IRB-HSR# 14299: The Use of the Intrathoracic Pressure Regulator (ITPR) to Improve Cerebral Perfusion Pressure in Patients With Altered Intracranial Elastance

Traumatic Brain Injury Clinical Trial

Official title:

IRB-HSR# 14299: The Use of the Intrathoracic Pressure Regulator (ITPR) to Improve Cerebral Perfusion Pressure in Patients With Altered Intracranial Elastance

Clinical Trial Details — Status: Enrolling by invitation

Administrative data

• NCT number: NCT01205607
• Other study ID #: 14299
• Status: Enrolling by invitation
• Phase: Phase 2
• First received: September 17, 2010
• Last updated: September 17, 2010
• Start date: May 2009

Study information

• Verified date: September 2010
• Source: University of Virginia
• Contact: n/a
• Is FDA regulated: No
• Health authority: United States: Institutional Review Board
• Study type: Interventional

Clinical Trial Summary

Patients who have a functioning intracranial pressure-monitoring device (either a subarachnoid bolt, or an intraventricular catheter) in place, and are either sedated, intubated, and mechanically ventilated (i.e. in the NNICU), or are scheduled to undergo an operation or interventional neuroradiological procedure at the University of Virginia. Patients with a contraindication to TTE will be excluded.

For patients in the NNICU, basic hemodynamic variables (systemic blood pressure, central venous pressure, etc.) will be collected. In addition, left ventricular performance (including estimates of LVEDV, LVESV, EF, FAC, and SV) will be assessed using TTE. Once these baseline data are recorded, the ITPR will be inserted in the ventilator circuit and activated to provide either -5 mm Hg or -9 mm Hg endotracheal rube pressure (ETP) (based on a randomization scheme). After the ITPR has been active for at least five minutes, the same intracranial, hemodynamic, and TTE data obtained above will be gathered. The ITPR will then be turned off for five minutes, and intracranial, hemodynamic, and TTE data will again be recorded. The ITPR will be activated a second time (-9 mm Hg or -5 mm Hg ETP, i.e. whichever value was not used previously), and after five minutes of use data will be recorded again. The ITPR will then be disconnected, data will be collected after waiting two minutes, and no further interventions will be made.

ABG's will be obtained before and during the use of the device at each setting.

This is a proof of concept/feasibility study designed to test the primary hypothesis that use of the ITPR will result in decreased intracranial pressure and increased cerebral perfusion pressure. The effect of the ITPR on secondary indicators of cardiac performance will also be examined. These include but are not limited estimates of ventricular end diastolic volume and pressure (LVEDV/P), ejection fraction (EF), left ventricular end systolic volume and pressure (LVESV/P), fractional area change (FAC), all of which will be assessed by transthoracic echocardiography (TTE) or transesophageal echocardiography (TEE).

Description:

The ITPR is an FDA-approved device intended to increase circulation and blood pressure in hypovolemic and cardiogenic shock. The device is inserted within a standard respiratory circuit between the patient and the ventilator. It functions by decreasing intrathoracic pressure during the expiratory phase to subatmospheric levels after each positive pressure ventilation. This decrease in intrathoracic pressure creates a vacuum within the thorax relative to the rest of the body, thereby enhancing venous return to the heart and consequently increasing cardiac output and blood pressure. Activation of the device is also accompanied by a decrease in SVR. The end result is a device that simultaneously improves cardiac output by increasing LVEDV and decreasing SVR while increasing coronary perfusion pressure by increasing blood pressure and decreasing LVESP/LVESV.1-8

Interestingly, while the ITPR was developed as a non-invasive mechanism to increase preload in hypovolemic patients, its mechanism of action (generation of subatmospheric intrathoracic pressure) has been shown to reduce intracranial pressure6. This is critical in brain-injured patients, because elevated intracranial pressure is strongly associated with poor outcome in traumatic brain injury (TBI) patients - in a recent study of 846 TBI patients, those with ICP < 20 mm Hg by 48 hours had a mortality rate of 14%, whereas those with ICP > 20 mm Hg had a mortality rate of 34%9. Particularly interesting are the ITPR's combined benefits of increased MAP and decreased ICP, as hypotension is a well-known poor prognostic indicator in this patient population.

