Greater Sydney Area HEMS

OXY’s LOG – ‘Not your typical anti-psychotic’

Quetiapine Overdose

Case: A young adult male was found comatosed after suspected overdose. His regular medications included quetiapine. He required interhospital retrieval to a tertiary care facility. He was intubated and ventilated but required only minimal sedation.

Challenge: To discover the issues surrounding quetiapine overdose.

Learning points: Quetiapine is an atypical antipsychotic used in the treatment of schizophrenia. The main clinical findings in quetiapine overdose (resulting from α-adrenergic and histamine receptor blockade) are hypotension, tachycardia, and coma. The potentially life-threatening consequences from overdose include QT prolongation and respiratory depression.

The only deaths that have been reported have occurred in patients with other co-morbidites.

There is no specific antidote, and quetiapine overdose is managed by appropriate supportive measures. Ventilation is often required. Out of all the anti-psychotics, quetiapine causes the most hypotension in overdose and the patient should be monitored closely for cardiac dysrhythmias.

Reference: Ngo A, Ciranni M, Olson KR. Acute quetiapine overdose in adults: A 5-year retrospective case series. Annals of Emergency Medicine 2008; Volume 52, Issue 5, Pages 541-547.

10.1016/j.annemergmed. 2008.03.016

OXY’s LOG – Subarachnoid haemorrhage

Case: A middle aged male with acute subarachnoid haemorrhage presents to a hospital emergency department with a depressed conscious level following a sudden onset headache. He becomes increasingly unresponsive and requires intubation. A head CT reveals acute subarachnoid haemorrhage with hydrocephalus. He requires interhospital retrieval to a tertiary care facility

Challenge: He has a BP of 190/134 on arrival of the retrieval team. He is intubated and ventilated and on a propofol infusion at 120 mg/hr

Learning point: Hypertension is commonly present at the time of presentation of SAH. In one study rebleeding was more common in those with a systolic blood pressure >160 mm Hg, so some recommend controlling the BP to this target. Guidelines state: Blood pressure should be monitored and controlled to balance the risk of stroke, hypertension-related rebleeding, and maintenance of cerebral perfusion pressure¹

While antihypertensive drugs may be required, the good news is that adequate analgesia and sedation often do the trick. In this case, a fentanyl infusion was commmenced and the BP settled nicely.

Here’s an excerpt from the Neuroprotection Helicopter Operating Procedure:

4.6 SAH

4.6.1 In the case of unclipped aneurysmal SAH, the risk of re-bleeding in the first 24hr (7-17%) must be balanced against that of subsequent cerebral vasospasm and subsequent ischaemia which peak at 7-10 days.

4.6.2 Hypertension is commonly present at the time of presentation. The evidence is weak but supports targeting a SBP no higher than 160mmHg.

4.6.3 Following surgical management or endo-luminal coiling procedures, the emphasis shifts to maintaining cerebral perfusion, and a more permissive upper limit of BP may be acceptable, as with other forms of stroke.

4.6.4 Useful agents to control BP in this setting include:

optimising analgesia and sedation

esmolol or metoprolol

hydralazine

nimodipine infusion if preferred by neurosurgical team.

1. Guidelines for the Management of Aneurysmal Subarachnoid Hemorrhage: A Statement for Healthcare Professionals From a Special Writing Group of the Stroke Council, American Heart Association
Stroke 2009;40;994-1025 (Full Text)