R E S E A R C H A R T I C L E
Open Access
Is tracheostomy a better choice than
translaryngeal intubation for critically ill
patients requiring mechanical ventilation
for more than 14 days? A comparison of
short-term outcomes
Wei-Chieh Lin
1*, Chang-Wen Chen
1, Jung-Der Wang
2and Liang-Miin Tsai
1Abstract
Background: Tracheostomy is recommended for patients receiving mechanical ventilation (MV) for 14 days or more in the intensive care unit (ICU). Nevertheless, many patients undergoing prolonged MV remain intubated via the translaryngeal route. The aim of this study was to examine the influence of tracheostomy and persistent translaryngeal intubation on short-term outcomes in patients mechanically ventilated for≥14 days.
Methods: A retrospective study was conducted using the admissions database of a 75-bed ICU from January 1, 2012, to December 31, 2012. Patients who required prolonged MV without tracheostomy at the time of initiation of a ventilator were included. The outcomes were successful weaning, and ICU and in-hospital death. Cox models were constructed to calculate the influence of tracheostomy on the outcome measures while adjusting for other potentially confounding factors.
Results: Of the 508 patients requiring prolonged MV, 164 were tracheostomized after a median 18 days of MV. Patients in whom translaryngeal intubation was maintained had significantly higher ICU (42.7 % versus 17.1 %, p <0.001) and in-hospital (54.1 % versus 22.0 %, p <0.001) mortality rates, and a significantly lower successful weaning rate (40.4 % versus 68.9 %, p <0.001). The results were consistent after matching for the propensity score of performing tracheostomy. Furthermore, a time-dependent covariate Cox model showed that a tracheostomy was independently associated with lower in-hospital mortality (adjusted hazard ratio [aHR], 0.26; 95 % confidence interval [CI], 0.18–0.39) and higher successful weaning rate (aHR, 2.05; 95 % CI, 1.56–2.68). Conclusions: Tracheostomy is associated with lower in-hospital mortality and higher successful weaning rates in ICU patients receiving prolonged MV. However, the cost-effectiveness and long-term outcomes of
tracheostomy for this cohort require further study.
Keywords: Intensive care unit, Mortality, Tracheostomy, Weaning, Prolonged mechanical ventilation
* Correspondence:wclin@mail.ncku.edu.tw
1Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, No. 138 Sheng-Li Road, Tainan 704, Taiwan
Full list of author information is available at the end of the article
© 2015 Lin et al. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
Background
The number of patients requiring prolonged mechanical ventilation (PMV) in the intensive care unit (ICU) is in-creasing [1]. These patients consume a substantial amount of healthcare resources [2] and most have poor short- and long-term outcomes [2, 3]. Tracheostomy is thought to provide several advantages over translaryn-geal intubation in patients undergoing PMV, such as the promotion of oral hygiene and pulmonary toilet, im-proved patient comfort, decreased airway resistance, ac-celerated weaning from mechanical ventilation (MV) [4], the ability to transfer ventilator-dependent patients from the ICU to step-down facilities [5] and a reduced risk of developing ventilator-associated pneumonia (VAP) [6]. Although tracheostomy is customarily performed to facilitate care of patients requiring PMV, physician prac-tices regarding tracheostomy differ widely [7]; further-more, a significant proportion of patients or family members decline to give consent for tracheostomy, even when long-term ventilator dependence is expected. The reported rates of tracheostomy range from 5–24 % and time to tracheostomy ranges from 9–12 days [8]. Three meta-analyses of studies examining the role of tracheos-tomy in critically ill patients receiving MV have failed to demonstrate any benefits of“early” tracheostomy on sur-vival, length of ICU or hospital stay, or duration of MV, compared with those undergoing “late” tracheostomy or prolonged translaryngeal intubation [9–11]. It is im-portant to note, however, that two of these studies
used ≤7 days after translaryngeal intubation as the
definition of “early” tracheostomy [10, 11], while the other used ≤10 days [9].
