A 7-year-old spayed female 23.5-kg (51.7-lb) Spaniel-crossbred dog was referred to our veterinary medical teaching hospital for evaluation of stertorous breathing and inspiratory stridor, which were suspected to be secondary to a laryngeal mass or laryngeal paralysis. The referring veterinarian had evaluated the dog on the day before referral to our facility because of a 1-day duration of increased respiratory noise or snoring detected by the owner. A CBC was performed, and results were within the respective reference ranges. The dog was anesthetized by administration of propofol,a and a mass compressing the left arytenoid cartilage was detected. The dog was intubated, and a temporary cuffed tracheotomy tube was inserted transversely between tracheal rings on the midline in the midcervical region of the trachea. The dog recovered from anesthesia without complication and was administered dexamethasone sodium phosphate, IV. The next day, the dog was sedated for examination, which revealed that the mass was noticeably smaller. Laryngeal paralysis was suspected, and the dog was immediately referred to our veterinary medical teaching hospital for further evaluation.
Physical examination revealed that the dog was panting and appeared anxious. The tracheotomy site was evaluated, and adequate air movement was detected through the lumen of the temporary tracheotomy tube. A small amount of blood-tinged discharge was evident around and within the lumen; the discharge was removed by aspiration. The tracheotomy tube did not have an internal canula, which limited further inspection. Thoracic auscultation revealed typical lung sounds in all lung fields, and auscultation of the heart also revealed typical sounds with a heart rate of 120 beats/min. Results for the remainder of the physical examination were unremarkable.
The initial diagnostic plan included serum biochemical analysis and urinalysis. Serum biochemical abnormalities included hypercholesterolemia (386 mg/dL; reference range, 138 to 317 mg/dL); hyperbilirubinemia (0.3 mg/dL; reference range, 0 to 0.2 mg/dL); and an increase in activity of alkaline phosphatase (946 U/L; reference range, 14 to 120 U/L), alanine transaminase (154 U/L; reference range, 16 to 73 U/L), and creatine kinase (2,390 U/L; reference range, 48 to 380 U/L). Thoracic and cervical radiography were performed, which revealed mild alveolar infiltrates in the cranial lung lobes. The cause of this pattern was unknown, but it was consistent with inhalation of hemorrhage from the previously placed tracheotomy tube.
To further examine the larynx, anesthesia was induced in the dog by administration of propofol (5 mg/kg [2.3 mg/ lb], IV). A 2 × 2-cm nodular mass was visible on the lateral aspect of the epiglottis. The mass incorporated the left arytenoid cartilage and impaired its movement. Because there was a cuffed tracheotomy tube in place, a biopsy specimen of the mass was obtained, and impressions for cytologic evaluation were obtained by touching the surface of the specimen to a slide. Cytologic interpretation was septic suppurative inflammation; small, intracellular, rod-shaped bacteria were detected. Histologic examination of the biopsy specimen confirmed the cytologic diagnosis. There was no evidence of neoplasia. Fine-needle aspiration was used to obtain a specimen for microbial culture, but it yielded no growth.
Throughout the procedures, decreased air movement was evident through the tracheotomy tube, and there was decreased compliance while ventilating the dog with a nonrebreathing anesthesia system. Thus, once minor hemorrhage was controlled at the biopsy site, the temporary tracheotomy tube was replaced with a cuffed, cannulated tracheotomy tube.b A large thrombus was found on the distal end of the temporary tracheotomy tube. The thrombus obstructed approximately 90% of the tube lumen. Dexamethasone sodium phosphatec (0.1 mg/kg [0.045 mg/lb], IV) was administered to decrease inflammation. Antimicrobial treatment with ampicillin-sulbactamd (22 mg/kg [10 mg/lb], IV, q 8 h) and enrofloxacine (10 mg/kg [4.5 mg/lb], IV, q 24 h) was initiated after the cytologic diagnosis of septic inflammation was made.
The following morning, the dog had an obstructive breathing pattern. Decreased lung sounds were auscultated in all lung fields, and there was decreased air movement through the lumen of the tracheotomy tube. Mucous membranes were pink and moist, and pulse oximetry revealed an oxygen saturation value of 92%. Cervical and thoracic radiography were performed to evaluate the potential causes of the decreased air movement. Examination of lateral radiographic views revealed an intraluminal soft tissue opacity in the distal portion of the trachea. The cuffed tracheotomy tube appeared to be in an appropriate position and was visible proximal to the soft tissue opacity. A mild alveolar pattern was evident in the cranial lung fields.
