Introduction

Thoracic surgery is frequently performed in veterinary patients to treat congenital and acquired diseases affecting the heart, lungs, pleura, mediastinum, thoracic wall, and diaphragm.¹ Thoracostomy drain placement is indicated following thoracic surgery and for treatment of pleural disease in patients that require repeated thoracocentesis.^2,3 There are numerous commercially available thoracostomy drains with various sizes, materials, tissue compatibility, and cost.^4,5 In general, the diameter of the throacostomy drain should be similar in size to the mainstem bronchus of the patient; however, smaller-diameter chest drains are associated with less pain in humans and have been shown to be an effective alternative to large-bore tubes.^5–8 Small-bore tubes may have the benefit of fewer insertional and infectious complications when compared with larger tubes; however, large veterinary studies evaluating complications with these tubes have not been reported.^8,9 Other tubes can be modified to perform as thoracostomy drains if they meet specific criteria. The tube must be sterile, ideally elicit minimal tissue reaction in situ, have multiple fenestrations at the distal end, and be able to withstand the generation of subatmospheric pressure during suctioning without collapsing.⁵

Jackson-Pratt (JP) drains have traditionally been used for closed suction drainage after surgical procedures where excessive dead space or infection is present.³ JP drains have been used successfully in the management of pleural effusion in humans.¹⁰ Anecdotally, JP drains placed using an open technique have been used as thoracostomy drains in veterinary patients. JP drains offer potential advantages to traditional trocar type (TRO) drains including increased flexibility, smaller size, and possibly increased comfort. Similar to traditional TRO drains, JP drains also allow for continuous suction and reservoir collection to monitor fluid quantity and quality.¹¹

To our knowledge, the complication rate of JP drains after thoracotomy has not been reported. The objective of this study was to evaluate the efficacy of JP thoracostomy drains and compare them with TRO thoracostomy and guidewire (GW) thoracostomy drains placed in open fashion after thoracotomy. Our null hypothesis was that JP drains would not be associated with increased complications or need for pain medications as compared with both TRO and GW thoracostomy drains.

Materials and Methods

Medical records of canine and feline patients who underwent thoracic surgery at the Matthew J. Ryan Veterinary Hospital University of Pennsylvania from 2013 to 2018 were evaluated. Dogs and cats were included in the study if they underwent intercostal thoracotomy (ICT), median sternotomy (MS), or a thorascopic surgery and had a thoracostomy drain placed intraoperatively. Cases with incomplete medical records or that were euthanized during surgery without drain placement were excluded from the study population. Seventy-six throacotomies were reviewed. Nine thoracotomies were not included as a result of incomplete medical records and two were excluded as a result of euthanasia secondary to the primary disease process.

All thoracostomy drains were placed by an American College of Veterinary Surgeons board-certified veterinary surgeon or by a surgical resident under direct supervision. JP thoracostomy drains^a were placed retrograde using the attached trocar included in the JP drain kit (Figure 1). The trocar was initially introduced intrathoracically through the pleura and muscle. The trocar was then tunneled subcutaneously in a caudodorsal direction three to four intercostal spaces until exiting the skin. The trocar allowed an inside-out placement of the thoracostomy tube instead of the traditional outside-in technique with a hemostat. All drains were placed with the fenestrated end at the cranial aspect of the thoracic cavity.

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TRO thoracostomy drains^b were placed in routine fashion.⁹ A small skin incision in the dorsal third of the lateral thoracic wall at the level of the ninth, tenth, or eleventh intercostal space was made. The tube was advanced subcutaneously in a cranioventral direction for three to four intercostal spaces. The tube was then introduced into the thorax through the muscle and pleura using the stylet or a large hemostat. Visualizing the tube placement intrathoracically, the tube was advanced in a cranioventral direction.

GW thoracostomy drains^c were placed in routine fashion.⁹ A small skin incision in the dorsal third of the lateral thoracic wall at the level of the ninth, tenth, or eleventh intercostal space was made. The introducer catheter was tunneled cranioventrally and inserted at the cranial aspect of the rib into the thoracic cavity. A J-wire was inserted through the catheter in the thorax. The catheter was advanced in a cranioventral direction. The catheter was removed, and the thoracic drainage catheter was inserted over the GW.

