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Biomedical subjects

S Hunter

Publications and source records attributed to S Hunter.

At least 163 records · Page 9Linked to original sources
PubMed1989

Maternal hemodynamics after normal delivery and delivery complicated by postpartum hemorrhage.

Serial hemodynamic investigations were performed in 40 women at 38 weeks' gestation and then 1, 2, 6, 10, and 14 days after normal delivery. Cardiac output was measured by Doppler and cross-sectional echocardiography at the aortic valve. In 30 controls who received an average of 280 mL intravenous fluid during labor, the mean cardiac output remained elevated (7.15 L/minute) for 24 hours after delivery and then fell to 5.39 L/minute at 10 days as a result of decreases in both heart rate and stroke volume. Blood pressure fell during the first 2 days after delivery and thereafter increased to values not significantly different from those recorded at the end of pregnancy. In ten women who experienced postpartum hemorrhage, stroke volume decreased and heart rate increased, relative to the control group, during the first 48 hours after delivery. Blood pressure and cardiac output, however, were not significantly different from values in the control group.

Adult↗
PubMed1988

The role of the priming fluid in the metabolic response to cardiopulmonary bypass in children of less than 15 kg body weight undergoing open-heart surgery.

The major metabolic response to open-heart surgery using cardiopulmonary bypass has been shown in adults to be modified by the components of the pump priming fluid. This effect is likely to be more significant in children. Data on 29 children less than 15 kg body weight are presented. Patients were randomised to receive a prime containing one of three crystalloid priming fluids: 100% Hartmann's (H), 50% Hartmann's + 50% 5%-Dextrose (HD), or 100% Plasmalyte 148 (P). The remainder of the prime was CPD stored blood and the prime was buffered with sodium bicarbonate. Severe hyperglycaemia 22.4 +/- 1.3 mmol/l occurred during bypass in the HD group but moderate hyperglycaemia occurred in the other prime groups. Hyperlactataemia occurred in all prime groups during bypass and was highest in the H prime group at 3.9 +/- 0.4 mmol/l. These changes in intermediary metabolites were only partly explained by the crystalloid components of the priming fluid. A subsiduary study revealed the important contribution of CPD stored blood to those intermediary metabolite concentrations. Therefore, the well recognised changes in intermediary metabolites as components of the metabolic response to surgery, namely hyperglycaemia and hyperlactataemia were augmented by the composition of the priming fluids. In addition, CPD stored blood and the sodium bicarbonate buffer increased the sodium concentration of the prime to hypernatraemic levels in both the H and P groups which caused an increase in sodium concentration during bypass. Therefore important changes during bypass occur as a direct result of the individual components of the priming fluid. These changes may result in osmolal flux, hyperglycaemia and hyperlactataemia, all of which have been reported to be potentially harmful.

Blood Glucose↗
PubMed1988

Doppler echocardiographic estimation of cardiac output: analysis of temporal variability.

The temporal variability of combined cross-sectional and Doppler echocardiographic estimates of cardiac output was studied in 14 normal subjects. In each subject cross-sectional echocardiographs and Doppler velocities were recorded from the aortic, pulmonary and mitral valves. Recordings were repeated after 30-60 min and after 1-3 months to allow estimation of short-term and long-term temporal variability. A components of variance analysis showed that between-subject variability was significantly larger than within-subject variability for all measured and calculated variables. Long-term variability was larger than short-term variability for all variables except the mitral valve area. Calculation of flows from the three measurement sites were equally reproducible and the mean percentage error for CO measurements performed 1-3 months apart ranged from 6.4% to 7.4%. The 95% confidence intervals for Doppler measurements of CO at the three sites ranged from +/- 0.49 l min-1 to +/- 0.56 l min-1, suggesting that the temporal variability of flow measurements using the non-invasive Doppler method is sufficiently small for the method to be useful in serial haemodynamic studies.

Adult↗
PubMed1988

Reproducibility of cardiac output measurement by cross sectional and Doppler echocardiography.

