Systematic review and meta-analysis of studies of the timing of trache
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《英国医生杂志》
1 Adult Intensive Care Unit, John Radcliffe Hospital, Oxford OX3 9DU, 2 Nuffield Department of Anaesthetics, University of Oxford, John Radcliffe Hospital
Correspondence to: J Duncan Young duncan.young@nda.ox.ac.uk
Objective To compare outcomes in critically ill patients undergoing artificial ventilation who received a tracheostomy early or late in their treatment.
Data sources The Cochrane Central Register of Clinical Trials, Medline, Embase, CINAHL, the National Research Register, the NHS Trusts Clinical Trials Register, the Medical Research Council UK database, the NHS Research and Development Health Technology Assessment Programme, the British Heart Foundation database, citation review of relevant primary and review articles, and expert informants.
Study selection Randomised and quasi-randomised controlled studies that compared early tracheostomy with either late tracheostomy or prolonged endotracheal intubation. From 15 950 articles screened, 12 were identified as "randomised or quasi-randomised" controlled trials, and five were included for data extraction.
Data extraction Five studies with 406 participants were analysed. Descriptive and outcome data were extracted. The main outcome measure was mortality in hospital. The incidence of hospital acquired pneumonia, length of stay in a critical care unit, and duration of artificial ventilation were also recorded. Random effects meta-analyses were performed.
Results Early tracheostomy did not significantly alter mortality (relative risk 0.79, 95% confidence interval 0.45 to 1.39). The risk of pneumonia was also unaltered by the timing of tracheostomy (0.90, 0.66 to 1.21). Early tracheostomy significantly reduced duration of artificial ventilation (weighted mean difference –8.5 days, 95% confidence interval –15.3 to –1.7) and length of stay in intensive care (–15.3 days, –24.6 to –6.1).
Conclusions In critically ill adult patients who require prolonged mechanical ventilation, performing a tracheostomy at an earlier stage than is currently practised may shorten the duration of artificial ventilation and length of stay in intensive care.
Tracheostomy is among the most commonly conducted procedures in critically ill patients. It has many potential advantages over translaryngeal endotracheal intubation in the critical care setting, including reduced laryngeal ulceration and respiratory resistance; it is better tolerated by patients and improves their capacity to communicate; and it makes for easier nursing care.1–4 However, the procedure is not without risk. Complications resulting from the procedure include stomal infections, stomal haemorrhage, pneumomediastinum, pneumothorax, and occasionally death.5–8 Although the procedure used to create a tracheostomy does not influence outcome, as both surgical and percutaneous techniques carry comparable modest risks, the effect the timing of the procedure has on outcome is less clear.9–11
Evidence to guide practice has been limited. In 1989 the National Association of Medical Directors of Respiratory Care recommended that translaryngeal (endotracheal) intubation be used only for patients requiring less than 10 days of artificial ventilation and that a tracheostomy should be placed in patients who still require artificial ventilation 21 days after admission.12 Although these recommendations are based only on expert opinion, modern practice broadly seems to follow them.13 In 1997 Kane et al recommended early tracheostomy in patients with multiple injuries on the basis of a descriptive review of the relevant literature,14 but a systematic review (without meta-analysis) of randomised trials of tracheostomy timing published in 1998 by Maziak et al concluded that there was insufficient evidence to support the view that the timing of tracheostomy alters the duration of mechanical ventilation or extent of airway injury in critically ill patients.15 Since the review by Maziak et al we are aware that at least two more trials have been completed, both of which were methodologically more sound than their predecessors.16 17 We decided to appraise critically and summarise all randomised clinical trials involving the timing of tracheostomy in adult patients in intensive care units.
Methods
We defined a randomised trial as one in which patients were assigned prospectively to either early tracheostomy or late (or no) tracheostomy by random allocation at time of enrolment. We defined early tracheostomy as a tracheostomy conducted up to seven days after admission to the intensive care unit, initiation of translaryngeal intubation, and mechanical ventilation. Late tracheostomy was any time thereafter.
