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  In critically ill patients, tracheostomy is most commonly performed to facilitate delivery of prolonged mechanical ventilation. Less frequently, it may be performed for relief of upper airway obstruction or for management of chronic pulmonary secretions.

  
  
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  The most compelling reason to perform tracheostomy for patients requiring prolonged mechanical ventilation is to improve patient comfort and decrease sedation requirements.

  
  
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  The available evidence base suggests that performing tracheostomy early in patients expected to require prolonged mechanical ventilation does not reduce mortality, rates of ventilator-associated pneumonia, or duration of intensive care unit admission.

  
  
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  Surgical tracheostomy and percutaneous dilational tracheostomy (PDT) have comparable complication rates, but PDT is often more convenient and requires less resources to perform.

  
  
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  Cricothyroidotomy, rather than tracheostomy, should be the surgical airway of choice in emergency situations, except in the unusual case of subglottic obstruction.

  
  
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  In cases of accidental tracheostomy tube dislodgement occurring before a mature tract has formed, blind attempts at reinserting the tracheostomy tube risk creating a false passage anterior to the trachea. Endotracheal intubation from above is the safest method of airway control in the early posttracheostomy period (eg, <7 days).

Tracheostomy has become one of the most commonly performed procedures in the intensive care unit (ICU), yet there still exists considerable uncertainty regarding its preferred technique, indications, and timing. Between 6% and 20% of patients requiring mechanical ventilation will receive a tracheostomy,^1-3 including a large proportion of patients requiring prolonged mechanical ventilation, accounting for up to one-third of all ventilator days.^4,5 The use of the procedure also appears to have increased over time,⁶ possibly due to the emergence of percutaneous dilational tracheostomy, which has made the procedure more convenient to perform at the bedside.⁷ Determining and refining the appropriate indications for tracheostomy are likely to become increasingly important as more patients survive the acute phase of critical illness and as pressures increase on critical care providers to facilitate patient flow through critical care areas.

Tracheostomy may be considered for a variety of different situations in critically ill patients, but the underlying rationale for the procedure may be simplified to three general indications (Table 46-1). The first is to establish or maintain a patent airway in a patient who has upper airway obstruction or who is incapable of adequate airway protection. The second is to assist with the delivery of positive pressure ventilation in patients with respiratory failure, in an effort to facilitate weaning from mechanical ventilation by reducing dead space and decreasing airway resistance, or to reduce sedative requirements by providing a more comfortable conduit to receive mechanical ventilation. The third is to facilitate clearing of secretions in patients with a need for ongoing pulmonary toilet.

Although the decision to perform a tracheostomy is most straightforward as an emergency treatment of upper airway obstruction, this indication is uncommon. By far the most common reason patients in the ICU will receive a tracheostomy is to assist with the delivery of mechanical ventilation, especially among those expected to require mechanical ventilation for a prolonged time or in anticipation of difficult weaning. However, predicting which patients will require mechanical ventilation of sufficient duration to justify the risks of the procedure is often difficult (see later), and many of the anticipated benefits of performing tracheostomy for these patients have not been confirmed.

For patients who receive tracheostomy because they are expected to require prolonged mechanical ventilation, the risks and benefits of the procedure must be compared to those of prolonged endotracheal intubation. As with most surgical procedures, there are risks of both short- and long-term complications from tracheostomy. In the short term, the most serious risks include loss of the airway, bleeding, and damage to nearby structures such as the esophagus, pleura, and recurrent laryngeal nerves.⁸ Longer-term complications may include infection, skin or cartilage necrosis, tracheo-innominate fistula, tracheomalacia, and tracheal stenosis.⁹ Other complications that are important yet more difficult to quantify include problems with cosmesis and body image as well as potentially a greater need for long-term care and higher caregiver requirements.² The exact incidence of complications does depend to some extent on the technique selected: surgical tracheostomy or percutaneous dilational tracheostomy (Table 46-2).

Many potential benefits have been claimed for performing tracheostomy in patients expected to require prolonged endotracheal intubation. Most notable of these is a belief that the procedure will decrease the duration of mechanical ventilation and, consequently, shorten the duration of ICU stay. Tracheostomy does allow for greater flexibility in weaning patients from the mechanical ventilator. The decreased dead space and, more importantly, the decreased resistance of the shorter tracheostomy tube¹⁰ allow for the patient to be entirely disconnected from the ventilator and breathing unsupported, without the need for extubation and reintubation. Whether these physiological and practical advantages actually translate to a shortened duration of mechanical ventilation or ICU stay remains controversial (see later).

Most critical care practitioners agree that tracheostomy provides a more comfortable conduit for mechanical ventilation than endotracheal intubation.^11-13 This may allow for a reduction in sedation requirements, and thus facilitate weaning from the ventilator and allow for earlier mobilization and a greater degree of patient participation in care, such as physiotherapy. However, the potential of tracheostomy for decreasing sedation requirements has not been consistently observed.^11,13 This may be in part due to the evolving evidence base emphasizing the benefits of daily awakening to minimizing sedative infusions in all patients receiving mechanical ventilation, causing differences in sedation requirements previously noted with tracheostomy to be minimized.¹⁴ Other less quantifiable variables such as improved lip reading and better oral care may further improve the comfort of tracheostomy. Furthermore, in the longer term, patients with tracheostomy do have the potential for swallowing and for speech; though in general this is not possible until positive pressure ventilation is no longer required.

