Sancak Yuksel

Role of the Mastoid in Middle Ear Pressure Regulation

Determine the role of mastoid volume in middle ear pressure (MEP) regulation. The hypothesis was that inert gas exchange between blood and middle ear (ME) is slower for larger mastoid volumes.

Effects of ciprofloxacin-dexamethasone on myringotomy wound healing.

Objective: To evaluate the effects of the ciprofloxacin‐dexamethasone (CDX) combination ototopical treatment after myringotomy on tympanic membrane (TM) healing in ears with eustachian tube obstruction (ETO) and unobstructed ears.

In vivo measurement of O2 and CO2 gas exchange across the human tympanic membrane

Conclusion. The hypothesis that the human tympanic membrane (TM) is permeable to CO2 and O2 at physiologic pressure gradients is supported but additional experiments need to be done to validate this methodology. Objective. Gas exchange between the middle ear and adjacent compartments determines the trajectory of middle ear pressure change. Little information is available regarding the permeability of the TM to physiological gases. This study aimed to determine in vivo if the human TM is permeable to O2 and CO2 at physiologic transTM pressure gradients. Subjects and methods. An ear canal (EC) probe (ECP) constructed from a custom-fitted acrylic body, a glass capillary tube enclosing an oil meniscus to maintain ambient ECP + EC pressure and a silica glass microtube linked to a mass spectrometer (MS) for measuring gas composition was hermetically sealed within one EC in each of 15 adults. ECP + EC volume was measured and gas samples were taken at 10 min intervals for 1 h. Epinephrine (1:100 000) was applied topically to the ipsilateral TM to decrease blood flow and the experiment was repeated. The ECP + EC pressures of O2 (32 AMU) and CO2 (44 AMU) were regressed on time and the slope divided by the predicted transTM partial-pressure gradients to yield estimates of transTM O2 and CO2 conductance. Results. Consistent with expectations for transTM gas exchange, ECP + EC O2 decreased and CO2 increased during the experiments. CO2 increase was faster after application of epinephrine to the TM. The ratio of O2/CO2 conductances was not consistent with the gas exchange through a primarily water or lipid diffusion barrier.

Applications for transoral robotic surgery in the pediatric airway

To report preliminary experience in the utilization of transoral robotic surgical (TORS) techniques in pediatric airway surgery.

Directional asymmetry in the measured nitrous oxide time constant for middle ear transmucosal gas exchange.

Objectives: Simple, 2-compartment mathematical models of middle ear (ME) transmucosal gas exchange reproduce observed ME pressure behavior. These models require input of an experimentally determined, lumped-parameter exchange constant for each represented gas species. Previous model applications assumed directional asymmetry for those parameters, which has not been experimentally validated. Methods: As a surrogate for the inert gas nitrogen (N2), for which exchange is too slow to be measurable, the nitrous oxide (N2O) transmucosal exchange constant for 16 ears of 8 monkeys was measured for positive and negative ME blood N2O gradients. Results: The paired exchange constants for each ear were highly correlated, but the ME-blood/blood-ME exchange constant ratio was approximately 13. Modeling shows this asymmetry to depend on the value of the arterial-venous/arterial-ME ratio, a variable in the exchange constant for perfusion-limited gases. Conclusions: These results support an asymmetric rate of transmucosal N2O and, by extension, N2 exchange for the ME. Because the primary controlling parameter for ME pressure behavior in the absence of eustachian tube opening is the rate of transmucosal N2 exchange, this effect needs to be incorporated into the simple 2-compartment exchange models for predictive accuracy. The gradient ratio dependence suggests that parameter-free modeling may require treating the ME mucosa as having a distributed gradient for certain gas species.

Transmucosal O2 and CO2 exchange rates for the human middle ear.

OBJECTIVE Estimate the transmucosal CO(2) and O(2) rate-constants for adult middle ears (MEs). METHODS Ten adults with healthy MEs had a unilateral myringotomy. A custom-fitted acrylic mold with a valved line to a mass spectrometer (MS) and central tube coupled to a 3-way valve and connected to a pressure transducer (the probe) was sealed with adhesive glue within the ipsilateral ear-canal. A second 3-way valve was attached to the probe valve, a flow-regulated tank gas source and paired syringes. Volumes of the ME and probe were measured. On sequential days, the probe+ME was washed for 15-min with 6% O(2), Balance N(2) and 25% O(2), 6% CO(2), Balance N(2) to create transmucosal CO(2) and O(2) gradients, respectively. After washing, the probe+ME was isolated from the gas source, and baseline and 10-min gas samples were obtained for MS analysis of gas partial-pressures. The rates of change in ME CO(2) and O(2) pressures were divided by their established transmucosal gradients to yield CO(2) and O(2) rate-constants. RESULTS The average (±STD) transmucosal CO(2) and O(2) rate-constants were 0.062 ± 0.034 (N=10, range: 0.032-0.119) and 0.011 ± 0.009 (N=8, range: 0.002-0.032)mmHg/min/mmHg, respectively. The average half-life for the CO(2) and O(2) gradient was 11.1 and 61.6 min. The average CO(2):O(2) rate-constant ratio was 8.1 ± 4.0 (N=8, range: 3.6-14.6). CONCLUSIONS For adult human MEs, transmucosal CO(2) exchange is rapid and much faster than transmucosal O(2) exchange. The estimated CO(2)/O(2) rate-constant ratio for the human ME is not consistent with that predicted for diffusion-limited gas exchange across a water-based barrier.

