The Impact of Obesity on Adult Tracheostomy Complication Rate

The Laryngoscope VC 2014 The American Laryngological, Rhinological and Otological Society, Inc. TRIOLOGICAL SOCIETY CANDIDATE THESIS The Impact of Obesity on Adult Tracheostomy Complication Rate Susan R. Cordes, MD; Amy R. Best, MD; Kelly K. Hiatt, MD Objectives/Hypothesis: Prospectively compare tracheostomy-related complications in obese patients with complications in nonobese patients. Study Design: Prospective cohort study. Methods: Adult patients undergoing tracheostomy were studied. Patients who had a prior tracheostomy were excluded. Complications were classified as intraoperative, early (within the first 2 weeks), or late. Results: A total of 151 patients met inclusion/exclusion criteria. Fifty-five percent of obese patients experienced at least one tracheostomy-related complication; 19.5% of the control group had a complication. Mean procedure duration for patients with body mass index <30 was 24.74 minutes and for obese patients was 46.17 minutes. There was a statistically significant effect of body mass index on complication rate (P <.0001) and on procedure duration (P <.0001). The relationships between body mass index and intraoperative complications (P 5.027) and early postoperative complications (P 5.001) were significant. Conclusions: The tracheostomy-related complication rate is significantly higher for obese patients, especially for body mass index 35, especially in the intraoperative and early postoperative time periods. Procedure duration is significantly longer in obese patients. Key Words: Tracheostomy, obesity, complications. Level of Evidence: 2b. Laryngoscope, 125:105 110, 2015 INTRODUCTION Tracheostomy is a commonly performed procedure in the management of critically ill patients, and with the current rate of obesity (33.8% of adults 1 ), many tracheostomies are performed on obese patients. Although the tracheostomy complication rate in the present era is quite low, and most complications are minor, there remains the potential for life-threatening events. Given the difficult airway anatomy and other medical and anatomic concerns in obese patients, we hypothesized that there is a greater tracheostomy-related complication rate in this population. Darrat and Yaremchuk 2 retrospectively reviewed 278 patients undergoing tracheostomy and found a trend toward increased mortality rate after tracheostomy in obese patients; however, tracheostomy-related complications or mortality were not specifically analyzed in this study. In a retrospective study of 89 morbidly obese patients and 49 controls, El Solh and Jaafar 3 compared early complication From the Department of Otolaryngology/Head and Neck Surgery, Indiana University School of Medicine, Indianapolis, Indiana, U.S.A. Editor s Note: This Manuscript was accepted for publication May 27, 2014. Accepted at the Triological Society Combined Sections Meeting, Miami, Florida, U.S.A., January 12, 2014. The authors have no funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Susan Cordes, MD, Department of Otolaryngology/Head and Neck Surgery, Indiana University School of Medicine, 705 Riley Hospital Drive, #0860, Indianapolis, IN 46220. E-mail: sslakes@iupui.edu DOI: 10.1002/lary.24793 rates and determined that body mass index (BMI) was independently associated with increased risk of tracheostomyrelated complications. The incidence of long-term tracheostomy-related complications in obese patients is not reported. The purpose of this study was to prospectively: 1) document the types and timing of complications and 2) compare the intraoperative, early (within the first 2 weeks), and late tracheostomy-related complication rate of obese patients with that of nonobese patients. MATERIALS AND METHODS Study Population Approval was obtained from the institutional review board for a prospective cohort study of patients undergoing tracheostomy between November 2006 and January 2011. The hospital is a 255-bed, urban, level I trauma center with a regional burn center and medical, surgical, and coronary critical care units. Inclusion criteria were all adult patients (>18 years) undergoing tracheostomy by the otolaryngology service. Patients were excluded if they had a history of previous tracheostomy. Surgical Procedure All procedures were standard (not percutaneous dilational) tracheostomies and were performed by an attending otolaryngologist and a resident otolaryngologist. The decision regarding location of the procedure (operating room or intensive care unit bedside) was made by the attending surgeon on a case-by-case basis, taking into account all patient factors, including medical comorbidities, anatomic factors, and need for additional procedures. In most cases, a Bjork flap was created; however, in some obese patients, the skin to trachea distance was too great 105

