528867
research-article2014
AORXXX10.1177/0003489414528867Annals of Otology, Rhinology & LaryngologyHart et al
Article
Impedance Probe Testing Prior to Pediatric Airway Reconstruction
Annals of Otology, Rhinology & Laryngology 2014, Vol. 123(9) 641–646 © The Author(s) 2014 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/0003489414528867 aor.sagepub.com
Catherine K. Hart, MD1,2,3, Alessandro de Alarcon, MD, MPH1,2,3, Meredith E. Tabangin, MPH4, Steven Hamilton, MD1,3, Michael J. Rutter, FRCS1,2,3, Scott P. Pentiuk, MD2,5, and Jose M. Garza, MD2,5
Abstract Objective: This study aimed to determine if preoperative impedance testing changed management and if testing was associated with surgical outcome in patients undergoing airway reconstruction. Methods: Retrospective review of patients who had impedance testing prior to airway reconstruction at a tertiary pediatric hospital from January 2010 to September 2011. Charts were reviewed for demographics, medical/surgical history, impedance testing, and surgical outcomes. Results: Fifty-seven patients were included. Forty-seven (82%) were premature. Forty-seven (82%) had a primary diagnosis of subglottic stenosis. Twenty-six (45%) had prior airway surgery. Thirty-six (63%) had gastroesophageal reflux and 21 (36%) had undergone fundoplication. Patients without fundoplication had a median 46 total reflux, 7 proximal, and 14.5 acidic events compared to a median 5 total reflux, 0 proximal, and 0 acidic events in patients with fundoplication. Impedance testing changed management in 22% (8/36) of nonfundoplication patients and 9.5% (2/21) of fundoplication patients. In unadjusted analysis, fewer fundoplication patients had successful surgery compared to those without (33% vs 67%, P = .01). Prematurity, age at surgery, and previous airway surgery were also important predictors of surgical success. Conclusion: Fewer patients than anticipated had a change in management. Impedance testing was unlikely to change management in fundoplication patients. Patients with fundoplication were less likely to have a successful outcome, suggesting that factors other than reflux influence airway reconstruction outcomes. Keywords airway reconstruction, subglottic stenosis, gastroesophageal reflux, impedance testing
Introduction Gastroesophageal reflux disease (GERD) has long been thought to contribute to failures in airway surgery. Evidence suggests a connection between GERD and the development of subglottic stenosis, and studies in animal models have shown that gastric juices negatively affect mucosal healing after subglottic injury.1-5 In a rabbit model of laryngotracheal reconstruction (LTR), simulated GERD led to significant inflammation and subsequent cartilage necrosis.6 Given the potential negative effect of GERD on operative success, patients undergoing airway reconstruction at our institution are routinely evaluated for GERD prior to surgery. This evaluation can include esophagram, esophagogastroduodenoscopy (EGD) with biopsy, and pH-multichannel intraluminal impedance (pH-MII) testing. Testing with pH-MII technology combines standard pH monitoring with impedance monitoring, which allows for measurement of gas, liquid, and combined reflux events.7 The impedance sensors used in pH-MII do not rely on pH, making it possible to evaluate both acid and non-acid reflux
events, as opposed to a pH probe, which can evaluate only acidic events. pH-Multichannel intraluminal impedance is particularly useful in the setting of non-acidic or weakly acidic reflux (such as children on anti-reflux medication) and in children with suspected feeding-related reflux.7,8
1
Division of Pediatric Otolaryngology–Head & Neck Surgery, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA 2 Aerodigestive and Esophageal Center, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA 3 Department of Otolaryngology–Head & Neck Surgery, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA 4 Division of Biostatistics and Epidemiology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA 5 Division of Gastroenterology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA Corresponding Author: Catherine K. Hart, MD, Division of Pediatric Otolaryngology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, MLC 2018, Cincinnati, OH 45229, USA. Email: [email protected]
Downloaded from aor.sagepub.com at East Tennessee State University on June 23, 2015
642
Annals of Otology, Rhinology & Laryngology 123(9)
Although pH-MII testing is part of the preoperative evaluation in many patients prior to airway reconstruction at our institution, we lack data to guide which patients would benefit from such testing. pH-Multichannel intraluminal impedance testing is performed at the discretion of the individual providers without set guidelines to determine which patients should undergo pH-MII testing. This variation in practice was part of the impetus for the study. The goal of this study was to determine if preoperative impedance testing changed patient management and if testing correlated with surgical outcome in patients undergoing open airway reconstruction.
