Tracheostomy Techniques And Management

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Vol. 21, No. 1 January 1999

Refereed Peer Review

FOCAL POINT ★The likelihood of such complications as luminal stenosis, stomal stenosis, or occlusion occurring after tracheostomy can be minimized by using proper surgical technique and following correct postoperative management.

KEY FACTS ■ Cuffed tracheostomy tubes are only to be used for patients that require mechanical ventilation. ■ The type of tracheal incision is not a factor in the development of luminal stenosis. ■ The transverse flap technique is simple and allows easy removal and replacement of a tracheostomy tube. ■ Animals with permanent tracheostomies must avoid contact with dust, dirt, smoke, and water-related activities. ■ Laryngeal aspiration of food, water, or saliva has not been reported as a problem in animals.

Tracheostomy Techniques and Management Animal Specialty Group, Inc.

Auburn University

Patricia Colley, DVM Michael Huber, DVM, MS

Ralph Henderson, DVM, MS

ABSTRACT: Tracheostomy is an important tool for managing critically ill patients or patients with upper airway obstructions. Surgical techniques for temporary tracheostomy include transverse flap; transverse (horizontal), vertical, and inverted ventral wall flaps; and percutaneous (Seldinger) procedures. Serious complications can be prevented if practitioners apply their knowledge of tracheal anatomy, physiology, and wound healing and follow proper surgical technique and postoperative management procedures. Potential complications associated with permanent tracheostomy include skinfold occlusion and stomal stenosis.

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ommon emergency situations can arise when a patient’s airway quickly becomes compromised or a critically ill patient requires long-term ventilatory support or even permanent bypass of the upper airways. In these situations, surgical access to the trachea (tracheostomy) and proper placement of a tracheostomy tube are essential. Life-threatening complications can, however, develop after the presenting problem has been resolved. This article reviews the indications and techniques for temporary and permanent tracheostomy, tracheostomy tube maintenance, and potential complications.

INDICATIONS A temporary tracheostomy may be of short duration (6 or fewer hours) or intermediate duration (days to weeks). Short-duration tracheostomy is usually used during anesthesia for surgery of the oropharynx, especially if fracture repair requires restoration of correct dental occlusion. Intermediate-duration tracheostomy is usually used to manage upper airway obstruction, injury, or tracheal disruption.1–4 Tracheal obstruction may be secondary to stenosis, trauma, or neoplastic disease.1 Torsion, vascular anomalies, and peritracheal abscesses are causes of tracheal stenosis.1 In addition, trauma from luminal foreign bodies, wounds, and previous surgery may result in second-intention healing and stenosis. Laryngotracheal neoplasms are uncommon but may cause progressive obstruction of the airways during growth. The more common laryngotracheal neoplasms include mast cell tumor, oncocytoma, adenocarcinoma, chondrosarcoma, embryonic rhabdomyosarcoma, leiomyoma, lymphoma, osteochondroma, plasmacytoma, polyps, and squamous cell carcinoma.5,6 Temporary tracheostomy

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can be used to circumvent the upper airways while awaiting remission of obstruction during radiation therapy or during long-term ventilatory support of critically ill patients. Indications for a permanent tracheostomy include laryngeal paralysis or collapse, radiation therapy of the upper airways or oropharynx, laryngotracheal resections, staged laryngeal reconstruction, nasal neoplasia, or severe secretory respiratory disease.7,8 Permanent tracheostomy can be either lifelong or surgically closed after resolution of the primary disease.

