The introduction of pulse oximetry in clinical practice has allowed for simple, noninvasive, and reasonably accurate estimation of arterial oxygen saturation. Pulse oximetry is routinely used in the emergency department, the pediatric ward, and in pediatric intensive and perioperative care. However, clinically relevant principles and inherent limitations of the method are not always well understood by health care professionals caring for children. The calculation of the percentage of arterial oxyhemoglobin is based on the distinct characteristics of light absorption in the red and infrared spectra by oxygenated versus deoxygenated hemoglobin and takes advantage of the variation in light absorption caused by the pulsatility of arterial blood. Computation of oxygen saturation is achieved with the use of calibration algorithms. Safe use of pulse oximetry requires knowledge of its limitations, which include motion artifacts, poor perfusion at the site of measurement, irregular rhythms, ambient light or electromagnetic interference, skin pigmentation, nail polish, calibration assumptions, probe positioning, time lag in detecting hypoxic events, venous pulsation, intravenous dyes, and presence of abnormal hemoglobin molecules. In this review we describe the physiologic principles and limitations of pulse oximetry, discuss normal values, and highlight its importance in common pediatric diseases, in which the principle mechanism of hypoxemia is ventilation/perfusion mismatch (eg, asthma exacerbation, acute bronchiolitis, pneumonia) versus hypoventilation (eg, laryngotracheitis, vocal cord dysfunction, foreign-body aspiration in the larynx or trachea). Additional technologic advancements in pulse oximetry and its incorporation into evidence-based clinical algorithms will improve the efficiency of the method in daily pediatric practice.

Epidemiological studies have shown several associations between asthma symptoms and dietary factors. The aim of this work was to evaluate the relationship between adherence to the Mediterranean diet and childhood asthma. A cross-sectional analysis was performed on 700 children (323 boys), 10-12 yr old, selected from 18 schools located in Athens greater area. Children and their parents completed questionnaires, which evaluated, among others, dietary habits. Asthma was defined according to ISAAC II criteria. Adherence to the Mediterranean diet was evaluated using the KIDMED score (theoretical range 0-12). Higher KIDMED score corresponds to greater adherence to the Mediterranean diet. Greater adherence to the Mediterranean diet was inversely associated with ever had wheeze (p = 0.001), exercise wheeze (p = 0.004), ever had diagnosed asthma (p = 0.002) and with any asthma symptoms (p < 0.001). One-unit increase in the KIDMED score was associated with 14% lower likelihood of having asthma symptoms (odds ratio = 0.86, 95% confidence interval 0.75-0.98), after adjusting for various confounders. No significant associations were found between asthma symptoms and consumption of fruits (p = 0.25), vegetables (p = 0.97), legumes (p = 0.76), cereals (p = 0.71), dairy (p = 0.61), salty snacks (p = 0.53), or margarine/butter (p = 0.42) consumption, while increased fish and meat intake was associated with less asthma symptoms (p = 0.04 and p = 0.01, respectively). Our findings suggest an inverse relationship between level of adherence to the Mediterranean diet and prevalence of asthma in school-aged children.

BackgroundParticulate matter with diameter less than 10 micrometers (PM10) that originates from anthropogenic activities and natural sources may settle in the bronchi and cause adverse effects possibly via oxidative stress in susceptible individuals, such as asthmatic children. This study aimed to investigate the effect of outdoor PM10 concentrations on childhood asthma admissions (CAA) in Athens, Greece.MethodsDaily counts of CAA from the three Children's Hospitals within the greater Athens' area were obtained from the hospital records during a four-year period (2001-2004, n = 3602 children). Mean daily PM10 concentrations recorded by the air pollution-monitoring network of the greater Athens area were also collected. The relationship between CAA and PM10 concentrations was investigated using the Generalized Linear Models with Poisson distribution and logistic analysis.ResultsThere was a statistically significant (95% CL) relationship between CAA and mean daily PM10 concentrations on the day of exposure (+3.8% for 10 μg/m3 increase in PM10 concentrations), while a 1-day lag (+3.4% for 10 μg/m3 increase in PM10 concentrations) and a 4-day lag (+4.3% for 10 μg/m3 increase in PM10 concentrations) were observed for older asthmatic children (5-14 year-old). High mean daily PM10 concentration (the highest 10%; >65.69 μg/m3) doubled the risk of asthma exacerbations even in younger asthmatic children (0-4 year-old).ConclusionsOur results provide evidence of the adverse effect of PM10 on the rates of paediatric asthma exacerbations and hospital admissions. A four-day lag effect between PM10 peak exposure and asthma admissions was also observed in the older age group.

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