Most current techniques to estimate respiratory system mechanical input impedance spectra (Zrs) use digitally created (Fourier transform (FFT) based) random noise. Recent Zrs data reported from 0.1-4 Hz and above 32 Hz display sharper, more distinct spectral features. When expressing Zrs as a power spectral density (PSD), such features suggest the application of a time series spectral estimation approach. Here, a simulation study was performed to compare the quality of impedance (PSD and Zrs) estimates from the time series technique to those from the FFT approach in the presence of measurement noise. Random noise pressure and flow time domain sequences were simulated for two different networks, one which exhibits impedance features reported from 0.1-4 Hz and one which exhibits impedance features reported above 32 Hz. In the time series method, autoregressive (AR), moving average (MA), and autoregressive-moving average (ARMA) models were fit to the pressure and flow sequences separately. The estimated PSD and complex Zrs spectra were compared to the true spectra calculated from the models. Results show that the time series PSD estimates were reasonable even in the presence of additive measurement noise. Conversely, with additive noise, the time series estimates of the complex Zrs showed a negative real part which is physiologically inappropriate. This occurs because of the loss of phase information inherent to the time series approach. Regardless of measurement noise, the FFT estimates of impedance were always close to the true impedance and always superior to the time series estimates. We conclude that an accurate estimate of the PSD or complex Zrs spectra from digitally created FFT-based random noise is best obtained using the traditional FFT method.

Airway Resistance↗

PubMedDate not supplied

Treatment-related central nervous system toxicity: MR imaging evaluation with CT and clinical correlation.

Thirteen patients with abnormal brain MR scans attributable to treatment-induced injury were retrospectively reviewed. All patients were treated with radiation therapy and 62% received chemotherapy. Five patients were graded as having severe white matter (WM) changes, four had moderate WM changes, and four had mild WM changes. CT was generally equivalent to MR in evaluation of severe and moderate WM abnormalities, whereas MR was superior to CT in detection of mild WM abnormalities. In general, the severity of changes depicted by MR/CT correlated with the extent of neurologic dysfunction. The most severe changes were seen in those patients treated with combination irradiation and chemotherapy.

Adolescent↗

PubMedDate not supplied

Central nervous system effects of chronic toluene abuse--clinical, brainstem evoked response and magnetic resonance imaging studies.

We describe the results of neurological evaluation, magnetic resonance imaging (MRI) of the brain and brainstem auditory evoked response (BAER) testing in 11 chronic toluene vapor abusers. Neurological abnormalities were seen in four of 11 individuals and included cognitive, pyramidal, cerebellar and brainstem findings. MRI of the brain was abnormal in three of 11 individuals and revealed the following abnormalities: 1) Diffuse cerebral, cerebellar, and brainstem atrophy; 2) Loss of differentiation between the gray and white matter throughout the CNS; and 3) Increased periventricular white matter signal intensity on T2 weighted images. BAERs were abnormal (control mean +/- 3 S.D.) in five of 11 individuals. As a group, the latency of V (p less than 0.01), the III-V interpeak (p less than 0.05) and the I-V interpeak latencies were prolonged compared to controls. All three individuals with abnormal MRI scans also had abnormal neurological examinations and BAERs. Two of five individuals with abnormal BAERs, however, had normal neurological examinations and MRI scans. Our data support previous findings of diffuse white matter involvement in chronic toluene abusers and suggest that BAERs may detect early CNS injury from toluene inhalation even at a time when neurological examination and MRI scans are normal. BAERs, therefore, may be a sensitive screening test to monitor individuals at risk from toluene exposure (either abusers or industrially exposed individuals) for early evidence of CNS injury.

Adult↗

PubMedDate not supplied

AIDS nursing care and standardized nursing language: an application of the nursing intervention classification.

Standardized nursing language is recommended increasingly as a method to describe the work of nursing, adapt to computerized documentation, and establish a place for nursing in national data bases. Nursing diagnosis has become a standard label for assessment data. The Iowa Interventions Project Research Team proposes that Nursing Interventions Classification (NIC) be adopted to label nursing interventions. The author applies NIC to HIV/AIDS nursing care guidelines from the literature and concludes that NIC can be an important tool as HIV/AIDS nurses develop and describe their knowledge base.

Guidelines as Topic↗

PubMedDate not supplied

MR imaging of heterotopic gray matter.

Magnetic resonance imaging is the current method of choice to diagnose heterotopic gray matter and associated cerebral malformations. We report a case of an epileptic child in whom heterotopic gray matter is present without any associated ventricular distortion.

Brain Neoplasms↗

PubMedDate not supplied

How your agency can organize a conference.

Explore the source record for details and available documents.

Congresses as Topic↗

PubMedDate not supplied

Development and evaluation of computer-based training for pre/post human immunodeficiency virus test counseling.

Computer-based instruction provides flexibility for staff development in the context of downsizing and rapid change in hospitals. There is an increasing need for nurse involvement in human immunodeficiency virus test counseling in hospitals and clinics because the Centers for Disease Control has recommended that human immunodeficiency virus testing be offered to all pregnant women. In this article, the author describes the development and evaluation of a computer-based instruction program to train nurses in human immunodeficiency virus test counseling.

AIDS Serodiagnosis↗