Materials and Methods After institutional review board approval was obtained, we identified all patients who underwent open airway reconstruction between January 2010 and September 2011 at Cincinnati Children’s Hospital Medical Center. We reviewed the charts of these patients to obtain demographic data, medical and surgical history, comorbidities, pH-MII testing results, and surgical outcomes. Patients without documented pH-MII testing were excluded from the study. In nearly all patients, the pH-MII probe was placed intraoperatively by a gastroenterology technician at the conclusion of the EGD. A plain radiograph was obtained postoperatively to confirm good position of the probe. Patients were admitted for overnight observation with the caregiver maintaining a log of events and symptoms while the probe was in place. pH-Multichannel intraluminal impedance uses sensors distributed throughout the esophagus to measure the resistance to a flow of current. There are 7 impedance sensors that generate 6 impedance channel waves throughout the esophagus, and based on impedance changes within these channels, it is possible to determine the directionality of the flow (eg, reflux event vs swallow) as well as the height of the refluxate. Because liquid and gas have different impedances (eg, resistance to a current flow), it is possible to differentiate the composition of the refluxed material (liquid, gas, or mixed). There is also a distal pH sensor in the catheter that measures whether the refluxate is acid (pH < 4) or non-acid (pH > 4). A liquid reflux episode was defined as a retrograde decrease in impedance to 50% of the baseline value or below, in at least the 2 distal impedance channels. A proximal event was defined as a reflux episode that reaches 1 of the 2 most proximal channels. Symptom associated probability (SAP) was calculated by automated software based on the temporal relationship between symptoms and all reflux events. Symptom associated probability was considered positive if the probability was greater than or equal to 95%. We examined the baseline characteristics including demographics, airway diagnosis, history of tracheostomy, history of prior airway surgery, diagnosis of GERD, proton
pump inhibitor (PPI) usage, history of gastrostomy tube placement, and history of Nissen fundoplication. A change in management was defined as a change in treatment or diagnosis. Successful surgical outcome was defined as surgical goal obtained following initial surgery. The goal of surgery was classified as decannulation or alleviation of stenosis. If the open airway reconstruction following impedance testing accomplished this goal, the surgery was deemed successful. Descriptive statistics were calculated on all variables. Distributions of continuous variables were evaluated for normality. Non-normally distributed variables are described as medians with ranges or interquartile ranges (IQRs). Since patients who have a history of fundoplication represent a specific subset of patients who have theoretically received the gold standard treatment for GERD, we examined impedance measures and tested differences between the groups using Wilcoxon rank sum tests. Chi-square tests or Fisher’s exact tests were used to examine relationships between categorical variables. Multivariable logistic regression was used to simultaneously examine several factors including history of fundoplication, age at surgery, prematurity, presence of a syndrome, previous airway surgery, pulmonary comorbidity, and neurologic comorbidity on the outcome of surgical success. Logistic regression models stratified by history of fundoplication were used to examine the role of preoperative impedance measures on changes in management and surgical success. Natural log transformations were used to normalize continuous impedance measures in regression models. All analyses were conducted using SAS (version 9.3; SAS Institute Inc, Cary, North Carolina, USA).
