PURPOSE: Pleural effusions are common with a wide variety of causes. It has been shown in several studies that characterizing the pleural elastance provides diagnostic information and aides in therapeutic decisions (1,4,10,11,12).
METHODS: This is a retrospective review of pleural manometry data collected from 67 thorocentesis performed at the Veterans Affairs Medical Center, Washington DC.
RESULTS: Data from 67 thorocentesis was included for analysis. The causes of pleural effusion were attributed to malignancy (23), parapneumonic (14), CHF (12), uremia (6), hypoproteinemia (2), hemothoroax (2), reactive (1) and undetermined (7). There were 42 exudative, 24 transudative and 1 unknown. Based on the shape of the elastance curve, example shown in Graph 1, patients were classified as having normal (38), entrapped (25), or trapped (4) lung. The mean elastance for normal, entrapped, and trapped group was 11.96 cmH20/L [95% CI 12.60, 11.3], 34.67 cmH20/L [95% CI 35.55, 33.78], 271.95 cmH20/L [95%CI 116.61, 427.29], respectively [P= <0.0000001]. There was no statistically significant difference in the opening pressure between the groups. The mean closing pressure for the normal, entrapped, and trapped group was -7.5 cmH20 [95% CI -11.8, 3.18], -32.54 cmH20 [95% CI -40.9, 24.18], -62.57 cmH20 [95% CI -32.11, - 93.03], respectively. There was a statistically significant difference between the mean closing pressure of the normal and entrapped groups with a P= < 0.0000001 and also between the mean closing pressure of the entrapped and trapped groups with P= <0.013.
CONCLUSION: We conclude that pleural manometry in our sample of patients clearly helped distinguish a normal, entrapped, and trapped lung based on the shape of the curve. There was a statistically significant difference in mean elastance, and mean closing pressure between the three groups.
CLINICAL IMPLICATIONS: Routine use of pleural manometry in patients with pleural effusions will help physicians better characterize effusions and make theraputic decisions.
DISCLOSURE: Cara Kistler, No Financial Disclosure Information; No Product/Research Disclosure Information