Effects of an Inspiratory Impedance Threshold Device on Blood Pressure and Short Term Survival in Spontaneously Breathing Hypovolemic Pigs
Abstract
Background: The inspiratory impedance threshold device (ITD) has been shown to improve hemodynamic variables and survival outcomes during cardiopulmonary resuscitation in animals and humans. We hypothesized that use of an ITD, with a resistance of 10cm H 2 O, will improve hemodynamics and short-term survival rates during hypovolemic hypotension in spontaneously breathing pigs. Methods: Female farm pigs ( approximately 26kg) were intubated and anesthetized with propo- fol with the dose adjusted to permit spontaneous respirations. They were bled to 50% of calculated blood volume through an arterial catheter and then prospectively randomized to either treatment with an ITD or observation alone. Arterial and intratracheal pressures as well as arterial blood gases were measured. After 90min the ITD was removed, normal saline was administered to all surviving animals, the anesthetic was discontinued, and animals were allowed to recover. Statistical analysis was performed with one-way repeated ANOVA and survival rates were calculated with Kaplan-Meier analysis. Treatment with ITD resulted in lower intracranial inspiratory pressure in the treatment group (-11 + or - 0.4 mmHG verses 4 + or - 0.7mmHg, respectively, P less than 0.005). Mean arterial pressure after 30min of treatment with the ITD was higher in the treatment group (61.1 + or - 5.5mmHg versus 37.4 + or - 2.1mmHG respectively, P less than 0/005). All pigs in the control group died within 65 min of the initial bleed, whereas 7/8 (87%) treated with an ITD survived for >90min ( P less than 0.001). During the recovery phase, 6/8 (75%) in the ITD group survived for greater than 3h and awoke without neurological deficit; one surviving animal in the ITD group never woke up. Arterial oxygenation was not compromised in the ITD group. Conclusions: Use of an ITD improved blood pressure and short-term survival rates in a spontaneously breathing porcine model of hypovolemic hypotension.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 2006
- Accession Number
- ADA627951
Entities
People
- David G. Benditt
- Demetris Yannopoulos
- Gardar Sigurdsson
- Jill L. Sondeen
- Keith G. Lurie
- Scott H. Mcknite
Organizations
- United States Army Institute of Surgical Research