Official reprint from UpToDate®
www.uptodate.com ©2017 UpToDate, Inc. and/or its affiliates. All Rights Reserved.

Overview of tracheostomy

Robert C Hyzy, MD
Section Editor
Praveen N Mathur, MB;BS
Deputy Editor
Geraldine Finlay, MD


Airway access for mechanical ventilation can be provided either by endotracheal or tracheostomy tube. During episodes of acute respiratory failure, patients are generally ventilated through an endotracheal tube. Changing to a tracheostomy tube is often considered when the need for mechanical ventilation is expected to be prolonged. An overview of clinical issues related to tracheostomy will be discussed here. General issues regarding endotracheal intubation and prolonged ventilation are presented separately. (See "Complications of the endotracheal tube following initial placement: Prevention and management in adult intensive care unit patients" and "Management of the difficult-to-wean adult patient in the intensive care unit" and "Management and prognosis of patients requiring prolonged mechanical ventilation".)


The relative advantages and disadvantages of tracheostomy and endotracheal intubation are outlined in the table (table 1).

Work of breathing — Data from small studies suggest that work of breathing, pressure-time product, airway resistance, peak inspiratory pressures, and intrinsic positive end-expiratory pressure (ie, auto-PEEP) decrease after tracheostomy in both ventilated and spontaneously breathing patients [1-4]. As a result, standard weaning parameters such as the rapid shallow breathing index improve in difficult to wean patients following the conversion from endotracheal tube to tracheostomy [5]. In addition, ventilator synchrony and triggering may be enhanced, although tidal volume, respiratory rate, and dead space ventilation remain unchanged [1,6]. These changes – along with other variables such as secretion, clearance, and patient comfort – may facilitate weaning from mechanical ventilation.

Aspiration — Aspiration of oropharyngeal contents is common with both tracheostomy and endotracheal intubation. It is a result of both pharyngeal pooling of secretions above the airway cuff and delayed triggering of the swallow response [7,8]. The risk of aspiration is directly related to the amount of oropharyngeal secretions.

Videofluoroscopic studies have failed to demonstrate an alteration in swallowing mechanics just prior to decannulation [9]. However, in patients who have a tracheostomy, aspiration occurs in 30 to 50 percent and is clinically silent in 75 to 82 percent of cases [10-12]. Occlusion of the tracheostomy with a cap or finger for phonation does not significantly increase the frequency of aspiration [12]. The likelihood of aspiration may decrease somewhat after a tracheostomy has been present for three weeks [11].

To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information on subscription options, click below on the option that best describes you:

Subscribers log in here

Literature review current through: Nov 2017. | This topic last updated: Oct 13, 2016.
The content on the UpToDate website is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your own physician or other qualified health care professional regarding any medical questions or conditions. The use of this website is governed by the UpToDate Terms of Use ©2017 UpToDate, Inc.
  1. Diehl JL, El Atrous S, Touchard D, et al. Changes in the work of breathing induced by tracheotomy in ventilator-dependent patients. Am J Respir Crit Care Med 1999; 159:383.
  2. Davis K Jr, Campbell RS, Johannigman JA, et al. Changes in respiratory mechanics after tracheostomy. Arch Surg 1999; 134:59.
  3. Moscovici da Cruz V, Demarzo SE, Sobrinho JB, et al. Effects of tracheotomy on respiratory mechanics in spontaneously breathing patients. Eur Respir J 2002; 20:112.
  4. Lin MC, Huang CC, Yang CT, et al. Pulmonary mechanics in patients with prolonged mechanical ventilation requiring tracheostomy. Anaesth Intensive Care 1999; 27:581.
  5. Lim CK, Ruan SY, Lin FC, et al. Effect of Tracheostomy on Weaning Parameters in Difficult-to-Wean Mechanically Ventilated Patients: A Prospective Observational Study. PLoS One 2015; 10:e0138294.
  6. Mohr AM, Rutherford EJ, Cairns BA, Boysen PG. The role of dead space ventilation in predicting outcome of successful weaning from mechanical ventilation. J Trauma 2001; 51:843.
  7. DeVita MA, Spierer-Rundback L. Swallowing disorders in patients with prolonged orotracheal intubation or tracheostomy tubes. Crit Care Med 1990; 18:1328.
