Prognostic indicators for early mortality after tracheostomy in the intensive care unit

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Prognostic indicators for early mortality after tracheostomy in the intensive care unit Afshin Parsikia, MD, MPH,a Matthew Goodwin, MD,b Zachary Wells, BS,c Zoe Gauthier, BS,c Molli Bascom, BS,c Moon Suh, BS,c Beth Meloro, BS,c Jorge Ortiz, MD,b and Amit R.T. Joshi, MD, FACSa,* a

Department of Surgery, Einstein Healthcare Network, Philadelphia, Pennsylvania Department of Surgery, University of Toledo Medical Center, Toledo, Ohio c Philadelphia College of Osteopathic Medicine, Philadelphia, Pennsylvania b

article info

abstract

Article history:

Background: Tracheostomy is indicated for patients requiring prolonged mechanical

Received 8 January 2016

ventilation. The aim of this study is to identify prognostic indicators for early mortality

Received in revised form

after tracheostomy to potentially avoid futility in the intensive care unit.

28 June 2016

Methods: Patients who underwent tracheostomy and died within 30 d of admission (futile

Accepted 2 August 2016

group) were compared with patients who underwent tracheostomy and survived more

Available online 9 August 2016

than 30 d after admission (nonfutile group). Categorical data were analyzed using chisquare and Fisher’s exact tests. Continuous variables were analyzed using T-tests and

Keywords:

ManneWhitney U tests. Prognostic factors were evaluated with univariable and multi-

Tracheostomy

variable logistic regression analyses.

Hypoalbuminemia

Results: Overall, 88.3% of patients underwent nonfutile tracheostomy, while 11.7% under-

Futility

went futile tracheostomy. Serum albumin level (1.5 g/dL versus 1.9 g/dL, P ¼ 0.040) and

Critically ill

mechanical ventilation duration before procedure (10 versus 12 d, P ¼ 0.029) were significantly less in the futile group. Hypoalbuminemia (<2 g/dL) and preoperative mechanical ventilation 10 d were also predictive of futile tracheostomy in multivariable analysis. Conclusions: Hypoalbuminemia may serve as a prognostic indicator and risk factor for early mortality after tracheostomy. In patients with hypoalbuminemia, treatment of underlying disease processes and trending serum albumin level recovery in response to treatment may provide some insight to clinicians with regard to timing of tracheostomy. Better prognostic tools are still needed for critically ill patients to avoid futility in the intensive care unit. In this cohort, 88.3% of patients undergoing tracheostomy survived past 30 d. ª 2016 Elsevier Inc. All rights reserved.

Introduction Tracheostomy is indicated for patients requiring prolonged mechanical ventilation. It offers greater patient comfort,

decreased sedative and antipsychotic use, increased airway security, lower prevalence of unplanned extubation, and easier patient mobility.1,2 In addition, early tracheostomy has been shown in select patient groups to decrease intensive care

This manuscript was presented as an oral presentation at the 11th Annual Academic Surgical Congress on February 2, 2016 in Jacksonville, Florida. * Corresponding author. Department of Surgery, Einstein Healthcare Network, Jefferson Medical College, Philadelphia, PA. Tel.: þ1 215 456 6783; fax: þ1 215 722 3893. E-mail address: [email protected] (A.R.T. Joshi). 0022-4804/$ e see front matter ª 2016 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jss.2016.08.003

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unit (ICU) length of stay (LOS) and duration of mechanical ventilation.3 However, randomized control studies and metaanalyses comparing early and late tracheostomy have shown that timing does not affect mortality or overall hospital outcome.2,4-6 Although the incidence of tracheostomy in critically ill patients continues to increase, it is not without risks. Loss of airway, bleeding, and infection comprise early complications.7 Excess granulation tissue with tracheal stenosis, tracheomalacia, tracheoarterial fistula, and persistent stoma can be seen in the late period.7 Tracheostomy is associated with a major complication rate of 4.3% and mortality rate of 0.7%.8 The purpose of this study is to identify prognostic indicators of early mortality in patients who underwent tracheostomy to avoid the performance of futile procedures.

