the inner plate [29]. Clinically significant TBI was defined by the need for any neurosurgical intervention during the index hospitalization includ- ing ICP monitor placement or abnormal level of consciousness after extubation. Patients who had at least one of the above findings were considered to have experienced csTBI. Patients who had none of the above but who required prolonged intubation (>48 h), or who died, could not be assessed for significant neurological injury and were thus excluded from the analysis. All other patients were not considered to have experienced significant head trauma.

• 1. Statistical analysis

Patients’ characteristics were summarized with descriptive statistics. Mean (+-standard deviation, SD) and median [interquartile range, IQR] were used for the description of normally and non-normally distributed quantitative variables, respectively. Continuous variables were assessed for normality by using the Kolmogorov-Smirnov test. Normally distrib- uted values were compared by using independent samples Student’s t- test, whereas the Mann-Whitney U test was used for non-normally dis- tributed covariates. The ?2 test was used to analyze the differences be- tween categorical variables. Bivariate analysis was performed to assess candidate variables as risk factors for predefined outcomes, and the asso- ciations between potential risk factors and the presence of significant TBI were quantified by the odds ratio (OR) and 95% confidence interval (CI). Multivariate forward stepwise logistic regression was performed to as- sess the relationship between patient characteristics and the outcome. Variables were selected as candidates for the multivariable analysis based on the level of significance of the bivariate association (P < 0.1). Model discrimination was measured by using the receiver operating characteristics (ROC) derived area under the curve (AUC). Missing data were handled by using listwise deletion. We used all the available data from our databases within the study time frame. A P-value of 0.05 was considered statistically significant. Data analysis was conducted with Statistical Package for the Social Sciences, version 23.0 (IBM SPSS Statis- tics for Windows; IBM Corporation, Armonk, NY, USA).

1. Results

During the study period, there were 1651 admissions requiring trauma team activation. Nighty-nine patients were transferred from other hospitals and were excluded from the analysis. Of the remaining 1552 patients, intubation was attempted before admission in 45.3% (703 patients). Most of the intubations were successful (81.2%). As shown in the study flow chart (Fig. 1), 41 patients were excluded from the analysis due to non-traumatic etiology (mainly cerebrovascu- lar accident, 35/41), as determined by the clinical workup in the emer- gency department. Additional 279 patients were excluded due to indication for ETI other than neurological status (such as burns, hypox- emia, facial injury, and other indications - see Fig. 1), and four because the indication for ETI could not be determined from the documentation. After excluding 41 patients with non-traumatic etiology, 379/662 (57.3%) trauma patients underwent ETI due to an impaired level of con- sciousness and presumed severe TBI. The presence of clinically signifi- cant TBI could not be determined from the charts in additional 30 cases, which were thus not included in further analysis (see methods). The clinical and laboratory characteristics of the 349 patients in- cluded in the final analysis are presented in Table 1. Two hundred and eighty-nine patients (82.8%) were male and the median age of the

study population was 34 years (IQR 23.0 to 57.3). Most patients suffered from blunt trauma (95.7%, 334 patients) and 55% (192 patients) were injured during motor vehicle accidents. The transport time was longer than 30 min in 82.4% of cases (281 patients), and 41% (143 patients) were evacuated by HEMS. One hundred twenty-nine (37%) patients had a scene GCS of 3, 159 (45.6%) had GCS of 4-8, and 61 (17.5%) had

GCS > 8. Of the 61 patients with GCS > 8, 24 (39.3%) were intubated for a deteriorating level of consciousness and 37 (60.7%) were intubated for agitation, presumably caused by head injury. On admission to the ED, 269 of the 349 patients (77.1%) had an endotracheal tube in the tra- chea, 53 (15.2%) were ventilated by bag valve mask after failed intuba- tion, and 27 patients (7.7%) had Esophageal intubation. The two latter groups of patients were successfully re-intubated in the ED.

