Background

Salivary fistulae are most commonly associated with major onco-logic resections of the upper aerodigestive tract, but can occur when resecting benign disease, such as the closure for the resection of a Zenker's diverticulum. All salivary fistulae, whether pharyngocutaneous or orocutaneous, present similar management problems. The best time to manage a fistula is by prevention at the primary operation.1 Operative technique that avoids excessive tissue destruction is the first step, along with ensuring that the mucosal suture line be watertight. For the mucosal suture, interrupted Vicryl (polyglactic acid) or silk sutures are used. After total laryngectomy, closure of mucosa is achieved using an inverting suture of polyglactic acid which maintains integrity during wound repair. Soylu et al.2 showed a statistically significant reduction in the incidence of pharyngocutaneous fistula when this suture was used for closure (8.6%) compared with catgut (24%).

At the completion of mucosal closure in total laryngectomy and laryngopharyngectomy, a test of the integrity of the closure is performed by filling the neopharynx with saline, noting leaks, and repairing them with additional sutures for closure. It makes sense that a saline leak at the time of operation will produce a salivary leak postoperatively. Tension on the suture line should be minimized, and a two- to three-layer closure can usually be achieved by closing the fascial and muscle layers overlying the repair. In the case of a total laryngectomy, at least a two-layer repair is favored (i.e., submucosa and pharyngobasilar fascia). When enough constrictor muscle is present on one side, it can be used to bolster the line of closure by securing it across the suture line but not providing pharyngeal constriction. This provides an additional layer of closure without reuniting the inferior constrictor and narrowing the neopharynx, affecting swallowing and tracheo esophageal puncture speech. The larger the tumor and the resection, the greater the potential for tension on the mucosal closure.3 Several authors have demonstrated an increased incidence of fistula as the amount of mucosa resected increases, particularly in pyriform sinus cancers.4-6 Closure in these cases results in increased tension on the suture line as well as increased intraluminal pressure. To avoid these problems, a vascularized flap may be necessary to provide an adequately sized neopharynx.

The choice of flap depends on the available resources and surgical capabilities. Whether using a pectoralis major myocu-taneous flap, radial forearm flap, or jejunal free flap, it is imperative that the flap is inset securely. In the oral cavity, when a flap is inset adjoining the mandible, additional support can be provided by anchoring the flap to any remaining teeth or to the mandible itself, if the patient is edentulous, to provide flap support and reduce suture line tension. When a modified radical or radical neck dissection has been performed in conjunction with a pharyngeal resection, coverage of the carotid artery by a dermal graft or sternomastoid or levator scapulae muscle should be considered as a prophylactic maneuver to reduce the risk of carotid blow-out in the event of a fistula developing.7 Suction drainage is used to minimize fluid beneath the skin flaps and control the spread of saliva if a fistula develops.8 The drains should not be placed on the mucosal closure lines but should lie in close proximity.

The type of neck incision used is important. Trifurcations should be avoided, since these points have the poorest blood supply, predisposing to wound breakdown. Ifa fistula develops, it will appear at these sites.4'9 If necessary, the modified Schobinger incision places the trifurcation along the anterior trapezius border, away from the carotid artery. The use of apron incisions or McFee incisions is our preference to avoid this problem.

A wound infection is always present when a fistula occurs, due to contamination of the wound by saliva. Perioperative antibiotics should always be used when mucosa is entered, since their use has long been proven effective in decreasing the incidence of wound infection when the pharynx is entered.10,11

The nutritional status of the patient affects all major surgery, with starvation, trauma, sepsis, and malignancy all resulting in a catabolic state.12 In these situations, wound healing may be impaired and patients are predisposed to the development of complications such as fistulae. Although a precise methodology for quantifying malnutrition is not available, any history of significant weight loss with a patient who appears cachectic on physical exam, with a low albumin and pre-albu-min, makes it peremptory to consider hyperalimentation, even before surgery, to minimize postoperative complications. In addition, thyroid-stimulating hormone (TSH) should be checked to evaluate for hypothyroidism, which is especially important for salvage surgery following radical radiotherapy.

Several authors have found that low postoperative hemoglobin is associated with the development of fistulae,5'13'14 although few have offered an explanation for this finding. Frederickson and Haight15 suggest that the decrease in blood volume, which is reflected by the lowered hemoglobin, results in lowered wound oxygen tension, which has been shown to increase bacterial colonization of wounds and slow the rate of healing.

The impact of radiotherapy as a cause of fistula formation is still a topic of considerable debate. Radiotherapy is known to result in endothelial fibrosis with reduced tissue blood supply.16 McCombe and Jones17 demonstrated an incidence of fistulae of 39% in salvage laryngectomy and only 4% in the group having laryngectomy as the primary treatment, though others have been unable to demonstrate a statistical difference between the rate of fistulae in irradiated and nonirradiated patients.7,13,18

There is no common system for classifying salivary fistulae, and most authors divide them into small, medium, and large.3,19,20 Small and medium fistulae generally heal with local wound care.4,5,20 The exception to this is medium-size fistulae in an irradiated wound, which will usually require surgical intervention.19 Large fistulae with loss of skin will always require surgical repair with a flap.3 The timing of closure is also debated. Most investigators recommend waiting 4 to 6 weeks, a time when the wound will be clean and granulating.14,20,21 Earlier repair or intervention is mandatory when the carotid artery is exposed,3,22 if not for wound closure, at least for carotid protection. Small fistulae are usually packed with ribbon gauze. Dedo et al.23 recommended soaking in povidone-iodine, while Cummings24 has used 0.25% acetic acid. Both substances will clean the wound and promote granulation tissue.

Stell and Cooney21 conceptualized surgical closure of fistulae into three types, and all require closure by two epithelial surfaces.

Type 1 Both tissue surfaces provided locally.

Type 2 One tissue surface provided locally and one provided from a distance.

Type 3 Both surfaces provided from a distance.

All successful closure depends on using healthy, well-vas-cularized tissue. Historically, the deltopectoral flap was used most often for repair of medium and large fistulae3,19 and, although still an option, myocutaneous flaps have become more popular for fistula repair due to the large amount of tissue provided with a reliable blood supply that does not need to be delayed.22,24-26 Free flaps are always an option for repair.27

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