The complexities of nasal airflow: theory and practice.

The objective of this study was to investigate the effects of nasal valve area, valve stiffness, and turbinate region cross-sectional area on airflow rate, nasal resistance, flow limitation, and inspiratory "hysteresis" by the use of a mathematical model of nasal airflow. The model of O'Neill and Tolley (Clin Otolaryngol Allied Sci 13: 273-277, 1988) describing the effects of valve area and stiffness on the nasal pressure-flow relationship was improved by the incorporation of additional terms involving 1) airflow through the turbinate region, 2) the dependence of the flow coefficients for the valve and turbinate region on the Reynolds number, and 3) effects of unsteady flow. The model was found to provide a good fit for normal values for nasal resistance and for pressure-flow curves reported in the literature for both congested and decongested states. Also, by showing the relative contribution of the nasal valve and turbinate region to nasal resistance, the model sheds light in explaining the generally poor correlation between nasal resistance measurements and the results from acoustic rhinometry. Furthermore, by proposing different flow conditions for the acceleration and deceleration phases of inspiration, the model produces an inspiratory loop (commonly referred to as hysteresis) consistent with those reported in the literature. With simulation of nasal flaring, the magnitude of the loop, the nasal resistance, and flow limitation all show change similar to that observed in the experimental results.NEW & NOTEWORTHY The present model provides considerable insight into some difficult conundrums in both clinical and technical aspects of nasal airflow. Also, the description of nasal airflow mechanics based on the Hagen-Poiseuille equation and Reynolds laminar-turbulent transition in long straight tubes, which has figured prominently in medical textbooks and journal articles for many years, is shown to be seriously in error at a fundamental level.

Seventeen Cases of Primary Hyperparathyroidism in Pregnancy: A Call for Management Guidelines.

CONTEXT: The risks of primary hyperparathyroidism (pHPT) to pregnant women and their fetuses appear to increase commensurate with serum calcium levels. The management strategy for pHPT must be adapted in pregnancy and should reflect the severity of hypercalcemia. However, no guidelines exist to assist clinicians. METHODS: The experience of a high-volume multidisciplinary endocrine surgical service in treating a consecutive series of pregnant women with pHPT referred for parathyroidectomy is presented and data are compared with a nonpregnant cohort with pHPT. A review of pHPT and pregnancy outcomes in the literature is provided. RESULTS: Seventeen pregnant women and 247 age range-matched nonpregnant women with pHPT were referred for surgery over 11 years. Mean serum calcium level was higher in the pregnant cohort (2.89 vs 2.78 mmol/L; P = 0.03). Preoperative localization with ultrasound succeeded in eight pregnant women (47%) and sestamibi scanning did in two of six (33% imaged preconception), compared with 84 (34%) and 102 (42%) control subjects, respectively (not significant). Parathyroidectomy was performed under general anesthesia between 12 and 28 weeks' gestation with no adverse pregnancy outcomes resulting. Cure rate was 100% vs 96% in controls. CONCLUSION: pHPT in pregnancy is a threat to mother and child. Medical management may be appropriate in mild disease, but in moderate to severe disease, parathyroidectomy under general anesthesia in the second trimester is safe. Localization using ionizing radiation/MRI is unnecessary, because surgical intervention in a high-volume multidisciplinary setting has excellent outcomes. Guidelines on the topic would assist clinicians.

Face and content validity of sheep heads in endoscopic rhinology training.

