CLINICAL INVESTIGATION

The Impact of Prehospital Intubation With and Without Sedation on Outcome in Trauma Patients With a GCS of 8 or Less Michael Hoffmann, MD,* Patrick Czorlich, MD,w Wolfgang Lehmann, MD,* Alexander S. Spiro, MD,* Johannes M. Rueger, MD,* and Rolf Lefering, PhD,z on behalf of TraumaRegister DGU of the German Trauma Society (DGU)

Background: Although unconsciousness (Glasgow Coma Scale [GCS] 3 to 8) necessitates intubation according national guidelines, there is a notable lack of evidence to support this approach. This study evaluates the impact on outcome of prehospital intubation with and without sedation in trauma patients with a GCS of r8. Methods: A retrospective cohort analysis of severely injured trauma patients registered in the TraumaRegister DGU of the German Trauma Society (DGU) from 2002 to 2013 was conducted. Only directly admitted patients alive on admission and with a GCS of r8 at the scene were included. The observed outcome was matched with the expected outcome deriving from the Revised Injury Severity Classification, version II (RISC-II). Furthermore, a Standardized Mortality Ratio (SMR) was calculated for various subgroups. Early neurological outcome was classified using the Glasgow Outcome Scale. Results: A total of 21,242 patients fulfilled the study inclusion criteria. A total of 18,975 patients (89.3%) received prehospital intubation. Intubation rates were continuously increasing with decreasing GCS score values. Difference between observed and expected mortality was lower in intubated patients (42.2% [95% confidence interval (CI), 41.5%-42.9%]; RISC-II prognosis 41.4%; SMR 1.020 [95% CI, 1.003-1.037]) compared with nonintubated (30.0% [95% CI, 28.1-31.9%] RISC-II prognosis 26.6% and SMR 1.128 [95% CI, 1.057-1.199]). Patients being sedated before intubation presented significant (P < 0.001) lower observed mortality (37.7% [95% CI, 36.7-38.7%], RISCII prognosis 39.0%, SMR 0.967 [95% CI, 0.951-0.983]) assoReceived for publication July 24, 2015; accepted December 16, 2015. From the Departments of *Trauma, Hand and Reconstructive Surgery; wNeurosurgery, University Medical Center Hamburg-Eppendorf, Hamburg; and zInstitute for Research in Operative Medicine (IFOM), Witten/Herdecke University, Cologne, Germany. M.H. and P.C. contributed equally and therefore share first authorship. M.H., P.C., and R.L.: designed the study. M.H., W.L., and R.L.: analyzed data. M.D. and J.M.R.: performed the literature search. M.H., R.L., and A.S.: interpreted data. M.H., P.C., and A.S.: wrote the manuscript. The authors have no funding or conflicts of interest to disclose. Reprints: Patrick Czorlich, MD, Department of Neurosurgery, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, Hamburg D-20246, Germany (e-mail: [email protected]). Copyright r 2016 Wolters Kluwer Health, Inc. All rights reserved.

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ciated with a less poor early neurological outcome compared with those being intubated without sedation. Conclusions: Observed outcome of prehospital intubated patients with a GCS of r8 seems less poor than predicted compared with nonintubated patients. Sedation before intubation might potentially decrease mortality and improve early neurological outcome. Further studies are required to clarify this issue. Key Words: Glasgow Coma Scale, intubation, ventilation, sedation, prehospital, traumatic brain injury (J Neurosurg Anesthesiol 2016;00:000–000)