TABLE I. National Institutes of Health Obesity Classification. 4 BMI, kg/m 2 TABLE II. Patient Demographics. BMI <30 BMI 30 Underweight <18.5 Normal 18.5 24.9 Overweight 25.0 29.9 Obesity class I 30.0 34.9 II 35 39.9 III 40 to allow this. For this study, procedure duration was defined as time from skin incision until placement of tracheostomy ties. The first tracheostomy tube change occurred postoperatively between days 3 and 10 by a member of the operative team. Data Data collected included demographic, procedure duration, elective versus emergent, procedure location, additional procedures performed, and tracheostomy-related complications. BMI was calculated using the imperial BMI formula, BMI 5 (weight in pounds 3 703)/(height in inches 2 ). Complications were classified as intraoperative, early postoperative (within the first 14 days), or late (>14 days postprocedure). Patients were followed for 12 months post-tracheostomy. Statistical Analysis Univariate analyses of variance (ANOVA) was used to look for effects of age or ethnicity on BMI. No statistically significant effects were found, so the data were collapsed across these variables in all remaining analyses. We compared the overweight group (BMI 25 29.9) to the BMI <25 group and found no difference in complication rate or procedure duration; therefore, additional analyses were done using BMI <30 as one group. To determine whether BMI had any effects on tracheostomy complication rate and procedure duration, low (BMI <30) and high (BMI 30) (according to National Institutes of Health [NIH] standards for obesity 4 ; Table I) patients were compared. We performed a 2 (BMI: low, high) 3 2 (gender), ANOVA first with complication rate as the dependent variable then with procedure duration as the dependent variable. Relative risk of obesity on tracheostomy complications was calculated. To determine how varying levels of BMI affected complication rate and procedure duration, we stratified BMI into four groups based on NIH criteria and calculated a univariate ANOVA. To determine the relationship between BMI and the timing of complications, we completed separate v 2 tests of independence with BMI (low, high) and presence or absence of complication type (intra, early, and late). To determine whether neck circumference was predictive of complications or procedure duration, we ran two-tailed independent samples t tests on two neck circumference groups divided by the median neck circumference (45 cm). Hierarchical multiple regression was used to assess the ability of BMI and procedure duration to predict number of complications. Results were considered statistically significant for P values <.05. RESULTS During the study period, the otolaryngology service performed 165 tracheostomies. Fourteen patients with No. of patients 82 69 Age, yr Mean 54.9 51.3 Range 19 82 21 84 Gender Female 29 34 Male 53 35 Ethnicity African American 37 33 Caucasian 43 32 Asian 1 0 Hispanic/Latino 1 3 Native American 0 1 No. of days intubated Mean 7.3 10.2 Range 0 40 0 21 BMI Mean 22.6 49.8 Range 15.1 29.9 30.5 84.6 Neck circumference, cm Mean 40.1, n 5 48 50.4, n 5 56 Range 25 59.5 34 73 prior tracheostomy were excluded, leaving 151 patients as the basis of the analyses. Fifty-four percent had a BMI <30, and 46% had a BMI 30. Thirty-seven percent in the BMI <30 group were female, and 49% in the BMI 30 group were female; groups were similar in age and ethnicity. Patient demographics are listed in Table II. Indications for tracheostomy are listed in Table III. Within the obese group, there were 10 patients in obesity class I, 14 patients in obesity class II, and 45 patients in obesity class III. The neck circumference at the cricoid cartilage was measured in 48 patients with BMI <30 and averaged 40.1 cm. Neck circumference was measured in 56 patients with BMI 30 with an average of 50.4 cm. Neck circumference was significantly correlated with BMI (P <.0001). TABLE III. Indications for Tracheostomy. BMI <30 BMI 30 Head and neck cancer 24 1 Airway obstruction 13 11 Prolonged ventilation 40 37 Obstructive sleep apnea 0 17 Trauma 3 1 Other 2 2 106