We used several techniques to identify published and ongoing studies for this review. We searched Medline, CINAHL, Embase, the Cochrane Central Resister of Clinical Trials, the National Research Register, the NHS Trusts Clinical Trials Register, the Medical Research Council UK database, the NHS Research and Development Health Technology Assessment Programme, and the British Heart Foundation database in January, May, and November 2004. The search strategies for Medline were based on the terms recommended by the Cochrane Collaboration to identify randomised trials coupled with the term "trache*" to identify tracheostomies. We identified relevant studies initially by title, then by , and finally by full text. Initially two authors did the electronic searches in duplicate and then repeated them independently. We also searched the bibliographies of reports of randomised trials and any identified reviews. Finally we contacted UK experts in the subject.
Study selection and data extraction
We selected studies for inclusion in the analysis if they were randomised or quasi-randomised clinical trials including adult patients requiring artificial ventilation. The intervention was early tracheostomy, compared with either continued translaryngeal intubation or continued translaryngeal intubation followed by late tracheostomy. The primary outcome measure in the review was mortality; secondary outcomes were length of stay in the critical care unit, duration of artificial ventilation, and incidence of ventilator associated pneumonia. We combined hospital and 30 day mortality in the analysis, and if the point at which mortality was assessed was not given we assumed it to be hospital mortality. Not all studies included all outcome measures.
Statistics and analysis
We recorded mortality and the presence of hospital acquired pneumonia at any time in the study period as binary variables and length of stay in the critical care unit and duration of artificial ventilation as continuous variables. We used a random effects meta-analysis with RevMan 4.1 software (Cochrane Collaboration, Oxford) to analyse the data. We considered I2 > 50% to indicate significant heterogeneity between the trials.
Results
The initial searches identified 15 950 unique titles. After initial screening by title and then , we identified 12 randomised clinical trials from manuscript review. We excluded studies without either an English title or . We also identified one study from a published conference .18 We did not find any further relevant publications by reviewing the bibliography of the selected studies and review articles.
We then excluded two of the randomised studies because the timing of early and late tracheostomy were separated only by a 24 hour period,19 20 another because the timing of the early tracheostomy was after seven days (a criterion of this review),18 and a further two because the articles did not contain any data on the outcome measures on which this review is based.5 21 We excluded another study because of clear evidence of bias either in the selection of patients or their exclusion after randomisation, as a 1:1 randomisation schedule resulted in an approximately 5:1 final distribution of patients between study arms.22 Finally we excluded another study as it described only the study design.23 Figure 1 shows the search process.
Fig 1 Process of study selection of randomised controlled trials
Overall, only five trials with a combined study population of 406 patients were original, randomised or quasi-randomised, methodologically sound clinical trials of the timing of tracheostomy in the management of artificially ventilated, critically ill adults. These studies spanned a 20 year period between 1984 and 2004. One of the studies compared tracheostomy only with continuing translaryngeal intubation.24
Table 1 summarises the study characteristics. The two oldest studies25 26 were quasi-randomised, using randomisation techniques that allowed the assignment of the patient to be determined before enrolment, thereby producing a potential for bias. The studies by Saffle et al and Rumbak et al were appropriately randomised.16 17 The most recent study was described as randomised but did not define its randomisation strategy.18 24
Table 1 Summary of studies included in systematic review
Each of the studies examined different populations of critically ill patients, in critical care units for surgical, trauma, and burns patients and one multicentre study in three medical critical care units. All studies came from the United States, with the exception of the Moroccan study of Bouderka et al.
Mortality
Information on hospital mortality was available for four of the five studies (332 patients). Figure 2 shows the random effects meta-analysis of relative risk of hospital mortality for early compared with late tracheostomy. The timing of tracheostomy did not alter mortality significantly (relative risk 0.79, 95% confidence interval 0.45 to 1.39, P = 0.42).
Fig 2 Random effects meta-analysis of relative risk (95% confidence interval) of mortality with early compared with late tracheostomy
Risk of hospital acquired pneumonia
Information on the number of patients developing hospital acquired pneumonia while in the intensive care unit was available for all five studies. Figure 3 shows the random effects meta-analysis of relative risk of hospital acquired pneumonia for early versus late tracheostomy. The risk of developing hospital acquired pneumonia was unchanged by tracheostomy timing (0.90, 0.66 to 1.21, P = 0.48).
