Acute Effects of Inspiratory Muscle Training on Pulmonary Arterial Pressure,Cardiac Output and Pulmonary Arterial Saturation Derived Oxygen Cost of Breathing

Sven Stieglitz,Christina Priegnitz,Winfried Randerath,Lars Hagmeyer,Sandhya Matthes

doi:10.21767/2572-5548.100023

Abstract

Respiration and respiratory maneuvers affect cardiac output. Inspiratory muscle training (IMT) increases the negative thoracic pressure, which could have an impact on intra-thoracic hemodynamics and thereby influence the cardiac output (CO). The objective of our study was to determine changes in pulmonary arterial (PA) hemodynamics and the CO during IMT in patients with suspected pulmonary hypertension. A new method for measuring the oxygen cost of breathing during IMT was also developed. 22 patients were included in this prospective study. They performed IMT during right heart catheterization. Mixed-venous blood gas analysis was performed before and at the end of IMT to calculate the oxygen cost of breathing. The baseline PA pressure was systolic/diastolic/mean (s/d/m) 41 ± 20/13 ± 20/25 ± 11 mmHg. The CO was 5.3 ± 1.5 l/min. The IMT was set to 2.3 ± 0.6 kPa (23.7 ± 5.7 cmH2O). The PA pressure at the end of IMT was s/d/m 44/10/22 mmHg s/d/m. Though there was a trend towards a lower diastolic pressure, this change was not statistically significant (p=0.06). CO (6.2 ± 1.1 l/min) did not change due to IMT. The mixed-venous hemoglobin oxygen saturation was 71.8 ± 2.3% before IMT, with a significant reduction to 65.8 ± 5.9% (p=0.027) at the end of IMT. IMT as performed in our study neither changed the mean PA pressure nor the CO. Measuring the oxygen cost of breathing is feasible by the method described in our paper.

Highlights

pulmonary hypertension (PH) is common in patients with reduced After measurement of the hemodynamic parameters (by ejection fraction (EF) and in those with elevated left Ultraview SL, Spacelabs, Snoqualmie, Washington, USA) and ventricular filling pressures, which can lead to PH assessment of the blood samples, patients were switched to a independently of the ejection fraction [16,17]
The median mean pulmonary artery pressure (mPAP) in the study population was not elevated above ≥ 25 mmHg, so a pulmonary arterial hypertension was excluded
In our study we did not observe any change of cardiac output (CO) that might explain at least in part why the mPAP did not change at the end of the Inspiratory muscle training (IMT) trial

Summary

Introduction

During inspiration usually right ventricular stroke volume is reported in studies is between 25-100%) of the exact incidence of PH in patients with cardiac disease are not available [15]. PH is common in patients with reduced After measurement of the hemodynamic parameters (by ejection fraction (EF) and in those with elevated left Ultraview SL, Spacelabs, Snoqualmie, Washington, USA) and ventricular filling pressures, which can lead to PH assessment of the blood samples, patients were switched to a independently of the ejection fraction [16,17]. The Threshold-IMT incorporates a flowin PH due to left heart disease [18,19]. It was shown independent one-way valve to ensure a constant resistance. During IMT (exactly 2 min after assessed during right heart catheterization were not correlated initiation of the IMT) PAP and CO were measured and a blood with 6MWD) [21]

Objectives

Methods

Results

Conclusion