Biomedical subjects
Publications and source records attributed to E O Attinger.
The relative performance of less developed countries in their health, demographic and economic sectors was assessed by means of comparative indices constructed with the help of a factor analysis. This approach reduces the problems usually associated with such indices, like the arbitrary weighting of their components.
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It is the purpose of this report to examine the process of burn care of hospitalized burn patients in the Commonwealth of Virginia over a 21 month period. Eighty-nine per cent of the hospitals within the state participated in the study, the results of which provide a positive indication of the performance of our statewide emergency medical service referral system. This system was successful in redistributing patients, with the more severely burned patients being treated in the specialty burn treatment facilities. The process of burn care within the hospital setting was also consistent with the patient's severity of injury.
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The incidence of minor burn injuries has been determined for the Commonwealth of Virginia during a 17-month period. The data set included all patients with burn injuries receiving treatment in the emergency department that did not require hospitalization. The risk of burn injury was calculated by age, race and sex. Examination of the data revealed large differences in the magnitude of age-specific incidence rates between men and women and the white and non-white population. Differences in the economic status of the population may explain a large proportion of the variation in the crude burn rates.
The incidence of serious burn injuries has been determined for the Commonwealth of Virginia during a 21 month period. The data set included all patients with burn injuries who entered the hospital and were considered to be in serious enough condition to require treatment in a hospital. The risk for burn injury was calculated by age, race and sex. Examination of the date revealed large differences in the magnitude of age-specific incidence rates between men and women and the white and nonwhite population. Differences in the economic status of the population may explain a large proportion of the variation in the crude burn rates.
The interaction of medullary and carotid chemoreceptors during mild stimulation was investigated in 44 experiments on 6 chloralose-urethane anesthetized mongrel dogs using a donor-perfused, bilateral carotid sinus preparation. The donor dog breathed hypoxic mixtures (average PaO2 of 78 mm Hg) and the experimental animal breathed hypercapnic mixtures (average PACO2 of 49 mm Hg) in order to separately or simultaneously stimulate both chemoreceptor areas at low levels. After 4 min, the changes of tidal volume (VT), respiratory rate (f) and minute ventilation (VI), as a percentage of the control value, were compared to test whether the sums of the changes for separate stimuli were the same as for simultaneous stimuli, i.e. additive chemoreceptor effects. The simultaneous stimuli had significantly (P less than 0.05) greater responses for VT (19% greater than 5%) and VI (42% greater than 13%), but not for f (23% = 9%). Stepwise multiple regression studies of the response/control ratios on the blood gas values showed that multiplicative interaction terms accounted for more of the variance than additive terms for VT, f and VI and yielded equations which had overall significant slopes. We conclude that this evidence demonstrates that the two chemoreceptor effects combine synergistically at low levels of stimulation.
We have investigated the respiratory control system with the hypothesis that, although many variables such as minute ventilation (VI), tidal volume (VT), breathing period (TT), inspiratory duration (TI), and expiratory duration (TE) may be observed, the controller functions more simply by manipulating only 2 or 3 of these. Thus, if tidal volume is the only independent variable, TI being determined by the "off-switch" threshold, these variables should have very similar time courses. Anesthetized dogs were subjected to CO2 breathing and carotid sinus perfusion to stimulate both chemoreceptors. The time series of the variables VI, VT, TT, TE, and TI as well as PACO2 were determined on a breath by breath basis. Derived characteristics of these time series were compared using Cluster Analysis and the latent dimensionality of respiratory control determined by Factor Analysis. The characteristics of the time series clustered into 4 groups: magnitude (of the response), speed, variability and relative change. One respiratory factor accounted for 86% of the variance for the variability characteristics, 2 factors for magnitude (91%) and relative change (85%) and 3 factors for speed (89%). The respiratory variables were analysed for each of the 4 groups of characteristics with the following results: VT and TI clustered together only for the magnitude and relative change characteristics where as TT and TE clustered closely for all four characteristics. One latent factor was associated with the [TT-TE] group and the other usually with PACO2.
Our experiments were designed to evaluate the combined influence of the mechanoreceptor and chemoreceptor control loops on the cardiovascular and respiratory systems. Both carotid sinus areas were isolated by a complete blind sac preparation in chloralose anesthetized dogs in which a flow probe had been implanted previously on the ascending aorta. The following variables were continuously monitored: central aortic pressure, heart rate, cardiac output, vascular resistance of a hind limb, tidal volume, respiratory rate, and oxygen consumption. While one sinus was submitted to step changes of pressure, the opposite sinus was kept at constant mean pressure. In addition, one sinus was perfused with either oxygenated of deoxygenated blood at constant flow rate. These studies show a definite interaction between the control loops initiated by the carotid sinus mechanoreceptors and those initiated by the chemoreceptors. The influence of the chemoreceptors is most marked in the peripheral beds, where it shifts the whole response curve of the mechanoreceptor control loop upward. This response accounts for most of the upward shift of the pressure response curve. On the other hand, the mechanoreceptor loop affects the ventilation, but this effect is range dependent, being most marked for the low pressure perfusion of the carotid sinus.
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Emphasizing the over-all performance of the O(2) transport system, as well as the interactions between its various subsystems, a method for a parametric performance analysis has been developed. The purpose of such an analysis is three-fold: 1. It permits an evaluation of those parameters which are critical for the performance of the system under conditions of stress. 2. It leads to an assessment of the ranking of individual members within the hierarchy of biological control systems. 3. It permits an objective assessment of the severity and prognosis of cardiovascular and respiratory diseases and of the degree of disability resulting therefrom. Starting with the principle of conservation of mass, two equations are derived which express the balance of oxygen in terms of supply, consumption, and waste. These equations are then developed in terms of the parameters of the system; namely, ventilation, inspired O(2) concentration, cardiac output, O(2) capacity of the blood, energy requirements of the two pumps, fractional extraction of O(2) from alveolar air (ventilation-perfusion ratio), and the oxygen utilization fraction in the periphery. The results indicate that the normal system attempts to maximize the oxygen utilization fraction while minimizing ventilatory and cardiac energy requirements. Changes in the ventilation-perfusion ratio are relatively less important. Possible extensions of the model are discussed.
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