An impedance threshold device increases blood pressure in hypotensive patients

Stephen W. Smith, Brent Parquette, David Lindstrom, Anja K. Metzger, Joni Kopitzke, Joseph Clinton

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Background: The impedance threshold device (ITD-7) augments the vacuum created in the thorax with each inspiration, thereby enhancing blood flow from the extrathoracic venous systems into the heart. Objectives: To the best of our knowledge, the ITD-7 has not previously been investigated in hypotensive patients in the emergency department (ED) or the prehospital setting. The objective of this study was to determine whether the ITD-7 would increase systolic arterial pressures in hypotensive spontaneously breathing patients. Methods: The ED study was a prospective, randomized, double-blind, sham control design. Patients with a systolic blood pressure ≤ 95 mm Hg were randomized to breathe for 10 min through an active or sham ITD. The primary endpoint was the change in systolic blood pressure measured non-invasively. The prehospital study was a prospective, non-blinded evaluation of the ITD-7 in hypotensive patients. Results: In the ED study, the mean ± standard deviation rise in systolic blood pressure was 12.9 ± 8.5 mm Hg for patients (n = 16) treated with an active ITD-7 vs. 5.9 ± 5.9 mm Hg for patients (n = 18) treated with a sham ITD-7 (p < 0.01). In the prehospital study, the mean systolic blood pressure before the ITD-7 was 79.4 ± 10.2 mm Hg and 107.3 ± 17.6 mm Hg during ITD-7 use (n = 47 patients) (p < 0.01). Conclusion: During this clinical evaluation of the ITD-7 for the treatment of hypotensive patients in the ED and in the prehospital setting, use of the device significantly increased systolic blood pressure and was safe and generally well tolerated.

Original languageEnglish (US)
Pages (from-to)549-558
Number of pages10
JournalJournal of Emergency Medicine
Issue number5
StatePublished - Nov 2011

Bibliographical note

Funding Information:
This project was supported in large part by Department of Defense Small Business Innovative Research (SBIR) Grant # W81XWH-04-C-0022 .

Copyright 2012 Elsevier B.V., All rights reserved.


  • dehydration
  • hemorrhage
  • hypotension
  • impedance threshold device
  • sepsis


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