ince its creation in 1974 by Teasdale and Jennett1 for the purpose of assessing the depth and duration of impaired consciousness and coma, the Glasgow Coma Scale (GCS) has become an universal tool for the quantification of altered levels of consciousness,2,3 a prognostic indicator, and a stratification tool advising treatment procedures at defined cut-off points.2,4 Previous studies have documented hypoxia in a substantial percentage of head-injured patients with an associated increase in mortality.5,6 Prehospital intubation seems to improve outcomes in more critically injured traumatic brain injury (TBI) patients.4 Furthermore, a potential mortality reduction has been shown for patients presenting a GCS of r8 having received additional physician care.7 This has resulted in aggressive field airway management protocol,6,8 which have not been entirely embraced without reservation.6,9 Although a GCS of r8 necessitates intubation is a universal concept in emergency medicine and trauma, there is a notable lack of evidence to support this approach.4,6,9 Recent studies have raised concerns that prehospital intubation might result in impaired outcome and documented an increase in mortality.4,10,11 The effect of sedation before intubation in patients with a GCS of r8 has been a matter of controversy and substantial data are still lacking.12 Unplanned emergent intubation is a potentially preventable adverse event associated with poor outcomes.13 Beside endotracheal intubation, recent studies have focused on the impact of prehospital ventilation on

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outcome.4,6,10 Subsequent data analysis has demonstrated that prehospital intubation is associated with high rates of inadequate ventilation. This factor might be a valuable component resulting in impaired outcome.4,6,10 The purpose of this study is to evaluate the impact of prehospital intubation with and without sedation on mortality and early neurological outcome in trauma patients with a GCS of 3 to 8 based on a large registry.

in the reduced data set and have therefore to be restricted to cases documented with the standard data set.

METHODS Trauma Register DGU of the German Trauma Society The TraumaRegister DGU (TR-DGU) of the German Trauma Society (Deutsche Gesellschaft fu¨r Unfallchirurgie [DGU]) was founded in 1993. The aim of this multicenter database is an anonymous and standardized documentation of severely injured patients. Data are collected prospectively in 4 consecutive time phases from the site of the accident until discharge from hospital: (A) prehospital phase; (B) emergency room and initial surgery; (C) intensive care unit; and (D) discharge. The documentation includes detailed information on demographics, injury pattern, comorbidities, prehospital and in-hospital management, course on intensive care unit, relevant laboratory findings including data on transfusion, and outcome of each individual. The inclusion criterion is admission to hospital via emergency room with subsequent intensive care unit (ICU)/intermediate care unit care or arrival at the hospital with vital signs and death before admission to ICU. The infrastructure for documentation, data management, and data analysis is provided by AUC— Academy for Trauma Surgery (AUC—Akademie der Unfallchirurgie GmbH), a company affiliated to the German Trauma Society. The scientific leadership is provided by the Committee on Emergency Medicine, Intensive Care and Trauma Management (Sektion NIS) of the German Trauma Society. The participating hospitals submit their data anonymously into a central database via a web-based application. As the TR-DGU is a compulsory tool for quality assessment in certified trauma networks, no informed consent is required for data collection. Scientific data analysis is approved according to a peer-review procedure established by Sektion NIS. The participating hospitals are primarily located in Germany (90%), but a rising number of hospitals from other countries contribute data as well (actually hospitals from Austria, Belgium, Finland, Luxembourg, Slovenia, Switzerland, The Netherlands, China, and the United Arab Emirates participate). Currently, approximately 35,000 cases from >600 hospitals are entered into the database annually. Participation in the TR-DGU is voluntary except for hospitals associated with TraumaNetzwerk DGU. Network hospitals could choose a reduced documentation with about 40 items per case, whereas the standard documentation consists of about 100 items. Some variables evaluated in this paper were not available

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Study Design and Selection of Participants Only European patients treated between 2002 and 2013 with a complete documentation of intubation and GCS recorded prehospital by an emergency physician at the scene before resuscitation were included in this study. Further inclusion criteria were complete outcome documentation in terms of survival to hospital discharge or death. Patients qualified for this analysis if the Injury Severity Score (ISS) was Z9, and the patient has been admitted directly from the scene to the participating hospital, that is, patients transferred in from another hospital were excluded (no prehospital data available). In addition, patients transferred out to another hospital within 48 hours were excluded as well as outcome status was unknown.

