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作者：Laurie Barclay, MD  
出處：WebMD醫學新聞

　　April 20, 2010 — 根據發表於4月21日美國醫學會期刊(Journal of the American Medical Association)的隨機控制試驗結果，對於加護病房(ICU)成人病患，提早進行氣管切開術(使用機械輔助呼吸之後6-8天)並不會比後來進行氣管切開術(使用機械輔助呼吸之後13-15天)更顯著降低呼吸器相關肺炎。
　　
　　義大利杜林di Torino大學Pier Paolo Terragni醫師等人寫道，氣管切開術被用來取代需要延長使用呼吸器患者的氣管插管，不過，對於進行氣管切開術的適當時機有值得考量的差異。這有臨床重要性，因為時機是進行氣管切開術的關鍵準則，進行此手術之病患需要大量的健康照護資源。
　　
　　研究目標是比較提早進行氣管切開術和後來進行氣管切開術的肺炎發生率，以及不必使用呼吸器和不用住在ICU的天數。
　　
　　從2004年6月至2008年6月，總共有來自義大利12個ICU的600名成人病患納入研究。納入規範是沒有肺部感染、使用呼吸器24小時、簡明急性生理功能評分方法第二版(Simplified Acute Physiology Score II) 分數介於35-65分，後續的器官衰竭評估分數至少5分。呼吸狀況惡化、後續器官衰竭評估分數未改變或惡化、納入之後48小時沒有發生肺炎，被指定到提早或延後氣管切開術。隨機指派到提早氣管切開術的209名病患中，145人接受氣管切開術，隨機指派到延後進行的210人中有119人接受。
　　
　　主要研究結果為呼吸器相關肺炎發生率；次級結果是在指定分組之後28天，不必使用呼吸器的天數、不用住ICU的天數、每組存活病患人數。
　　
　　在提早氣管切開術組中，有30名病患發生呼吸器相關肺炎(14%；95%信心區間[CI]，10%-19%)，延後進行氣管切開術組有44人(21%；95% CI，15%-26%；P = .07)。
　　
　　隨機分組之後28天的呼吸器相關肺炎風險比(HR)是0.66(95% CI，0.42 - 1.04)，在這段期間，繼續使用呼吸器的風險比是0.70(95% CI，0.56 - 0.87)；繼續住在ICU的風險比是0.73(95% CI，0.55 - 0.97)；死亡風險比則是0.80 (95% CI，0.56 - 1.15)。
　　
　　研究作者寫道，在使用機械輔助呼吸的成人ICU病患中，相較於延後進行氣管切開術，提早氣管切開術不會顯著改善呼吸器相關肺炎發生率、不必使用呼吸器的天數和不用住ICU的天數。相較於延後進行氣管切開術，提早氣管切開術組成功停止使用呼吸器，和從加護病房出院的發生率顯著較高；兩組在28天時的存活沒有差異。
　　
　　研究限制是，延後進行氣管切開術組觀察到的呼吸器相關肺炎發生率低於預期，導致統計強度降低，此外，隨機指派到提早進行氣管切開術和延後進行氣管切開術的病患，分別只有69%和57%的病患實際接受氣管切開術。
　　
　　研究作者們結論表示，基於1週時接受氣管切開術的病患數增加，超過三分之一病患發生氣管切開術相關副作用，這些資料認為，不應在氣管插管後13 -15天之前進行氣管切開術。
　　
　　【編輯評論：研究對象很重要】
　　加拿大多倫多Sunnybrook健康科學中心的Damon C. Scales博士以及加拿大多倫多Mount Sinai醫院與大學健康網絡的Niall D. Ferguson醫師在編輯評論中指出，在ICU進行隨機控制試驗時，正確定義研究對象很重要。
　　
　　Scales博士以及Ferguson醫師寫道，他們對於哪些病患需要延長機械輔助呼吸的演算是採主動提出，可能可以納入臨床實務來幫助預測，這個試驗應說服醫師，固定提早進行氣管切開術多數並不會減少VAP [呼吸器相關肺炎]、也不會縮短住院天數或降低死亡率，更重要的是，它顯示，進行氣管切開術對於察覺脫離呼吸器失敗必須是適當的，許多病患隨著時間將可有所改善，有時候醫師只需要觀察等待。
　　
　　Regione Piemonte Ricerca Sanitaria Finalizzata支持本研究，研究作者們與編輯皆宣告沒有相關財務關係。


Early vs Late Tracheotomy May Not Lower Ventilator-Associated Pneumonia Risk

By Laurie Barclay, MD
Medscape Medical News

April 20, 2010 — Early vs late tracheotomy (6 - 8 days vs 13 - 15 days after mechanical ventilation) may not significantly lower the risk for ventilator-associated pneumonia in adult patients in the intensive care unit (ICU), according to the results of a randomized controlled trial reported in the April 21 issue of the Journal of the American Medical Association.

