Histopathological effect of balloon dilation in a live rabbit: Implications for the pediatric airway.

OBJECTIVE/HYPOTHESIS: To examine the short- and long-term histopathologic changes that occur in the subglottis in response to airway balloon dilation (ABD) with different balloon diameters and inflation pressures. STUDY DESIGN: Prospective animal study using forty-two 8-month old New Zealand white rabbits at an academic animal research facility. METHODS: Thirty-nine live New Zealand rabbits underwent a single ABD with diameters ranging from 6.0 mm to 10.0 mm and with pressures between 5.0 atmospheres (atm) to 15.0 atm. Animals were euthanized on postoperative days (POD) 1, 7, and 30, and the histopathological changes of the subglottis were examined. Three rabbits served as controls and underwent no ABD. RESULTS: The subglottic airway diameter of all specimens measured 5.4 mm. When examining the fracture rate by balloon diameter, we found the following: 0 of 6 (0%) at 6 mm, 0 of 9 (0%) at 7 mm, 6 of 9 (67%) at 8 mm, 8 of 9 (89%) at 9 mm, and 6 of 6 (100%) at 10 mm. There was a statistically significant relationship with the rate of cricoid fracture as balloon diameter increased (P < .0001). All fractures occurred at the anterior cricoid lamina. On POD 1, we found mild ulceration in 5 of 6 (83%) using a 6-mm or 7-mm balloon and in 0 of 6 (0%) using an 8-mm, 9-mm, or 10-mm balloon; and moderate/severe ulceration in 1 of 6 (16.67%) using a 6-mm or 7-mm balloon and in 11 of 11 (100%) using an 8-mm, 9-mm, or 10-mm balloon (P < .0001). Also on POD 1, we found mild edema in 6 of 6 (100%) using a 6-mm or 7-mm balloon and in 5 of 11 (45%) using an 8-mm, 9-mm, or 10-mm balloon; and moderate/severe edema in 0 of 6 (0%) using a 6-mm/7-mm balloon and in 6 of 11 (55%) using an 8-mm, 9-mm, or 10-mm balloon (P =.048). On POD 7, we found fibroplasia in 5 of 6 (83%) using a 6-mm or 7-mm balloon and in 1 of 7 (14%) using an 8-mm, 9-mm, or 10-mm balloon; and moderate/severe fibroplasia in 1 of 6 (17%) using a 6-mm or 7-mm balloon and in 6 of 7 (86%) using an 8-mm, 9-mm, or 10-mm balloon (P =.029). Also on POD7, we found granulation tissue in 0 of 6 (0%) using a 6-mm or 7-mm balloon and in 5 of 7 (71%) using an 8-mm, 9-mm, or 10-mm balloon (P = .021). On POD 30, we found no fibrosis in 0 of 3 (0%) using a 7-mm balloon, mild fibrosis in 1 of 6 (16.67%), and moderate/severe fibrosis in 5 of 6 (83%) using an 8-mm or 9-mm balloon (P = .048). Also on POD 30, we found the mean subglottic cross-sectional luminal area was 23.79 mm(2) with a 7-mm balloon and 29.28 mm(2) with an 8-mm or 9-mm balloon (P = .019). Inflation pressure alone had no correlation with mucosal injury or probability of cricoid fracture. CONCLUSIONS: Airway balloon dilation with balloon diameters that exceeded the airway diameter by 2.6 mm was associated with cricoid fractures. All cricoid fractures localized to the anterior cricoid lamina. Balloon diameters larger than the airway diameter by 2.6 mm resulted in a larger subglottic cross-sectional luminal area on POD 30. Airway balloon dilation with balloon diameters that could generate a cricoid fracture created more mucosal injury on POD 0, 1, and 7 than smaller balloon diameters. The histopathological effects of airway balloon dilation observed on POD 0, 1, and 7 resolved by POD 30. When balloon diameter is kept constant, inflation pressure alone had no correlation with mucosal injury or probability of cricoid fracture. LEVEL OF EVIDENCE: NA (animal study). Laryngoscope, 125:S1-S11, 2015.

Feasibility and mortality of airway balloon dilation in a live rabbit model.