Expected Mortality As injury pattern and severity might be different in the subgroups the observed outcome was compared with a prognostic estimate derived from the Revised Injury Severity Classification, version 2 (RISC II) score.14 This score was developed and validated in the TR-DGU. It considers age, worst and second worst injury, head injury, GCS, pupil reaction and size, sex, preinjury American Society of Anestesiologists classification, mechanism (blunt, penetrating), base excess, coagulation (International Normalized Ration), hemoglobin, shock, and cardiac arrest for prognosis. The RISC II prognosis reflects the average expected hospital mortality rate in the TRDGU based on data from 2010 and 2011.

Definitions TBI was defined as a head abbreviated injury scale (AIS) score of Z3. Severe injuries were defined as an AIS of Z3 for any body region. Mortality was defined as any patient not surviving to hospital discharge. TBI and alteration of consciousness were scored using the GCS, coded: motor, coded 1 to 6; verbal, coded 1 to 5; eye, coded 1 to 4. Unconsciousness was defined as a GCSr8. According to the German Trauma Registry data acquisition guidelines, early neurological outcome was assessed at hospital discharge and classified in 5 levels using the Glasgow Outcome Scale (GOS): 1, dead; 2, vegetative state (unable to interact with environment; unresponsive); 3, severe disability (able to follow commands; unable to live independently); 4, moderate disability (able to live independently; unable to return to work or school); and 5, good recovery (able to return to work or school). A GOS of 4 and 5 indicated a good outcome. Prehospital level of injury estimation was evaluated by an emergency physician using the National Advisory Committee for Aeronautics (NACA) and a local score. The NACA score is coded: 0, no injury; I, minor disturbance; II, slight to moderate disturbance; III, moderate Copyright

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to severe, but not life-threatening disturbance; IV, serious incident where rapid development into a life-threatening condition cannot be excluded; V, acute danger; VI, respiratory or cardiac arrest; and VII, death. The LC is coded: 0, no suspected injury; 1, minor injury; 2, moderate injury; and 3, severe/critical injury. Intubated patients were classified into 2 subgroups: patients that received sedation before intubation and patients being intubated without sedation.

lower intubation rates (82.7% in patients 80 y and older of age). Patients being intubated at the scene by emergency physicians showed an approximately 3-fold higher mean regarding the number of prehospital procedures and reached the receiving hospital by a mean of 13.3 minutes later compared with their nonintubated counterparts. Furthermore, those patients being intubated at the scene were administered almost the double amount of fluid resuscitation and showed considerable higher rates of catecholamine administration, chest drain placement, prehospital cardiopulmonary resuscitation, and sedation. Intubation rates were higher in patients being transferred to the hospital by helicopter (97.5% and 84.3%, respectively). Patients being transferred to a level-2 and level-3 trauma center presented higher mortality compared with those being admitted to a level-1 trauma center. Intubated patients surviving until hospital discharge demonstrated an increase in intubation, ICU, and hospital admission days compared with those who died in hospital (Table 1). Reviewing the impact of prehospital intubation on subgroups (Table 3) in combination with the calculated RISC-II prognosis: SMR was significantly (P < 0.001) lower in patients aged 60 and more and in those presenting an ISS > 24. Early neurological outcome was assessed on hospital discharge (18.8 ± 22.7 d). Good outcome (GOS 4+5) was documented for 53.71% of patients presenting a GCS of r8 being not intubated with an associated death rate of 31.0%. Analyzing the intubated patient collective, patients being intubated without sedation presented highest death rates (66.6%) and lowest rates of good (GOS 4+5) early functional outcome (17.8%). Highest rates of good (GOS 4+5) early functional outcome were recorded for patients being sedated before intubation (38.9%) associated with lowest death rates (39.0%) (Fig. 3). The majority of patients presented with sluggish (3759; 34.9%) or fixed (3556; 33.0%) pupils combined with highest intubation rates (90.5% and 95.4%, respectively). Only 3462 (32.1%) patients showed brisk pupil reaction (intubation rate 85.6%). Regarding pupil size and motor response, the majority of patients demonstrated normal-sized pupils (13,273; 62.5%), with an intubation rate of 87.0%. Patients showing no motor response to stimuli (13,068; 61.5%) had an associated intubation rate of 93.8%.