All drains were placed during surgery with the fenestrated end placed in the cranial aspect of the thoracic cavity. Thoracostomy drains were secured similarly in all patients with nonabsorbable suture using a finger-trap technique.¹² GW chest drains were additionally secured with two tacking sutures at the base of the drain. All drains were tested at the end of surgery for patency and subatmospheric pressure and capped with Christmas Tree adapters^d, three-way stopcocks^e, and injection caps. To achieve subatmospheric pressure, a syringe was attached to the three-way stopcock until negative pressure was obtained.

Results

Of the 65 thoracotomies included, 48 dogs and 17 cats were included in the study. Twenty-six types of purebreed dog and 11 mixed-breed dogs were included. Four types of purebreed cats and 13 domestic shorthairs were included. The proportion of different types of thoracostomy drains were similar between cats and dogs (P = .999).

The median age of all thoracotomy patients was 8 yr (range 0.25–15 yr). The median age of patients who had TRO thoracostomy drains placed after thoracotomy was 4 yr (range 0.25–13 yr). The median age of patients who had GW thoracostomy drains placed was 6 mo (range 3 mo to 12 yr). The median age of patients who had JP thoracostomy drains placed was 10 yr (range 1–15 yr). Age compared among the groups was significantly different (P = .0008). Patients receiving TRO and GW thoracostomy drains were significant younger than those receiving JP thoracostomy drains (P = .0096 versus .0069, respectively). No age difference was seen between dogs receiving TRO and GW thoracostomy drains (P = .1691)

The median weight of all thoracotomy patients was 6.7 kg (range 1.3–47.3 kg). The median weight of patients who had TRO thoracostomy drains placed was 5.2 kg (range 1.8–41.4 kg). The median weight of patients who had GW thoracostomy drains placed was 5.2 kg (range 1.3-39 kg). The median weight of patients that had JP thoracostomy drains placed was 15 kg (range 3.4–47.3 kg). Weight among the groups was significantly different (P = .0039). Patients receiving TRO and GW thoracostomy drains weighed significantly less than those receiving JP thoracostomy drains (P = .114 versus .0474, respectively). No weight difference was seen between dogs receiving TRO and GW thoracostomy drains (P = .4821).

The most common surgical procedure performed was lung lobectomy (n = 35) performed for solitary pulmonary neoplasia (n = 25); lung lobe torsion (n = 5); spontaneous pneumothorax and pulmonary bullae (n = 2); and one each of traumatic diaphragmatic hernia, lung lobe abscess, and pulmonary thromboembolism. Other procedures performed included ligamentum arteriosum ligation and transection for treatment of persistent right aortic arch (n = 8), thoracic duct ligation, cisterna chyli ablation and subtotal pericardiectomy (n = 6), pericardiectomy (n = 6), patent ductus arteriosus ligation (n = 5), exploratory for pyothorax (n = 2), auriculectomy (n = 1), cranial mediastinal mass resection (n = 1), and epicardial pacemaker implantation (n = 1). The type of thoracostomy drain and associated procedure is shown in Table 1. The approaches included left lateral ICT (n = 26), right lateral ICT (n = 26), MS (n = 7), and thorascopic surgery (n = 6). There was no difference in approach among groups (P = .057).

TABLE 1 Type of Thoracostomy Drain and Associated Procedure

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All thoracostomy drains were patent and functional at the completion of surgery. Thoracostomy drains were left in place for varying lengths of time depending on the underlying disease process, clinical course of the disease, and production of air or fluid aspirated from the drain. The majority of drains were removed within the first 24 hr (n = 52). Only three drains were left in place for >48 hr after surgery. The remainder were removed between 24 and 48 hr after surgery (n = 10).

All animals in this study recovered in the intensive care unit. All animals received at least one type of injectable pain medication in the postoperative period. Sixteen of the 65 (24.6%) received at least one additional pain medication. The most common pain medication used was a fentanyl constant rate infusion (2–5 μg/kg/hr, n = 29) followed by methadone intravenously (0.1–0.2 mg/kg q4-6hrs, n = 26) and buprenorphine (0.01–0.02 mg/kg q 6–8 hr, n = 10). Dexmedetomidine (0.25–5 μg/kg/hr, n = 6), bupivicaine (0.5–2 mg/kg q 6 hr, n = 5) via thoracostomy drain, ketamine (0.1–0.5 μg/kg/hr, n = 3), lidocaine (30–80 μg/kg/hg, n = 1), and butorphanol (0.1–0.3 mg/kg/hr, n = 1) were added as additional pain medications. There was no significant difference seen in number of pain medications used among thoracostomy drain groups (P = .273).

