PubMed Health⌕ Search

Biomedical subjects

G Gennser

Publications and source records attributed to G Gennser.

At least 19 recordsLinked to original sources
PubMed1991

Aortic diameter pulse waves and blood flow velocity in the small, for gestational age, fetus.

An ultrasound phase-locked, echo-tracking system was used for noninvasive measurements of pulsatile diameter changes in the descending aorta of 60 small, for gestational age (SGA), fetuses and of 60 fetuses appropriate for gestational age (AGA). Pulsed Doppler ultrasound was used for the recording of blood flow velocity in the aorta and in the umbilical artery of the SGA fetuses. In the SGA fetuses, a weight-related higher end-diastolic diameter and a lower relative pulse amplitude suggest that diastolic blood pressure was increased; a less steep rise of the initial ascending part of the pulse wave and a lower relative pulse amplitude suggest that the absolute stroke volume was decreased. Except for a positive correlation between relative pulse amplitude and mean velocity in the aorta, no correlation was found between diameter pulse waves and blood flow velocity. Aortic diameter pulse waves apparently yield no unequivocal information as to peripheral resistance, for which purpose blood flow velocity waveform analysis would seem, at least at present, to be the only available method.

Adult↗
PubMed1990

Blood flow velocity and pulsatile diameter changes in the fetal descending aorta: a longitudinal study.

Blood flow velocity and pulsatile diameter changes in the fetal descending aorta were measured subsequently with pulsed Doppler ultrasonography and phase-locked echo-tracking technique, respectively. Blood flow velocity and pulse-wave curves with equal beat-to-beat intervals were synchronized by external fetal electrocardiogram. The systolic increase in blood flow velocity and in vessel diameter started simultaneously. The velocity peak preceded the diameter peak by a significant margin (p in the range 0.0001 to 0.0014). The time interval was more pronounced in the thoracic than in the abdominal part of the aorta and was slightly smaller near term. The effective diameter, calculated from the synchronized integrals of the blood flow velocity and the diameter curves, was significantly greater (p in the range 0.0001 to 0.0016) than the mean diameter. The difference tended to decrease with advancing gestational age and was more pronounced in the thoracic than in the abdominal aorta. The maximum error incurred by the use of nonsimultaneous measurements of blood flow velocity and vessel diameter when calculating volume blood flow was found to be less than 8% and thus probably of little practical importance.

Aorta, Thoracic↗
PubMed1989

Derivation of haemodynamic information from ultrasonic recordings of aortic diameter changes.

An ultrasound phase-locked echo-tracking system was used for noninvasive measurements of diameter changes in the upper abdominal aorta of the anaesthetised cat. Comparisons were made between the noninvasively recorded diameter changes and central haemodynamic variables measured with inserted catheters and transducers. It was found that noninvasive observations of aortic diameter changes give reliable information on the direction and relative magnitude of the blood pressure change both in systole and in diastole. Indications of the direction of change of stroke volume, cardiac output, and aortic flow acceleration (a measure of cardiac inotropy) could also be gained. The information, taken together, comprises a pattern of response reflecting cardiovascular adjustments likely to have occurred. It is suggested that the technique is suitable for interpretation of (patho-) physiological changes in the foetus, as well as for determinations of great vessel compliance in man, i.e., in atherosclerosis research.

Animals↗
PubMed1988

Low birth weight and risk of high blood pressure in adulthood.

Hospital birth records were sought for 104 men from a pool of male army conscripts with "normal" or "high" blood pressure when measured at 28 years of age. Of 77 men whose birth weight and date of the mother's last menstrual period before the pregnancy could be found, 25 had a resting diastolic blood pressure of greater than or equal to 90 mm Hg. In 11 of these compared with nine of the 52 men with normal diastolic pressures their birth weights in relation to gestational age had been below the mean and 1 SD of a comparable Swedish population. The risk of increased diastolic blood pressure in early adult life was significantly higher among men who had been growth retarded at birth than among those whose birth weight had been appropriate for gestational age (odds ratio 3.63; 95% confidence interval 1.14 to 12.57). Being born small for gestational age may be a predictor of raised blood pressure in early adult life.

Adult↗
PubMed1987

Cardiovascular dynamics in relation to presentation and postural changes in normal fetuses.

The role of fetal cardiovascular function in the reduced intrauterine growth rate of breech pregnancy was studied in fetuses with different presentations. Hemodynamic responses to postural changes were also investigated in fetuses in horizontal and vertical positions. Thirty-one normal pregnancies, with 15 fetuses presenting by the breech and 16 fetuses by the vertex, were included in the study. Diameter pulse waves from the fetal descending aorta were measured using equipment combining real-time ultrasound imaging with phase-locked echo-tracking. No differences in basal pulse wave parameters were demonstrated between breech and vertex fetuses nor did any differences appear when maternal posture was changed from horizontal to upright or vice versa. The present observations suggest that fetal circulatory factors are less likely to be a primary cause of the reduced intrauterine growth in breech presentation. Tilting of the fetus in late gestation seems to produce neither a redistribution of its blood volume nor secondary adaptations to an orthostatic challenge. The hydrostatic effect of amniotic fluid presumably precludes the requirement of fetal circulatory adaptation to postural changes.

Adult↗
PubMed1987

Interdependence of pulse wave variables in the human fetal aorta.

The problem of inferring the state of fetal circulation from diameter pulse waves in the descending aorta was studied with the aid of statistical methods in 12 fetuses in late uncomplicated gestation. By means of a phase-locked, echo-tracking ultrasound technique, aorta diameter-time waveforms and pulse propagation velocities were measured. In a factor analysis, three independent factors explained 75% of the total variance of variables in the waveforms. Relationships between some of the variables and biophysical events are suggested; they await confirmation from animal experiments, in order to develop a practical method for assessing fetal circulation.