BACKGROUND: The objective of this study was to assess the face and content validity of the sheep head model in endoscopic rhinology training. METHODS: This study was a prospective evaluation study. Experienced otolaryngologists and trainees were recruited to complete 7 endoscopic rhinology tasks on pre-prepared sheep heads. All participants completed a validated 20-item questionnaire using a 5-point Likert scale to assess the model across 4 domains: face validity (FV), global content (GC), task-specific content (TSC), and curriculum applicability (CTR). RESULTS: Participants, including 25 experienced otolaryngologists and 45 trainees, completed all tasks. There were no statistically significant differences between the 2 groups' ratings for FV, GC, or CTR (p = 0.50.7, 0.278, and 0.157, respectively). The model achieved median face validity of 4 (interquartile range [IQR]: 4 to 5) with the agreement of experienced surgeons and trainees alike (95% and 90%, respectively). The median global content was 4 (IQR: 4 to 5 and agreement of 88% and 87%. There was some variation in the rating of task-specific content. A total of 6 tasks achieved validity with the agreement of experienced otolaryngologists. The highest-rated tasks were "examination under anesthesia" and "foreign body retrieval." Participants agreed on curriculum incorporation, transferability, and recommendation to trainees (median: 5; IQR: 4 to 5 and 95% to 97% agreement). CONCLUSION: The sheep head model achieved face and content validity for endoscopic rhinology training. It is safe, affordable, and can aid early-years trainees in acquiring a range of basic endoscopic rhinology skills.

Evaluating thyroid nodules: predicting and selecting malignant nodules for fine-needle aspiration (FNA) cytology.

OBJECTIVE: To form and assess a set of diagnostic ultrasound criteria to select malignant nodules for fine-needle aspiration (FNA) cytology and reduce number of FNA biopsies. METHODS: In this prospective observational service evaluation study, 171 thyroid nodules that underwent FNA cytology were independently scored by two observers for established nodular sonographic characteristics for malignancy. The final diagnosis was confirmed by surgery or a 6-month follow-up in nodules with benign cytology. RESULTS: Logistic regression analysis and receiver operating characteristic curve analysis results indicate good and comparable predictive powers of certain ultrasound characteristics in predicting malignancy. The highest sensitivity in detecting malignancy was achieved when taking together the information of marked hypoechogenicity, microcalcification and mixed central/peripheral or central Doppler colour flow pattern. A sensitivity of 100 % and a specificity of 76 % were obtained in detecting malignant nodules using this criteria. CONCLUSIONS: Our study proposes a set of ultrasound and colour Doppler criteria to safely select malignant thyroid nodules for FNA cytology. MAIN MESSAGES: • There is a need to safely select malignant nodules for FNA cytology and reduce unnecessary FNA • Some ultrasound features are specific but none are independently/fully predictive of malignancy • We have prospectively tested a set of ultrasound criteria for selecting nodules for FNA cytology • Our ultrasound criteria detected malignant nodules with a 100 % sensitivity and 76 % specificity • A high sensitivity is clinically desirable as it selects many, if not all, malignant nodules for FNA.

Regulation of human eotaxin-3/CCL26 expression: modulation by cytokines and glucocorticoids.

Eotaxin-3 (CCL26) is a CC chemokine that signals exclusively via the CCR3 receptor and has eosinophil-selective chemoattractant activity. Comparison of Eotaxin-1 (CCL11) and Eotaxin-2 (CCL24), demonstrates differences in their expression profiles, cell specificity and effector kinetics, implying distinct biological actions. But little data in this regard have been reported for Eotaxin-3. We aimed to analyse the effect of Th2 cytokines and glucocorticoids on Eotaxin-3 mRNA expression in human lung epithelial cells and dermal fibroblasts; cells implicated in the pathogenesis of allergic asthma and allergic dermatitis respectively. Eotaxin-3 mRNA levels in primary dermal fibroblasts and NCI-H727 lung epithelial cells were determined by Northern hybridization. In contrast to Eotaxin-1, Eotaxin-3 mRNA expression was not detected in unstimulated cells. The Th2 cytokines IL-4 and IL-13 induced Eotaxin-3 expression in a time and dose dependent manner, with IL-4 demonstrating a 100-fold greater potency. Unlike Eotaxin-1, Eotaxin-3 mRNA expression was not induced by either tumour necrosis factor (TNF)-alpha or interleukin (IL)-1 beta alone. Both IL-4 and IL-13 acted synergistically with TNF-alpha in superinducing Eotaxin-3 mRNA expression. Dexamethasone pre-treatment diminished induction of Eotaxin-3 mRNA expression. We conclude that modulation of Eotaxin-3 mRNA expression by Th(2) cytokines is different from that of Eotaxin-1 and Eotaxin-2, further supporting a distinct biological role for Eotaxin-3.