Efficacy of a novel steerable chest tube system in a swine model of hemothorax

The thoracostomy tube, commonly known as the chest tube, is the standard of care for management of thoracic trauma. It is an indispensable tool for civilian and military treatment of cardiothoracic conditions, including hemopneumothorax, hemothorax, and pneumothorax. Hemothorax, characterized by the accumulation of blood in the pleural space, occurs 300,000 times annually in the United States and can lead to life-threatening conditions (1,2). However, despite their ubiquitous use in lifesaving procedures, thoracostomy tubes remain largely undeveloped when it comes to increasing the efficacy of evacuating blood from the pleural space (3). Fluid in the pleural space due to hemothorax may be loculated and is not always free flowing (4). Attempts for drainage by a traditional chest tube alone may not be successful and often necessitate more invasive methods of drainage, such as video-assisted thoracoscopic surgery (VATS) and open thoracotomy (4). In the cardiothoracic surgery field, there are valid concerns about inadequate chest tube draining that need to be addressed to minimize morbidity and reduce the need for surgical interventions.

Another significant limitation of the traditional chest tube is that the external portion becomes unsterile upon completion of the thoracostomy procedure. Consequently, if a positional complication arises or fluid drainage is impeded, delayed repositioning of the chest tube is not easily feasible. Furthermore, if imaging, such as a chest X-ray or computed tomography scan, later reveals a retained hemothorax, it is difficult to address the retained fluid. Here we describe an investigation of a novel steerable chest tube system, the SAM repositionable chest tube (RCT) (SAM Medical, Tualatin, OR, USA), for the management of hemothorax. The RCT is designed with two-axis steerable manipulation that allows the user to reposition the internal mechanisms whether under fluoroscopic guidance or blindly to facilitate drainage of fluid while maintaining sterility.

Using a swine model of retained hemothorax developed by our laboratory, we investigated the efficacy of the RCT (5). We hypothesized that the treatment of hemothorax with RCT would result in an increase of evacuated blood from the pleural space as evidence by blood volume, and a decrease of residual clot in the pleural space as evidenced by weight of clot collected upon gross pathological examination. We present this article in accordance with the ARRIVE reporting checklist (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-1150/rc).

Experiments were performed under a project license (IP00003846) granted by the Institutional Animal Care and Use Committee of Oregon Health & Science University, Portland, OR, USA, in compliance with The Guide for the Care and Use of Laboratory Animals in a facility accredited by the Association for Assessment and Accreditation of Laboratory Animal Care. A protocol was prepared before the study without registration. The animal model selected and described below is based on the previously described swine model of hemothorax creation (5).

Six male swine (78.2±2.1 kg) from a single source vendor (Oak Hill Genetics Inc., Ewing, IL, USA) were sedated with intramuscular (IM) Telazol (Zoetis, Parsipanny, NJ, USA) and anesthesia maintained with Isoflurane after oro-tracheal intubation for the entire duration of the experiment until euthanasia. Mechanical ventilation was set to volume control with a tidal volume of 8 mL/kg and the respiratory rate was adjusted to maintain an end tidal carbon dioxide between 35 and 45 mmHg. After intubation, swine received IM buprenorphine for intraoperative analgesia. Vascular access was achieved via ultrasound-guided percutaneous technique (Seldinger) for administration of fluids and hemorrhage. Thoracic cavity access was also achieved using percutaneous access for creation of the hemothorax. Position in the thoracic cavity was confirmed with air aspiration. The locations for placement of chest tubes were marked bilaterally at the fourth intercostal space along the midaxillary line.

Both sides of the pleural cavity were used so each animal had an RCT side and a traditional chest tube side. The device side was randomized for each animal using the coin flip method. Bilateral mini-thoracotomies were performed, and chest tubes were placed superior-posteriorly at a depth of 10–12 cm. A traditional straight 28-Fr chest tube was used for the control article. The RCT, 28-Fr, was used per manufacturer’s instructions (Figure 1 and Figure S1). Briefly, the device was removed from its sterile packaging, and the device actuator was rotated to verify function. A stylet was used to penetrate the pleural space, and the RCT was guided over the stylet. Once inserted, the stylet was removed, and the RCT was connected to suction. Both chest tubes were sutured to the skin and connected to individual dry-suction apparatuses (Ocean 2050, Getinge, Wayne, NJ, USA) in the absence of suction, and the tubes were clamped to prevent drainage until intervention.

Figure 1 SAM RCT device. (A) RCT device in packaging. (B) Fully assembled RCT device with insertion stylet. RCT, repositionable chest tube.

