Abstract
Tracheostomies can be used to provide a patent airway in animals with upper airway obstruction but have been reported to be more difficult to manage in cats than in other animals. The purpose of this study is to retrospectively describe the indications, complications and outcome of cats undergoing tracheostomy. Twenty-three cats underwent tracheostomy for laryngeal mass (n=13), trauma (n=5) and upper airway swelling (n=5). Major and minor complications were recorded in 10 and 17 cats, respectively. Seventeen cats were discharged to home, four cats were euthanased and two cats died in hospital. Complications with stoma healing were reported in one cat. Of seven cats discharged with a permanent tracheostomy, one cat is alive and six cats survived at home for between 2 and 281 days. Although complications are common, temporary tracheostomies can be beneficial for conditions in which the underlying cause can be treated. Despite risk of occlusion, permanent tracheostomies can be effective palliative procedures for cats with severe upper airway disease.
Upper airway obstruction is a life-threatening event warranting immediate intervention. Reported causes of upper airway obstruction in cats include pharyngeal polyps, laryngospasm, trauma, foreign body and neoplasia (Tasker et al 1999). Temporary or permanent tracheostomies can be performed in order to bypass an upper airway obstruction. Procedures for performing temporary and permanent tracheostomies have been described and are routinely used in dogs and cats (Harvey and O'Brien 1982, Hedlund et al 1982, Hedlund et al 1988, Hedlund 1994, Colley et al 1999, Nelson 2003). Temporary tracheostomies are used to bypass the upper airway for a short period of time. Indications for a temporary tracheostomy include upper airway obstruction, trauma, neoplasia or ventilated patients (Colley et al 1999). Permanent tracheostomies are indicated for patients who require an alternate airway for an extended period of time. Such patients would include those with laryngeal tumours, severe secretory upper airway disease, laryngeal–tracheal resection or staged laryngeal reconstruction (Hedlund et al 1988). Studies have been done to document the complications, indications and outcome of tracheostomies in dogs and cats. The cats observed in these studies were reported to have a higher incidence of complications than has been reported in dogs and other large animals (Harvey and O'Brien 1982, Hedlund et al 1982, 1988). It has been theorised that cats with tracheostomies are at a higher risk of exudative occlusion of their tracheostomy site because of the development of thick airway secretions (Colley et al 1999). It has also been postulated that cats with tracheostomies are at a higher risk for sudden death than dogs due to a combination of increased mucous production and a smaller trachea which may not allow adequate ventilation around the tracheostomy tube in the event of an occlusion (Harvey and O'Brien 1982, Colley et al 1999). Of the studies that have been done looking at complications and outcome in patients with tracheostomies, the majority of the study subjects have been dogs (Harvey and O'Brien 1982, Hedlund et al 1988) and there is little data available regarding cats undergoing tracheostomy. The purpose of this study was to examine the records of cats undergoing temporary and permanent tracheostomies in order to describe indications, complications and outcome.
Methods and materials
The medical record files were searched and all cats that had permanent or temporary tracheostomies between 1998 and 2006 were retrospectively studied. Cats were excluded from the study if their records were incomplete or if the cat did not have a tracheostomy tube in place for at least 12 h. Records were evaluated for signalment, indication for tracheostomy, complications associated with the tracheostomy and outcome. Complications were broken out into major and minor complications. For the purpose of this study, a major complication was defined as dislodgement of the tracheostomy tube or an event causing total occlusion of the airway requiring immediate intervention. A minor complication was defined as a non-life-threatening event associated with the tracheostomy tube. Permanent tracheostomies were evaluated separately with regards to indications and outcome. Descriptive statistics were used as appropriate. χ2 and paired T-test analyses were used as appropriate to evaluate differences between groups with a P value of <0.05 considered significant.
Results
Signalment
Twenty-three cats were included in the study (Table 1). Cats ranged in age from 9 months to 18 years with a median of 11 years. Twelve cats were castrated males, one was an intact male and 10 were spayed females. Twenty-one cats were of mixed heritage with 16 domestic shorthair and five domestic longhairs. One each was an Abyssinian and a Himalayan.
Signalment, indication for tracheostomy and outcome of cats receiving a temporary tracheostomy
DSH/DLH=domestic shorthair/longhair, SF=spayed female, CM=castrated male, and MI=male intact.
