Use of Respiratory Impedance in Prehospital Care of Hypotensive Patients Associated with Hemorrhage and Trauma: A Case Series.

摘要

The respiratory pump can be optimized to enhance circulation in patients with hypotension by having patients spontaneously breathe through a low level of inspiratory resistance. This can be achieved with an impedance threshold device (ITD) designed to provide 7 cm H2O resistance during spontaneous inspiration with minimal resistance during expiration. Little is known about the effects of harnessing this physiological concept to increase blood pressure (BP) in the prehospital setting of care for patients with hypotension caused by blood loss or trauma. In this case series, we report on the feasibility, effectiveness, and safety of rapidly deploying the ITD by first responders to treat hypotension secondary to blood loss and trauma in the urban setting by emergency medical services personnel. METHODS: Hemodynamic data from hypotensive patients (pretreatment systolic BP [SBP] G100 mm Hg) from 3 U.S. cities where the ITD is deployedwere evaluated. The primary end point was maximum change in SBP and diastolic BP (DBP) from before to during ITD use in patients with hypotension secondary to documented blood loss or trauma. Secondary end points were device tolerance, whether the patient felt better, change in heart rate, O2 saturation, and adverse events. RESULTS: Of the 255 hypotensive patients treated, there were 26 categorized with blood loss and 13 with trauma. In this 39-patient subgroup, the SBP and DBP (mean T SD) increased from 79 T 14mmHg and 48 T 12mmHg before ITD placement to 110 T 17 mmHg and 66 T 14mmHg after ITD placement (p G 0.001). Breathing through the ITD resulted in no reported adverse events, was well tolerated, and resulted in feeling better in more than 85% of the patients.