Background: Traumatic hemothorax and pneumothorax are common injuries for which conventional treatment is large bore chest tube placement. Increasingly, small bore pigtail catheters are used to treat non-traumatic pneumothorax and pleural effusions, however they have not been widely adopted for trauma. The objective of this systematic review is to examine the evidence behind pigtail catheter use in traumatic and iatrogenic hemothorax and pneumothorax. Methods: We searched PubMed and Embase databases and selected all studies that examined the use of pigtail catheters in traumatic or iatrogenic hemothorax or pneumothorax. Pediatric studies were excluded. We evaluated the quality of each study using GRADE criteria. A meta-analysis was completed to compare the success rate of pigtail catheter placement for traumatic or iatrogenic pneumothoraces. Many of the studies did not have a comparison group rendering the data insufficient to analyze chest tube success rates. Data on other endpoints were too heterogeneous to synthesize quantitatively. Results: We identified two studies of pigtail catheter use in traumatic hemothorax, two studies in traumatic pneumothorax, and four studies in iatrogenic pneumothorax. Success rates with a pigtail catheter ranged from 92% to 100% for traumatic hemothorax, 89% to 95% for traumatic pneumothorax, and 71% to 88% for iatrogenic pneumothorax. Our meta-analysis yielded a pooled success rate of 85% for pigtail catheters treating iatrogenic and traumatic pneumothorax. Conclusion: The use of pigtail catheters in trauma is promising, but the current literature is insufficient to support their use. Further study is warranted, and a large randomized controlled trial would be beneficial.
Traumatic hemothorax and pneumothorax are common injuries for which conventional treatment has been large bore (28-40 Fr) chest tube placement. Increasingly, small bore pigtail catheters are used to treat non-traumatic pneumothorax with similar success rates and duration of placement when compared to chest tubes . Pigtail catheters, rather than large-bore chest tubes, are also used to drain pleural effusions . Pigtail catheters were first introduced for the treatment of pleural pathology in the 1980s [3,4]. They have been used in the pediatric population with low failure rates [5-7], and have gained acceptance for treating spontaneous pneumothoraces [1,8] and pleural effusions [2,9]. Despite the shift to pigtail catheters for many conditions, their use has not been widely adopted for the treatment of traumatic hemothorax and pneumothorax.
Compared to standard chest tubes, pigtail catheters are placed through smaller incisions with less insertion-related trauma to the intercostal muscles. Because of their size, flexible material and insertion technique, pigtail catheters result in decreased pain and pain medication use, and possibly shorter length of hospital stay [10-12].
There are theoretical concerns about the ability of pigtail catheters to drain blood adequately, due to their smaller diameter, resulting in retained hemopneumothorax . The safety and effectiveness of pigtail catheters in patients with injury from thoracic trauma has not been well demonstrated. Thoracic trauma occurs after blunt trauma, penetrating trauma, or iatrogenic injury to the pleura, most commonly from a needle during central venous catheter insertion. The purpose of this systematic review is to determine the overall success rate of pigtail catheters in patients with traumatic or iatrogenic hemothorax and pneumothorax.
This study was confirmed by the IRB to be exempt from review. Participants were adults (18 years or older) who underwent pigtail catheter or large-bore tube thoracostomy placement for traumatic pneumothorax, traumatic hemothorax, or iatrogenic pneumothorax. Iatrogenic injury was considered to be a form of traumatic injury to the pleura or lung parenchyma, and these studies were included in the analysis. We excluded studies and subjects with pleural effusions and medical etiologies of pneumothorax, such as spontaneous pneumothorax. Other comparison groups including alternative catheter types (central lines, small bore chest tubes, etc.) were not included.
We focused on pigtail catheters rather than all types of small-bore catheters because the latter group is not well defined. The insertion procedure for a pigtail catheter is the least invasive approach differing from all other insertion procedures for other types of tubes and catheters. The comparison group, when available, had placement of a standard, large bore chest tube (28 Fr or greater).
The primary outcome is the success rate for the pigtail catheter or chest tube. The definition of success rate was described in heterogeneous terms, however, the failure rate definitions were similar and described persistent symptoms or imaging findings. Seven of the eight total studies examined the need for additional pigtail catheters, chest tubes, or other interventions as a defining factor for failure. One study  did not specify the need for additional intervention as a failure. To calculate success, we subtracted the failed pigtail catheter or chest tube placements from the total and divided by the total.
Data for pigtail catheters were compared with large bore chest tubes when applicable, but several studies did not include homogeneous comparison groups. Endpoints including post-operative pain and pain medication requirements were initially gathered but proved too heterogeneous to draw meaningful conclusions.
Target Study Design
We targeted clinical trials or observational studies, prospective or retrospective, which evaluated pigtail catheter use for patients with traumatic pneumothorax, traumatic hemothorax or iatrogenic pneumothorax.