NORMAL TRACHEAL ANATOMY The trachea is a semirigid, flexible air conduit that extends from the cricoid cartilage to the tracheal carina, where it divides to form the mainstem bronchi.9–12 The tracheal lumen is maintained by 35 to 45 C-shaped hyaline cartilage rings (the actual number varies by species, breed, and individual).12,13 The width of the average canine cartilage is 4 mm at its thickest point ventrally and tapers dorsally. The first tracheal ring, which is complete in dogs, resembles and is partially covered by the cricoid cartilage.13 The remaining rings are united longitudinally by interspersed 1-mm-wide fibroelastic annular ligaments.9,12 The tracheal rings are joined dorsally by the smooth transverse fibers of the tracheal muscle and, together with the mucosa, submucosa, and adventitia, form the dorsal tracheal membrane.9,10 The cervical trachea is bounded dorsally by the esophagus (cranially) and the longus colli muscles (caudally) and ventrally by the sternohyoid muscles (cranially) and sternocephalic and sternothyroid muscles (caudally).12,13 The trachea is bounded laterally on both sides by large neurovascular bundles that contain the vagosympathetic trunk, common carotid artery, internal jugular vein, and recurrent laryngeal nerve (which lies outside the common sheath on the left).12 The cervical portion of the trachea ends at the cranial mediastinum and becomes the thoracic trachea. The tracheal mucosa is composed of pseudostratified ciliated columnar epithelium, which contains basal, ciliated columnar, goblet, and nonciliated columnar cells.1,10,12,14 Most of the epithelium contains a ratio of approximately five ciliated cells per goblet cell.1,10 The submucosa contains elastic fibers, fat cells, and seromucinous tubular glands,10 the latter of which can secrete as much mucus as 40 goblet cells.1 The hyaline cartilage rings, annular ligaments, and tracheal muscle form the musculocartilaginous layer, whereas the adventitia is a loosely enclosing sleeve of fascia that blends the musculocartilaginous layer to surrounding connective tissue.1 The trachea is supplied by branches of the cranial thyroid, caudal thyroid, and bronchoesophageal arter-

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ies. The cranial and caudal thyroid arteries anastomose in the lateral pedicles and have branches that segmentally supply the ventral and lateral aspects of the trachea.1 The dorsal tracheal membrane is supplied by branches of the bronchoesophageal arteries.1 After the arterial branches have penetrated the annular ligaments, they arborize in the submucosa and communicate with a dense capillary net beneath the epithelium.13,15 Venous drainage occurs through the thyroid and internal jugular and bronchoesophageal veins.16 Lymphatic drainage continues to the deep cervical, cranial mediastinal, medial retropharyngeal, and tracheobronchial lymph nodes.1,17 The trachea is innervated by the sympathetic system via the sympathetic nerve trunk and the parasympathetic system via the recurrent laryngeal nerve.12,13 Sympathetic stimulation inhibits tracheal muscle contraction and glandular secretions, whereas parasympathetic stimulation has an opposing action.10

NORMAL TRACHEAL PHYSIOLOGY The primary purposes of the trachea are conduction of air to and from the lower airways and removal of particulate material from the bronchial tree.11 Patent flexibility is achieved during normal cervical movements by joining rigid cartilage rings with flexible annular ligaments.1,11 Although tracheal diameter changes slightly during normal respiration, the diameter of the lumen decreases by 50% during coughing.10 This dramatic reduction results from tracheal muscle contraction, which reduces dead space, increases the velocity of air, and is believed to aid in mucosal expulsion during the cough reflex.13 Inhaled particulate material and excessive bronchial secretions are cleared from the respiratory tract by the mucociliary escalator (a continuous layer of mucus produced by the goblet cells and seromucinous glands) and propelled toward the larynx by the ciliated epithelial cells at approximately 12.6 mm/min.1,10,11 The flow of mucus is most rapid in cats and younger dogs and is accelerated when warm, dry air is inspired.2 TRACHEAL WOUND HEALING Tracheal mucosa responds to irritation by increasing the production of mucus.10 Trauma to only the tracheal mucosa heals by migration, mitosis, and differentiation, which lead to complete epithelial regeneration.1,18 As early as 2 hours after injury, marginal epithelial cells lose their cilia, flatten, and begin migrating across the injury. These migrating epithelial cells, guided by the underlying elastic lamina, secrete enzymes that dissolve the fibrinous clot covering the denuded mucosa. Unlike in the epidermis, migration is limited to the marginal

