Tracheostomy

Tracheostomy is an operation in which an opening is made in the trachea (windpipe) and a tube is inserted in order to maintain an effective airway. A tracheostomy is used for the emergency treatment of various airway problems involving the larynx (voicebox). A planned tracheostomy is most commonly performed on a person who has lost the ability to breathe naturally and is undergoing long-term ventilation or is unable to keep saliva and other secretions out of the trachea. Permanent tracheostomy is needed after laryngectomy (removal of the larynx).

Tracheostomy in detail - technical

Summary

Tracheostomy is one of the most common and oldest surgical procedures performed. It provides direct access to the airway for ventilatory support, repeated bronchoscopic evaluation, management of secretions, and provides an airway in the setting of upper airway obstruction. The indications, technique, and complications associated with standard surgical and percutaneous approaches to tracheostomy are highlighted within this article, with special focus on diagnosis and management of the potentially lethal complication of a tracheoinominate fistula.

Introduction

Tracheostomy has been utilized as a means to obtain access to the airway since ancient times. It is one of the oldest surgical procedures on record, with descriptions found in the sacred Hindu text Rig Veda dating back to 1500 BC. Tracheostomy has largely been utilized as an emergency procedure for treating acute upper airway obstruction, particularly during the diphtheria epidemics of the eighteenth and nineteenth centuries. More recently, tracheostomy is increasingly performed as an elective procedure airway in ventilator-dependent patients with acute or chronic respiratory failure, or in patients with sleep apnea or underlying pulmonary diseases that require either continuous or intermittent respiratory support. In general, a tracheostomy provides direct access to the airway for ventilatory support, repeated bronchoscopic evaluation, management of secretions, and provides an airway in the setting of upper airway obstruction. The first modern description of tracheostomy was in 1909 by Chevalier Jackson and this approach remains the gold standard. More recent modifications to allow percutaneous tracheostomy placement have evolved, and in the correct patient population can offer an appropriate alternative surgical approach. Despite the noninvasive appearance of these percutaneous approaches, these methods are not to be used in emergency situations; rather a cricothyroidectomy should still be employed, due to the ease and rapidity with which airway access can be obtained in skilled hands using this approach. The remainder of this article will focus on the indications, available techniques, and the identification and treatment of complications associated with tracheostomy.

The Scientific Basis

Anatomy

The adult trachea is approximately 10–11 cm in length, extending from the level of the sixth cervical vertebra to the fourth thoracic vertebra. Only approximately 5 cm of the trachea is located above the suprasternal notch. The trachea is elliptical in shape with the transverse diameter being greater than the anterioposterior diameter, secondary to 16–20 horseshoe-shaped cartilaginous rings that are located anteriorly. The posterior tracheal wall is known as the membraneous trachea and consists of a fibrinous sheath with elements of smooth muscle, epithelium, and glandular tissue. The cricoid cartilage is the only complete ring in the airway and sits at the beginning of the trachea, with the cricothyroid membrane spanning the distance between the thyroid cartilage and the cricoid. Although the cricoid cartilage is often described as the first ring, it is technically a part of the larynx and is not considered a true tracheal ring. The superior surface of the cervical trachea is covered by the thyroid isthmus. Although usually above the site of tracheostomy placement, occasionally this gland must be divided to achieve adequate access to the trachea. The blood supply to the cervical trachea arises from the inferior thyroid vessels and associated branches. The lower trachea is supplied by branches from the bronchial arteries. The vessels approach the trachea laterally on each side forming a vascular network.

Ideally, the tracheotomy is made between the second and third tracheal rings. It is important during the placement of a tracheostomy to note that the trachea is a mobile structure and moves with inspiration, such that the distal trachea may descend several centimeters into the thorax. Similarly, hyperextension of the neck can result in the intrathoracic portion of the trachea rising above the suprasternal notch, resulting in the placement of a tracheostomy that resides too low in the trachea when the head is returned to a neutral position.

Indications

Tracheostomy is still indicated for the relief of airway obstruction, as occurs with sleep apnea, glottic stenosis, tumor, trauma, chronic laryngeal edema, or bilateral vocal cord paralysis. However, the most common indication for tracheostomy is to facilitate pulmonary toilet and ventilatory support for chronically ventilated patients. Tracheostomy has several advantages over prolonged translaryngeal intubation. They include: (1) decreased risk of vocal cord injury and subglottic stenosis, (2) improved patient comfort, (3) increased patient mobility, (4) decreased rates of sinusitis, (5) improved oral hygiene, (6) improved access to the airway for clearance of secretions and for bronchoscopy, and (7) the potential for speech with the aid of fenestrated devices.