  8. Amathieu R, Sauvat S, Reynaud P, et al. Influence of the cuff pressure on the swallowing reflex in tracheostomized intensive care unit patients. Br J Anaesth 2012; 109:578.
  9. Kang JY, Choi KH, Yun GJ, et al. Does removal of tracheostomy affect dysphagia? A kinematic analysis. Dysphagia 2012; 27:498.
  10. Elpern EH, Scott MG, Petro L, Ries MH. Pulmonary aspiration in mechanically ventilated patients with tracheostomies. Chest 1994; 105:563.
  11. Leder SB. Incidence and type of aspiration in acute care patients requiring mechanical ventilation via a new tracheotomy. Chest 2002; 122:1721.
  12. Donzelli J, Brady S, Wesling M, Theisen M. Secretions, occlusion status, and swallowing in patients with a tracheotomy tube: a descriptive study. Ear Nose Throat J 2006; 85:831.
  13. Lucangelo U, Zin WA, Antonaglia V, et al. Effect of positive expiratory pressure and type of tracheal cuff on the incidence of aspiration in mechanically ventilated patients in an intensive care unit. Crit Care Med 2008; 36:409.
  14. Belafsky PC, Blumenfeld L, LePage A, Nahrstedt K. The accuracy of the modified Evan's blue dye test in predicting aspiration. Laryngoscope 2003; 113:1969.
  15. Donzelli J, Brady S, Wesling M, Craney M. Simultaneous modified Evans blue dye procedure and video nasal endoscopic evaluation of the swallow. Laryngoscope 2001; 111:1746.
  16. Potts RG, Zaroukian MH, Guerrero PA, Baker CD. Comparison of blue dye visualization and glucose oxidase test strip methods for detecting pulmonary aspiration of enteral feedings in intubated adults. Chest 1993; 103:117.
  17. Leder SB. Importance of verbal communication for the ventilator-dependent patient. Chest 1990; 98:792.
  18. Manzano JL, Lubillo S, Henríquez D, et al. Verbal communication of ventilator-dependent patients. Crit Care Med 1993; 21:512.
  19. Prigent H, Samuel C, Louis B, et al. Comparative effects of two ventilatory modes on speech in tracheostomized patients with neuromuscular disease. Am J Respir Crit Care Med 2003; 167:114.
  20. Hoit JD, Banzett RB, Lohmeier HL, et al. Clinical ventilator adjustments that improve speech. Chest 2003; 124:1512.
  21. Nomori H. Tracheostomy tube enabling speech during mechanical ventilation. Chest 2004; 125:1046.
  22. Georges H, Leroy O, Guery B, et al. Predisposing factors for nosocomial pneumonia in patients receiving mechanical ventilation and requiring tracheotomy. Chest 2000; 118:767.
  23. Ibrahim EH, Tracy L, Hill C, et al. The occurrence of ventilator-associated pneumonia in a community hospital: risk factors and clinical outcomes. Chest 2001; 120:555.
  24. Nseir S, Di Pompeo C, Jozefowicz E, et al. Relationship between tracheotomy and ventilator-associated pneumonia: a case control study. Eur Respir J 2007; 30:314.
  25. Möller MG, Slaikeu JD, Bonelli P, et al. Early tracheostomy versus late tracheostomy in the surgical intensive care unit. Am J Surg 2005; 189:293.
  26. Ahmed N, Kuo YH. Early versus late tracheostomy in patients with severe traumatic head injury. Surg Infect (Larchmt) 2007; 8:343.
  27. Arabi Y, Haddad S, Shirawi N, Al Shimemeri A. Early tracheostomy in intensive care trauma patients improves resource utilization: a cohort study and literature review. Crit Care 2004; 8:R347.
  28. Griffiths J, Barber VS, Morgan L, Young JD. Systematic review and meta-analysis of studies of the timing of tracheostomy in adult patients undergoing artificial ventilation. BMJ 2005; 330:1243.
  29. Rumbak MJ, Newton M, Truncale T, et al. A prospective, randomized, study comparing early percutaneous dilational tracheotomy to prolonged translaryngeal intubation (delayed tracheotomy) in critically ill medical patients. Crit Care Med 2004; 32:1689.
  30. Mehta AB, Cooke CR, Wiener RS, Walkey AJ. Hospital Variation in Early Tracheostomy in the United States: A Population-Based Study. Crit Care Med 2016; 44:1506.