Consequently, most experts recommend that tracheos-tomy be deferred for at least 10–14 days after translaryn-geal intubation to ensure that ongoing MV is indeed required [4, 11, 12]. Currently, most clinicians view 1–2 weeks after intubation as the most appropriate timing for tracheostomy [9]. Nonetheless, many patients still undergo MV via a translaryngeal endotracheal tube for more than 2 weeks. We undertook a study to examine the outcomes of patients undergoing MV for at least 14 days in the ICU via persistent translaryngeal intub-ation or tracheostomy. We hypothesized that tracheos-tomy would be associated with an increased rate of successful weaning and reduced ICU and in-hospital mortality in critically ill patients requiring PMV com-pared with persistent translaryngeal intubation. The aim of this study was to evaluate the effect of tracheostomy on the outcome of patients receiving PMV (≥14 days) in our medical-surgical ICU.
Methods
Conduct of the study was approved by the ethics com-mittee of National Cheng Kung University Hospital
(reference A-ER-103-284-T). It was judged that the retrospective observational study design posed no risks to patients. The need for informed consent was waived, as all data were anonymized and patient identification numbers were encrypted.
Study design
This was a retrospective cohort study using anonymized data from an ICU clinical information system (IntelliVue Clinical Information Portfolio, Philips) derived from a single center. The database included vital signs and ven-tilation status recorded automatically from monitors and ventilators, laboratory data retrieved automatically from our hospital’s central laboratory report system, fluid bal-ance, and clinical and nursing procedures. Demographic data recorded routinely at ICU admission by supervising nurses included age, sex and the Acute Physiology and Chronic Health Evaluation II (APACHE II) score. Two analytical models were constructed: a multivariable time-dependent Cox model, and propensity score matching for performing tracheostomy that adjusted for potential con-founding factors to evaluate the effect of tracheostomy on the outcomes of patients with PMV.
Patients and setting
Data were obtained from patients admitted to the 75-bed adult ICU at the tertiary referral center of southern Taiwan between January 1, 2012, and December 31, 2012. Patients who were older than 16 years and
re-ceived MV ≥24 h were screened, those who underwent
MV for at least 14 days were included in the study. Patients with a tracheostomy present at the time of initi-ation of MV were excluded. For patients who had more
than one ICU admission with MV ≥14 days during the
study period, only the first admission was included in the analyses to avoid the potential selection bias of including patients without tracheostomy in whom the risk of death was higher.
In our clinical practice, tracheostomy is normally undertaken after an episode of failed extubation or rein-tubation, in the presence of unrelieved upper airway obstruction, when airway protection or regular pulmon-ary toilet is indicated, when PMV is needed, or for the avoidance of the complications of prolonged translaryn-geal intubation. All tracheostomies are formed surgically. The decision to perform a tracheostomy is at the discre-tion of the attending physician, but only after informed consent has been obtained from the patient, their next of kin or their legal representative.
Variables
Study variables included in the analyses were: age; sex; comorbidities; Charlson comorbidity index (CCI) score; APACHE II score within 24 h of ICU admission; ICU
type (medical or surgical ICU); presence of a do-not-resuscitate (DNR) order; time to tracheostomy (if per-formed); diagnosis at ICU admission; requirement for non-invasive ventilation (NIV) after extubation; duration of MV and successful weaning from MV; ICU and hos-pital lengths of stay; and ICU and in-hoshos-pital mortality. Laboratory data including blood urea nitrogen (BUN), serum creatinine concentration, blood gas analysis, and white blood cell (WBC) and platelet counts were re-corded. In this observational study, we could not mandate that routine laboratory tests be performed at particular times. We therefore recorded variables ob-tained on days 1 to 5 of ICU admission (week 1, w1) and days 8 to 12 (week 2, w2) to ensure that all data were available for the analyses. The least favorable value of each variable was chosen for analysis if more than two values existed within the same time period. ICU ad-mission diagnosis and comorbidities were identified ac-cording to the International Classification of Diseases, ninth revision and categorized as shown in the supple-mentary material (Additional file 1). Non-invasive venti-lation was initiated after extubation as needed, if it was judged that patients were at high risk of extubation fail-ure [13–16]. Successful weaning was recorded when MV was not required again after discontinuation during hospitalization, regardless of outcome.