TRACHEAL RINGS ■ CHANGES IN TRACHEAL DIAMETER ■ INCREASED MUCUS PRODUCTION

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ciliated columnar cells. Mismallest Shiley® double-lutosis within the basal and men tracheostomy tubea has columnar epithelia begins a 5-mm inner diameter and after cell migration; thus, a 9.4-mm outer diameter. the defect is covered with The smallest Shiley® singletransitional epithelium lumen tubea has a 3-mm inwithin 48 to 72 hours. Difner diameter and 4.5-mm ferentiation to ciliated or outer diameter. goblet cells begins within 96 Noncuffed tubes are used hours. Development of cilia in patients that require a byor differentiation to goblet pass of the upper airways, cells concludes mucosal rewhereas cuffed tracheFigure 1—The Shiley® tracheostomy tube (left) meets the critegeneration. ostomy tubes are only used ® Linear full-thickness in- ria for the ideal tracheostomy tube. (Right) Shiley tracheosto- in patients requiring mechmy tube with obturator (Mallinckrodt Medical TPI, Inc.). juries heal similarly if the anical ventilation. A trachetracheal mucosa remains in ostomy tube with a highapposition; however, loss of mucosa leads to gaps being volume, low-pressure cuff can minimize damage to the filled by granulation tissue, followed by wound contracheal mucosa and cartilage. traction and epithelialization (also known as second-inThe ideal tracheostomy tube should measure no largtention healing).3,10,19 Wound contraction results in a er than one half the diameter of the tracheal lumen, excertain degree of circular cicatrization. Therefore, healtend approximately six to seven tracheal rings, and be ing by second intention usually results in smaller lumimade of an autoclavable material (e.g., silicone, silver, nal diameters. or nylon) that is nonirritating to the trachea or be disResection and anastomosis procedures and traposable.4,28 The Shiley® tracheostomy tubea meets all of cheostomy invariably result in a degree of stenosis. Facthese requirements and is available in various sizes (Figtors promoting tracheal stenosis include excessive tenure 1) as either single lumen (or cannula) or double lusion at the surgical site, poor anastomotic apposition, men and cuffed or noncuffed. formation of granulation tissue, and infection.1,19–21 The Proper cuff inflation is very important to minimize tension exerted on an anastomotic suture line depends pressure necrosis and subsequent tracheal stenosis. Propon the amount of trachea resected and the relative elaser inflation controls the amount of air in the cuff to alticity of the trachea.1,19 The maximum tension before low optimum sealing of the airway.29 Such control, called tracheal disruption has been reported to be 1.7 kg for minimal occluding volume, is achieved in patients repuppies and 1.0 kg for adult dogs.22 Healing has been ceiving positive-pressure ventilation by gradually releasassociated with less inflammation and scar tissue if traing small increments of air from the cuff (0.25 to 0.5 ml) cheal cartilages are not compromised.23–25 Based on the until a small leak can be auscultated at the peak inspiradegree of luminal stenosis, many authors have concludtory pressure. This point represents the minimal occluded that the type of tracheal incision (transverse flap, ing volume, and cuff pressure should not be altered unhorizontal, or vertical) is not important in the developless problems develop with positive-pressure ventilation ment of stenosis.24–27 and airway pressure cannot be maintained.29 After the tracheostomy tube has been positioned, it should be seTRACHEOSTOMY TUBES cured by tying umbilical tape around the patient’s neck. Selection and Placement Monitoring and Care Proper selection and placement of tracheostomy Tracheostomy tubes require intensive care and monitubes can affect the success of the procedure. Veterinartoring to maintain patency and prevent life-threatening ians can select from a variety of sizes available as singlecomplications (e.g., tube dislodgment or occlusion or double-lumen and cuffed or noncuffed tubes. from blood and mucus). In some patients, the tube Single-lumen tubes must be removed and reinserted must be suctioned every 15 minutes during the immeeach time cleaning is required; double-lumen tubes are diate postoperative period whereas in others the tube easier to manage because the outer cannula remains in can be checked every 4 to 6 hours. Maintenance inplace and the inner cannula can be removed, cleaned, volves removing and cleaning the tube or inner cannuand replaced. Mucus can, however, still accumulate just la, suctioning the trachea, maintaining proper humidity distal to the inner cannula. Small tracheas cannot acaMallinckrodt Medical TPI, Inc., Irvine, California. commodate double-lumen tubes. For example, the TRACHEAL STENOSIS ■ TYPES OF TUBES ■ CUFF INFLATION ■ INTENSIVE CARE