The variability of Doppler echocardiographic estimation of cardiac output at the aortic orifice was investigated in eight healthy subjects. Cross sectional echocardiograms of the aortic orifice and aortic Doppler velocities were recorded and measured by four echocardiographers. Between subject variability was significantly larger than within subject variability for all variables. Variability owing to different echocardiographers and different measurement times was small compared with total variability. Coefficients of variation for aortic annular diameter, aortic velocity integral, and heart rate were 4.1%, 6.4%, and 5.0% respectively. The coefficient of variation for cardiac output was 8.8% and the 95% confidence interval for measurement of cardiac output by the Doppler method was 4.45 to 6.35 l/min. One echocardiographer reanalysed all the recordings and the results showed that recording the echocardiograms introduces a significantly larger source of error than measuring them. Thus serial measurements of cardiac output by the Doppler method can be performed with acceptable reproducibility; this indicates that the technique can be accurately applied in clinical practice.

Adult↗
PubMed1987

Cardiac output during labour.

Serial measurements of cardiac output and mean arterial pressure were performed in 15 women during the first stage of labour and at one and 24 hours after delivery. Cardiac output was measured by Doppler and cross sectional echocardiography at the pulmonary valve. Basal cardiac output (between uterine contractions) increased from a prelabour mean of 6.99 l/min to 7.88 l/min at greater than or equal to 8 cm of cervical dilatation as a result of an increase in stroke volume. Over the same period basal mean arterial pressure also increased. During uterine contractions there was a further increase in cardiac output as a result of increases in both stroke volume and heart rate. The increment in cardiac output during contractions became progressively greater as labour advanced. At greater than or equal to 8 cm of dilatation cardiac output increased from a basal mean of 7.88 l/min to 10.57 l/min during contractions. There were also further increases in mean blood pressure during contractions. One hour after delivery heart rate and cardiac output had returned to prelabour values, though mean arterial pressure and stroke volume remained raised. By 24 hours after delivery all haemodynamic variables had returned to prelabour values. Haemodynamic changes of the magnitude found in this series are of considerable clinical relevance in managing mothers with complicated cardiovascular function.

Adult↗
PubMed1987

Cytoplasmic androgen binding protein of rat liver: molecular characterization after photoaffinity labeling and functional correlation with the age-dependent synthesis of alpha 2u-globulin.

The liver of the mature male rat contains a moderate affinity (Kd = 10(-8)M), low-capacity, cytoplasmic androgen binding protein (CAB) whose appearance during puberty and disappearance during senescence correlate with the androgen-dependent synthesis of alpha 2u-globulin. Molecular properties of CAB were examined by photoaffinity labeling with tritiated methyltrienolone (R-1881), a synthetic androgen, and by its localization within the hepatocytes which are competent to produce alpha 2u-globulin. Photoaffinity labeling of the liver cytosol derived from postpubertal male rats, followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography, showed a predominant androgen binding band corresponding to Mr 31,000. This 31-kilodalton (kDa) binding component was conspicuously absent in the liver of androgen-insensitive prepubertal and senescent male rats and in adult male rats treated with estradiol-17 beta. In addition, unlike the cytoplasmic extract, the nuclear lysate of the male rat hepatocytes did not contain the 31-kDa androgen binder. Disappearance of the 31-kDa androgen binding band from the cytosolic fraction of androgen-insensitive animals was associated with a concomitant appearance of a minor androgen binding component of apparent Mr 29,000. The livers of postpubertal male rats normally contain two subpopulations of hepatocytes, only one of which is highly active (competent) in alpha 2u-globulin synthesis. Separation of these two subpopulations through a fluorescence-activated cell sorter followed by whole cell labeling showed more than a 2-fold higher uptake of R-1881 by the competent cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Affinity Labels↗
PubMed1987

Combined Doppler and echocardiographic measurement of cardiac output: theory and application in pregnancy.

