Search

Background Inconsistent and contradictory findings have appeared in the literature concerning the impact of body position on oxygenation in pleural effusion. Methods We attempted to elucidate whether the size of the pleural effusion in patients with no parenchymal disease is the main determinant of posture-induced alterations in oxygenation parameters. We studied 62 spontaneously breathing patients aged 65.3±7.8 years (mean±SD), of whom 36 had large and massive-sized effusions (Group A) and 26 had small and moderate-sized effusions (Group B). Arterial blood gases were determined in four different body positions: sitting (SIT), supine (SUP), ipsilateral (IPS) and contralateral (CON) to the effusion side, after remaining relaxed for at least 20 min in each position. Separation into groups A and B was deliberately set from the position of the fluid meniscus line on a posteroanterior chest film just above the upper costal margin of the sixth anterior rib. A two-way ANOVA model with outcome variables PaO2, PaCO2 and [A–a] DO2 was used. Results In both groups the best oxygenation was found in SIT. The worst oxygenation (highest [A–a] DO2 value) occurred in group A in CON compared with IPS (59.4±7.6 vs 49.0±7.5 mm Hg, p Conclusions Patients with large-sized effusions exhibit the worst oxygenation when lying on the side contralateral to the effusion, while those with small-sized effusions exhibit the worst oxygenation when lying on the side ipsilateral to the effusion.

Background Several studies investigated the effects of thoracocentesis on aspects of respiratory function without generally ensuring absence of coexistent lung pathology or homogeneity in initial size of the effusion. Methods We studied 90 patients aged 61.6±15.9 years (mean±SD) separated into a group A with small-sized or medium-sized effusion (A=56 patients) and a group B with large and massive one (B=34 patients). There was no significant lung lesion or cardiovascular pathology. The basic spirometric parameters and maximal respiratory pressures were recorded on three instances: just before thoracocentesis (T1), 30 min after completion of the procedure (T2) and after 48 hours (T3). Results At T2 vs T1, groups A and B respectively presented significant change (mean±SD) (increase) in forced vital capacity (FVC) of 0.071±0.232 and 0.139±0.224 L, in forced expiratory volume in 1 s (FEV1) of 0.127±0.231 and 0.201±0.192 L, in FEV1/FVC of 2.8% and 4.9%, in peak expiratory flow rate (PEFR) of 0.342±0.482 and 0.383±0.425 L/s, in maximal expiratory pressure (MEP) of 0.049±0.037 and 0.049±0.039 kPa and in maximal inspiratory pressure (MIP) of 0.040±0.041 kPa only in group A while decrease in MIP with significant change of 0.055±0.051 kPa in group B. At T3 vs T2 in groups A and B, there was significant change (decrease) in FEV1/FVC of 2.7% and 4.6% as well as significant change (increase) in MIP of 0.036±0.046 and 0.115±0.060 and in MEP of 0.049±0.043 and 0.070±0.048 kPa. Conclusions Thoracocentesis is associated with progressive-small relative to the volume of fluid removed-increases in lung volumes. In larger effusions at T2, a transient decrease in MIP is observed presumably due to temporary geometric distortion of the diaphragm immediately after fluid removal.

Background There have been contradicting reports in the literature regarding the impact of pleural fluid aspiration on patients’ oxygenation. The aim of this study was to assess the role of the initial size of effusion on post-drainage oxygenation. Methods We studied 122 patients, aged (mean±SD) 61.2±16.8 years, with unilateral pleural effusion and no remarkable parenchymal lesion, by determining PaO2, PaCO2 and [A−a] PaO2 just before thoracocentesis (T1), 30 min after its completion (T2) and 48 hours after the procedure (T3). Patients were divided into group A (75 patients) with small and moderate sized effusions and group B (47 patients) with large and massive effusions. The position of the meniscus line on the posteroanterior film, being arbitrarily set at just above the upper costal margin of the sixth anterior rib, was used to divide the two groups. Patients were studied at rest, breathing room air in the sitting position. Repeated measures ANOVA (related samples) and the Friedman test when the normality assumption was violated were used. Results In group A, at T3, PaO2(mm Hg) showed a statistically significant increase versus T1 (p Conclusion Patients with smaller effusions showed a small improvement in their oxygenation 48 hours post-thoracocentesis (T3). Patients with larger effusions exhibited a transient reduction in their oxygenation immediately after fluid removal (T2).