Statistical analysis
We categorized the patients into a tracheostomy group and a translaryngeal tube group. Continuous variables are expressed as the mean ± standard deviation (SD), or the median and interquartile range (IQR). Categorical variables are expressed as frequencies and proportions (%). Continuous variables were compared with Student’s t test or the Mann–Whitney U test (for skewed data); categorical variables were compared with the chi-squared test or Fisher’s exact test, as necessary. Levels of significance are expressed as p values; p <0.05 was con-sidered statistically significant. Demographic, clinical and laboratory values were used to determine whether tracheostomy was independently associated with both in-hospital mortality and successful weaning. As the for-mation of a tracheostomy was considered to be a time-dependent covariate, a multivariable time-time-dependent Cox model was constructed. Median values were used to categorize continuous variables for Cox models. The fac-tors with a p value <0.1 in the univariate analysis, to-gether with age and sex regardless of the univariate p value, were entered in the Cox models. The results are presented as adjusted hazard ratios (aHR) with 95 % confidence intervals (CIs). The impact of tracheostomy on outcomes was assessed using a propensity score for a case-matched comparison to deal with significant het-erogeneity between patients undergoing tracheostomy or
persistent translaryngeal intubation in a retrospective cohort study (Table 1). The case-matched comparison was performed as previously described [17]. All univari-able predictors of tracheostomy with p <0.25 together with age and sex were entered into the multivariable model predicting tracheostomy. Stepwise logistic regres-sion was performed to remove covariates that had multi-variable p values of >0.25. A propensity score for undergoing tracheostomy was calculated for each patient using the coefficients of the final regression equation. Then, each tracheostomy patient was matched with a single translaryngeal intubated patient who had a similar propensity score (within 0.1 on a scale from 0 to 1). When more than one matched patient was identified for a case, the closest admission date was used to select the matched patient. We also performed a sensitivity ana-lysis using a more stringent propensity score matching within 0.05. The matched Wilcoxon test, the McNemar test, and mixed model or general estimation equations were used for case-match study comparisons. Analyses were performed using SPSS, version 20 for Windows (SPSS Inc., Chicago, IL, USA).
Results
MV was required for at least 24 h in 2,098 adult ICU ad-missions during the study period. Of these, 551 patients (26.3 %) who received MV for at least 14 days were screened, and those who already had a tracheostomy tube in situ at the initiation of MV were excluded. The remaining 508 patients were included in the analyses. During their ICU admission, 164 patients (32.3 %) underwent a tracheostomy. The remaining 344 patients (67.7 %) did not undergo a tracheostomy during hospitalization (Fig. 1). For those who received tracheos-tomy, the median time between endotracheal intubation and insertion of a tracheostomy tube was 18 days (IQR, 13–25 days). The overall ICU and in-hospital mortality rates were 34.4 % and 43.7 %, respectively.
The baseline characteristics of the study population are summarized in Table 1. A greater proportion of translaryngeal intubated patients were admitted to the medical ICU, had a current DNR order, had a higher CCI score, had chronic heart, liver or connective tissue disease, and required NIV after extubation, but a smaller proportion had brain disorders or had sustained trauma. There were no significant differences in the ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen (PaO2/FiO2), WBC count or platelet
count between the groups. The serum concentrations of BUN (w2) and creatinine (w1 and w2) were significantly lower in the tracheostomy group than the translaryngeal tube group.
Table 2 shows a comparison of the short-term out-comes between the groups. Compared with those with a
tracheostomy, translaryngeal intubated patients had sig-nificantly higher ICU (42.7 % versus 17.1 %, p <0.001) and in-hospital (54.1 % versus 22.0 %, p <0.001) mor-tality rates, lower weaning rate (40.4 % versus 68.9 %, p <0.001) and significantly shorter median duration of MV (26 days versus 37 days, p <0.001), ICU length of stay (25 days versus 40 days, p <0.001) and hospital length of stay (30 days versus 59 days, p <0.001). In addition, translaryngeal intubated patients were trans-ferred earlier to lower level regional hospitals com-pared with tracheostomized patients (28 days versus 54 days, p <0.001).
