Date: January 29th, 2020

Reference: Perry et al. Prospective Implementation of the Ottawa Subarachnoid Hemorrhage Rule and 6-Hour Computed Tomography Rule. Stroke 2019

Guest Skeptic: Dr. Rory Spiegel is an EM/CC doctor who splits his time in the Emergency Department and Critical Care department. He also has this amazing #FOAMed blog called EM Nerd.

Case: A 48-year-old male presents to your emergency department with a sudden onset headache, which started about one-hour prior to arrival. The headache is severe is quality and the patient does not have a history of similar headaches in the past. It is associated with nausea, vomiting and photophobia.

 Background: Headaches are a common complaint presenting to the emergency department.  Subarachnoid hemorrhage represents one of the most serious underlying causes of headaches and we have covered it a number of times on the SGEM:

* SGEM#48: Thunderstruck – Subarachnoid Hemorrhage

* SGEM#134: Listen, to what the British Doctors Say about LPs post CT for SAH

* SGEM#140: CT Scans to Rule Out Subarachnoid Hemorrhages in A Non-Academic Setting

* SGEM#201: It’s in the Way That You Use It – Ottawa SAH Tool

In patients who present neurologically intact making the diagnosis early is key to preventing subsequent more life-threatening bleeding. A number of controversies surround the diagnosis of SAH in the emergency department. Two of the more provocative are the use of the Ottawa SAH Rule and whether a lumbar puncture (LP) is required following a negative CT if the scan is performed within 6-hours of symptom onset.

The Ottawa SAH Rule (tool) was covered on SGEM#201. The bottom line from that study was that the clinical decision instrument needed external validation, a meaningful impact analysis performed and patient acceptability of incorporating this rule into a shared decision-making instrument before being widely adopted.

We were surprised that in their background/introduction material they did not include the excellent SRMA on this topic by Carpenter et al. AEM 2016.

Clinical Question: What is the clinical impact of the Ottawa SAH Rule and the 6-hour CT Rule compared to standard care when implemented in six emergency departments across Canada?

Reference: Perry et al. Prospective Implementation of the Ottawa Subarachnoid Hemorrhage Rule and 6-Hour Computed Tomography Rule. Stroke 2019

The senior author on this publication was the legend of emergency medicine, Dr. Ian Stiell from Ottawa.

* Population: Neurologically intact adult presenting to the ED with a chief complaint of a nontraumatic, acute headache, or syncope associated with a headache.

* Exclusions: Patients with any of the following:

3 or more previous similar headaches (ie, same intensity/character as their current headache) over a period of >6 months (eg, established migraines)

confirmed SAH before arrival at study ED