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Biomedical subjects

E D Michaelson

Publications and source records attributed to E D Michaelson.

12 recordsLinked to original sources
PubMed1979

Distribution of ventilation in normal children.

Measurements of closing volume and the distribution fo ventilation by both single-breath (SBN2) and multiple-breath nitrogen washout methods were obtained in 376 healthy boys and girls, ages 6 to 18 years. A closing volume could be demonstrated in 39 percent of the subjects, and closing volume expressed as percentage of vital capacity did not change with height. Closing capacity expressed as percentage of total lung capacity showed a slight decrease with height. The slope of phase III of the SBN2 curve decreased with height. Single compartment N2 washout curves were observed in 72 percent of the subjects, and the incidence of single compartment curves increased with age. In those subjects with two compartment N2 washout curves, the relative compartmental ventilation became more even with increasing height. Our observations suggest that parallel units among peripheral airways grow at different rates.

Adolescent↗
PubMed1978

A roentgenographic method for measuring nasal mucous velocity.

Nasal mucous velocity was estimated by following the motion of radiopaque discs of Teflon by means of a fluoroscopic image intensifier. From 5 to 10 discs were deposited on the superior surface of the inferior turbinate with a forceps. No local anesthesia was employed and the subjects experienced no discomfort. The linear velocity of the discs was obtained by playing the videotape onto a television monitor, measuring distance with a ruler, and dividing by elapsed time. Duplicate runs of 1-2 min, 15 min apart were very reproducible but runs at 4-h intervals or daily over a 5-day period had a coefficient of variation of 30%. Average nasal velocity for individual ranged from 0 to 22.5 mm/min and group means ranged from 6. 8 to 10.8 mm/min. There was no statistically significant difference in nasal mucous velocity between young and elderly subjects nor was there a sexual difference. The saccharin test of nasal mucous transport was unsatisfactory because of inability to repeat the test more often than 1-2 h and its propensity to produce mild discomfort in a significant number of subjects. Saccharin times did not correlate significantly with values of nasal mucous velocity.

Adult↗
PubMed1978

Effects of sulfuric acid aerosol on cardiopulmonary function of dogs, sheep, and humans.

Submicronic aerosol of sulfuric acid (H2SO4) originates from the burning of fossil fuels and discharge of vapor from the automobile engine equipped with the catalytic converter. This study was conducted to determine whether brief exposure to this aerosol in high concentrations adversely affects the cardiopulmonary system. In all studies, submicronic aerosol of sodium chloride was used as a control. Anesthetized dogs that breathed H2SO4 aerosol in concentrations up to 8 mg per m3 showed no effects on respiratory resistance, static lung compliance, and functional residual capacity. A 4-hour exposure to H2SO4 aerosol (4 mg per m3) produced no significant changes in mechanics of breathing, functional residual capacity, pulmonary and systemic arterial blood pressures, cardiac output, heart rate, and arterial blood gas tensions. Conscious sheep that breathed H2SO4 aerosol in concentrations up to 14 mg per m3 for 20 min had no alteration of tracheal mucous velocity in an immediate 3-hour follow-up period or 5 to 10 days later. Conscious sheep that breathed H2SO4 aerosol (4 mg per m3) for 4 hours had no significant alteration of tracheal mucous velocity immediately and 2 hours thereafter. Both normal and asthmatic adults breathing H2SO4 aerosol in concentrations up to 1 mg per m3 for 10 min showed no significant alteration of lung volumes, distribution of ventilation, ear oximetry, dynamic mechanics of breathing, oscillation mechanics of the chest-lung system, pulmonary capillary blood flow, diffusing capacity, O2 consumption, and pulmonary tissue volume. No delayed effects in pulmonary function nor exacerbation of bronchial asthma were observe during a follow-up period of a few weeks. The present study indicates that single exposure to submicronic H2SO4 aerosol does not produce an immediate or a delayed adverse effect on cardiopulmonary function in anesthetized dogs, conscious sheep, and normal and asthmatic adults.

Aerosols↗
PubMed1976

Systolic time intervals during +Gz acceleration.

Systolic time intervals (STI) were recorded in 8 healthy male volunteers before, during, and after 30-s exposures to +3 Gz, +5 Gz, and +7 Gz acceleration. Heart rate (HR) increased at all +Gz levels, as did the HR corrected QSIc interval, left ventricular ejection time (LVETc), preejection period (PEPc) and PEP/LVET. These changes in STI were also proportional to the +Gz level. At the higher +Gz levels, PEPc and PEP/LVET continued to increase early in the recovery period, but HR and all STI returned to control after 60 s of recovery. Although physiological variables other than myocardial contractility, such as preload and afterload may influence STI during +Gz the effects of +Gz on stroke volume (SV) and cardiac output (CO) were estimated using previously described relationships between STI and invasively determined indices of cardiovascular function. In general CO increased as SV decreased. During recovery, HR and CO fell and CO remained slightly below control levels, primarily because estimated SV remained low. This study demonstrates the feasibility of using STI to estimate noninvasively the transient changes in cardiovascular function during +Gz acceleration.