Of the 349 patients who underwent at least one prehospital ETI at- tempt, 253 (72.5%) had csTBI per our definition. The patients with csTBI did not differ from those without csTBI regarding gender, age, day and time of admission, injury mechanism, transport time, and pro- portion of patients evacuated by HEMS. Patients with csTBI were more likely to have a GCS of 3 on-scene and patients without csTBI were more likely to have GCS > 8 on-scene (Table 1).The prevalence of csTBI was 80.6% among those with GCS of 3, 73% among patients with GCS 4-8, and 54.1% among those with GCS > 8 (P < 0.001). Fifty per cent (12/24) of patients intubated due to prehospital neurological dete- rioration had csTBI. Among those intubated due to agitation, the preva- lence of csTBI was 54.1% (20/37). Alcohol intoxication was significantly more common (11.5% vs. 2.4%, P < 0.001) among those without csTBI. Patients with csTBI had higher ISS and New ISS, longer intensive care unit and hospital stay, and higher in-hospital mortality rates (Table 1). In a multivariate logistic regression analysis, only prehospital GCS > 8 and alcohol intoxication were significantly associated with a lower risk of csTBI with OR of 0.26 (95% CI 0.13 to 0.51, P < 0.001) and 0.16 (95% CI 0.06 to 0.46, P < 0.001), respectively, as shown in

Table 2. The AUC of the model was 0.65 (95% CI 0.6 to 0.7, P < 0.001).

Among the 849 patients for whom prehospital ETI was not attempted, 31% (263 patients) were intubated in the ED. The indication for ED ETI was GCS < 9 in 71 (27.0%) patients. For another 56 (21.3%) patients, hypoxemia (n = 39) and/or severe hypotension (n = 35) were the indications for ETI (with 18 patients experiencing both indica- tions). One hundred thirty-six patients were intubated due to other in- dications. The median ISS of patients intubated in the ED was significantly lower than the ISS of those intubated by EMS (26 [IQR 16 to 34] vs. 33 [IQR 25 to 45], P < 0.001), and they had comparable hospi- tal lengths of stay (14 [IQR 6 to 31] vs. 16.5 [IQR 3 o 31] days, P = 0.4)

and in-hospital mortality (10.3% vs. 13.8%, P = 0.24).

1. Discussion

In this study we demonstrated that 57.3% of trauma patients are intubated in the field solely due to impaired level of consciousness and suspected severe TBI. Among these patients, 27% did not suffer a csTBI per our definition. The prevalence of csTBI increased as the pre- hospital GCS decreased, with 80.6% among those with GCS of 3 having a significant head injury.

In the hospital, patients with established severe TBI are managed with ETI and mechanical ventilation to enable therapeutic interventions and prevent secondary brain injury. However, although advocated by most international guidelines, prehospital ETI and ventilation are con- troversial. [5-7,30] Randomized controlled trials and retrospective stud- ies revealed inconclusive results. Most of them concentrated on the effect of prehospital ETI on the outcome of patients with proven severe TBI. A meta-analysis comparing mortality among adult trauma patients undergoing prehospital ETI to those intubated in the emergency depart- ment found increased adjusted mortality rates in the prehospital ETI group [31]. These studies did not report the indication for ETI. Most caregivers would agree that ETI is essential in patients with airway or respiratory compromise not rapidly corrected by less invasive

Fig. 1. Study flow chart.

* Some patients fulfilled several exclusion criteria.

** Fifty-six patients were either hypoxemic and/or severely hypotensive.

EMS- Emergency Medical Services; ETI- endotracheal intubation; AW- Airway; SO2- Oxygen Saturation; TBI- Traumatic Brain Injury; GCS- Glasgow Coma Scale.

interventions such as supplementary oxygen or bag-mask ventilation; this population is most likely to benefit from properly conducted pre- hospital anesthesia and intubation, whether they have a TBI or not [32]. However, some patients with a significantly reduced GCS score may have intact airway reflexes and adequate oxygenation and ventila- tion. Despite the current controversy, these patients are often intubated due to presumed severe TBI as advocated by guidelines. [5,7]

GCS score is the main tool used in the prehospital settings to screen for significant head injury [7]. However, there are several potential pitfalls with the use of this score in prehospital settings. First, GCS was originally described as a Prognostic tool when measured several hours following the injury, after the primary resuscitation is accom- plished [33]. Second, GCS has poor interobserver reliability and limited predictive value regarding the injury severity as determined during

Table 1

Clinical and laboratory characteristics of 349 patients intubated before hospital admission by EMS due to suspected TBI included in the study.