There continues to be much debate about the ideal timing of tracheostomy following intubation. In general, tracheostomy is a reasonable option for critically ill patients in whom extubation is likely to be delayed. In the not so distant past, when there were numerous complications associated with the use of rigid, low-volume, high-pressure endotracheal cuffs, this had been deemed to be as short as 3 or 4 days. With the widespread use of low-pressure endotracheal cuffs, current complication rates secondary to strictures and ischemia have significantly decreased and translaryngeal intubation can be used for extended periods of up to 3 weeks without issue, particularly if the patient is considered at high risk for the placement of an operative tracheostomy.

Although a relatively safe procedure, most patients are fairly ill at the time of tracheostomy accounting for a 4–10% morbidity but a o1% mortality. A variety of complications have been associated with tracheostomy placement including more limited problems such as localized infection, mucosal or incisional bleeding, granuloma formation at the stoma site, and swallowing dysfunction. However, more serious and long-term complications – such as tracheal ring rupture, tracheoinonimate fistula, tracheoesophageal fistula, tracheal stenosis, or tracheomalacia – some of which are life-threatening, can also occur. Therefore, the timing of tracheostomy must weigh the risk of complications from a tracheostomy with numerous factors including the probability of extubation, potential complications of multiple episodes of respiratory failure, and urgent reintubations, as well as the patient’s and family’s wishes. Timing should be individualized and thus no strict timelines should be mandated; however, prolonged intubation for 7–10 days without likely extubation over the ensuing week should prompt consideration of whether a tracheostomy would be of benefit in the care or ventilatory weaning of the patient.

Contraindications for a tracheostomy include patients with high ventilatory requirements and poor oxygenation whereby the patient requires high levels of positive end expiratory pressure or oxygenation. This prohibits the patient from safely tolerating brief periods of apnea which are required for the exchange of the endotracheal tube for a tracheostomy tube. Other relative contraindications include bleeding disorders, hemodynamic instability, or anatomic restrictions such as an obese body habitus, elevated innominate artery, or short neck.

Tracheostomy Appliances

The choice of the correct type of appliance requires knowledge of the appliance and features of the appliance appropriate for a particular patient. Important design information includes the inner and outer diameter, length, and presence or absence of a balloon cuff, inner cannula, or fenestrations. A tracheostomy should be large enough to provide adequate access for the desired purpose (i.e., ventilation and bronchoscopic pulmonary toilet) without leading to stenosis associated with oversized cannulas. Small diameter cannulas result in increased airway resistance; therefore, smaller cannulas are often reserved for patients who do not require ventilation, and thus most often are placed without a balloon cuff. Appliance length is typically fixed but adjustable devices are available. The ideal length places the cannula 3–4 cm proximal to the carina. A fenestrated tracheostomy permits speech when the tracheostomy is capped and the fenestrations are open. Ventilation can be accomplished with a fenestrated tracheostomy, but the balloon must be inflated and an inner cannula without fenestrations is required to prevent loss of tidal volume through the oral cavity. However, fenestrations are often associated with increased granulation tissue within the airway and difficulties with suctioning; therefore, if the patient is to remain intubated and the fenestrations are not initially required, a nonfenestrated tracheostomy is the preferred initial choice with a plan for changing to a fenestrated tracheostomy when warranted. Alternatively, a one-way Pasey–Muir valve can be placed in order to permit speech with a nonfenestrated tracheostomy; however, failure to deflate the balloon cuff will result in the inability to exhale and the patient can succumb to respiratory failure if this is not identified. Given the number of variables available, careful thought can result in a tracheostomy tailored for specific indications and optimized for each individual patient.

Techniques

Tracheostomy

Surgical tracheostomy is usually performed under general anesthesia in the operating room. With the patient in a supine position, the neck is mildly extended and a 2–3 cm transverse skin incision is made in the midline just above the suprasternal notch. The subcutaneous tissues and platysma are divided transversely; the superficial cervical fascia is divided transversely. Separation of the strap muscles at the median raphe reveals the thyroid isthmus and the underlying trachea. After choosing the appropriate appliance and sufficiently identifying the second and third tracheal rings, a small incision between these rings is made. Most surgeons will either divide the third ring or make a ‘Bjork flap’ to assure adequate access to the airway. Hemostasis must be obtained, but the risk of an airway fire mandates that electrocautery and FiO2 be minimized as much as possible during this portion of the operation. When all OR personnel are ready, ventilation is held and the endotracheal tube is slowly removed by the anesthesia team while the surgical team observes the trachea through the tracheotomy. Once sufficient airway is visible, the tracheal opening can be enlarged gently with a tracheal dilator and the tracheostomy tube placed under direct vision. The cuff is inflated, respirations are resumed, and correct position within the airway is documented by CO2 return, bilateral chest elevation, and ideally bronchoscopy through the tracheostomy applicance. The tracheostomy is securely sutured to the skin and/or secured with a tie around the posterior neck to prevent loss of the airway in the immediate postoperative period. The endotracheal tube should not be removed from the upper trachea until correct positioning of the tracheostomy has been confirmed, as this allows the endotracheal tube to be advanced and the patient again ventilated if there is difficulty with insertion of the tracheostomy tube.

