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Biomedical subjects

A B Lewis

Publications and source records attributed to A B Lewis.

At least 19 recordsLinked to original sources
PubMed1992

Left ventricular performance in neonates on extracorporeal membrane oxygenation.

The evaluation of left ventricular systolic performance in infants undergoing extracorporeal membrane oxygenation (ECMO) using traditional ejection-phase indices is hampered by significant alterations in preload and afterload. Therefore, a load-independent index, which relates heart-rate-corrected mean velocity of circumferential fiber shortening (VCFc) to afterload, measured as end-systolic wall stress (ESS), was used to assess left ventricular function in 18 term neonates undergoing ECMO. The mean age at the onset of ECMO was 75.5 h and the duration of therapy was 171 +/- 106 h. Left ventricular performance was highest before the onset of ECMO (VCFc = 1.65 +/- 0.49 circ/s) and decreased toward normal during (1.38 +/- 0.33 circ/s) and following ECMO (1.29 +/- 0.16 circ/s). Initially, nine of 17 (53%) patients had enhanced performance for the degree of afterload but in only 16 of 48 (33%) studies during ECMO and none following ECMO was VCFc elevated beyond the normal range predicted for ESS. These changes in left ventricular performance may be the result of variations in exogenous, as well as endogenous, catecholamines rather than intrinsic alterations in myocardial contractility. It is concluded that the VCFc/ESS relation permits a meaningful assessment of ventricular performance in critically ill neonates undergoing ECMO.

Cardiac Output↗
PubMed1992

Clinical profile and outcome of restrictive cardiomyopathy in children.

The clinical profile and outcome of idiopathic restrictive cardiomyopathy in a group of eight children are reviewed. There were six girls and two boys. Age at presentation was 4.0 +/- 2.6 years (range 1.3 to 9.5 years). All patients had evidence of congestive heart failure with systemic venous congestion. Right or left atrial enlargement was the most consistent ECG finding and was present in all patients. Left ventricular shortening fraction was normal in five patients, increased in two, and mildly reduced in one. The most striking echocardiographic feature was severe biatrial dilatation in the presence of normal or near-normal ventricular cavity dimensions. Marked elevation of left ventricular end-diastolic pressure was noted in all seven patients undergoing cardiac catheterization (34 +/- 7 torr; range 24 to 40 torr). Right ventricular end-diastolic pressure was elevated but significantly different from left ventricular pressure (18 +/- 7 torr; p less than 0.01). A characteristic early diastolic dip with a rapid rise to an elevated plateau (square root sign) was present in five of seven patients. Median survival was 1.4 years. Six patients died 0.2 to 7.0 years after they were initially seen. The actuarial survival rate 1.5 years after presentation was 44%, decreasing to 29% at 4 years. Restrictive cardiomyopathy has a worse prognosis in children than in adults. In part this may reflect the more advanced symptoms of congestive failure at initial presentation. Pediatric patients should be considered for early cardiac transplantation.

Cardiac Catheterization↗
PubMed1991

Outcome of infants and children with dilated cardiomyopathy.

A review of 81 infants and children with dilated, poorly contracting left ventricles without associated structural abnormalities was undertaken to identify risk factors for poor outcome, which could be used in selecting candidates for cardiac transplantation. Significant atrial or ventricular dysrhythmias, or both, were detected on presentation or during follow-up in 24 patients. Arrhythmias were present in only 8 of 51 survivors (16%) but were detected in 16 of 30 patients (53%) who died (p less than 0.05). Patients dying suddenly were even more likely to have had documented dysrhythmias (8 of 11, p less than 0.05). Left ventricular shortening fraction was similar in survivors and nonsurvivors (14.9 +/- 1.0% vs 15.3 +/- 1.7%). Left ventricular end-diastolic pressure in 44 patients who had cardiac catheterization averaged 20.8 +/- 1.6 mm Hg. Left ventricular end-diastolic pressure was significantly higher in patients who died than in those who survived (29.5 +/- 2.2 vs 15.0 +/- 1.6 mm Hg, p less than 0.001). Analysis of actuarial survival revealed that mortality was highest during the first 6 months after presentation (19% mortality). Survival declined more gradually thereafter and was 70% at 2 years, 64% at 5 years and 52% after 11.5 years. Age at initial presentation did not have any significant impact on survival. However, left ventricular end-diastolic pressure greater than 25 torr was associated with a significantly increased mortality rate (p less than 0.05). Early cardiac transplantation should be considered in patients with markedly elevated left ventricular end-diastolic pressure or complex atrial or ventricular arrhythmias.

