Impulse oscillometry: reference values in children 100 to 150 cm in height and 3 to 10 years of age.

OBJECTIVES: To generate reference equations in North American children to be used for assessing respiratory function through the forced oscillation (Rfo) technique, and to determine the changes in oscillatory resistance, reactance, and resonant frequency (Fres) in relation to age, body height, and weight. DESIGN/SETTING: A prospective cross-sectional study performed on healthy children selected according to strict criteria of American Thoracic Society and European Respiratory Society recommendations. MEASUREMENTS: Triplicate measures were obtained of resistance and reactance at 5, 10, 15, 20, 25, and 35 Hz as well as Fres through the impulse oscillometer (MasterScreen IOS; Jaeger/Toennies; Höchberg, Germany). Two hundred twenty-two white children--normally distributed within the 3- to 10-year age range and 100 to 150 cm in height--were recruited in Montreal, Canada. We used regression analysis to generate multiple predictive equations separately per gender and frequency on age, height, and body weight. RESULTS: Stepwise multiple regression in both natural and logarithmic forms for height, weight, age, and gender showed that standing height was the only significant predictor for all variables. Minimal variability was noted in each subject among the triplicate measurements (p = 0.68 to 0.96). Coherence was > 0.9 at all oscillating frequencies except 5 Hz (< 0.72), with tendencies to lower values in young children. CONCLUSIONS: Resistance and Fres decrease by height, but also by age; and reactance increases. As opposed to our past experience with spirometry in compatible age groups, the Rfo technique was well accepted by preschool children.

Neural network-longitudinal assessment of the Electronic Anti-Retroviral THerapy (EARTH) cohort to follow response to HIV-treatment.

HIV infection is for the most part a chronic and asymptomatic disease. To properly monitor the health status of infected individuals it is important to use host and viral surrogate markers as well as pharmacokinetic parameters. Disease progression, assessment of the antiviral potency of the drugs and response to therapy can only be monitored by repetitive measures of viral and host parameters. To prevent the emergence of antiviral drug-resistance, long term side effects and to decide on the appropriate treatment choices, a comprehensive assessment of all contributing factors, medical and non-medical, is necessary. However, the relationship between treatment outcomes with disease markers and other contributing factors is not simple. To date, a model that accurately predicts the likelihood of disease progression or treatment failure in HIV infected patients does not exist. Extending our previous work in this area, we developed temporal Artificial Intelligence models based on Jordan-Elman networks to longitudinally follow viral surrogate markers together with demographics, biochemical and laboratory data to describe the drug-virus-host interactions in over 4000 HIV adult patients. In an international (multi-continent) study of HIV clinical and laboratory data, the profiles of drug-naïve as well as treated patients were evaluated during a 20 year follow-up. Validation of models on a subset of this cohort (n=595) estimated the sensitivity and specificity of treatment success/failure, under different management modalities for individual patients. ROC-curves predicted: virologic success from baseline (ROC=0.871) in drug-naïve previously non-treated patients, switch from virologic success/ failure to failure/success if ever and when (ROC=0.625), switch to virologic success/failure from failure/success within 6 months (ROC=0.722) following a previous switch. This tool may be helpful in the design of longitudinal clinical trials.

Acoustic reflectance of pharyngeal structures in children.

The aim of this study was to examine whether Eccovision Reflectance Pharyngometer could assess the anatomical structure of the upper airway in young children. Secondary aims were to assess changes in pharyngeal volume in children with tonsillar (Group A, n=13) and adenoidal hypertrophy (Group B, n=17) at pre- and post- surgical procedures, respectively and further compare them to children who underwent myringotomy (Control Group C, n=10). In all 40 children (aged 3-9 years, median 6 years) enrolled in this pilot prospective study, six recordings (equally dispersed at pre- and 3 month post- operation per subject) of the pharyngeal cavity along with demographic (age, gender), somatic (standing and sitting height, body weight, head and neck circumference) and anatomic (bimaxilliary and bregma) characteristics, were captured. No significant intra-subject variability was noted within the multiple measurements of the pharyngeal volume at pre- as well as post-incision (ANOVA, P>0.1) in all groups. However, in Group A there was a marked increase from pre- to post-pharyngeal volumes in males (P=0.007), which was not observed in females (P=0.13). In Group B pharyngeal volumes decreased from pre- to post- in both males (P=0.87) and females (P=0.34). On the contrary, in Group C there was no change in pharyngeal volumes. These findings contradicted the visual evaluation of the size of the removed tonsillar and/or adenoidal mass in the first two groups and thus suggested that Eccovision Pharyngometer does not reliably assess pharyngeal volumes in a pediatric population.