- Original research
- Open Access
Coma of unknown origin in the emergency department: implementation of an in-house management routine
- Mischa Braun†1, 2,
- Wolf Ulrich Schmidt†1, 2Email author,
- Martin Möckel3,
- Michael Römer4,
- Christoph J. Ploner1 and
- Tobias Lindner3
© Braun et al. 2016
Received: 21 November 2015
Accepted: 20 April 2016
Published: 27 April 2016
Coma of unknown origin is an emergency caused by a variety of possibly life-threatening pathologies. Although lethality is high, there are currently no generally accepted management guidelines.
We implemented a new interdisciplinary standard operating procedure (SOP) for patients presenting with non-traumatic coma of unknown origin. It includes a new in-house triage process, a new alert call, a new composition of the clinical response team and a new management algorithm (altogether termed “coma alarm”). It is triggered by two simple criteria to be checked with out-of-hospital emergency response teams before the patient arrives. A neurologist in collaboration with an internal specialist leads the in-hospital team. Collaboration with anaesthesiology, trauma surgery and neurosurgery is organised along structured pathways that include standardised laboratory tests and imaging. Patients were prospectively enrolled. We calculated response times as well as sensitivity and false positive rates, thus proportions of over- and undertriaged patients, as quality measures for the implementation in the SOP.
During 24 months after implementation, we identified 325 eligible patients. Sensitivity was 60 % initially (months 1–4), then fluctuated between 84 and 94 % (months 5–24). Overtriage never exceeded 15 % and undertriage could be kept low at a maximum of 11 % after a learning period. We achieved a median door-to-CT time of 20 minutes. 85 % of patients needed subsequent ICU treatment, 40 % of which required specialised neuro-ICUs.
Our results indicate that our new simple in-house triage criteria may be sufficient to identify eligible patients before arrival. We aimed at ensuring the fastest possible proceedings given high portions of underlying time-sensitive neurological and medical pathologies while using all available resources as purposefully as possible.
Our SOP may provide an appropriate tool for efficient management of patients with non-traumatic coma. Our results justify the assignment of the initial diagnostic workup to neurologists and internal specialists in collaboration with anaesthesiologists.
Disorders of consciousness including coma in non-traumatic patients can be caused by a wide variety of pathologies affecting the central nervous system (CNS) including potentially life-threatening and highly time-sensitive medical, neurological or neurosurgical emergencies . They are a frequent challenge in emergency medicine: 5–9 % of all patients in emergency departments present with acute non-traumatic disorders of consciousness and up to 2 % are reported to be comatose on admission [2–4]. Moreover, they are associated with a very high in-hospital mortalitiy of 25–48 % in western populations [5, 6]. Underlying pathologies have been classified into primary or focal damage to the CNS and secondary affection of the CNS resulting in a diffuse brain dysfunction, such as in metabolic derangement or intoxication . The reported prevalence of structural vs. metabolic coma varies from 28 to 64 and 37 to 75 %, respectively . Presumptive diagnoses need to be confirmed or excluded promptly in order to treat the patient as quickly as possible or to move on to the next diagnostic step. In many cases, a good outcome critically depends on early treatment (“time is brain”), e.g. in meningo-encephalitis  or basilar artery occlusion . In order to do this in a minimum of time, a standardised inter-professional and interdisciplinary algorithm is of utmost importance . Such an algorithm should include an evidence-based cascade of diagnostic procedures and involve only those medical specialties that are definitely required for the evaluation and management of disorders of consciousness. This is a matter of particular interest especially in countries where a board-certification for in-hospital emergency physicians does not (yet) exist and where initial management of comatose patients in emergency departments (EDs) is frequently carried out by anaesthesiologists, internal specialists or surgeons, even in cases of focal CNS-pathologies such as intracerebral haemorrhage, meningo-encephalitis or basilar artery occlusion.
