Functional and long-term outcomes in severe traumatic brain injury following regionalization of a trauma system

Prehospital care for traumatic brain injuries: A review of U.S. state emergency medical services protocols

Traumatic brain injury (TBIs) necessitates a rapid and comprehensive medical response to minimize secondary brain injury and reduce mortality. Emergency medical services (EMS) clinicians serve a critical role in the management of prehospital TBI, responding during an initial phase of care with significant impact on patient outcomes. We used versions two and three of the Brain Trauma Foundation (BTF) Prehospital Guidelines for the Management of Traumatic Brain Injury and the NASEMSO National Model Clinical Guidelines to determine key elements for a TBI prehospital protocol and included common factors across sources such as recommendations concerning patient monitoring, hypoxia, hypotension, hyperventilation, cerebral herniation, airway management, hyperosmolar therapy, and transport destination. We then conducted a cross-sectional evaluation of publicly available statewide EMS clinical protocols in the US to determine the degree of alignment with national guidelines. We calculated descriptive statistics for each factor in the state protocols. Despite adoption of some evidence-based recommendations for a standard approach to the prehospital management of patients with TBI, we found significant variability in statewide EMS treatment protocols for management of severe TBI, especially in the recommended frequency of patient reassessment and for the management of suspected herniation. Most statewide protocols provided guidance regarding oxygenation, ventilation, and blood pressure management that aligned with evidence-based guidelines. While most protocols did address management of oxygenation and ventilation, one in four protocols had no specific guidance for managing hypoxia and only 31% of protocols recommended avoiding hyperventilation. For the management of suspected cerebral herniation, over half of statewide protocols recommended hyperventilation, whereas only 31% explicitly advised against hyperventilation regardless of TBI severity. Interestingly, 94% of protocols do not mention the use of hyperosmolar therapy for TBI patients, neither recommending use or avoidance of hyperosmolar therapy. In conclusion, we found inconsistent adoption of national recommendations in available statewide protocols for prehospital TBI management. We identified significant gaps and variation in statewide protocols regarding patient monitoring and reassessment, as well as in several key areas of severe TBI management.

Does the implementation of a trauma system affect injury-related morbidity and economic outcomes? A systematic review

BACKGROUND

Trauma accounts for a huge burden of disease worldwide. Trauma systems have been implemented in multiple countries across the globe, aiming to link and optimise multiple aspects of the trauma care pathway, and while they have been shown to reduce overall mortality, much less is known about their cost-effectiveness and impact on morbidity.

METHODS

We performed a systematic review to explore the impact the implementation of a trauma system has on morbidity, quality of life and economic outcomes, in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. All comparator study types published since 2000 were included, both retrospective and prospective in nature, and no limits were placed on language. Data were reported as a narrative review.

RESULTS

Seven articles were identified that met the inclusion criteria, all of which reported a pre-trauma and post-trauma system implementation comparison in high-income settings. The overall study quality was poor, with all studies demonstrating a severe risk of bias. Five studies reported across multiple types of trauma patients, the majority describing a positive impact across a variety of morbidity and health economic outcomes following trauma system implementation. Two studies focused specifically on traumatic brain injury and did not demonstrate any impact on morbidity outcomes.

DISCUSSION

There is currently limited and poor quality evidence that assesses the impact that trauma systems have on morbidity, quality of life and economic outcomes. While trauma systems have a fundamental role to play in high-quality trauma care, morbidity and disability data can have large economic and cultural consequences, even if mortality rates have improved. The sociocultural and political context of the surrounding healthcare infrastructure must be better understood before implementing any trauma system, particularly in resource-poor and fragile settings.

PROSPERO REGISTRATION NUMBER

CRD42022348529 LEVEL OF EVIDENCE: Level III.

Impact of lower level trauma center proliferation on patient outcomes

Background

In attempt to increase trauma system coverage, our state added 21 level 3 (L3TC) and level 4 trauma centers (L4TC) to the existing 7 level 1 trauma centers from 2008 to 2012. This study examined the impact of adding these lower-level trauma centers (LLTC) on patient outcomes.

Methods

Patients in the state trauma registry age ≥ 15 from 2007 to 2012 were queried for demographic, injury, and outcome variables. These were compared between 2007 (PRE) and 2008-2012 (POST) cohorts. Multivariate logistic regression was performed to assess independent predictors of mortality. Subgroup analyses were performed for Injury Severity Score (ISS) ≥15, age ≥ 65, and trauma mechanisms.

