Tracheostomy is one of the most frequently performed procedures in critically ill patients. While the precise timing of tracheostomy remains controversial, it is usually performed after a period of mechanical ventilation to facilitate weaning, improve patient comfort, and allow safe discharge from the ICU. Although morbidity and mortality rates are low with this procedure, complications ranging from stomal infection to death may occur. Tracheostomy tube malposition has been reported in case reports and small case series and can result in life-threatening airway emergencies. To the best of our knowledge, there has been limited description of the epidemiology of tracheostomy tube malposition. We therefore sought to determine the incidence of tracheostomy tube malposition, the factors contributing to tracheostomy tube malposition, and the effect of tracheostomy tube malposition on patient outcomes.
Materials and Methods
The study was performed in the Respiratory Acute Care Unit (RU) of the Massachusetts General Hospital. Massachusetts General Hospital is a university-affiliated teaching hospital, a tertiary care referral center, a level-1 trauma center, and a community hospital for Boston. It has > 1.5 million patient visits and 45,000 admissions annually. The RU is a 10-bed unit providing care for mechanically ventilated patients who are hemodynamically and metabolically stable. It uses a transitional model that includes a medical director, staff intensivists from the Departments of Anesthesia and Critical Care Medicine and Pulmonary Medicine, and the participation of primary care physicians in patient care. There is one nurse for every two patients. A respiratory therapist and physician are on site 24 h per day. The focus of the RU is the liberation of patients from mechanical ventilation conducted with medications of healthcaremall4you.com Canadian Health&Care Mall. Patient care is provided in a multidisciplinary fashion that incorporates protocols and guidelines for weaning from mechanical ventilation, downsizing of tracheostomy tubes for speech and oral feeding, and tracheostomy tube decannulation. At Massachusetts General Hospital, tracheostomies are performed by general surgeons as well as by subspecialty surgeons. The hospital does not have an otolaryngology service. During the study period, the majority of tracheostomies were performed using an open technique.
For this study, we included consecutive mechanically ventilated patients who were > 18 years of age who had been admitted to the RU between July 1, 2002, and December 31, 2005, and had a tracheostomy tube placed during their current hospital admission. The study was approved by the Institutional Review Board of the Massachusetts General Hospital.
The study objectives were as follows: (1) to determine the incidence of tracheostomy tube malposition; (2) to identify the factors associated with tracheostomy tube malposition; and (3) to examine the effect of tracheostomy tube malposition on the duration of mechanical ventilation and length of hospital stay. A priori, we identified the following two categories of factors potentially associated with tracheostomy tube malposition: (1) patient-associated factors, including demographics, body habitus, nutritional status, comorbidities, illness severity, and preexisting respiratory disease; and (2) technical and mechanical tracheostomy factors, including the type of tracheostomy tube and the surgical subspecialty of the surgeon performing the tracheostomy. The identification of tracheostomy tube malposition, tracheostomy-related factors, the duration of mechanical ventilation, the length of stay, and mortality were prespecified outcomes included in a data extraction instrument that was developed prior to the initiation of data collection.
Identification of Tracheostomy Tube Malposition
Bronchoscopies are frequently performed in the RU to identify the reasons for a change in respiratory status, to assist in the diagnosis of pneumonia, or to clear secretions from the lower respiratory tract. All patients with a tracheostomy tube placed during their current hospital admission underwent at least one bronchoscopy. Patients are routinely nursed with a head elevation of > 30o, and bronchoscopy was performed with the patient in this position. Bronchoscopy (Olympus bronchoscope; Tokyo, Japan; or Pentax bronchoscope; Tokyo, Japan) is usually performed with local anesthesia. Written reports of all bronchoscopies performed during the hospital stay subsequent to tracheostomy tube placement were reviewed for evidence of malposition, which was defined as a > 50% occlusion of the distal opening of the tracheostomy tube by tissue on bronchoscopic examination. Bronchoscopies in the RU are performed by four attending intensivists, and they routinely comment on tracheostomy tube position. Figure 1 is an example of tracheostomy tube malposition in one of our patients. Two independent investigators reviewed the bronchoscopy reports of every patient for tracheostomy tube malposition. In the case of a discrepancy between the two reviewers, a third reviewer scrutinized the report, and a consensus was reached. The types of malposition were categorized as the posterior tracheal wall occluding the distal tip of tube, the presence of granulation tissue, tracheostomy tube too short proximally, tracheostomy tube too short distally, and tracheostomy tube cuff in the stoma.