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in the patient’s airways, and cleaning the stoma. Patients should undergo preoxygenation for at least 2 minutes before the procedure begins because tracheal suctioning can cause hypoxemia, which can lead to myocardial hypoxemia and premature ventricular contractions. In addition, because vagal stimulation from tracheal irritation can cause bradycardia, patients should have electrocardiographic monitoring during suctioning. Vagal stimulation can also cause gagging or vomiting; therefore, the trachea should not be suctioned immediately after a patient has eaten. Cats may require more frequent monitoring of the tube because they reportedly have more problems with the formation of thick mucus. During suctioning, the inner cannula of the tracheostomy tube or the entire single-lumen tube should be removed and soaked in 2% chlorhexidine solution and after suctioning, rinsed with sterile saline before being replaced. Using aseptic technique, a small, sterile suction catheter should be gently inserted through the outer cannula. Suctioning should not begin until the catheter is properly positioned within the tracheal lumen and should continue for no longer than 10 to 12 seconds. The catheter should then be rotated and withdrawn and oxygen immediately supplied to the patient. The procedure can be repeated if necessary but should never be continued in patients that show excessive discomfort or respiratory or cardiac changes. A low-friction catheter made from soft pliable tubing (e.g., suction catheter or red rubber catheter) should be used. All catheters are measured as 6, 8, 10, 12, 14, 16, or 18 Fr, which correspond to 2.0, 2.7, 3.3, 4.0, 4.7, 5.3, or 6.0 mm, respectively. The airways can be humidified by instilling sterile saline (0.2 ml/kg) into the tracheostomy tube every hour or by nebulization. Periodic forceful bilateral compression of the chest (coupage) is beneficial in clearing the lower airways of patients with excessive bronchial secretions. The bandage should be changed at least once a day and the site inspected for signs of infection. The area around the tube should be cleaned with a dilute solution of povidone–iodine or chlorhexidine and the bandage (soft roll gauze) replaced to minimize tube movement.

Removal The tracheostomy tube should be removed as soon as a normal airway has been established or when ventilation therapy is no longer required.30 Whether the patient can ventilate adequately without the tube can be determined by deflating the cuff (if present), occluding the tube to allow airflow to resume its normal passage, and monitor-

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ing ventilation.4 If air cannot flow around the tube and occlusion causes respiratory distress, a smaller tube should be inserted and the patient monitored. The tube can then be removed when the patient is breathing normally with the occluded tube. The tracheostomy site should be allowed to heal by second intention and exudate cleaned from the site during healing.4

Associated Complications Complications involving tracheostomy tubes include partial or complete obstruction, gagging and vomiting during suctioning, subcutaneous emphysema, and tracheal infection and necrosis.31 Acute complications also include hemorrhage, damage to peritracheal neurovascular structures, subcutaneous emphysema, pneumothorax, and pneumomediastinum.11,26,30 Tracheal irritation caused by the tube can lead to the formation of tracheoesophageal fistulas in the dorsal tracheal membrane and/or vascular erosions and hemorrhages.32 Luminal stenosis can cause a 5% to 75% reduction of the tracheal cross-sectional area. The tracheal mucosa is extremely sensitive to injury; mucosal erosions leading to ulceration and stricture can result after only a few hours if the endotracheal tube cuff is overinflated.33 Circumferential stenosis results from damage to the tracheal mucosa caused by inserting a tracheostomy tube that is too large or overinflating the cuff. Stenosis can also result from excessive tube movement within the tracheal lumen, which allows the tip of the tube to damage the tracheal mucosa or cartilage rings at the stoma. Several studies have shown that the type of tracheal incision plays a minor role in the development of luminal stenosis.24,26,27,34 The major factors contributing to luminal stenosis are the number of cartilage rings damaged or removed, amount of tube motion, length of time the tracheostomy tube was in place, and excessive cuff pressure.25,33,35 Tracheal resection and/or anastomosis is indicated to correct severe luminal stenosis. TEMPORARY TRACHEOSTOMY Temporary tracheostomy procedures involve the transverse flap34,36; transverse (horizontal),10,11,30,37,38 vertical,10,11,26,38 and inverted ventral wall flap26,38; and percutaneous (Seldinger)38 techniques. The lack of a permanent stoma with these techniques necessitates the use of a tracheostomy tube to maintain airway patency. The tracheostomy tube itself acts as a foreign body and causes inflammatory edema, increased mucus production, and decreased ciliary movement—all of which can lead to postoperative complications.10,12,13,32,37 In addition, partial or complete occlusion and dislodgment of the tracheostomy tube are common life-threatening complications.30