	Total	Significant Traumatic	No Significant Traumatic	P-value
	(n = 349)	Brain Injury (n = 253)	Brain Injury (n = 96)
Demographics
Male gender, n (%)	289 (82.8%)	214 (84.6%)	75 (78.1%)	0.2
Age, median (IQR) (years)	34 [23 to 57]	34 [23 to 59]	33.5 [23 to 46]	0.5
Young adults (18-24 years), n (%)	73 (28.9%)	27 (28.1%)	73 (28.9%)
Adults (25-64 years), n (%)	133 (52.6%)	57 (59.4%)	133 (52.6%)
Seniors (>65 years), n (%)	47 (18.6%)	12 (12.5%)	47 (18.6%)	0.35
Prehospital parameters Weekday, n (%)	246 (70.5%)	173 (68.4%)	73 (76.0%)	0.2
Weekend, n (%)	103 (29.5%)	80 (31.6%)	23 (24.0%)
Arrived daytime (08:00-15:59), n (%)	145 (41.5%)	110 (43.5%)	35 (36.5%)	0.47
Arrived in evening (16:00-23:59), n (%)	140 (40.1%)	99 (39.1%)	41 (42.7%)
Arrived at night (24:00-07:59), n (%)	64 (18.3%)	44 (17.4%)	20 (20.8%)
Motor vehicle collision, n (%)	192 (5.05%)	139 (54.9%)	53 (55.2%)	0.76
Fall, n (%)	113 (32.4%)	83 (32.8%)	30 (31.3%)
Other blunt trauma, n (%)	29 (8.3%)	19 (7.5%)	10 (10.4%)
Penetrating trauma, n (%)	15 (4.3%)	12 (4.7%)	3 (3.1%)
Transport time from scene over 30 min, n (%)	281 (82.4%)	207 (81.8%)	74 (77.1%)	0.67
Evacuated by ambulance, n (%)	206 (59.0%)	151 (59.7%)	55 (57.3%)	0.78
HEMS evacuation, n (%)	143 (41.0%)	102 (40.3%)	41 (42.7%)
Prehospital GCS 3, n (%)	129 (37.0%)	104 (40.3%)	25 (26.0%)	<0.001
Prehospital GCS 4-8, n (%)	159 (45.6%)	116 (45.8%)	43 (44.8%)
Prehospital GCS > 8, n (%)	61 (17.5%)	33 (13.0%)	28 (29.2%)
Alcohol intoxication, n (%)	17 (4.9%)	6 (2.4%)	11 (11.5%)	0.001
Drug assisted intubation, n (%)	297 (85.1%)	216 (85.4%)	81 (84.4%)	0.95
Successful prehospital ETI, n (%)	269 (77.1%)	192 (75.9%)	77 (80.2%)	0.47
Clinical Course Injury Severity Score, median (IQR)	33 [25 to 45[	38 [29 to 45]	17 [5 to 26]	<0.001
New Injury Severity Score, median (IQR)	48 [29 to 57]	50 [43 to 66]	18.5 [6 to 29]	<0.001
ICU LOS, median (IQR) (days)	8.5 [2 to 21]	16 [6 to 23]	1 [0 to 2]	<0.001
LOS, median (IQR) (days)	16.5 [5 to 31]	22 [8 to 35]	5 [3 to 10]	<0.001
In-hospital mortality, n (%)	48 (13.8%)	47 (18.6%)	1 (1.0%)	<0.001

Statistically significant values (P < 0.05) are given in bold and italics.