Multivariable time-dependent Cox regression model-ing showed that performmodel-ing a tracheostomy was associ-ated with a significantly lower risk of in-hospital death (aHR 0.26, 95 % CI 0.18–0.39, p <0.001) and a signifi-cantly higher chance of successful weaning (aHR 2.05, 95 % CI 1.56–2.68, p <0.001; Table 3). The other Table 1 Demographic and clinical characteristics of patients
mechanically ventilated for at least 14 days
Translaryngeal tube (n = 344) Tracheostomy (n = 164) p value Age, years 67 ± 14 62 ± 18 0.416 Male, n (%) 203 (59) 110 (67) 0.099 MICU, n (%) 237 (69) 70 (43) <0.001 APACHE II score 23.1 ± 7.8 23.2 ± 7.5 0.446 Do-not-resuscitate order, n (%) 157 (46) 39 (24) <0.001 NIV after extubation, n (%) 79 (23) 24 (15) 0.039 Diagnosis of ICU admission, n (%)
Pneumonia 190 (55) 94 (57) 0.729 Sepsis 164 (48) 68 (42) 0.223 Cardiovascular or vascular disorder 39 (11) 12 (7) 0.211 Trauma 20 (6) 23 (14) 0.003 Brain disorder 99 (29) 76 (46) <0.001 Burn 5 (2) 0 (0) 0.181 Gastrointestinal Disorder 103 (30) 51 (31) 0.872 CCI score 2 (1–3) 2 (0–3) 0.017 Comorbidities, n (%) Diabetes 121 (35) 66 (40) 0.313
Chronic lung disease 75 (22) 37 (23) 0.938 Chronic heart disease 91 (27) 29 (18) 0.039 Chronic liver disease 49 (14) 12 (7) 0.036 Chronic renal disease 91 (27) 30 (18) 0.056
Malignancy 107 (31) 44 (27) 0.378
Connective tissue disease 14 (4) 1 (1) 0.045 Neuromuscular disease 19 (6) 10 (6) 0.955 PaO2/FiO2 w1 290.9 ± 136.6 266.6 ± 132.0 0.245 w2 307.9 ± 101.2 293.6 ± 110.0 0.151 WBC (× 103/μl) w1 12.3 (9.6–16.6) 10.8 (8.4–15.9) 0.808 w2 10.5 (7.9–12.8) 11.5 (7.9–14.9) 0.638 Platelet (× 103/μl) w1 193.0 (129.0–233.0) 148.0 (102.5–195.3) 0.076 w2 181.0 (107.0–240.0) 143.0 (88.0–263.5) 0.066 BUN (mg/dl) w1 18.0 (13.0–40.0) 28.5 (14.3–49.8) 0.146 w2 35.0 (24.0–65.0) 44.0 (22.0–65.3) 0.025 Creatinine (mg/dl) w1 1.1 (0.8–2.0) 1.0 (0.8–2.0) 0.014 w2 1.0 (0.6–2.0) 1.0 (0.6–2.4) 0.020 Data are presented as mean ± standard deviation or median (interquartile range) unless otherwise stated
Abbreviations: APACHE II Acute physiology and chronic health evaluation II, CCI Charlson comorbidity index, MICU Medical intensive care unit, NIV Non-invasive ventilation, BUN Blood urea nitrogen, PaO2/FiO2ratio of the partial
pressure of arterial oxygen to the fraction of inspired oxygen, WBC White blood cell count, w1, Data collected within days 1–5 after ICU admission, w2 Data collected within days 8–12 after ICU admission
551 patients with MV ≥ 14 days were enrolled
508 patients were included for study
43 patients with tracheostomy at admission were
excluded 2,098 adult ICU admission
with invasive MV ≥ 24 hours were screened
344 patients receiving persistent translaryngeal intubation during hospitalization
164 patients undergoing tracheostomy during
hospitalization
Fig. 1 Flow diagram of the study population. Abbreviations: ICU Iintensive care unit, MV Mechanical ventilation
Table 2 Clinical outcomes of patients receiving mechanical ventilation for at least 14 days
Translaryngeal tube (n = 344) Tracheostomy (n = 164) p value Duration of MV, days 26 (21–35) 37 (25–51) <0.001 Weaning rate, n (%) 139 (40 %) 113 (69 %) <0.001 Transition to regional hospitals, n (%) 62 (18 %) 40 (24 %) 0.120 Time to transition, days 28 (21–40) 54 (44–80) <0.001 ICU length of stay, days 25 (20–33) 40 (25–55) <0.001 Hospital length of stay,
days
30 (22–45) 59 (45–94) <0.001 ICU mortality, n (%) 147 (43 %) 28 (17 %) <0.001 Hospital mortality, n (%) 186 (54 %) 36 (22 %) <0.001 Data are presented as median (interquartile range) unless otherwise stated Abbreviations: MV Mechanical ventilation, ICU Intensive care unit