TUBE CARE ■ DAMAGE TO TRACHEAL MUCOSA ■ OCCLUSION

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When the tracheostomy Transverse Flap tube is no longer required, Advantages of the transthe transverse flap should be verse flap tracheostomy secured to its normal posiinclude easy removal and retion on the trachea using a placement of the trachesingle interrupted suture. ostomy tube by a single inThe remaining wound should dividual. In addition, the be allowed to heal by second procedure is technically simintention. ple34,36 (Figure 2). Although the original reThe trachea should be apport 34 describes relocating proached through a 10-cm the trachea to a more superventral cervical midline incificial plane by opposing the sion that begins at the A sternohyoid muscles dorsal cricoid cartilage and extends to the trachea, we did not caudally.34 The sternohyoid find this step necessary exmuscles should be retracted cept in patients with a deep laterally to expose the tratrachea or excessive cervical chea. After the recurrent laB skinfolds (e.g., bulldogs). ryngeal nerves have been located, the trachea should be isolated from the sternohy- Figure 2—The transverse flap technique involves (A) tracheal Transverse (Horizontal) The transverse tracheosoid muscles and the esopha- incision and placement of a flap handle suture and (B) placement of a tracheostomy tube. (Inset) Suture placement in the tomy consists of an incision gus without damaging these sternohyoid muscle dorsal to the trachea. through the annular liganerves. The sternohyoid ment between either the muscles should then be reapthird and fourth or the posed dorsal to the trachea fourth and fifth tracheal at the level of the second rings 4 (Figure 3). The apthrough seventh tracheal proach should be made rings in order to deviate the through a ventral midline trachea ventrally. incision that starts from the The transverse flap can be cricoid cartilage and extends made by incising the fifth caudally 4 to 6 cm. 7 The and sixth tracheal rings lonsternohyoid muscles should gitudinally 30 degrees to the be retracted laterally to exright of midline and then inpose the trachea and an incising transversely through cision made through the anthe annular ligaments benular ligament parallel to tween the fourth and fifth and between the third and and the sixth and seventh fourth or the fourth and tracheal rings. The subcutafifth tracheal rings. The inneous tissue and skin should cision should not extend be partially closed cranial more than half the circumand caudal to the site, allowference of the trachea.7 An ing at least one tracheal ring ellipse of cartilage can be caudal and cranial to the Figure 3—A completed transverse (horizontal) tracheostomy. excised from each tracheal flap to remain visible. (Inset) Location of the tracheal incision. cartilage adjacent to the inA nonabsorbable mattress cision to aid in tube placesuture should be placed ment and minimize tracheal irritation.39 through the flap and should engage the skin, subcutis, A nylon or polypropylene suture can be placed cartilage, and tracheal mucosa two thirds from the base around the cartilage ring immediately cranial and cauof the flap. The suture should be loosely tied, leaving dal to the incision and the ends cut long. The suture the ends long enough to move the flap when the tracan be used to open the tracheal incision when placing cheostomy tube is being removed or replaced. SIMPLE, EASY TRACHEOSTOMY ■ SURGICAL APPROACHES ■ SUTURE PLACEMENT

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or removing the tube. The sternohyoid muscles, subcutaneous tissue, and skin should be reapposed after tube placement. After the tracheostomy tube has been removed, the tracheal incision should be allowed to heal by second intention.

