Geographic disparities in performance of pediatric polysomnography to diagnose obstructive sleep apnea in a universal access health care system.

BACKGROUND: Diagnostic polysomnography (PSG) is recommended prior to adenotonsillectomy (AT) for children with obstructive sleep apnea (OSA) and certain high-risk characteristics, but resource limitations often prevent this practice. OBJECTIVE: We performed a population-based assessment of children across Ontario, Canada to describe and quantify disparities in PSG. METHODS AND MATERIALS: This retrospective cohort study was performed using provincial health administrative data held at ICES. We identified children 0-10 years old who underwent PSG and AT between 2009 and 2018, and those with a PSG within 18 months prior to and/or 12 months following AT. We calculated the odds of PSG prior to/following AT after adjustment for demographics, medical comorbidities, geographic and socioeconomic characteristics. Our main predictor was driving time/distance to the nearest pediatric sleep centre ascertained using spatial analysis and geographic information systems. RESULTS: We identified 27,837 children <10 years old who underwent AT for OSA in Ontario. Only 12.8% had a PSG within 18 months prior and 5.7% had a PSG within 12 months following AT. Shorter driving time/distance, older age, male sex and certain comorbidities were associated with increased odds of PSG. CONCLUSION: Only a small proportion of children in our cohort underwent PSG prior to or following AT surgery despite universal access to healthcare. This study suggests a need to increase overall PSG access, particularly for those living distant from existing pediatric sleep centres. Future studies could determine if increased PSG testing in 'underserviced areas' would reduce overall surgery rates and/or improve health outcomes.

Question 3: Can we diagnose asthma in children under the age of 5 years?

The diagnosis of asthma in children under five years has been controversial due to changing concepts of what true asthma is in this age group. Previous diagnostic algorithms that used clinical indices to predict the persistence of asthma symptoms or phenotypes based on asthma triggers do not predict which children will benefit from asthma medication. A pragmatic approach to asthma diagnosis in this age group is based on identifying signs and symptoms of reversible airflow obstruction and documenting their response to asthma medication. Hopefully, this approach will provide clearer guidance to clinicians and improve asthma morbidity in these young children.

In vitro chemosensitivity profile of oral squamous cell cancer and its correlation with clinical response to chemotherapy.

CONTEXT: Oral cancers represent a disparate group of tumors with diverse clinical behavior and chemosensitivity profile. Currently, it is difficult to predict whether a tumor will respond to chemotherapy and which drug(s) will achieve the maximum clinical response. AIMS: To study in vitro chemosensitivity profile of oral cancers and to correlate the in vitro chemosensitivity of oral cancer to clinical response to chemotherapy. SETTINGS AND DESIGN: Prospective study in a tertiary cancer care center. METHODS AND MATERIAL: We prospectively studied the chemosensitivity profile of 57 untreated, advanced, unresectable oral cancers to cisplatin, methotrexate, 5-fluorouracil and their combinations by using histoculture drug response assay (HDRA) and correlated them to the clinical response to chemotherapy. STATISTICAL ANALYSIS USED: Chi Square test. RESULTS: Biopsy samples were successfully histocultured in 52/57 (91%) cases. Of these 52 evaluable patients, 47 had primary gingivo-buccal cancers and five had tongue / floor of mouth cancers. Based on the assay, 27 (52%) tumors were sensitive to cisplatin, 27 (52%) to methotrexate, 24 (46%) to 5-fluorouracil, 38 (73%) to combination of cisplatin and methotrexate and 36 (69%) to combination of cisplatin and 5-fluorouracil. Of these, 31 patients with good performance status received two cycles of chemotherapy using one or more of these test drugs. There was a significant correlation (p=0.03) between the in vitro chemosensitivity and the clinical response. Negative predictive value of the test was 80%, positive predictive value-69%, sensitivity-79% and specificity -71%. The overall accuracy of the assay was 74%. CONCLUSIONS: We found HDRA to be a fairly good predictor of chemo-response of oral cancer.

Puerperal seizures associated with post dural puncture headache.

