PubMed Health⌕ Search

Biomedical subjects

C D Rudolph

Publications and source records attributed to C D Rudolph.

At least 19 recordsLinked to original sources
PubMed1998

Gastrointestinal manometry studies in children.

Children with gastrointestinal motility disorders present with diverse symptoms, and obtaining a detailed history is often impossible. As in adults, evaluation of a suspected motility disorder begins with exclusion of mechanical obstruction or primary inflammatory disorders. Subsequently, coordination of peristaltic function is evaluated in those segments of the gastrointestinal tract that are suspected to be abnormal based on the clinical history. Evaluation of gastrointestinal motility in children is particularly challenging because of frequent lack of patient cooperation and difficulties in adapting the equipment to patient size. This review discusses the indications and approach to the evaluation of motility of each region of the gastrointestinal tract in infants and children.

Adult↗
PubMed1995

Effect of increased intra-abdominal pressure on hepatic extraction and clearance of fentanyl in neonatal lambs.

Fentanyl, an opioid metabolized by hepatic mixed function oxidases, is commonly administered as the primary anesthetic for neonates undergoing surgery. Pharmacokinetic studies have suggested that abdominal surgery in neonates decreases fentanyl clearance, contending that this results from increases in intra-abdominal pressure (IAP) decreasing hepatic blood flow. To examine the effects of IAP on hepatic blood flow and fentanyl clearance, we infused fentanyl to eight neonatal lambs, measured regional blood flows by using the radionuclide-labeled microsphere technique and determined hepatic fentanyl extraction and clearance and hepatic oxygen extraction and consumption at three levels of IAP: 0, 12 and 18 mm Hg. Increased IAP did not affect portal or hepatic blood flow or ductus venosus shunt. Fentanyl extraction was 16.5 +/- 3.0% (mean +/- S.E.) at 0 mm Hg of IAP. Increased IAP decreased hepatic extraction of fentanyl, thereby decreasing fentanyl clearance. Increased IAP did not affect hepatic oxygen extraction or consumption. In two additional animals in which serial measurements of hepatic blood flow were obtained, increased IAP (15 mm Hg) transiently decreased hepatic blood flow with recovery to control values at 2 hr. The authors conclude that fentanyl is poorly extracted by neonatal livers, in contrast to its large extraction ratio in adults. The decrease in fentanyl clearance with increased IAP is consistent with pharmacokinetic studies demonstrating decreased clearance in neonates undergoing abdominal surgery. However, the present study suggests that the mechanism of decreased clearance is decreased hepatic function (decreased fentanyl extraction) rather than decreased hepatic blood flow.

Abdomen↗
PubMed1994

Development of gastrointestinal motility in the infant and child.

The neuromuscular apparatus of the gastrointestinal tract develops early in gestation, but normal patterns of innervation and contractile activity are not achieved until near birth. This article reviews the ontogeny of gastrointestinal neuromuscular anatomy and the development of coordinated peristaltic function in the different regions of the gastrointestinal tract. This information provides a basis for understanding the difficulties encountered in successfully providing enteral feeding to the preterm infant.

Animals↗
PubMed1994

Pediatric endoscopy.

Explore the source record for details and available documents.

Anti-Bacterial Agents↗
PubMed1994

Introduction to pediatric esophagogastroduodenoscopy and enteroscopy.

Pediatric esophagogastroduodenoscopy is now an integral part of the practice of pediatric gastroenterology. Children are not just small adults. The differing clinical indications, approaches to patient preparation, sedation, and complications are discussed in this article.

Anesthesia↗
PubMed1993

Chronic recurrent esophageal strictures treated with balloon dilation in children with autosomal recessive epidermolysis bullosa dystrophica.

Two children (8- and 17-yr old) with autosomal recessive epidermolysis bullosa dystrophica and chronic esophageal strictures were treated with repeated balloon dilations. General anesthesia was by face mask adapted specifically for this procedure, with careful attention to avoid skin and mucus membrane damage. A balloon dilator positioned fluoroscopically over an angiographic guidewire was gently inflated until narrowings resolved. Dilations have been performed every 1-11 [4.3 +/- 3.2 (mean +/- SD)] months in the younger patient over the last 4.3 yr, and every 8-20 (14.5 +/- 5.9) months in the older patient over the last 4.8 yr, without serious complications. Both patients were able to swallow normal foods following dilations. Repeated balloon dilations of esophageal strictures in patients with epidermolysis bullosa dystrophica can be done safely. Further studies are indicated to determine its effectiveness and appropriateness as an alternative to colonic interposition.

