Functions and Control of the Pulmonary Circulation

Mazza, Emílio; Taichman, Darren B.

doi:10.1016/b978-1-4160-2246-6.50007-9

Cited by 4 publications

(5 citation statements)

References 120 publications

(120 reference statements)

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“…Cardiac output (CO) was calculated by the Fick equation: CO = (oxygen consumption)/(arterial oxygen saturation − mixed venous oxygen saturation) using standardised reference tables to estimate oxygen consumption 13. PVR was calculated using the formula: PVR = (mPAP − mLAP)/CO,14 where mLAP = mean left atrial pressure. Left ventricular end diastolic pressure was used to estimate mLAP in patients with simultaneous left heart catheterisation (n = 51).…”

Section: Methodsmentioning

confidence: 99%

Pulmonary vascular resistance predicts early mortality in patients with diffuse fibrotic lung disease and suspected pulmonary hypertension

Corte

Wort

Gatzoulis

et al. 2009

Thorax

109

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Background: Pulmonary hypertension (PH) is associated with a poor prognosis in diffuse lung disease (DLD). A study was undertaken to compare the prognostic significance of invasive and non-invasive parameters in patients with DLD and suspected PH. Methods: Hospital records of consecutive patients with DLD undergoing right heart catheterisation (RHC) were reviewed (n = 66). Mean pulmonary artery pressure (mPAP), pulmonary vascular resistance (PVR) and noninvasive variables were examined against early (within 12 months) and overall mortality. A priori thresholds were examined against early mortality. Relationships between mPAP, PVR and non-invasive markers were assessed. Results: Fifty patients had PH on RHC (mean (SD) mPAP 33.5 (11.8) mm Hg, PVR 5.9 (4.3) Wood units (WU)). Raised PVR was strongly associated with early mortality (odds ratio (OR) 1.30; 95% confidence interval (CI) 1.11 to 1.52; p = 0.001), with PVR >6.23 WU being the optimal threshold after adjustment for age, gender, composite physiological index (CPI) and diagnosis of idiopathic pulmonary fibrosis (OR 11.09; 95% CI 2.54 to 48.36; p = 0.001). Early mortality was linked, albeit less strongly, to right ventricular dilation at echocardiography, but not to other non-invasive variables or mPAP. Overall mortality was most strongly associated with increasing CPI levels. Correlations between PVR and non-invasive variables were moderate (R 2 ,0.32), improving little following construction of a multivariate index which did not itself predict mortality. Conclusion: In severe DLD, early mortality is strongly linked to increased PVR but not to other RHC or noninvasive variables. These findings suggest that the threshold for RHC in severe DLD should be low, enabling prioritisation of aggressive treatment including lung transplantation.

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Section: Methodsmentioning

confidence: 99%

Pulmonary vascular resistance predicts early mortality in patients with diffuse fibrotic lung disease and suspected pulmonary hypertension

Corte

Wort

Gatzoulis

et al. 2009

Thorax

109

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“…Cardiac output was calculated by using the Fick equation (14). The pulmonary vascular resistance index (PVRi) was calculated by using the following formula: PVRi ϭ (mPAP Ϫ mLAP)/Qi, where mLAP is the mean left atrial pressure and Qi is the cardiac index calculated by dividing the cardiac output by the body surface area (15). Body surface area was calculated by using the following equation: BSA ϭ 0.20247 ϫ H 0.725 ϫ W 0.425 , where BSA is body surface area measured in square meters, H is height measured in meters, and W is weight measured in kilograms (16).…”

Section: Right Heart Catheterizationmentioning

confidence: 99%

The Effect of Diffuse Pulmonary Fibrosis on the Reliability of CT Signs of Pulmonary Hypertension

Devaraj

Wells²,

Meister³

et al. 2008

Radiology

140

102

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“…Since the PVR is held constant as an independent variable in our models, the pulmonary arterial pressure is linearly proportional to the pulmonary flow rate, thus creating a linear relationship between the nozzle area and the pulmonary arterial pressure. In practice, the pulmonary arterial pressure might plateau when the nozzle area increases beyond a certain value since studies show that the PVR drops as the pulmonary arterial pressure increases [48,49]. As expected, the rate at which the pulmonary arterial pressure increases with the nozzle area, as well as its absolute value, increases with the PVR.…”

Section: Cfd and Algebraic Model Comparisonmentioning

confidence: 52%

“…One limitation of our algebraic model is the assumption of a constant PVR. As we discussed in this paper, the PVR changes as a function of the pulmonary arterial pressure and the pulmonary oxygen saturation [48,49]. Such dynamic response is therefore missing in the algebraic model.…”

Section: Discussionmentioning

confidence: 96%

“…If we consider that pressure to be the maximum allowable SVC pressure, then a patient receiving a 2 mm 2 nozzle should remain in the safe zone as long as the PVR remains below 7 Wood units-m 2 . Moreover, studies showed that the PVR value generally decreases as the oxygen saturation and the pulmonary arterial pressure are increased [48,49]. For its higher saturation and PA pressure, the ABG operation patients are expected to have a lower PVR than those undergoing the mBTS or BDG.…”

Section: Discussionmentioning

confidence: 99%

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Characterization of the Ejector Pump Performance for the Assisted Bidirectional Glenn Procedure

Jia

Esmaily

2022

Fluids

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This study introduces an algebraic model informed by computational fluid dynamics (CFD) simulations to investigate the performance of the assisted bidirectional Glenn (ABG) operation on a broad range of conditions. The performance of this operation, as measured by the superior vena cava (SVC) pressure, depends on the nozzle area in its ejector pump and the patient’s pulmonary vascular resistance (PVR). Using the developed algebraic model to explore this two-dimensional parameter space shows that the ejector pump can create a pressure difference between the pulmonary artery and the SVC as high as 5 mmHg. The lowest SVC pressure is produced at a nozzle area that decreases linearly with the PVR such that, at PVR =4.2 (Wood units-m2), there is no added benefit in utilizing the ejector pump effect (optimal nozzle area is zero, corresponding to the bidirectional Glenn circulation). At PVR =2 (Wood units-m2), the SVC pressure can be lowered to less than 4 mmHg by using an optimal nozzle area of ≈2.5 mm2. Regardless of the PVR, adding a 2 mm2 nozzle to the baseline bidirectional Glenn boosts the oxygen saturation and delivery by at least 15%. The SVC pressure for that 2 mm2 nozzle remains below 14 mmHg for all PVRs less than 7 Wood units-m2. The mechanical efficiency of the optimal designs consistently remains below 30%, indicating the potential for improvement in the future. A good agreement is observed between the algebraic model and high-fidelity CFD simulations.

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Functions and Control of the Pulmonary Circulation

Cited by 4 publications

References 120 publications

Pulmonary vascular resistance predicts early mortality in patients with diffuse fibrotic lung disease and suspected pulmonary hypertension

Pulmonary vascular resistance predicts early mortality in patients with diffuse fibrotic lung disease and suspected pulmonary hypertension

The Effect of Diffuse Pulmonary Fibrosis on the Reliability of CT Signs of Pulmonary Hypertension

Characterization of the Ejector Pump Performance for the Assisted Bidirectional Glenn Procedure

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