(One interesting study to be aware of in relation to Pulmonary Artery Catheter's hemodynamic monitoring) 

Diastolic Pulmonary Vascular Pressure Gradient: A Predictor of Prognosis in “Out-of-Proportion” Pulmonary Hypertension (1)

Background: Left-sided heart disease (LHD) is the most common cause of pulmonary hypertension (PH). In patients with LHD, elevated left atrial pressure causes a passive increase in pulmonary vascular pressure by hydrostatic transmission. In some patients, an active component caused by pulmonary arterial vasoconstriction and/or vascular remodeling superimposed on left-sided pressure elevation is observed. This “reactive” or “out-of-proportion” PH, defined as PH due to LHD with a transpulmonary gradient (TPG) > 12 mm Hg, confers a worse prognosis. However, TPG is sensitive to changes in cardiac output and left atrial pressure. Therefore, we tested the prognostic value of diastolic pulmonary vascular pressure gradient (DPG) (ie, the difference between invasive diastolic pulmonary artery pressure and mean pulmonary capillary wedge pressure) to better prognosticate death in “out-of-proportion” PH.

Methods: A large database of consecutive cases was analyzed. One thousand ninety-four of 2,351 complete data sets were from patients with PH due to LHD. For proof of concept, available lung histologies were reviewed.

Results: In patients with postcapillary PH and a TPG > 12 mm Hg, a worse median survival (78 months) was associated with a DPG ≥ 7 mm Hg compared with a DPG < 7 mm Hg (101 months, P = .010). Elevated DPG was associated with more advanced pulmonary vascular remodeling.

Conclusions: DPG identifies patients with “out-of-proportion” PH who have significant pulmonary vascular disease and increased mortality. We propose a diagnostic algorithm, using pulmonary capillary wedge pressure, TPG, and DPG in sequence to diagnose pulmonary vascular disease superimposed on left-sided pressure elevation.



References and further reading:

1. Christian Gerges; Mario Gerges, MD; Marie B. Lang; Yuhui Zhang, MD; Johannes Jakowitsch, PhD; Peter Probst, MD; Gerald Maurer, MD; Irene M. Lang, MD - Diastolic Pulmonary Vascular Pressure Gradient: A Predictor of Prognosis in “Out-of-Proportion” Pulmonary Hypertension  Chest. 2013;143(3):758-766. doi:10.1378/chest.12-1653 

2. Pulmonary hypertension in sepsis: Measurement by the pulmonary arterial Diastolic-pulmonary wedge pressure gradient and the influence of passive and active factors. Chest 1978; 73:583-91 

3. Significance of the pulmonary artery diastolic-pulmonary wedge pressure gradient in sepsis. Crit Care Med 1982; 10:658-61 

4. Pulmonary artery diastolic and wedge pressure relationships in critically and injured patients. Arch Surg 1988; 123:933-6 

5. Increased Pulmonary Venous Resistance Contributes to Increased Pulmonary Artery Diastolic-Pulmonary Wedge Pressure Gradient in Acute Respiratory Distress Syndrome - Anesthesiology: Volume 102(3) March 2005 pp 574-580