Use of the intrathoracic pressure regulator to lower intracranial pressure in patients with altered intracranial elastance: a pilot study

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Object

The intrathoracic pressure regulator (ITPR) is a novel noninvasive device designed to increase circulation and blood pressure. By applying negative pressure during the expiratory phase of ventilation it decreases intrathoracic pressure and enhances venous return, which increases cardiac output. It is possible that the ITPR may both decrease intracranial pressure (ICP) and increase cerebral perfusion pressure (CPP) in brain-injured patients by decreasing cerebral venous blood volume and increasing cardiac output. The authors conducted an open-label, “first-in-humans” study of the ITPR in patients with an ICP monitor or external ventricular drain and altered intracranial elastance.

Methods

This prospective randomized trial commenced July 2009. Baseline hemodynamic variables and ICP were recorded prior to inserting one of the two ITPRs into the ventilator circuit based on a randomization scheme. Depending on the device selected, activation provided either −5 or −9 mm Hg endotracheal tube pressure. Hemodynamic and ICP data were recorded sequentially every 2 minutes for 10 minutes. The first device was turned off for 10 minutes, then it was removed and the second device was applied, and then the procedure was repeated for the second device.

Results

Ten patients with elevated ICP secondary to intracranial hemorrhage (n = 4), trauma (n = 2), obstructive hydrocephalus (n = 2), or diffuse cerebral processes (n = 2) were enrolled. Baseline ICP ranged from 12 to 38 mm Hg. With device application, a decrease in ICP was observed in 16 of 20 applications. During treatment with the −5 mm Hg device, there was a mean maximal decrease of 3.3 mm Hg in ICP (21.7 vs 18.4 mm Hg, p = 0.003), which was associated with an increase in CPP of 6.5 mm Hg (58.2 vs 64.7 mm Hg, p = 0.019). During treatment with the −9 mm Hg device, there was a mean maximal decrease of 2.4 mm Hg in ICP (21.1 vs 18.7 mm Hg, p = 0.044), which was associated with an increase in CPP of 6.5 mm Hg (59.2 vs 65.7 mm Hg, p = 0.001).

Conclusions

This pilot study demonstrates that use of the ITPR in patients with altered intracranial elastance is feasible. Although this study was not powered to demonstrate efficacy, these data strongly suggest that the ITPR may be used to rapidly lower ICP and increase CPP without apparent adverse effects. Additional studies will be needed to assess longitudinal changes in ICP when the device is in use and to delineate treatment parameters.

Abbreviations used in this paper:ABG = arterial blood gas; CPP = cerebral perfusion pressure; EVD = external ventricular drain; ICH = intracranial hemorrhage; ICP = intracranial pressure; ITPR = intrathoracic pressure regulator; TBI = traumatic brain injury.

Article Information

Address correspondence to: Edward C. Nemergut, M.D., Department of Anesthesiology, University of Virginia Health System, P.O. Box 800710, Charlottesville, Virginia 22908-0710. email: en3x@virginia.edu.

Please include this information when citing this paper: published online May 24, 2013; DOI: 10.3171/2013.4.JNS122489.

© AANS, except where prohibited by US copyright law.

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Figures

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    Photograph showing the ITPR device within a standard respiratory circuit, between the ventilator and the endotracheal (ET) tube.

  • View in gallery

    Graphs showing maximal change in CPP from baseline (BL) by patient. Left: Results in 10 patients treated using the −5 mm Hg ITPR. Right: Results in 10 patients treated using the −9 mm Hg ITPR. Cases are numbered and graphed according to the intracranial process: trauma (T1, T2); ICH (ICH1–4); obstructive hydrocephalus (OH1, OH2); and diffuse cerebral process (DCP1, DCP2).

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