Actuarial Analysis↗
PubMed1991

Comparisons between dental and skeletal ages.

Data from 694 untreated children seen in a private orthodontic practice were used to analyze associations between dental and skeletal maturity. Dental ages were obtained by comparison with Bolton Standards; skeletal ages were assessed using the Greulich-Pyle atlas. In some children the difference between the dental and skeletal ages was as large as 36 months; the difference was less than 6 months in fewer than 40% of the children. Regression analyses showed only moderate associations between these measures. One measure of maturity cannot be inferred from the other.

Age Factors↗
PubMed1991

Plasma catecholamine response to fetal hypoxemia is not potentiated by naloxone.

The interaction between the plasma catecholamine response to hypoxemia and endogenous opiate receptor blockade was investigated in 9 fetal lambs. The animals were randomly assigned to receive either normal saline (control group 1) or two doses of naloxone (group 2 = 0.5 mg/kg; group 3 = 1.0 mg/kg) by bolus injection followed by continuous infusion. Arterial PO2 decreased from 21 to 12 Torr and remained less than 14 Torr for 1 h. Arterial pH declined from 7.40 to a nadir of 7.32 at 1 h. Mean plasma catecholamine concentrations rose promptly from a baseline of 524-546 pg/ml for norepinephrine (NE) and 156-235 pg/ml for epinephrine (E) to reach a peak at 15 min (NE = 2,476-3,276, p less than 0.01; E = 1,856-4,065 pg/ml, p less than 0.01) and remained elevated thereafter. Neither dose of naloxone significantly altered plasma NE or E concentrations. Therefore, we conclude that endogenous opiates do not modulate the sympathoadrenal response to moderately long periods of hypoxemia unaccompanied by acidemia.

Animals↗
PubMed1990

A randomized clinical trial of inpatient family intervention. V. Results for affective disorders.

This paper reports the results at follow-up of a randomized clinical trial of combining family intervention with drug treatment during hospitalization for patients with affective disorder. The results suggest that female bipolar patients and their families benefited from family intervention, whereas unipolar patients and families did not. Patient outcome was positively correlated with the achievement of the goals of family intervention.

Adolescent↗
PubMed1990

Gender and schizophrenia outcome: a clinical trial of an inpatient family intervention.

Several studies document sex differences in premorbid and intermorbid role functioning, showing less functional deficit among females. The specific nature of sex differences in role functioning is still poorly understood. The purpose of the present study was to investigate sex differences in symptomatology and role functioning in a sample of 92 inpatients hospitalized for an episode of DSM-III-diagnosed schizophrenic disorder. Patients were randomized at hospital admission to either of two treatment conditions: (1) multimodal hospital treatment with the addition of an inpatient family intervention (IFI) or (2) multimodal hospital treatment without IFI. Results indicated (1) sex differences in levels of substance abuse and antisocial behavior (worse for males both at admission and followup)--dimensions of psychopathology unrelated to the core features of schizophrenia; (2) superior family and occupational functioning in females at followup; and (3) superior clinical response of females to IFI. Data on family response to IFI suggest some ameliorative effects of IFI on critical family attitudes toward female patients as well as greater family compliance with IFI treatment among the families of females. Sex differences in intermorbid family and occupational functioning and response to a family-based psychosocial intervention are discussed in light of data on rejecting family attitudes toward the patient and sex differences in symptomatology. The possible influence of sex-differentiated social role demands on response to IFI is also discussed.

Adult↗
PubMed1978

Administration of prostaglandin E1 in neonates with critical congenital cardiac defects.

Prostaglandin E1 was administered to 12 neonates and young infants in whom pulmonary or systemic blood flow was entirely or significantly dependent upon persistent patency of the ductus arteriosus. Nine neonates responded favorably to PGE1 infusion; their mean age was 2.8 days. Three infants who failed to respond were 10 days, 14 days, and 9 weeks of age, respectively. Six neonates with right ventricular outflow obstruction had a mean increase in arterial PO2 of 136% following administration of PGE1. In three patients in whom systemic flow was ductus dependent, PGE1 infusion was followed by improvement in arterial blood pressure, peripheral perfusion, and urine output. Complications included pyrexia, vasodilatation, and myoclonic jerks (or focal seizures). Three side effects were easily reversible by decreasing the infusion rate or altering the site of administration. PGE1 is a highly effective agent in stabilizing critically ill neonates with ductus dependent congenital cardiac lesions.