Fig 3 Random effects meta-analysis of relative risk (95% confidence interval) of hospital acquired pneumonia with early compared with late tracheostomy
Duration of artificial ventilation
Information on the duration of artificial ventilation was available for four of the five studies (332 patients). Figure 4 shows the forest plot. The combined results showed duration of artificial ventilation to be significantly lower in the early tracheostomy group (weighted mean difference –8.5 days, 95% confidence interval –15.3 days to –1.7 days, P = 0.03).
Fig 4 Random effects meta-analysis of weighted mean difference (95% confidence interval) of duration of ventilation in days
Length of stay in the critical care unit
Information on the length of stay in a critical care unit was available for two of the five studies (226 patients). Figure 5 shows the forest plot. Overall the length of stay in the critical care unit was significantly lower in the early tracheostomy group (–15.3 days, –24.6 days to –6.1 days, P = 0.001).
Fig 5 Random effects meta-analysis of weighted mean difference (95% confidence interval) of length of stay in the critical care unit in days
Discussion
Heffner JE. Timing of tracheotomy in mechanically ventilated patients. Am Rev Respir Dis 1993;147: 768-71.
Pelosi P, Severgnini P. Tracheostomy must be individualized! Crit Care 2004;8: 322-4.
Byhahn C, Wilke HJ, Lischke V, Westphal K. Translaryngeal tracheostomy: two modified techniques versus the basic technique--early experience in 75 critically ill adults. Intens Care Med 2000;26: 457-61.
Qureshi AI, Suarez JI, Parekh PD, Bhardwaj A. Prediction and timing of tracheostomy in patients with infratentorial lesions requiring mechanical ventilatory support. Crit Care Med 2000;28: 1383-7.
Stauffer JL, Olson DE, Petty TL. Complications and consequences of endotracheal intubation and tracheotomy. A prospective study of 150 critically ill adult patients. Am J Med 1981;70: 65-76.
Skaggs JA, Cogbill CL. Tracheostomy: management, mortality, complications. Am Surg 1969;35: 393-6.
Shlugman D, Satya-Krishna R, Loh L. Acute fatal haemorrhage during percutaneous dilatational tracheostomy. Br J Anaesth 2003;90: 517-20.
Ryan DW, Kilner AJ. Another death after percutaneous dilational tracheostomy. Br J Anaesth 2003;91: 925-6.
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: 1412-8.
Graham JS, Mulloy RH, Sutherland FR, Rose S. Percutaneous versus open tracheostomy: a retrospective cohort outcome study. J Trauma 1996;41: 245-8.
Boynton JH, Hawkins K, Eastridge BJ, O'Keefe GE. Tracheostomy timing and the duration of weaning in patients with acute respiratory failure. Crit Care 2004;8: R261-7.
Plummer AL, Gracey DR. Consensus conference on artificial airways in patients receiving mechanical ventilation. Chest 1989;96: 178-80.
Fischler L, Erhart S, Kleger GR, Frutiger A. Prevalence of tracheostomy in ICU patients. A nation-wide survey in Switzerland. Intens Care Med 2000;26: 1428-33.
Kane TD, Rodriguez JL, Luchette FA. Early versus late tracheostomy in the trauma patient. Respir Care Clin N Am 1997;3: 1-20.
Maziak DE, Meade MO, Todd TR. The timing of tracheotomy: a systematic review. Chest 1998;114: 605-9.
Saffle JR, Morris SE, Edelman L. Early tracheostomy does not improve outcome in burn patients. J Burn Care Rehabil 2002;23: 431-8.
Rumbak MJ, Newton M, Truncale T, Schwartz SW, Adams JW, Hazard PB. A prospective, randomized study comparing early percutaneous dilatational tracheostomy to prolonged translaryngeal intubation (delayed tracheostomy) in critically ill medical patients. Crit Care Med 2004;32: 1689-94.