Analysis Statistical analyses were performed using SPSS statistical software (version 22.0; IBM Inc., Armonk, NY). Data are presented as mean with SD plus 95% confidence intervals (CI) for continuous variables and as percentages for categorical variables. As a large number of data are presented, formal P-value calculation was avoided for all comparisons. Furthermore, the large number of cases from the registry allows focusing on clinically relevant differences rather than on formal significance. In selected comparisons, statistical tests, or alternatively a 95% CI, have been calculated; P < 0.05 were considered statistically significant.

RESULTS A total of 21,242 patients with a prehospital GCS of 3 to 8 and complete documentation were available for analysis. The female:male ratio was approximately 1:3. Patient and core injury characteristics are provided in Table 1. The majority of patients presenting a GCS of r8 on the scene received prehospital intubation (18,975, 89.3%). Within this collective GCS = 3 was documented for 11,776 patients (55.4%). Intubation rates were continuously increasing with decreasing GCS score values (Fig. 1). The ISS, New ISS as well as the 24-hour (early) and hospital mortality were higher in intubated patients. But, comparing observed and expected mortality on the basis of the RISC-II prognosis, difference between observed and expected mortality was lower in intubated patients (42.2% [95% CI, 41.5-42.9%]; RISC-II prognosis 41.4%; Standardized Mortality Ratio (SMR) 1.020 [95% CI, 1.003-1.037]) compared with nonintubated (30.0% [95% CI, 28.1-31.9%], RISC-II prognosis 26.6%, SMR 1.128 [95% CI, 1.057-1.199]). Patients being sedated before intubation presented significant (P < 0.001) lower observed mortality (37.7% [95% CI, 36.7-38.7%]; RISC-II prognosis 39.0%; SMR 0.967 [95% CI, 0.951-0.983]) associated with a less poor early neurological outcome compared with those being intubated without sedation (64.8% [95% CI, 62.6-67.1%]; RISC-II prognosis 61.1%; SMR 1.061 [95% CI, 1.025-1.098]) (Fig. 2). Patients presenting with a TBI alone (isolated TBI) were less often intubated (82.2%) compared with patients showing combined injuries beside TBI (91.3%). In addition, patients suffering from isolated TBI demonstrated higher mortality compared with multiple injured patients (Table 2). Children and adults presented almost similar intubation rates (> 90%), whereas elderly persons presented up to 10% Copyright

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DISCUSSION The present study demonstrates that, compared with the RISC-II prognosis, observed mortality in patients presenting with a GCS of r8 was lower in intubated compared with nonintubated patients. Patients being sedated before intubation demonstrated lower mortality and improved early neurological outcome at hospital discharge. Regarding subgroups, patients aged 60 and more as well as severely injured trauma victims www.jnsa.com |

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TABLE 1. Basic Study Characteristics Parameters No. cases Standard documentation available (n [%]) Age Children (r15 y) (n [%]) Adults (16-59 y) (n [%]) Elderly (Z60 y) (n [%]) Males (n [%]) ISS (n [%]) New ISS (n [%]) 24 h mortality (n [%]) Hospital mortality (n [%]) GCS = 3 at scene (n [%]) Penetrating trauma (n [%]) Trauma mechanism (n [%]) MVC overall MVC vehicle MVC motorcycle MVC bicycle High fall (> 3 m) Low fall (< 3 m) Others Combined TBI (n [%]) Isolated TBI (n [%]) AISHead Z3 (n [%]) AISThorax Z3 (n [%]) AISAbdomen Z3 (n [%]) AISExtremities Z3 (n [%]) No. prehospital actions* Prehospital volume (mL) Time to hospital admission (min) Air transport (n [%]) Catecholamines* (n [%]) Chest drain* (n [%]) Prehospital CPR (n [%]) Sedation* (n [%]) Prehospital shock (BPr90 mm Hg) (n [%]) Shock on hospital admission (n [%]) HR on scene HR on hospital admission SpO2 (%)* on scene SpO2 (%)* on hospital admission Base excess Blood transfusion (until ICU) Intubated (d) survivor Intubated (d) nonsurvivor ICU stay (d) survivor ICU stay (d) nonsurvivor Hospital stay (d) survivor Hospital stay (d) nonsurvivor Assessment of Glasgow Outcome Scale (d)