IQR- Interquartile Range; HEMS- Helicopter Emergency Medical Services; GCS- Glasgow Coma Scale; ETI- endotracheal intubation; ICU- Intensive Care Unit; LOS- Length of Stay.

hospitalization [34]. Third, the ability of early GCS to predict the need for advanced neurosurgical care remains undetermined [25]. Although the main etiology for unconsciousness in multiple trauma casualties is TBI, the diagnostic value of GCS <= 8 for severe TBI has only a moderate cor- relation with the diagnosis of severe TBI (sensitivity of 56.1% and spec- ificity of 82.2%) [24]. Agitation is considered a sign of severe TBI [35]. However, one study found that among patients intubated due to com- bativeness or agitation, TBI was found in 50% [36]. In our study the prev- alence of significant TBI in these patients was similar (54.1%). Indeed, such behavior is most commonly described in the recovery period, not in the period immediately following the injury [37]. Trauma patients who are intubated because of combativeness, and not due to medical necessity, have longer lengths of stay, increased incidence of pneumo- nia, and poorer discharge status when compared with matched controls [36].

In our heterogeneous cohort that includes a variety of patients treated by paramedic and physician-staffed EMS during ground and air- borne transport, an impaired level of consciousness was a major indica- tion for prehospital intubation. Fifty-seven per cent of ETIs were performed in respiratory and hemodynamically stable trauma patients who did not suffer an injury jeopardizing their airway. We found that at least 27% of them did not have csTBI.. Our findings are consistent with the previous reports. Bernard et al [20]. found in a randomized controlled trial in Australia that among trauma patients with suspected TBI, GCS <=9, and intact airway reflexes, 22% did not have severe TBI (de- fined by a head Abbreviated Injury Scale above 3). In another random- ized controlled trial performed in the US, 28% of patients intubated due to suspected severe TBI were extubated and discharged home within 48 h. [23,38]

Although early ETI may be essential for safe and timely transport and evaluation of trauma patients, the effect of this intervention on the

clinical course has never been clearly determined. Moreover, urgent in- tubation is associated with a high incidence of complications and can limit the neurologic examination on admission, which is an important part of the clinical evaluation of trauma patients with possible head in- juries. Our study was not designed or powered to determine the bene- fits or risks of prehospital ETI. Tsur et al [39]., however, found that the survival of trauma patients did not differ among patients in whom pre- hospital attempts to secure a definitive airway were successful or not. The lack of association between the success in securing a definitive air- way and survival persisted after adjustment for injury characteristics. Furthermore, this study found that even when the provider deemed the patient requires a definitive airway and failed in securing one, most patients survived.

Some recent guidelines advocate against routine ETI in trauma pa- tients with a suspected head injury, impaired level of consciousness, but preserved oxygenation [40]. In patients with GCS > 8, the recom- mendation for ETI is even weaker [7]. In respiratory stable patients with acute alcohol intoxication and GCS < 9, ETI is not required in the majority of cases and the rate of severe complications (e.g. mortality or secondary intubations during monitoring) is rare [41]. However, even a Minor head injury in the setting of severe intoxication may be an indication for airway control during transport. The tools currently available to Prehospital providers to help delineate patients who may benefit from intubation are limited, and more data on optimal manage- ment strategies and their effects on the patient’s outcomes are required. Several limitations must be considered when interpreting our find- ings. First, this is a retrospective study relying on adequate documenta- tion from the prehospital and in-hospital providers, as abstracted by investigators not blinded to the study hypothesis. Although we re- viewed all the available data (EMS reports, admission notes, daily clini- cal reports, and trauma registry), the individual therapy decisions on-

Table 2

Results of univariable and stepwise multivariable logistic regression predicting presence of significant traumatic brain injury.

explore better tools for prehospital assessment of TBI and ways to better define and characterize patients who may benefit from early ETI.

Bivariate analysis Demographics

Significant Traumatic Brain Injury

OR (95% CI) P-value

Funding

This research did not receive any specific grant from funding agen- cies in the public, commercial, or not-for-profit sectors.