Results During the study period, 150 patients underwent open airway reconstruction. Of these, 57 (38%) underwent preoperative pH-MII testing and were included in the study. Demographic data and baseline characteristics are presented in Table 1. As shown, the majority of patients had a primary airway diagnosis of subglottic stenosis (n = 47, 82%). Thirty-six (63%) had a pre-existing diagnosis of GERD and 30 (52%) were already taking a PPI at the time of evaluation. The median duration of follow-up was 11 months (range, 1-31 months). Twenty-one patients had a history of fundoplication prior to pH-MII testing. Table 2 demonstrates the results of pH-MII testing for patients with a history of fundoplication compared to those without a fundoplication. Patients with a fundoplication had overall fewer reflux events. Eight patients (22%) without a fundoplication experienced a change in management compared to only 2 patients (9.5%) with a fundoplication. In unadjusted analysis, fewer patients with a fundoplication had a successful surgery compared to
Downloaded from aor.sagepub.com at East Tennessee State University on June 23, 2015
643
Hart et al Table 1. Study Population Characteristics. Study Population (n = 57)
Characteristic Demographics Sex, No. (%), male Premature, No. (%) Syndromic, No. (%) Age at time of impedance, median (range), y Age at time of surgery, median (range), y Airway history Primary airway diagnosis, No. (%) Subglottic stenosis Tracheal stenosis Laryngeal cleft Bilateral VCP TEF s/p tracheostomy, No. (%) s/p prior airway surgery, No. (%) ORSA screen negative GI history Diagnosis of GER, No. (%) On proton pump inhibitor, No. (%) s/p G-tube placement, No. (%) s/p Nissen fundoplication, No. (%)
31 (54) 47 (82) 7 (12) 2.9 (0.3-22.0) 3.9 (0.6-22.3)
47 (82.5) 4 (7) 3 (5.2) 2 (3.5) 1 (1.8) 54 (94.7) 26 (45.6) 42 (73.7) 36 (63) 30 (52.6) 23 (40.3) 21 (36.8)
Abbreviations: GER, gastroesophageal reflux; GI, gastrointestinal; G-tube, gastrostomy tube; ORSA, oxacillin-resistant Staphylococcus aureus; s/p, status post; TEF, tracheoesophageal fistula; VCP, vocal cord paralysis.
those without (33% vs 67%, P = .01). The multivariable model examining fundoplication and other factors indicated that prematurity, age at surgery, and previous airway surgery were also important predictors of surgical success. Overall, 10 patients (17.5%) had a change in management. Eight patients had a change in diagnosis, 7 patients had a medication change, and 5 patients had both (see Table 3). Odds ratios (ORs) for impedance measures predicting changes in management for patients without fundoplication are seen in Table 4. Too few patients with a fundoplication had a change in management (n = 2) to perform a regression analysis on these patients independently. When regression analysis was performed on the patients without fundoplication, the number of acidic events (OR = 2.8; 95% confidence interval [CI], 1.0-8.0; P = .05), the number of proximal events (OR = 3.3; 95% CI, 1.2-9.3; P = .02), and a positive SAP (OR = 5.6; 95% CI, 1.0-30.3; P = .05) were predictive of a change in management. Overall, a successful surgical outcome occurred in 31 patients (54%). Odds ratios for impedance measures on surgical outcome for patients with fundoplication and patients without fundoplication are presented in Table 5. None of the measures considered were predictive of successful outcome in the patients with a fundoplication. For patients without a fundoplication, the absence of postoperative complication
Table 2. Effect of Nissen Fundoplication on Impedance Characteristics. Nissen Without Nissen (n = 21) (n = 36) P Value Impedance results, median (IQR) Total reflux events 5 (1-16) 46 (27-70) Acidic events 0 (0-2) 14.5 (5.5-30) Non-acidic events 17 (3-24) 28.5 (13-49.5) Proximal events 0 (0-2) 7 (3-20.5) Percentage acid 0 (0-0) 0.15 (0.1-0.6) exposure time Change in 2 (9.5) 8 (22) management, No. (%) Successful surgical 7 (33) 24 (67) outcome, No. (%)
research-article2014
AORXXX10.1177/0003489414528867Annals of Otology, Rhinology & LaryngologyHart et al
Article
Impedance Probe Testing Prior to Pediatric Airway Reconstruction
Annals of Otology, Rhinology & Laryngology 2014, Vol. 123(9) 641–646 © The Author(s) 2014 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/0003489414528867 aor.sagepub.com
Catherine K. Hart, MD1,2,3, Alessandro de Alarcon, MD, MPH1,2,3, Meredith E. Tabangin, MPH4, Steven Hamilton, MD1,3, Michael J. Rutter, FRCS1,2,3, Scott P. Pentiuk, MD2,5, and Jose M. Garza, MD2,5