TABLE IV. Additional Procedures Performed at the Same Time as Tracheostomy. BMI <30 BMI 30 Head and neck cancer resection 4 0 Direct laryngoscopy/biopsy 19 3 Facial fracture repair 1 0 Submental lipectomy 2 13 Abscess drainage 0 1 Laceration repair 0 1 Total 26 18 Tracheostomy was performed emergently in 15 patients (18%) with a BMI <30 and four patients (6%) with a BMI 30. Additional procedures were performed at the same time as tracheostomy in 26 patients (32%) in the BMI <30 group; the majority were related to head and neck cancer (direct laryngoscopy, cancer resection) (Table IV). In the BMI 30 group, 18 patients (26%) had an additional procedure, and 72% of those were submental lipectomy. Because univariate analyses of variance (ANOVA) revealed no significant effects of age or race on BMI, we collapsed across these variables in all remaining analyses. A one-way ANOVA revealed a main effect of gender on BMI (P 5.024). Women (n 5 63) had a mean BMI of 38.71 (standard deviation [SD] 5 18.03), whereas men (n 5 88) had a mean BMI of 32.40 (SD 5 15.84). Effect of Low (<30) Versus High BMI Sixteen (19.5%) patients with BMI <30 experienced a tracheostomy-related complication, and 38 (55%) obese patients experienced a total of 45 complications (Fig. 1). There was a greater number of each complication type, except for wound infection, in obese patients despite the smaller sample size. There was a statistically significant Fig. 2. Effect of degree of obesity on number of complications. Mean number of complications by the National Institutes of Health BMI Obesity Classification. There were significantly more complications in the obesity class II (BMI 35 39.9) group compared to BMI <30 patients (P 5.008), and in the obesity class III (BMI 40) group compared to the BMI <30 patients (P <.0001). BMI 5 body mass index. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.] difference in the number of desaturations (P 5.016), and tracheostomy site granulation approached significance (P 5.07). There was one code and no deaths in the BMI <30 group, and two codes and one death in the BMI 30 group. We ran a 2 (BMI: low, high) 3 2 (gender) ANOVA with complication rate as the dependent variable, which revealed a significant main effect of BMI on the number of complications (P <.0001). There was no main effect of gender and no interaction between BMI and gender. Relative risk calculation revealed a 2.823 increased risk of tracheostomy complications in obese patients. We also performed a 2 (BMI: low, high) 3 2 (gender) ANOVA with procedure duration as the dependent variable. Procedure duration was recorded in 101 patients and ranged 7 to 120 minutes. Participants with a low BMI (n 5 53) had a mean procedure duration of 24.74 minutes (SD 5 9.41), whereas participants with a high BMI (n 5 48) had a mean procedure duration of 46.17 minutes (SD 5 24.60). The ANOVA revealed a significant main effect of BMI on procedure duration (P <.0001). There was no main effect of gender, and no interaction between BMI and gender. There was, however, no significant difference in whether the procedure was done in the operating room versus intensive care unit (P 5.078). Hierarchical multiple regression was used to assess the ability of BMI and procedure duration to predict number of complications, and procedure duration did not account for a significant amount of additional variance. Fig. 1. Types of complications by BMI group. Patients in the BMI <30 group had no desaturation, skin breakdown, or false passage. All complication types were represented in the BMI 30 group. There were greater numbers of each type of complication in obese patients except wound infection. BMI 5 body mass index; SGS 5 subglottic stenosis. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.] Effect of Degree of Obesity To determine how varying levels of obesity affect complications, we stratified BMI into four groups: BMI <30 (n 5 82), obesity class I (n 5 10), obesity class II (n 5 14), and obesity class III (n 5 45). Figure 2 shows the means for number of complications across the four groups. A univariate ANOVA revealed a significant main effect of BMI stratification on the total number of complications (P 5.001). Post hoc least significant difference 107

Fig. 3. Effect of degree of obesity on procedure duration. Procedure duration was significantly longer for patients with obesity class II (BMI 35 39.9) (P <.0001) compared to BMI <30 and obesity class III (BMI 40) (P <.0001) compared to BMI <30 patients. There was also a significant difference between obesity class I (BMI 30 34.9) patients and obesity class II patients (P 5 0.24), and between obesity class I and obesity class III patients (P 5 0.27). [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.] tests of comparison revealed no significant difference between the BMI <30 group and obesity class I group, but did reveal significant differences between the BMI <30 group and obesity class II group (P 5.008) and between the BMI <30 and obesity class III group (P <.0001). To