Implied Consent

Hypothetical Case: An elderly woman presents with the witnessed onset of acute right sided weakness 25 minutes ago. She has afib but doesn’t take warfarin. Exam shows her to be mute, with a leftward gaze preference, right hemianopia, and right hemiparesis graded 3/5 proximally and 2/5 distally in the arm and 5-/5 in the leg. NIHSS score is 14. Head CT shows a hyperdense left MCA, but no early ischemic change. She was brought in by a friend, who reports that the patient lives alone. She has no POA and no known next of kin.

1. Should you give IV tPA?
2. Should you refer her for endovascular treatment?


Among neurologists, I think most would agree to give IV tPA. It is the only FDA-approved treatment for ischemic stroke that is proven to result in better functional outcome. Its use is endorsed by the American Academy of Neurology and the American Stroke Association. Regarding consent, the AAN has recently issued a policy endorsing the administration of tPA in emergency situations under the implied consent doctrine. I recently participated in a Continuum Audio panel discussion regarding this issue.

The more difficult question is whether the implied consent doctrine applies to endovascular treatment. This actually breaks into two questions: IA treatment alone and IA treatment following IV.

IA Treatment Alone

In the arguably outdated 2007 ASA guideline, IA thrombolysis is given a class I (benefit >> risk) level B (limited populations studied) recommendation for patients presenting in a 6 hour window (p. 1678). Mechanical embolectomy carries class IIb (benefit ≥ risk) levels B and C recommendations (p. 1684).

One may argue, then, that IA lysis within 6 hours is sufficiently recommended to warrant its provision under the implied consent doctrine. However, it must be noted that the AAN policy above does not apply to IA therapy–only IV. In the panel discussion I participated in, Dr. Michael Williams, an ethicist and neurocritical care physician specifically highlighted this.

In addition, IV tPA should not be withheld from eligible patients in order to offer IA therapy instead (p. 1678), so in this hypothetical case, we’re really faced with the question of IV+IA.

IV tPA Followed by IA Therapy

Here, the Stroke Association guideline is even more clear–combination therapy receives a class III (risk > benefit) level B recommendation (p. 1685). Of course, that was 2007 and a lot of work has been done since then. Unfortunately, the IMS III study, a randomized trial of IV alone vs. IV + IA, was recently halted by its data safety and monitoring board for lack of efficacy (and not for safety concerns). So, although we still offer combined therapy to highly selected patients, I think its very clear that this shouldn’t be done on an implied consent basis.

Disclaimer: I’m not a lawyer; the above is a discussion of the medical evidence pertaining to these issues, along with some recent policy guidance. Missing here is a discussion of Wisconsin statutory and case law regarding the reliance on implied consent. If I can get such input, I’ll post a follow-up.

Update 8/27/13: Fixed the broken link to the AAN statement on implied consent.

About Justin A. Sattin

I'm a vascular neurologist and residency program director. I created this blog in order to share some thoughts with my resident and other colleagues, and to foster my own learning as well.
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