Barquist E. A randomized prospective study of early vs late tracheostomy in trauma patients. Proceeding of the American Association for the Surgery of Trauma, 2004. www.aast.org/PDF/04absOral.pdf (accessed 10 May 2005).
Cheng DC, Karski J, Peniston C, Raveendran G, Asokumar B, Carroll J, et al. Early tracheal extubation after coronary artery bypass graft surgery reduces costs and improves resource use. A prospective, randomized, controlled trial. Anesthesiology 1996;85: 1300-10.
Quasha AL, Loeber N, Feeley TW, Ullyot DJ, Roizen MF. Postoperative respiratory care: a controlled trial of early and late extubation following coronary-artery bypass grafting. Anesthesiology 1980;52: 135-41.
El-Naggar M, Sadagopan S, Levine H, Kantor H, Collins VJ. Factors influencing choice between tracheostomy and prolonged translaryngeal intubation in acute respiratory failure: a prospective study. Anesth Analg 1976;55: 195-201.
Sugerman HJ, Wolfe L, Pasquale MD, Rogers FB, O'Malley KF, Knudson M, et al. Multicenter, randomized, prospective trial of early tracheostomy. J Trauma 1997;43: 741-7.
Blot F. . Rev Mal Respir 2003;20: 411-20. (In French.)
Bouderka MA, Fakhir B, Bouaggad A, Hmamouchi B, Hamoudi D, Harti A. Early tracheostomy versus prolonged endotracheal intubation in severe head injury. J Trauma 2004;57: 251-4.
Dunham CM, LaMonica C. Prolonged tracheal intubation in the trauma patient. J Trauma 1984;24: 120-4.
Rodriguez JL, Steinberg SM, Luchetti FA, Gibbons KJ, Taheri PA, Flint LM. Early tracheostomy for primary airway management in the surgical critical care setting. Surgery 1990;108: 655-9.
Higgins JPT, Thompson SG, Deeks JJ, Altman DG. Measuring inconsistency in meta-analyses. BMJ 2003;327: 557-60.
Sellers BJ, Davis BL, Larkin PW, Morris SE, Saffle JR. Early prediction of prolonged ventilator dependence in thermally injured patients. J Trauma 1997;43: 899-903.(John Griffiths, specialist registrar1, V)
Correspondence to: J Duncan Young duncan.young@nda.ox.ac.uk
Objective To compare outcomes in critically ill patients undergoing artificial ventilation who received a tracheostomy early or late in their treatment.
Data sources The Cochrane Central Register of Clinical Trials, Medline, Embase, CINAHL, the National Research Register, the NHS Trusts Clinical Trials Register, the Medical Research Council UK database, the NHS Research and Development Health Technology Assessment Programme, the British Heart Foundation database, citation review of relevant primary and review articles, and expert informants.
Study selection Randomised and quasi-randomised controlled studies that compared early tracheostomy with either late tracheostomy or prolonged endotracheal intubation. From 15 950 articles screened, 12 were identified as "randomised or quasi-randomised" controlled trials, and five were included for data extraction.
Data extraction Five studies with 406 participants were analysed. Descriptive and outcome data were extracted. The main outcome measure was mortality in hospital. The incidence of hospital acquired pneumonia, length of stay in a critical care unit, and duration of artificial ventilation were also recorded. Random effects meta-analyses were performed.
Results Early tracheostomy did not significantly alter mortality (relative risk 0.79, 95% confidence interval 0.45 to 1.39). The risk of pneumonia was also unaltered by the timing of tracheostomy (0.90, 0.66 to 1.21). Early tracheostomy significantly reduced duration of artificial ventilation (weighted mean difference –8.5 days, 95% confidence interval –15.3 to –1.7) and length of stay in intensive care (–15.3 days, –24.6 to –6.1).
Conclusions In critically ill adult patients who require prolonged mechanical ventilation, performing a tracheostomy at an earlier stage than is currently practised may shorten the duration of artificial ventilation and length of stay in intensive care.