Compared to endotracheal intubation, tracheostomy does provide an airway that is less easily dislodged.¹⁵ This is particularly true once a mature tract has formed which enables relatively easy and safe replacement of a dislodged tracheostomy tube. Once a mature tract has formed, this allows for greater confidence with mobilization and physiotherapy as well as the potential transfer to a level of care without immediate access to personnel with advanced airway skills.

In the past, endotracheal intubation has been implicated as a contributor to airway complications such as tracheal and laryngeal stenosis. The prevention of subglottic stenosis has been cited as a major reason to avoid prolonged endotracheal intubation in ICU patients and to perform tracheostomy after a certain duration of mechanical ventilation.¹⁶ The actual incidence of airway trauma from endotracheal intubation is likely low¹⁷ now that high volume, low pressure cuffs are standard on endotracheal tubes. Tracheostomy tubes have also been associated with tracheal stenosis attributed to cuff insufflation, tracheal trauma and granulomas from the tube tip, and long-term stenosis at the tracheotomy site after decannulation.¹⁷ Patients with prolonged intubations likely do benefit from removing the endotracheal tube to reduce oropharyngeal and laryngeal damage, but whether this offsets the potential tracheal complications of tracheostomy is unclear.¹⁸ We suggest that patients with evidence of oral or pharyngeal ulceration and who are expected to require prolonged mechanical ventilation should be considered for conversion to tracheostomy.

There is some evidence from small trials¹⁹ that tracheostomy may reduce the incidence of ventilator-associated pneumonia (VAP) in ICU patients requiring prolonged mechanical ventilation,²⁰ but these patients were not systematically screened for the development of VAP. The posited mechanisms through which this advantage might be realized include better oral care, more effective suctioning, and improved glottic compliance, resulting in less pooled secretions in the trachea. Recently, a well-designed large trial from Italy evaluated the impact of tracheostomy timing on the incidence of VAP among patients from 12 Italian ICUs with ongoing severe respiratory failure 24 hours after intubation.²¹ Of 600 patients studied, 419 did not significantly improve or worsen according to standardized criteria evaluated 48 hours after enrollment. These patients were randomized to receive percutaneous tracheostomy after 6 to 8 days (early group) or after 13 to 15 days (late group) of laryngeal intubation. Monitoring for VAP was standardized and assessed by blinded adjudicators in an effort to minimize ascertainment bias. There was a statistically nonsignificant trend toward a reduction in VAP with early tracheostomy. However, even if this trend were real (and the trial was underpowered to confirm it), the clinical benefit would appear small; earlier tracheostomy was not associated with reductions in mortality (at 28 days or 1 year) or hospital length of stay.

The optimal timing of tracheostomy for patients that are anticipated to have ongoing ventilator dependence remains controversial. After a prolonged period of mechanical ventilation, the benefits of tracheostomy—in particular increased comfort and ease of connecting and disconnecting from the ventilator—will presumably start to outweigh the risks of the procedure. Numerous studies have attempted to elucidate whether performing tracheostomy earlier in a patient’s ICU stay confers other benefits, particularly considering time to successful liberation from mechanical ventilation and mortality. Unfortunately, study of the subject has been difficult for a number of reasons. Retrospective studies are confounded by indication bias and survivor treatment bias. Randomized trials have also been problematic, mainly because accurate prediction of which patients will require prolonged ventilation has proven to be extremely difficult.²² The enrollment of patients into studies has also been limited by physicians’ fixed perceptions of the benefits of tracheostomy.^13,23

A number of important studies of “early” versus “late” tracheostomy have been published in the last decade. In 2005, a meta-analysis summarized five randomized and quasi-randomized trials published between 1990 and 2004 and involving a total of 406 patients with diverse conditions including trauma, head injury, medical, surgical and burn patients.²⁰ A significant degree of heterogeneity also existed across these studies for definitions of “early” versus “late” tracheostomy. Overall, no difference was observed in mortality or rate of VAP. However, a significant decrease in duration of mechanical ventilation and ICU length of stay was observed for early tracheostomy (defined as <7 days). This meta-analysis was limited by the relatively small number of patients and small number of trials included.

Since publication of this meta-analysis, several large trials have been attempted. A trial conducted in France sought to randomize 468 patients but was terminated because of low enrollment after randomizing 123 patients from 25 ICUs.¹³ Patients that were predicted by their physicians to require prolonged mechanical ventilation (>7 days) were randomized to receive early tracheostomy (within 4 days) versus prolonged translaryngeal intubation (with tracheostomy permitted after 14 days).¹³ The study detected no difference between groups for mortality, VAP rate, duration of mechanical ventilation or amount of sedative medications required, but was likely underpowered to detect clinically important differences.²³ Interestingly, only one quarter (16 of 62) patients that were randomized to receive prolonged intubation subsequently received a tracheostomy after 14 days. The authors did attempt to quantify the comfort of early tracheostomy, noting greater comfort in patients receiving early tracheostomy in the two-thirds of surviving patients that could complete follow-up.