Adolescent↗
PubMed1992

Amino acid gradients across the intestinal circulation in fetal lambs.

Amino acids, including glutamine, glutamate and asparagine are major metabolic substrates for the adult enterocyte of several species. To determine whether circulating amino acids are utilized by the fetal intestine, we studied nine fetal sheep (mean gestational age 128 +/- 5 days; term: 147 days). Catheters were inserted into the descending aorta (DA) and the mesenteric vein (MV) to allow for simultaneous blood sampling across the intestine. Fetal blood gas, haemoglobin; O2 saturation and O2 tension were measured. Ammonia was determined by an enzymatic method and HPLC analysis was used to measure the content of all amino acids in DA (descending aorta) and MV (mesenteric vein). Intestinal blood flow measurements were obtained using the radionuclide microsphere method. Intestinal blood flow (81 +/- 28 ml/min/100g) and arterial pH (7.37 +/- 0.04) were within normal range for unstressed fetal lambs. Glutamine and glutamate were the only amino acids that were significantly taken up across the fetal intestinal circulation. The fetal intestine extracted approximately 21% of the delivered glutamine (6.8 +/- 4.5 mumol/min/100g), 7% of the delivered glutamate (1.3 +/- 1.1 mumol/min/100g) and 2.7% of the delivered oxygen (43.0 +/- 19.1 mumol/min/100g). These data suggest that glutamine and glutamate are major substrates for the intestine in unstressed fetal lambs.

Alanine↗
PubMed1991

Umbilical and hepatic venous responses to circulating vasoconstrictive hormones in fetal lamb.

Acute fetal hypoxemia increases the vascular resistance of the umbilical veins as well as that of the liver. Because, at least in the human, the umbilical-placental circulation has no autonomic innervation, circulating hormones could well be responsible for this increase in umbilical-placental outflow resistance. In chronically instrumented fetal sheep, norepinephrine, epinephrine, vasopressin, and angiotensin II were infused in sequentially increasing doses into the descending aorta and vascular resistance to umbilical-placental blood flow was measured. Norepinephrine and epinephrine increased the vascular resistance of the umbilical veins in a dose-dependent manner. Both catecholamines also increased the vascular resistance of the liver, resulting in an increase in ductus venosus blood flow. In contrast, vasopressin and angiotensin II had no effect on umbilical-placental outflow resistance. Thus catecholamines may be responsible for the increase in the vascular resistance of the umbilical veins and liver in response to acute fetal hypoxemia.

Angiotensin II↗
PubMed1991

No-enema therapy for idiopathic constipation and encopresis.

Idiopathic constipation and encopresis of childhood are thought to occur when children volitionally withhold stool. Withholding may be prompted by social pressures or by episodes of painful defecation. Repetitive withholding may result in colonic dilatation and colorectal dysfunction. Therapy involves removal of impacted stool, stool softening, and behavioral therapy. The use of enemas in this therapy is widespread but may be counterproductive. A retrospective review of patients treated without enemas revealed 45 patients whose course could be followed for six months. Ninety-eight percent of these had successful initial cleanouts without enemas; 94% had continued success at six months. These results, comparable with other treatment programs, demonstrate that therapy without enemas is a reasonable alternative in the treatment of childhood constipation and encopresis.

Child↗
PubMed1991

Effects of ductus venosus obstruction on liver and regional blood flows in the fetal lamb.