In Germany, on-site management of patients with disorders of consciousness is carried out by paramedics and trained emergency physicians. In order to assure a smooth and rapid workflow, out-of-hospital teams announce their patients in advance to the ED and state the leading emergency symptom. Based on this information, ED staff may trigger an appropriate in-house alarm before the estimated time of the patient’s arrival. This essentially involves a simultaneous alert call to a standardised group of recipients. The aim of such an alarm routine is to minimise delays and to ensure a direct contact between out-of-hospital teams and in-hospital physicians. Our university hospital campus (Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum) cares for approximately 100.000 emergency patients per year . However, this number does not include patients who are comatose due to an obvious reason, such as an evident cardio-respiratory arrest, and thus admitted directly to specialised internal medicine intensive care units (ICUs). In past years, adult patients presenting to our ED with non-traumatic disorders of consciousness of unknown origin used to be treated along a well-established shock trauma centre protocol (level I trauma centre) that requires a team of trauma surgeons, anaesthesiologists and radiologists as well as a neurosurgeon in the first line. If, after initial assessment based on Advanced Trauma Life Support (ATLS®) , there had not been any clinical evidence for a traumatic reason explaining the patient’s state, the patient would then be moved on to CT scanning. Only after CT scans had excluded signs of traumatic brain injury (TBI) or intracranial haemorrhage, other medical specialties would have been involved. However, since secondary (e.g. metabolic, hypoxic etc.) causes of brain dysfunction account for a high percentage of underlying pathologies that is similar to the percentage of patients suffering from focal lesions of the CNS , this practice frequently caused delays in diagnosis and treatment of both medical and non-haemorrhagic neurological conditions.
To improve the management of adult non-traumatic patients presenting with a disorder of consciousness or coma in our hospital, an interdisciplinary expert panel developed a new in-house standard operating procedure (SOP) that includes a new in-house triage process, a new alert call, a new composition of the clinical response team and a new management algorithm (altogether termed “coma alarm”). The main goal of this feasibility study was to evaluate the success of the implementation of the SOP into a working ED environment including the sensitivity of the in-house triage process during a period of 24 months following its introduction in May 2013.
Number of staff required for the in-house initial response teams; new coma alarm compared to well-established multiple trauma alarm
Multiple trauma alarm
3 Trauma surgeons
Neurosurgeon (notification only)
2 Anaesthesiology nurses
2 Anaesthesiology nurses
3 ED nurses
3 ED nurses
An ethics vote for the analysis of routinely acquired clinical data was obtained from the Ethics Commission of the Charité-Universitätsmedizin Berlin (“Emergency Processes in Clinical Structures”, EA1/172/14). All coma alarms between May 2013 and April 2015 were identified retrospectively in our hospital’s electronic patient database. We analysed all available documentation of each respective patient and determined a) whether the patient was in a state of reduced consciousness when contacted by paramedics or emergency physicians on-site, b) whether the patient had a disorder of consciousness on admission to the ED as determined by the team-leading neurologist and c) if there was any evidence of multiple trauma including primary TBI. Patients who had either been documented to be fully awake at all times (no persistent or transient loss of consciousness) or who presented with evidence of multiple trauma were defined as overtriaged or “false alarms”. All emergency referrals with a diagnosis already known were classified likewise as there was no need for further diagnostic procedures. Besides, we analysed all other emergency patients seen by a neurologist in the ED between May 2013 and April 2015 and applied the criteria mentioned above in order to identify undertriaged patients or “misses”.
Characteristics and outcomes for patients evaluated in this study (n = 325)
With abnormality on CT scan
Admitted to ICU
Among the 277 patients correctly triaged for the coma alarm management routine (“hits”), 266 patients received CT scans of head and, if necessary, thorax and abdomen after an average door-to-CT time of 20 min (median; interquartile range 16–27 min) covering handover of the patient, stabilization of vital parameters, clinical examination and nursing tasks in the emergency room (see Fig. 1). 11 patients were not CT-scanned but received emergency MR scans instead (2 cases) or deceased in the resuscitation room (1 case) or presented with unmistakable evidence of either asphyxiation or intoxication and were not scanned in time due to psychomotor agitation (8 cases).
For patients with multiple trauma, clinical pathways and structured education concepts such as ATLS® are well established in most EDs. Implementation of clinical algorithms is feasible [15, 16], shortens the time to diagnosis and treatment, and has been shown to significantly improve patient outcome [17, 18]. Similarly, in common medical and neurological emergencies such as myocardial infarction  and stroke , clinical pathways and implemented algorithms accelerate clinical workflow and improve outcome [21, 22]. Surprisingly, at least to our knowledge, comparable pathways for disorders of consciousness have not yet been universally implemented.
Here, we established a new ED management routine specifically designed for patients with the leading symptom of a non-traumatic disorder of consciousness of unknown origin. The regular admission of these patients to our ED justified the need for a specialised management that particularly focuses on rapid identification and treatment of possibly life-threatening underlying disorders. The new SOP thus includes an in-house alarm call triggered by the information on the patient’s state of consciousness given by out-of-hospital emergency services. By adhering to the new simple in-house triage criteria eligible patients could be properly identified in up to 94 % of the cases after an initial learning period.