independent factors significantly associated with in-hospital mortality included a DNR order, undergoing
NIV after extubation, malignancy and a PaO2/FiO2
ratio >282 (w2) (Table 3). The other factors inde-pendently associated with successful weaning included a DNR order, sepsis, chronic lung disease, APACHE II score >23, a PaO2/FiO2 ratio >282 (w2) and a
platelet count >140 × 103/μl (w2) (Table 3).
In view of the significant baseline heterogeneity be-tween the tracheostomy and translaryngeal intubation groups (see Table 1), we performed a case-matched com-parison using the propensity score-based algorithm. As shown in Table 4, except for pneumonia, no significant differences were found between the two groups concern-ing ICU admission or clinical characteristics in week 1 or week 2. Similar to the findings before matching, tracheostomized patients had significantly lower ICU and hospital mortality rates, a higher successful weaning rate, longer duration of MV, ICU and hospital stays, and later transition to regional hospitals (Table 4). In a sensi-tivity analysis to match the propensity score within 0.05, 139 cases for each group were matched, and the results were consistent with those described above.
Discussion
We found that patients requiring PMV (≥14 days) who did not undergo tracheostomy had significantly higher ICU and in-hospital mortality, and were less likely to be successfully weaned, after carefully controlling for poten-tial demographic and clinical confounders. Interestingly,
translaryngeal intubated patients had significantly
shorter durations of MV and ICU and hospital stays than patients who underwent a tracheostomy. To the best of our knowledge, this is the first report to have compared the short-term outcomes of patients who re-ceived MV for at least 14 days and either underwent
tracheostomy or remained intubated by the translaryn-geal route for a prolonged period.
We also found that the ICU type, a DNR order, under-going NIV after extubation, brain disorders and trauma as the cause of ICU admission, renal function, CCI score and comorbidities such as chronic heart, liver and con-nective tissue diseases were associated with the rate and timing of tracheostomy, findings that are consistent with a previous report [17]. Our finding that tracheostomy was independently associated with reduced ICU and in-hospital mortality rates is also consistent with some pre-vious reports [17, 18], but not others [19, 20]. Clec'h et al. [19] reported that tracheostomy had no positive influence on survival when performed in unselected mechanically ventilated patients. Their cohort included patients requiring MV for at least 2 days but nearly half received MV for <15 days, and therefore their findings may have been biased by the presence of a subgroup more likely to have been weaned from MV without the need for tracheostomy [9]. In contrast, our study in-cluded only those patients receiving MV for ≥14 days, a cohort in which failed extubation and severe comorbidi-ties were more common; a greater proportion would be expected to require long-term ventilatory support and would be more likely to benefit from tracheostomy [4]. Similarly, Trouillet and colleagues [20] compared pa-tients undergoing tracheostomy after 5 days of ventila-tory support with those intubated by the translaryngeal route for a prolonged period, and found that tracheos-tomy did not affect mortality; however, they included pa-tients ventilated after cardiac surgery who had failed weaning trials at day 4 of MV and 27 % of the patients in the prolonged translaryngeal intubation group eventu-ally underwent a tracheostomy.