Tracheostomy is among the most commonly conducted procedures in critically ill patients. It has many potential advantages over translaryngeal endotracheal intubation in the critical care setting, including reduced laryngeal ulceration and respiratory resistance; it is better tolerated by patients and improves their capacity to communicate; and it makes for easier nursing care.1–4 However, the procedure is not without risk. Complications resulting from the procedure include stomal infections, stomal haemorrhage, pneumomediastinum, pneumothorax, and occasionally death.5–8 Although the procedure used to create a tracheostomy does not influence outcome, as both surgical and percutaneous techniques carry comparable modest risks, the effect the timing of the procedure has on outcome is less clear.9–11
Evidence to guide practice has been limited. In 1989 the National Association of Medical Directors of Respiratory Care recommended that translaryngeal (endotracheal) intubation be used only for patients requiring less than 10 days of artificial ventilation and that a tracheostomy should be placed in patients who still require artificial ventilation 21 days after admission.12 Although these recommendations are based only on expert opinion, modern practice broadly seems to follow them.13 In 1997 Kane et al recommended early tracheostomy in patients with multiple injuries on the basis of a descriptive review of the relevant literature,14 but a systematic review (without meta-analysis) of randomised trials of tracheostomy timing published in 1998 by Maziak et al concluded that there was insufficient evidence to support the view that the timing of tracheostomy alters the duration of mechanical ventilation or extent of airway injury in critically ill patients.15 Since the review by Maziak et al we are aware that at least two more trials have been completed, both of which were methodologically more sound than their predecessors.16 17 We decided to appraise critically and summarise all randomised clinical trials involving the timing of tracheostomy in adult patients in intensive care units.
Methods
We defined a randomised trial as one in which patients were assigned prospectively to either early tracheostomy or late (or no) tracheostomy by random allocation at time of enrolment. We defined early tracheostomy as a tracheostomy conducted up to seven days after admission to the intensive care unit, initiation of translaryngeal intubation, and mechanical ventilation. Late tracheostomy was any time thereafter.
We used several techniques to identify published and ongoing studies for this review. We searched Medline, CINAHL, Embase, the Cochrane Central Resister of Clinical Trials, the National Research Register, the NHS Trusts Clinical Trials Register, the Medical Research Council UK database, the NHS Research and Development Health Technology Assessment Programme, and the British Heart Foundation database in January, May, and November 2004. The search strategies for Medline were based on the terms recommended by the Cochrane Collaboration to identify randomised trials coupled with the term "trache*" to identify tracheostomies. We identified relevant studies initially by title, then by , and finally by full text. Initially two authors did the electronic searches in duplicate and then repeated them independently. We also searched the bibliographies of reports of randomised trials and any identified reviews. Finally we contacted UK experts in the subject.
Study selection and data extraction
We selected studies for inclusion in the analysis if they were randomised or quasi-randomised clinical trials including adult patients requiring artificial ventilation. The intervention was early tracheostomy, compared with either continued translaryngeal intubation or continued translaryngeal intubation followed by late tracheostomy. The primary outcome measure in the review was mortality; secondary outcomes were length of stay in the critical care unit, duration of artificial ventilation, and incidence of ventilator associated pneumonia. We combined hospital and 30 day mortality in the analysis, and if the point at which mortality was assessed was not given we assumed it to be hospital mortality. Not all studies included all outcome measures.
Statistics and analysis
We recorded mortality and the presence of hospital acquired pneumonia at any time in the study period as binary variables and length of stay in the critical care unit and duration of artificial ventilation as continuous variables. We used a random effects meta-analysis with RevMan 4.1 software (Cochrane Collaboration, Oxford) to analyse the data. We considered I2 > 50% to indicate significant heterogeneity between the trials.
Results
The initial searches identified 15 950 unique titles. After initial screening by title and then , we identified 12 randomised clinical trials from manuscript review. We excluded studies without either an English title or . We also identified one study from a published conference .18 We did not find any further relevant publications by reviewing the bibliography of the selected studies and review articles.
We then excluded two of the randomised studies because the timing of early and late tracheostomy were separated only by a 24 hour period,19 20 another because the timing of the early tracheostomy was after seven days (a criterion of this review),18 and a further two because the articles did not contain any data on the outcome measures on which this review is based.5 21 We excluded another study because of clear evidence of bias either in the selection of patients or their exclusion after randomisation, as a 1:1 randomisation schedule resulted in an approximately 5:1 final distribution of patients between study arms.22 Finally we excluded another study as it described only the study design.23 Figure 1 shows the search process.