Search and Selection of Studies
Systematic reviews of pigtail catheter placement for traumatic pneumothorax and hemothorax were performed separately, using the PubMed and EMBASE databases. See Figure 1 for the PRISMA diagram of this search. Two independent investigators performed the literature search and the results were pooled. Selected abstracts were reviewed to determine eligibility and manuscripts were obtained for studies that warranted detailed review. Publications selected by either investigator were reviewed in more detail to determine eligibility to maximize the sensitivity of the search. The investigators reviewed all included manuscripts to ensure eligibility and to extract pertinent, predetermined data. We further reviewed the bibliographies of the included studies, to find additional qualifying studies.
The literature search was performed between September and November, 2014. Medline identified 128 records with an additional 140 records identified between Embase, Web of Science, and review of citations from the included records, for a total of 268 screened records. Please see appendix 1 for complete search terms. A total of 235 records were excluded for duplication or non-relevant topic identified in the abstract. Full text records of 33 publications were reviewed. Twenty-five publications were excluded due to inclusion of children (n=10), non-traumatic etiology of pneumothoraces/hemothoraces (n=13), or use of other types of catheters (n=2) leaving eight studies for review. Meta-analysis of pigtail catheter use in traumatic pneumothorax included 5 of the 8 studies. Three publications examined pleural pathology broadly, but included iatrogenic pneumothoraces, with insufficient data specific to the iatrogenic pneumothorax patients to be included. The corresponding authors of these studies were contacted, and data were obtained for one of the three studies. Please see Table 1 for a summary of the included studies.
Table 1. Summary of Studies.
Study limitations were evaluated using the GRADE (Grade of Recommendation, Assessment, Development, and Evaluation) criteria . The majority of studies were retrospective and without comparison groups, lacking adequate control groups for confounding factors. Based on the GRADE criteria, the majority of studies fell into the “weak” grade of recommendation and “low” level for quality of evidence.
The success rate of pigtail catheter placement for traumatic or iatrogenic pneumothoraces was assessed using a random effects model since trials were expected to be heterogeneous in their design and patient populations. Proportions and 95% confidence intervals were calculated. Many of the studies did not have a comparison group rendering the data insufficient to analyze large-bore chest tube success rates. Data on other endpoints including complication rate and hospital length of stay were too heterogeneous to synthesize quantitatively.
Statistical heterogeneity was examined using the chi-square and I2 tests for heterogeneity. Data were analyzed using STATA 11.0 statistical software (STATA Corp, College Station, TX) with weighting for size of the study. See Figure 2 for a Forest Plot of this data.
Please see Table 2 for a summary of outcomes in the individual studies
Table 2. Outcomes.
The search for pigtail catheter use in traumatic hemothorax returned two studies that fit the criteria. One study  was a prospective observational study that found that pigtail catheters drain blood as effectively as large bore chest tubes. The study prospectively evaluated 36 pigtail catheters for their effectiveness in treatment of traumatic hemothorax. The pigtail catheters were compared to 191 chest tubes, evaluated retrospectively. The primary outcome was initial chest tube output upon insertion, which was similar between the two groups (560±81 mL in the pigtail catheter group and 426±37 mL in the chest tube group). Tubes were placed approximately one day later in the pigtail catheter group, and the failure rates were not statistically different (8% in the pigtail catheter group and 24% in the chest tube group).
The second study  retrospectively studied the use of ultrasound-guided pigtail placement for drainage of pleural effusions in the ICU and included three cases of traumatic hemothorax. All three traumatic hemothorax cases had successful resolution of the hemothorax, with a mean pigtail time of 6 days and a mean ICU length of stay of13 days for those three patients.
The search for use of pigtail catheters in traumatic pneumothorax returned one randomized controlled trial and one retrospective study, both from the same group of investigators.
The retrospective study , published in 2010, examined 219 patients with traumatic pneumothorax, of which 75 received a pigtail catheter and 146 received a large bore chest tube. The pigtail catheter group had a success rate of 89%, with the tube in place for a median of 4 days and a median hospital stay of 6 days. The chest tube group had a success rate of 96% with the tube in place 4.4 days and a hospital stay of 15 days. Success rate and indwelling tube time were not significantly different, although the difference in length of hospital stay was statistically significant.
Figure 2. Success rate of pigtail catheter placement
This retrospective study paved the way for a randomized controlled trial  which evaluated 40 patients between July 2010 and February 2012. Patients were randomized to 14 Fr pigtail catheter placement (n=20 patients) versus 28 Fr open chest tube placement (n=20 patients). Primary outcomes were tube-site pain and total pain medication use, and secondary outcomes were success rate and complication rate. Pain scores were significantly lower in the pigtail catheter group at insertion (3.2 vs. 7.7, p<0.001), at day 1 (1.9 vs. 6.2), and at day 2 (2.1 vs. 5.5). Use of pain medication was not significantly different. Success rate was similar at 95% in the pigtail catheter group and 90% in the chest tube group. There were two complications in each group for a complication rate of 10% per group. Duration of indwelling catheter and hospital length of stay were similar.
The search for use of pigtail catheter in iatrogenic pneumothorax returned four retrospective studies.
