Introduction
From the anatomical point of view, the pleural space is limited by the visceral pleura, which covers the entire surface of the lung, and the parietal pleura, which covers the inner surface of the ribs, pericardium, and diaphragm. The parietal pleura has a rich network of lymphatic vessels with direct connection to the pleural space. The lymphatic network of the visceral pleura does not have a direct direction to the pleural space; as a result, its role is liquid absorption [1]. The pleural fluid is hypo-oncotic, which explains the low permeability of the parietal pleura to water and protein. When pleural lymphatic drainage is insufficient, pleural fluid accumulates and leads to pulmonary collapse. Therefore, complete evacuation of air and fluid after thoracic surgery is of great importance [2].
Today, many patients with pleural effusion due to various causes such as trauma, malignancy, failure of internal organs, infection, inflammation, etc., refer to different departments of hospitals, and these patients undergo consultation or surgical treatment to solve this problem. Various treatments such as temporary aspiration and drainage, insertion of various catheters, chest tube insertion, video-assisted thoracoscopic surgery (VATS), and even thoracotomy may be needed, but the main and common treatment of these patients is chest tube insertion [3]. There are many types of chest tubes or catheters, but they are primarily classified by size and method of insertion. These tubes contain a number of holes along the side and tip, all with a slot that serves to identify the nearest exit hole. The internal diameter and length of the chest tubes determine the amount of air or liquid flow throughout the drain based on Poiseuille’s law (liquids) and Fanning’s equation (gases) [4].
There are different types of chest tubes in terms of diameter (with the French measuring scale). In the past, larger size tubes have been recommended for drainage of pleural effusion, but recently, in the studies that have been conducted, the lack of effect of tube size on effusion drainage, rate of complications, and the need to insert a second chest tube or the need for more invasive procedures such as VATS has been proven [3].
Selecting the optimal chest tube size is a central component of patient care aimed at maximizing drainage while minimizing patient discomfort and side effects. The proper tube size to achieve this balance is not known and is highly debated. Currently advocated strategies include the use of larger-sized tubes to facilitate drainage of viscous secretions [5].
Aim
The purpose of our stay was to investigate the difference in efficacy of different chest tube sizes in two random groups of patients with pleural effusion. Our investigation considered factors such as the pain severity score, the duration of complete evacuation of the effusion, the need for a second tube to drain the effusion and the need for more invasive measures.
Material and methods
In this cross-sectional study, patients with pleural effusion who were admitted to teaching hospitals of Birjand, Iran in 2021–2022 were enrolled. Inclusion criteria were having an indication for inserting a chest tube due to parapneumonic effusion, malignant effusion and the patients with severe pleural effusion due to heart failure, as well as consent to participate in this study. Patients with pleural effusion who did not have any indications to insert a chest tube were excluded. The patients were randomly divided into two groups: patients with a 28F chest tube, and patients with a 32F chest tube. Overall, 40 patients (18 patients in the 28F chest tube group, and 22 patients in the 32F chest tube group) were enrolled.
The duration of complete drainage of pleural effusion was evaluated by chest X-ray (CXR). The pain severity was scored subjectively by patients from 0 to 10 in 24–48 hours after insertion of the chest tube. The rate of use of painkillers was also evaluated in 24–48 hours after the insertion of the chest tube. In case of no response to the treatment with the first chest tube, the need to perform more invasive procedures such as insertion of a second chest tube or VATS was investigated. The factors were entered into a checklist and the statistical analysis was performed.
In this study, the insertion of both types of chest tubes, of size 28F or 32F, in pleural effusion was completely scientific, and no medically unscientific or unethical procedure was performed on the patient. Also, informed consent was obtained from all participants. Finally, this study was approved by Birjand University of Medical Science’s Research Ethics Committee (Approval ID: IR.BUMS.REC.1401.346).
Statistical analysis
The obtained information such as demographic information and other variables in two groups of 28F and 32F chest tubes were entered into SPSS statistical software (IBM SPSS Statistics for Windows, Version 27.0. Armonk, NY: IBM Corp) to perform statistical analysis. Qualitative variables were described by frequency. Then, the #x03C7;2 test was used to compare each variable between the two groups. In this study, p < 0.05 was considered significant.
Results
The present study was conducted on 40 patients with pleural effusion referred to teaching hospitals in Birjand, Iran during 2021–2022. Twenty-six (65.0%) of the participants were male and 14 (35.0%) were female. Also, 4 (10.0%) people were in the age range of 0–20 years, 20 (50.0%) people were in the age range of 20–40 years, 15 (37.5%) people in the age range of 4–60 years, and only 1 (2.5%) person was over 60 years old. In this study, 28F and 32F chest tubes were used for 18 (45.0%) and 22 (55.0%) people, respectively (Table I).