Thirty-one of the patients had JP thoracostomy drains placed. Twenty-five of the patients had traditional TRO thoracostomy drains placed, and 9 had a MILA low-profile thoracostomy drains placed. Fourteen total complications were reported (21.5%); 10 of the complications were minor (15.3%), and 4 of the complications were major (6.2%). Four (28%) of the 14 complications were seen in cats, of which 1 was major and 3 were minor.

Eleven of the 25 patients (44%) with TRO thoracostomy drains had complications, of which 8 were minor (32%) and 3 were major (12%). Minor complications included pain reported to be associated with the drain requiring additional medications (n = 6), serosanguinous discharge from thoracostomy drain insertion site (n = 1), and subcutaneous emphysema around the drain (n = 1).

Three major complications were associated with the TRO thoracostomy drain. In the first case, a large amount of subcutaneous fluid was noted around the incision site of the thoracostomy drain. Subatmospheric pressure was unable to be obtained when the drain was aspirated. As a result of a suspected leak, the thoracostomy drain was clamped proximally. The drain was assessed and a leak in the distal portion near the insertion of the Christmas Tree adapter of the drain was noted. The drain was cut proximal to the leak site and a new cap was placed on the drain. The drain functioned without further complication. In the second case, the dog was noted to be in respiratory distress. There were decreased lung sounds in all fields based on auscultation and a negative glide sign indicating abnormal apposition of the lung and thoracic wall on thoracic-focused assessment with sonography for trauma. A pneumothorax was suspected. The thoracostomy drain was not producing any air or fluid on aspiration at that time. The patient was sedated and the thoracostomy tube was evaluated and repositioned. After repositioning, 60 mL of air was removed from the tube and the thoracostomy drain was secured back in place. In the third patient, subcutaneous emphysema was noted around the thoracostomy drain site. The patient was showing no signs of respiratory distress. The thoracostomy drain was not producing any air or fluid when aspirated. Under sedation, thoracic radiographs were performed, and a pneumothorax was diagnosed. Thoracocentesis was performed to remove the air, and the thoracostomy drain was repositioned. The subcutaneous emphysema continued to progress around the chest tube. Because the thoracostomy drain produced no air or fluid, it was removed. Evaluation of the tube ex vivo showed an air leak at the connection between the distal end of the tube and the integral funnel end containing the Christmas Tree connected to the three-way stopcock.

Three out of the 31 cases (9.6%) with JP thoracostomy drains had complications, of which 2 were minor (6.5%) and 1 was major (3.1%). Minor complications included 2 cases that required additional pain control medications as a result of reported pain when manipulating, palpating, or aspirating the tube.

The only major complication with the JP thoracostomy tube occurred during removal of the tube. In one feline patient, a JP drain fractured (or split) during removal. When removing the tube in this feline patient, the cat suddenly struggled, breaking the tube and necessitating surgery to retrieve the distal tube. None of the nine patients with GW thoracostomy drains had reported complications.

The total complications compared among thoracostomy drain groups were significant (P = .002). The TRO thoracostomy drain had significantly more total complications than the JP thoracostomy tube (P = .009) but not the GW thoracostomy tube (P = .051). No significant difference was seen in total complications between the JP and GW thoracostomy drains (P = .99). There was no significant difference in the number of minor complications when comparing the JP drain with the GW (P = .99) and TRO thoracostomy drain (P = .51). Finally, no differences were seen in the number of major complications when comparing all three drains individually (P = .350).

Discussion

In this study, thoracostomy drains were placed during planned thoracotomies. All drains were functional immediately after surgery and the majority (52/65) were removed within 24 hr of surgery. All but 3 of the thoracostomy drains were removed within 48 hr. In this cohort of dogs and cats, JP drains used as thoracostomy drains had significantly fewer total complications than traditional TRO drains. JP drains are more flexible than TRO tubes and have been used successfully in humans to manage pleural effusions.¹⁰ The one major complication seen when JP drains were used occurred when the tube broke during removal. This was likely as a result of excessive tension applied to the tube as the cat suddenly struggled during removal.

