Retrospective evaluation of small-bore chest drain versus trocar-type thoracostomy tube for the management of pyothorax in cats.

Thoracostomy tubes are routinely applied for air and fluid removal from the pleural space in cats. Recently, small-bore wire guided chest drains, inserted with a modified Seldinger technique, were proposed for management of pleural space disease in cats (1,2). The aim of this retrospective study is to evaluate the performance of a small-bore (14 Ga, 2 mm) wire guided chest drain (MILA® International Inc.; SBCD) compared to a (12 Fr, 4 mm) traditional trocar-type chest drain (Redax® S.p.a., TTCD) for the management of pleural effusion secondary to pyothorax in cats. Cats with a documented pleural septic effusion, treated at least initially with a thoracostomy drain, between June 2008 and March 2017 were included. Two groups were created according to the type of drain applied: traditional TTCD inserted in the thorax with pressure and a SBCD inserted with a Seldinger technique. Clinical data relative to the application of the drain including complications, length of time in use, need of analgesia, surgical exploration and outcome were recorded.Twenty-one cats with a confirmed diagnosis of pyothorax were included in the study: SBCD was positioned in 8 cats and TTCD in the remaining 13 cats. Bilateral pleural septic effusion was prevalent in both groups. In the TTCD group, general anesthesia was required for the procedure and the chest drains were positioned bilaterally in 9/13 cases (69%). The application of the SBCD necessitated a mild sedation and was monolateral in 8/9 cats (89%). Post-operative analgesia was significantly different between the two groups with a more frequent requirement of rescue therapy with methadone in the TTCD one (p=0.02). No significant differences in the frequency of complications (pneumothorax, malpositioning) were reported during application, however an episode of cardiac arrest occurred in TTCD group. Obstruciotn occurred in both groups during the use of toracostomy tubes. The number of cats who underwent surgery was not statistically different between the two groups. No deaths were reported in the SBCD group, while 6/13 cats (46%) died in the TTCD group (p<0.05).SBCD can be positionated easily by a Seldinger technique with only mild sedation and appears to be more confortable. Moreover the possibility to apply the drain monolaterally can further decrease the time needed for the application, without reducing their efficacy. The use of the SBCD was only recently introduced in our hospital. Due to the retrospective nature of the study, we could not exclude that a global improvement in the care of the patients or the presence of a more severe clinical condition in the group treated with TTCD, could have influenced the different outcome between the 2 groups. Further prospective studies are necessary to evaluate the impact of the SBCD on the outcome of the feline patients with pyothorax. In conclusion the SBCD appears easier to place, more confortable for the patient and efficacious in removing dense matherial form the thorax; thus, its use for the management of pleural effusion secondary to pyothorax in cats is warranted.