Results

143,919 adults were evaluated. POST had significantly more female, geriatric, and blunt traumas (all p < 0.001). ISS was similar. Interfacility transfers increased by 10.2 %. Overall mortality decreased by 0.6 % (p < 0.001). Multivariate logistic regression analysis showed that being in POST was not associated with survival (OR: 1.07, CI: 0.96-1.18, p = 0.227). Subgroup analyses showed small reductions in mortality, except for geriatric patients. After adjusting for covariates, POST was not associated with survival in any subgroup, and trended toward being a predictor for death in penetrating traumas (OR: 1.23; 1.00-1.53, p = 0.059).

Conclusions

Unregulated proliferation of LLTCs was associated with increased interfacility transfers without significant increase in trauma patients treated. LLTC proliferation was not an independent protector against mortality in the overall cohort and may worsen mortality for penetrating trauma patients. Rather than simply increasing the number of LLTCs within a region, perhaps more planned approaches are needed.

Key message

This is, to our knowledge, the first work to study the effect of rapid lower level trauma center proliferation on patient outcomes. The findings of our analysis have implications for strategic planning of future trauma systems.

Predictors for Withdrawal of Life-Sustaining Therapies in Patients With Traumatic Brain Injury: A Retrospective Trauma Quality Improvement Program Database Study

Many patients with severe traumatic brain injuries (TBIs) undergo withdrawal of life-sustaining therapies (WLSTs) or transition to comfort measures, but noninjury factors that influence this decision have not been well characterized. We hypothesized that WLST would be associated with institutional and geographic noninjury factors. All patients with a head Abbreviated Injury Scale score ≥3 were identified from 2016 Trauma Quality Improvement Program data. We analyzed factors that might be associated with WLST, including procedure type, age, sex, race, insurance, Glasgow Coma Scale score, mechanism of injury, geographic region, and institutional size and teaching status. Adjusted logistic regression was performed to examine factors associated with WLST. Sixty-nine thousand fifty-three patients were identified: 66% male, 77% with isolated TBI, and 7.8% had WLST. The median age was 56 years (34-73). A positive correlation was found between increasing age and WLST. Women were less likely to undergo WLST than men (odds ratio 0.91 [0.84-0.98]) and took more time to for WLST (3 vs 2 days, P < .001). African Americans underwent WLST at a significantly lower rate (odds ratio 0.66 [0.58-0.75]). Variations were also discovered based on US region, hospital characteristics, and neurosurgical procedures. WLST in severe TBI is independently associated with noninjury factors such as sex, age, race, hospital characteristics, and geographic region. The effect of noninjury factors on these decisions is poorly understood; further study of WLST patterns can aid health care providers in decision making for patients with severe TBI.

Variation in neurosurgical intervention for severe traumatic brain injury: The challenge of measuring quality in trauma center verification

BACKGROUND

Intracranial pressure monitor (ICPm) procedure rates are a quality metric for American College of Surgeons trauma center verification. However, ICPm procedure rates may not accurately reflect the quality of care in TBI. We hypothesized that ICPm and craniotomy/craniectomy procedure rates for severe TBI vary across the United States by geography and institution.

METHODS

We identified all patients with a severe traumatic brain injury (head Abbreviated Injury Scale, ≥3) from the 2016 Trauma Quality Improvement Program data set. Patients who received surgical decompression or ICPm were identified via International Classification of Diseases codes. Hospital factors included neurosurgeon group size, geographic region, teaching status, and trauma center level. Two multiple logistic regression models were performed identifying factors associated with (1) craniotomy with or without ICPm or (2) ICPm alone. Data are presented as medians (interquartile range) and odds ratios (ORs) (95% confidence interval).

RESULTS

We identified 75,690 patients (66.4% male; age, 59 [36-77] years) with a median Injury Severity Score of 17 (11-25). Overall, 6.1% had surgical decompression, and 4.8% had ICPm placement. Logistic regression analysis showed that region of the country was significantly associated with procedure type: hospitals in the West were more likely to use ICPm (OR, 1.34 [1.20-1.50]), while Northeastern (OR, 0.80 [0.72-0.89]), Southern (OR, 0.84 [0.78-0.92]), and Western (OR, 0.88 [0.80-0.96]) hospitals were less likely to perform surgical decompression. Hospitals with small neurosurgeon groups (<3) were more likely to perform surgical intervention. Community hospitals are associated with higher odds of surgical decompression but lower odds of ICPm placement.