In our study, the substantially reduced risk of death (aHR 0.26) in the tracheostomy group could in part be Table 3 Factors associated with in-hospital mortality and successful weaning in patients receiving mechanical ventilation for at least 14 days
Hospital mortality Successful weaning
aHR (95 % CI) p value aHR (95 % CI) p value
Performing tracheostomy 0.26 (0.18–0.39) <0.001 2.05 (1.56–2.68) <0.001 Do-not-resuscitate order 2.55 (1.92–3.38) <0.001 0.53 (0.39–0.72) <0.001 NIV after extubation 0.50 (0.35–0.71) <0.001
Malignancy 1.33 (1.01–1.75) 0.044
Sepsis 0.61 (0.47–0.80) <0.001
Chronic lung disease 0.68 (0.50–0.93) 0.016
APACHE II score > 23 0.71 (0.55–0.93) 0.012
PaO2/FiO2> 282 (w2) 0.73 (0.56–0.96) 0.023 1.34 (1.04–1.73) 0.023
Platelet > 140 × 103/μl (w2) 1.37 (1.05–1.79) 0.020
Abbreviations: aHR Adjusted hazard ratio, APACHE II Acute physiology and chronic health evaluation II, CI Confidence interval, NIV Noninvasive ventilation, OR Odds ratio, PaO2/FiO2Ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen, w2 Data collected within days 8–12 after ICU admission
explained by the fact that tracheostomy is associated with a decreased risk for VAP in patients requiring PMV [6]. In tracheostomized patients, tracheostomy allows the vocal cords to close, reduces aspiration of oropha-ryngeal secretions, reduces bacterial biofilm formation along the inside of the tracheotomy cannula and facili-tates weaning from MV. All these factors probably result in a reduced risk for VAP [6]. Another potential explan-ation is that ICU physicians may be adept at selecting candidates for tracheostomy based on the highest prob-ability of survival, and therefore may provide more ag-gressive treatment for these patients while being more likely to offer conservative or palliative treatment to those intubated by the translaryngeal route for a pro-longed period. In a retrospective study, it is also possible that we might have missed some important confounding factors associated with the decision to undertake trache-ostomy that might also affect outcomes, even when so-phisticated adjustment methods such as multivariable analyses or propensity score-based nested case–control studies are used.
Aside from tracheostomy, we identified a DNR order, NIV after extubation, malignancy and a PaO2/FiO2ratio
(w2) as the factors independently associated with in-hospital mortality in patients receiving MV for≥14 days. There is a body of evidence that using NIV after extuba-tion improves survival rate in high-risk patients [13–16]; NIV is commonly employed in our clinical practice to prevent post-extubation respiratory failure. Malignancy is recognized as a predictor of poor outcome in patients requiring PMV [3]. Increased PaO2/FiO2ratio in week 2
might simply reflect a favorable response to treatment, leading to better outcomes. Furthermore, we found that tracheostomy was associated with increased successful weaning rates. In contrast, Wu et al. [18] reported that tracheostomy has no effect on successful weaning. This Table 4 Case-matched study: demographic and clinical
characteristics of patients mechanically ventilated for at least 14 days Translaryngeal tube (n = 164) Tracheostomy (n = 164) p value Age, years 68 (54–77) 64 (51–74) 0.749 Male, n (%) 108 (66) 110 (67) 0.899 MICU, n (%) 87 (53) 94 (57) 0.464 APACHE II score 24.3 ± 7.4 23.2 ± 7.5 0.448 Do-not-resuscitate order 44 (27) 39 (24) 0.568 NIV after extubation, n (%) 26 (16) 24 (15) 0.871 Diagnosis of ICU admission, n (%)