Indications
The indications for tracheostomy were laryngeal mass (n=13), trauma (n=5), and upper airway swelling (n=5) (Table 2). Cats with head and neck trauma included three cats with severe bite wounds to the neck, one cat with motor vehicular trauma, and one cat with severe subcutaneous emphysema following an iatrogenic laryngeal tear during an attempt to place an esophagotomy tube. Severe upper airway swelling necessitated a tracheostomy in five cats including three cats following surgical interventions; one following an esophagotomy for removal of a linear metallic foreign body, one following bilateral bulla osteotomy surgery and one cat who developed iatrogenic laryngeal paralysis after a thyroidectomy. One cat had a severe upper respiratory infection with marked laryngitis and one cat had severe swelling following the aberrant migration of a Cuterebra larva through the soft palate. Of the 13 cats with a laryngeal mass, nine were neoplastic including six cats with squamous cell carcinoma, one cat with lymphoma, one cat with a round cell tumour and one cat with an undifferentiated carcinoma. Three cats had granulomatous laryngeal disease identified on histopathology. One cat had a cervical mass identified on a Computed Tomography (CT) scan but a biopsy of the mass was declined by the owner. The mean age of the cats with laryngeal neoplasia was 14.3±2.1 years, which was significantly older (P=0.007) than the cats with granulomatous laryngeal disease at 6.4±0.75 years. All cats had single-cannula, non-cuffed paediatric plastic tracheostomy tubes (Shiley Pediatric Tracheostomy Tube, Mallinckrodt Medical, Irvine, CA) placed. The tubes used ranged in size from 3.0 mm to 4.0 mm. All cats received antibiotics while hospitalised.
Indications for tracheostomy
Procedure
Four cats had tracheostomy tubes placed by a referring veterinarian. Seventeen cats had tracheostomy tubes placed by an Intensive Care Unit (ICU) resident or clinician and one cat had its tracheostomy tube placed by a board certified veterinary surgeon. All cats had stay sutures placed to facilitate opening of the stoma during tube replacement. Of the cats with a permanent tracheostomy, six cats had the procedure performed by a board certified veterinary surgeon and one cat had its permanent tracheostomy performed by an ICU resident. There was no significant difference in complications or outcome in regards to who performed the tracheostomy. All cats with a temporary or permanent tracheostomy were kept in the ICU and were monitored hourly for increased respiratory rate or effort. Tracheostomy sites were examined every 4 h and were cleaned or suctioned of accumulated debris, if indicated. A new tracheostomy tube, propofol and cotton tip applicators were hung on the cage door of all cats so as to be quickly available in the event of complete tube occlusion or tube dislodgement. Tracheostomy tubes were changed daily.
Complications
Major complications with temporary tracheostomies included tube occlusion and dislodgement and were recorded for 10 cats (Table 3). Total tube occlusion was recorded in six cats with a median of three events per cat (range: 1–5). The cause of occlusion for all six cats was excessive mucous secretions. All six of these cats had a tracheostomy performed for a laryngeal mass. Tube dislodgement was recorded in eight cats with a median of two events per cat (range: 1–3). Three of these cats had a tracheostomy performed for postoperative laryngeal oedema and five cats had a tracheostomy performed for a laryngeal mass. Five cats had episodes of both tube dislodgement and tube occlusion and all five of these cats had a tracheostomy performed for a laryngeal mass. Cats with a laryngeal mass were more likely (P=0.025) to have tube occlusion than cats without a laryngeal mass. All recorded complications of tube occlusion or dislodgement were promptly treated without any serious sequels.
Complications with temporary tracheotomies
Minor complications with temporary tracheostomies were recorded in 17 cats (Table 3). Minor complications included increased respiratory rate and respiratory effort associated with partial obstruction of the tracheostomy tube (n=14), hyperthermia [temperature>103°F (39.4°C)] (n=5), pneumomediastinum (n=3), subcutaneous emphysema (n=3), oedema at tracheostomy site (n=2), Horner's syndrome (n=1), iatrogenic laryngeal paralysis (n=1), cough (n=1), vomiting associated with tube suction (n=1) and dislodgement of stay sutures (n=1). Where noted in the medical records, all partial obstructions were reported as secondary to mucous secretions. Partial obstruction of the tracheostomy tube was resolved with suctioning or changing of the tracheostomy tube and hyperthermia resolved with therapy directed at the underlying condition. All other minor complications resolved without incidence.
