An impedance threshold device increases blood pressure in hypotensive patients.
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.


OBJECTIVE
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).


CONCLUSIONS
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.
Smith
Stephen W
SW
Department of Emergency Medicine, Hennepin County Medical Center, Minneapolis, Minnesota 55415, USA. Smith253@umn.edu
Parquette
Brent
B
Lindstrom
David
D
Metzger
Anja K
AK
Kopitzke
Joni
J
Clinton
Joseph
J
D000328:Adult; D000368:Aged; D001794:Blood Pressure; D004311:Double-Blind Method; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D007022:Hypotension / Q000628:therapy*; D008297:Male; D008397:Masks; D008875:Middle Aged; D011175:Positive-Pressure Respiration / Q000295:instrumentation / Q000379:methods*; D011446:Prospective Studies; D012119:Respiration