Abstract
For the non-invasive assessment of pulmonary artery pressure (PAP), surrogates like pulse wave transit time (PWTT) have been proposed. The aim of this study was to invasively validate for which kind of PAP (systolic, mean, or diastolic) PWTT is the best surrogate parameter. To assess both PWTT and PAP in six healthy pigs, two pulmonary artery Mikro-Tip™ catheters were inserted into the pulmonary vasculature at a fixed distance: one in the pulmonary artery trunk, and a second one in a distal segment of the pulmonary artery. PAP was raised using the thromboxane A2 analogue U46619 (TXA) and by hypoxic vasoconstriction. There was a negative linear correlation between PWTT and systolic PAP (r = 0.742), mean PAP (r = 0.712) and diastolic PAP (r = 0.609) under TXA. During hypoxic vasoconstriction, the correlation coefficients for systolic, mean, and diastolic PAP were consistently higher than for TXA-induced pulmonary hypertension (r = 0.809, 0.778 and 0.734, respectively). Estimation of sPAP, mPAP, and dPAP using PWTT is feasible, nevertheless slightly better correlation coefficients were detected for sPAP compared to dPAP. In this study we establish the physiological basis for future methods to obtain PAP by non-invasively measured PWTT.
Highlights
Pulmonary hypertension (PH) is defined as a mean pulmonary artery pressure above 25 mmHg measured by right heart catheterisation at rest [1]
During induction of pulmonary hypertension (PH) and mechanical ventilation, pulse wave transit time (PWTT) showed a good linear correlation with systolic PAP (sPAP), mean pulmonary artery pressure (mPAP) and dPAP, which was slightly better during hypoxia
Even though our study presents a strong correlation of PWTT with sPAP, mPAP and dPAP as measured by the gold standard of pulmonary artery catheterisation, this experiment has clear limitations
Summary
Pulmonary hypertension (PH) is defined as a mean pulmonary artery pressure (mPAP) above 25 mmHg measured by right heart catheterisation at rest [1]. Untreated PH will lead to right heart, and to global heart failure, and is associated with a high mortality within one year [1]. Treatment requires reliable measurement and monitoring of pulmonary artery pressure (PAP). Diagnosis of PH is based on right heart catheterisation, but this comprises high invasiveness. Current non-invasive methods like echocardiography or magnetic resonance imaging (MRI). Are not accurate enough to confirm the diagnosis of PH or serve as follow-up [1,2,3]. It would be desirable to develop novel techniques for diagnosis and longitudinal monitoring of PH
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