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Biomedical subjects

G Glass

Publications and source records attributed to G Glass.

48 records · Page 3Linked to original sources

Rib cage vs. abdominal displacement in dogs during forced oscillation to 32 Hz.

Allen et al. (J. Clin. Invest. 76: 620-629, 1985) reported that during oscillatory forcing the base of isolated canine lungs distends preferentially relative to the apex as frequency and tidal volume increase. The tendency toward such nonuniform phasic lung distension might influence phasic displacement of the rib cage (RC) relative to the abdomen (ABD). To test this hypothesis we measured RC and ABD displacement in four anesthetized dogs during forced oscillation. Sinusoidal volume changes were delivered through a tracheostomy at 1-32 Hz and measured by body plethysmography. RC and ABD displacements were measured by inductive plethysmography. During oscillation with air at fixed tidal volumes (10-80 ml) RC, normalized to unity at 1 Hz, increased to 2.06-2.22 at 8 Hz (P less than 0.001) and then decreased to 1.06-1.35 (P less than 0.0025) at 32 Hz. ABD, normalized to unity at 1 Hz, was 1.12-1.16 at 4 Hz (P less than 0.001) and decreased to 0.12-0.14 at 32 Hz (P less than 0.001). Displacement of ABD relative to RC did not increase systematically with increasing tidal volume during sinusoidal forcing at any frequency. Thus we found no discernible influence of nonuniform phasic lung distension on chest wall behavior. We infer that in the dog the nonuniform mechanical behavior of the chest wall dominates the nonuniform (but opposing) mechanical tendency of the lung.

Abdomen↗

Transition from dynamically maintained to relaxed end-expiratory volume in human infants.

Newborn infants, in contrast to adults, dynamically maintain end-expiratory lung volume (EEV) above relaxation volume. The purpose of this study was to determine at what age children develop a breathing strategy that is relaxed, i.e., determined by the mechanical characteristics of the lung and chest wall. Forty studies were performed in 27 healthy infants and children aged 1 mo to 8 yr during natural sleep. Volume changes were recorded with the use of respiratory inductance plethysmography (RIP). The volume signal was differentiated to yield flow. Flow-volume representations were generated for a random sample of the recorded breaths to determine the predominant breathing strategy utilized, i.e., relaxed, interrupted, or indeterminate. The respiratory pattern was predominantly interrupted below 6 mo of age and predominantly relaxed over 1 yr of age. Mixed patterns were observed in children 6-12 mo of age. The number of breaths that could not be classified (indeterminate) decreased with age. Respiratory frequency measured from the sample of breaths decreased with age and was accompanied by an increase in expiratory time. We conclude that a relaxed EEV develops at the end of the first year of life and may be related to changes in the mechanical properties of the chest wall associated with growth as well as changes in respiratory timing.

Analog-Digital Conversion↗

Measurement of CLL

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Journal Article↗

EEG's in an alcohol detoxification and treatment center.

EEG's were carried out on two hundred and one (201) alcoholics admitted to a four week treatment program. The majority were grossly intoxicated on admission and presented the usual differential problems during the first few days of hospitalization. In spite of therapeutic doses of medication before testing, 85% had totally normal EEG's and only 5.5% revealed clearly abnormal tracings. Of those for whom repeat records were later obtained, four of six with an abnormality showed a persistance of abnormality suggesting underlying organic dysfunction and not just "intoxication". EEG has a place in identification of the alcoholic patient at greater risk for neurological complications and may be useful in alerting the psychiatrist to obtain additional personal and family history, neurological examination, and when appropriate, further tests for potential structural abnormality. Routine use of structural tests such as computerized scan will aid in the identification of serious structural abnormalities but will not identify equally serious disorganizing functional abnormalities.

Alcoholism↗