  31. Stone DJ, Bogdonoff DL. Airway considerations in the management of patients requiring long-term endotracheal intubation. Anesth Analg 1992; 74:276.
  32. Heffner JE. Timing of tracheotomy in mechanically ventilated patients. Am Rev Respir Dis 1993; 147:768.
  33. Plummer AL, Gracey DR. Consensus conference on artificial airways in patients receiving mechanical ventilation. Chest 1989; 96:178.
  34. Bishop MJ. The timing of tracheotomy. An evolving consensus. Chest 1989; 96:712.
  35. Esteban A, Anzueto A, Alía I, et al. How is mechanical ventilation employed in the intensive care unit? An international utilization review. Am J Respir Crit Care Med 2000; 161:1450.
  36. Scales DC, Thiruchelvam D, Kiss A, Redelmeier DA. The effect of tracheostomy timing during critical illness on long-term survival. Crit Care Med 2008; 36:2547.
  37. Colice GL, Stukel TA, Dain B. Laryngeal complications of prolonged intubation. Chest 1989; 96:877.
  38. Colice GL. Resolution of laryngeal injury following translaryngeal intubation. Am Rev Respir Dis 1992; 145:361.
  39. Blot F, Similowski T, Trouillet JL, et al. Early tracheotomy versus prolonged endotracheal intubation in unselected severely ill ICU patients. Intensive Care Med 2008; 34:1779.
  40. Teoh WH, Goh KY, Chan C. The role of early tracheostomy in critically ill neurosurgical patients. Ann Acad Med Singapore 2001; 30:234.
  41. Trouillet JL, Luyt CE, Guiguet M, et al. Early percutaneous tracheotomy versus prolonged intubation of mechanically ventilated patients after cardiac surgery: a randomized trial. Ann Intern Med 2011; 154:373.
  42. Terragni PP, Antonelli M, Fumagalli R, et al. Early vs late tracheotomy for prevention of pneumonia in mechanically ventilated adult ICU patients: a randomized controlled trial. JAMA 2010; 303:1483.
  43. Wang F, Wu Y, Bo L, et al. The timing of tracheotomy in critically ill patients undergoing mechanical ventilation: a systematic review and meta-analysis of randomized controlled trials. Chest 2011; 140:1456.
  44. Gomes Silva BN, Andriolo RB, Saconato H, et al. Early versus late tracheostomy for critically ill patients. Cochrane Database Syst Rev 2012; :CD007271.
  45. Young D, Harrison DA, Cuthbertson BH, et al. Effect of early vs late tracheostomy placement on survival in patients receiving mechanical ventilation: the TracMan randomized trial. JAMA 2013; 309:2121.
  46. Hosokawa K, Nishimura M, Egi M, Vincent JL. Timing of tracheotomy in ICU patients: a systematic review of randomized controlled trials. Crit Care 2015; 19:424.
  47. Nelson JE, Cox CE, Hope AA, Carson SS. Chronic critical illness. Am J Respir Crit Care Med 2010; 182:446.
  48. Nelson JE, Mercado AF, Camhi SL, et al. Communication about chronic critical illness. Arch Intern Med 2007; 167:2509.
  49. Futran ND, Dutcher PO, Roberts JK. The safety and efficacy of bedside tracheotomy. Otolaryngol Head Neck Surg 1993; 109:707.
  50. Marx WH, Ciaglia P, Graniero KD. Some important details in the technique of percutaneous dilatational tracheostomy via the modified Seldinger technique. Chest 1996; 110:762.
  51. Díaz-Regañón G, Miñambres E, Ruiz A, et al. Safety and complications of percutaneous tracheostomy in a cohort of 800 mixed ICU patients. Anaesthesia 2008; 63:1198.
  52. Seder DB, Lee K, Rahman C, et al. Safety and feasibility of percutaneous tracheostomy performed by neurointensivists. Neurocrit Care 2009; 10:264.
  53. Freeman BD, Isabella K, Lin N, Buchman TG. A meta-analysis of prospective trials comparing percutaneous and surgical tracheostomy in critically ill patients. Chest 2000; 118:1412.
  54. Friedman Y, Fildes J, Mizock B, et al. Comparison of percutaneous and surgical tracheostomies. Chest 1996; 110:480.
  55. Silvester W, Goldsmith D, Uchino S, et al. Percutaneous versus surgical tracheostomy: A randomized controlled study with long-term follow-up. Crit Care Med 2006; 34:2145.
