Transient loss of consciousness (T-LOC) is defined as ‘spontaneous loss of consciousness with complete recovery after the event’ (NICE 2014). T-LOC occurs due to global cerebral hypoperfusion and is a common pre-hospital presentation.
T-LOC is an umbrella term that encompasses many conditions:
|Potential causes||90% of T-LOC cases|
|Uncomplicated faint||Situational syncope|
|Other neurally mediated conditions e.g. stroke||Vasovagal syncope|
|Structural cardiac conditions||Psychogenic non-epileptic seizures|
(Reuber et al, 2016)
T-LOC is the symptom. The underlying mechanism and pathophysiology may vary but the assessment and management of these patients should be standardised.
Detailed history taking must be emphasised. A detailed history will aid in diagnosis and help to identify ‘red flags’. Corroborative history from witnesses and family is imperative (Fulde 2014). These questions are of greater importance in those patients who crews might consider ANR appropriate. These should be clearly documented and assessed for.
A standard and full set of clinical observations should be undertaken. This should also encompass standing/sitting blood pressures and auscultation of heart sounds (if in scope of practice).
Orthostatic hypotension is a cause of T-LOC. The patient should be seated for 5 minutes and then stand for 3 minutes. Blood pressure is measured just prior to standing and at 1 minute and 3 minutes of standing. A sustained fall of systolic blood pressure of at least 20mmHg or diastolic blood pressure of 10mmHg within 3 minutes of standing is diagnostic of orthostatic hypotension (Gibbons et al 2017).
The purpose of auscultation is to identify the presence or absence of a heart murmur. The presence of a murmur may suggest a valvular abnormality (Kumar & Clark 2009). A murmur in conjunction with an episode of T-LOC is a red flag that warrants further investigation. For those patients that refuse hospital transport it provides additional clinical information to be documented.
All patients who have experienced a T-LOC must undergo a 12-Lead ECG. The following pathologies should be assessed for:
|W||Wolff-Parkinson White||P, PR|
|O||Obstructed AV pathway||PR|
|L||Left ventricular hypertrophy (consider Aortic Stenosis or Hypertrophic Obstructive Cardiomyopathy (HOCM))||QRST|
|R||Repolarisation abnormality (long QT, short QT)||QT|
The presence of one or more of the following ‘red flags’ in conjunction with a T-LOC should warrant hospital transport:
Situational syncope can be diagnosed when there are no features from the clinical assessment that suggest an alternative diagnosis AND the syncope is clearly provoked by straining during micturition, coughing or swallowing.
Uncomplicated faint (vasovagal syncope) can be diagnosed when there are no features from the clinical assessment that suggest an alternative diagnosis AND there are features suggestive of uncomplicated faint. Consider the three Ps:
*the existence of prodromal symptoms is more frequently associated with benign causes
A diagnosis of situational syncope or uncomplicated faint requires competence in ECG interpretation. If in doubt or if any ‘red flags’ have been identified the patient should be transported to hospital for further investigation.
Assaf, S., & Libby, C. (2017). Asymptomatic Wolff-Parkinson-White Syndrome (WPW). Journal ofEducation and Teaching in Emergency Medicine, 2(3).
Brugada, R., Campuzano, O., Brugada, G., Brugada, P., Brugada, J. & Hong, K. (2005) Brugada Syndrome Synonym: Sudden Unexpected Nocturnal Death Syndrome. GeneReviews
Fulde, G. & Fulde, S. (2014) Emergency Medicine: the principles of practice. (6th ed). Elsevier Australia
Gibbons, C. H., Schmidt, P., Biaggioni, I., Frazier-Mills, C., Freeman, R., Isaacson, S. & Mehdirad, A. (2017). The recommendations of a consensus panel for the screening, diagnosis, and treatment of neurogenic orthostatic hypotension and associated supine hypertension. Journal of neurology, 264, 1567-1582.
Kumar, P. & Clark, M. (2009) Kumar & Clark’s Clinical Medicine. (7th ed). Saunders Elsevier
National Institute of Clinical Excellence (2014) Transient loss of consciousness (‘blackouts’) in over 16s. London: NICE.
Reuber, M., Chen, M., Jamnadas-Khoda, J., Broadhurst, M., Wall, M., Grünewald, R. A. & Walker, M. (2016). Value of patient-reported symptoms in the diagnosis of transient loss of consciousness, 625-633.87, Neurology.
Huszar’s Basic Dysrhythmias and Acute Coronary Syndromes: Interpretation andWesley, K. (2011) Management. (4th ed). Elsevier Mosby JEMS.
Matt Campbell, AP24017
Ambulance Paramedic, Metropolitan Ambulance Service