"Tracheotomy is used to replace endotracheal intubation in patients requiring prolonged ventilation; however, there is considerable variability in the time considered optimal for performing tracheotomy," write Pier Paolo Terragni, MD, from Universita di Torino in Turin, Italy, and colleagues. "This is of clinical importance because timing is a key criterion for performing a tracheotomy and patients who receive one require a large amount of health care resources."

The goal of this study was to compare early tracheotomy vs late tracheotomy in the incidence of pneumonia and the number of ventilator-free and ICU-free days.

From June 2004 to June 2008, a total of 600 adult patients were enrolled from 12 Italian ICUs. Inclusion criteria were absence of lung infection, 24-hour duration of ventilation, a Simplified Acute Physiology Score II between 35 and 65, and a sequential organ failure assessment score of at least 5. Patients with worsening of respiratory conditions, an unchanged or worse sequential organ failure assessment score, and lack of pneumonia 48 hours after enrollment were assigned to early or late tracheotomy. Of 209 patients randomly assigned to early tracheotomy, 145 received tracheotomy, as did 119 of 210 randomly assigned to late tracheotomy.

The incidence of ventilator-associated pneumonia was the main study outcome. During the 28 days immediately after group assignment, secondary outcomes were the number of ventilator-free days, number of ICU-free days, and number of surviving patients in each group.

In the early tracheotomy group, ventilator-associated pneumonia developed in 30 patients (14%; 95% confidence interval [CI], 10% - 19%) and in 44 patients in the late tracheotomy group (21%; 95% CI, 15% - 26%; P = .07).

The hazard ratio (HR) for ventilator-associated pneumonia during the 28 days immediately after randomization was 0.66 (95% CI, 0.42 - 1.04). During the same period, the HR for remaining connected to the ventilator was 0.70 (95% CI, 0.56 - 0.87); for remaining in the ICU, 0.73 (95% CI, 0.55 - 0.97); and for death, 0.80 (95% CI, 0.56 - 1.15).

"Among mechanically ventilated adult ICU patients, early tracheotomy compared with late tracheotomy did not result in statistically significant improvement in incidence of ventilator-associated pneumonia," the study authors write. "The numbers of ventilator-free and ICU-free days and the incidences of successful weaning and ICU discharge were significantly greater in patients randomized to the early tracheotomy group compared with patients randomized to the late tracheotomy group; there were no differences between the groups in survival at 28 days."

Limitations of this study were that the observed incidence of ventilator-associated pneumonia in the late tracheotomy group was lower than predicted, resulting in loss of statistical power. In addition, only 69% of patients randomly assigned to the early tracheotomy group and 57% of patients randomly assigned to the late tracheotomy group actually received a tracheotomy.

"Considering that anticipation for tracheotomy of 1 week increased the number of patients who received a tracheotomy, and more than one-third of the patients experienced an adverse event related to tracheotomy, these data suggest that a tracheotomy should not be performed earlier than after 13 to 15 days of endotracheal intubation," the study authors conclude.

Editorial: Target Population Important

In an accompanying editorial, Damon C. Scales, MD, PhD, from the Sunnybrook Health Sciences Centre, Toronto, and Niall D. Ferguson, MD, MSc, from the University Health Network and Mount Sinai Hospital in Toronto, Canada, note the importance of correctly defining the target population when performing randomized controlled trials in the ICU.

"Their algorithm for predicting which patients will require prolonged mechanical ventilation is a step forward, and could be adopted into clinical practice to help with prognostication," Drs. Scales and Ferguson write. "This trial should convince clinicians that routine early tracheotomy most likely will not lead to reduced VAP [ventilator-associated pneumonia], shorter hospital stay, or lower mortality. Most importantly, it shows that performing tracheotomy for perceived weaning failure must be tempered by the knowledge that many patients will improve with additional time. Sometimes physicians just need to wait."

The Regione Piemonte Ricerca Sanitaria Finalizzata supported this study. The study authors and editorialists have disclosed no relevant financial relationships.

JAMA. 2010;303:1483-1489; 1537-1538.