  56. Hazard P, Jones C, Benitone J. Comparative clinical trial of standard operative tracheostomy with percutaneous tracheostomy. Crit Care Med 1991; 19:1018.
  57. Holdgaard HO, Pedersen J, Jensen RH, et al. Percutaneous dilatational tracheostomy versus conventional surgical tracheostomy. A clinical randomised study. Acta Anaesthesiol Scand 1998; 42:545.
  58. Delaney A, Bagshaw SM, Nalos M. Percutaneous dilatational tracheostomy versus surgical tracheostomy in critically ill patients: a systematic review and meta-analysis. Crit Care 2006; 10:R55.
  59. Dempsey GA, Morton B, Hammell C, et al. Long-Term Outcome Following Tracheostomy in Critical Care: A Systematic Review. Crit Care Med 2016; 44:617.
  60. Gobatto AL, Besen BA, Tierno PF, et al. Ultrasound-guided percutaneous dilational tracheostomy versus bronchoscopy-guided percutaneous dilational tracheostomy in critically ill patients (TRACHUS): a randomized noninferiority controlled trial. Intensive Care Med 2016; 42:342.
  61. Yavuz A, Yılmaz M, Göya C, et al. Advantages of US in percutaneous dilatational tracheostomy: randomized controlled trial and review of the literature. Radiology 2014; 273:927.
  62. Gadkaree SK, Schwartz D, Gerold K, Kim Y. Use of Bronchoscopy in Percutaneous Dilational Tracheostomy. JAMA Otolaryngol Head Neck Surg 2016; 142:143.
  63. Trottier SJ, Hazard PB, Sakabu SA, et al. Posterior tracheal wall perforation during percutaneous dilational tracheostomy: an investigation into its mechanism and prevention. Chest 1999; 115:1383.
  64. Brass P, Hellmich M, Ladra A, et al. Percutaneous techniques versus surgical techniques for tracheostomy. Cochrane Database Syst Rev 2016; 7:CD008045.
  65. Kettunen WW, Helmer SD, Haan JM. Incidence of overall complications and symptomatic tracheal stenosis is equivalent following open and percutaneous tracheostomy in the trauma patient. Am J Surg 2014; 208:770.
  66. Dulguerov P, Gysin C, Perneger TV, Chevrolet JC. Percutaneous or surgical tracheostomy: a meta-analysis. Crit Care Med 1999; 27:1617.
  67. Warren WH. Percutaneous dilational tracheostomy: a note of caution. Crit Care Med 2000; 28:1664.
  68. El Solh AA, Jaafar W. A comparative study of the complications of surgical tracheostomy in morbidly obese critically ill patients. Crit Care 2007; 11:R3.
  69. Kluge S, Meyer A, Kühnelt P, et al. Percutaneous tracheostomy is safe in patients with severe thrombocytopenia. Chest 2004; 126:547.
  70. Meyer M, Critchlow J, Mansharamani N, et al. Repeat bedside percutaneous dilational tracheostomy is a safe procedure. Crit Care Med 2002; 30:986.
  71. Heyrosa MG, Melniczek DM, Rovito P, Nicholas GG. Percutaneous tracheostomy: a safe procedure in the morbidly obese. J Am Coll Surg 2006; 202:618.
  72. Drendel M, Primov-Fever A, Talmi YP, et al. Outcome of tracheostomy in patients over 85 years old (oldest-old patients). Otolaryngol Head Neck Surg 2009; 140:395.
  73. Shah S, Morgan P. Percutaneous dilation tracheostomy during high-frequency oscillatory ventilation. Crit Care Med 2002; 30:1762.
  74. Beiderlinden M, Groeben H, Peters J. Safety of percutaneous dilational tracheostomy in patients ventilated with high positive end-expiratory pressure (PEEP). Intensive Care Med 2003; 29:944.
  75. Beiderlinden M, Eikermann M, Lehmann N, et al. Risk factors associated with bleeding during and after percutaneous dilational tracheostomy. Anaesthesia 2007; 62:342.
  76. Hazelton JP, Orfe EC, Colacino AM, et al. The impact of a multidisciplinary safety checklist on adverse procedural events during bedside bronchoscopy-guided percutaneous tracheostomy. J Trauma Acute Care Surg 2015; 79:111.
