Chapter 39: Percutaneous Tracheostomy

This patient is certain to have a prolonged course of mechanical ventilation as a result of neurologic failure, and he should undergo tracheostomy. Although prolonged endotracheal intubation with a modern high-volume low-pressure cuffed tube is safe, infrequently resulting in subglottic stenosis or vocal cord injury,¹ tracheostomy offers several advantages in patients with severe brain injury. These include facilitation of weaning from mechanical ventilation,^{2, 3} prolonged access to the lower airways for secretions management, improved comfort,^{4, 5} and earlier mobilization for physical and occupational therapy. Tracheostomy often makes possible discontinuation of sedating medications,⁵ facilitating the neurologic examination, and may allow brain-injured patients with good cardiopulmonary function to be completely disconnected from mechanical ventilation, preventing the common complications of atelectasis and respiratory muscle atrophy. Disadvantages include perioperative and long-term complications of the procedure and introduction of a potential reservoir of bacterial colonization into the airway. General indications for tracheostomy in the neurocritically ill are presented in Table 39-1.

Optimal timing of tracheostomy in all patient groups is controversial. One randomized single-center trial in the medical intensive care unit (ICU) suggested lower mortality and other benefits when tracheostomy was performed by day 3 as opposed to day 14,⁶ but this finding was not replicated in two subsequent multicenter randomized trials.^{7, 8} A meta-analysis suggested benefits to early tracheostomy in patients expected to receive mechanical ventilation for prolonged periods,⁹ and multiple retrospective studies suggest benefit when tracheostomy is performed before day 7, compared to delayed tracheostomy.^{10, 11, 12, 13, 14, 15} A recent multicenter randomized controlled trial showed a nonsignificant trend toward less ventilator-associated pneumonia in critically ill patients randomized to early tracheostomy vs prolonged mechanical intubation, while the secondary outcome measures of ventilator-free days, ICU-free days, and survival to ICU discharge favored early tracheostomy.¹⁶ Recent trauma guidelines suggest early tracheostomy for patients with severe traumatic brain injury.¹⁷ Considerations in the timing of tracheostomy are summarized in Table 39-2.

Open surgical tracheostomy and, to some degree, modified percutaneous tracheostomy offer direct visualization and palpation of the anatomic structures of the anterior neck, while a pure percutaneous technique relies on careful planning and palpation, familiarity with neck anatomy, and sometimes ultrasound and/or bronchoscopic guidance for optimal results. All three techniques are supported by a vast collective experience, and the experience of the surgeon or proceduralist^{18, 19} is a more important factor in preventing complications than the technique used or subspecialty of the physician.^{20, 21, 22}

Tracheostomy is typically performed between the second and third tracheal rings, well above the innominate artery and below the thyroid isthmus. Major vessels traverse the anterior neck, including the innominate artery, inferior thyroid vein, and carotid artery, and significant anatomic variance in these structures is present within the population. Accidental puncture of large arteries and veins can be averted by routine ultrasonographic imaging prior to the procedure,^{23, 24} especially in obese patients. The surgical field should always be carefully palpated prior to incision and cannulation, but anatomically variant veins will be detected in only the thinnest patients without dissection or ultrasonographic imaging.

Normal neck anatomy is shown in Figures 39-1 and 39-2. The rigid cricoid cartilage is located just inferior to the vocal cords. At the base of this structure, typically superficial and easily palpated, is the cricothyroid membrane—the preferred location for an emergent surgical airway in nonintubated patients owing to its proximity to the skin. Tracheostomy is performed lower, owing to the potential for laryngeal injury with cricothyroidotomy and the tendency for a higher tracheostomy to interfere with laryngeal function. The anterior tracheal wall is cartilaginous and formed by 18 to 22 rings, while the posterior trachea is membranous, thin, and separates the trachea from the esophagus. When tracheomalacia is present, the trachea is collapsible, and anterior and posterior tracheal walls appose under downward pressure, so that bronchoscopic guidance or an open surgical technique should be employed to prevent esophageal injury or paratracheal placement and to facilitate the procedure.²⁵

