Intrapleural pressure measurements and respiratory function tests (including diffusion test, body plethysmography) measurements in the detection of the presence of trapped lung (trapped / entrapped lung) in patients with pleural fluid

Our study is a prospective study in which patients with unilateral pleural effusion. To investigate the guiding parameters in detecting the presence of trapped lung in patients with pleural fluid, patients whose fluid was drained by thoracentesis were included in the evaluation. The values obtained by body plethysmography before and after the fluid discharge process and intrapleural pressure measurements measured at the beginning of the procedure and after fluid drained (500 ml and 1000 ml) were recorded. These values were +4.58 cm H2O in those with trapped lung at baseline and +4.70 cm H2O in those without (p=0.034). After 500 ml fluid evacuation, it was -4.12 cm H2O in those with trap lungs, +0.60 cm H2O in those without (p=0.003), and after 1000 ml fluid evacuation, it was -7.20 cm H2O in those with trap lungs and -3.23 cm H2O in those without (p=0.039). In pleural space elastance calculations, after 500 ml fluid drain, 17.7179 cm H2O/L was calculated in those with non-expandable lungs and 8.4500 cm H2O/L in those without (p=0.000). These values were 12.5968 cm H2O/L in those with non-expandable lungs and 7.9118 cm H2O/L in those without (p=0.009) after 1000 ml fluid drain. The FEV1 value measured after the pleural fluid was drained was 0.8895 in those with trapped lungs and 1.1695 in those without (p=0.030). The FVC value was 1.0528 in those with non-expandable lung and 1.4078 in those without (p=0.022). The average pH was 7.31 in 37 patients with non-expandable lung, and the average pH was 7.34 in 39 patients without non-expandable lung (p=0.530). With the current findings, we found that elastance measurements are useful in detecting the presence of a non-expandable lung before therapeutic thoracentesis. However, we did not find a relationship between airway resistance and vital capacity and the presence of a non-expandable lung. Key Words: Pleural fluid, intrapleural pressure, pleural manometry, elastance, body plethysmography, non-expandable lung