  77. Reilly PM, Sing RF, Giberson FA, et al. Hypercarbia during tracheostomy: a comparison of percutaneous endoscopic, percutaneous Doppler, and standard surgical tracheostomy. Intensive Care Med 1997; 23:859.
  78. Ferraro F, Capasso A, Troise E, et al. Assessment of ventilation during the performance of elective endoscopic-guided percutaneous tracheostomy: clinical evaluation of a new method. Chest 2004; 126:159.
  79. Friedman Y, Mayer AD. Bedside percutaneous tracheostomy in critically ill patients. Chest 1993; 104:532.
  80. Steele AP, Evans HW, Afaq MA, et al. Long-term follow-up of Griggs percutaneous tracheostomy with spiral CT and questionnaire. Chest 2000; 117:1430.
  81. Johnson JL, Cheatham ML, Sagraves SG, et al. Percutaneous dilational tracheostomy: a comparison of single- versus multiple-dilator techniques. Crit Care Med 2001; 29:1251.
  82. Beiderlinden M, Karl Walz M, Sander A, et al. Complications of bronchoscopically guided percutaneous dilational tracheostomy: beyond the learning curve. Intensive Care Med 2002; 28:59.
  83. Byhahn C, Westphal K, Meininger D, et al. Single-dilator percutaneous tracheostomy: a comparison of PercuTwist and Ciaglia Blue Rhino techniques. Intensive Care Med 2002; 28:1262.
  84. Winkler WB, Karnik R, Seelmann O, et al. Bedside percutaneous dilational tracheostomy with endoscopic guidance: experience with 71 ICU patients. Intensive Care Med 1994; 20:476.
  85. Hazard PB. Further refinement of percutaneous tracheostomy technique. Intensive Care Med 1994; 20:466.
  86. Dollner R, Verch M, Schweiger P, et al. Laryngotracheoscopic findings in long-term follow-up after Griggs tracheostomy. Chest 2002; 122:206.
  87. Datta D, Onyirimba F, McNamee MJ. The utility of chest radiographs following percutaneous dilatational tracheostomy. Chest 2003; 123:1603.
  88. Nieszkowska A, Combes A, Luyt CE, et al. Impact of tracheotomy on sedative administration, sedation level, and comfort of mechanically ventilated intensive care unit patients. Crit Care Med 2005; 33:2527.
  89. Frutos-Vivar F, Esteban A, Apezteguía C, et al. Outcome of mechanically ventilated patients who require a tracheostomy. Crit Care Med 2005; 33:290.
  90. Combes A, Luyt CE, Nieszkowska A, et al. Is tracheostomy associated with better outcomes for patients requiring long-term mechanical ventilation? Crit Care Med 2007; 35:802.
  91. Kollef MH, Ahrens TS, Shannon W. Clinical predictors and outcomes for patients requiring tracheostomy in the intensive care unit. Crit Care Med 1999; 27:1714.
  92. Freeman BD, Borecki IB, Coopersmith CM, Buchman TG. Relationship between tracheostomy timing and duration of mechanical ventilation in critically ill patients. Crit Care Med 2005; 33:2513.
  93. Clec'h C, Alberti C, Vincent F, et al. Tracheostomy does not improve the outcome of patients requiring prolonged mechanical ventilation: a propensity analysis. Crit Care Med 2007; 35:132.
  94. Engoren M, Arslanian-Engoren C, Fenn-Buderer N. Hospital and long-term outcome after tracheostomy for respiratory failure. Chest 2004; 125:220.
  95. Trottier SJ, Ritter S, Lakshmanan R, et al. Percutaneous tracheostomy tube obstruction: warning. Chest 2002; 122:1377.
  96. Schmidt U, Hess D, Kwo J, et al. Tracheostomy tube malposition in patients admitted to a respiratory acute care unit following prolonged ventilation. Chest 2008; 134:288.
  97. Fikkers BG, van Veen JA, Kooloos JG, et al. Emphysema and pneumothorax after percutaneous tracheostomy: case reports and an anatomic study. Chest 2004; 125:1805.
  98. Polderman KH, Spijkstra JJ, de Bree R, et al. Percutaneous dilatational tracheostomy in the ICU: optimal organization, low complication rates, and description of a new complication. Chest 2003; 123:1595.
  99. Rumbak MJ, Walsh FW, Anderson WM, et al. Significant tracheal obstruction causing failure to wean in patients requiring prolonged mechanical ventilation: a forgotten complication of long-term mechanical ventilation. Chest 1999; 115:1092.