On the basis of the severity of clinical signs and radiographic evidence of a mass or foreign body in the trachea, the dog was anesthetized by IV administration of a continuous rate infusion of propofol for immediate tracheoscopy. The tracheotomy tube was removed, and a 10-F red-rubber catheter was inserted through the tracheal incision and advanced in the trachea for provision of oxygen. A video-gastroscopef was used to examine the oral cavity. The previously detected mass in the epiglottal-arytenoid cartilage area was substantially smaller. The gastroscope was then introduced into the trachea and advanced to the level of the obstruction. A mass that appeared to be obstructing most of the tracheal lumen was identified (Figure 1). The mass was dark red, and hair was incorporated within the structure of the mass. Small rat-tooth forceps were advanced through the biopsy port of the gastroscope to remove the mass. Unfortunately, the mass was friable, and only small pieces could be removed with the forceps. A Fogarty catheterg was then introduced through the tracheal stoma and advanced past the mass, as determined by observation with the gastroscope. The balloon was inflated and retracted retrograde in the trachea to dislodge the mass. The biopsy forceps of the gastroscope were then used to remove the mass. The trachea was subsequently examined to the carina, and no remaining mass or foreign material was detected.
Videogastroscopic view of a mass in the lumen of the trachea of a 7-year-old dog with stertorous breathing and inspiratory stridor. The mass is an organized thrombus that contains hair and plant material. Notice the Fogarty catheter on the left side.
Citation: Journal of the American Veterinary Medical Association 233, 5; 10.2460/javma.233.5.758
Videogastroscopic view of a mass in the lumen of the trachea of a 7-year-old dog with stertorous breathing and inspiratory stridor. The mass is an organized thrombus that contains hair and plant material. Notice the Fogarty catheter on the left side.
Citation: Journal of the American Veterinary Medical Association 233, 5; 10.2460/javma.233.5.758
Videogastroscopic view of a mass in the lumen of the trachea of a 7-year-old dog with stertorous breathing and inspiratory stridor. The mass is an organized thrombus that contains hair and plant material. Notice the Fogarty catheter on the left side.
Citation: Journal of the American Veterinary Medical Association 233, 5; 10.2460/javma.233.5.758
The mass was submitted for histologic examination, which revealed an organized thrombus that contained hair and plant material. Because of trauma associated with repeated insertion of the gastroscope through the larynx, another dose of dexamethasone sodium phosphate was administered. A new temporary cuffed tracheotomy tube was placed through the original tracheal incision made by the referring veterinarian, and the cuff was inflated. Radiographs were taken after completion of the procedures. Examination revealed resolution of the tracheal soft tissue opacity in the distal portion of the trachea.
The following morning, results of physical examination were unremarkable. There was appropriate air movement through the tracheotomy tube, and auscultation revealed adequate sounds in all lung fields. Later that day (approx 30 hours after the initial thrombus was removed from the dog's trachea), the dog had another episode of respiratory distress. The dog became cyanotic and vomited and urinated in the cage. It was apparent that the tracheotomy tube was obstructed, and a suction catheter was advanced through the tracheotomy in an attempt to dislodge or remove the obstruction. When the suction tube was removed, blood was evident on it. The dog regained air movement through the trachea, and cyanosis resolved. Examination of lateral cervical and thoracic radiographic views indicated another soft tissue opacity in the distal portion of the trachea at approximately the same location as the previous soft tissue opacity, and a diffuse reticulonodular-to-alveolar pattern was evident in all lung fields (Figure 2).
Lateral thoracic radiographic view of the dog in Figure 1. Notice the diffuse reticulonodular-to-alveolar pattern in the lungs and a soft tissue opacity (arrow) in the trachea distal to the tracheotomy tube.
Citation: Journal of the American Veterinary Medical Association 233, 5; 10.2460/javma.233.5.758
Lateral thoracic radiographic view of the dog in Figure 1. Notice the diffuse reticulonodular-to-alveolar pattern in the lungs and a soft tissue opacity (arrow) in the trachea distal to the tracheotomy tube.
Citation: Journal of the American Veterinary Medical Association 233, 5; 10.2460/javma.233.5.758
Lateral thoracic radiographic view of the dog in Figure 1. Notice the diffuse reticulonodular-to-alveolar pattern in the lungs and a soft tissue opacity (arrow) in the trachea distal to the tracheotomy tube.
Citation: Journal of the American Veterinary Medical Association 233, 5; 10.2460/javma.233.5.758
The dog was immediately anesthetized again by administration of a constant rate infusion of propofol, and a red-rubber tube was advanced through the stoma at the site of the removed tracheotomy tube to enable administration of oxygen. The videogastroscope was advanced via the oral cavity into the trachea to allow examination of the suspected thrombus. To obtain a better view, the red-rubber catheter was retracted, and the thrombus was dislodged. Grasping forceps were then introduced via the biopsy channel of the videogastroscope, and the thrombus was removed. On the basis of the assumption that the continued hemorrhage was a complication at the tracheotomy tube site and the fact the laryngeal mass was greatly reduced in size, it was decided that the tracheotomy tube would not be replaced.