DNA damage in children with obstructive adenotonsillar hypertrophy.

Abstract The objective of this prospective, controlled study was to evaluate oxidative DNA damage in children with obstructive adenotonsillar hypertrophy. This study included 30 patients with obstructive adenotonsillar hypertrophy (male/female ratio, 3:2; age range, 3–9 y) scheduled to undergo tonsillectomy and adenoidectomy and 25 control subjects of similar age and sex with no adenotonsillar disease or airway obstruction. Urine and blood samples were obtained from each child for 8-hydroxy 2-deoxyguanosine (8-OhdG) and malondialdehyde (MDA) concentrations. There were significant differences in leukocyte (3.28 [0.69/106] vs 0.70 [0.15/106] dG) and urine 8-OhdG (8.22 [2.27/106] vs 5.26 [1.3/106] dG) levels in patients with obstructive adenotonsillar hypertrophy and healthy subjects (P < 0.001 for both). Plasma (2.98 [1.31] vs 1.14 [0.64] &mgr;M) and urine (1.77 [0.84] vs 0.56 [0.32] &mgr;M) MDA levels were also different (P < 0.001 for both). There were positive correlations between 8-OhdG in leukocyte DNA and plasma MDA (r = 0.648, P < 0.001) and between levels of urine 8-OhdG excretion and urine MDA (r = 0.588, P < 0.001). The DNA damage in children with adenotonsillar hypertrophy should be kept in mind, but further studies must be done with larger patient groups.

Resolution of airflow obstruction on polysomnography after laryngotracheal reconstruction with anterior tracheal wall suspension in a patient with DiGeorge Syndrome

DiGeorge Syndrome (DGS) may be associated with airway abnormalities including laryngomalacia and suprastomal collapse of the trachea (SCT), which may lead to sleep disordered breathing (SDB). We present a 4-year-old boy with DGS, SCT, and SDB by polysomnography (PSG) while the tracheostomy tube was capped. The patient underwent anterior tracheal wall suspension (ATWS) with concurrent tracheostomy decannulation. Following the repair, the patient experienced improved airway patency visually and by PSG with resolution of obstructive sleep apnea and hypoventilation. ATWS is an effective method to repair SCT in selected patients and may lead to early decannulation and improvement of SDB.

Accuracy of CO2 conductance predicted using a morphometric model of the middle ear mucosa

Conclusion. These results hold promise that morphometric analysis can be used to generate transMEM (middle ear mucosa) gas conductance estimates for MEM geometries representative of the shift from healthy to pathologic states (e.g. increased MEM thickness and capillary density). Objectives. Novel strategies to treat otitis media with effusion require a better understanding of how MEM geometry affects gas transport. Earlier studies developed techniques to empirically measure transMEM gas conductance and to estimate conductance using morphometric models of MEM geometry. We used chinchillas to determine the correspondence between experimentally measured transMEM CO2 conductance and that predicted by morphometric study of the MEM. Materials and methods. TransMEM CO2 conductance was measured unilaterally in 10 chinchillas; the animals were killed and the ME was removed and processed for morphometric analyses of MEM geometry. Results. The average measured and estimated transMEM CO2 conductances were 4.87±2.30×10−10 and 1.75±0.29×10−10 mol/s/mmHg, respectively. The magnitude and direction of the estimate error were similar for all ears, suggesting a fixed, negative bias to the estimate. A theoretically consistent source for this bias was identified as the representation of the true diffusional length within a 3-D geometry using a 2-D modeling platform. Best estimate correction for this effect based on available data significantly reduced the estimate bias.

Airway evaluation in children with single ventricle cardiac physiology

OBJECTIVE Children with single ventricle cardiac physiology (SVC) often require airway procedures as an adjunct to their care. Descriptive analysis with a focus on outcomes of airway procedures in SVC patients have not been fully described in the literature. METHODS Retrospective, single-center cohort review of 270 patients born between Aug-2007 and Jan-2017. Patients were identified by cardiac database for single ventricle pathophysiology. A subset of these patients were identified to have been evaluated by otolaryngology with airway evaluations and/or interventions. RESULTS 88/270 patients (32.6%) required investigation or intervention for airway pathology. The most frequent procedure was flexible fiberoptic laryngoscopy (58/88 patients); it was the only procedure performed in 40 patients. Seventeen patients required tracheostomies with an associated increased length of stay (p < 0.001). Patients with cardiac procedures involving dissection around the aortic arch were considered higher airway risk due to the threat of recurrent laryngeal nerve injury, and were more likely to have vocal cord paralysis (58%) compared to patients with lower risk procedures (21%; p < 0.001). However, on multivariate logistic regression, vocal cord paralysis did not statistically impact the odds for tracheostomy placement, although the presence of subglottic stenosis increased the odds ratio of tracheostomy by 14.7 (p = 0.02). CONCLUSIONS Children with SVC often require airway evaluation and intervention. Patients with high risk cardiac procedures had a higher risk of recurrent laryngeal nerve injury but the presence of subglottic stenosis was the best predictor for a tracheostomy. This study represents one of the largest series of SVC children evaluated for airway pathology.