Pneumonia 75 (46) 94 (57) 0.033 Sepsis 68 (42) 68 (42) 1.000 Cardiovascular or vascular disorder 13 (8) 12 (7) 1.000 Trauma 17 (10) 23 (14) 0.361 Brain disorder 70 (43) 76 (46) 0.571 Gastrointestinal disorder 42 (26) 51 (31) 0.328 CCI score 2 (1–3) 2 (0–3) 0.836 Comorbidities, n (%) Diabetes 55 (34) 66 (40) 0.235
Chronic lung disease 36 (22) 37 (23) 1.000 Chronic heart disease 30 (18) 29 (18) 1.000 Chronic liver disease 14 (9) 12 (7) 0.839 Chronic renal disease 35 (21) 30 (18) 0.575
Malignancy 44 (27) 44 (27) 1.000
Connective tissue disease 1 (1) 1 (1) 1.000 Neuromuscular disease 8 (5) 10 (6) 0.804 PaO2/FiO2 w1 302.1 ± 137.7 266.6 ± 132.0 0.899 w2 312.0 ± 101.9 293.6 ± 110.0 0.734 WBC (× 103/μl) w1 11.9 (9.0–14.4) 10.8 (8.4–15.9) 0.901 w2 10.7 (8.1–12.8) 11.5 (7.9–14.9) 0.449 Platelet (× 103/μl) w1 181.0 (122.0–226.0) 148.0 (102.5–195.3) 0.516 w2 183.3 ± 100.6 170.1 ± 99.2 0.978 BUN (mg/dl) w1 18.0 (13.0–35.0) 28.5 (14.3–49.8) 0.774 w2 38.0 (24.0–69.0) 44.0 (22.0–65.3) 0.706 Creatinine (mg/dl) w1 1.1 (0.8–2.5) 1.0 (0.8–2.0) 0.111 w2 1.3 (0.7–2.4) 1.0 (0.6–2.4) 0.327 Transition to regional hospitals, n (%)a 39 (24) 40 (24) 0.808 Time to transition, daysb 27 (21–45) 54 (44–80) 0.009 Duration of MV, daysb 28 (21–35) 37 (25–51) <0.001 Weaning rate, n (%)a 65 (40) 113 (69) <0.001
Table 4 Case-matched study: demographic and clinical characteristics of patients mechanically ventilated for at least 14 days (Continued)
ICU length of stay, daysb 27 (21–34) 40 (25–55) <0.001 Hospital length of stay,
daysb
30 (23–46) 59 (45–94) <0.001 ICU mortality, n (%)a 63 (38) 28 (17) <0.001 Hospital mortality, n (%)a 76 (46) 36 (22) <0.001 Data are presented as median (interquartile range) or mean ± standard deviation unless otherwise stated
a
Compared with general estimation equation analysis, adjusted for pneumonia
b
Compared with mixed-model analysis, adjusted for pneumonia Abbreviations: APACHE II Acute physiology and chronic health evaluation II, BUN Blood urea nitrogen, CCI Charlson comorbidity index, MICU Medical intensive care unit, MV Mechanical ventilation, NIV Noninvasive ventilation, ICU Intensive care unit, PaO2/FiO2Ratio of the partial pressure of arterial
oxygen to the fraction of inspired oxygen, WBC White blood cell count, w1 Data collected within days 1–5 after ICU admission, w2 Data collected within days 8–12 after ICU admission
discrepancy might be explained by a difference in study setting (ours was conducted in an ICU while theirs took place in a specialist respiratory care center). Moreover, tracheostomy has been reported to contribute to facilita-tion of weaning from MV by decreasing airflow resist-ance and the associated work of breathing, allowing clinicians to be more aggressive in their weaning strat-egies and reducing their concerns about sedation and reintubation [4]. In addition, we found that a DNR order, sepsis, chronic lung disease, APACHE II score, PaO2/
FiO2ratio (w2) and platelet count (w2) were
independ-ently associated with weaning success. These findings are similar to that of previous studies regarding the pre-diction of weaning or extubation failure [16]. Platelet count has also been reported to be associated with suc-cessful weaning in patients requiring PMV after cardiac surgery [21]. The relationship between existence of a current DNR order and poor outcomes can be explained by the presence of irreversible and terminal diseases.