Methods Our institutional review board reviewed this retrospective study of 500 consecutive critically ill patients who underwent tracheostomy, and determined that it was exempt from review and the need for patient consent. All patients had tracheostomies performed for respiratory failure at a single, tertiary care center between August 20, 2009 and October 12, 2013. Inclusion criteria consisted of adult patients at least 18 years of age with respiratory failure requiring mechanical ventilation. Patients with missing operative data, presentation from an outside facility, history of prior tracheostomy, tracheostomy procedures for oral cavity or upper airway malignancy, and emergent cricothyroidotomy or ambulatory procedures were excluded from the analysis. Patients who underwent tracheostomy and died within 30 d of admission were identified and labeled as having undergone futile procedures (futile group [FG]). These patients were compared to patients who underwent tracheostomy and survived more than 30 d after admission (nonfutile group [NFG]). Days were defined based on a 24-h period with a new day beginning after midnight. We collected specific demographic and clinical variables, as well as other characteristics regarding each patient’s course, including: age, gender, preoperative laboratory data; length of ICU stay; length of hospital stay; body mass index; type of procedure; disposition on discharge; reoperation due to tracheostomy complications; medical ICU (MICU) admission versus surgical ICU (SICU) admission; otorhinolaryngology versus surgery performance of tracheostomy; history of trauma; positive end-expiratory pressure 10 cm H2O; and history of cervical spine injury. Categorical data were analyzed using chi-square and Fisher’s exact tests. Continuous variables were analyzed using T-tests and ManneWhitney U tests. Prognostic factors for futility were evaluated with univariable and multivariable logistic regression analyses. Based on the differences that we found between the two groups (Table 1), we selected preoperative serum albumin, age, preoperative serum creatinine, and duration of mechanical ventilation before tracheostomy for logistic regression analysis. An analysis of “days on mechanical ventilation” before tracheostomy revealed that the mode was 10 d, and the mean was 12.2 (5.9) d (Fig. 1). Distribution of days on mechanical ventilation between the

two groups is demonstrated in box plots (Fig. 2). There were 12 patients with 0 d of mechanical ventilation before tracheostomy. Five of these 12 patients underwent tracheostomy on the same day of admission, and 7 of the 12 underwent tracheostomy between 4 and 14 d after admission. Based on these findings, we incorporated a cutoff of 10 d for the duration of mechanical ventilation before tracheostomy and included it as a separate variable in the logistic regression tests to evaluate prognostic factors for futile tracheostomy. Similarly, we defined benchmarks of 60 years for age, 2 g/dL for preoperative serum albumin, and 1.3 mg/dL (which is abnormal in our laboratory) for preoperative serum creatinine (Tables 2 and 3). The statistical significance for the difference of creatinine between the two groups was marginal (P value ¼ 0.051). As such, although nonsignificant, we included the preoperative serum creatinine with the defined benchmark in our logistic regression. The calibration of the final model was tested with a HosmereLemeshow test.

Results Retrospective review identified 500 consecutive patients who underwent tracheostomy at a tertiary care ICU during the study period, of which 82 were excluded. About 369 of 418 (88%) survived beyond 30 d after admission and were placed in the NFG. Overall, 49 of 418 (12%) patients died within 30 d of admission and were therefore placed in the FG. Twenty-five of these patients (51%) were identified as “do not resuscitate” or withdrawal of care and/or comfort care status at some point in their hospitalization. Comparative analysis of these cohorts is described in the following paragraphs and presented in Table 1. The two groups were well matched with regard to basic demographics. There were no significant differences in age, gender, or weight. In addition, no difference was detected in ICU setting (MICU versus SICU) between the cohorts. Etiologies such as cervical spine injury or trauma were compared between cohorts with no difference. Overall, the two cohorts underwent similar procedural techniques. Percutaneous tracheostomy was performed more frequently than open tracheostomy with no statistical difference (57.2% versus 42.8%, P ¼ 0.217). In the SICU, percutaneous tracheostomy was performed in 152 of 182 (83.5%). Whereas in the MICU, percutaneous tracheostomy was performed in 87 of 236 (36.9%). There was no statistically significant difference in futility based on technique (Table 4). Significant differences in duration of mechanical ventilation, ICU, and hospital LOS, serum albumin level, discharge disposition, and mortality were identified between the cohorts. The median duration of mechanical ventilation before tracheostomy was 10 d for the FG (range, 0-21 d) compared with 12 d for the NFG (range, 0-42 d). This difference was statistically significant (P ¼ 0.029). Mechanical ventilation days before tracheostomy in the entire cohort was 12 d (range, 0-42 d). Positive end-expiratory pressure 10 cm H2O was observed in 40 of 418 (9.6%) of patientsdno difference was seen between FG and NFG. The median ICU LOS was 19 d (range, 0-29) in the FG compared with 25 d (range, 3-130) in the NFG (P < 0.0001). The