Clinicians should carefully consider the type and size of tracheostomy tube to be placed. In obese patients, a tube with inadequate depth is at risk of becoming dislodged, resulting in loss of the airway, or may become posteriorly angulated in the neck, resulting in partial airway occlusion against the tracheal wall and increasing the risk of suction trauma and subsequent tracheal stenosis. Conversely, thin patients whose tracheostomy tubes are overlong may suffer erosion of the stoma owing to angulation and pressure causing soft tissue injury, increasing the risk of tracheoinnominate fistula. In all cases, a midline insertion and appropriate angle within the airway are least likely to result in tracheal complications. Different commonly employed tubes have dramatically different inner and outer diameters, angulations, depths, and lengths. Tracheostomy tubes with fenestration (for speech), with variable ventilator interfaces, with and without cuffs, with adjustable lengths, with armor, and with foam or air cuffs are all available from manufacturers, and familiarity with a variety of these products is advised.²⁷

Percutaneous and modified percutaneous tracheostomy techniques are routinely performed by surgeons, and increasingly by anesthesiologists and intensivists of various backgrounds.^{19, 20, 21} The procedure is considered an advanced airway technique, building on expertise in endotracheal intubation, bronchoscopy, and other guidewire-based percutaneous techniques. Multiple percutaneous tracheostomy techniques and commercially produced kits are available, and both the American College of Chest Physicians²⁸ and European Respiratory Society²⁹ have published guidelines for training and certification of competency, typically requiring a minimum number of procedures and a period of supervised apprenticeship. Tracheostomy should be performed by an experienced operator,^{18, 19} with a system in place to provide protocolized tracheostomy care and long-term follow-up. Table 39-3 delineates elements of a successful percutaneous tracheostomy program.

Percutaneous or modified percutaneous tracheostomy performed at the bedside offers convenience and cost savings when compared to surgical techniques, with a similar safety profile.^{21, 30, 31} In the brain-injured population, special attention should be paid to intracranial pressure, cervical spine injury, and strict preservation of metabolic and hemodynamic homeostasis during the procedure. These issues are described in greater detail below.

Procedural Technique

The neck is examined and anatomic features noted. Is the trachea easily palpated? Note the thyroid and cricoid cartilage and the cricothyroid ligament. Are the cartilaginous rings easily palpated and rigid? Is the innominate artery palpable in or above the sternal notch, or are there thyroid anomalies that warrant further evaluation? Can the neck be moderately extended to bring the trachea closer to the skin surface? If obesity, deformity or anatomic irregularity, prior tracheostomy, or other concerns exist, then ultrasonographic or CT evaluation may be necessary prior to the procedure.^{23, 24} Surgical marking pens are often used to define procedural anatomy prior to incising the skin.

The neck is prepared in sterile fashion, and the skin and subdermal tissues overlying the second/third cartilaginous interspace is infused with a lidocaine-epinephrine mixture. After analgesia and sedation, a transverse incision is performed. In the pure percutaneous technique, the trachea is then cannulated without blunt dissection and a guidewire is inserted. In the modified technique, blunt dissection down to the trachea is performed and the trachea is cannulated under direct visualization prior to guidewire insertion. Not all proceduralists use bronchoscopic guidance to visualize the tracheal puncture,^{21, 32, 33} but such visualization adds a measure of safety, especially when a pure percutaneous technique is used, in that tracheal placement is confirmed at the time of puncture, midline insertion is confirmed, and injury to the posterior tracheal wall or esophagus is avoided with certainty.

Confirmation of tracheostomy placement is critical, since most of the rare fatalities associated with the procedure occur either because of paratracheal placement or when the tube is dislodged from the airway and cannot be rapidly replaced. Tracheal insertion may be verified by direct visualization, capnography, ventilator pressure-volume waveforms, breath sounds and chest rise, or gas exchange—typically, multimodal verification is suggested. The tube is then sutured into place.

Percutaneous tracheostomy has a mortality rate below 1%.^{34, 35, 36} Reported complications vary widely: a 2006 report described 1000 sequential percutaneous tracheostomy procedures using a single technique, including more than 50% in patients regarded as “high risk” owing to either hypoxemia, cervical spine injury, or coagulopathy, with an overall 1.5% incidence of significant periprocedural complications.³⁴ At the other extreme, a 2005 series reported 22.2% overall complications (though 90% of these were considered minor) in 474 patients using a mixed series of procedural techniques.³⁷ This wide variability in complications, which persists in review of other published case series, suggests that procedural safety may depend on the systematic application of a single safe technique (Table 39-4).

