No abstract

PediatricView is an evaluation project that began in 1999 and is located at Western Pennsylvania Hospital in Pittsburgh. It is affiliated with the hospital's Department of Pediatrics and Neonatology and was initiated as an adjunct to the neonatal developmental follow-up clinic. The purpose of Pediatric View is to provide developmental and functional vision evaluations to children who have ocular or cortical visual impairments. A team that includes a neonatologist and an individual who has expertise in child development and visual impairment conduct the evaluations. The evaluations are generally two hours in length, and a detailed report that provides specific follow-up intervention strategies is provided for each infant, child, or adolescent. Since 1999, more than 300 individuals with cortical visual impairment (CVI) have been evaluated at Pediatric View. In 2003, systematic data collection was initiated to monitor the progress of infants, children, and adolescents who have CVI. The data collection and analysis are based on two specific research questions: "Are there commonalities in the medical histories of infants, children, and adolescents who have CVI?" and "Is there measurable improvement in the functional vision of children who have CVI?"

ABSTRACT. We examined the centroid frequency (Fc) of the electromyogram power-frequency spectra from the costal (EMGco) and crural (EMGcr) diaphragms at functional residual capacity and at reduced end-expiratory lung volume (EELV) (induced by abdominal banding) in six anesthetized newborn piglets. EMGco and EMGcr were recorded from bipolar electrodes embedded in the costal and crural diaphragms respectively. A fast Fourier transformation of ECG free EMGco and EMGcr was used to compute the power-frequency spectra and calculate Diaphragmatic EMG power-frequency spectral analysis has been used to index diaphragmatic fatigue in newborns (1-3) and adults (4). Such analysis involves EMG monitoring in which the power or amplitude of the EMG signal is examined as a function of its various frequency components (5). The assignment of the label diaphragmatic fatigue rests on the observation that fatigue in limb skeletal muscle is associated with characteristic changes in the power of the EMG frequency components. These changes include I ) a rapid decrease in high-frequency power, 2) a progressive increase in low frequency power, and 3) a fall in the centroid or median frequency and high-to-low frequency ratio (6, 7). Supported by a grant from the West Penn Hospital Foundation. 61EMG power-frequency spectral analysis, however, can be affected by various changes in the environmental milieu of the muscle including alterations in ambient temperature (8), pH (9), and muscle blood flow (8) and by changes in muscle length/ configuration (10, 11). Few of these physiologic alterations have been examined with reference to the diaphragm (9, 12). No investigation has examined the effect of changes in lung volume (and, by inference, diaphragm length/configuration) on the EMG power-frequency spectrum of this muscle. Studies on appendicular muscle have demonstrated that EMG power shifts to lower frequencies with increasing muscle length (10, 1 1). In this regard, an increase in diaphragm length occurs when EELV is reduced (1 3-15). We, therefore, examined the effect that reductions in EELV have on the power-frequency spectrum of the costal and crural diaphragm of piglets. We hypothesized that a reduction in EELV would be associated with a significant decline in the EMG Fc of both the costal and crural diaphragm. MATERIALS AND METHODSFarm bred piglets, obtained from a local breeder who provided accurate times of farrowing, served as our study animals. Experiments were performed on six 1-to 3-d-old (weight 1.8 + 0.2 kg) piglets. Anesthesia was induced with halothane (1.0%) delivered in a background of 40% O2 via a securely fitting face mask. After cannulation of the femoral artery and vein, anesthesia was maintained with an i.v. combination of a-chloralose (50 mg/kg) and urethane (200 mg/kg); halothane administration was discontinued. Subsequent infusions of chloralose and urethane were given if the piglet developed jaw clonus. The trachea was surgically exposed and cut horizontally. A 3-mm inner diameter endotracheal tube with adapter was...