A non-invasive technique for the measurement of cardiac output in pregnancy by combined cross-sectional and Doppler echocardiography at three intracardiac sites is described. The validity of the technique for use during pregnancy is reviewed. Comparison with cardiac output determined simultaneously by the direct Fick technique in 15 non-pregnant subjects showed close agreement for all three measurement sites. Acceptable measurements were obtained from the aortic and pulmonary valves in all pregnant subjects and from the mitral valve in 84% of pregnant subjects. The within-patient intra-observer and hour-to-hour variabilities of cardiac output in pregnant and non-pregnant subjects were less than 5% of the mean for all three valves studied. Flow measurements at each of the three intracardiac sites correlated closely. The advantages and limitations of the technique for use during pregnancy are discussed.

Adolescent↗
PubMed1987

Haemodynamic changes during the puerperium: a Doppler and M-mode echocardiographic study.

Serial haemodynamic investigations were performed in 15 women at 38 weeks gestation and then 2, 6, 12 and 24 weeks after delivery. Cardiac output was measured by Doppler and cross-sectional echocardiography at the aortic, pulmonary and mitral valves. Cardiac chamber size and ventricular function were investigated by M-mode echocardiography. Flow measurements at the three intracardiac sites correlated closely. Cardiac output fell from a mean of 7.42 l/min at 38 weeks to 4.96 l/min at 24 weeks after delivery, a fall of 33%. Most of this decrease (28%) had occurred by 2 weeks. This was associated with a 20% reduction in heart rate and an 18% reduction in stroke volume. By 2 weeks after delivery there was a significant decrease in left atrial dimension and left ventricular end-diastolic dimension. Left ventricular wall thickness and mass declined throughout the period of study as did aortic, pulmonary and mitral valve areas. M-mode derived indices of myocardial contractility were all significantly reduced by 2 weeks and thereafter showed no further change. No haemodynamic differences were found between lactating and non-lactating mothers.

Adult↗
PubMed1987

Balloon dilatation of unoperated aortic coarctation: immediate results and one year follow up.

Fifteen patients aged 1-19 years (mean 10.9) with previously unoperated aortic coarctation underwent percutaneous balloon angioplasty between January 1985 and February 1986. Nine (60%) were hypertensive at presentation. Under general anaesthetic the systolic coarctation gradient was 24-50 mm Hg (mean 29) and the coarctation diameter was 4-9 mm (mean 5.5). Meditech balloon catheters 8-18 mm in diameter were inflated 1-4 times at 410-760 kPa. After dilatation the systolic coarctation gradient decreased to 0-20 mm Hg (mean 6) and the coarctation diameter increased to 7-20 mm (mean 12). One patient developed a fusiform aneurysm of the aorta at the coarctation site immediately after the procedure. At reinvestigation 6-16 months (mean 12.5) after dilatation 14 of the 15 patients were normotensive. In 13 patients the residual coarctation gradient was 0-10 mm Hg (mean 3). Two patients had recoarctation with residual gradients of 20 and 24 mm Hg and underwent successful repeat dilatation. One patient had developed a small discrete aneurysm at the coarctation site. Balloon angioplasty is thus a safe and effective method of relieving unoperated aortic coarctation. The frequency of aortic aneurysm and recoarctation is small and probably related to balloon size. This early experience is encouraging, but long term results and further experience are required before this approach is used to treat coarctation generally.

Adolescent↗
PubMed1987

The empty delta sign: frequency and significance in 76 cases of dural sinus thrombosis.

The presence of the empty delta sign on contrast material-enhanced computed tomographic (CT) scans of the brain is considered pathognomonic of sagittal sinus thrombosis (SST); however, a valid explanation for its appearance is lacking, despite several hypotheses. To determine the frequency of the sign and its prognostic significance, 76 reported cases (112 CT manifestations) of SST and SST-related intracranial sinovenous occlusive disease were reviewed. Ten CT signs related to both disease processes were reported; the empty delta sign was the most frequently reported sign (28.6%) of SST. Patients with hemorrhagic infarction and/or the empty delta sign on CT scans had the poorest prognosis. A case illustrative of the empty delta sign is described in which there was engorgement of endothelial- and nonendothelial-lined spaces in the dura mater with hemorrhagic rupture into the dural leaf. The empty delta sign can probably be explained on the basis of the rich dural venous collateral circulation, consisting primarily of lateral lacunae, a vascular mesh (dural cavernous spaces), and meningeal venous tributaries.

Adult↗