Aorta, Thoracic↗
PubMed1986

The effect of carbon dioxide inhalation on phase characteristics of breathing movements in healthy newborn infants.

Chest wall distortion (inward motion of the rib cage on inspiration) has been found recently to reduce the tidal volume during active sleep in the neonatal period. To determine some of the factors that relate to the chest wall distortion and the decreased tidal volume seen in active sleep, a quantification of the phase differences between the movements of the chest wall and those of the abdominal wall, and of the relation of their phase differences to tidal volume was performed on data obtained before and during carbon dioxide stimulation in 15 newborn infants sleeping in the prone position. In quiet sleep, the breathing movements were congruent and regular, and the tidal volume and the mean inspiratory flow increased during carbon dioxide stimulation. In active sleep during exposure to carbon dioxide, the chest wall distortion decreased, the breathing movements were incongruent and the degree of the chest wall distortion was negatively correlated with the tidal volume, while the tidal volume and the mean inspiratory flow was increased. Chest wall distortion did not appear in quiet sleep and was decreased in active sleep in spite of increased ventilation during CO2 stimulation. This study favours the idea that chest wall distortion is caused by a well regulated change in neuromuscular activity and not by the strength of diaphragmatic movements overcoming the mechanical stability of the rib cage.

Abdomen↗
PubMed1986

Incidence and recurrence rate of abruptio placentae in Sweden.

It is desirable to identify those pregnancies that run an increased risk of abruptio placentae, as this disorder still is associated with a high perinatal mortality. Data were collected from the Swedish nationwide birth registry system on all 894,619 births in Sweden in the period 1973 to 1981. The overall incidence of abruptio placentae was 0.44%, with a perinatal mortality of 20.2% and a cesarean section frequency of 74.6%. The incidence of abruptio placentae was significantly increased in the case of twin birth, male offspring, mothers below 20 years of age, and with every delivery after the second one. A history of abruptio placentae increased the risk of a similar incident in a subsequent pregnancy by 10.2-fold. The frequency of cesarean section in subsequent parturitions remained high (32.1%) even in the absence of reabruptio placentae, thus demonstrating the need to identify further risk groups.

Abruptio Placentae↗
PubMed1979

Fetal breathing movements and maternal exercise.

Earlier statements that fetal breathing movements (FBM) are sensitive to changes in the fetal homeostasis prompted the study of the effect of maternal exercise on FBM and fetal heart rate. Forty women in the last trimester of gestation were subjected to a work load (80 W) for 5 min on a bed ergometer cycle; in 30 of them FBM were recorded by A-mode ultrasound, and in 10, the fetal heart rate was monitored by continuous ultrasound. Maternal blood pressure, pulse rate, blood pH and pCO2, and transcutaneous pO2 were also followed. The FBM showed a transient marked increase in incidence immediately after the end of the exercise. No changes in basal level or in baseline variability of the fetal heart rate were found in the recovery period after work. Some possible causes of the observed FBM alterations are discussed. The findings imply that, after this particular form of stress, FBM are a more sensitive indicator of the physiological state of the fetus than the fetal heart rate.

Adult↗
PubMed1979

Effects on fetal breathing movements of maternal challenges. Cross-over study on dynamic work, static work, passive movements, hyperventilation and hyperoxygenation.

Ten women in the last trimester of a normal pregnancy were subjected to five different loads in a cross-over study. Fetal breathing movements (FBM), fetal heart rate (FHR), maternal heart rate (MHR), and mean arterial pressure (MAP), maternal transcutaneously measured pO2 (Tc-pO2), and the energy supply to the Tc-pO2 electrode were recorded continuously before, during, and after the load. Maternal capillary pH and pCO2 were measured at three representative time points. The immediate responses of the incidence of FBM to the different challenges were: increase after dynamic work (bicycle test); no change after static work (isometric muscle contraction) and passive movements; decrease after hyperventilation and hyperoxygenation. FHR was unaffected by all challenges. The FBM incidence varied in parallel with pCO2 after dynamic work and hyperventilation and inversely with the Tc-pO2 rise caused by hyperoxygenation. Maternal pH was increased after passive movements (no change in FBM) and after hyperventilation (decreased incidence of FBM), FBM seem to be more sensitive to environmental changes than is the FHR. Mechanical stimuli to the uterus were not responsible for the augmentation of FMB seen after the bicycle test. The present observations reveal the multifactorial nature of the regulation of FBM, and support the role of CO2 as a major stimulator of breathing movements also in prenatal life.

Adult↗
PubMed1979

On improved outcome of twin pregnancies.

During the past four years, an attempt has been made in Malmö to reduce the frequency of preterm termination of twin pregnancies. For this purpose, the entire pregnant population of this medium-sized city was subjected to general ultrasonic screening in the second trimester. This detected 88 per cent of the twin pregnancies. The screening has a methodological error of 2 per cent. Eightysix of the women with twin pregnancy were subjected to bedrest in hospital for more than two weeks in the second half of gestation. The incidences of twins born with birth weight below 1 500 g and of twins light-for-gestational-age were reduced compared with those a decade earlier. Also the group of twins born before the 37th week decreased, and the perinatal mortality rate fell to the same level as in singleton pregnancies. Early detection of twin pregnancies followed by rest for the pregnant women seems to contribute to an improved outcome of these gestations.

Birth Weight↗