Clinical application of a digital thoracic drainage system for objectifying and quantifying air leak versus the traditional vacuum system: a retrospective observational study

Abstract

Background: Digital thoracic drainage systems have recently been introduced and widely used in clinical practices in developed countries. These systems can monitor intrathoracic pressure changes and air leaks in real time, and also allow for objective and quantitative analyses, which aid in managing patients with a prolonged persistent air leak into the pleural space. We investigated the feasibility and effectiveness of such a new device versus the traditional vacuum system for treating patients with pneumothorax.

Methods: Closed thoracostomy drainage was carried out on 100 adult patients with primary or secondary pneumothorax between January 2017 and December 2018. All the patients were aged ≥18 years and treated with a chest tube at a single medical center by the same cardiothoracic surgeons and intensivists. Patients who underwent closed thoracostomy drainage using an indwelling 24-French chest tube were divided into 2 groups immediately before closed thoracostomy: the digital thoracic drainage group (digital group, n=50) and the traditional analogue thoracic drainage group (analogue group, n=50). The detailed information about demographic data, treatment outcome, duration of indwelling catheterization., hospital days, cost-effectiveness and patient satisfaction was evaluated. We also evaluated whether digitally recorded intrapleural pressure changes and air leaks would predict chest tube removal timing and outcome.

Results: The baseline parameters of the 2 groups were comparable with no significant differences in sex, age, weight or body mass index. The mean hospital day was shorter in the digital group than in the analogue group (17.96±12.23 vs. 18.32±16.64, P=0.902), and there was no statistically significant difference in the hospital length of stay between the 2 groups. Air leaks through the chest tube and duration of chest tube indwelling hours showed no significant statistical differences between the digital and analogue groups (213.47±219.80 vs. 261.94±184.47, P=0.235 and 223.44±218.75 vs 275.29±186.06, P=0.205, respectively). Total drainage amount and ambulation time per day were significantly higher in the digital group than in the analogue group [209.62±139.63 vs. 162.48±80.42 (P=0.042) and 6.42±3.62 vs.3.94±1.74 (P<0.001), respectively]. Hours of full expansion were significantly shorter and sleep disturbance caused by the noise of chest tube drainage was less in the digital group than in the analogue group [25.64±14.55 vs. 46.52±25.53 (P<0.001) and 2.38±1.03 vs. 5.70±2.87 (P<0.001), respectively].

Conclusions: To date, there is no definite consensus and guidelines on the standardized digital suction system in pneumothorax. This study proposed the guidelines for the application of digital thoracic drainage systems in pneumothorax and also suggested that digital thoracic drainage systems might be a valuable tool to determine chest tube removal timing and reducing the length of hospital stay in patients with pneumothorax.

Keywords: Thoracostomy; analogue; chest tubes; digital; drainage; pneumothorax; suction.

Conflict of interest statement

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/jtd-20-2993). The authors have no conflicts of interest to declare.

2021 Journal of Thoracic Disease. All rights reserved.

Figures

Figure 1

Comparison between the digital and analogue groups. The columns and dots show group mean values with standard error bars. More detailed data are summarized in Tables 1 and 2. (A) Ambulation time each day (hours): AMD =2.48; SD=2.83; SE=0.56; P<0.0001. (B) Time to full expansion (hours): AMD =20.87; SD=20.77; SE=4.15; P<0.0001. (C) Total drainage amount (ml): AMD =47.14; SD=113.93; SE=22.78; P=0.0412. (D) Sleep disturbance by CTD noise: AMD =3.31; SD=2.15; SE=0.43; P<0.0001. (E) Time to air leakage via CTD (hours): AMD =48.46; SD=205.96; SE=40.58; P=0.2352. (F) Time for indwelling CTD (hours): AMD =51.85; SD=203.06; SE=40.61; P=0.2047. (G) Hospital day (days): AMD =0.36; SD=14.60; SE=2.92; P=0.9022. (H) Pneumothorax size (%): AMD =3.55; SD=25.24; SE=5.04; P=0.4831. AMD, arithmetic mean difference; SD, standard deviation; SE, standard error; P, statistical probability; CTD, closed thoracostomy drainage.

Figure 2

(A) Representative data from the digital suction device. This figure shows target vacuum (mbar), measured vacuum (mbar) and flow (mL/min), based on data extracted from a case of a 17-year-old male patient with spontaneous pneumothorax who was treated only with closed thoracostomy drainage using a digital suction device without any surgical approaches. (B) Measured vacuum depicted in the same patient data. The fluctuations in vacuum were diminished and stabilized at the end of the ninth hospital day. This implies that the air leakage is completely ceased, indicating the optimal timing of chest tube removal.

Figure 3

Histogram of pressure gradients through the chest tube. This figure shows pressure variations through the chest tube, based on data extracted from a case of a 67-year-old male patient with secondary pneumothorax who was treated only with closed thoracostomy drainage using a digital suction device without any surgical approaches. The pressure gradients were automatically checked every 6 seconds and saved at the server of the device. The saved data were easily identified through the integral on-board screen of the digital suction device and were efficiently extracted using a universal serial bus flash memory. The black dotted line indicates the trend of pressure gradients through the chest tube per hospital day (y =−0.0086x +25.077, R2 =0.04427). Note that the pressure gradient sharply decreased approximately on the 11th hospital day, which indicates a reduction of mechanical demand on suction power for equilibrium. Clinically, it represents a decrease in pressure for the proper maintenance of intrathoracic pressure and means a reduction of air leakage from the injured pneumothorax lung. This figure was reconstructed and completed using Microsoft Excel (Microsoft, Redmond, WA, USA) on the basis of data from the digital suction device.

Figure 4

Comparison of view between the digital (A) and analogue (B) suction devices in the real clinical setting. The digital system uses a double-lumen hose system, which consists of a measuring/rinsing hose as well as a secretion hose. Black arrows indicate a measuring/rinsing hose with an integrated hydrophobic bacterial filter, which prevents bacteria from entering the device. Black arrowheads indicate a secretion hose, through which secretions and air are suctioned and collected in a fully transparent secretion canister. The digital system has an automatic hose rinsing function, working periodically, 2 rinsing cycles every 3 minutes. The rinsing process transports secretions in the secretion hose to the secretion canister, which prevents accumulation of debris in the secretion hose, ingress of secretions into the measuring/rinsing hose, and creation of syphon effect. The automatic hose rinsing function enables sufficient drainage without milking and/or squeezing. The analogue suction device comprises 2 bottles, water sealed and suction control bottles. It has a thick yellowish rubber which is connected to the chest drainage tube for milking and/or squeezing and is mounted to the wall suction (empty arrowhead with black outline). The empty arrow with black outline indicates the tube connecting to the patient’s chest tube in (A) and (B).