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Biomedical subjects

D W Benson

Publications and source records attributed to D W Benson.

At least 163 records · Page 9Linked to original sources
PubMedDate not supplied

Reversible cardiomyopathy due to carnitine deficiency from renal tubular wasting.

The clinical course of a 4-month-old male infant with a dilated cardiomyopathy secondary to renal tubular losses of carnitine is outlined. He was admitted to the hospital with severe congestive heart failure. An echocardiogram demonstrated normal anatomy. The left ventricular shortening fraction measured 10%. A comprehensive cardiomyopathy evaluation was initiated. The total plasma carnitine level was only 25 mumol/ml, but the urine carnitine measured 434 nm/mg of creatinine. He was begun on oral L-carnitine and weaned from mechanical ventilation and inotropic support 10 days later. Two years later he remains asymptomatic with normal left ventricular function.

Cardiomyopathy, Dilated↗
PubMedDate not supplied

Pharmacodynamics and pharmacokinetics of esmolol, a short-acting beta-blocking agent, in children.

Esmolol, a short-acting intravenous cardioselective beta-blocking agent, was evaluated for age-dependent pharmacodynamic and pharmacokinetic features in 17 young patients (6 months to 14 years). A loading dose (500 micrograms/kg/min) alternating with a maintenance dose (25-200 micrograms/kg/min, titrating by 25 micrograms/kg/min every 4 min) was infused until the heart rate or mean arterial pressure decreased 10%. Cardiac index, left ventricular shortening fraction, and systemic vascular resistance were measured at baseline, peak esmolol effect, and recovery. Serum esmolol concentrations were obtained to determine the half-life and the elimination rate constant. Esmolol reduced the heart rate, blood pressure, shortening fraction, and cardiac index in all patients, but it did not change systemic vascular resistance. Maintenance esmolol dose was 118 +/- 49 micrograms/kg/min, and the half-life was 2.88 +/- 2.67 min. Blood pressure and heart rate returned to normal within 2-16 min, but cardiac index and shortening fraction took longer to recover. There were no statistically significant age-dependent pharmacodynamic effects, but blood pressure decreased prior to heart rate and cardiac index took longer to recovery in patients who weighed < or = 15 kg. The pharmacokinetic profile in young patients was similar to that of older patients, but the half-life was shorter. The only side effect was transient nausea and vomiting in one patient. Esmolol is a safe and efficacious beta-blocking agent in young patients.

Adolescent↗
PubMedDate not supplied

Echocardiographic prediction of neonatal ECMO outcome.

Cardiopulmonary physiology was assessed by Doppler echocardiography in neonates undergoing pre-ECMO evaluation for meconium aspiration syndrome, congenital diaphragmatic hernia, persistent fetal circulation, and sepsis, from March 1987 through July 1992 (n = 136). Percent survival by diagnosis was: meconium aspiration syndrome, 86%; persistent fetal circulation, 68%; congenital diaphragmatic hernia, 63%; sepsis, 33%. Survival odds by diagnosis predicted a better outcome for meconium aspiration syndrome than for congenital diaphragmatic hernia and sepsis, and a better outcome for persistent fetal circulation than for sepsis. Percent survival for right-to-left patent ductus arteriosus flow (PDA) was 56%; other patent ductus arteriosus flow was 84%. In multivariate analysis, percent survival in congenital diaphragmatic hernia and persistent fetal circulation patients with right-to-left PDA flow suggested a worse outcome (% survival right-to-left vs other: congenital diaphragmatic hernia, 13% vs 70%; persistent fetal circulation, 25% vs 85%), whereas percent survival did not appear to suggest the same in meconium aspiration syndrome or sepsis patients. Similar analysis in non-ECMO patients suggested a worse outcome with right-to-left PDA flow in patients with meconium aspiration syndrome and congenital diaphragmatic hernia. Right-to-left PDA flow, sepsis, and congenital diaphragmatic hernia were associated with a poorer ECMO outcome. Initial assessment of PDA flow helps predict ECMO outcome.

Ductus Arteriosus, Patent↗
PubMedDate not supplied

Stress fractures of the femur in runners.