To create the retained hemothorax, the bilateral thoracic cavity introducers were connected to the carotid artery introducers, and 2 L of autologous blood was then withdrawn from the carotid arteries and infused into the pleural spaces at a rate of 50 mL per min per side (1 L per side). The hemothorax creation took a total of 20 min. Five min prior to the completion of the hemothorax infusion, 3 L of 5% dextrose in lactated Ringer’s was given to mitigate hemorrhage-induced cardiac arrest.

Autologous blood was allowed to clot undisturbed for 30 min post-hemothorax creation. At that time, clamps were released, and suction was commenced at 20 cmH₂O. The traditional chest tube was not manipulated for the remainder of the study duration. Upon application of suction [time (T) =0 min], the RCT vacuuming procedure, where the RCT is swept laterally along a single plane with the external handle, was commenced per manufacturer’s instructions and continued for 10 min. The procedure was repeated hourly for a total of two vacuuming procedures.

Evacuated blood volume was recorded for both devices for the entirety of the experiment (T =120 min). At the end of the protocol, animals were euthanized with 1 mL/10 lb of euthanasia solution (VetOne, MWI Animal Health, Boise, ID, USA). Retained hemothorax was collected with pre-weighed lap sponges after a median sternotomy was performed. The thoracic cavity was manually explored to confirm proper placement of devices and introducers. Cardiac, pulmonary, and diaphragmatic tissue was grossly assessed for evidence of injury.

Experimental group size (n=6/group) was determined a priori by using a Student’s t-test model (difference between two independent means) with an effect size (ρ) =1.68, α=0.05, and 1 − β =0.80 (G*Power 3.1.9.7). Effect size was determined from previous experiments using the same model where n1=n2 and the mean ± standard deviation (SD) for the compared outcomes (group 1 and group 2) were 695±65 and 592±57 mL, respectively (5). Drainage data and retained hemothorax data were analyzed with Student’s t-test. All statistical analysis was performed using SigmaPlot 12 (SyStat Software Inc., Chicago, IL, USA).

Six animals were successfully enrolled in the study. A hemothorax introducer was incorrectly placed in one of the animals, so the investigators excluded that side of the animal, however the animal was not censored completely from the experiment. Thus, six RCTs and five traditional chest tubes were included in the final analysis.

Pleural drainage was measured throughout the experiment, and the RCT demonstrated increased drainage volume over the traditional chest tube throughout the experiment (Figure 2). Per our a priori hypothesis, drainage was statistically compared between groups at T =10 min and T =120 min. While there was not a difference in drainage at T =10 min (P=0.38), use of the RCT resulted in a statistically significant increase in drainage at T =120 min (Table 1, P=0.03). Although the volume of the retained hemothorax was observed to be lower for RCT at end of study, this did not achieve statistical significance (Table 1, P=0.054).

Figure 2 Drainage volume over time for the RCT and traditional chest tubes (mean ± SD). RCT Vac, 10-min period of vacuuming procedure of RCT in accordance with manufacturer’s instructions. Suction only, traditional chest tube section without manipulation. RCT, repositionable chest tube; SD, standard deviation.

There were no cardiac, pulmonary, or diaphragmatic injuries noted upon necropsy attributable to the use of the RCT or the traditional chest tube.

Here, we demonstrated the impact of two-axis steerable manipulation on the efficacy of chest tube technology. Use of the RCT is an effective tool for blood evacuation from the pleural space, with the RCT consistently outperforming a traditional chest tube in drainage volume over time. We also successfully deployed a model of hemothorax in swine that demonstrated repeatability in the presence and absence of the test device and consistency with previous data generated by this model (5).

The successful placement of a chest tube is critical for its effectiveness (6). Positional complications are a common culprit when traditional chest tubes do not perform adequately, often necessitating the placement of a new tube with an additional operative intervention (7). The consequences of insufficient chest tube drainage increase strain on the health of the patient, provider demands, and costs associated for both parties (8). Therefore, proficient chest tube drainage is vital to surgical outcomes. This supports the concept that providing the potential ability to adjust chest tube position to facilitate pleural space drainage can improve patient outcomes and reduce hospital resource strain. In this study, we deployed the RCT in its most basic clinical application, where the tube was repositioned blindly under the assumption that clotting in the pleural space may restrict chest tube output in the absence of repositioning. Our study suggests that the novel RCT may be more effective than a traditional chest tube at increasing drainage from the pleural space, as evidenced by both the significantly increased level of drainage and the trend toward a reduction in retained clot. In addition, it allows for external handling of the position of the tube without compromising sterility or the need for re-insertion of the tube itself. These results are consistent with our previous study, where we found that the ability to reposition a chest tube while maintaining sterility improves the efficacy of drainage (5).