CONCLUSION

Both geographic differences and hospital characteristics are independent predictors for surgical intervention in severe traumatic brain injury. This suggests that nonpatient factors drive procedural decisions, indicating that ICPm rate is not an ideal quality metric for American College of Surgeons trauma center verification.

LEVEL OF EVIDENCE

Epidemiological, level III; Care management/Therapeutic level III.

Systematic review of trauma system regionalization and implementation on outcomes in traumatic brain injury patients

BACKGROUND

The number of trauma systems has increased dramatically within the United States over the past 40 years. The implementation of these systems has contributed to a decrease in mortality and improved outcomes in patients with trauma. Several studies have evaluated the effect of implementation of these systems on outcomes, but few studies examine the effects of such systems specifically on traumatic brain injury (TBI).

METHODS

A systematic review of the literature was conducted according the guidelines for the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) to determine the effects of trauma system implementation and regionalization on mortality and other outcome measures in adult TBI. We sought to include both experimental and observational studies within the United States.

RESULTS

From 1983 to 2015, nine studies were identified that adhered to the predefined inclusion and exclusion criteria representing six different geographic areas within the United States. All studies utilized a retrospective pre-post implementation methodology. A variety of mortality outcome measures were identified in the literature. Six of the nine studies demonstrated some benefit on various mortality metrics.

CONCLUSION

The existing literature on the effects of trauma system implementation or regionalization on outcomes in TBI is sparse but overall seems to convey an improvement in mortality.

Long-Term Analysis of Functional Outcomes in Traumatic Brain Injury Patients

INTRODUCTION

Traumatic brain injury (TBI) remains a significant cause of morbidity and mortality. The purpose of this study is to examine outcomes after discharge and identify factors from the index admission that may contribute to long-term mortality.

METHODS

The study population is composed of patients who survived to discharge from a previously published study examining TBI. Demographics, injury severity, and length of stay were abstracted from the index study. Phone surveys of surviving patients were performed to evaluate each patient's Glasgow Outcome Scale-Extended (GOSE). Patients who were deceased at the time of the survey were compared with those who were alive.

RESULTS

1615 patients were alive at the end of the first study period and 211 (13%) comprised the study population. Overall, the median age was 54 years, and the majority were male (74%). The median time to follow-up was 80 months. The population was severely injured, with a median injury severity score (ISS) of 25 and a median head abbreviated injury score (AIS) of 4. Overall mortality was 57%. The group that survived at the time of the survey was younger, more injured, less likely to have received beta-blockers (BB) during the index admission, and had a longer time to follow-up. After adjusting for ISS, age, base deficit, and BB, age was the only variable predictive of mortality (HR 1.03; HL 1.02-1.04).

CONCLUSION

Despite being more severely injured, younger patients were more likely to survive to follow-up. Further investigation is needed to determine if aggressive care in older TBI patients in the acute phase leads to good long-term outcomes.

Regionalization of Spine Trauma Care in an Urban Trauma System in the United States: Decreased Time to Surgery and Hospital Length of Stay

BACKGROUND

The effect of regionalized trauma care (RT) on hospital-based outcomes for traumatic spine injury (TSI) in the United States is unknown.

OBJECTIVE

To test the hypothesis that RT would be associated with earlier time to surgery and decreased length of stay (LOS).

METHODS

TSI patients >14 yr were identified using International Classification of Diseases Ninth Revision Clinical Modification diagnostic codes. Data from 2008 through 2012 were analyzed before and after RT in 2010.

