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There are at least five factors to consider when determining risk for periprocedural complications of percutaneous tracheostomy. These circumstances are outlined below.
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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
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Intracranial Hypertension
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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.
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Cervical Spine Injury
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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.
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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
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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
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Severe Respiratory Failure
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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.