There have been reports that early tracheostomy was not associated with a reduced length of ICU stay, hos-pital stay or duration of MV [9, 10]. Indeed, consistent with previous studies [17–19], we found that tracheos-tomy increased the duration of MV and length of ICU and hospital stays compared with translaryngeal intub-ation. These observations may be partially explained by the relatively long median time before tracheostomy (18 days) in the tracheostomy group. The shorter dur-ation of MV, and shorter length of ICU and hospital stays in the translaryngeal intubation group probably re-flect these patients’ higher mortality rate and earlier death (30 days compared with 61 days) or transition to lower-level regional hospitals.
Our study had some limitations. First, we did not rec-ord data regarding the effects of inadvertent extubation on the outcomes of the translaryngeal intubated group, tracheostomy complications, the incidence of extubation failure or the rate of VAP. All these factors may be asso-ciated with patient morbidity, mortality and successful weaning. We did not record serial ICU scores (such as the daily Sequential Organ Failure Assessment), which may have more accurately reflected the severity of illness at the time of tracheostomy (after a median of 18 days of MV) than the APACHE II score in the first 24 h of ICU admission [17]. Second, our study was undertaken retrospectively; this may have caused us to miss import-ant confounders relevimport-ant to the results, while accounting for the significant heterogeneity between the translaryn-geal intubation group and the tracheostomy group. Con-sequently, we cannot completely rule out the possibility that clinical practice on the ICU tends to select patients with the highest likelihood of survival for tracheostomy, although we matched for propensity scores, adjusted for potential confounders and performed a sensitivity
analysis in which even more stringent propensity score matching was employed that yielded the same results. Third, we did not assess the long-term outcomes after hospital discharge. Further study is needed to determine whether there are long-term benefits of tracheostomy on outcomes compared with translaryngeal intubation. A prospective, randomized controlled study will be needed to eliminate the biases described above.
Conclusions
Tracheostomy was independently associated with re-duced ICU and in-hospital mortality, and increased suc-cessful weaning rate, for critically ill patients requiring MV for at least 14 days. Tracheostomized patients had a longer duration of MV and length of ICU and hospital stays compared with patients who remained intubated by the translaryngeal route for a prolonged period. The cost-effectiveness and long-term outcomes of tracheos-tomy for critically ill patients requiring PMV require fur-ther study.
Key messages
For patients requiring MV for at least 14 days, tracheostomy was significantly associated with reduced ICU and hospital mortality and increased successful weaning rate. The results were consistent after matching for the propensity score of performing tracheostomy.
A time-dependent covariate Cox model showed that
tracheostomy was independently predictive of lower in-hospital mortality and higher successful weaning rate.
Our finding that tracheostomized patients required longer periods of MV, and longer ICU stay and hospitalization warrants further study to evaluate the cost-effectiveness and long-term outcomes of tracheostomy for critically ill patients requiring PMV.
Additional file
Additional file 1: Table S1. Definition of primary ICU admission diagnosis and comorbidities in our cohort. (PDF 60 kb)
Abbreviations
APACHE:Acute physiology and chronic health evaluation; BUN: blood urea nitrogen; CCI: Charlson comorbidity index; CI: confidence interval; HR: hazard ratio; ICU: intensive care unit; IQR: interquartile range; MV: mechanical ventilation; NIV: noninvasive ventilation; OR: odds ratio; PaO2/FiO2: ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen; PMV: prolonged mechanical ventilation; WBC: white blood cell.
Competing interests
Authors’ contributions
WCL participated in the study design, collected data, analyzed data and wrote the manuscript. CWC was responsible for data collection and analysis. JDW was responsible for study design, data analysis and manuscript revision. LMT was responsible for study design and manuscript revision. All authors read and approved the final manuscript.
Author details
1Department of Internal Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, No. 138 Sheng-Li Road, Tainan 704, Taiwan.2Department of Public Health, College of Medicine, National Cheng Kung University, No. 1 University Road, Tainan 701, Taiwan.
Received: 17 September 2015 Accepted: 2 December 2015
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