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parsikia et al  prognosis after tracheostomy

Table 1 e Patient characteristics in the FG and NFG. FG (n ¼ 49)

NFG (n ¼ 369)

Overall (n ¼ 418)

P value

Length of ICU stay (d)

19 (0-29)

25 (3-130)

24 (0-130)

<0.0001

Duration of mechanical ventilation before tracheostomy* (d)

10 (0-21)

12 (0-42)

12 (0-42)

0.029

Variable *

*

2

BMI (kg/m )

27 (14-159)

27.12 (14-159)

0.305

INR*

28.15 (18-70) 1.2 (0.8-2.6)

1.2 (0.9-2.9)

1.2 (0.8-2.9)

0.043

Albumin* (g/dL)

1.5 (0.6-3.7)

1.9 (0.7-4.5)

Total bilirubin* (mg/dL)

0.6 (0.2-4)

0.6 (0.1-21)

0.60 (0.1-21)

Creatinine* (mg/dL)

1.20 (0.4-8)

0.9 (0.2-12)

0.90 (0.2-12)

0.051

Length of stay* (d)

19.5 (1-29)

32 (5-218)

29 (1-218)

<0.0001

Agey (y)

63.8 (17.3)

60.2 (16.2)

60.6 (16.4)

0.151

3 (6.1%)

21 (5.7%)

24 (5.7%)

0.752

Otorhinolaryngology-performed tracheostomyz

1.8 (0.60-4.50)

ICU settingz

0.306

Medical

31 (63.3%)

205 (55.6%)

236 (56.5%)

Surgical

18 (36.7%)

164 (44.4%)

182 (43.5%)

Open tracheostomy

25 (51%)

154 (41.7%)

179 (42.8%)

Percutaneous tracheostomy

24 (49%)

215 (58.3%)

239 (57.2%)

Procedure typez

Disposition

0.040 0.903

0.217

z

Expired in hospital Home Hospice SNF

34 (9.2%)

79 (18.9%)

<0.0001

0

8 (2.2%)

8 (1.9%)

0.604

1 (2%)

19 (5.1%)

20 (4.8%)

0.492

308 (83.5%)

311 (74.6%)

<0.0001

6 (1.6%)

7 (1.7%)

0.585

45 (91.8%)

3 (6.1%)

Reoperationz

1 (2%)

Cervical spine injuryz

5 (10.2%)

28 (7.6%)

33 (7.9%)

0.570

PEEP 10z

8 (16.3%)

32 (8.7%)

40 (9.6%)

0.115

Traumaz

8 (16.3%)

83 (22.5%)

91 (21.8%)

0.326

201 (54.5%)

225 (53.8%)

0.469

Gender, male

z

24 (49%)

BMI ¼ body mass index; FG ¼ futile group; ICU ¼ intensive care unit; INR ¼ international normalized ratio; NFG ¼ nonfutile group; PEEP ¼ positive end-expiratory pressure; SNP ¼ skilled nursing facility. * Median for skewed variables, (range). y Mean for the variables in normal distribution, (SD). z Number, (%).

