Low protein content of drainage fluid is a good predictor for earlier chest tube removal after lobectomy.

OBJECTIVES: Owing to the great absorption capability of the pleura for transudates, the protein content of draining pleural fluid may be considered as a more adequate determinant than its daily draining amount in the decision-making for earlier chest tube removal. In an a priori pilot study, we observed that the initially draining protein-rich exudate converts to a transudate quickly in most patients after lobectomies. Thus, chest tubes draining high-volume but low-protein fluids can safely be removed earlier in the absence of an air leak. This randomized study aims to investigate the validity and clinical applicability of this hypothesis as well as its influence on the timing for chest tube removal and earlier discharge after lobectomy.

METHODS: Seventy-two consecutive patients undergoing straightforward lobectomy were randomized into two groups. Patients with conditions affecting postoperative drainage and with persisting air leaks beyond the third postoperative day were excluded. Drains were removed if the pleural fluid to blood protein ratio (PrRPl/B) was ≤0.5, regardless of its daily draining amount in the study arm (Group S; n = 38), and patients in the control arm (Group C; n = 34) had their tubes removed if daily drainage was ≤250 ml regardless of its protein content. Patients were discharged home immediately or the following morning after removal of the last drain. All cases were followed up regarding the development of symptomatic pleural effusions and hospital readmissions for a redrainage procedure.

RESULTS: Demographic and clinical characteristics as well as the pattern of decrease in PrRPl/B were the same between groups. The mean PrRPl/B was 0.65 and 0.67 (95% CI = 0.60-0.69 and 0.62-0.72) on the first postoperative day, and it remarkably dropped down to 0.39 and 0.33 (95% CI = 0.33-0.45 and 0.27-0.39) on the second day in Groups S and C, respectively, and remained below 0.5 on the third day (repeated-measures of ANOVA design, post hoc 'within-group' comparison of the first postoperative day versus second and third days; P < 0.002). Eleven of 38 (29%) and 16 of 27 (59%) patients' chest tubes were, respectively, removed on the first and second postoperative days in Group S, but only two of 34 (6%) and ten of 32 (31%) patients, respectively, had their chest tubes removed in Group C (two-tailed Fisher's exact test, P = 0.02 and 0.005 for the first and the second postoperative days, respectively). On the third postoperative day, daily drainage remained ≥250 ml in 22 (65%) patients, among whom, 17 (77%) would have their chest tubes removed on the PrRPl/B value in Group C. However, drains could not be removed due to the high protein content of draining fluid despite the acceptable volume of daily drainage in only three (27%) of 11 cases in Group S (McNemar's paired proportions test, P = 0.009). The mean chest tube removal time (2.1 ± 0.9 vs 2.9 ± 1.0 days; P < 0.001) and the median hospital stay [3 days (IQR: 1-3) vs 4 days (IQR: 2-4), P < 0.003] were significantly shorter in Group S. None of the patients required a redrainage procedure due to a persistent and symptomatic pleural effusion.

CONCLUSIONS: Regardless of the daily drainage, chest tubes can safely be removed earlier than anticipated in most patients after lobectomy if the protein content of the draining fluid is low.