Laronga et al reviewed data on 100 subjects who sustained pneumothoraces during central line placement . The patients fell into three groups: 58 underwent observation, 34 had pigtail catheters placed, and 8 had chest tubes placed. Pigtail catheter placement carried an 85% success rate with the tube in place for 1.6 days and no hospital stay as the patients were discharged and treated as outpatients with pigtail catheters in place. Chest tube placement had an 88% success rate with a 3.7 day stay (HOSPITAL) stay and no data on the number of days with the tube in place. Observation alone had a success rate of 60%.
Lin et al  examined 62 mechanically-ventilated subjects with 70 pneumothoraces, of which 40 were iatrogenic and 30 were due to barotrauma.
The iatrogenic pneumothoraces were included in the analysis, but the pneumothoraces due to barotrauma were excluded. Pigtail catheter drainage had a success rate of 87.5%, with the tubes in place for 5.9 days and a length of hospital stay of 33.3 days. There was no comparison group.
Liu et al  studied ultrasound-guided pigtail catheter placement for various pleural pathologies, of which 64 were pneumothoraces. The authors were contacted and provided raw data to analyze the iatrogenic pneumothorax group separately. Eight subjects underwent pigtail catheter placement for iatrogenic pneumothorax, of which 4 were successful, for a success rate of 50%. Three subjects underwent pigtail catheter placement for traumatic pneumothorax, with 2 successful for 67% success (RATE).
Noh et al  reviewed 105 subjects who had iatrogenic pneumothoraces, of which 31 underwent 14 Fr pigtail catheter placement, 25 were treated with 7 Fr central lines placed in the chest and 49 had small bore (10 Fr) chest tubes placed. The groups with central lines and chest tubes were excluded from analysis for reasons described in the Methods section. The pigtail catheters had a success rate of 71%.
The forest plot representing the pooled analysis of pigtail catheter success for traumatic or iatrogenic pneumothoraces is shown in Figure 2. The pooled success rate with pigtail catheters was 85%. Included studies were moderately heterogenous (I2 =57.2%). No other outcomes were evaluated because the outcomes measured were not equivalent (e.g. pain scores cannot be compared to narcotic usage).
Open tube thoracostomy has long been the standard of care for pneumothoraces and hemothoraces of traumatic or iatrogenic etiology. It is an established, safe, and effective procedure, however dividing and stretching intercostal muscles leads to significant postoperative pain and narcotic use.
Pigtail catheters were first introduced in the 1980s and were soon used in the treatment of nontraumatic thoracic pathology [3,4]. Significant data exist on the use of pigtail catheters for drainage of pleural effusions ; however, hemothorax is a distinct process. An undrained or inadequately drained hemothorax has a higher risk of becoming an empyema .
Although there are data on the use of pigtail catheters for treatment of other etiologies of pneumothorax, traumatic and iatrogenic pneumothoraces are distinct from such disease processes, mostly due to the potential for concomitant hemothorax or other associated injuries. Hemothorax may not adequately drain or may clog a small bore pigtail catheter. The potential benefits of pigtail catheters including reduced pain and pain medication use have led to increased interest in their use in trauma patients.
Initial operative decision-making for a massive traumatic hemothorax is based on physiologic status and the amount of blood in the chest. Initial chest tube output in excess of 1500 cc prompts early thoracotomy, and more than 200 mL/hour output over 2-4 hours indicates significant ongoing hemorrhage requiring operative intervention . Flow through a tube is dependent on radius to the fourth power, according to Poiseuille’s law, therefore utilizing a narrower tube could theoretically lead to a lower flow rate. The degree to which pigtail catheters affect initial and ongoing hemothorax drainage volumes is unclear. Regardless of the use of a pigtail catheter or chest tube, one must account for a potential retained hemothorax if the tube is not draining effectively.
The current systematic review evaluated the use of pigtail catheters for three trauma-related thoracic pathologies. Few studies exist on these subjects (two for traumatic hemothorax, 2 for traumatic pneumothorax and four for iatrogenic pneumothorax). The few studies that do exist suffer from small patient numbers and lack of a control group. Most are retrospective studies, with potential confounding and selection bias.
Based on the limited data that exist, success rates with a pigtail catheter ranged from 92% to 100% for treatment of traumatic hemothorax (76% with a standard chest tube), 89% to 95% for traumatic pneumothorax (90-96% with a chest tube), and 71% to 87.5% for iatrogenic pneumothorax (88% with a chest tube). Our meta-analysis identified a success rate of 85%, however the descriptive statistics suggest substantial heterogeneity in the studies. We postulate that the use of pigtail catheters may be safe and effective in uncomplicated traumatic hemothorax and pneumothorax, however the current literature is insufficient and further study is warranted.
The main limitation of the current analysis is the shortage and low quality of available studies. The majority of the studies are retrospective and there were no high quality studies. The lack of a control group in most of the studies renders the data less valuable. Thus, our limited findings cannot clearly be applied to the trauma patient population.
Based on this data, the use of pigtails in trauma is likely safe and effective, however the nature of the included studies provides low-level evidence. Further research is warranted prior to widespread use, and a large randomized controlled trial would be beneficial.
We have no additional acknowledgements. There were no outside funding sources.
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