Retrospective Evaluation of the Use and Complications of Small-Bore Wire-Guided Thoracostomy Tubes in Dogs and Cats: 156 Cases (2007-2019).

Background: Small-bore wire-guided thoracostomy tubes (SBWGTT) are commonly used in small animals for management of pleural space disease. We aimed to evaluate the indications, placement locations, types of complications, and complication rate of small-bore wire-guided thoracostomy tube placements in dogs and cats in a university setting. Methods: Electronic medical records of patients that underwent SBWGTT placement were reviewed. Signalment, disease, outcome, indication for thoracostomy tube, placement location, number of attempts, diagnostic imaging, number, and type (insertional, technical, and infectious) of complications were recorded. Logistic regression analysis was performed to determine risk factors for complications. Results: A hundred fifty-six cases were identified between 2007 and 2019. Traumatic pneumothorax (33%), pyothorax (25%), and spontaneous pneumothorax (16%) were the most common indications for placement of a SBWGTT. Complications developed in 50 cases (32%). Technical and insertional complications accounted for 21.7% and 14.1% of all cases. Infectious complications were rare with 3.1% of all cases. Pneumothorax (19%), soft tissue swelling at insertion site (14%), and kinking of the chest tube (13%) were most common. Accidental lung perforation was reported in 5/50 complications (7%). Multiple chest tube placement attempts were associated with complications (OR = 6.01 CI: 2.13 to 16.93 p = 0.0007). Conclusions: Complications of SBWGTT placement occurred in one third of cases. Serious complications such as accidental lung perforation was reported in two cases. Complications were associated with number of attempts.

Distribution and Magnitude of Regional Volumetric Lung Strain and Its Modification by PEEP in Healthy Anesthetized and Mechanically Ventilated Dogs.

The present study describes the magnitude and spatial distribution of lung strain in healthy anesthetized, mechanically ventilated dogs with and without positive end-expiratory pressure (PEEP). Total lung strain (LSTOTAL) has a dynamic (LSDYNAMIC) and a static (LSSTATIC) component. Due to lung heterogeneity, global lung strain may not accurately represent regional total tissue lung strain (TSTOTAL), which may also be described by a regional dynamic (TSDYNAMIC) and static (TSSTATIC) component. Six healthy anesthetized beagles (12.4 ± 1.4 kg body weight) were placed in dorsal recumbency and ventilated with a tidal volume of 15 ml/kg, respiratory rate of 15 bpm, and zero end-expiratory pressure (ZEEP). Respiratory system mechanics and full thoracic end-expiratory and end-inspiratory CT scan images were obtained at ZEEP. Thereafter, a PEEP of 5 cmH2O was set and respiratory system mechanics measurements and end-expiratory and end-inspiratory images were repeated. Computed lung volumes from CT scans were used to evaluate the global LSTOTAL, LSDYNAMIC, and LSSTATIC during PEEP. During ZEEP, LSSTATIC was assumed zero; therefore, LSTOTAL was the same as LSDYNAMIC. Image segmentation was applied to CT images to obtain maps of regional TSTOTAL, TSDYNAMIC, and TSSTATIC during PEEP, and TSDYNAMIC during ZEEP. Compliance increased (p = 0.013) and driving pressure decreased (p = 0.043) during PEEP. PEEP increased the end-expiratory lung volume (p < 0.001) and significantly reduced global LSDYNAMIC (33.4 ± 6.4% during ZEEP, 24.0 ± 4.6% during PEEP, p = 0.032). LSSTATIC by PEEP was larger than the reduction in LSDYNAMIC; therefore, LSTOTAL at PEEP was larger than LSDYNAMIC at ZEEP (p = 0.005). There was marked topographic heterogeneity of regional strains. PEEP induced a significant reduction in TSDYNAMIC in all lung regions (p < 0.05). Similar to global findings, PEEP-induced TSSTATIC was larger than the reduction in TSDYNAMIC; therefore, PEEP-induced TSTOTAL was larger than TSDYNAMIC at ZEEP. In conclusion, PEEP reduced both global and regional estimates of dynamic strain, but induced a large static strain. Given that lung injury has been mostly associated with tidal deformation, limiting dynamic strain may be an important clinical target in healthy and diseased lungs, but this requires further study.

In vitro effect of 20% N-acetylcysteine on the viscosity of normal canine bile.

OBJECTIVE To evaluate the in vitro effect of 20% N-acetylcysteine (NAC) on the viscosity of normal canine bile. ANIMALS Bile samples obtained from 10 adult dogs euthanized for reasons unrelated to biliary disease. PROCEDURES Each sample was centrifuged to remove particulates, then divided into 3 aliquots. One aliquot remained untreated (control). Each of the other aliquots was diluted 1:4 with 20% NAC or sterile water. The viscosity of all samples was measured with a rotational viscometer at 25°C. Viscosity of control samples was measured immediately after centrifugation and at 1 and 24 hours after treatment application to the diluted samples. Viscosity of diluted samples was measured at 1 and 24 hours after treatment application. RESULTS Mean viscosity differed significantly among the 3 groups at both 1 and 24 hours after treatment application. Relative to control samples, the addition of NAC and sterile water decreased the viscosity by approximately 3.35 mPa·s (95% confidence interval [CI], 1.58 to 5.12 mPa·s) and 2.74 mPa·s (95% CI, 1.33 to 4.14 mPa·s), respectively. Mean viscosity of the NAC-treated samples was approximately 0.61 mPa·s (95% CI, 0.21 to 1.01 mPa·s) less than that for the sterile water-treated samples. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that in vitro dilution of canine bile 1:4 with 20% NAC significantly decreased the viscosity of the resulting mixture. Further research is necessary to determine whether NAC is a safe and effective noninvasive treatment for dogs with persistent biliary sludge or gallbladder mucoceles.