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Biomedical subjects

N Evans

Publications and source records attributed to N Evans.

At least 109 records · Page 6Linked to original sources
PubMed1994

Smoking initiation rates in adults and minors: United States, 1944-1988.

To the authors' knowledge, calendar year trends in cigarette smoking initiation rates have not been examined on a population basis. National Health Interview Survey data (1970, 1978, 1979, 1980, 1987, and 1988) on age of starting to smoke fairly regularly were used to compute smoking initiation rates for males and females aged 10-24 years from 1944 through the mid-1980s. Information from 102,626 respondents was included. The authors examined trends in these rates and looked for associations with milestones in the antismoking public health campaign. Smoking initiation in 21- to 24-year-old (adult) males declined sharply beginning around 1950 when evidence regarding the health consequences of smoking was first made public. The decline in adult females began in the mid-1960s when the Surgeon General's report was released, intensifying the public health campaign. The initiation rate for adult males and females dropped below 1% by the end of the study period. Initiation rates in 15- to 20-year-old males also began to decrease in the mid-1960s, but rates for 10- to 14-year-old males did not decrease over the study period. Initiation rates for females both in the 15-20 and 10-14 year age groups actually increased, at least through the mid-1970s. These trends in smoking initiation suggest that knowing the health consequences of smoking has kept adults from starting to smoke. Such knowledge either may be lacking or may not be salient among the youngest age groups.

Adolescent↗
PubMed1994

Assessment of ductus arteriosus shunt in preterm infants supported by mechanical ventilation: effect of interatrial shunting.

We studied 51 preterm infants (< 1500 gm) with serial color Doppler echocardiography to determine the impact of incompetence of the foramen ovale on the hemodynamic implications of shunting through a patent ductus arteriosus. Doppler and two-dimensional echocardiographic measures included left atrial/aortic root ratio, right (RVSV) and left ventricular stroke volumes (LVSV), and outputs to determine relative ventricular outputs (RVSV/LVSV) and to calculate the pulmonary/systemic flow ratio (Qp/Qs), the diameter of the color flow Doppler mapping of interatrial and ductal shunts, pulsed Doppler pattern, and velocity of those shunts. The dominant direction of shunting at the ductal and atrial levels was left to right. In studies with minimal atrial shunting, there was a weak but significant correlation between RVSV/LVSV (1/(Qp/Qs)) and the left atrial/aortic root ratio, LVSV, and output index, but there was a close correlation with the diameter of the color flow Doppler of the shunt within the ductus (r = -0.8). With this diameter used as a constant, increasing color flow Doppler diameter of atrial shunt significantly reduced LVSV and increased RVSV/LVSV (1/(Qp/QS)). In infants with large ductal and atrial shunts, right ventricular output was often greater than left ventricular output. We conclude that atrial shunting has a significant impact on the hemodynamic implications of ductal shunting in many very preterm infants. This renders use of the relative ventricular outputs to calculate Qp/Qs inaccurate as a single measure of shunt size in patent ductus arteriosus. If the shunt is predominantly left to right, the most accurate assessment is provided by color flow ductal shunt diameter.

Atrial Function, Left↗
PubMed1994

Incompetence of the foramen ovale in preterm infants supported by mechanical ventilation.

Fifty-one preterm infants (< 1500 gm) who were supported by mechanical ventilation were studied by use of serial color Doppler echocardiography to determine the hemodynamic impact of incompetence of the foramen ovale. Right and left ventricular stroke volume, measured by two-dimensional and Doppler echocardiography, were used to determine the ratio of pulmonary to systemic flow (Qp/Qs). The diameter of the color flow mapping of any interatrial shunt was measured together with pattern and velocity of that shunt. Ductal patency status was established. Most infants had some atrial shunting. The dominant direction of shunting was left to right within a bidirectional shunt pattern (75%). When the ductus was closed, there was a significant correlation between color Doppler diameter of the atrial shunt and Qp/Qs (r = 0.71). When this diameter was less than 2 mm, there was minimal impact on Qp/Qs. Measurable effects on Qp/Qs were usually seen at diameters > 3 mm when Qp/Qs ratios of up to 2:1 were recorded. Longitudinally, atrial shunting could be divided into four groups. Group 1 (n = 23) had minimal shunt or small shunts (< 3 mm) that resolved early, group 2 (n = 11) had small shunts that persisted, group 3 (n = 9) had large shunts (> 3 mm) that resolved, and group 4 (n = 6) had large shunts that persisted. Clinically there were no significant differences between the groups except that patients in groups 2 to 4 tended to having worse acute lung disease than patients in group 1 and had significantly more chronic lung disease. We conclude that many preterm infants have left-to-right atrial shunts that have a noninvasively measurable hemodynamic impact. This may have an effect on acute and chronic respiratory outcome and is likely to affect assessments of ductal shunting.

Atrial Function, Left↗
PubMed1994

A blinded comparison of clinical and echocardiographic evaluation of the preterm infant for patent ductus arteriosus.