Nonintubated

Intubated

Overall

2267 1466 (64.7) 52.6 (23.4) 86 (3.8) 1212 (53.5) 619 (40.4) 1564 (69.2) 24.0 (12.3) 32.6 (16.2) 348 (15.4) 680 (30.0) 591 (26.1) 102 (4.7)

18,975 14,217 (74.9) 46.2 (22.6) 873 (4.6) 12,179 (64.2) 4326 (30.1) 13,480 (71.4) 32.1 (16.0) 40.4 (17.8) 4954 (26.1) 8016 (42.2) 11,185 (58.9) 861 (4.7)

21,242 15,683 (73.8) 46.9 (22.7) 959 (4.5) 13,391 (63.0) 4945 (31.1) 15,044 (71.2) 31.2 (15.8) 39.6 (17.8) 5302 (25.0) 8696 (40.9) 11,776 (55.4) 963 (4.7)

841 (40.4) 296 (14.2) 136 (6.5) 217 (10.4) 312 (15.0) 761 (36.5) 182 (8.7) 1073 (47.3) 863 (38.1) 1790 (79.0) 678 (29.9) 170 (7.5) 330 (14.6) 1.1 (0.7) 663 (578) 56.8 (29.4) 193 (8.7) 46 (3.1) 6 (0.4) 42 (1.9) 498 (34.0) 253 (12.4) 229 (11.0) 89.1 (24.0) 89.5 (24.0) 93.2 (8.9) 94.8 (9.2)  3.4 (5.3) 263 (11.7) 6.6 (10.3) M = 1 3.8 (7.0) M = 1 10.9 (13.1) M = 6 4.5 (8.5) M = 1 22.0 (20.0) M = 17 6.0 (11.3) M = 2 17.2 (19.3) M = 12

10,701 (60.2) 4892 (27.5) 2131 (12.0) 1681 (9.5) 2888 (16.3) 2755 (15.5) 1624 (9.1) 12,238 (64.5) 4166 (22.0) 15,541 (81.9) 9258 (48.8) 2655 (14.0) 5044 (26.6) 2.9 (0.9) 1307 (933) 69.5 (28.8) 7597 (41.3) 3637 (25.6) 1184 (8.3) 2866 (15.1) 12,448 (87.6) 5271 (31.5) 4382 (25.3) 89.7 (33.4) 88.6 (27.6) 86.7 (20.1) 95.4 (12.5)  5.0 (6.3) 5035 (27.2) 12.0 (12.7) M = 8 3.2 (6.2) M = 1 17.8 (15.1) M = 15 3.4 (6.8) M = 1 29.5 (24.5) M = 24 4.6 (9.1) M = 2 19.0 (23.1) M = 13

11,542 (58.2) 5188 (26.1) 2267 (11.4) 1898 (9.6) 3200 (16.1) 3516 (17.7) 1806 (9.1) 13,311 (62.7) 5029 (23.7) 17,331 (81.6) 9936 (46.8) 2825 (13.3) 5374 (25.3) 2.7 (1.0) 1238 (923) 68.2 (29.1) 7790 (37.8) 3683 (23.5) 1190 (7.6) 2908 (13.7) 12,946 (82.5) 5524 (29.4) 4611 (23.8) 89.7 (32.6) 88.6 (27.3) 87.3 (19.3) 95.4 (12.5) 4.8 (6.2) 5298 (25.5) 11.2 (12.5) M = 7 3.3 (6.3) M = 1 16.9 (15.1) M = 14 3.5 (6.9) M = 1 28.6 (24.1) M = 33 4.7 (9.3) M = 2 18.8 (22.7) M = 13

Values in parentheses are percentages or SD. *Available only in the standard documentation. AIS indicates abbreviated injury scale; BP, systolic blood pressure; CPR, cardiopulmonary resuscitation; GCS, Glasgow Coma Scale; HR, heart rate; ICU, intensive care unit; ISS, Injury Severity Score; M, median; MVC, motor vehicle crash; TBI, traumatic brain injury.