Abstract Objective: This study aimed to determine if preoperative impedance testing changed management and if testing was associated with surgical outcome in patients undergoing airway reconstruction. Methods: Retrospective review of patients who had impedance testing prior to airway reconstruction at a tertiary pediatric hospital from January 2010 to September 2011. Charts were reviewed for demographics, medical/surgical history, impedance testing, and surgical outcomes. Results: Fifty-seven patients were included. Forty-seven (82%) were premature. Forty-seven (82%) had a primary diagnosis of subglottic stenosis. Twenty-six (45%) had prior airway surgery. Thirty-six (63%) had gastroesophageal reflux and 21 (36%) had undergone fundoplication. Patients without fundoplication had a median 46 total reflux, 7 proximal, and 14.5 acidic events compared to a median 5 total reflux, 0 proximal, and 0 acidic events in patients with fundoplication. Impedance testing changed management in 22% (8/36) of nonfundoplication patients and 9.5% (2/21) of fundoplication patients. In unadjusted analysis, fewer fundoplication patients had successful surgery compared to those without (33% vs 67%, P = .01). Prematurity, age at surgery, and previous airway surgery were also important predictors of surgical success. Conclusion: Fewer patients than anticipated had a change in management. Impedance testing was unlikely to change management in fundoplication patients. Patients with fundoplication were less likely to have a successful outcome, suggesting that factors other than reflux influence airway reconstruction outcomes. Keywords airway reconstruction, subglottic stenosis, gastroesophageal reflux, impedance testing
Introduction Gastroesophageal reflux disease (GERD) has long been thought to contribute to failures in airway surgery. Evidence suggests a connection between GERD and the development of subglottic stenosis, and studies in animal models have shown that gastric juices negatively affect mucosal healing after subglottic injury.1-5 In a rabbit model of laryngotracheal reconstruction (LTR), simulated GERD led to significant inflammation and subsequent cartilage necrosis.6 Given the potential negative effect of GERD on operative success, patients undergoing airway reconstruction at our institution are routinely evaluated for GERD prior to surgery. This evaluation can include esophagram, esophagogastroduodenoscopy (EGD) with biopsy, and pH-multichannel intraluminal impedance (pH-MII) testing. Testing with pH-MII technology combines standard pH monitoring with impedance monitoring, which allows for measurement of gas, liquid, and combined reflux events.7 The impedance sensors used in pH-MII do not rely on pH, making it possible to evaluate both acid and non-acid reflux
events, as opposed to a pH probe, which can evaluate only acidic events. pH-Multichannel intraluminal impedance is particularly useful in the setting of non-acidic or weakly acidic reflux (such as children on anti-reflux medication) and in children with suspected feeding-related reflux.7,8
1
Division of Pediatric Otolaryngology–Head & Neck Surgery, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA 2 Aerodigestive and Esophageal Center, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA 3 Department of Otolaryngology–Head & Neck Surgery, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA 4 Division of Biostatistics and Epidemiology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA 5 Division of Gastroenterology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA Corresponding Author: Catherine K. Hart, MD, Division of Pediatric Otolaryngology, Cincinnati Children’s Hospital Medical Center, 3333 Burnet Avenue, MLC 2018, Cincinnati, OH 45229, USA. Email: [email protected]
Downloaded from aor.sagepub.com at East Tennessee State University on June 23, 2015
642
Annals of Otology, Rhinology & Laryngology 123(9)
Although pH-MII testing is part of the preoperative evaluation in many patients prior to airway reconstruction at our institution, we lack data to guide which patients would benefit from such testing. pH-Multichannel intraluminal impedance testing is performed at the discretion of the individual providers without set guidelines to determine which patients should undergo pH-MII testing. This variation in practice was part of the impetus for the study. The goal of this study was to determine if preoperative impedance testing changed patient management and if testing correlated with surgical outcome in patients undergoing open airway reconstruction.