The recent Italian trial of tracheostomy timing has already been discussed.²¹ No significant differences in mortality or VAP were observed comparing the early versus late tracheostomy groups. The duration of mechanical ventilation and, hence, ICU stay were shortened, but there were no changes in hospital length of stay or other long-term outcome measures. Notably, more patients were subjected to the risk of tracheostomy by an early tracheostomy strategy, with little quantifiable benefit.²²

A recent United Kingdom multicenter randomized trial was concluded in 2009 but has not yet been published. This trial (TRACMAN) is the largest conducted to date and enrolled 909 general ICU patients that were predicted to require greater than 7 days of mechanical ventilation.²⁴ Patients were randomized to receive early tracheostomy (within 4 days) or late tracheostomy (after >10 days). The majority (93%) of patients in the early tracheostomy group received a tracheostomy compared with less than half (45%) of the late group. There were no significant differences in 30 day mortality, ICU or hospital length of stay or antimicrobial use (although rates of VAP were not measured). There was decreased use of sedative medications in patients in the early tracheostomy group. This decreased use of sedation, although statistically significant, is of questionable clinical significance considering that ICU length of stay was unaltered in the early tracheostomy group.

A unifying theme of these recent trials of earlier tracheostomy is that accurately predicting which patients will actually require prolonged mechanical ventilation is difficult and susceptible to cognitive biases and uncertainty, even in the most rigorously conducted trials. A strategy of performing early tracheostomy will inevitably involve performing more tracheostomies than are necessary, since many of the patients receiving the procedure would be liberated from mechanical ventilation without the procedure simply by waiting longer. Interestingly, the trials have been inconsistent in detecting differences in sedative requirements comparing early and late tracheostomy strategies, suggesting that sedation use in modern ICUs may be minimized even among endotracheally intubated patients by providing sedation vacations and protocolized care.²⁵ Similarly, other putative benefits of early tracheostomy may be minimized in the future as general ICU care improves, including adoption of standardized weaning protocols and VAP prevention bundles.

The available studies examining the optimal timing of tracheostomy have typically included a broad sampling of ICU patients predicted to require prolonged mechanical ventilation, with a preponderance of primary respiratory failure patients. It still remains to be elucidated whether subpopulations exist, which may derive more benefit from early tracheostomy. A recent trial found no benefit to earlier tracheostomy for cardiac surgery patients that were expected to require prolonged mechanical ventilation.²⁶ Neurosurgical patients may have a prolonged need for airway protection, but require little in the way of ventilator support, and these patients might therefore be liberated from mechanical ventilation immediately after tracheostomy. One trial did demonstrate earlier liberation from mechanical ventilation in head injured patients with early tracheostomy, but detected no differences in rates of VAP or mortality.²⁷ Studying the timing of tracheostomy in these patient subgroups poses other challenges, for example, correctly predicting which patients will be unable to protect their airway after extubation.²⁸ Furthermore, performing early tracheostomy on patients with severe brain injury will be undesirable for patients that are expected to die of their brain injury, and discussions of the risks and benefits of tracheostomy may only serve to complicate discussions of withdrawal of life-sustaining treatment in patients with a predicted poor functional recovery.

GENERAL CONSIDERATIONS

The tracheostomy procedure inevitably leads to an interruption in delivery of positive-end expiratory pressure (PEEP). This loss of PEEP can lead to important derecruitment of lung segments and atelectasis and resultant desaturation and hypoxemia, especially among patients with severe respiratory failure. We therefore recommend deferring or postponing the procedure among patients requiring greater than 10 cm H₂O of PEEP, or among patients that have demonstrated oxygen desaturation with minor changes to their current levels of PEEP or fraction of inspired oxygen.

Serious bleeding during the procedure is uncommon, but any important coagulopathies or thrombocytopenia should be corrected. Loss of airway is also uncommon, but the procedure should only be performed in the presence of individuals with advanced airway skills, and when performing tracheostomy at the bedside, arrangements should be in place to accommodate the need for an operating room and surgical expertise in the event of an airway emergency. Finally, tracheostomy is contraindicated in patients with unstable cervical spine injuries.

SELECTION OF TECHNIQUE

Practitioners generally must select between performing a standard, surgical tracheostomy or a percutaneous dilational tracheostomy. Both techniques may be performed either at the bedside in the ICU or in the operating room, although the most common practice is for percutaneous dilational tracheostomy to be performed in the ICU and surgical tracheostomy to be performed in the operating room.⁷ Percutaneous dilational tracheostomy performed in the ICU is appealing for a number of reasons, in particular decreased costs and increased convenience²⁹

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