A short cut review was carried out to establish whether patients presenting to the emergency department after a near drowning should have a CT head scan as part of their initial assessment. A search of the literature found only three studies directly relevant to the question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of these papers are tabulated. The clinical bottom line is that anyone with GCS≤4 should have a CT head as an abnormal scan at this stage heralds a very poor prognosis.
- emergency care systems
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Three part question
In [patients who have nearly drowned] does [a CT scan of the head] provide [useful diagnostic or prognostic information]?
A 21-year-old man presents to the emergency department after falling into a river. He was rescued and resuscitated at the scene but now has a Glasgow Coma Scale (GCS) of 7. There is no evidence of trauma other than the immersion in water. You wonder if a CT scan of his head will aid his management.
Medline 1946 to September Week 1 2019 and Embase 1980 to week 38 2019 using the OVID interface.
Medline: [exp Near Drowning/ OR exp Drowning/ OR drowning.mp. OR drown$.mp. OR exp Immersion/ OR immersion.mp. OR immer$.mp. OR submersion.mp. OR submer$.mp.] AND [ exp Tomography, X-Ray Computed/ OR CT Head.mp. OR CT brain.mp. OR brain imaging.mp. or exp Neuroimaging/] LIMIT to human AND English Language.
Embase: [exp Near Drowning/ OR exp Drowning/ OR drowning.mp. OR drown$.mp. OR exp Immersion/ OR immersion.mp. OR immer$.mp. OR submersion.mp. OR submer$.mp.] AND [ exp Tomography, X-Ray Computed/ OR CT Head.mp. OR CT brain.mp. OR brain imaging.mp. or exp Neuroimaging/] LIMIT to human AND English Language.
The Cochrane Library Issue 9 of 12 September 2019: MeSH descriptor: [Drowning] explode all trees.
Both searches identified 404 papers. Of these, three were considered relevant to the three-part question. No relevant reviews were found in the Cochrane library. (table 2)
All the reports agree that a normal cranial CT scan within 24 hours offers little prognostic value. However, they also agree that an abnormal cranial CT within 24 hours indicates a poor prognosis, and suggest avoiding aggressive treatment in these patients. The large study by Rafaat et al found that no patient with a GCS>4 had an abnormal CT scan, suggesting little need for the investigation in these patients.
Brain damage from drowning is caused by hypoxia and ischaemia. CT and MRI findings are summarised by Restrepo et al 4. The findings are different according to the age of the patient. Classic hypoxia-associated diffuse loss of grey-white differentiation, effacement of the sulci and decreased density of the basal ganglia is seen in adults. In the studies by Rafaat et al and Romano et al about 80% of the initial CT scans were normal. In the study by Rafaat et al 54% of those who developed abnormalities on a later CT scan died and 42% developed a persistent vegetative state.
In practical terms anyone presenting with a GCS 3 or 4 should have an initial CT brain scan. Others who have been intubated and ventilated could have a delayed CT if they fail to wake up normally after a sedation hold once their chest has improved.
Clinical bottom line
Cranial CT should be reserved for patients with a GCS≤4 in near drowning situations. An abnormal result indicates a very poor prognosis and may suggest avoidance of aggressive treatment.