IMPORTANCE: Endoscopic balloon dilation is commonly performed in children with airway stenosis, but guidelines are needed for selecting safe and effective balloon inflation parameters. OBJECTIVE: To determine the feasibility and safety of airway balloon dilation in live rabbits using a range of balloon diameters and pressures. DESIGN AND SETTING: Prospective animal study using 32 adult New Zealand white rabbits with 1-week follow-up performed at an academic animal research facility. INTERVENTIONS: Rabbits underwent endoscopic laryngeal balloon dilation with diameters ranging from 6 to 10 mm and pressures of 5 to 15 atm. MAIN OUTCOMES AND MEASURES: Rabbits were observed for intraoperative complications and postoperative morbidity. RESULTS: All rabbit airways were sized to a 4-0 endotracheal tube (5.4-mm outer diameter). Balloon dilation was performed safely with no intraoperative complications in 25 of 30 cases. One rabbit developed transient cyanosis during balloon inflation. Three rabbits died while undergoing dilation with 10-mm balloons, and another rabbit developed respiratory failure shortly after the procedure. All rabbits that died perioperatively lacked endoscopic evidence of airway obstruction or gross trauma. Four rabbits developed postoperative feeding difficulties that did not correlate with balloon diameter or inflation pressure. CONCLUSIONS AND RELEVANCE: Endoscopic balloon dilation is generally well tolerated in New Zealand white rabbits. Intraoperative mortality from cardiopulmonary arrest reaches 50% when the balloon diameter exceeds the airway diameter by 4.6 mm. Postoperative feeding difficulties may occur with any balloon diameter or inflation pressure. Additional animal studies are necessary to determine the short- and long-term histologic effects of balloon dilation on the airway.

Patient adherence to allergy immunotherapy.

PURPOSE OF REVIEW: This article reviews the literature on patient adherence to two different approaches to allergen-specific immunotherapy for allergic disease. Factors related to adherence in general, as well as the various methods used to measure adherence, will be discussed. RECENT FINDINGS: Although a complex interaction of factors related to both the physician and the patient influence the adherence to a particular therapeutic regimen, effective communication between these two parties and the simplicity of the regimen are frequently noted to be of primary importance. Variability with respect to the definition of adherence, the method of measuring adherence, and the length of the measuring period has resulted in a wide range of adherence rates to allergy immunotherapy reported in the literature. Patients most often site inconvenience, side-effects, and poor efficacy as reasons for discontinuing allergy immunotherapy. SUMMARY: Adherence to therapy not only improves individual patient outcomes, but also helps determine the best treatment modalities and reduces the burden of disease on society. As new methods of delivering immunotherapy are being developed, such as allergy immunotherapy tablets and oral mucosal immunotherapy, the factors associated with patient adherence should be carefully considered.

Surgical factors in pediatric cochlear implantation and their early effects on electrode activation and functional outcomes.

OBJECTIVE: To assess the impact of surgical factors on electrode status and early communication outcomes in young children in the first 2 years of cochlear implantation. STUDY DESIGN: Prospective multicenter cohort study. SETTING: Six tertiary referral centers. PATIENTS: Children 5 years or younger before implantation with normal nonverbal intelligence. INTERVENTION: Cochlear implant operations in 209 ears of 188 children. MAIN OUTCOME MEASURES: Percent active channels, auditory behavior as measured by the Infant Toddler Meaningful Auditory Integration Scale/Meaningful Auditory Integration Scale and Reynell receptive language scores. RESULTS: Stable insertion of the full electrode array was accomplished in 96.2% of ears. At least 75% of electrode channels were active in 88% of ears. Electrode deactivation had a significant negative effect on Infant Toddler Meaningful Auditory Integration Scale/Meaningful Auditory Integration Scale scores at 24 months but no effect on receptive language scores. Significantly fewer active electrodes were associated with a history of meningitis. Surgical complications requiring additional hospitalization and/or revision surgery occurred in 6.7% of patients but had no measurable effect on the development of auditory behavior within the first 2 years. Negative, although insignificant, associations were observed between the need for perioperative revision of the device and 1) the percent of active electrodes and 2) the receptive language level at 2-year follow-up. CONCLUSION: Activation of the entire electrode array is associated with better early auditory outcomes. Decrements in the number of active electrodes and lower gains of receptive language after manipulation of the newly implanted device were not statistically significant but may be clinically relevant, underscoring the importance of surgical technique and the effective placement of the electrode array.