Intrathoracic pressure regulation therapy applied to ventilated patients for treatment of compromised cerebral perfusion from brain injury

Abstract

Background: Reducing intrathoracic pressure in the setting of compromised cerebral perfusion due to acute brain injury has been associated with reduced intracranial pressure and enhanced cerebral perfusion pressure and blood flow in animals. Noninvasive active intrathoracic pressure regulation lowers intrathoracic pressure, increases preload, reduces the volume of venous blood and cerebral spinal fluid in the skull, and enhances cerebral blood flow. We examined the feasibility of active intrathoracic pressure regulation therapy in patients with brain injury. We hypothesized that active intrathoracic pressure regulation therapy would be associated with lowered intracranial pressure and increased cerebral perfusion pressure in these patients.

Methods: At three institutions, active intrathoracic pressure regulation therapy (CirQlator™, ZOLL) was utilized for 2 consecutive hours in five mechanically ventilated patients with brain injury. A 30-minute interval was used to collect baseline data and determine persistence of effects after device use. End-tidal carbon dioxide was controlled by respiratory rate changes during device use. The intracranial pressure, mean arterial pressure, and cerebral perfusion pressure were recorded at 5-minute intervals throughout all three periods of the protocol. Results for each interval are reported as mean and standard deviation.

Results: Intracranial pressure was decreased in all five patients by an average of 21% during (15 ± 4 mmHg) compared to before active intrathoracic pressure regulation (19 ± 4) (p = 0.005). This effect on intracranial pressure (15 ± 6) was still present in four of the five patients 30 minutes after therapy was discontinued (p = 0.89). As a result, cerebral perfusion pressure was 16% higher during (81 ± 10) compared to before active intrathoracic pressure regulation (70 ± 14) (p = 0.04) and this effect remained present 30 minutes after therapy was discontinued. No adverse events were reported.

Conclusions: These data support the notion that active intrathoracic pressure regulation, in this limited evaluation, can successfully augment cerebral perfusion by lowering intracranial pressure and increasing mean arterial pressure in patients with mild brain injury. The measured effects were immediate on administration of the therapy and persisted to some degree after the therapy was terminated.

Keywords: Blood gas analysis; Critical care; Critical illness; Hemodynamics/physiology; Humans; Intracranial hypertension; Intracranial pressure; Life support care/methods; Nervous system diseases; Neurology; Pressure; Traumatic brain injury.

Fig. 1

Active intrathoracic pressure regulation device (CirQlator™, ZOLL) used in the study to provide active intrathoracic pressure regulation therapy. The device is connected between a ventilation source and the patient’s airway circuit and the vacuum port tubing is connected to a regulated vacuum source. aIPR active intrathoracic pressure regulation, ETCO₂ end-tidal carbon dioxide

Fig. 2

Study timeline. ABG arterial blood gas analysis, aIPR active intrathoracic pressure regulation

Fig. 3

Key hemodynamic parameters at the end of each period (mean ± standard deviation, mmHg) before, during, and after active intrathoracic pressure regulation use. aIPR active intrathoracic pressure regulation, CerPP cerebral perfusion pressure, ICP intracranial pressure, MAP mean arterial pressure, * p = 0.005 and ** p = 0.04 between “before active intrathoracic pressure regulation” versus “during active intrathoracic pressure regulation”

Fig. 4

Key hemodynamic parameter changes for each participant. ↑ or ↓ indicates the number of patients whose values increased or decreased following each experimental condition. aIPR active intrathoracic pressure regulation, CerPP cerebral perfusion pressure, ICP intracranial pressure, MAP mean arterial pressure, STLM patients treated at Mercy Hospital (St. Louis, MO), UC a patient treated at University of Colorado Hospital (Aurora, CO), UTSW patients treated at University of Texas Southwestern Medical Center (Dallas, TX)