overall ICU LOS was 24 d (range, 0-130). The FG group had a significantly shorter hospital LOS compared with the NFG, 19.5 d (range, 1-29 d) versus 32 d (range, 5-218 d), respectively (P < 0.0001). The overall hospital LOS in the study population was 29 d (range, 1-218 d). Patients had four possible discharge dispositions including home, hospice, skilled nursing facility (SNF), and death in the hospital. Nearly 45 of 49 (91.8%) in the FG died in the hospital versus 34 of 369 (9.2%) for the NFG (P < 0.0001). Three of 49 (6.1%) in the FG were discharged to an SNF versus 308 of 369 (83.5%) in the NFG (P < 0.0001). Laboratory data were compared between the two cohorts. There were no significant differences in laboratory values between the FG and NFG groups with the exception of serum albumin level. The median preoperative albumin level for the FG was 1.5 g/dL (range, 0.6-3.7 g/dL) compared with 1.9 g/dL (range, 0.7-4.5 g/dL) in the NFG (P value ¼ 0.040). The overall preoperative albumin level for the entire group was 1.8 g/dL (range, 0.6-4.5 g/dL). In the univariable logistic regression, preoperative serum albumin level (odds ratio [OR], 0.249; 95% CI, [0.091, 0.681];

P ¼ 0.007) and mechanical ventilator days before procedure (OR, 1.853; 95% CI, [1.017, 3.378]; P ¼ 0.044) were statistically significant (Table 2). The overall cohort’s albumin was 1.8 g/ dL. A 2.0 g/dL was used as a cutoff for the purposes of regression analysis. The logistic regression models were not adjusted. Preoperative mechanical ventilation 10 d (OR, 3.146; 95% CI, [1.072, 9.227]; P ¼ 0.037) and preoperative albumin 2 mg/dL (OR, 0.159; 95% CI, [0.055, 0.462]; P ¼ 0.001) remained significant and prognostic (Table 3).

Discussion Respiratory insufficiency and failure are leading causes of ICU admission in the United States.9 Tracheostomy is indicated for patients requiring prolonged mechanical ventilation. The number of tracheostomy procedures continues to increase in parallel with ICU admissions. In fact, up to one-third of patients requiring prolonged mechanical ventilation undergo tracheostomy placement.10,11 The number has increased with

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Table 2 e Univariable logistic regression. Variable

Fig. 1 e Histogram showing mechanical ventilation days before tracheostomy.

the advent and feasibility of the bedside, percutaneous tracheostomy technique.12 Despite the increase in tracheostomies performed, outcomes for patients requiring prolonged mechanical ventilation remain poor.13 Cox et al.13 reported that only 9% of critically ill patients who experienced prolonged mechanical ventilation were alive and functionally independent at 1 y. Furthermore, considerable discordance exists between the information conveyed by physicians to surrogates of the critically ill and surrogates’ understanding of outcomes.13 It follows that a percentage of tracheostomies may be performed in the setting of poor outcomes and be viewed as futile. By comparing patients who died within 30 d of admission and underwent tracheostomies to those who survived longer than 30 d, the aim of this study was to identify prognostic indicators for early mortality after tracheostomy to avoid futile procedures. Some valuable information can be gleaned from our overall results, when counseling patients and their families about prognosis. Tracheostomy was the most commonly performed between 10 and 12 d of ventilator-dependent respiratory failure. Overall, 88.3% of patient undergoing tracheostomy survived past 30 d and were overwhelmingly discharged to an