(ISS > 24) being not intubated tend to have a worse SMR than predicted. Established trauma teachings describe a GCS of r8 as necessitating endotracheal intubation in recognition of high risk of secondary brain injury resulting from hypoxemia and hypercapnia caused by airway obstruction or respiratory compromise.15 Although the association between head injury, hypoxia, and poor outcome is undisputed, the efficacy of aggressive airway management remains unproven.4–6 Recent studies demonstrated

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that factors, such as trauma care organization, the training level of the emergency personnel, and response time may affect the beneficial impact of intubation on patient survival.16,17 Several retrospective studies revealed an increase in mortality associated with paramedic endotracheal intubation.4,6,18 Wang et al10 recently presented data from 1008 patients undergoing prehospital endotracheal intubation and 1223 patients undergoing endotracheal intubation in the emergency department, documenting an Copyright

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TABLE 2. Prediction of Mortality by Multivariate Logistic Regression Analysis Groups

FIGURE 1. Glasgow Coma Scale (GCS)-associated intubation rates. Bars presenting the intubation rate, squares representing the number of cases. Decreasing GCS score values are associated with continuously increasing intubation rates.

increase in mortality and a decrease of good outcome among patients undergoing prehospital intubation. In several countries, prehospital endotracheal intubation is often performed by ambulance paramedics, with minimal use of sedatives and muscle relaxants.16 This approach has been reported to be associated with a high risk of complications, such as failed intubation and hypoxemia.7,10,17,19 Especially the development of respiratory failure requiring an emergent unplanned intubation is a potentially preventable complication associated with increased morbidity and mortality.13 A risk index to identify these patients at risk might to reduce unplanned intubation associates mortality.13 Additional physician care has been shown to potentially reduce mortality in patients suffering

FIGURE 2. Mortality (bar with 95% confidence interval [CI]) and RISC-II prognosis (horizontal line) for intubated and nonintubated patients. RISC-II, Revised Injury Severity, Classification11; nonintubated mortality: 30.0% [95% CI, 28.1-31.9%], RISC-II prognosis 26.6%, SMR 1.128 [95% CI, 1.057-1.199]), intubated mortality: 42.2% [95% CI, 41.5-42.9%]; RISC-II prognosis 41.4%; SMR 1.020 [95% CI, 1.003-1.037]), intubated and sedated mortality: 37.7% [95% CI, 36.7-38.7%]; RISC-II prognosis 39.0%; SMR 0.967 [95% CI, 0.951-0.983], intubated and nonsedated mortality: 64.8% [95% CI, 62.6-67.1]; RISC-II prognosis 61.1%; SMR 1.061 [95% CI, 1.025-1.098], P = 0.0001. Copyright

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Coefficient

Trauma centre level (reference: level-1) Level-2 0.18 Level-3 0.63 Sedation (reference: status unknown) Nonsedated 0.03 Sedated 0.41 Intubation (reference: not intubated) Intubated 0.14 TBI (reference: not isolated) Isolated TBI 0.55 RISC-II score 0.88 Constant 0.01

OR [95% CI]

P

1.20 [1.08-1.32] 1.89 [1.37-2.56]

< 0.001 < 0.001

0.97 [0.84-1.11] 0.66 [0.60-0.73]

0.64 < 0.001

1.15 [1.00-1.32] 1.73 [1.58-1.88] 0.41 [0.40-0.42]

0.04 < 0.001 < 0.001 0.86

OR indicates odds ratio; RISC-II, Revised Injury Severity Classification, version II; TBI, traumatic brain injury.

