The New ITD-7: Inspiratory impedance aids trauma patients


A.J. Heightman, MPA, EMT-P | From the August 2009 Issue | Friday, July 31, 2009

I remember the call as if it was yesterday. It was 1968, and I was a young, impressionable Advanced First-Aider riding with my EMT dad. A service station owner locked himself out of his station with the day_s cash receipts bundled in plain view on a desk, so he broke a window to re-enter. As he crawled through the window, he slipped, and a sharp piece of glass penetrated his abdomen.

The call remains etched in my mind after all these years because of what my father did to keep the man alive. First, before I could finish opening a single pack of 4 x 4s to placeon the wound, he took a large roller gauze and placed it deepinside the gaping wound. Then, he folded a sheet into a long, narrow bandage, placed it around the patient_s abdomen and tied it tightly over the wound to apply more pressure.

He later told me he had been taught by surgeons that thebest way to control bleeding of this nature was to get as close to the source of bleeding as possible and maintain maximum pressure on the injury site. He said, "This man would have died if he had a pretty, textbook dressing simply placedon the wound."

His next actions left even more of an impression on me. In addition to administering high-flow oxygen to the patient to feed the patient_s blood- and oxygen-deprived organs, my father encouraged him to purse his lips to inhale and "bite the bullet," clench his teeth and grunt when the pain got unbearable. The patient complied with my dad_s every instruction. As he inhaled the oxygen in a slightly restricted manner and grunted occasionally, it was amazing to watch his color, BP and mental status improve, and his pain decrease.

As we cleaned the ambulance after the call, I asked about the pursed-lip inspirations and grunting requests. He explained that the term "bite the bullet" was derived from the days before anesthesia, when soldiers were given bullets to bite on to help them endure pain, which I_ve since found to be true. He said his own experience had shown that inspirations through pursed lips often improved the patient_s color and blood pressure and that grunting often decreased the patient_s pain.

This memory is why I was excited to read a research paper in the Spring issue of theJournal of Special Operations Medicine. The article_s title tells the whole story: "The Impedance Threshold Device (ITD-7): A new device for combat casualty care to augment circulation and blood pressure in hypotensive spontaneously breathing warfighters." Tested extensively in animal models of hemorrhagic shock and heat stroke, the ResQGARD inspiratory ITD has been shown to improve hemodynamic variables and short-term survival rates during hypovolemic hypotension when inspiratory impedance is applied to its breathing circuit.

The small breathing circuit causes the patient to breathe through 7 cm HO resistance (negative pressure) which, in turn, causes an increase in venous blood flow back to the heart and a subsequent increase in cardiac output and blood pressure. It also reduces intracranial pressure with each inspiration, thereby providing greater blood flow to the brain.

In the absence of an IV, hypotensive patients have shown immediate benefit from the device, with a 10 mmHg rise in their mean arterial pressure within five to 10 minutes. When fluid resuscitation was given concurrently, BPs rose even faster, by 20 mmHg within 10 minutes.

Designed to be used on trauma patients with a systolic BP < 110 mmHg, or those who feel faint or lightheaded, the ResQGARD circuit can be deployed on a provided facemask or mouthpiece, or on a bag-valve mask (for assisted ventilations). Because of the relatively small increase in work needed to breathe through the ResQGARD, it can be well tolerated for 30Ï60 minutes.

The military is excited about this new FDA-approved device because it will allow them to "buy time" for patients in the war theater, where other therapies aren_t readily available. I_m excited about it because it can be used by BLS and ALS providers to increase the BP, cardiac output and blood flow to the brain of hypotensive, spontaneously breathing trauma patients anywhere.

I also like this device because it shows my dad was once again ahead of the clinical curve back in the days of pure BLS and scoop-and-run EMS.JEMS

  2. Parsons D, Convertino V, Idris A, et al: "The Impedance Threshold Device (ITD-7): A new device for combat casualty care to augment circulation and blood pressure in hypotensive spontaneously breathing warfighters." Journal of Special Operations Medicine. 9(2):49Ï52, 2009.

  3. Sigurdssona G, Yannopoulosa D, McKnitea S, et al: "Effects of an inspiratory impedance threshold device on blood pressure and short term survival in spontaneously breathing hypovolemic pigs." Resuscitation. 68(3):399Ï404, 2006.

Connect: Have a thought or feedback about this? Add your comment now
Related Topics: Patient Care, Cardiac and Circulation, Jems From the Editor

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A.J. Heightman, MPA, EMT-P

JEMS Editor-in-Chief A.J. Heightman, MPA, EMT-P, has a background as an EMS director and EMS operations director. He specializes in MCI management.


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