Triaging patients with serious head injury: results of a simulation evaluating strategies to bypass hospitals without neurosurgical facilities

The Head Injury Transportation Straight to Neurosurgery (HITS-NS) randomised trial: a feasibility study

BACKGROUND

Reconfiguration of trauma services, with direct transport of traumatic brain injury (TBI) patients to neuroscience centres (NCs), bypassing non-specialist acute hospitals (NSAHs), could potentially improve outcomes. However, delays in stabilisation of airway, breathing and circulation (ABC) and the difficulties in reliably identifying TBI at scene may make this practice deleterious compared with selective secondary transfer from nearest NSAH to NC. National Institute for Health and Care Excellence guidance and systematic reviews suggested equipoise and poor-quality evidence - with regard to 'early neurosurgery' in this cohort - which we sought to address.

METHODS

Pilot cluster randomised controlled trial of bypass to NC conducted in two ambulance services with the ambulance station (n = 74) as unit of cluster [Lancashire/Cumbria in the North West Ambulance Service (NWAS) and the North East Ambulance Service (NEAS)]. Adult patients with signs of isolated TBI [Glasgow Coma Scale (GCS) score of < 13 in NWAS, GCS score of < 14 in NEAS] and stable ABC, injured nearest to a NSAH were transported either to that hospital (control clusters) or bypassed to the nearest NC (intervention clusters).

PRIMARY OUTCOMES

recruitment rate, protocol compliance, selection bias as a result of non-compliance, accuracy of paramedic TBI identification (overtriage of study inclusion criteria) and pathway acceptability to patients, families and staff. 'Open-label' secondary outcomes: 30-day mortality, 6-month Extended Glasgow Outcome Scale (GOSE) and European Quality of Life-5 Dimensions.

RESULTS

Overall, 56 clusters recruited 293 (169 intervention, 124 control) patients in 12 months, demonstrating cluster randomised pre-hospital trials as viable for heath service evaluations. Overall compliance was 62%, but 90% was achieved in the control arm and when face-to-face paramedic training was possible. Non-compliance appeared to be driven by proximity of the nearest hospital and perceptions of injury severity and so occurred more frequently in the intervention arm, in which the perceived time to the NC was greater and severity of injury was lower. Fewer than 25% of recruited patients had TBI on computed tomography scan (n = 70), with 7% (n = 20) requiring neurosurgery (craniotomy, craniectomy or intracranial pressure monitoring) but a further 18 requiring admission to an intensive care unit. An intention-to-treat analysis revealed the two trial arms to be equivalent in terms of age, GCS and severity of injury. No significant 30-day mortality differences were found (8.8% vs. 9.1/%; p > 0.05) in the 273 (159/113) patients with data available. There were no apparent differences in staff and patient preferences for either pathway, with satisfaction high with both. Very low responses to invitations to consent for follow-up in the large number of mild head injury-enrolled patients meant that only 20% of patients had 6-month outcomes. The trial-based economic evaluation could not focus on early neurosurgery because of these low numbers but instead investigated the comparative cost-effectiveness of bypass compared with selective secondary transfer for eligible patients at the scene of injury.

CONCLUSIONS

Current NHS England practice of bypassing patients with suspected TBI to neuroscience centres gives overtriage ratios of 13 : 1 for neurosurgery and 4 : 1 for TBI. This important finding makes studying the impact of bypass to facilitate early neurosurgery not plausible using this study design. Future research should explore an efficient comparative effectiveness design for evaluating 'early neurosurgery through bypass' and address the challenge of reliable TBI diagnosis at the scene of injury.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN68087745.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 20, No. 1. See the NIHR Journals Library website for further project information.

Is Overtriage Associated With Increased Mortality? Insights From a Simulation Model of Mass Casualty Trauma Care

Purpose: To examine the relationship between overtriage and critical mortality after a mass casualty incident (MCI) using a simulation model of trauma system response.

Methods: We created a discrete event simulation model of trauma system management of MCIs involving individual patient triage and treatment. Model variables include triage performance, treatment capability, treatment time, and time-dependent mortality of critically injured patients. We model triage as a variable selection process applied to a hypothetical population of critically and noncritically injured patients. Treatment capability is represented by staffed emergency department trauma bays with associated staffed operating rooms that are recycled after each use. We estimated critical and noncritical patient treatment times and time-dependent mortality rates from the trauma literature.

Results: In this simulation model, overtriage, the proportion of noncritical patients among all of those labeled as critical, has a positive, negative, or variable association with critical mortality depending on its etiology (ie, related to changes in triage sensitivity or to changes in the prevalence and total number of critical patients). In all of the modeled scenarios, the ratio of critical patients to treatment capability has a greater impact on critical mortality than overtriage level or time-dependent mortality assumption.

Conclusions: Increasing overtriage may have positive, negative, or mixed effects on critical mortality in this trauma system simulation model. These results, which contrast with prior analyses describing a positive linear relationship between overtriage and mortality, highlight the need for alternative metrics to describe trauma system response after MCIs. We explore using the relative number of critical patients to available and staffed treatment units, or the critical surge to capability ratio, which exhibits a consistent and nonlinear association with critical mortality in this model. (Disaster Med Public Health Preparedness. 2007;1(Suppl 1):S14–S24)