from blunt trauma with a GCS < 9.7 Sedation before intubation requires pharmacological expertise. However, as a result of this study, intubation seems to be associated with a survival advantage and sedation prior intubation seems to be associated with a decrease in mortality and improved early neurological outcome at hospital discharge, although long-term neurological outcome data are not recorded in the TR-DGU database. Nevertheless this might advocate the need for further special training of medical emergency personnel. Concerns have been raised accepting a GCS score of r8 as a red line necessitating intubation.9,16 It is unclear, whether the association between prehospital intubation and increased mortality represents a form of selection bias or a true detrimental effect of early intubation on outcome.4 In previous studies the rate of prehospital intubation was substantially higher among patients with GCS scores between 4 and 8 versus a GCS score of 3, suggesting some form of selection bias.20 Results of the multivariate logistic regression analysis in this study suggest a higher mortality for intubated patients probably indicating this selection bias as intubation might represent a critically injured patient. ISS, New ISS, and a GCS of 3 on scene were considerably lower in the nonintubated patient collective. However, in this study we documented continuously increasing intubation rates with decreasing GCS score values from 8 to 3. Treatment strategies in terms of early intubation in isolated TBI remain a matter of controversy. Preventive measures, such as prehospital intubation are assumed to improve outcome in TBI.16,17 Early intubation of severely head-injured patients is one of the most fundamental aspects of TBI care.21 Recent studies revealed intubation to be associated with increased survival among the most critically injured patients.4,6,16 Winchell and Hoyt21 stratified patients by GCS score (3 vs. 4 to 8) and by isolated severe TBI versus multiple trauma based on AIS scores for other body systems. An absolute mortality benefit of over 20% was observed with prehospital intubation among patients with isolated severe TBI. In this study, intubation provides a survival advantage in trauma www.jnsa.com |

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TABLE 3. Mortality Distribution for Intubated Versus Nonintubated Patients in Subgroups Subgroups Isolated TBI Age 60+ Age <60 ISS 9-15 ISS 16-24 ISS > 24

Modus

n

Mortality (%)

Prognosis* (%)

Nonintubated Intubated Nonintubated Intubated Nonintubated Intubated Nonintubated Intubated Nonintubated Intubated Nonintubated Intubated

863 4166 969 5921 1298 13052 488 1992 648 3725 1131 13258

37.3 53.9 50.7 60.4 14.6 34.0 6.8 16.4 15.1 19.3 48.5 52.6

32.0 46.6 42.9 58.2 14.4 33.8 6.1 13.2 14.4 17.8 42.5 52.3

SMRw 1.17 1.16 1.18 1.04 1.01 1.01 1.11 1.24 1.05 1.09 1.14 1.005

(1.07-1.27) (1.12-1.19) (1.11-1.26) (1.02-1.06) (0.88-1.14) (0.98-1.03) (0.74-1.47) (1.12-1.36) (0.86-1.24) (1.02-1.16) (1.07-1.21) (0.99-1.02)

*The prognosis is based on the Revised Injury Severity Classification, version II (RISC-II11). wOnly available in patients with standard documentation. ISS indicates Injury Severity Score; SMR, Standardized Mortality Ratio, with 95% confidence interval; TBI, traumatic brain injury.

patients with a GCS of r8. Furthermore, patients suffering from isolated TBI had a significant higher mortality compared with multiple injured patients. The majority of intubated patients received sedation before intubation (65.2%) effectuating a further decrease in mortality and an increase in good early neurological outcome compared with intubation without sedation. Interestingly, this effect was less distinct in patients suffering from isolated TBI alone. Patients with an ISS of Z25 as well as patients aged 60 tend to have a better outcome being intubated.

FIGURE 3. Glasgow Outcome Scale (GOS). The sample sizes: nonintubated n = 2193; intubated (all) (n = 18,431); intubated and sedated (n = 12,013), intubated and nonsedated (n = 1723), sedation status unknown (n = 4695). PVS indicates persistant vegetative state.