In fact, according to the Brain Trauma Foundation Guidelines, "Hypotension, occurring at any time from injury through the acute intensive care course, has been found to be a primary predictor of outcome from severe head injury for the health care delivery systems within which prognostic variables have been best studied. Hypotension is repeatedly found to be one of the five most powerful predictors of outcome and is generally the only one of these five that is amenable to therapeutic modification. A single recording of a hypotensive episode is generally associated with a doubling of mortality and a marked increase in morbidity from a given head injury10."

Importantly, cerebral perfusion pressure (mean arterial pressure - the greater of ICP or CVP) is only a surrogate marker for cerebral blood flow. The function of hypotension as a useful clinical variable is dependent on two factors - first, its correlation with the true variable of interest (cerebral blood flow) and second, the ability of clinicians to manipulate the underlying variable of interest (cerebral blood flow) based on the surrogate marker (cerebral perfusion pressure).

The acceptable level of hypotension in patients with brain injuries has not been determined, and the Brain Trauma Foundation (BTF) Guidelines recommend maintaining systolic blood pressures > 90 mm Hg, but acknowledge that this number is relatively arbitrary and not based on any high-level studies (thus assigning it a designation of Level II evidence) 11. The BTF Guidelines further state that because hypotension is such a poor prognostic variable, it would be unethical to randomize patients to various blood pressure goals, and therefore Level I evidence is not forthcoming. Further complicating the situation is the lack of agreement on how to increase blood pressure (with the hopes of increasing cerebral perfusion pressure)12-15. Many of the pharmacologic agents used to increase mean arterial pressure have significant vasoconstrictive effects, which could counteract any increase blood pressure and lead to unchanged, or even reduced cerebral blood flow.

Recruitment information / eligibility

• Status: Enrolling by invitation
• Enrollment: 20
• Accepts healthy volunteers: No
• Gender: Both
• Age group: 18 Years and older

Eligibility

Inclusion Criteria:

• 1. patients who have a functioning intracranial pressure-monitoring device (either a subarachnoid bolt, or an intraventricular catheter) in place, and are either sedated, intubated, and mechanically ventilated (i.e. in the NNICU)and have an arterial line in place, or are scheduled to undergo an operation or interventional neuroradiological procedure at the University of Virginia.

2. age 18 years of age and older 3. informed consent/ surrogate consent has been obtained

Exclusion Criteria:

• 1. pneumothorax 2. hemothroax 3. uncontrolled bleeding 4. uncontrolled hypertension defined as SBP > 180 mmHg at the time of surgery 5. known respiratory disease such as chronic emphysema, COPD, or Cystic Fibrosis

Study Design

Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Parallel Assignment, Masking: Double Blind (Subject, Outcomes Assessor), Primary Purpose: Health Services Research

Related Conditions & MeSH terms

• Brain Injuries
• Traumatic Brain Injury

Intervention

Device:
• ITPR -5 mm Hg then -9 mm Hg
the ITPR will be inserted in the ventilator circuit and activated to provide either -5 mm Hg or -9 mm Hg endotracheal tube pressure (ETP) Each subject will have all measurements recorded at both -5 & -9 mm Hg
• ITPR -9 & then -5mm Hg
the ITPR will be inserted in the ventilator circuit and activated to provide either -5 mm Hg or -9 mm Hg endotracheal tube pressure (ETP) Each subject will have all measurements recorded at both -5 & -9 mm Hg

Locations

Country	Name	City	State
United States	University of Virginia Health System	Charlottesville	Virginia

Sponsors (1)

Lead Sponsor	Collaborator
University of Virginia

Country where clinical trial is conducted

United States, 

References & Publications (15)

Alspaugh DM, Sartorelli K, Shackford SR, Okum EJ, Buckingham S, Osler T. Prehospital resuscitation with phenylephrine in uncontrolled hemorrhagic shock and brain injury. J Trauma. 2000 May;48(5):851-63; discussion 863-4. — View Citation

Bratton SL. Chestnut RM. Ghajar J et al.: I. Blood Pressure and Oxygenation. J Neurotrauma 24 (S1): S7-S13, 2007