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second intention and found no significant difference. Anesthesia is not required if the flap is allowed to heal by second intention and therefore is ideal for patients that cannot tolerate additional anesthesia.

Percutaneous Tube Percutaneous tube tracheVertical ostomy (also known as the The vertical tracheostomy Seldinger technique) is curapproach is similar to that rently used in human medifor the transverse tracheostocine for critically ill and ventimy except vertical tralator-dependent patients. cheostomy involves a longThe technique is also used axis ventral midline incision to access the airways during through the third to fifth pediatric emergencies.40 Although it is not widely used tracheal rings (Figure 4). Figure 4—A completed vertical tracheostomy. (Inset) Locain veterinary medicine, perThis technique has not been tion of the tracheal incision. cutaneous tube tracheostoadvocated because the tramy may be useful when cheostomy tube can exert rapid access to the trachea is necessary. pressure on the everted rings, resulting in mucosal Lidocaine should be injected into the skin over the necrosis.2 site and the cricoid cartilage stabilized. After the annuInverted Ventral Wall Flap lar ligament between the second and third tracheal carThe inverted ventral wall flap can be either a U or V tilage rings has been located, a saline-filled syringe with shape and begins at the distal aspect of the fourth traa 14-gauge needle can be used to locate the tracheal lucheal ring and then extends cranially through the annumen (bubbles are aspirated when the needle is within lar ligament between the second and the lumen). The needle can serve as a third tracheal rings (Figure 5). After guide for making a 1-cm incision the tube has been placed, the flap along the lateral side of the needle on should be reflected outward and atthe ventral midline; a closed curved tached to the sternohyoid muscles hemostat should be placed through using either nylon or polypropylene the incision and into the lumen. 2 The hemostat should be opened to sutures. The sternohyoid muscles, spread the incision and should allow subcutaneous tissue, and skin should for tracheostomy tube insertion. then be reapposed. When the tracheostomy tube can PERMANENT TRACHEOSTOMY be removed, the trachea can either be A permanent tracheal stoma can resutured or allowed to heal by secbe created in the ventral tracheal wall ond intention. If the flap is to be reby suturing the tracheal mucosa to sutured to its original position in the the skin. The tracheostomy can be trachea, sharp dissection is used to either lifelong or surgically closed affree the flap from surrounding tister the primary disease has resolved. sue.38 The flap can also be freed by blunt dissection and returned to its Technique normal position in the trachea withUsing the technique described by out using sutures. Lulenski and BatHedlund,7,41 the trachea should be sakis 38 evaluated luminal stenosis when the flap was resutured and Figure 5—A completed inverted ventral approached through an 8- to 10-cm wall flap tracheostomy. when the flap was allowed to heal by ventral cervical midline incision by MUCOSAL NECROSIS ■ SELDINGER TECHNIQUE ■ PERMANENT STOMA