Acceleration↗
PubMed1975

Quantitative differences in the cellular yield of two bronchial brushes.

Two commercially available bronchial brushes were compared for their cellular yield. Specimens were obtained from 45 patients and 13 dogs by tracheal brushing via bronchofiberscopy. After extraction of the cells from the brushes, total cell count and the percentage of ciliated cells were determined in a hemacytometer. There was a large, significant difference in the number of cells obtained by the two brushes but no difference in the percentage of ciliated cells. Because the number of cells available for study may relate to the likelihood of making a positive cytologic diagnosis, the results suggest that bronchial brushes should be evaluated for their cellular yield.

Adult↗
PubMed1975

Pulmonary mechanics by spectral analysis of forced random noise.

The magnitude (Zrs) and phase angle (thetars) of the total respiratory impedance (Zrs), from 3 to 45 Hz, were rapidly obtained by a modification of the forced oscillation method, in which a random noise pressure wave is imposed on the respiratory system at the mouth and compared to the induced random flow using Fourier and spectral analysis. No significant amplitude or phase errors were introduced by the instrumentation. 10 normals, 5 smokers, and 5 patients with chronic obstructive lung disease (COPD) were studied. Measurements of Zrs were corrected for the parallel shunt impedance of the mouth, which was independently measured during a Valsalva maneuver, and from which the mechanical properties of the mouth were derived. There were small differences in Zrs between normals and smokers but both behaved approximately like a second-order system with thetars = 0 degree in the range of 5--9 Hz, and thetars in the range of +40 degrees at 20 Hz and +60 degrees at 40 Hz. In COPD, thetars remained more negative (compared to normals and smokers) at all frequencies and crossed 0 between 15 and 29 Hz. Changes in Zrs, similar in those in COPD, were also observed at low lung volumes in normals. These changes, the effects of a bronchodilator in COPD, and deviations of Zrs from second-order behavior in normals, can best be explained by a two-compartment parallel model, in which time-constant discrepancies between the lung parenchyma and compliant airway keep compliant greater than inertial reactance, resulting in a more negative phase angle as frequency is increased.

Adult↗
PubMedDate not supplied

Mucociliary transport in central and intermediate size airways: effect of aminophyllin.

Mucociliary transport and the percentage of ciliated cells were studied in large and intermediate sized airways (generations 0-3) of anesthetized mongrel dogs before and after aminophyllin administration. The mean percentage of ciliated cells decreased respectively from 22.0% and 25.4% in the trachea and main bronchi to 8.0% in the lobar and 2.7% in the segmental bronchi. The fastest mean mucous velocity was found in the trachea (4.9 mm/min, S.E. 1.0). Mucous velocity decreased 38% from the trachea to the main bronchi, 55% to the lobar bronchi, and 66% to the segmental bronchi. A positive correlation (r = 0.75) was demonstrated between mucous velocity and the percentage of ciliated cells. After aminophyllin administration, mucous velocity increased 59% in the trachea and 27% in the main bronchi. No statistical difference in mucous velocity could be demonstrated in the smaller airways after aminophyllin, probably due to relative insensitivity of the method in short bronchi with low mucous velocities.

Aminophylline↗
PubMedDate not supplied

Oxygen therapy and delivery in obstructive pulmonary disease.

The guidelines for O2 therapy in acute decompensation of COPD and even the indications for short-term use of O2 during periods of increased requirements in stable COPD are fairly clear-cut. With regard to continuous O2 therapy in hypoxemic patients with stable COPD, most would agree that in patients with cor pulmonale treatment with low concentrations of O2 for periods of more than 12 hours per day will result in improved pulmonary hemodynamics, mental function, polycythemia, and perhaps exercise tolerance. In similar patients without cor pulmonale the potential benefit of continuous O2 is unknown. Many other serious questions remain. The optimum duration of chronic O2 therapy must be clarified. More data are needed to determine the effect of continuous O2 therapy on mortality rate at both sea level and high altitude. It is not known whether O2 therapy has any prophylactic value in those patients with COPD who have not developed severe pulmonary hypertension. The potential value of O2 therapy in exercise rehabilitation programs needs further study. Finally, lightweight, longer-lasting, and less-expensive O2 delivery systems must be sought.

Carbon Dioxide↗