Dudkiewicz M, Proctor KG. Tissue oxygenation during management of cerebral perfusion pressure with phenylephrine or vasopressin. Crit Care Med. 2008 Sep;36(9):2641-50. doi: 10.1097/CCM.0b013e3181847af3. — View Citation

Jiang JY, Gao GY, Li WP, Yu MK, Zhu C. Early indicators of prognosis in 846 cases of severe traumatic brain injury. J Neurotrauma. 2002 Jul;19(7):869-74. — View Citation

Lurie KG, Mulligan KA, McKnite S, Detloff B, Lindstrom P, Lindner KH. Optimizing standard cardiopulmonary resuscitation with an inspiratory impedance threshold valve. Chest. 1998 Apr;113(4):1084-90. — View Citation

Lurie KG, Voelckel WG, Zielinski T, McKnite S, Lindstrom P, Peterson C, Wenzel V, Lindner KH, Samniah N, Benditt D. Improving standard cardiopulmonary resuscitation with an inspiratory impedance threshold valve in a porcine model of cardiac arrest. Anesth Analg. 2001 Sep;93(3):649-55. — View Citation

Lurie KG, Zielinski T, McKnite S, Aufderheide T, Voelckel W. Use of an inspiratory impedance valve improves neurologically intact survival in a porcine model of ventricular fibrillation. Circulation. 2002 Jan 1;105(1):124-9. — View Citation

Lurie KG, Zielinski TM, McKnite SH, Idris AH, Yannopoulos D, Raedler CM, Sigurdsson G, Benditt DG, Voelckel WG. Treatment of hypotension in pigs with an inspiratory impedance threshold device: a feasibility study. Crit Care Med. 2004 Jul;32(7):1555-62. — View Citation

Myburgh JA. Driving cerebral perfusion pressure with pressors: how, which, when? Crit Care Resusc. 2005 Sep;7(3):200-5. — View Citation

Pfister D, Strebel SP, Steiner LA. Effects of catecholamines on cerebral blood vessels in patients with traumatic brain injury. Eur J Anaesthesiol Suppl. 2008;42:98-103. doi: 10.1017/S0265021507003407. Review. — View Citation

The Brain Trauma Foundation. The American Association of Neurological Surgeons. The Joint Section on Neurotrauma and Critical Care. Hypotension. J Neurotrauma. 2000 Jun-Jul;17(6-7):591-5. Review. — View Citation

Yannopoulos D, McKnite S, Metzger A, Lurie KG. Intrathoracic pressure regulation improves 24-hour survival in a porcine model of hypovolemic shock. Anesth Analg. 2007 Jan;104(1):157-62. — View Citation

Yannopoulos D, McKnite SH, Metzger A, Lurie KG. Intrathoracic pressure regulation for intracranial pressure management in normovolemic and hypovolemic pigs. Crit Care Med. 2006 Dec;34(12 Suppl):S495-500. — View Citation

Yannopoulos D, Metzger A, McKnite S, Nadkarni V, Aufderheide TP, Idris A, Dries D, Benditt DG, Lurie KG. Intrathoracic pressure regulation improves vital organ perfusion pressures in normovolemic and hypovolemic pigs. Resuscitation. 2006 Sep;70(3):445-53. Epub 2006 Aug 9. — View Citation

Yannopoulos D, Nadkarni VM, McKnite SH, Rao A, Kruger K, Metzger A, Benditt DG, Lurie KG. Intrathoracic pressure regulator during continuous-chest-compression advanced cardiac resuscitation improves vital organ perfusion pressures in a porcine model of cardiac arrest. Circulation. 2005 Aug 9;112(6):803-11. Epub 2005 Aug 1. — View Citation

* Note: There are 15 references in all — Click here to view all references

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Hemodynamic variables	hemodynamic variables (systemic blood pressure, central venous pressure, ICP) will be collected at baseline, 5 minutes after device activation & 5 minutes after device turned off	baseline, 5 minutes after device activation & 5 minutes after device turned off	No
Secondary	cardiac performance	cardiac performance will also be examined. These include but are not limited estimates of ventricular end diastolic volume and pressure (LVEDV/P), ejection fraction (EF), left ventricular end systolic volume and pressure (LVESV/P), fractional area change (FAC)	baseline, 5 minutes after device activation & 5 minutes after device turned off	No