The accuracy of the characteristic physical signs of a patent ductus arteriosus (PDA), that is, a systolic murmur, increased volume of pulses and increased praecordial activity, in diagnosing a haemodynamically significant PDA in ventilated premature infants was prospectively evaluated. Fifty-five ventilated preterm infants (birthweight < 1500 g) had daily echocardiographic and clinical evaluation for a PDA for the first 7 days of life. The examiners were blinded to each other's findings. Probability analysis was performed for the accuracy of each clinical sign in detecting a haemodynamically significant PDA as defined by echocardiographic criteria. Clinical signs were poor at detecting a significant PDA in the first 4 days of life. On day 1, none of the 10 infants with a significant PDA had a murmur. By day 4, clinical signs were better at detecting a significant PDA, but specificity remained poor with many false positive signs. Six infants had murmurs with a closed duct. The development of echocardiographic haemodynamic significance preceded the development of physical signs by a mean of 1.8 days. Significant ductal shunts often occurred silently, but the development of a murmur often marked an increase in the velocity of the flow through the duct rather than an increase in the size of a shunt. This study confirms that echocardiography is required for the reliable early diagnosis of a PDA in ventilated preterm infants.

Ductus Arteriosus, Patent↗
PubMed1994

Cardiovascular effects of dexamethasone in the preterm infant.

Twenty preterm infants were studied serially with Doppler echocardiography to document changes in pulmonary artery pressure, myocardial thickness, and patent ductus arteriosus associated with dexamethasone treatment for chronic lung disease. Pulmonary artery pressure was assessed with Doppler, by its inverse correlation with the ratio of the pulmonary artery time to peak velocity (TPV) and right ventricular ejection time (RVET). Eleven of the 20 infants showed an increase in TPV/RVET after commencing steroids, suggesting a fall in pulmonary artery pressure. This change was not sustained in most cases and had no correlation with the improvement in respiratory status. Ventricular septal and left ventricular posterior wall thickness increased in all 11 infants in whom it was measured. The median increase was respectively 0.9 and 0.8 mm. In most infants this increase was small, less than 1 mm, however two infants developed marked septal hypertrophy with Doppler evidence of left ventricular outflow tract obstruction. Dexamethasone had no consistent closing effect on a patent ductus arteriosus in four infants. Myocardial hypertrophy occurs in most infants, in some it is severe. It would seem prudent to monitor echocardiographically for this side effect.

Blood Pressure↗
PubMed1994

Re-evaluation of the left atrial to aortic root ratio as a marker of patent ductus arteriosus.

The aim of this study was to re-examine the accuracy of the left atrial aortic root ratio (LA:Ao) as a marker of significant patent ductus arteriosus (PDA) in the preterm infant by comparison with direct Doppler echocardiographic assessment. Fifty six infants (< 1500 g) had 463 serial echocardiograms. Firstly the LA:Ao was measured, then the duct was imaged and classified as wide open, restricting, or closed according to two dimensional and Doppler criteria. Probability analysis was performed to test the ability of the LA:Ao to discriminate between a wide open PDA and a restricting or closed duct. Mean LA:Ao was 1.17 and 1.21 when the duct was respectively closed or restricting compared with 1.61 when wide open. Using a LA:Ao of 1.5 as a cut off gives a sensitivity of 79% and specificity of 95% and increases the accuracy over the recommended levels of 1.3 and 1.4. With this cut off there were 20/94 false negatives, these were associated with scans on day 1 and large interatrial shunts. The sensitivity of the LA:Ao increased to 88% if only scans performed after day 1 were analysed. For diagnosing a PDA after day 1, the positive likelihood ratio of an LA:Ao of 1.5 or more was 17.5, and the negative likelihood ratio of an LA:Ao < 1.5 was 0.13. The LA:Ao is still a useful tool in the diagnosis of PDA. It is a simple method which needs less skill and resources than direct PDA imaging and is feasible on neonatal units without direct access to echocardiographic expertise. Its use on the first postnatal day is not recommended.

Anthropometry↗
PubMed1994

Subclinical persisting pulmonary hypertension in chronic neonatal lung disease.

The development of pulmonary hypertension is one of the adverse factors in the outcome of infants with chronic neonatal lung disese (CNLD). The purpose of this cross sectional study was to evaluate the prevalence and degree of pulmonary hypertension in a cohort of survivors of CNLD stable in air. Pulmonary artery pressure was assessed using its inverse correlation with the ratio of time to peak velocity and right ventricular ejection time (TPV:RVET) as measured from Doppler velocity time signals in the main pulmonary artery. A normal ratio is > or = 0.35, a possibly low ratio lies between 0.31 and 0.35, and a definitely low ratio is < 0.31. The subjects were divided into three groups. Group A comprised 58 infants with oxygen dependence and an abnormal chest radiograph at 28 days of age; group B comprised 18 infants with oxygen dependence and a normal chest radiograph at 28 days of age; and group C (controls) comprised 21 siblings without oxygen dependence by 10 days and a normal chest radiograph. There were significant differences in mean (SD) TPV:RVET ratio between group A 0.346 (0.045), group B 0.335 (0.057), and groups A + B 0.344 (0.048) when compared with group C controls 0.385 (0.034). The prevalence of a definitely low TPV:RVET ratio suggesting a raised pulmonary artery pressure was 19% in group A, 39% in group B, 24% in groups A + B, and none in group C. There were no clinical signs of pulmonary hypertension in any patient studied. Stepwise multiple linear regression failed to find significant associations with antenatal or neonatal putative risk factors. Additionally, there were no associations with childhood respiratory morbidity. These data suggest a high prevalence of subclinical pulmonary hypertension in CNLD patients. It is speculated that occult hypoxaemia may be occurring in this group of infants.