Fig 1 Process of study selection of randomised controlled trials
Overall, only five trials with a combined study population of 406 patients were original, randomised or quasi-randomised, methodologically sound clinical trials of the timing of tracheostomy in the management of artificially ventilated, critically ill adults. These studies spanned a 20 year period between 1984 and 2004. One of the studies compared tracheostomy only with continuing translaryngeal intubation.24
Table 1 summarises the study characteristics. The two oldest studies25 26 were quasi-randomised, using randomisation techniques that allowed the assignment of the patient to be determined before enrolment, thereby producing a potential for bias. The studies by Saffle et al and Rumbak et al were appropriately randomised.16 17 The most recent study was described as randomised but did not define its randomisation strategy.18 24
Table 1 Summary of studies included in systematic review
Each of the studies examined different populations of critically ill patients, in critical care units for surgical, trauma, and burns patients and one multicentre study in three medical critical care units. All studies came from the United States, with the exception of the Moroccan study of Bouderka et al.
Mortality
Information on hospital mortality was available for four of the five studies (332 patients). Figure 2 shows the random effects meta-analysis of relative risk of hospital mortality for early compared with late tracheostomy. The timing of tracheostomy did not alter mortality significantly (relative risk 0.79, 95% confidence interval 0.45 to 1.39, P = 0.42).
Fig 2 Random effects meta-analysis of relative risk (95% confidence interval) of mortality with early compared with late tracheostomy
Risk of hospital acquired pneumonia
Information on the number of patients developing hospital acquired pneumonia while in the intensive care unit was available for all five studies. Figure 3 shows the random effects meta-analysis of relative risk of hospital acquired pneumonia for early versus late tracheostomy. The risk of developing hospital acquired pneumonia was unchanged by tracheostomy timing (0.90, 0.66 to 1.21, P = 0.48).
Fig 3 Random effects meta-analysis of relative risk (95% confidence interval) of hospital acquired pneumonia with early compared with late tracheostomy
Duration of artificial ventilation
Information on the duration of artificial ventilation was available for four of the five studies (332 patients). Figure 4 shows the forest plot. The combined results showed duration of artificial ventilation to be significantly lower in the early tracheostomy group (weighted mean difference –8.5 days, 95% confidence interval –15.3 days to –1.7 days, P = 0.03).
Fig 4 Random effects meta-analysis of weighted mean difference (95% confidence interval) of duration of ventilation in days
Length of stay in the critical care unit
Information on the length of stay in a critical care unit was available for two of the five studies (226 patients). Figure 5 shows the forest plot. Overall the length of stay in the critical care unit was significantly lower in the early tracheostomy group (–15.3 days, –24.6 days to –6.1 days, P = 0.001).
Fig 5 Random effects meta-analysis of weighted mean difference (95% confidence interval) of length of stay in the critical care unit in days
Discussion
Heffner JE. Timing of tracheotomy in mechanically ventilated patients. Am Rev Respir Dis 1993;147: 768-71.
Pelosi P, Severgnini P. Tracheostomy must be individualized! Crit Care 2004;8: 322-4.
Byhahn C, Wilke HJ, Lischke V, Westphal K. Translaryngeal tracheostomy: two modified techniques versus the basic technique--early experience in 75 critically ill adults. Intens Care Med 2000;26: 457-61.
Qureshi AI, Suarez JI, Parekh PD, Bhardwaj A. Prediction and timing of tracheostomy in patients with infratentorial lesions requiring mechanical ventilatory support. Crit Care Med 2000;28: 1383-7.
Stauffer JL, Olson DE, Petty TL. Complications and consequences of endotracheal intubation and tracheotomy. A prospective study of 150 critically ill adult patients. Am J Med 1981;70: 65-76.
Skaggs JA, Cogbill CL. Tracheostomy: management, mortality, complications. Am Surg 1969;35: 393-6.