Male gender 1.54 (0.85 to 2.78) 0.16

Age, years

Youth (18-24 years) Adult (25-64 years)	- 0.86 (0.5 to 1.48)	- 0.59
Seniors (>65 years) Prehospital parameters	1.45 (0.67 to 3.14)	0.35
Weekdays	-	-
Weekends	1.47 (0.86 to 2.51)	0.16
Arrived ED during: Daytime (08:00-15:59)	-	-
Evening (16:00-23:59)	0.77 (0.45 to 1.3)	0.33
Night (24:00-07:59)	0.70 (0.37 to 1.34)	0.28
Motor vehicle collisions	-	-
Fall	1.05 (0.62 to 1.78)	0.84
Other blunt trauma	0.72 (0.32 to 1.66)	0.45
Penetrating trauma	1.53 (0.41 to 5.62)	0.53
Transport time from scene over 30 min	1.2 (0.65 to 2.21)	0.56
Evacuated by ambulance	-	-
HEMS evacuation	1.1 (0.69 to 1.78)	0.69
Prehospital GCS 3	-	-
Prehospital GCS 4-8	0.65 (0.37 to 1.13)	0.13
Prehospital GCS > 8	0.28 (0.15 to 0.55)	<0.001
Alcohol intoxication	0.19 (0.07 to 0.52)	0.001
Drug assisted intubation	1.08 (0.56 to 2.08)	0.82
Successful prehospital ETI	0.78 (0.44 to 1.39)	0.39
Multivariable analysis Prehospital GCS 4-8	0.63 (0.35 to 1.12)	0.11
Prehospital GCS > 8	0.26 (0.13 to 0.51)	<0.001
Alcohol intoxication	0.16 (0.06 to 0.46)	<0.001

Statistically significant values (P < 0.05) are given in bold and italics.

ED- Emergency Department; HEMS- Helicopter Emergency Medical Services; GCS- Glas- gow Coma Scale.

site could not be completely reconstructed in some cases and some pa- tients may have an indication for ETI not clearly reflected by the docu- ments. Second, we defined an absence of clinically significant head injury as an absence of radiological signs of such injury and a normal Neurological examination after extubation performed 48 h from admis- sion. A complete neurological examination is not always documented in these patients, therefore Diffuse axonal injury cannot be excluded in this population. However, the probability of such a rapid clinical improve- ment in patients with severe diffuse axonal injury is low [42]. The pres- ence of significant head injury could not be determined in 30 patients, if we assume that all of them had a clinically significant head injury, its prevalence will be 81%, while if none of them had such injury, its prev- alence will be 67% giving a range of 67-81%. Third, in our institution trauma patients are not routinely screened for alcohol intoxication, un- less clinically indicated. Therefore, the low incidence found in our co- hort may underestimate the actual prevalence of alcohol intoxication.

1. Conclusions

Although most of patients intubated in the field due to suspected se- vere TBI indeed suffer from csTBI, one in four of them did not have a clinically significant head injury. Patients with a higher field GCS and those with alcohol intoxication have a higher risk of misdiagnosis. The ability to accurately diagnose severe TBI in the prehospital environment is limited. Although a significant portion of trauma patients may require ETI for safe transport and treatment, there may be a subpopulation of spontaneously breathing and well-oxygenated trauma patients with suspected severe TBI who can be managed without ETI and who may benefit from evidence-based sedation protocols. Future studies should

Data statement

The data that support the findings of this study are available from the corresponding author, upon reasonable request.

Source of support and sponsorship

None.

Conflicts of interest

Aeyal Raz reports receiving consultant fees and research support from Medtronic and consultant fees from Neuroindex (none related to this work). All the authors declare that they have no conflicts of interest.

Presentation

Preliminary data for this study were presented as a poster presenta- tion at the 40th International Symposium on Intensive Care and Emer- gency Medicine, Brussels, Belgium, 31 August to 3 September 2021.

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