RESULTS

A total of 4072 patients were identified; 1904 (47%) pre-RT and 2168 (53%) post-RT. Injury severity scores, Spine Abbreviated Injury Scale scores, and the percentage of TSIs with spinal cord injury (tSCI) were similar between time periods. Post-RT TSIs demonstrated a lower median intensive care unit (ICU) LOS (0 vs 1 d; P < 0.0001), underwent spine surgery more frequently (13% vs 11%; P = 0.01), and had a higher rate of spine surgery performed within 24 h of admission (65% vs 55%; P = 0.02). In patients with tSCI post-RT, ICU LOS was decreased (1 vs 2 d; P < 0.0001) and ventilator days were reduced (average days: 2 vs 3; P = 0.006). The post-RT time period was an independent predictor for spine surgery performed in less than 24 h for all TSIs (odds ratio [OR] 1.52, 95% confidence interval [CI]: 1.04-2.22, C-stat = 0.65). Multivariate linear regression analysis demonstrated an independent effect on reduced ICU LOS post-RT for TSIs (OR -1.68; 95% CI: -2.98 to 0.39; R2 = 0.74) and tSCIs (OR -2.42, 95% CI: -3.99-0.85; R2 = 0.72).

CONCLUSION

RT is associated with increased surgical rates, earlier time to surgery, and decreased ICU LOS for patients with TSI.

Craniectomy and Craniotomy in Traumatic Brain Injury: A Propensity-Matched Analysis of Long-Term Functional and Quality of Life Outcomes

OBJECTIVE

To report the comprehensive long-term functional and quality of life outcomes after craniectomy (CE) and craniotomy (CO) in individuals with traumatic brain injury (TBI).

METHODS

Information on all individuals with TBI who had undergone CE or CO were extracted from the TBI Model Systems database from 2002 to 2012. A 1:1 propensity matching with replacement technique was used to balance the baseline characteristics across groups. The matched sample was analyzed for outcomes during hospitalization, acute rehabilitation, and ≤2 years of follow-up.

RESULTS

We identified 1470 individuals who had undergone CE or CO. Individuals undergoing CE compared with CO demonstrated a longer length of stay in the hospital (median, 22 vs. 18 days; P < 0.0001) and acute rehabilitation (median 26 vs. 21 days; P < 0.0001). Individuals with CE had required rehospitalization more often by the 1-year follow-up point (39% vs. 25%; P < 0.0001) for reasons other than cranioplasty, including seizures (12% vs. 8%; P < 0.0001), neurologic events (i.e., hydrocephalus; 9% vs. 4%; P < 0.0001), and infections (10% vs 6%; P < 0.0001). Individuals with CE had significantly greater impairment using the Glasgow Outcome Scale-Extended, required more supervision, and were less likely to be employed at 1 and 2 years after TBI. No difference was observed in the satisfaction with life scale scores at 2 years. The Kaplan-Meier mortality estimates at 1 and 2 years showed no differences between the 2 groups (hazard ratio, 0.57; P = 0.4).

CONCLUSION

In a matched cohort, individuals undergoing CE compared with CO after TBI had a longer length of stay, decreased functional status, and more rehospitalizations. The survival at 2 years and the satisfaction with life scale scores were similar.

Level I Trauma Centers: More Is Not Necessarily Better

The optimal number of level I trauma centers (L1TCs) in a region has not been elucidated. To begin addressing this, we compared mortalities for patients treated in counties or regions with 1 L1TC to those with >1 L1TC across Ohio. Ohio Trauma Registry data from 2010 to 2012 were analyzed. Patients with age ≥15 from counties/regions with L1TC were included. Region was defined as a L1TC containing county and its neighboring counties. Two analyses were performed. In the county analysis, counties containing 1 L1TC were compared with counties with multiple L1TCs. This comparison is repeated on a regional level for the regional analysis. Subgroup analyses were performed. 38,661 and 55,064 patients were in the county and regional analysis, respectively. Patients treated in counties or regions with multiple L1TCs were significantly younger ( P < 0.001). Despite this, the mortality was similar for the two groups in the county analysis and significantly higher for regions with multiple L1TCs ( P < 0.001). Multivariate logistic regression demonstrated that having multiple L1TC coverage in a region was an independent predictor for death (odds ratios: 1.17; 1.07-1.28; P = 0.001). Subgroup analyses showed that mortality in counties and regions with multiple L1TCs was not lower in any subgroups but was higher in patients with age ≥65 and patients with blunt injuries ( P < 0.05). Having multiple L1TCs in a county was associated with increased mortality in certain patient subgroups. Having multiple L1TCs in a region was an independent predictor for death. These results should be considered carefully when designing future regionalized trauma networks. More L1TCs is not necessarily better.