The most serious early complication of percutaneous tracheostomy is paratracheal insertion—potentially fatal if unrecognized, but easily avoided by systematic and multimodal assessment of tube position; by using longer tracheotomy tubes in obese patients, which seat securely in the trachea; by securing tubes appropriately; and by cautious perioperative manipulation and assessment. Great care should be taken to avoid early displacement of the tracheostomy tube, and protocols should be in place to manage tube malposition. If malposition occurs and the airway is lost, oral reintubation should be immediately performed to reestablish a definitive airway.

Pneumothorax and pneumomediastinum are uncommon. In older series, damage to the posterior tracheal wall was noted in up to 12% of procedures,^{36, 38} but this complication can be easily avoided by employing bronchoscopic guidance. Minor bleeding from the stoma is common, but because of the tamponading effect of the tracheostomy tube, it is self-limited, and when it continues, it can often be controlled by packing gauze circumferentially around the tube and then tightly into the stoma on the outside of the tube. Removal of the tracheostomy tube to evaluate bleeding should almost always be avoided unless arterial repair is clearly necessary or the airway has been lost. With the dilational technique, bleeding into the airway after completion of the procedure is unusual, though minor bleeding into the airway during the procedure is not uncommon. More significant hemorrhage can occur if blood vessels are damaged during insertion. This bleeding rarely requires surgical or endovascular repair. Patients undergoing open surgical tracheostomy are more likely to experience significant bleeding and wound infections.^{36, 39}

Life-threatening bleeding may occur in the setting of tracheoinnominate fistula (TIF). TIF is historically reported to occur in 0.3% of tracheostomies—typically within a month of the procedure.^{36, 38} In most patients, the innominate artery crosses the trachea anteriorly at approximately the ninth tracheal ring,²⁵ but anatomic variation is not uncommon, and the artery may ride in or above the sternal notch. Low-placed tracheostomy tubes or pressure necrosis, more commonly occurring at the tip of the tube than at the insertion site, can lead to erosion into the innominate artery. TIF can result from erosion, excessive traction on the tube, chronic overinflation of the tracheostomy cuff, excessive angulation of the tube, or stomal infection. If TIF occurs, the first responder should attempt superinflation of the cuff and anterior traction on the tube, to compress the innominate artery against the posterior sternum. It is also possible to insert a finger into the stoma and provide anterior compression of the innominate artery against the back of the sternum, though the airway must be maintained. Urgent sternotomy and surgical ligation of the artery or endovascular repair is then required to control bleeding.^{40, 41}

Tracheal stenosis may develop at the level of tracheostomy insertion, at the cuff, or at the tip of the tube.^{36, 38} The condition is usually a result of pressure necrosis of the tracheal wall from a tight-fitting tube, high-pressure cuff, off-midline insertion, or mechanical irritation due to frequent levering of the tube by poorly supported ventilator tubing or head movements. Pressure necrosis of the trachea leads to formation of a fibrous scar and transmural airway narrowing. Symptoms usually manifest 2 to 6 weeks after decannulation, but have been reported up to 6 months after tracheostomy removal. Patients may present with difficulty clearing secretions, exertional dyspnea, persistent cough, or stridor. Flattening of the inspiratory limb on the flow-volume loop suggests at least 80% narrowing of the tracheal lumen. Tracheal stenosis may be suggested by CT images, but should be confirmed by bronchoscopic visualization. Treatment involves laser excision, surgery, or tracheal stent placement.³⁸

There are at least five factors to consider when determining risk for periprocedural complications of percutaneous tracheostomy. These circumstances are outlined below.

Coagulopathy

Although small series have suggested the safety of percutaneous tracheostomy in the settings of coagulopathy and thrombocytopenia, standard practice is the complete reversal of coagulopathy to an international normalized ratio (INR) of less than 1.5, a normal partial thromboplastin time (PTT), and platelets greater than 100,000 whenever possible. Under high-risk circumstances, it is occasionally necessary to consider tracheostomy in coagulopathic patients, such as those with mechanical heart valves, recent deep vein thrombosis/pulmonary embolism, or advanced liver disease. Although these procedures are often well tolerated, the actual risk of serious bleeding is unknown, and the decision to proceed with tracheostomy is based on careful accounting of the anticipated benefits of the procedure.^{42, 43, 44, 45}