We present a case of tonic-clonic seizure occurring on day four post partum and associated with severe post dural puncture headache. The possible underlying aetiologies of this and two other cases we have managed and the difficulty distinguishing such seizures from eclampsia are discussed.

Technique of distortion correction in endoscopic images using a polynomial expansion.

A new technique to correct non-linear distortion of endoscopic images based on L2-norm approximation is proposed. A mathematical model is defined that maps the endoscopic images from the distorted image plane onto an undistorted image plane. A set of model parameters is defined, consisting of the image distortion centre, corrected centre and expansion polynomial coefficients representing radial distortion correction. A new method to find the image distortion centre based on a curvature criterion is also developed. The expansion coefficients are estimated on the basis of the degree of straightness of the grid lines in an image of a test grid consisting of dots in a rectangular pattern. The corrected image centre is computed by ensuring that the distances between neighbouring test dots of different grid lines in the corrected image are the same. The quantitative data providing the results and errors of the expansion characteristics are presented. The performance of the proposed distortion correction algorithm is validated with grid patterns of different orientations. The algorithm is also applied to typical endoscopic images, and the results are presented. The high-speed response of the proposed technique is a key step towards on-line camera calibration.

A new approach for nonlinear distortion correction in endoscopic images based on least squares estimation.

Images captured with a typical endoscope show spatial distortion, which necessitates distortion correction for subsequent analysis. In this paper, a new methodology based on least squares estimation is proposed to correct the nonlinear distortion in the endoscopic images. A mathematical model based on polynomial mapping is used to map the images from distorted image space onto the corrected image space. The model parameters include the polynomial coefficients, distortion center, and corrected center. The proposed method utilizes a line search approach of global convergence for the iterative procedure to obtain the optimum expansion coefficients. A new technique to find the distortion center of the image based on curvature criterion is presented. A dual-step approach comprising token matching and integrated neighborhood search is also proposed for accurate extraction of the centers of the dots contained in a rectangular grid, used for the model parameter estimation. The model parameters were verified with different grid patterns. The distortion-correction model is applied to several gastrointestinal images and the results are presented. The proposed technique provides high-speed response and forms a key step toward online camera calibration, which is required for accurate quantitative analysis of the images.

Real-time automatic extraction of lumen region and boundary from endoscopic images.

A new approach to the automatic extraction of the lumen region and its boundary for gastrointestinal (GI) endoscopic images is presented. First, a quasi region of interest, the darker regions of the image, is segmented using a region splitting scheme termed progressive thresholding. The centre of mass of this segmented region acts as a seed for further processing. Then the lumen region is obtained using a region growing technique called the integrated neighbourhood search (INS). A new quad structure based technique is introduced to enhance the INS speed significantly. A back projection algorithm is suggested to optimise the search for pixels belonging to the lumen region and boundary. A boundary-thinning algorithm is also proposed to remove the redundant pixels from the lumen boundary and to generate a connected single pixel width boundary. The proposed approach does not need a priori knowledge about the image characteristics. The experimental results indicate that the proposed technique enhances the speed of conventional INS by 45.5% to 28.6% based on the lumen size varying from 22,709 pixels to 4947 pixels. The main advantage of the proposed technique is its high-speed response that facilitates real-time analysis of endoscopic images.

Haemodynamic effects of intravenous nimodipine following aneurysmal subarachnoid haemorrhage: implications for monitoring.

Nimodipine is widely used in patients with aneurysmal subarachnoid haemorrhage for the prevention and treatment of delayed ischaemic neurological deficits. Intravenous nimodipine has significant vasodilatory properties and may compromise the achievement of haemodynamic targets in patients who receive hypertensive hypervolaemic haemodilution therapy. We have studied 22 patients who received postoperative therapy with intravenous nimodipine and show that in a substantial minority (29%) hypotension was not reversed by simple volume loading or low doses of inotropes. Formal haemodynamic assessment in these patients showed widely varying haemodynamic variables, with differences in the need for inotropic and vasopressor therapy. We conclude that optimal haemodynamic management in this subgroup of patients will require the use of pulmonary artery catheterisation.