Statewide Analysis Shows Collaborative Regional Trauma Network Reduces Regional Mortality

A Regional Trauma Network (RTN), composed of one level I and several lower-level trauma centers (TCs) across multiple hospital systems, was established in 2010. This collaborative network used a unified triage protocol and a single transfer center. The impact of this RTN was assessed by evaluating regional mortality changes before and after RTN establishment. Patients in the state trauma registry aged 15 and older from 2006 to 2012 were analyzed; 2006 to 2009 and 2010 to 2012 were designated as pre-RTN and RTN periods, respectively. The region was defined as a county containing L1TC and its adjacent counties. Any counties bordering multiple L1TC-containing counties were excluded from analysis. Mortality was compared for all regions before and after RTN implementation. The following subgroups were also included a priori for the comparison: Injury Severity Score ≥15, age ≥65, and trauma mechanisms. 121,448 patients were analyzed; 66,977 and 54,471 patients were in the pre-RTN and RTN groups, respectively. Mean age was 58; 90 per cent had blunt injuries. The overall mortality was 4.9 per cent. Mortality comparisons over time for all regions are presented. The RTN region was the only region in the state that had mortality reduction in all patient subgroups. After adjusting for age, Injury Severity Score, level of TC that performed treatment, and trauma mechanism, RTN implementation was an independent predictor of survival (odds ratio: 0.876; 95% CI: 0.771–0.995, P = 0.04, c-statistic: 0.84). These findings suggest that regional collaboration and network-wide, uniform triage practices should be key components in the development of regionalized trauma networks.

Polytrauma patients in the Netherlands and the USA: A bi-institutional comparison of processes and outcomes of care

BACKGROUND

Modern trauma systems differ worldwide, possibly leading to disparities in outcomes. We aim to compare characteristics and outcomes of blunt polytrauma patients admitted to two Level 1 Trauma Centers in the US (USTC) and the Netherlands (NTC).

METHODS

For this retrospective study the records of 1367 adult blunt trauma patients with an Injury Severity Score (ISS) ≥ 16 admitted between July 1, 2011 and December 31, 2013 (640 from NTC, 727 from USTC) were analysed.

RESULTS

The USTC group had a higher Charlson Comorbidity Index (mean [standard deviation] 1.15 [2.2] vs. 1.73 [2.8], p<0.0001) and Injury Severity Score (median [interquartile range, IQR] 25 [17-29] vs. 21 [17-26], p<0.0001). The in-hospital mortality was similar in both centers (11% in USTC vs. 10% NTC), also after correction for baseline differences in patient population in a multivariable analysis (adjusted odds ratio 0.95, 95% confidence interval 0.61-1.48, p=0.83). USTC patients had a longer Intensive Care Unit stay (median [IQR] 4 [2-11] vs. 2 [2-7] days, p=0.006) but had a shorter hospital stay (median [IQR] 6 [3-13] vs. 8 [4-16] days, p<0.0001). USTC patients were discharged more often to a rehabilitation center (47% vs 10%) and less often to home (46% vs. 66%, p<0.0001), and had a higher readmission rate (8% vs. 4%, p=0.01).

CONCLUSION

Although several outcome parameters differ in two urban area trauma centers in the USA and the Netherlands, the quality of care for trauma patients, measured as survival, is equal. Other outcomes varied between both trauma centers, suggesting that differences in local policies and processes do influence the care system, but not so much the quality of care as reflected by survival.

Prehospital Assessment of Trauma

The organization of prehospital care for trauma patients began in the military arena. At the urging of multiple stakeholders and providers, these lessons were applied to the civilian setting and emergency medical services were created across the nation. Advances have taken place in the triage, transport, and management of severely injured patients. Many issues remain in the care of trauma patients in the prehospital environment. Collaboration between stakeholders and providers, regionalization of trauma care, and protocol-driven care may be solutions to some of these issues. Further research is necessary to dictate standard of care in this early phase after injury.

Performance of a regional trauma network: A state-wide analysis

BACKGROUND

The Northern Ohio Trauma System (NOTS), established in 2010, is a collaborative regional trauma system composed of one level I and several lower-level trauma centers (TCs) across multiple hospital systems. Mortalities between counties in NOTS and other Ohio counties were compared to assess NOTS performance.