Percutaneous tracheostomy techniques have recently increased in popularity due to the ability to perform the procedure at the bedside with reported economic savings secondary to exclusion of operating room costs. Recent studies comparing standard surgical techniques with dilational percutaneous tracheostomy suggest lower rates of peristomal bleeding and infection at a potential cost benefit. These procedures are best performed with direct bronchoscopic observation of serial dilations over a wire placed percutaneously into the trachea, after the endotracheal tube has been withdrawn above the first tracheal ring. The percutaneous tract, placed using the same landmarks as for a surgical tracheostomy, is serial dilated until a tracheostomy tube can be accommodated and this is slid over the guidewire and into position within the trachea. Some studies have reported increased complications with percutaneous techniques – such as inadvertent injury to the thyroid or other structures within the neck, puncture of the indwelling endotracheal tube, injury to the membranous trachea, or dilation of a false tract with placement of the tracheostomy tube outside of the trachea. Therefore, relative contraindications for this approach would include need for an urgent airway, obesity that prevents landmark identification, known abnormal anatomy such as a ‘high’ innominate artery, enlarged thyroid, or prior neck or tracheal surgery. Direct bronchoscopic guidance has decreased the incidence of many of these complications. It is likely that with proper patient selection and technique, percutaneous approaches are equivalent to standard surgical techniques.

Cricothyroidotomy

Utilized predominantly in the emergency setting for rapid, safe airway access when translaryngeal intubation has been unsuccessful or is not possible due to anatomy or trauma, cricothyroidotomy is performed through either a vertical or horizontal incision depending on patient anatomy, the familiarity of the practitioner with surgical anatomy of the neck, and prior experience with tracheostomy. In contrast to a tracheotomy, a cricothyroidotomy is made above the cricoid cartilage with passage through the cricothyroid membrane. The incision is gently dilated and a small endotracheal tube or tracheostomy tube can be placed through the cricothyroid membrane, taking care not to fracture the cricoid ring or place the tracheostomy in a false passage. Confirmation of accurate placement is made in exactly the same manner as discussed previously for tracheostomy. Cricothyroidotomy has been associated with an increased incidence of subglottic stenosis and thus, if continued ventilatory support is required, most surgeons advocate conversion to a standard tracheostomy in 2–3 days when the patient is stable.

Complications

Both percutaneous and standard tracheostomy techniques are associated with complications. Bleeding can occur from multiple sources. Minor bleeding can occur from small vessels at the site of the incision or from the tracheal mucosa. This bleeding is usually self-limited and can be controlled with minimal manual pressure. Bleeding which occurs 2–3 weeks following tracheostomy placement should suggest a possible tracheoinominate fistula (TIF), and appropriate diagnostic studies and surgical intervention are mandatory. Although TIF is rare, occurring in less than 1% of patients, it is lethal if not promptly treated. The first indication of a TIF is a minor ‘sentinel’ bleed. If the TIF is not recognized and treated immediately, massive hemorrhage and hemoptysis follows as the innominate artery bleeds into the trachea or out of the tracheotomy. Bronchoscopy is the best method to diagnose a suspected TIF, and if the suspicion is high, this should be performed in the operating room with a skilled anesthesiologist and cardiopulmonary bypass available. Other diagnostic tests such as computed tomography of the neck with intravenous contrast or magnetic resonance imaging can be useful, but may waste precious time that is better used in the operating room to repair the fistula. In the case of an actively bleeding TIF, the tracheal cuff should be quickly hyperinflated as an immediate temporizing maneuver, in an attempt to tamponade the fistula with the tracheal balloon. If this is unsuccessful, orotracheal intubation should be rapidly performed, followed by removal of the tracheal cannula with the insertion of a finger into the stoma to manually apply pressure against the innominate artery to compress it against the sternum. This will result in compression of the inominate artery and tamponade the bleeding fistula on the way to the operating room where operative repair of the TIF can be performed.

A tracheoesophageal fistula can also develop and typically presents with aspirated tube feeds in the setting of gastric dilation, or decreased tidal volumes when nasogastric suctioning is performed. Like TIF, tracheoesophageal fistula are also best diagnosed by bronchoscopy; however, these can sometimes be temporized by esophageal or airway stenting prior to definitive surgical repair. Other relatively minor complications of tracheostomy include local infection at the stoma site that usually resolves with antibiotic therapy, and tracheal stenosis which may resolve with dilation following decannulation or eventually require tracheal resection of the involved segment.

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