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Although hypoxia may be prevented by prehospital intubation, a recent systematic review showed that the benefits from prehospital intubation and mechanical ventilation after TBI are uncertain.4,6,14,16 Beside endotracheal intubation, the impact of ventilation on outcome seems of overriding importance,10 as inadequate ventilation might lead to impaired outcome masking the beneficial effect of endotracheal intubation. As has been demonstrated by several prior analyses, ventilation emerged as an important predictor of increased mortality, with both hyperventilation and hypoventilation associated with lower survival among intubated patients.4,6,10 This relationship was not found to be present among nonintubated patients, suggesting that spontaneously ventilating patients were appropriately correcting for metabolic disturbances, whereas intubated patients suffered harm from normocapnia.6 In this study, the intubated patient collective presented lower mean base excess values on hospital admission compared with those being not intubated. Again, observed outcome of prehospital intubated patients with a GCS of r8 was less poor than predicted compared with nonintubated patients and mean SpO2 values were considerably higher in the intubated patient collective. Patient data in this study derives from countries where trained emergency physicians provide prehospital trauma care. Again, additional physician care has been shown to reduce mortality in severely injured patients.7 Reviewing NACA and LC scores as well as pupillary parameters in combination with intubation rates, highest rates were documented in patients with highly pathologic diagnostic findings (eg, NACA V-VII). This might indicate a thorough examination and risk evaluation prior intubation by experienced emergency physicians. This might be related to the fact that patients at risk for unplanned intubation might be identified early leading to reduced mortality.13 Transferring the right patient into the right hospital is mandatory for patient outcome. In this study, patients being transferred to a level-2 and level-3 trauma center presented higher mortality compared with those being admitted to a level-1 trauma center. This might indicate Copyright

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J Neurosurg Anesthesiol



Volume 00, Number 00, ’’ 2016

that severely injured patients presenting a GCS of r8 should rather be transferred to a level-1 trauma center to benefit from a more complex trauma care set-up.

Limitations Studies based on registry databases may have incomplete and incorrect data, which may have affected the present results. Death in the present patient population may have been the result of several injury mechanisms. Patients who died at the scene or were dead on emergency room arrival were excluded from the study and therefore might have biased the results. The RISC-II score, which is used for expected mortality calculations in this study, was adjusted according to the observed mortality of patients included into the German Trauma Registry data set. The RISC-II score is clearly not validated for special subgroup analyses and results in these subgroups should be interpreted with precautions. Moreover, GCS, NACA, and LC score evaluation show interrater variability and might be influenced by the grade and training background, and the assignment of scores is likely to be subject to local conventions that were almost certainly not uniform and thus may have biased the study results in unforeseeable ways. Endotracheal intubation represents the gold standard.9 However, in cases where endotracheal intubation is impossible, alternative airway management devices might have been used and might have biased study results. The link between use of sedatives and good outcomes being an association rather than a causation could not been clarified with this study and might therefore represent a certain bias. Only patients alive on hospital admission are included into the German Trauma Registry. This also may have biased study results. Nevertheless, this study was based on a large prospective data set, allowing for comprehensive examination of the impact of prehospital intubation on outcome in patients presenting a GCS of r8. The TR-DGU data set allows only for early functional outcome evaluation and does not provide any data for long-term follow-up. Finally data and results presented in this study are only applicable for countries submitting data to the TR-DGU as the availability of a physician at the trauma scene differs from country to country, for example, in countries like the United Kingdom, Canada, or Australia medical emergency services are partly provided by paramedics.7,22

CONCLUSIONS Observed outcome of prehospital intubated patients with a GCS of r8 seems less poor than predicted compared with nonintubated patients. Sedation before intubation might potentially decrease mortality and improve early neurological outcome. Further studies are required to clarify this and other issues, such as the influence of drugs used for intubation, the effect of the experience of the intubating physician, and also the effect of other airway devices which could not have been answered using the TR-DGU data set.

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Impact of Prehospital Intubation and Sedation

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