Table I
Demographic variables in the two groups
| Variable | n (%) | |
|---|---|---|
| Sex | Female | 14 (35.0) |
| Male | 26 (65.0) | |
| Age range | 0–20 years | 4 (10.0) |
| 20–40 years | 20 (50.0) | |
| 40–60 years | 15 (37.5) | |
| > 60 years | 1 (2.5) | |
| Chest tube size | 28 | 18 (45.0) |
| 32 | 22 (55.0) | |
| Total | 40 (100) |
According to Table II, the duration of complete drainage of pleural effusion varied from 3 days to 10 days. The mean duration of complete drainage of pleural effusion in the groups of patients with 28F and 32F chest tubes was 5.82 ±2.41 days and 5.91 ±2.17 days, respectively. Based on the results, there was no significant difference in terms of the length of time required for the chest tube to remain in place for the complete drainage of pleural effusion in the two groups of patients with 28F and 32F chest tubes (p = 0.593).
Table II
Duration of complete drainage of pleural effusion in the two groups
| Duration | Patients with 28F chest tube | Patients with 32F chest tube | Total | P-value* |
|---|---|---|---|---|
| Mean ± SD | 5.82 ±2.41 | 5.91 ±2.17 | 5.88 ±2.30 | 0.593 |
| 3 days | 1 (5.6%) | 2 (9.1%) | 3 (7.5%) | |
| 4 days | 6 (33.4%) | 4 (18.2%) | 10 (25.0%) | |
| 5 days | 6 (33.4%) | 6 (27.3%) | 12 (30.0%) | |
| 6 days | 1 (5.6%) | 3 (13.6%) | 4 (10.0%) | |
| 7 days | 0 (0.0%) | 3 (13.6%) | 3 (7.5%) | |
| 10 days | 4 (22.2%) | 4 (18.2%) | 8 (20.0%) |
According to Table III, the pain severity score varied from 4/10 to 8/10. The mean severity score in the groups of patients with 28F and 32F chest tubes was 6.71 ±1.02 and 6.48 ±1.21, respectively. There was no significant difference in terms of pain severity in the two groups of patients with 28F and 32F chest tubes (p = 0.560).
Table III
Pain severity score in the two groups
| Duration | Patients with 28F chest tube | Patients with 32F chest tube | Total | P-value* |
|---|---|---|---|---|
| Mean ± SD | 6.71 ±1.02 | 6.48 ±1.21 | 6.58 ±1.15 | 0.560 |
| 4 | 1 (5.6%) | 2 (9.1%) | 3 (7.5%) | |
| 5 | 1 (5.6%) | 2 (9.1%) | 3 (7.5%) | |
| 6 | 6 (33.4%) | 5 (22.7%) | 11 (27.5%) | |
| 7 | 6 (33.4%) | 8 (36.4%) | 14 (35.0%) | |
| 8 | 4 (22.2%) | 5 (22.7%) | 9 (22.5%) |
All patients in both study groups needed to receive painkillers and no significant difference was observed in terms of the need to receive painkillers in the two groups of patients with 28F and 32F chest tubes (p = 1.000).
The need for more invasive procedures such as VATS and second chest tube insertion was evaluated. Based on the results, 5 (27.8%) and 2 (9.1%) patients needed more invasive procedures such as VATS and second chest tube insertion in the groups of patients with 28F and 32F chest tubes, respectively. There was no significant difference in terms of need for more invasive procedures such as VATS and second chest tube insertion in the two groups of patients with 28F and 32F chest tubes (p = 0.088).
Discussion
Proper management of chest tubes is very important in the post-insertion care of these tubes. However, thoracic surgeons have traditionally managed chest tubes based more on their experience and personal preference than by an evidence-based approach [6]. Usually, the chest tube is removed when the daily pleural effusion volume drops below a certain volume or an air leak is not detected [7]. Chest tubes are available in different sizes, each of which can be used for different conditions and patients. Chest tubes with sizes of 28F and 32F are the most common chest tubes used in adults. Various studies have been conducted on evaluating the effect of chest tube size on the clinical outcomes of patients, complications, and other variables, and the findings have been contradictory [8]. Therefore, in this study, we aimed to investigate the effect of chest tube diameter on the amount of drainage and tube performance in patients with pleural effusion referred to the teaching hospitals of Birjand, Iran in 2021–2022.