Materials and Methods After institutional review board approval was obtained, we identified all patients who underwent open airway reconstruction between January 2010 and September 2011 at Cincinnati Children’s Hospital Medical Center. We reviewed the charts of these patients to obtain demographic data, medical and surgical history, comorbidities, pH-MII testing results, and surgical outcomes. Patients without documented pH-MII testing were excluded from the study. In nearly all patients, the pH-MII probe was placed intraoperatively by a gastroenterology technician at the conclusion of the EGD. A plain radiograph was obtained postoperatively to confirm good position of the probe. Patients were admitted for overnight observation with the caregiver maintaining a log of events and symptoms while the probe was in place. pH-Multichannel intraluminal impedance uses sensors distributed throughout the esophagus to measure the resistance to a flow of current. There are 7 impedance sensors that generate 6 impedance channel waves throughout the esophagus, and based on impedance changes within these channels, it is possible to determine the directionality of the flow (eg, reflux event vs swallow) as well as the height of the refluxate. Because liquid and gas have different impedances (eg, resistance to a current flow), it is possible to differentiate the composition of the refluxed material (liquid, gas, or mixed). There is also a distal pH sensor in the catheter that measures whether the refluxate is acid (pH < 4) or non-acid (pH > 4). A liquid reflux episode was defined as a retrograde decrease in impedance to 50% of the baseline value or below, in at least the 2 distal impedance channels. A proximal event was defined as a reflux episode that reaches 1 of the 2 most proximal channels. Symptom associated probability (SAP) was calculated by automated software based on the temporal relationship between symptoms and all reflux events. Symptom associated probability was considered positive if the probability was greater than or equal to 95%. We examined the baseline characteristics including demographics, airway diagnosis, history of tracheostomy, history of prior airway surgery, diagnosis of GERD, proton
pump inhibitor (PPI) usage, history of gastrostomy tube placement, and history of Nissen fundoplication. A change in management was defined as a change in treatment or diagnosis. Successful surgical outcome was defined as surgical goal obtained following initial surgery. The goal of surgery was classified as decannulation or alleviation of stenosis. If the open airway reconstruction following impedance testing accomplished this goal, the surgery was deemed successful. Descriptive statistics were calculated on all variables. Distributions of continuous variables were evaluated for normality. Non-normally distributed variables are described as medians with ranges or interquartile ranges (IQRs). Since patients who have a history of fundoplication represent a specific subset of patients who have theoretically received the gold standard treatment for GERD, we examined impedance measures and tested differences between the groups using Wilcoxon rank sum tests. Chi-square tests or Fisher’s exact tests were used to examine relationships between categorical variables. Multivariable logistic regression was used to simultaneously examine several factors including history of fundoplication, age at surgery, prematurity, presence of a syndrome, previous airway surgery, pulmonary comorbidity, and neurologic comorbidity on the outcome of surgical success. Logistic regression models stratified by history of fundoplication were used to examine the role of preoperative impedance measures on changes in management and surgical success. Natural log transformations were used to normalize continuous impedance measures in regression models. All analyses were conducted using SAS (version 9.3; SAS Institute Inc, Cary, North Carolina, USA).