A coagulation panel was performed, and prothrombin time, partial thromboplastin time, and platelet count were within the respective reference ranges. Buccal mucosal bleeding time was also determined, and it also was within the reference range (2 minutes; reference range, < 4 minutes). An arterial blood sample was obtained while the dog was breathing room air during recovery from anesthesia. Blood gas analysis revealed PaO2 of 69 mm Hg, PaCO2 of 49 mm Hg, and alveolar-arterial gradient of 19.5. The dog recovered well from anesthesia and did not have any additional respiratory complications.
The following morning, the dog appeared to be resting comfortably and results of physical examination were unremarkable. Thoracic radiography was performed and revealed mild pneumomediastinum, which was assumed to be attributable to air dissection along fascial planes from the previous tracheotomy site. An arterial blood sample was obtained, and blood gas analysis revealed PaO2 of 82 mm Hg, PaCO2 of 37 mm Hg, and alveolar-arterial gradient of 14.5. The dog was discharged to the owner with instructions to continue oral administration of antimicrobials.
Discussion
To the authors' knowledge, airway obstruction resulting from an intraluminal thrombus has not been reported in the veterinary literature. There have been reports of an intramural tracheal hematoma in a dog secondary to fighting with another dog1 and intraluminal hemorrhage secondary to anticoagulant rodenticide intoxication in a dog.2
Numerous reports3 exist of tracheal and endobronchial thrombi causing life-threatening ventilatory impairment in humans. These conditions are secondary to complications of respiratory and cardiac disease as well as mucosal damage from tracheotomy placement, transbronchial biopsy, bronchoalveolar lavage, and suction-catheter manipulation.3 In affected humans, 70% reportedly have evidence of hemoptysis preceding formation of these thrombi, and 30% of occult thrombi are associated with prolonged mechanical ventilation or tracheostomy placement.3 In contrast to the situation in humans, the dog reported here had a tracheal incision for a temporary tracheotomy tube, rather than creation of a stoma for a tracheostomy tube. The most likely cause for the formation of the thrombi in this dog was local hemorrhage from the surrounding musculature and soft tissues during initial placement of the temporary tracheotomy tube and then continued hemorrhage that resulted from manipulation and removal of the initial thrombus. The initial thrombus contained hair and plant material. This supports the possibility that a foreign body caused trauma to the larynx, which resulted in an abscess and the initial clinical signs. We believe that the second intraluminal thrombus was attributable to iatrogenically induced hemorrhage from the surrounding musculature. The diffuse reticulonodular-to-alveolar pattern detected during examination of thoracic radiographs taken prior to thrombus removal was attributed to aspiration of blood products secondary to the tracheal hemorrhage. This pattern is typically reflective of primary pulmonary disease, but in this dog, it resolved within 24 hours after tracheotomy tube removal.
Several treatments have been used in humans with tracheal and bronchial thrombi. These include provision of supportive care, removal of an endotracheal or tracheostomy tube, use of a flexible or rigid bronchoscope, administration of endobronchial streptokinase, or a combination of these methods. In 1 report4 of 3 humans with thrombi, a technique for dislodging a thrombus with a Fogarty cardiology balloon catheter is described. The site of the thrombi in these patients ranged from the distal portion of the trachea to the left and right mainstem bronchi. In the dog reported here, we were not able to adequately remove the initial organized thrombus by use of biopsy and grasping forceps passed through the gastroscope. However, we were able to use a Fogarty catheter to dislodge the thrombus and facilitate removal. The catheter was small enough to pass along the side of the thrombus without pushing the thrombus further into the trachea. The balloon on the Fogarty catheter was inflated distal to the thrombus, and we were able to easily dislodge the thrombus by retrograde movement of the catheter. We believe this can be a practical and useful method for removal of a foreign body, thrombus, or mass in patients with an intratracheal obstruction.
Ben Venue Laboratories, Bedford, Ohio.
Shiley tracheotomy tube, Tyco Healthcare, Pleasanton, Calif.
Dexamethasone SP, American Regent Corp, Shirley, NY.
Ampicillin and sulbactam, Sandoz, Princeton, NJ.
Baytril, Bayer Health Care, Animal Health Division, Shawnee Mission, Kan.
Olympus GIF XP160 video gastroscope, Olympus American, Center Valley, Pa.
Fogarty embolectomy catheter, Baxter, Irvine, Calif.
References
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Arney KL, Judson MA, Sahn SA. Airway obstruction arising from blood clot. Three reports and a review of the literature. Chest 1999;115:293–300.
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Allen RP, Siefkin AD. Emergency airway clot removal in acute hemorrhagic respiratory failure. Crit Care Med 1987;15:985–986.