Early diagnosis, followed by conservative management, permitted five of six long-distance runners to return to running after they had suffered stress fractures of the femur. The sixth patient developed a displaced fracture of the femoral neck which was openly reduced and internally fixated at surgery: this athlete returned to marathoning one year later. In the series there were two fractures of the femoral neck and four of the proximal medical shaft of the femur. Although early diagnosis depends upon a complete history, physical examination and x-ray film results, bone scanning is a further aid when x-ray films still do not confirm the presumptive diagnosis.

Adult↗
PubMedDate not supplied

Theoretic significance of pH dependence of narcotics and narcotic antagonists in clinical anesthesia.

Determination of the effect of pH and temperature on pKa partition, and drug distribution coefficients in a series of common narcotics and their antagonists has shown that within the range of blood pH (7.1 to 7.7) encountered in the practice of anesthesiology, marked differences of distribution of the drugs between a model lipid (octanol) and water can occur. When these data are considered in the light of clinical experience with narcotics used in patients undergoing or recovering from surgical procedures, a correlation between the depth and duration of narcosis or the efficacy of narcotic antidotes and ventilatory status is seen. This correlation can be explained in part if the influence of blood pH on the probable CNS/blood distribution of a given drug is taken into consideration. Support is given to this proposal by representative studies in the literature. The very different drug distribution coefficients of two closely related narcotic antagonists, naloxone and naltrexone, correctly predicted the faster onset and shorter duration of the former, which was confirmed by reported clinical observations.

Anesthesia↗
PubMedDate not supplied

Venous air embolism: comparative merits of external cardiac massage, intracardiac aspiration, and left lateral decubitus position.

The treatment of venous air embolism was compared in adult mongrel dogs utilizing left lateral decubitus position, external cardiac massage, and intracardiac aspiration of air. Following the rapid injection of a lethal dose (15 ml/kg) of air, it was found that the left lateral decubitus position and external cardiac massage each produced 57.1 percent survival, both being as effective as intracardiac aspiration of air (61.9 percent survival). Resuscitation time was shortest in dogs treated with intracardiac aspiration, 2.7 +/- 0.28 minutes, whereas with external cardiac massage and left lateral decubitus position, resuscitation times were 18.3 +/- 2.1 minutes and 19.50 +/- 3.0 minutes, respectively. Our study shows external cardiac massage, left lateral decubitus position, and intracardiac aspiration to be equally effective in the treatment of venous air embolism. Our data did not show intracardiac aspiration to be superior to either external cardiac massage of left lateral decubitus position despite the shorter resuscitation time. External cardiac massage has the advantage of simplicity and speed of initiation.

Animals↗
PubMedDate not supplied

Heart transplantation in neonates and in children.

Between May 1988 and July 1991, 28 neonates and children underwent orthotopic heart transplantation at Children's Memorial Hospital in Chicago. Indications for heart transplantation were hypoplastic left heart syndrome (10), dilated cardiomyopathy (13), aortic stenosis with endocardial fibroelastosis (1), complex D-transposition of the great arteries after Senning repair (1), L-transposition of the great arteries with single ventricle after shunt (1), cor biloculare, pulmonary atresia, and situs inversus after Fontan (1), and chronic rejection after heart transplantation for hypoplastic left heart syndrome (1). The age at time of transplantation ranged from 2 days to 17 years (mean, 5.3 +/- 6.1 years). Early deaths were from intraoperative donor right ventricular failure (2) and acute rejection after a second transplant procedure at 21 days (1), for an in-hospital mortality rate of 10.7%. Immunosuppression was with cyclosporine, azathioprine, and prednisone, with an attempt to discontinue the prednisone in neonates at age 6 months as guided by endomyocardial biopsy. Rejection episodes were treated with methylprednisolone pulse (34) or with OKT3 (4). Endomyocardial biopsy (in patients older than 6 months) was used extensively, and acute rejection was diagnosed in 29 of 301 biopsies. Three late deaths occurred (mean follow-up, 16.3 +/- 11.8 months): one of acute rejection at 13 months, one of viral pneumonia at 7 months, and one of intraabdominal sepsis as a complication of peritoneal dialysis at 5 months. Actuarial survival at 2 years is 77% +/- 9% (standard error of the estimate). Heart transplantation for neonates and for children can be performed with acceptable operative mortality. Intermediate results with triple therapy immunosuppression and an intensive rejection surveillance regimen relying on endomyocardial biopsy are encouraging.

Actuarial Analysis↗