Early Effects of Oxygen Administration and Prognosis in Chronic Obstuctive Pulmonary Disease and Cor Pulmonale^1–3

Abstract

The purpose of this study was to develop criteria for predicting survival and clinical improvement with long-term domiciliary home oxygen therapy (LTDO2) in patients with both chronic obstructive pulmonary disease (COPD) and cor pulmonale (CP). Twenty-eight such patients were divided into 2 groups, responders (R) and nonresponders (NR), on the basis of the fall in their mean pulmonary artery pressure (delta PAP) while breathing 28% O2 for 24 h. The R(n = 17) and NR (n = 11) had delta PAP greater than and lesser than 5 mmHg, respectively. Eighty-eight percent of the R, but only 22% of the NR, were alive at the end of 2 yr of LTDO2. Eighty-five percent of R, but only 11% of NR, achieved an end-exercise maximal oxygen consumption (max VO2) greater than 6.5 ml min-1 kg-1. Left ventricular ejection fraction improved while breathing O2 for 48 h in the R only. The NR and R were similar in all other respects. We conclude that delta PAP greater than 5 mmHg and/or max VO2 6.5 ml min-1 kg-1 or greater predict 2-yr survival with LTDO2 in patients with COPD and CP, and it can be useful in planning their management.

Pulmonary hypertension in chronic obstructive pulmonary disease

“…First, studies performed in COPD patients have shown not only a wide variation in the individual responses of the pulmonary circulation to changes in inspired oxygen concentration [14,33,34], but also a low correlation between Pa,O 2 and Ppa [7]. Second, LTOT does not reverse pulmonary hypertension, although it prevents its progression [35].…”

“…At this stage, the reactivity of pulmonary arteries to hypoxia might also be altered in some patients with mild COPD [16,34,41], hence contributing to alveolar ventilation/perfusion ratio (V9A/Q9) mismatching and promoting the development of arterial hypoxaemia. In this scenario, sustained exposure to hypoxaemia may induce further pulmonary vascular remodelling thus amplifying the initial effects of cigarette-smoke products ( fig.…”

“…Considering that the haemodynamic response to oxygen administration might be widely variable in COPD, ASHUTOSH et al [34] evaluated the long-term effects of oxygen therapy according to its acute effects on pulmonary haemodynamics. These authors showed that survival benefit of LTOT was greater in patients who showed a significant decrease in Ppa during the acute administration of oxygen (acute responders) [34].…”

Pulmonary Hypertension in Patients with Chronic Obstructive Pulmonary Disease: A Review for Definition, Epidemiology, Pathology, and Diagnosis

“…Findings supporting this circumstance can be listed as follows: 1) non-normalization of PAP with oxygen therapy [51] and variability of the hemodynamic response to oxygen therapy [52], 2) the relationship between PAP and oxygen partial pressure (PaO 2 ) is not strong and cannot always be shown [3,10]) changes in pulmonary vasculature and detection of endothelial dysfunction in non-hypoxic mild COPDs [39,53,54] and 4) observation of PAP increase in animal models exposed to cigarette smoke before COPD [55]. As a result, hypoxia plays a key role in the development of PHT in this patient group, but it cannot be held responsible alone for all hemodynamic changes.…”

“…These changes in intrathoracic pressure cause lowered cardiac output due to decreased systemic venous return or increase in afterload [28]. Therefore, in advanced COPD patients with mild PHT (25-30 mmHg) at rest, there is a significant increase in PAP (50)(51)(52)(53)(54)(55)(56)(57)(58)(59)(60) with an increase in cardiac output after constant moderate level exercise. When clinically assessed, an exercise at this level can coincide with daily activities, and therefore, significant PHT can develop in daily activities [31].…”