The ductus venosus allows highly oxygenated blood returning from the umbilical-placental circulation to bypass the liver, and is believed thereby to facilitate preferential distribution of this blood to the fetal brain and heart. To examine this hypothesis, we developed a model that allows acute obstruction of the ductus venosus in chronically catheterized fetal lambs. In seven fetal lambs, a Swann-Ganz catheter was inserted into the inferior vena cava and the balloon tip advanced into the ductus venosus. Control measurements were obtained 1-2 d after surgery, before and during inflation of the balloon in the ductus venosus. At each sample time, radioactive microspheres were injected to determine organ blood flow and the distribution of umbilical venous blood flow. During balloon inflation, the percentage of umbilical venous return passing through the ductus venosus was reduced from 38 +/- 15% to 1 +/- 0.5%. Umbilical-placental blood flow was unchanged from control values of 181 +/- 33 mL/min/kg. Total liver blood flow increased from 346 +/- 98 to 553 +/- 105 mL/min/100 g. Pressure in the inferior vena cava did not change, but umbilical venous pressure increased from 7.2 +/- 2.7 to 8.7 +/- 3.5 mm Hg. Total vascular resistance across the liver and ductus venosus increased from 0.013 +/- 0.006 to 0.020 +/- 0.011 during ductus venosus obstruction. Fetal heart rate, arterial blood pressure, and descending aortic pH and blood gases were unchanged, as was oxygen content in the descending aorta and carotid artery. Organ blood flows, combined ventricular output, and oxygen delivery were also unchanged. In five animals, these studies were repeated during maternal hypoxemia.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Hemodynamic responses to alpha-adrenergic blockade during hypoxemia in the fetal lamb.

The mechanisms responsible for the increase in umbilical venous and hepatic vascular resistance during hypoxemia are poorly understood. To assess the relative importance of alpha-adrenergic receptors, we produced an acute, severe hypoxemia in chronically instrumented fetal sheep. While fetal arterial oxygen saturation was maintained at the same level, we then injected phentolamine, a selective alpha-adrenoreceptor blocker. We found that the hypoxemia-induced vasoconstriction of the umbilical veins and hepatic vasculature was reversed by alpha blockade. Thus, alpha-adrenergic stimulation is necessary to maintain vasoconstriction of the umbilical veins and hepatic vasculature during acute fetal hypoxemia. Furthermore, alpha-adrenergic stimulation is responsible for the hypoxemia-induced vasoconstriction of the gut, spleen, and lower carcass. Thus, the alpha-adrenergic system mediates important fetal hemodynamic adaptations to acute hypoxemia. However, the alpha-adrenergic system is not responsible for the hypoxemia-induced constriction of the renal vasculature.

Adrenergic alpha-Antagonists↗
PubMed1991

Cortisol induces perinatal hepatic gluconeogenesis in the lamb.

To examine the influence of a prenatal increase in plasma cortisol concentration on perinatal initiation of hepatic gluconeogenesis, we infused cortisol into seven fetal sheep at 137-140 days gestation. 14C-Lactate provided tracer substrate for estimation of gluconeogenesis. We measured hepatic blood flow using radionuclide-labeled microspheres. After delivery, fetal arterial blood glucose concentration (1.33 +/- 0.4 mmol/l) increased transiently, but returned to fetal levels within 1 h after delivery. Substantial hepatic gluconeogenesis was induced in the fetus after cortisol infusion, averaging 23.4 +/- 12.2 mumol/min/100 g liver (7.8 +/- 4.4 mumol/min/kg fetal weight). Fetal hepatic glucose output was 44.4 +/- 17.7 mumol/min/100 g liver. Hepatic glucose output did not change after delivery; estimated gluconeogenesis decreased immediately, then increased by 6 h after delivery. Lactate supply to the liver fell substantially, from 1.1 +/- 0.4 mmol/min/100 g in the fetus to 0.24 +/- 0.09 at 1 h after delivery. Lactate flux across the liver decreased from 75.3 +/- 23 mumol/min/100 g in the fetus to 20.2 +/- 15.7 at 1 h after delivery. Hepatic lactate flux was significantly related to gluconeogenesis (r = 0.734, P = 0.0001). We conclude that cortisol induces substantial hepatic gluconeogenesis in fetal sheep near term. After delivery, there appears to be a transient decline in gluconeogenesis from lactate, which may be secondary to limited hepatic oxygen and substrate supply. Onset of gluconeogenesis in the fetus fails to sustain increases in either fetal or postnatal blood glucose concentrations.

Animals↗