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starting at the cricoid cartiincludes the application of lage and extending the incipetrolatum ointment around A B sion caudally (Figure 6). the stoma to prevent the The trachea should be isomucus from adhering to the lated from the sternohyoid skin and obstructing the muscles and the recurrent stoma.4,8 The cleaning interval gradually increases to laryngeal nerves and esophaabout once a day after the gus protected. The sternofirst month. Owners also hyoid muscles should then need to clip the hair around be reapposed dorsal to the the stoma once or twice a trachea using several horimonth to prevent matting.4 zontal mattress sutures, moving the trachea to a more suComplications perficial plane, and reducing Skinfold occlusion of the the tension on the mucosa– tracheostoma is the most skin anastomosis. common long-term compliStarting at the second or cation after permanent trathird tracheal ring, a rectancheostomy.8 This complicagular segment of ventral tration occurs in animals with cheal wall that measures 3 or excessive skinfolds or sub4 tracheal rings in length and cutaneous fat that occlude one third of the tracheal dithe tracheostoma. Occluameter in width should be sion can also occur when the excised. 7,41 It is important C that the tracheal mucosa is neck is flexed. TracheostoD not penetrated. A similar segmies created more distally ment of skin on each side of Figure 6—Permanent tracheostomy involves (A) a tracheal in- along the trachea have an the tracheal defect can then cision, (B) incision in the tracheal mucosa, and (C) place- increased frequency of skinbe excised. If the animal has ment of a suture to achieve mucosa–skin apposition. (D) A fold occlusion. 8 To minimize skinfold occlusion, adloose skin or abundant sub- completed tracheostoma. ditional skin can be incised cutaneous fat, larger amounts before the skin–peritracheal of skin should be excised. fascia closure during the initial procedure. Skinfold ocClosure begins by apposing the skin to the peritraclusion can also be resolved by excising elliptic-shaped cheal fascia laterally and annular ligaments cranially pieces of skin on the right, left, and cranial aspect of and caudally using interrupted intradermal sutures. An I- or H-shaped incision should be made in the tracheal the tracheostoma as needed.8 A tracheostomy tube can mucosa and the edges sutured directly to the skin. The be inserted to provide temporary relief from the obremaining incision cranial and caudal to the stoma can struction. be closed routinely. Another serious complication is obstruction of the tracheostoma by mucous secretions, especially during Care the postoperative period. The owner should be advised The stoma should be inspected every 1 to 3 hours for that the animal must remain indoors in a clean enviaccumulation of mucus during the postoperative period ronment and not be subjected to dust, dirt, cigarette and cleaned when mucus begins to occlude the trasmoke, or burning wood. These environmental hazards cheostoma or causes increased respiratory effort.8 This can cause increased tracheobronchial secretions that can interval gradually increases from every 4 to 6 hours up result in stomal obstruction.8 As the tracheostomy site heals, some degree of stomal to every 12 hours or as necessary as healing continues stenosis (up to 30%) is normal. Excessive or progressive to progress.8 Owners must inspect the tracheostoma on a regular stenosis can result in hypoventilation. The degree of basis (every 4 to 6 hours during the first week) and stenosis can be minimized by using proper surgical carefully remove any mucous secretions using a clean technique with minimal manipulation of the tracheal moistened cottonball, swab, or gauze without disruptmucosa and by achieving precise mucosa–skin apposiing the suture line.4 Good tracheostoma hygiene also tion.4 Complete stenosis can occur if the stoma is too MUCOSAL–SKIN ANASTOMOSIS ■ MUCUS ACCUMULATION ■ SKINFOLD OCCLUSION

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small (only two to three cartilage rings long); tracheal collapse can occur if the stoma is too wide (more than one third the tracheal circumference) or too long (more than four cartilage rings).4 Preventing wound infection or self-trauma is also important in reducing tracheostomal stenosis and may require the use of hobbles or paw bandages.42 Preexisting problems, such as tracheal collapse or tracheomalacia, must be identified before permanent tracheostomy and corrected with an external ring prosthesis at the time of surgery.4 Excessive stomal stenosis requires surgical excision of the scar tissue and possibly enlargement of the original stoma without exceeding four rings in length and 30% of the circumference of the trachea. All cartilage should be covered by complete mucosal–skin apposition.42 Because cats may be more prone to develop thick mucus in the trachea, their postoperative recovery should be carefully monitored. They may also require more frequent cleaning of the stoma. After the stoma has healed, cats may experience problems with hair growing into the stoma; owners should be advised to keep the hair around the stoma clipped short. Laryngeal aspiration of food, water, or saliva has not been reported as a problem in animals. In one study, 73% of owners reported that their pets learned to forcefully expel mucus through the tracheostoma.8 Pulmonary infections also are not a problem if the lower respiratory tract is not compromised.4 Aspiration pneumonia or drowning can occur during bathing. In addition, owners should be advised that animals with a permanent tracheostomy should never be allowed to swim.