Results During the study period, 150 patients underwent open airway reconstruction. Of these, 57 (38%) underwent preoperative pH-MII testing and were included in the study. Demographic data and baseline characteristics are presented in Table 1. As shown, the majority of patients had a primary airway diagnosis of subglottic stenosis (n = 47, 82%). Thirty-six (63%) had a pre-existing diagnosis of GERD and 30 (52%) were already taking a PPI at the time of evaluation. The median duration of follow-up was 11 months (range, 1-31 months). Twenty-one patients had a history of fundoplication prior to pH-MII testing. Table 2 demonstrates the results of pH-MII testing for patients with a history of fundoplication compared to those without a fundoplication. Patients with a fundoplication had overall fewer reflux events. Eight patients (22%) without a fundoplication experienced a change in management compared to only 2 patients (9.5%) with a fundoplication. In unadjusted analysis, fewer patients with a fundoplication had a successful surgery compared to
Downloaded from aor.sagepub.com at East Tennessee State University on June 23, 2015
643
Hart et al Table 1. Study Population Characteristics. Study Population (n = 57)
Characteristic Demographics Sex, No. (%), male Premature, No. (%) Syndromic, No. (%) Age at time of impedance, median (range), y Age at time of surgery, median (range), y Airway history Primary airway diagnosis, No. (%) Subglottic stenosis Tracheal stenosis Laryngeal cleft Bilateral VCP TEF s/p tracheostomy, No. (%) s/p prior airway surgery, No. (%) ORSA screen negative GI history Diagnosis of GER, No. (%) On proton pump inhibitor, No. (%) s/p G-tube placement, No. (%) s/p Nissen fundoplication, No. (%)
31 (54) 47 (82) 7 (12) 2.9 (0.3-22.0) 3.9 (0.6-22.3)
47 (82.5) 4 (7) 3 (5.2) 2 (3.5) 1 (1.8) 54 (94.7) 26 (45.6) 42 (73.7) 36 (63) 30 (52.6) 23 (40.3) 21 (36.8)
Abbreviations: GER, gastroesophageal reflux; GI, gastrointestinal; G-tube, gastrostomy tube; ORSA, oxacillin-resistant Staphylococcus aureus; s/p, status post; TEF, tracheoesophageal fistula; VCP, vocal cord paralysis.
those without (33% vs 67%, P = .01). The multivariable model examining fundoplication and other factors indicated that prematurity, age at surgery, and previous airway surgery were also important predictors of surgical success. Overall, 10 patients (17.5%) had a change in management. Eight patients had a change in diagnosis, 7 patients had a medication change, and 5 patients had both (see Table 3). Odds ratios (ORs) for impedance measures predicting changes in management for patients without fundoplication are seen in Table 4. Too few patients with a fundoplication had a change in management (n = 2) to perform a regression analysis on these patients independently. When regression analysis was performed on the patients without fundoplication, the number of acidic events (OR = 2.8; 95% confidence interval [CI], 1.0-8.0; P = .05), the number of proximal events (OR = 3.3; 95% CI, 1.2-9.3; P = .02), and a positive SAP (OR = 5.6; 95% CI, 1.0-30.3; P = .05) were predictive of a change in management. Overall, a successful surgical outcome occurred in 31 patients (54%). Odds ratios for impedance measures on surgical outcome for patients with fundoplication and patients without fundoplication are presented in Table 5. None of the measures considered were predictive of successful outcome in the patients with a fundoplication. For patients without a fundoplication, the absence of postoperative complication
Table 2. Effect of Nissen Fundoplication on Impedance Characteristics. Nissen Without Nissen (n = 21) (n = 36) P Value Impedance results, median (IQR) Total reflux events 5 (1-16) 46 (27-70) Acidic events 0 (0-2) 14.5 (5.5-30) Non-acidic events 17 (3-24) 28.5 (13-49.5) Proximal events 0 (0-2) 7 (3-20.5) Percentage acid 0 (0-0) 0.15 (0.1-0.6) exposure time Change in 2 (9.5) 8 (22) management, No. (%) Successful surgical 7 (33) 24 (67) outcome, No. (%)