Age Factors↗
PubMed1993

Liver disease in association with neonatal lupus erythematosus.

This report describes a patient with neonatal lupus erythematosus (NLE) in whom there was multisystem involvement including neonatal hepatitis. The hepatitis, defined pathologically as a giant cell hepatitis, presented with severe cholestasis, was unrelated to other known causes of neonatal hepatitis and resolved spontaneously by 6 months of age. Both mother and infant were positive for Sjögren syndrome A+B antibodies (SS-A[Ro] and SS-B[La]) as well as having high titres of antinuclear antibody (ANA). Three of the four cases described in the one previous report of this association were also ANA positive. This antibody may be a marker for the development of the hepatitis. Maternal and infant ANA status should be determined in cases labelled as idiopathic neonatal hepatitis to exclude undiagnosed maternal SLE as a cause of neonatal cholestasis.

Adult↗
PubMed1993

Anorectal function of children with neurological problems. I: Spina bifida.

Anorectal function was assessed with anorectal manometry in 45 children with spina bifida (21 girls and 24 boys, mean age 11 1/2 years). 24 enuretic children served as controls. The pressure in the first and second centimeters of the anal canal was lower among index children than controls and also lower among those with high spinal lesions compared with those with low lesions. Rectal activity (rectal sensation and trace appearance) during rectal distension appeared to be reduced among index children; sensation was particularly poor among those with high spinal lesions. Manometry may be useful in children with spina bifida as it provides a clearer understanding of sphincter function and leads to a more rational approach to the management of bowel problems.

Adolescent↗
PubMed1993

Change in blood pressure after treatment of patent ductus arteriosus with indomethacin.

The effect of indomethacin treatment of patent ductus arteriosus (PDA) on blood pressure was studied in 24 preterm infants. PDA was diagnosed clinically and confirmed by echocardiography; the effect of treatment was monitored echocardiographically. Hourly intra-arterial recordings of systolic, diastolic, and mean blood pressure were averaged for the 48 hours before the first dose of indomethacin and for each of the three 24 hour periods after the first dose. In the 16 infants in whom treatment was successful, the average mean blood pressure increased significantly over the three days after the first dose. On the third day after beginning treatment with indomethacin the average increase in mean blood pressure was 10.4 mm Hg. Fourteen of 16 infants showed an increase of 4 mm Hg or more. Systolic and diastolic blood pressure increased significantly by similar amounts, so the pulse pressure did not change. In the eight infants treated unsuccessfully, there was no consistent change in any of the blood pressure parameters. The maximum increase in mean blood pressure was 3 mm Hg. These findings confirm that PDA is one of the determinants of blood pressure in preterm infants. The effect is general and there is no consistent change in pulse pressure when a PDA is closed. A general increase in blood pressure is a useful additional indicator of successful medical ductal closure.

Blood Pressure↗
PubMed1993

Anorectal function of children with neurological problems. II: cerebral palsy.

In response to the frequent complaint of difficulties with defecation experienced by children with cerebral palsy, 34 children (13 girls and 21 boys, mean age 10 years) with cerebral palsy were investigated by questionnaire and anorectal manometry. 24 enuretic children served as controls for the anorectal manometry. Constipation affected 26 of 29, defecation distress eight and faecal incontinence 16 of the index children, but incontinence was mild in most cases. Index children had a low resting pressure in the first centimetre of the anal canal, slow anal rhythmical activity and a pressure increase in the first centimetre during maximum rectal distension. These findings suggest anal sphincter and/or pelvic floor muscle incoordination, but no evidence of abnormal rectal function. The authors conclude that surgical intervention was not indicated for the index children, but that medical treatment could be improved.

Adolescent↗
PubMed1992

Racial differences in the anatomical distribution of colon cancer.

The objective of this study was to determine whether racial differences exist with regard to the anatomical distribution of adenocarcinoma of the colon. We conducted a retrospective study of consecutive patients with primary colon cancer seen during a 12-year period (1976 to 1987) identified by the Rush Tumor Registry. The setting was a large, tertiary-care, private medical center, located in the inner city of Chicago, Ill. A chi 2 unpaired Student's t test of association was performed to detect any statistically significant difference in the anatomical sites of distribution between blacks and whites. A statistically significant percentage of black patients had proximally located primary colon lesions compared with white patients. This observation was independent of the actual anatomical definition of right-sided or proximal colon lesions. These findings suggest that a significant percentage of black and white patients are less likely to be diagnosed with colon cancer at a more curable stage, when abiding by the current screening guidelines of the American Cancer Society and the National Cancer Institute. The impact is greater on black patients with adenocarcinoma of the colon.

Adenocarcinoma↗