CONCLUSION Tracheostomy is an important part of surgical management for patients with upper airway disease or obstruction. Proper tube selection, cuff pressure, and postoperative management can help minimize the risks of life-threatening complications and stenosis developing after a temporary tracheostomy. Permanent tracheostomy can provide relief from upper airway distress and allow patients to live a near-normal lifestyle. The basic principles of proper tissue handling, wound care, and management result in minimal postoperative problems. About the Authors When this article was accepted for publication, Dr. Colley was affiliated with the Animal Specialty Group, Inc., Los Angeles, California; she is currently affiliated with Newport Harbor Animal Hospital in Costa Mesa, California. Dr. Huber, who is affiliated with the Animal Specialty Group, Inc. in Los Angeles, is a Diplomate of the American Col-

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lege of Veterinary Surgeons. Dr. Henderson is affiliated with the Department of Small Animal Surgery, College of Veterinary Medicine, Auburn University, Alabama; he is a Diplomate of the American College of Veterinary Surgeons and the American College of Veterinary Internal Medicine (Oncology).

REFERENCES 1. Tangner CH, Hedlund CS: Tracheal surgery in the dog— Part 1. Compend Contin Educ Pract Vet 5(8):599–603, 1983. 2. Nelson AW: Lower respiratory system, in Slatter DH (ed): Textbook of Small Animal Surgery. Philadelphia, WB Saunders Co, 1993, pp 777–804. 3. Fingland RB: Temporary tracheostomy, in Bonagura JD, Kirk RW (eds): Kirk’s Current Veterinary Therapy. XII. Small Animal Practice. Philadelphia, WB Saunders Co, 1995, pp 179–184. 4. Hedlund CS: Tracheostomy. Prob Vet Med 3(2):198–209, 1991. 5. Withrow SJ: Tumors of the respiratory system, in Withrow SJ, MacEwen EG (eds): Small Animal Clinical Oncology. Philadelphia, WB Saunders Co, 1996, pp 268–286. 6. Yanoff SR: Tracheal defect and embryonal rhabdomyosarcoma in a young dog. Can Vet J 37:172–173, 1996. 7. Hedlund CS: Surgery of the upper respiratory system, in Fossum TW (ed): Small Animal Surgery. St. Louis, The CV Mosby Co, 1997, pp 609–647. 8. Hedlund CS, Tangner CH, Waldron DR, et al: Permanent tracheostomy: Perioperative and long-term data from 34 cases. JAAHA 24(5):585–591, 1988. 9. Evans HE: The respiratory system, in Evans HE (ed): Miller’s Anatomy of the Dog. Philadelphia, WB Saunders Co, 1993, pp 463–493. 10. Hedlund CS: Surgical diseases of the trachea. Vet Clin North Am 17(2):301–332, 1987. 11. Bojrab MJ, Nafe LL: Tracheal reconstructive surgery. JAAHA 12(5):622–628, 1976. 12. Vasseur P: Surgery of the trachea. Vet Clin North Am 9(2):231– 243, 1979. 13. Grandage J, Richardson K: Functional anatomy, in Slatter DH (ed): Textbook of Small Animal Surgery. Philadelphia, WB Saunders Co, 1993, pp 692–708. 14. Dallman MJ, Cribb PH: Structural considerations in tracheal disease. Am J Vet Res 40(4):555–558, 1979. 15. Sobin SS, Frasher WG, Tremer HM, et al: The microcirculation of the tracheal mucosa. Angio 14(4):165–170, 1963. 16. Evans HE: Veins, in Evans HE (ed): Miller’s Anatomy of the Dog. Philadelphia, WB Saunders Co, 1993, pp 682–716. 17. Bezuidenhout AJ: The lymphatic system, in Evans HE (ed): Miller’s Anatomy of the Dog. Philadelphia, WB Saunders Co, 1993, pp 717–757. 18. Peacock EE: Epithelization and epithelial-mesenchymal interactions, in Wound Repair. Philadelphia, WB Saunders Co, 1984, pp 15–37. 19. Hedlund CS: Tracheal resection and reconstruction. Prob Vet Med 3(2):210–228, 1991. 20. Mendez-Picon G, Hutcher NE, Neifeld J, et al: Long-term study of tracheal growth after segmental resection in puppies. J Ped Surg 9(5):615–619, 1974. 21. Peacock EE: Healing and repair of viscera, in Wound Repair.

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