determine how varying levels of BMI affect procedure duration, we again stratified BMI into four groups: BMI <30 (n 5 53), obesity class I (n 5 5), obesity class II (n 5 8), and obesity class III (n 5 35). Figure 3 shows means for procedure duration across the four groups. A univariate ANOVA revealed a significant main effect of BMI stratification on procedure duration (P <.0001). Post-hoc least significant difference tests of comparison revealed no difference between the BMI <30 group and obesity class I group, but did reveal significant differences between the BMI <30 group and obesity class II group (P <.0001) and between the BMI <30 group and obesity class III group (P <.0001). There was also a significant difference between the obesity class I group and obesity class II group (P 5.024) and a significant difference between obesity class I group and obesity class III group (P 5.027). Effect of BMI on Complication Timing In the BMI <30 group, there were zero intraoperative complications, nine early, and seven late; in the obese group, there were four patients with intraoperative complications, 22 with early, and 12 with late (Fig. 4). To determine the relationship between BMI and timing of complications, we completed separate v 2 tests of independence with BMI (low, high) and presence or absence of each complication type (intra, early, late). The relation between BMI and intratracheostomy complications was significant: v 2 (1, N 5 151) 5 4.88 (P 5.027). The relation between BMI and early tracheostomy complications was significant: v 2 (1, N 5 151) 5 10.33 (P 5.001). The relation between BMI and late 108 Fig. 4. Timing of complication by BMI group. There were significantly more complications in patients with a BMI 30 in the intraoperative (P 5 0.27) and early postoperative (P 5.001) time periods. [Color figure can be viewed in the online issue, which is available at www.laryngoscope.com.] tracheostomy complications was not statistically significant: v 2 (1, N 5 151) 5 2.58 (P 5.108). Neck Circumference Neck circumference was significantly correlated with BMI (P <.0001). There were no effects of race/sex/ age on neck circumference, so we collapsed across these variables for further analysis. Two-tailed independent samples t tests on two neck circumference groups divided by the median neck circumference (<45 cm vs. 45 cm) revealed significant effects on both number of complications (P 5.012) and procedure duration (P 5.002). DISCUSSION The benefits of tracheostomy in the critically ill patient are well known. 5 In tracheostomy as with any procedure, these benefits must be weighed against the potential risks of the procedure. Obese patients raise concerns regarding the technical difficulty in performing tracheostomy due to anatomic variations, such as difficulty in palpating anterior neck landmarks, 6 excessive submental and upper thoracic tissue obstructing the surgical field, difficulty extending the neck, the thickness of tissues overlying the trachea, the posteroanterior slant of the trachea due to excess adipose tissue between the sternum and the trachea, a short neck displacing the airway structures inferiorly into the chest, 7 and difficulty with standard tracheostomy tube curvature conforming to the anatomy in obese patients. 8 These anatomic concerns are added to medical concerns such as decreased pulmonary reserve, medical comorbidities, and additional anesthetic risks. 9 Several studies have been published regarding the safety of percutaneous dilational tracheostomy (PDT) in obese patients; however, the results of these studies are mixed and limited by sample size, lack of follow-up, lack of controls, and the retrospective nature. 10 15 Byhahn et al. 11 observed a 43.8% complication rate for PDT in 32 obese patients versus 18.2% in 73 nonobese patients

(P <.001). Aldawood et al. 10 reported a significantly higher major complication rate after PDT when comparing 50 obese patients with 177 nonobese patients (12% vs. 2%, P 5.04). Conversely, in comparing 25 obese patients undergoing PDT with bronchoscopic assistance to 80 nonobese patients undergoing the procedure, no difference in operative (8% vs. 7.5%, P 5 1) or early (8% vs. 2.5%, P 5.2) complications was found. 