Time course of thoracocentesis-induced alterations in lung function parameters

We evaluated changes in lung function parameters induced by thoracocentesis (TS), before,30 minutes and 48 hrs. after removal of varying amounts of pleural fluid in 90 patients with unilateral pleural effusion (58 male and 32 female, aged 61.6 ± 15.9 yrs., by obtaining their spirometric data, just before (T1), 30 minutes after (T2) and 48 hrs. (T3), after TS. Patients were separated in two groups according to the initial size of the effusion: Group A with small & moderate effusions (52 pts.) and Group B with large & massive effusions (38 pts.). Spirometry was performed by an electronic spirometer recording Forced Vital Capacity (FVC), Forced Expiratory Volume in 1 second (FEV1), FEV1/FVC ratio and Peak Expiratory Flow Rate (PEFR). in Group A, a mean volume of 716.9±562.2 ml was removed resulting in an increase in FVC of 71ml (p=0.027), of FEV1 in 127ml (p<0.001), of FEV1/FVC in 3% (p<0.001), of PEFR of 21 l/min.(p<0.001).In Group B a mean volume of 1015±413.5 ml was removed resulting in an increase in FVC of 139 ml (P<0.001), of FEV1 in 201 ml (p<0.001), FEV1/FVC in 5% (p<0.001), PEFR in 23 l/min (p<0.001). From T2 to T3, in Group A there was a further increase in FVC by 97ml (p=0.027), in FEV1 by 38.9 ml (p<0.001), in FEV1/FVC a decrease by 1.7% (p,0.001) an increase in PEFR by 47 l/min,(p< 0.001). In Group B, FVC increased by 104 ml (p=0.01), FEV1 decreased by 8 ml (p=0.024), FEV1/FVC decreased by 7% (p=0.05), PEFR increased by 10.4 l/min (p=0.06). FVC, FEV1 & PEFR although increase signifigantly at T1 & and further at T2, these changes were disproportionately small compared to the amount of fluid removed, while regarding the FEV1/FVC, an increased ratio emerged at T2 but was restored at T3.