Odds ratio

95% CI

P value

Aged 60 y

1.050

0.573-1.925

0.874

Preoperative serum albumin 2 g/dL

0.249

0.091-0.681

0.007

Preoperative serum creatinine 1.3 mg/dL

1.422

0.776-2.606

0.255

Mechanical ventilation 10 d

1.853

1.017-3.378

0.044

SNF. Of the 11.7% of patients who did not survive past 30 d, 91.8% died in this hospital. Only 1.9% of patients were discharged to home. The patients in this study were representative of MICU and SICU patients. A little over half of the patients who underwent tracheostomy were treated in the MICU (56.5%, Table 1). A higher percentage of patients in the FG were MICU patients compared with SICU patients (31 of 49, 63.3% MICU in FG), which is likely indicative of the different etiologies of MICU and SICU admissions. Patients in the FG underwent procedures significantly earlier than their NFG counterparts (10 versus 12 d, P value ¼ 0.029, Table 1). This was not a trial to evaluate “early” versus “late” tracheostomy per se. There is a possibility that clinicians were influenced by reports in the literature espousing the benefits of early tracheostomy.3-7 This underscores the fact that timing of tracheostomy is only one factor in a complex milieu of prognosticators which have not been entirely elucidated. Although the best practice procedures and guidelines were most likely adhered to, it is clear that physician assessment and severity of illness measures may inaccurately predict prognosis and underestimate poor outcomes in the ICU.13,14 Percutaneous tracheostomy was performed more frequently than open tracheostomy with no significant difference (57.2% versus 42.8%, P value ¼ 0.217, Table 1). In addition, no mortality difference was seen between the two techniques as patients in the FG were split almost evenly between open and percutaneous techniques (51% versus 49%). This is consistent with the current literature, which shows percutaneous tracheostomy to be safe, faster, and cost-sparing when compared with open techniques.15-18 Patients in the FG had significantly shorter ICU LOS and hospital LOS in the study. A plausible explanation is that patients in the FG had shorter ICU and hospital stays because the majority did not survive to discharge. Indeed, when analyzing discharge disposition, 91.8% of patients in the FG died in the hospital compared with 9.2% in the NFG (Table 1). Further

Table 3 e Multivariable logistic regression. Variable

Fig. 2 e Distribution of days on mechanical ventilation.

Odds ratio

95% CI

P value

Preoperative serum albumin 2 g/dL

0.159

0.055-0.462

0.001

Mechanical ventilation 10 d

3.146

1.072-9.227

0.037

parsikia et al  prognosis after tracheostomy

Table 4 e Distribution of percutaneous tracheostomy. SICU FG (n ¼ 18) 14 (77.8%)

NFG (n ¼ 164)

Overall (n ¼ 182)

P value

138 (84.1%)

152 (83.5%)

0.505

NFG (n ¼ 205)

Overall (236)

P value

77 (37.6%)

87 (36.9%)

0.568

MICU FG (n ¼ 31) 10 (32.3%)

FG ¼ futile group; MICU ¼ medical intensive care unit; NFG ¼ nonfutile group; SICU ¼ surgical intensive care unit.

examination of cause of death is needed to better gauge futility in this study as 51% of patients in the FG were made do not resuscitate or comfort care during the hospitalization. Patients in the FG had significantly lower median preoperative serum albumin levels before tracheostomy placement (1.5 mg/dL versus 1.9 mg/dL, P value ¼ 0.040, Table 1). Albumin is a negative acute phase protein in critical illness; therefore, serum levels decrease in the setting of severe illness or inflammation.19,20 Furthermore, serum albumin levels carry important prognostic value. Hypoalbuminemia is associated with increased length of stay, higher complication rates, and higher mortality in hospitalized patients.21 Trending albumin levels may be of value in the critically ill as a marker of recovery.22 Nonsurvivors of critical illness have prolonged hypoalbuminemia and a slower rate of albumin normalization compared to survivors.22,23 Ching et al.24 showed that survivors of critical illness were able to increase serum albumin levels with optimal nutritional support compared with nonsurvivors. However, there is no overwhelming evidence to suggest that albumin infusion is associated with better outcomes. Multiple randomized trials and meta-analyses have examined albumin infusion for resuscitation and supplementation in critically ill patients with no significant mortality benefit.25-28 In this study, lower preoperative serum albumin levels were indicative of poorer outcomes and early mortality, and possibly futility, after tracheostomy. It remains difficult to predict which patients requiring prolonged mechanical ventilation benefit most from tracheostomy placement. In our population, baseline demographics and laboratory data between the FG and NFG were similar, with the exception of preoperative serum albumin level and the duration of mechanical ventilation before tracheostomy. Hypoalbuminemia was a marker of early mortality after tracheostomy in this patient population. Logistic regression analysis showed that preoperative serum albumin 2.0 mg/dL was predictive of a nonfutile tracheostomy. In addition, preoperative mechanical ventilation 10 d was predictive of futile tracheostomy. This is an interesting finding and may reflect the fact that in our cohort, sicker patients (best represented by a significantly lower preoperative serum albumin) tended to be in the earlier tracheostomy group. This could have resulted from clinicians’ identifying those early patients as being sicker, and less likely to wean from mechanical ventilation, and therefore more likely to benefit from tracheostomy.