15 In the largest comparative study to date, McCague et al. 14 compared 131 obese patients with 295 nonobese patients undergoing PDT with bronchoscopy and found no difference in complications. Much of the existing literature on open tracheostomy in obese patients focuses on description of surgical technique and selection of tracheostomy tube. 7,16 21 Darrat and Yaremchuk 2 determined that the mortality rate for 49 obese (defined as BMI 35) patients was 28.6% and for the 229 nonobese patients 17.9%, which was determined to be marginally significant (P 5.09). This difference was less significant when adjusted based on case mix index. Gross et al. 17 described the defatting tracheostomy and found a 43% complication rate in 23 patients with a BMI range of 39.2 to 73.5 (mean 55.9), but did not have a control group for comparison. The only large-scale comparative study of open tracheostomy complications in obese patients in the English literature was published by El Solh and Jaafar in 2007. 3 They retrospectively collected data on all tracheostomies performed during a 6-year period and compared complications in 89 patients with BMI 40 with complications in 338 patients with BMI <40. Data were collected until hospital discharge, and complications were classified as early if they occurred in the first 7 days postoperatively and late if >7 days. The incidence of complications in morbidly obese patients was 25% versus 14% in patients with BMI <40 (P 5.03), with two deaths in each group. Morbidly obese patients were found to be at a higher risk for serious life-threatening complications. Age, BMI, and Charlson Comorbidity Index were found to have a significant impact on complications, but only BMI was independently associated with an increased risk of tracheostomy-related complications. By prospectively collecting data, the present study seeks to more thoroughly explore tracheostomy-related complications in obese patients. Neck circumference was also recorded in 104 patients and was significantly greater in the obese group. Because neck circumference was measured at the level of the cricoid cartilage, this was intended to indicate difficulty in palpating landmarks for the procedure. Husein and Massick 6 suggested cricoid palpability as an indicator for safety of tracheostomy at the bedside. They found that patients with a palpable cricoid cartilage had a significantly reduced complication rate (2%) compared with those without palpable cricoid cartilage (22%). This correlates with our data that fewer tracheostomies were performed at the bedside in obese patients than nonobese patients (28% vs. 40%), though this difference was not significant. In our study, the second most common indication for tracheostomy in the obese group was obstructive sleep apnea (OSA). OSA adds physiologic issues that make the procedure more challenging, including decreased pulmonary reserve and hypercarbia. Also, in the obese group, the most common additional procedure was submental lipectomy, and the submental lipectomy operative site introduces additional complications. In fact, three of the episodes of bleeding in obese patients were from the lipectomy site. Procedure duration was recorded as an indicator of technical difficulty. Procedure duration was significantly increased in obese patients, particularly for patients with a BMI 35. These findings reflect the anatomic challenges presented by most obese patients and the additional intraoperative measures required. Increased duration adds an element of risk to any procedure. The overall tracheostomy-related complication rate for obese patients in our study was 55%, greater than the 25% rate in the El Solh and Jafaar study 3 ; this may be due to the prospective nature of our study and our 1- year follow-up. The mortality rate in our study (1.4%) compares favorably with the 2% reported. 3 Our study shows a significant effect of BMI on number of complications, particularly BMI 35, and particularly during the procedure and through postoperative day 14. There was a higher absolute number of complications of nearly every type including the most life-threatening complications (mucous plug, accidental decannulation, desaturations, and false passage). Based on these findings, patients with a BMI 35 warrant particular attention to medical optimization prior to the procedure, intraoperative measures, and close monitoring until 14 days postprocedure. Our study shows an increased risk of several complications: bleeding, mucous plug, accidental decannulation, granulation tissue, subglottic stenosis, desaturation, skin breakdown, and false passage. Patients and families should be counseled prior to the procedure regarding the almost threefold increased risk of complications. The effect of medical comorbidities and anesthetic risk may be reduced by preoperative anesthesiology evaluation and good communication between the surgeon, anesthesiologist, and internal medicine physicians. As evidenced by the increased operative time required, tracheostomy in obese patients can be quite challenging and should be undertaken only by surgeons