Blood Pressure↗
PubMed1978

Cardiovascular responses to autonomic blockade in brain-injured fetal lambs.

The cardiovascular responses to autonomic blockade were investigated in 15 late-gestation fetal lambs in utero. 4 animals had normal brains and 11 had hydranencephalic-like cerebral injury secondary to bilateral carotid artery obstruction (BCO). Following atropine administration, heart rate increased only 0.7 +/- 0.7% in the BCO lambs compared to 25.7 +/- 5.2% in the controls. alpha-Blockade with phentolamine resulted in a small decrease in systolic (2.2 +/- 0.8%) and diastolic (1.8 +/- 1.4%) blood pressure, and beta-blockade with propranolol produced a small decrease in heart rate (2.5 +/- 0.8%) as compared to control fetuses. Post mortem examination revealed extensive destruction of the cerebrum but normal hypothalamus and brain stem. These data suggest that supramedullary modification of autonomic cardiovascular control involves the cerebrum.

Animals↗
PubMed1978

Echocardiography and perfusion scintigraphy in the diagnosis of pulmonary arteriovenous fistula.

The echocardiographic and perfusion scintigraphic evaluation of an adolescent boy with a pulmonary arteriovenous fistula is reported. Contrast echocardiography following the rapid intravenous injection of indocyanine green dye was utilized to document extracardiac right-to-left shunting. Perfusion lung scintigraphy demonstrated the presence of a single large pulmonary arteriovenous fistula. Contrast echocardiography and perfusion scintigraphy are minimally invasive, safe and easily performed techniques for the rapid diagnosis of pulmonary arteriovenous fistula.

Adolescent↗
PubMed1977

A psychological theory of child abuse.

This paper presents a detailed study of two patients hospitalized in a closed psychiatric unit on which the treatment program emphasized dynamically oriented individual psychotherapy and family therapy. The first patient was hospitalized following physical abuse of her four-year-old daughter, while the second was hospitalized for a postpartum depression eight weeks following the birth of her first child, a girl. Although the presenting pictures in these two patients were markedly different, the psychodynamic patterns were so similar that a detailed comparison of the two cases seems to offer useful insight into some of the psychological causes of child abuse.

Adult↗
PubMed1977

The saddle angle: constancy or change?

Serial cephalometric radiographs of 165 children have been used to analyze age-associated changes in the saddle angle (Ba-S-N). There are mean decreases in this angle of about 5 degrees from birth to 2 years in those with either a Class I or a Class II occlusion; later changes are slight. The mean values tend to be slightly smaller in Class I boys than in those with Class II. Generally, the means are slightly larger in boys than girls but in adults this sex difference is in the reverse direction while remaining slight. It is reasonable to conclude that change is dominant in the first two years. Even after pubescence the angle is not constant but the changes are much smaller. The variability of the angle is greater for Class II than Class I individuals and its variability is greater in girls than boys after 12 years. Almost all the median increments are negative; that is, the flexure of the cranial base decreases with age particularly if the increments begin at the first available radigraph. This tendency is more marked in Class II then Class I occlusion. The increments are markedly variable in each occlusion group with large changes occurring in some individuals. Correlations between the saddle angles at different ages are high; this shows a marked constancy of the relative levels for individuals. The correlations between increments are small; presumably this reflects the small sizes of these increments relative to error terms. In the present group the saddle angle is positively correlated with Ba-N length, but the correlation between the saddle angle and either cranial vault length of stature are near zero. These findings show that there is marked constancy within individuals after the age of 2 years although, as noted earlier, there is marked variability in the size of the angle at particular ages and the serial data for some unusual individuals show large changes that are generally decreases.

Adolescent↗
PubMed1977

Late elongation of the cranial base.

A single logistic curve was fitted to serial data for three cranial base lengths (S-N, Ba-N, and Ba-S) in 33 boys and 26 girls. Elongation during pubescence plus adolescence is greater in boys than girls for each length. The maximum rate of pubescent elongation occurs earliest in Ba-N. There are no consistent sex differences in the maximum rates of elongation but they occur considerably earlier in girls. Similarly, girls reach 95% of their adult lengths at younger ages than boys.

Adolescent↗