Minor complications seen with the TRO chest drains included accumulation of subcutaneous air or fluid around the stoma the tube. These complications were not seen with either the JP or GW tubes. It is likely that this had to do with the size of the tube and the method of placement during surgery. The TRO drains are larger and are sometimes placed by making an intercostal opening with hemostats. The tube is then grasped with either Kelly or Carmalt forceps and advanced into the chest. The intercostal opening is thus larger than the tube diameter, allowing residual pleural air or fluid to track subcutaneously along the drain. The JP thoracostomy drains were placed using the sharp trocar included in the JP drain kit and the GW drains using a catheter and guidewire. The trocar included in the JP drain kit is approximately the same diameter as the tube, making subcutaneous air or fluid leakage less likely. This could be a potential cause of why the drains placed in standard fashion may leak. The trocar may also cause less tissue trauma than the larger hemostats

Three major complications occurred with TRO drains. All major complications in the TRO drain group were attributed to leakage in the tube or in the tube and Christmas Tree adapter connection. Air leakage at the connections to the Christmas Tree or three-way stopcock emphasizes the importance of securing connections and gentle and diligent manipulation during aspiration to avoid displacing or damaging the thoracostomy drain. It is not clear if leakage at the tube and Christmas Tree adapter junction in one case was the result of manipulation during placement or aspiration or a defect in that particular device. In cases in which an unexpected volume of air is aspirated, the drain should be clamped at the skin and reaspirated. Subsequent aspiration of air indicates a leak in the tube or connections proximal to the clamp.

Complication rates in this study were similar to previous reports, which ranged from 7 to 22%.^1,2,13 Reported complications not seen in the current study included accidental complete removal, blockage with fibrin clots, and gross clinical evidence of infection. Absence of these complications may be associated with the underlying diseases treated in the study and the short duration of tube placement for the majority of cases.² Lung tissue irritation, re-expansion pulmonary edema, phrenic nerve irritation, and neuropraxia have also been reported but were not seen in this study.¹

In both human and veterinary patients, thoracostomy drains have been associated with an increased risk of nosocomial infection after thoracic surgery.^5,14 Continuous suction minimizes the opportunities that bacteria have to proliferate in a static fluid column, theoretically reducing the risk of infection.^3,11 A JP drain can be used with a reservoir grenade for continuous suction of small volumes without the additional cost of an external continuous suction machine^g. No patients in this study were reported to develop infection in any of the drain types. Infection associated with thoracostomy drains is rare and may not be adequately represented in this study as a result of the small sample size.¹

In this study, the number of analgesic drugs, the rate of analgesic drug administration, or the addition of analgesia did not differ among thoracostomy tubes in the study. A pain score was not routinely used in our institution during the study period, which is a major limitation of this retrospective study. However, there were six animals with TRO tubes and two animals with JP drains that were subjectively assessed to have pain associated with the drain that resolved with additional medication and tube removal. In humans, chest tubes are associated with pain and fear during drain removal.^15,16 Human patients report that drains made of softer material such as silastic are more comfortable to wear and have removed than more rigid tubes.¹⁷ Soft tubes also appear less likely to cause tissue damage or to compress underlying structures.¹⁷ JP tubes are made of a silicone elastomer that is softer and more flexible than the polyvinyl chloride of traditional TRO tubes. Larger studies of similar cases assessed with pain scores would be necessary to evaluate this potential advantage. Given the purported pain associated with drain removal, additional analgesia should be considered when removing all thoracostomy drains.

This study had several limitations inherent to its retrospective nature. First, dogs were not randomly assigned to the JP tube, TRO tube, or GW thoracostomy drain. This led to differences in our populations of drain groups. Our conclusions with regard to pain associated with each thoracostomy drain are only based on on the addition of analgesic drugs and complications associated with perceived discomfort. Pain associated with surgery could not be differentiated from pain specifically associated with the thoracostomy drain. This assessment would be improved by undertaking a prospective study comparing pain scores, algometry, and activity level in dogs undergoing different types of thoracostomy. Closure of MS was performed with both suture and wire in this study. Surgical approach and closure may have affected postoperative pain; however, Pelsue et al. showed that there was no difference in postoperative pain between these groups.¹⁸ Finally, the small number of cats included in the current study may have made comparisons between species misleading.

Conclusion

We can accept our null hypothesis that JP drains are not associated with additional complications compared with other drains. JP drains can be considered as an alternative option to traditional TRO thoracostomy drains and GW thoracostomy drains. Prospective research is further needed to evaluate the potential beneficial effects of JP thoracostomy drains.