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Our analysis suggests that better prognostic tools are still needed for critically ill patients to avoid futility in the ICU. This begins with improved communication and clear expectations among caregivers, patients, and surrogates in the ICU as early as possible in a patient’s ICU admission. Cox et al.13 demonstrated that 1-y outcomes for patients requiring prolonged mechanical ventilation were significantly worse than expected by physicians and patients’ surrogates. They concluded that modifications in surrogate-physician interactions may improve the discordance between outcomes and expectations.13 In addition, improved prognostication may aid in avoiding futility in the ICU. A variety of prognostic tools and scoring systems are available and validated for use in the ICU.29-33 Severity scoring systems can aid physicians in determining risk of death or in clinical assessment.34 However, these tools should be part of the decision-making algorithm for physicians but not the sole determinant in individualizing patient care.34 Recently, Johnson et al.35 used a modified frailty index to identify patients at high risk of postoperative mortality after tracheostomy. Although not yet validated, the modified frailty index in this study exemplifies the use of a severity score to promote increased surrogatephysician communication and limit futility.35 In our institution, recommendations for tracheostomy are a consensus opinion generated from critical care intensivists, consultants, and palliative care specialists. Our study has several limitations. The data were collected retrospectively, which excludes insight into the decision-making process regarding tracheostomy placement in these patients. Determining futility is difficult without knowledge of physician, patient, and surrogate expectations, and the information that was exchanged among these parties. The retrospective design of this study limits our ability to determine the timing of events leading to withdrawal of treatment. Anticipated and unanticipated death was not elucidated in our study and would aid in determining potentially inappropriate care. Serial serum albumin levels were not trended in this study, which may have been useful to further stratify patients at risk of mortality. Furthermore, we were unable to tabulate other clinical parameters such as the use of vasopressors, the presence of diabetes mellitus, Glasgow Coma Scale or Acute Physiologic Assessment and Chronic Health Evaluation (APACHE) II Scoring System, serum lactate levels, the presence of concomitant infection, arterial oxygen levels, and other nutritional parameters, which are all markers for severity of patient illness. Finally, we chose arbitrary cutoffs for creatinine, albumin, age, and days on mechanical ventilation before tracheostomy for the purpose of statistical analysis. While these cutoffs were based on the characteristics of our cohort, they may have been responsible for some unintended bias. Futility, or potentially inappropriate medical treatment, remains difficult to define, has no set time parameters, and often includes a degree of subjectivity.36,37 Our selection of 30 d to differentiate our cohorts was modeled on many administrative and outcome databases (such as those used in cardiac surgery and Medicare readmission rates) that use 30-d benchmarks for definition of procedure-related outcomes.

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Conclusions Identifying patients at risk for early mortality after tracheostomy remains difficult, as baseline demographics, ventilator requirements, and laboratory data may be similar as in this study. Patients being considered for tracheostomy are, by definition, ill and suffer from a heterogeneous variety of etiologies, which adds confounding variables to any analysis. When counseling patients’ families about the risks and benefits of tracheostomy, it is important to emphasize that 88% of patients survive past 30 d. When trying to predict which patients may fall into the 12% of patients who do not survive 30 d, hypoalbuminemia may serve as a prognostic indicator and risk factor for early mortality after tracheostomy.

Acknowledgment Authors’ contributions: A.P., J.O., and A.R.T.J. conceived of and designed the study, acquisition, analysis, and interpretation of data, drafting and revision of the article. M.G. helped in interpretation of data and drafting and revision of the article. Z.W., Z.G., M.B., B.M., and M.S. carried out acquisition of data. A.R.T.J. carried out final approval of the article. There was no source of funding for this manuscript.

Disclosure All authors have read and agree to the content within the manuscript. None of the authors have any financial conflicts of interest or disclosures to make. There are no relevant financial relationships with companies or other entities. The manuscript has neither been submitted nor published elsewhere.

references

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