Outcome
Cats had tracheostomy tubes in place for 1–11 days with a median of 3 days. Six cats had their temporary tracheostomy converted to a permanent tracheostomy after histopathology results were available. One cat initially had a permanent tracheostomy placed when the extent of the mass was visualised. One cat with lymphoma, one cat with squamous cell carcinoma and one cat with round cell neoplasia were euthanased when histopathology results were obtained. One cat with a cervical mass compressing the trachea was euthanased after a CT scan was performed. The owners declined a necropsy. One cat with severe bite wounds to the neck went into cardiac arrest and died after being hospitalised for 4 days. The death of this cat was not attributed to the tracheostomy. A second cat with bite wounds had progressive tracheal necrosis secondary to the wounds and was found dead in cage on the third day of hospitalisation. It was unclear if the cause of death was tracheostomy tube occlusion or tracheal collapse secondary to severe, progressive tracheal necrosis. The remaining 10 cats were discharged home and their tracheostomy sites were allowed to heal by second intention. Nine cats reported no complication with stoma healing. One cat had its stoma sutured closed 25 days after decannulation and reported no other complications.
Permanent tracheostomies
Permanent tracheostomies were placed in seven cats. Two permanent tracheostomies were placed in cats with granulomatous laryngeal disease. The remaining five cats with permanent tracheostomies all had carcinoma, four being squamous cell and one an undifferentiated carcinoma and all were discharged home. One cat with granulomatous laryngeal disease had its permanent tracheostomy reversed following a partial laryngectomy and is alive 1642 days with no further complications. A second cat with granulomatous laryngeal disease had an arytenoidectomy and survived at home 182 days after discharge. That cat was found dead of unknown causes at home and its owners declined a necropsy. The five cats with neoplasia survived at home 2–281 days after discharge. Two cats discharged home with a permanent tracheostomy died at home from tracheostomy site occlusion and three cats were euthanased due to anorexia/dysphagia (Table 4).
Signalment, tumour type and outcome of cats discharged home with a permanent tracheostomy
Discussion
The results of this study show that cats are at a high risk for complications with a tracheostomy. Over 40% of the cats studied had potentially life-threatening complications associated with tube occlusion or tube dislodgement and nearly two-thirds of the cats studied had episodes of increased respiratory rate and respiratory effort associated with partial occlusion of their tracheostomy tube. One cat died in hospital possibly due to complications from its tracheostomy. In comparison to a study which reported an overall complication rate of 50% in dogs and cats with a temporary tracheostomy, our study demonstrated a higher overall complication rate (87%) including more instances of tube occlusion and tube dislodgement than has been previously reported (Harvey and O'Brien 1982). The higher overall complication rate in our study may be due to the fact that our study looked exclusively at cats. The Harvey study did not break data out by species, but did note that cats and small dogs were more likely to have episodes of tube occlusion as compared to larger dogs. The majority of the cats in our study received a tracheostomy for a laryngeal mass whereas laryngeal mass was an indication for a tracheostomy in only a small number of patients in the Harvey study. In our study, most major complications and all episodes of total tube occlusion were reported in cats with a laryngeal mass. Excess secretions secondary to laryngeal mass have been reported (Saik et al 1986) and may have contributed to the higher complication rate in our study.
Cough, gagging and vomiting were not common complications in our study. However, coughing was reported in 26 animals (29.5%), and gagging and vomiting were reported in 31 animals (35%) in a prior study (Harvey and O'Brien 1982) in which metal tracheostomy tubes were exclusively used in their patients. The main advantage of a metal tracheostomy tube is the availability of an inner cannula with the smaller sized tubes. An inner cannula facilitates cleaning of tracheal secretions without disrupting the tracheostomy tube. Other reported advantages of a metal tracheostomy tube include a lower flow resistance and power of breathing as compared to a similar gauge plastic tube (Yung and Snowdon 1984). In human medicine, metal tracheostomy tubes have caused death in patients because of breakage (Otto and Davis 1985). Metal tracheostomy tubes, theoretically, may be more irritating to the tracheal mucosa than plastic tubes which tend to be lighter and more flexible. Decreased tracheal irritation with plastic tracheostomy tubes may be one explanation for the lower rate of coughing, gagging and vomiting associated with tracheostomy tubes reported in our study. The smaller plastic tubes, which are appropriately sized for cats, are not available with an inner cannula. Tubes must be suctioned or replaced in order to remove secretions. To the author's knowledge there are no studies which compare the use of metal versus plastic tracheostomy tubes in small or large animals and choice reflects clinician's preference.