well experienced in tracheostomy technique. The preoperative surgical evaluation should include anatomic evaluation to determine whether submental lipectomy is absolutely necessary given the increased risk of bleeding and other potential wound complications associated with this component of the procedure. For cases in which excess tissue is a concern for intraoperative access to neck anatomy only, positioning and taping maneuvers should be utilized; however, if excess submental tissue is expected to cause tracheostomy care and wound problems or obstruction of the tube postoperatively, the additional risks of submental lipectomy are justified. Tracheostomy site lipectomy and careful attention to hemostasis will be required in all cases. Olsen and Pearson 21 summarized 11 points in performing a sleep apnea tracheostomy. The 11 points are: 1) preoperative video and counseling, 2) experienced 109

anesthesiologist, 3) superior and inferior skin flaps, 4) anterior cervical lipectomy, 5) division of thyroid isthmus, 6) Bjork flap sewn to inferior skin flap, 7) upper skin flap sewn to trachea, 8) medium-length tracheotomy tubes, 9) postoperative flexible fiberoptic examination, 10) tracheostomy care instructions, and 11) follow-up until the stoma tract epithelializes. All of these steps should be at least considered in this high-risk population. Their study predates availability of specialized tracheostomy tubes; presently, proximally extended or custom length tubes are recommended to minimize complications with accidental decannulation, tube dislodgement, and false passage. Endoscopy may be required to ensure proper tube size and position to minimize the risk of subglottic stenosis. Based on previous literature, bronchoscopy should be employed when the PDT technique is utilized. All personnel (including nurses, respiratory therapists, and resident physicians) must be educated regarding the increased risk of postoperative complications and strictly adhere to tracheostomy care procedures, especially during the first 14 days after the surgery. This includes frequent suctioning and hypervigilance to tube/ patient positioning as well as awareness of the specialized tracheostomy tube in place and the need to keep appropriate replacement tubes at the bedside. Due to the increased risk of granulation tissue and skin breakdown, nurses should be educated in proper and frequent tracheostomy site care procedures. Only physicians experienced in tracheostomy tube changes should perform the first tracheostomy tube change and ensure that the tract is well epithelialized before others are permitted to change the tube, always keeping in mind the increased distance from skin to the trachea. Our study may be limited by referral selection bias, because all patients were operated on by the otolaryngology service, and general surgery also performs tracheostomies (during the same time period, the general surgery service performed 47 tracheostomies at this hospital); therefore, results should be interpreted in the setting of otolaryngologists performing the tracheostomy. The decision regarding location of the procedure was made at the subjective discretion of the attending surgeon and may have had an effect on our results. Medical comorbidities and history of neck irradiation or chemotherapy were not recorded and may represent confounding variables. Finally, our hospital is part of a tertiary university medical center, and therefore these data may not apply to other hospital settings. CONCLUSION The tracheostomy complication rate is significantly higher in obese patients, especially those with a BMI 35. Tracheostomy in obese patients takes longer and results in more intraoperative and early postoperative complications. Obese patients and their family members should be counseled regarding the increased risk of complications, and patients with a BMI 35 should receive particular attention to intraoperative and early postoperative care to reduce their tracheostomy-related complication rate. Acknowledgments The authors thank Dr. Jamie Kimbrough for assistance with initiation of the study and data collection, and Dr. Tonya Bergeson for assistance with statistical analysis. BIBLIOGRAPHY 1. Flegal K, Carroll M, Ogden C, Curtin L. Prevalence and trends in obesity among US adults, 1999 2008. JAMA 2010;303:235 241. 2. Darrat I, Yaremchuk K. Early mortality rate of morbidly obese patients after tracheotomy. Laryngoscope 2008;118:2125 2128. 3. El Solh A, Jaafar W. A comparative study of the complications of surgical tracheostomy in morbidly obese critically ill patients. Crit Care 2007;11:R3. 4. 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