Shlugman D, Satya-Krishna R, Loh L. Acute fatal haemorrhage during percutaneous dilatational tracheostomy. Br J Anaesth 2003;90: 517-20.
Ryan DW, Kilner AJ. Another death after percutaneous dilational tracheostomy. Br J Anaesth 2003;91: 925-6.
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: 1412-8.
Graham JS, Mulloy RH, Sutherland FR, Rose S. Percutaneous versus open tracheostomy: a retrospective cohort outcome study. J Trauma 1996;41: 245-8.
Boynton JH, Hawkins K, Eastridge BJ, O'Keefe GE. Tracheostomy timing and the duration of weaning in patients with acute respiratory failure. Crit Care 2004;8: R261-7.
Plummer AL, Gracey DR. Consensus conference on artificial airways in patients receiving mechanical ventilation. Chest 1989;96: 178-80.
Fischler L, Erhart S, Kleger GR, Frutiger A. Prevalence of tracheostomy in ICU patients. A nation-wide survey in Switzerland. Intens Care Med 2000;26: 1428-33.
Kane TD, Rodriguez JL, Luchette FA. Early versus late tracheostomy in the trauma patient. Respir Care Clin N Am 1997;3: 1-20.
Maziak DE, Meade MO, Todd TR. The timing of tracheotomy: a systematic review. Chest 1998;114: 605-9.
Saffle JR, Morris SE, Edelman L. Early tracheostomy does not improve outcome in burn patients. J Burn Care Rehabil 2002;23: 431-8.
Rumbak MJ, Newton M, Truncale T, Schwartz SW, Adams JW, Hazard PB. A prospective, randomized study comparing early percutaneous dilatational tracheostomy to prolonged translaryngeal intubation (delayed tracheostomy) in critically ill medical patients. Crit Care Med 2004;32: 1689-94.
Barquist E. A randomized prospective study of early vs late tracheostomy in trauma patients. Proceeding of the American Association for the Surgery of Trauma, 2004. www.aast.org/PDF/04absOral.pdf (accessed 10 May 2005).
Cheng DC, Karski J, Peniston C, Raveendran G, Asokumar B, Carroll J, et al. Early tracheal extubation after coronary artery bypass graft surgery reduces costs and improves resource use. A prospective, randomized, controlled trial. Anesthesiology 1996;85: 1300-10.
Quasha AL, Loeber N, Feeley TW, Ullyot DJ, Roizen MF. Postoperative respiratory care: a controlled trial of early and late extubation following coronary-artery bypass grafting. Anesthesiology 1980;52: 135-41.
El-Naggar M, Sadagopan S, Levine H, Kantor H, Collins VJ. Factors influencing choice between tracheostomy and prolonged translaryngeal intubation in acute respiratory failure: a prospective study. Anesth Analg 1976;55: 195-201.
Sugerman HJ, Wolfe L, Pasquale MD, Rogers FB, O'Malley KF, Knudson M, et al. Multicenter, randomized, prospective trial of early tracheostomy. J Trauma 1997;43: 741-7.
Blot F. . Rev Mal Respir 2003;20: 411-20. (In French.)
Bouderka MA, Fakhir B, Bouaggad A, Hmamouchi B, Hamoudi D, Harti A. Early tracheostomy versus prolonged endotracheal intubation in severe head injury. J Trauma 2004;57: 251-4.
Dunham CM, LaMonica C. Prolonged tracheal intubation in the trauma patient. J Trauma 1984;24: 120-4.
Rodriguez JL, Steinberg SM, Luchetti FA, Gibbons KJ, Taheri PA, Flint LM. Early tracheostomy for primary airway management in the surgical critical care setting. Surgery 1990;108: 655-9.
Higgins JPT, Thompson SG, Deeks JJ, Altman DG. Measuring inconsistency in meta-analyses. BMJ 2003;327: 557-60.
Sellers BJ, Davis BL, Larkin PW, Morris SE, Saffle JR. Early prediction of prolonged ventilator dependence in thermally injured patients. J Trauma 1997;43: 899-903.(John Griffiths, specialist registrar1, V)