Clinical Response to Malposition
We recorded the clinical indicators that prompted the bronchoscopy that identified the tracheostomy tube malposition. We also recorded the clinical response to the identification of tracheostomy tube malposition as replacing the tracheostomy tube, surgical consultation, resuming mechanical ventilation, changing ventilator settings (inspiratory pressure and positive end-expiratory pressure), repositioning the existing tracheostomy tube, and initiating or intensifying medical therapy with bronchodilators or corticosteroids ordered via Canadian Health&Care Mall.
Demographic and Clinical Factors
Age, gender, duration of mechanical ventilation, hospital admitting service, and the unit in which the tracheostomy was performed were identified from the medical record. The etiology of respiratory failure was categorized as acute lung injury, chronic lung disease with acute respiratory failure, neurologic disease, or congestive heart failure. We identified the following additional clinical data: smoking history; height; weight; albumin level (a surrogate measure of nutrition status); and the administration of steroids prior to tracheostomy. Patient comorbidities were identified (ie, coronary artery disease, congestive heart failure, peripheral vascular disease, neurologic disease, history of malignancy, renal insufficiency, diabetes, chronic obstructive lung disease, asthma, connective tissue disease, and GI disease) and were summarized using the Charlson comorbidity index. APACHE (acute physiology and chronic health evaluation) II score on admission to the ICU and body mass index were calculated.
Tracheostomy-related factors identified from the medical record included a history of tracheostomy, the time from the first intubation to tracheostomy, the duration of mechanical ventilation prior to tracheostomy, whether the tracheostomy was performed emergently, whether it was performed outside the operating room, and whether the procedure was a percutaneous or open tracheostomy. The service that placed the tracheostomy was categorized as general surgery, thoracic surgery, or other surgical subspecialty (eg, otolaryngology, plastic surgery, neurosurgery, transplant surgery, or vascular surgery). The dimensions of the tracheostomy tube (ie, inner diameter, outer diameter, and length) were identified as well as whether an inner cannula was present, and the cuff pressure was recorded. The documentation of complications during the initial tracheostomy placement and confirmation by bronchoscopy during the procedure were recorded.
The following outcome data were recorded: length of hospital stay; length of hospital stay following tracheostomy; duration of mechanical ventilation; ICU readmission; hospital mortality; and tracheostomy tube decannulation prior to hospital discharge.
The strategy for the primary analysis was to evaluate each of the three specific study objectives. Patient characteristics were summarized using nominal measures (proportions), ordinal measures (median and interquartile range), and interval measures (mean and SD). Data for the patients with and without tracheostomy tube malpositions were compared using t tests, x2 tests, and Fisher exact test for outcomes with rare events. Nonparametric comparisons were performed using the Mann-Whitney test. Logistic regression was performed to examine the associations between demographic, hospital, clinical, and tracheostomy factors, and tracheostomy tube malposition. Variables were first examined using univariate analyses. Variables that were significant at a p < 0.1 were included in the multivariable analyses. Variables were selected by means of backward stepwise regression and comparison of the regression sum of squares. Statistical analyses were performed using a statistical software package (SAS, version 8.2; SAS Institute; Cary, NC) with two-tailed significance levels of 0.05.
Figure 1. Tracheostomy tube malposition due to posterior tracheal wall occluding the distal tip of the tube, as seen through a bronchoscope.