Effective management of severe traumatic brain injury in a district hospital

The authors investigated how effectively adults with severe traumatic brain injury (TBI) can be managed in a district general hospital intensive care unit offering intracranial pressure monitoring (ICPM) receiving advice from a neurosurgical unit. A single-centre case series with retrospective review of prospectively collected information was undertaken of 44 consecutive patients presenting over seven years from January 2003 to January 2010 with severe traumatic brain injury to a single district general hospital intensive care unit serving a population of 500,000 adults. A prospectively entered clinical database was used to obtain information including patient demographics, Glasgow Coma Score (GCS) on admission, ICPM insertion, ICPM-related complications, inpatient mortality and neurosurgical advice. Case notes were used to ratify information and obtain neurorehabilitation clinic functional outcome scores. Forty-four patients were identified (40 male, age range 16-77 years). Mortality in intensive care was 30%. Twenty-eight patients received frontal twist drill ICPM following neurosurgical advice. ICPM had 2 (7%) device malfunctions but no other complications. Twelve additional patients were transferred to tertiary centres. Patients (23 of 31) who survived ICU stay (74%) were referred to neurorehabilitation. Mean clinic follow-up was 14 months. All patients had a Glasgow Outcome Score (GOS) of 3 or 4 at initial clinic assessment. Twenty-two improved to GOS to 4 or 5 at clinic discharge. One patient died prior to clinic discharge. Carefully selected patients with severe TBI can be managed safely and effectively in a district general hospital offering ICPM insertion if transfer to a neurosurgical centre is not possible. Neurosurgical advice regarding patient selection and on-going management is fundamental to provide a good service. Protocol driven therapies provide a useful systematic approach to doctors who do not deal with severe TBI on a routine basis.

Impact of cervical spine management brain injury on functional survival outcomes in comatose, blunt trauma patients with extremity movement and negative cervical spine CT: application of the Monte Carlo simulation

Cervical spine (CS) magnetic resonance imaging (MRI) and collar use may prevent quadriplegia, yet create brain injury. We developed a computer model to assess the effect of CS management strategies on outcomes in comatose, blunt trauma patients with extremity movement and a negative CS CT scan. Strategies include early collar removal (ECR), ECR & MRI, late collar removal (LCR), and LCR & MRI. MRI risks include hypoxia, hypotension, increased intracranial pressure (↑ICP), and ventilator-associated pneumonia (VAP). LCR risks include ↑ICP, VAP, and delirium. Model elements include Quadriplegia and Primary, Secondary, LCR, and MRI Brain Injury. The Monte Carlo simulation determines health outcomes (Functional Survival versus Quadriplegia, Severe Brain Disability, or Dead). Utility values are Functional Survival 0.90, Quadriplegia 0.20, Severe Brain Disability 0.10, and Dead 0.00. Years of life expectancy are Functional Survival 39.5, Quadriplegia 20.0, Severe Brain Disability 20.0, and Dead 0.0. Unstable CS rate 2.5%: Functional Survival/1,000: Unstable Patients: ECR 384, LCR 350, LCR & MRI 332, ECR & MRI 331; High-Risk Patients: ECR 161, LCR 151, LCR & MRI 140, ECR & MRI 153; Stable Patients: ECR 596, LCR 587, LCR & MRI 573, ECR & MRI 595. Quality-Adjusted Life Months for Unstable, High-Risk, and Stable Patients are greater with ECR; Stable Patient ECR and ECR & MRI are similar. Unstable CS rate 0.5%: Functional Survival/1000: Unstable Patients: ECR 394, LCR 352, LCR & MRI 332, ECR & MRI 332; High-Risk Patients: ECR 164, LCR 151, LCR & MRI 140, ECR & MRI 152; Stable Patients: ECR 611, LCR 592, LCR & MRI 576, ECR & MRI 598. Quality-Adjusted Life Months for Unstable, High-Risk, and Stable Patients are greater with ECR. LCR and MRI brain injury results in losses of functional survivorship that exceed those from quadriplegia. Model results suggest that early collar removal without cervical spine MRI is a reasonable, and likely the preferable, cervical spine management strategy for comatose, blunt trauma patients with extremity movement and a negative cervical spine CT scan.

Quand faut-il décider d'un transfert en milieu neurochirurgical spécialisé?

The annual incidence of severe head injury lies between 9 and 25/100000 inhabitants, depending on the criteria used for its definition. In most countries, the shortage in neurosurgical ICU beds makes it impossible to take in charge all patients with a severe brain injury. But the beneficial effect of a specialized neurosurgical ICU on outcome after brain injury has been demonstrated in several retrospective studies. Ideally, the best strategy is to admit the patients with a severe head injury directly in a neurosurgical centre. When this is not possible, the appropriate decision of a secondary transfer relies on the quality of the relationships between physicians in the community and the neurosurgical hospitals. Teleradiology is the best method to avoid unnecessary transportation or deleterious delays before transfer. In an era of decreasing medical budgets, technical improvements to enhance medical cooperation should be encouraged.

The effects of ambulance diversion: a comprehensive review

OBJECTIVES

To review the current literature on the effects of ambulance diversion (AD).

METHODS

The authors performed a systematic review of AD and its effects. PubMed, EMBASE, the Cochrane database, societal meeting abstracts, and references from relevant articles were searched. All articles were screened for relevance to AD.

RESULTS

The authors examined 600 citations and reviewed the 107 articles relevant to AD. AD is a common occurrence that is increasing in frequency. AD is associated with periods of emergency department (ED) crowding (Mondays, mid-afternoon to early evening, influenza season, and when hospitals are at capacity). Interventions that redesign the AD process or that provide additional hospital or ED resources reduce diversion frequency. AD is associated with increased patient transport times and time to thrombolytics but not with mortality. AD is associated with loss of estimated hospital revenues. Short of anecdotal or case reports, no studies measured the effect of AD on ED crowding, morbidity, patient and provider satisfaction, or EMS resource utilization.

CONCLUSIONS

Despite its common use, there is a relative paucity of studies on the effects of AD. Further research into these effects should be performed so that we may understand the role of AD in the health system.