In this study, the duration of complete drainage of pleural effusion varied from 3 days to 10 days. In both groups of patients with 28F and 32F chest tubes, the chest tube was removed within 5 days in most of the patients, and in fact, the pleural effusion was completely drained during this period. This study found no significant difference in terms of the length of time required for the chest tube to remain in place for the complete drainage of pleural effusion in the two groups of patients with 28F and 32F chest tubes. Most chest tubes are suitable for remaining more than 2 weeks in the pleural space. However, the longer the tube is left, the greater is the risk of local infection. On the other hand, aspiration drainage systems designed for therapeutic thoracentesis (8F), which may sometimes be used to drain small emphysematous collections, are usually made of polyurethane and must be removed no later than 3 days after initial insertion [9]. In pneumothorax, the acceptable airflow for chest tube removal in the absence of suction is less than 20 ml/min for 8–12 hours or less than 40 ml/min for 6 hours [9]. In cases of pleural effusion, there is no definitive standard reported for the fluid output threshold for chest tube removal and it depends on the individual’s underlying disease. After surgery, chest tubes can be safely removed with a daily output of up to 450 ml/24 hours [9]. After pleurodesis, some pulmonologists do not remove chest tube when fluid output falls below 100 to 150 ml/day, while others remove chest tube at a specified time (e.g., 24 hours), regardless of the volume of fluid output [10]. Consistent with our study, Orlando et al. found that small chest tubes had a significantly slower mean initial outflow velocity than large chest tubes; however, a parametric analysis detected no significant difference in the average output of small and large chest tubes [8]. Thus, it can be said that the size of the chest tube has no effect on the duration of the tube remaining or the duration of drainage.
Although in the present study patients with a 32F chest tube reported greater pain severity, this difference was not statistically significant. Contrary to the results of our study, Rahman et al. found that pain severity was significantly higher in patients with larger chest tubes (mainly due to blunt dissection insertion). These investigators found that smaller chest tubes inserted with a guidewire caused less pain than larger tubes inserted by blunt dissection, with no difference in clinical outcome in the treatment of pleural infection [5]. One potential reason for the difference in the findings of the two studies may be related to the person-centeredness of the pain assessment tool in our study. The tool used to evaluate the pain severity is subjective and not objective, so the findings might not be completely representative of the study population. It should be noted that the pain severity perceived by patients for whom a chest tube has been inserted is related to the damage caused to the muscles of the chest wall during the insertion of the chest tube and subsequently the pressure applied on the intercostal nerves. Moreover, in pigtail catheters that are placed with the Seldinger technique, due to the fact that the amount of damage to the chest wall is lower, the perceived pain severity of the patients is also lower [11–13]. On the other hand, in the present study, all the studied subjects used painkillers for pain relief, which could be one of the reasons for the lack of difference in pain severity between the two groups.
In the current study, approximately 28% of patients with a 28F chest tube and 9% of patients with a 32F chest tube needed more aggressive procedures, including the insertion of a second chest tube or VATS. Although the percentage of people who needed these procedures was higher in the 28F chest tube group, no significant difference was observed when compared with the patients in the 32F chest tube group. Contrary to the results of the present study, studies conducted by Bauman et al. [14], Tanizaki et al. [15], and Kulvatunyou et al. [16] found that the need for more aggressive procedures such as VATS or placement of a second chest tube is more common in patients for whom a larger size chest tube has been used. One possible reason for this difference in the findings is related to the lack of specific guidelines regarding indications for the use of more invasive measures. For example, in the study of Bauman et al. [14], the hospital’s policy was to use the VATS procedure early during the first week, usually on the 3rd to 5th days. In various studies, decisions on how to treat residual fluid in the pleural space are made based on daily clinical status, as well as daily findings obtained from CXR and computed tomography (CT) scan.
Nowadays, many different sizes of chest tubes are available. Choosing the optimal chest tube size is a key component of patient care. With the proper selection of chest tube, the maximum speed of drainage and, at the same time, minimal discomfort and side effects will be created for the patient. In general, the optimal chest tube size to achieve this balance is not known and is highly debated. In the past, the common strategy included the use of larger chest tubes to facilitate drainage of viscous purulent secretions [17–21], and small chest tubes were usually used when re-drainage of secretions was required [22]. Despite this view, several studies have reported therapeutic success in draining secretions with smaller tubes, with apparently reduced pain [23–25]; thus the trend is toward the use of smaller chest tubes.
Several new guidelines provide guidance for chest tube use, including appropriate tube size selection for malignant effusions [26] as well as in the setting of parapneumonic effusions and empyema [27]. The key point in malignant effusions as well as in parapneumonic effusions and empyema is to consider using a small size tube. Smaller chest tubes are potentially successful, with success rates similar to larger chest tubes in the setting of recurrent, symptomatic, malignant pleural effusions for both fluid drainage and administration of sclerosing agents [26]. As noted, smaller chest tubes are an appropriate choice in many cases of pneumothorax and in some patients requiring pleural fluid drainage. One of the limitations of this study was the small number of people included. The factors evaluated were also limited, which made it impossible to conduct a comprehensive and complete evaluation of the causes. In order to obtain reliable results, it is necessary to carry out a comprehensive and complete study regarding indications for the insertion of each type of chest tube.
Conclusions
Overall, the study showed no significant differences between the two groups of patients with different chest tube sizes in terms of various factors, including drainage duration, need for invasive procedures, pain levels, and pain medication usage. While smaller chest tubes seem to be an appropriate choice, further research with larger sample sizes and more variables is recommended.