In our study, all cats with a tracheostomy received antibiotics while in the hospital. The upper airway defence mechanisms, including removal of particulate matter, bacteria and other infectious pathogens, are bypassed in animals with a tracheostomy. Studies in human medicine have suggested that a tracheostomy may result in a contaminated wound thus prolonging healing of tissue and predisposing to stricture and scar formation (Sasaki et al 1979). A study in pigs demonstrated that tracheostomy could cause destruction of the tracheal epithelium and cilia leading to the arrest of mucus transport (Alexopoulos et al 1984). In our study, the rationale for antimicrobial therapy was not always clear from the medical record. Although five cats in our study developed a fever, no instance of infection of the tracheostomy site or bacterial contamination of the lower airway was reported.
The cats in our study with non-neoplastic disease had a good prognosis associated with resolution of their underlying disease as 91% were discharged to home with no further complications. Major and minor complications while the tracheostomy tubes were in place were common, but easily managed. One death may have been attributed to the temporary tracheostomy, however, this cat had severe tracheal necrosis secondary to bite wounds that may have complicated its outcome. Despite the risk of complications, temporary tracheostomies should be considered a viable option for the management of upper airway obstruction in cats.
Five of the seven cats undergoing a permanent tracheostomy were diagnosed with malignant laryngeal neoplasia. Primary laryngeal neoplasia in the cat is rare with the majority of laryngeal tumours being malignant (Saik et al 1986, Carlisle et al 1991). Long-term survival of cats with malignant laryngeal neoplasia is poor (Saik et al 1986, Carlisle et al 1991, Clifford and Sorenmo 2004). Surgical resection of a laryngeal mass can be performed but has been shown to be a palliative and not a curative measure (Saik et al 1986). Radiation and chemotherapy have been shown to be effective in controlling lymphoma in the cat and dog but there is little date regarding successful outcomes of radiation or chemotherapy for other laryngeal malignancies in cats (Evers et al 1994, Colley et al 1999, Withrow and MacEwen 2001). In conjunction with surgical resection, radiation or chemotherapy or as a sole means of palliative therapy, a permanent tracheostomy can be performed in order to establish a patent airway thus possibly increasing survival time in these patients.
Cats can be discharged home with a permanent tracheostomy. In this study, three of the seven cats discharged with a permanent tracheostomy died suddenly at home. Necropsy was not performed on these cats but it was presumed that the cats died of occlusion of their tracheostomy site either by secretions or by progression of their underlying disease.
The average length of hospitalisation after permanent tracheostomy was performed was 3 days in this study. In a previous study looking at permanent tracheostomies in cats and dogs, the majority of the patients were hospitalised for more than 5 days postoperatively (Hedlund et al 1988). These patients showed a gradual increase in the interval of postoperative cleaning of the tracheostoma during the first 7 days as tracheal secretions decreased. It could be postulated that the greatest risk for occlusion of the tracheostoma is within the first several days postoperative and that a longer hospitalisation with frequent monitoring may reduce the risk of occlusion after being discharged from the hospital. The majority of the cats with permanent tracheostomies in our study had malignant neoplasia and the median survival time was 42 days after being discharged home. A permanent tracheostomy was performed in these patients as a palliative procedure with the intent of making the cat comfortable at home for as long a period as possible. Although longer hospitalisation may have benefited the one cat that died at home 2 days after discharge, the majority of the cats did well at home during the first week after discharge. Keeping cats hospitalised longer may reduce the risk of occlusion of the tracheostoma at home but needs to be weighed against possible complications and costs (financial and emotional) associated with hospitalisation.
Conclusion
Temporary and permanent tracheostomies are effective procedures in cats. There is, however, a high complication rate associated with both procedures. Cats undergoing temporary or permanent tracheostomies initially require constant supervision because of the risk of airway obstruction. Temporary tracheostomies are beneficial for benign diseases or conditions in which the underlying cause can be treated. Permanent tracheostomies can be effective palliative procedures for cats with severe upper airway disease but there is a risk of sudden death after discharge.