We deliberately chose not to set a specific GCS criterion to identify eligible patients for the protocol because of the GCS’s unsatisfactory inter-rater reliability  and its insufficiency in correctly assessing the level of consciousness in patients with focal and/or lateralized neurological symptoms. A neurologist, an internal specialist, an anaesthesiology team, three ED nurses, two radiographers and a backup trauma surgeon are prompted to the ED. These staff and equipment requirements are comparable to resources required for management of multiple trauma patients in the ED . We decided on the neurologist to lead the emergency team, coordinate the diagnostic steps, collect the patient’s past medical history, if available, and define the most likely diagnosis. This is done in close collaboration with the other members of the team, given that non-traumatic disorders of consciousness can be caused by either primary brain disease or secondary diffuse neuronal dysfunction . In multiple trauma management, it is still a matter of debate whether there should be a single team leader or a team-guided approach . However, the need for structured guidance and supervision of the process is beyond any dispute . Although we did not systematically evaluate different team structures, we deem appropriate our hybrid approach that includes team-guidance by a neurologist and obligatory interdisciplinary team-time-outs for a highly interdisciplinary emergency like coma and other disorders of consciousness of unknown origin.
One of the main advantages of our protocol is gathering all required personnel on site before the patient arrives in order to ensure the fastest possible proceedings in time-sensitive cases. However, the protocol was deliberately designed to give the opportunity to reduce the level of resource allocation whenever incoming diagnostic results justifies to do so (e.g. 26 overtriaged patients were excluded from the cohort of eligible patients; CSF testing was not performed if preceding investigations provided positive and unequivocal results; etc.). Thus, team-time-outs play an important role not only for interdisciplinary consultation but they also allow for the level of resource allocation to be adjusted to any required level.
Given the high percentage of patients requiring intensive care management after admission, there is a need to use available resources as purposefully as possible. Furthermore, the high portion of life-threatening causes of coma and other disorders of consciousness of non-traumatic origin is reflected in the scope of diagnoses in combination with the remarkable percentage of patients who deceased in the immediate course following presentation to ED (Table 2). This is the strongest argument for a multi-disciplinary approach with an emphasis on primarily neurological and medical first-line assessment as opposed to a primary surgical management which is in fact mostly required to treat collateral problems (such as superficial wounds) without impact on the underlying pathologies in this cohort of patients.
Over 85 % of all eligible patients required intensive care treatment, over 40 % of which needed specialised neuro-intensive care or neurosurgical treatment following admission due to primary disorders of the CNS. A similar portion was treated in ICUs specialised in internal medicine. This is another argument for assigning the initial diagnostic workup to neurologists and internal specialists rather than to surgeons, with anaesthesiologists focusing on life support. Initial management does usually not require the immediate presence of a neurosurgeon, as initial neurological and neurosurgical evaluation of comatose patients do not differ. Nevertheless, whenever required (e.g. CT reveals subdural haematoma), our SOP allows for prompting the already pre-alerted neurosurgeon on call to the ED as quickly as possible.
The absolute number of eligible patients included in this study showed an upward trend over time, possibly indicating that establishing the SOP may have met a certain demand in our catchment area for a specialised emergency management for patients presenting with a disorder of consciousness without an obvious origin. Although the information provided by out-of-hospital emergency teams frequently was fragmentary, there was a surprisingly high sensitivity of the in-house triage process required to identify patients eligible for the SOP after the first four months. Hence it appears that the obligatory two questions to be asked by the head nurse communicating with out-of-hospital response teams may be sufficient to correctly identify the patients that our SOP is intended for. Overtriage was only 8.6 % and was tolerated throughout as “false alarms” may indeed result in a strain of hospital resources but do not put patients to any risk. Furthermore, our rate is lower than in other reports of newly implemented alarm routines, e.g. in trauma management . After an initial learning period of 8 months, undertriage could be kept at an overall low rate of 9.5 %. The aim is to reduce this figure even further by continuous training of all personnel involved. We determined each respective patient’s door-to-CT time as a reliable marker of time efficiency of our newly established management routine. By a median time of 20 min we could achieve a shorter time than reported in other routines for multiple trauma [17, 28] or stroke . However, a complete evaluation of this marker is limited since comparable data from eligible patients was not prospectively collected before the implementation of our new SOP.
The successful implementation of an alarm-triggered management routine specifically designed for patients presenting with disorders of consciousness of unknown origin provides us with a powerful tool to optimise diagnostic work-up and treatment. Furthermore, the alarm-tagged cases will allow for systematic investigation of this fundamental emergency symptom in further detail. After proof of feasibility in this study, subsequent interventional studies based on a growing registry of clinical data will aim at evaluating the effects on outcomes, scrutinising the validity and priority of different diagnostic tools and ultimately establishing an evidence-based SOP “from street to ICU” for disorders of consciousness of unknown origin which is currently lacking in emergency medicine.
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