Effect of an inspiratory impedance threshold device on hemodynamics during conventional manual cardiopulmonary resuscitation

Ronald G. Pirrallo, Tom P. Aufderheide, Terry A. Provo, Keith G. Lurie

Research output: Contribution to journalArticlepeer-review

78 Scopus citations


Background: In animals in cardiac arrest, an inspiratory impedance threshold device (ITD) has been shown to improve hemodynamics and neurologically intact survival. The objective of this study was to determine whether an ITD would improve blood pressure (BP) in patients receiving CPR for out-of-hospital cardiac arrest. Methods: This prospective, randomized, double-blind, intention-to-treat study was conducted in the Milwaukee, WI, emergency medical services (EMS) system. EMS personnel used an active (functional) or sham (non-functional) ITD on a tracheal tube on adults in cardiac arrest of presumed cardiac etiology. Care between groups was similar except for ITD type. Low dose epinephrine (1 mg) was used per American Heart Association Guidelines. Femoral arterial BP (mmHg) was measured invasively during CPR. Results: Mean ± S.D. time from ITD placement to first invasive BP recording was approximately 14 min. Twelve patients were treated with a sham ITD versus 10 patients with an active ITD. Systolic BPs (mean ± S.D.) [number of patients treated at given time point] at T = 0 (time of first arterial BP measurement), and T = 2, 5 and 7 min were 85 ± 29 [10], 85 ± 23 [10], 85 ± 16 [9] and 69 ± 22 [8] in the group receiving an active ITD compared with 43 ± 15 [12], 47 ± 16 [12], 47 ± 20 [9], and 52 ± 23 [9] in subjects treated with a sham ITD, respectively (p < 0.01 for all times). Diastolic BPs at T = 0, 2, 5 and 7 min were 20 ± 12, 21 ± 13, 23 ± 15 and 25 ± 14 in the group receiving an active ITD compared with 15 ± 9, 17 ± 8, 17 ± 9 and 19 ± 8 in subjects treated with a sham ITD, respectively (p = NS for all times). No significant adverse device events were reported. Use of the active ITD was found to increase systolic pressures safely and significantly in patients in cardiac arrest compared with sham controls.

Original languageEnglish (US)
Pages (from-to)13-20
Number of pages8
Issue number1
StatePublished - Jul 2005
Externally publishedYes

Bibliographical note

Funding Information:
Tom Aufderheide, MD: Dr. Aufderheide has served as Basic Life Support Science Editor for the National American Heart Association (paid position). He has received research funding from: (1) GE/Marquette Medical Systems Inc., for a 12-SL Ischemia Project; (2) National Heart, Lung and Blood Institute (NHLBI) SBIR for the current study; (3) NHLBI for the Public Access Defibrillation (PAD-1) Trial, (4) NHLBI for the Resuscitation Outcomes Consortium, and (5) NHLBI for the IMMEDIATE Trial. He is a paid consultant to Medtronic Physio-Control, has served as an ad hoc consultant to GE/Marquette Medical Systems Inc. and ZOLL Medical Inc., and has served in the SBIR study section for the NHLBI.

Funding Information:
The authors gratefully acknowledge the assistance of the following individuals whose enthusiasm, dedication and patience made this project possible: Research Team: Chris von Briesen, BA, EMT; Christopher W. Sparks, EMT; David J. Kitscha, BS, MS; Craig J. Conrad, RN; Kimberly A. Deja, RN; Milwaukee County Department of Health and Human Services: Paula Lucey; Milwaukee County Division of EMS Administration: Patricia Haslbeck, Rosemarie Forster, Michael Milbrath, Lauryl Pukansky, Kenneth Sternig; Milwaukee County EMS Faculty: Bernadette Barton, Angela Brindowski, Eugene Chin, Kim Krueger, Del Szewczuga; Milwaukee County EMS Staff: Thomas Duerr, Rebecca Funk, Gail Jacobsen, Karin Lerner; Milwaukee Fire Department: Chief William Wentlandt, Deputy Chief Gloria Murawsky, Battalion Chief Donn Preston, Captain Sean Slowey, Lieutenant Doran Kemp; Hemodynamic Research Team Physicians: Drs. Renée Foutz, Melody Graves, Kyle Hansen, William Lieber, Michael Uihlein, Lana Tomes, Michael Bourn, Suzanne Martens, Karl Anderson, J. Michael Roseberry, Kenneth Yen, Subhankar Bandyopadhyay, William Smith, Stephen Shipley, Robert Bryant, Michael Beins; Paramedic Planning Group: David Anderson, John Emerson, Tom Grosser, Russell Jacobsen. Most importantly, we thank the paramedics and EMTs of the Milwaukee County EMS System for their passion for improving the health and safety of our community. We also thank Ms. Dawn Kawa for her valuable and gracious assistance in the preparation of this manuscript. Funding for this study was provided by the National Institute of Health (NIH) SBIR grants #2-R44-HL65851-02 and #3-R44-HL65851-02-S1 to Advanced Circulatory Systems Inc., Eden Prairie, MN; Keith Lurie, MD, principal investigator.


  • Blood pressure
  • Cardiac arrest
  • Cardiopulmonary resuscitation
  • Circulation
  • Emergency medical services
  • Impedance threshold device


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