Simultaneous ring voice-over-Internet phone system enables rapid physician elicitation of explicit informed consent in prehospital stroke treatment trials

Cerebrovasc Dis. 2009;28(6):539-44. doi: 10.1159/000247596. Epub 2009 Oct 16.


Background: Cellular phone conversations between on-scene patients or their legally authorized representatives (LARs) and off-scene enrolling physician-investigators require immediate and reliable connection systems to obtain explicit informed research consent in prehospital treatment trials.

Methods: The NIH Field Administration of Stroke Therapy-Magnesium (FAST-MAG) Trial implemented a voice-over-internet protocol (VOIP) simultaneous ring system (multiple investigator cell phones called simultaneously and first responder connected to call) to enable physician-investigators to elicit consent immediately from competent patients or LARs encountered by 228 ambulances enrolling patients in a multicenter prehospital stroke trial. For 1 month, the number, origin, duration, and yield of enrolling line calls were monitored prospectively.

Results: Six investigators were connected to 106 enrolling line calls, with no identified unanswered calls. Thirty-five percent of new patient calls yielded an enrollment. The most common reasons for non-enrollment were last known well >2 h (n = 7) and unconsentable patient without LAR available (n = 7). No non-enrollments were directly attributable to the VOIP system. In enrollments, consent was provided by the patient in 67% and a LAR in 33%. The duration of enrollment calls (mean +/- SD: 8.4 +/- 2.5 min, range 6-14) was longer than non-enrollment calls (5.5 +/- 3.5, range 2-13; p < 0.001). The median interval from last known well to study agent start was 46 min, and 70% were enrolled within 60 min of onset.

Conclusions: The simultaneous ring system was reliable and effective, permitting enrollment of a substantial number of patients within the first hour after stroke onset. VOIP cellular networks with simultaneous ring are a preferred means of facilitating consent in prehospital treatment trials.

Publication types

  • Multicenter Study
  • Research Support, N.I.H., Extramural

MeSH terms

  • Aged
  • Calcium Channel Blockers / therapeutic use
  • Cell Phone*
  • Female
  • Humans
  • Informed Consent*
  • Internet*
  • Los Angeles
  • Magnesium Sulfate / therapeutic use
  • Male
  • National Institutes of Health (U.S.)
  • Physicians*
  • Prospective Studies
  • Randomized Controlled Trials as Topic / methods*
  • Stroke / drug therapy*
  • Time Factors
  • United States


  • Calcium Channel Blockers
  • Magnesium Sulfate