Intracranial Hypertension

Several case series suggest that the percutaneous tracheostomy procedure causes a significant increase in ICP.^{46, 47} These increases may be due to pain, fear, or hypoventilation—all of which must be studiously avoided by proceduralists. Hypoventilation during tracheostomy of a patient with elevated ICP or poor intracranial compliance at baseline may result in catastrophic intracranial hypertension, so end-tidal Co₂ and ICP monitoring are therefore indicated when ICP is known or suspected to be elevated, when intracranial compliance is poor, or when brain imaging suggests mass effect. Under these circumstances, it is advisable to delay tracheostomy. If tracheostomy is performed, bronchoscopy time must be minimized,⁴⁸ patients may require modest hyperventilation prior to the procedure, the airway must never be compromised, and care must be taken to ensure that sedation and analgesia do not lead to hypotension. Deep sedation and excellent pain control are essential, so it is advisable to have vasopressors on hand at the onset of the procedure.

Cervical Spine Injury

Although case series suggest procedural success,^{35, 49, 50} the safety of percutaneous tracheostomy in patients with an unstable or a suspected unstable cervical spine remains unknown, and the procedure should be undertaken with caution and trepidation. In-line cervical stabilization and posterior support are critical, and even modest downward pressure from the dilations must be absolutely avoided. Under these conditions, the modified percutaneous or open surgical techniques are preferred in order to minimize downward force. A newer percutaneous device (Ciaglia Blue Dolphin, Cook Medical, Bloomington, IN), based on balloon dilatation, may offer the advantage of substituting a radial vector of force for the usual tangential vectors, but safety data are not yet available in this population or with the device under these circumstances. Bronchoscopy is a crucial airway management measure in this population since neck manipulation must be minimized, and in the event of accidental loss of the airway, the bronchoscope facilitates safe reintubation.

Obesity

Percutaneous tracheostomy is frequently performed in obese and morbidly obese patients, but it is likely that their periprocedural complications are higher. One study evaluated 474 patients who underwent percutaneous tracheostomy, of whom 73 were obese (defined as body mass index [BMI] > 27.5), and found a higher complications rate among obese than nonobese patients (43.8% vs 18.2%; P < .001).³⁵ This finding was echoed in a series of 500 single-center tracheostomies performed in Canada, where patients with a BMI greater than or equal to 30 had a higher rate of complications (15% vs 8%; P < .05).⁵¹ Conversely, one institution reported on 143 percutaneous tracheostomy experiences in morbidly obese patients (defined as having a BMI > 35), finding only 1.1% to have overall complications, including bleeding, and 5.6% to have conversion to an open procedure.⁵²

When planning tracheostomy in obese patients, it is reasonable to consider preprocedure ultrasound evaluation of the neck to visualize vascular structures, thyroid tissue, and anatomic variants. Proceduralists should rigorously consider the shape and length of the tracheostomy tube, which can become anteriorly displaced or downward angulated if insufficiently long or deep.²⁷

Severe Respiratory Failure

Although patients with high levels of Fio₂ and PEEP are sometimes considered “high risk,” two publications suggest these patients can safely undergo percutaneous tracheostomy. The first evaluated 88 patients ventilated with high PEEP (> 7.5 mm Hg), finding no short- (1-hour) or long-term (24-hour) disturbances in oxygenation and no absolute or statistical difference in procedural complications when they were compared with 115 similar patients undergoing tracheostomy with low PEEP.⁵³ The second large series demonstrated an extremely low rate of procedural complications among 1000 patients, despite the inclusion of 150 patients with an Fio₂ greater than 0.5 and 110 patients with a PEEP greater than 10 mm Hg.³⁷ These authors suggest that tracheostomy be delayed when the Fio₂ is greater than 80% or the PEEP is greater than 15 cm H₂O.

Tracheostomy offers many advantages to prolonged endotracheal intubation in the critically ill neuroscience patient, but its benefit depends on safety. Tracheostomy safety is improved by standardized care under institutional protocols and pathways and the standardized involvement of nurses and respiratory care practitioners. A tracheostomy program serves to decrease low-frequency, high-risk events and depends on appropriate patient selection, standardized procedural techniques by experienced practitioners, appropriate tube selection and management, and protocolized long-term management.^{35, 54, 55, 56} In the modern era of quality initiatives and the safety culture, such a program is considered a standard element of patient care.