Other studies have suggested that chest tube location does not influence the need for secondary interventions as long as the tube resides in the pleural space (9,10). However, we found that an RCT increased drainage outcomes (Figure 2). We hypothesize that this may be due to mechanical disruption of clot, the optimization of anatomical placement, or other factors yet to be investigated. Further research into this phenomenon, along with collecting objective data to measure internal manipulation, is warranted as the current RCT experimental model was not designed to answer this question.

Although the data provided is encouraging for clinical applications, results must be interpreted cautiously as we used a swine model of retained hemothorax.

Another limitation of this study was the small sample size. Despite the fact that sample size was determined by an a priori power analysis based off of previous research in this model, the study was underpowered to detect a statistically significant difference in retained hemothorax between groups. Additionally, the statistically significant difference in drainage should be interpreted cautiously as it may not necessarily translate to a clinically relevant outcome. Further research with larger sample sizes based off of this study’s results will be required to properly evaluate the RCT’s efficacy in reducing retained hemothorax. Future studies may also include fluoroscopic guidance to demonstrate that the RCT can be manipulated to be positioned optimally as compared to traditional chest tube placement.

The RCT is effective in evacuating blood through its maneuverable design in a model of retained hemothorax. However, despite being steerable and significantly increasing overall pleural drainage volumes, the catheter was unable to significantly reduce the overall retained clot burden. Development has continued for the RCT to leverage technologies including novel irrigation solutions that facilitate the breakdown of residual clot. Such improvements would allow for the RCT to evacuate clot in addition to blood under normal hospital vacuum conditions and would further address the issue of occluded chest tubes leading to patient complications. Additional research will be required to develop and test these novel iterations of the RCT.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the ARRIVE reporting checklist. Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-1150/rc

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-1150/prf

Funding: This work was supported by SAM Medical, Tualatin, OR, USA.

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-1150/coif). All authors report that they are from Benchmark Biotech LLC. SAM Medical provided study funding and funding for test devices. The authors retained full editorial control of the presented manuscript. The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. Experiments were performed under a project license (IP00003846) granted by the Institutional Animal Care and Use Committee of Oregon Health & Science University, Portland, OR, USA, in compliance with The Guide for the Care and Use of Laboratory Animals in a facility accredited by the Association for Assessment and Accreditation of Laboratory Animal Care.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Sorino C, Feller-Kopman D, Mei F, et al. Chest Tubes and Pleural Drainage: History and Current Status in Pleural Disease Management. J Clin Med 2024;13:6331. [Crossref] [PubMed]
2. Mowery NT, Gunter OL, Collier BR, et al. Practice management guidelines for management of hemothorax and occult pneumothorax. J Trauma 2011;70:510-8. [Crossref] [PubMed]
3. Lobdell KW, Engelman DT. Chest Tube Management: Past, Present, and Future Directions for Developing Evidence-Based Best Practices. Innovations (Phila) 2023;18:41-8. [Crossref] [PubMed]
4. Esmadi M, Lone N, Ahmad DS, et al. Multiloculated pleural effusion detected by ultrasound only in a critically-ill patient. Am J Case Rep 2013;14:63-6. [Crossref] [PubMed]
5. Donaldson RI, Zimmermann EM, Buchanan OJ, et al. Efficacy of a novel chest tube system in a swine model of hemothorax. J Thorac Dis 2021;13:213-9. [Crossref] [PubMed]
6. Anderson D, Chen SA, Godoy LA, et al. Comprehensive Review of Chest Tube Management: A Review. JAMA Surg 2022;157:269-74. [Crossref] [PubMed]
7. Roebker JA, Kord A, Chan K, et al. Chest Tube Placement and Management: A Practical Review. Semin Intervent Radiol 2023;40:231-9. [Crossref] [PubMed]
8. Baribeau Y, Westbrook B, Baribeau Y, et al. Active clearance of chest tubes is associated with reduced postoperative complications and costs after cardiac surgery: a propensity matched analysis. J Cardiothorac Surg 2019;14:192. [Crossref] [PubMed]
9. Kugler NW, Carver TW, Knechtges P, et al. Thoracostomy tube function not trajectory dictates reintervention. J Surg Res 2016;206:380-5. [Crossref] [PubMed]
10. Benns MV, Egger ME, Harbrecht BG, et al. Does chest tube location matter? An analysis of chest tube position and the need for secondary interventions. J Trauma Acute Care Surg 2015;78:386-90. [Crossref] [PubMed]