METHODS

State trauma registry was analyzed for patients 15 years or older from 2006 to 2012. Mortality change over time was assessed by comparing all counties before and after NOTS establishment. Two analyses were done in the post-NOTS period: (1) a county analysis, comparing Cuyahoga County, the county containing NOTS level I TC (L1TC), with other counties containing L1TCs and (2) a regional analysis, comparing Cuyahoga and its adjacent counties (i.e., the NOTS region) with other L1TC containing regions. The following subgroups were included a priori: Injury Severity Score 15 or greater, age 65 years or older, and trauma mechanism.

RESULTS

A total of 178,143 patients were analyzed. Cuyahoga was the only county that had a decrease in mortality for both the overall group and all subgroups over time (all p < 0.05). Both the county and regional analyses showed that the overall NOTS patients were 1 to 4 years older (p < 0.05), had similar or higher Injury Severity Score (p < 0.05), and were treated more often at lower-level TCs (p < 0.001). County analysis demonstrated that Cuyahoga County had approximately 1% lower mortality in geriatrics patients compared with non-NOTS counties. Regional analysis showed lower mortality in the NOTS region for the overall patient group, as well as geriatric and blunt injuries subgroups.

CONCLUSIONS

Cuyahoga was the only county in Ohio that had significant mortality reduction for all patient groups over time. Trauma system regionalization was associated with greater utilization of lower-level TCs and lower patient mortality. These findings suggest that a collaborative regional trauma system may be more important than the number of L1TC in an area.

LEVEL OF EVIDENCE

Therapeutic/care management study, level IV.

Despite Trauma Center Closures, Trauma System Regionalization Reduces Mortality and Time to Definitive Care in Severely Injured Patients

The Northern Ohio Trauma System (NOTS), consisting of multiple hospital systems, was established in 2010 to improve trauma outcomes. This study assessed its impact on mortality and time to definitive care, focusing especially on the severely injured patients. NOTS trauma registry was queried for all trauma activations from 2008 to 2013. The years between 2008–2009 and 2011–2013 were designated as pre- and post-NOTS, respectively. Data from 2010 was excluded as a transitional year. Two trauma centers (TCs) closed in 2010. Predetermined patient subgroups were analyzed. A total of 27,843 patients were examined. Mean age was 46 and 64 per cent were male. Median Injury Severity Score (ISS) was five, and 87 per cent sustained blunt injuries. Of these, 10,641 patients were pre-NOTS and 17,202 were post-NOTS. Comparing the two groups, mortality decreased from 5 to 4 per cent post-NOTS (P < 0.001); median time to definitive care increased by 12 minutes post-NOTS. Multivariate logistic regression showed that NOTS implementation was an independent predictor for survival (P = 0.008), whereas time to definitive care was not. Subgroup analyses demonstrated mortality reductions post-NOTS for all subgroups except patients with penetrating injuries, where mortality remained the same despite an increase in ISS. Patients with ISS ≥15 had a 23 per cent relative reduction in mortality, and their median time to definitive care decreased by 12 minutes. Implementation of a collaborative, regional trauma system was associated with mortality reduction and shortened time to definitive care in the severely injured patients. These findings highlight the importance of collaboration in the future development of regional trauma systems.

The impact of physical therapy in patients with severe traumatic brain injury during acute and post-acute rehabilitation according to coma duration

[Purpose] The aim of study was to evaluate the impact of physical therapy on the recovery of motor and mental status in patients who sustained a severe traumatic brain injury, according to coma duration in acute and post-acute rehabilitation. [Subjects and Methods] The study population comprised patients with levels of consciousness ranging from 3 to 8 according to Glasgow Coma Scale score. The patients were divided into 2 groups based on coma duration as follows: group 1, those who were in a coma up to 1 week, and group 2, those who were in a coma for more than 2 weeks. The recovery of the patients' motor function was evaluated according to the Motor Assessment Scale and the recovery of mental status according to the Mini-Mental State Examination. [Results] The evaluation of motor and mental status recovery revealed that the patients who were in a coma up to 1 week recovered significantly better after physical therapy during the acute rehabilitation than those who were in a coma for longer than 2 weeks. [Conclusion] The recovery of motor and mental status of the patients in acute rehabilitation was significantly better for those in a coma for a shorter period.