  100. Zias N, Chroneou A, Tabba MK, et al. Post tracheostomy and post intubation tracheal stenosis: report of 31 cases and review of the literature. BMC Pulm Med 2008; 8:18.
  101. Gelbard A, Francis DO, Sandulache VC, et al. Causes and consequences of adult laryngotracheal stenosis. Laryngoscope 2015; 125:1137.
  102. Koitschev A, Graumueller S, Zenner HP, et al. Tracheal stenosis and obliteration above the tracheostoma after percutaneous dilational tracheostomy. Crit Care Med 2003; 31:1574.
  103. Scalise P, Prunk SR, Healy D, Votto J. The incidence of tracheoarterial fistula in patients with chronic tracheostomy tubes: a retrospective study of 544 patients in a long-term care facility. Chest 2005; 128:3906.
  104. Jones JW, Reynolds M, Hewitt RL, Drapanas T. Tracheo-innominate artery erosion: Successful surgical management of a devastating complication. Ann Surg 1976; 184:194.
  105. Arola MK. Tracheostomy and its complications. A retrospective study of 794 tracheostomized patients. Ann Chir Gynaecol 1981; 70:96.
  106. Wood DE, Mathisen DJ. Late complications of tracheotomy. Clin Chest Med 1991; 12:597.
  107. Freeman-Sanderson A, Togher L, Phipps P, Elkins M. A clinical audit of the management of patients with a tracheostomy in an Australian tertiary hospital intensive care unit: Focus on speech-language pathology. Int J Speech Lang Pathol 2011; 13:518.
  108. Freeman-Sanderson AL, Togher L, Elkins MR, Phipps PR. Return of Voice for Ventilated Tracheostomy Patients in ICU: A Randomized Controlled Trial of Early-Targeted Intervention. Crit Care Med 2016; 44:1075.
  109. Pandian V, Smith CP, Cole TK, et al. Optimizing Communication in Mechanically Ventilated Patients. J Med Speech Lang Pathol 2014; 21:309.
  110. Kunduk M, Appel K, Tunc M, et al. Preliminary report of laryngeal phonation during mechanical ventilation via a new cuffed tracheostomy tube. Respir Care 2010; 55:1661.
  111. Cordes SR, Best AR, Hiatt KK. The impact of obesity on adult tracheostomy complication rate. Laryngoscope 2015; 125:105.
  112. White AC, Kher S, O'Connor HH. When to change a tracheostomy tube. Respir Care 2010; 55:1069.
  113. Fisher DF, Kondili D, Williams J, et al. Tracheostomy tube change before day 7 is associated with earlier use of speaking valve and earlier oral intake. Respir Care 2013; 58:257.
  114. Mitchell RB, Hussey HM, Setzen G, et al. Clinical consensus statement: tracheostomy care. Otolaryngol Head Neck Surg 2013; 148:6.
  115. O'Connor HH, White AC. Tracheostomy decannulation. Respir Care 2010; 55:1076.
  116. Bach JR, Saporito LR. Criteria for extubation and tracheostomy tube removal for patients with ventilatory failure. A different approach to weaning. Chest 1996; 110:1566.
  117. Ceriana P, Carlucci A, Navalesi P, et al. Weaning from tracheotomy in long-term mechanically ventilated patients: feasibility of a decisional flowchart and clinical outcome. Intensive Care Med 2003; 29:845.
  118. Heffner JE. The technique of weaning from tracheostomy. Criteria for weaning; practical measures to prevent failure. J Crit Illn 1995; 10:729.
  119. Budweiser S, Baur T, Jörres RA, et al. Predictors of successful decannulation using a tracheostomy retainer in patients with prolonged weaning and persisting respiratory failure. Respiration 2012; 84:469.
  120. Le HL, Aten JL, Chiang JT, et al . Comparison between conventional cap and one-way valve in the decannulation of patients with long-term tracheostomies. Respir Care 1993; 38:1161.
  121. Law JH, Barnhart K, Rowlett W, et al. Increased frequency of obstructive airway abnormalities with long-term tracheostomy. Chest 1993; 104:136.
  122. Rumbak MJ, Graves AE, Scott MP, et al. Tracheostomy tube occlusion protocol predicts significant tracheal obstruction to air flow in patients requiring prolonged mechanical ventilation. Crit Care Med 1997; 25:413.