PubMed Health⌕ Search

Biomedical subjects

T Kenner

Publications and source records attributed to T Kenner.

At least 73 records · Page 4Linked to original sources
PubMed1982

Physiological and clinical aspects of respiration control in infants with relation to the sudden infant death syndrome.

We have examined the behavior of several variables which are related to respiratory control in 114 infants (up to 6 months of age) in order to assess the risk for the sudden infant death syndrome (SIDS), 23 of the infants had already had demonstratable serious or life threatening apneas or respiratory problems during surgical anesthesia. These infants were assigned as a risk group, and the rest of the investigated babies was taken as a control group. We found that practically all infants of the risk group had apneas during sleep, which lasted longer than 8 s each. Only 22% of the infants of the control group had apneas of such a duration. As a statistical parameter, calculated from at least 1 hour recording of respiration, we defined the mean apnea duration (MA-value) as average value of apnea duration time in seconds per minute of recording. The MA-value proved to be significantly elevated in the infants of the risk group. The trend to hypoxia in the infants of the risk group was also indicated by the observation of lower transcutaneous PO2-values (tc-PO2) during sleep, when compared with control infants. In agreement with this observation is the increase of the 2,3-DPG concentration and the decrease of the density of erythrocytes of the infants of the risk group. Breathing hypoxic gas mixtures tended to depress respiration in all infants tested, and, especially in the risk group, to elicit irregular respiratory patterns. On the other hand, we observed that inhalation of pure oxygen markedly stimulated respiration in all infants investigated. We conclude from these observations that a risk for SIDS may be related to a particular response pattern of the respiratory center during the early postnatal life. We are able to distinguish infants with a higher risk for SIDS from other children by determination of the MA-value during sleep.

Aminophylline↗
PubMed1982

Physiological measurement in circulation research. A review on the biological application of a new method.

We have recently introduced a new technique for the continuous recording of blood density based on the so-called mechanical oscillator principle. The availability of this technique makes a discussion of the diagnostic meaning of the blood density--defined as mass per unit volume--and its variations under certain conditions worthwhile. In this study, the use of the density dilution method for the determination of distribution volumes of different injected solutions will be discussed. The influence of temperature and of certain artifacts like acceleration forces in the density measuring device has to be considered and may be used for certain additional diagnostic purposes, like the determination of erythrocyte sedimentation velocity. Some most interesting observations are related to the marked influence that fluid shift between extravascular compartments and the intravascular compartment has on blood density. Here, particularly, the effect of the intravenous injection of hypertonic solutions will be discussed. These injections lead to an osmotic fluid shift towards the blood which, in a very characteristic way, reduces blood density and plasma density. A simple model for the description of this reaction is presented. Furthermore, reactions of the blood density to hemorrhage, to different vasoactive substances, and to orthostatic load will be discussed.

Blood Circulation↗
PubMed1980

[Paradoxical ventilatory response of babies to pure oxygen (author's transl)].

In order to determine indicators for the risk of SIDS (sudden infant death syndrome) the respiratory responses of babies (age 1 to 5 months) during sleep to various gas mixtures was examined. Using a face mask combined with a pneumotachograph in all cases a marked increase of the ventilation was found, when the babies were exposed to pure oxygen. Furthermore, the response of the babies to the exposure to mild hypoxia was tested. In 24 out of 36 babies a ventilatory depression was observed which sometimes was coupled with periodic or arrhythmic ventilation. These paradox reactions--depression by mild hypoxia and stimulation by hyperoxia--might be related to a possible circulus vitiosus in the pathogenesis of SIDS.

Carbon Dioxide↗
PubMed1980

[Erythrocyte density distribution disorders in infants with respiratory regulation disorders].

The frequency distribution of the density of erythrocytes was investigated in 22 babies by using the method of Danon and Marikovsky. This investigation seems to be a very suitable method for identifying minimal alterations in the oxygen transport system. In all 22 babies typical S-like density distribution curves were observed similar to those of adults. Eight of the babies with clinically demonstrable disorders in respiration control (ARS) were taken as one group. In comparison with the control group (14 babies) it could be shown that the erythrocytes of the ARS-babies had a lower density than the erythrocytes of normal babies. This difference proved to be statistically significant. No difference between control group and ARS-group could be shown with respect to the distribution of size of the erythrocytes, the mean cell hemoglobin concentration (MCHC), and the mean cell volume (MCV). We assume that the deviation in density distribution of erythrocytes from normal in the ARS-group may be attributed to biochemical changes provoked by the chronical hypoxia. It can be stated that, independent of the interpretation of this phenomenon, a new additional factor could be found for the identification of risks for ARS and possibly for the sudden infant death syndrome (SIDS).

Apnea↗
PubMed1980

[Measurement of the colloid osmotic pressure from plasma density by means of the mechanical oscillator technique (author's transl)].

The colloid osmotic pressure of plasma is a clinically and physiologically important variable. Like the plasma density, it is a function of the total concentration of plasma proteins. Thus, plasma colloid osmotic pressure can be determined from measurement of the plasma density. Minor variations are caused by variations of the albumin-globulin ratio and, much less frequently, by increased concentration of low molecular substances in the plasma. The direct measurement of the colloid osmotic pressure is a time consuming and complex procedure. The determination of the plasma density using the mechanical oscillator technique is a simple and fast procedure. From our results we were able to derive and prove the applicability of an equation which permits the calculation of the colloid osmotic pressure from the measured values of the plasma density. The plasma volume needed for the measurement is 0.2 ml, the measuring time amounts to a few seconds.

Blood Proteins↗
PubMed1979

[Continuous determination of the blood density during haemodialysis (author's transl)].

Application of the mechanical oscillator technique for measurement of blood density, in combination with a reference method for the determination of the absolute value of the blood volume, enables precise and continuous monitoring of fluid shifts during haemodialysis. The significant correlation between blood volume and density or plasma volume and density allows each variation in blood volume to be calculated from the blood density and the slope of the regression line for each individual patient. The possibility of taking continuous measurements and the high accuracy of the mechanical oscillator technique commends this method for the measurement of short-term and small fluid shifts.

Blood Pressure↗
PubMed1979

[Application of the mechanical oscillator technique for the measurement of blood density and hematocrit (author's transl)].

Density measurements were performed with an accuracy of 0.01 g/l by means of a density meter based on the "mechanical oscillator technique", on human whole blood, on plasma, and on erythrocyte concentrates. A highly significant correlation between blood density and hematocrit was found. If plasma and red cell densities are known, hematocrit can be estimated more precisely than using the centrifugation method. This fact is important if small variations of the hematocrit are to be determined. Such variations can be produced, e.g., by alteration of the transcapillary filtration equilibrium. Furthermore, the statistical distribution of plasma and erythrocyte densities allows to determine the range of variation of blood densities for certain hematocrit values and vice versa.

Blood↗