Advance directives in a pediatric emergency department.

Parents of children with terminal illnesses are not always present when a life-threatening event occurs. For many of these children, an advance directive specifying alternate code orders has been written by the parent or legal guardian (hereafter the use of parent is to be interpreted as parent/legal guardian) and the patient's attending physician. Implementing a pediatric advanced directive presents significant problems for emergency personnel if the parent is not present to identify the existence of the directive and interpret the contents in the context of the current medical crisis.

Optic chiasm glioma associated with inappropriate secretion of antidiuretic hormone, cerebral ischemia, nonobstructive hydrocephalus and chronic ascites following ventriculoperitoneal shunting.

An optic chiasm glioma may cause loss of vision, endocrine disturbances, hydrocephalus and cerebral ischemia due to its proximity to the pituitary, hypothalamus, III ventricle and internal carotids. A 3-month-old infant with optic chiasm glioma developed hypopituitarism and inappropriate secretion of antidiuretic hormone with plasma hypo-osmolality. The cerebrospinal fluid (CSF) protein concentration was markedly elevated. The impairment of fluid absorption via arachnoid villi and peritoneum by the high protein content, and reversed osmotic gradient between protein-rich CSF and hypo-osmolar plasma may have contributed to both nonobstructive hydrocephalus and recurrent ascites following ventriculoperitoneal shunting. Cerebral ischemia from carotid compression may have led to cerebral atrophy.

Cholinergic control of smooth muscle peristalsis in the cat esophagus.

The aim of this study was to examine in detail the effects of selective cholinergic and other pharmacological antagonists on primary and secondary peristalsis in the smooth muscle of the cat esophagus in order to fully characterize the cholinergic contribution to peristalsis in this species. Primary and secondary peristalsis in the smooth muscle part of the feline esophagus was completely abolished by atropine, 4-dephenylacetoxy-N-methylpiperidine methiodide (4-DAMP) (a selective M2 muscarinic antagonist), hexamethonium, and high doses of nicotine. Pirenzepine (a selective M1 muscarinic antagonist), propranolol, and phentolamine were without effect, as were naloxone, methysergide, and pyrilamine. From these findings we conclude that primary and secondary peristalsis in feline esophageal smooth muscle involves nicotinic ganglionic neurotransmission as well as postganglionic release of acetylcholine that acts directly on muscarinic receptors located on the smooth muscle. Peristalsis in esophageal striated muscle does not involve either synaptic transmission or muscarinic receptors.

Gastrointestinal myoelectric activity in an infant with congenital idiopathic motility disorder.

We investigated myoelectric activity in an 8-month-old male who presented with a perinatal bowel obstruction, duodenal band, congenital short small intestine, and persistent feeding intolerance. Serosal electrodes were surgically implanted on stomach, duodenum, and jejunum during Nissen fundoplication and ileostomy. A 5-cm ileal specimen was taken for in vitro studies. Spontaneous migrating myoelectric complexes (MMC) were present in stomach and small intestine. Bethanechol increased electrical response activity (ERA) in stomach and duodenum. Morphine induced intense ERA and distinct phase III activity. Pentagastrin infusion did not disrupt MMC cycling. Feeding disrupted MMC complex cycling 30-40 min after the meal. Metoclopramide before feeding delayed disruption of the MMC cycling after the feeding. Intermittent gastric arrhythmias were present after the fifth postoperative day. In vitro muscle strips showed spontaneous contractions and electrical control activity (ECA). Bethanechol, McNeil A-343, motilin, and cholecystokinin induced contractions, but pentagastrin had no effect. We conclude that in spite of a major clinical motility dysfunction, several of our findings were normal. The abnormalities include short MMC period, absence of disruption of MMC by pentagastrin, and gastric arrhythmias.

Electrical control activity of the lower esophageal sphincter in unanesthetized opossums.

We recorded lower esophageal sphincter (LES) pressure and myoelectrical activity concurrently from the esophagus, LES, stomach, and proximal small intestine in unanesthetized opossums. LES electrical activity was characterized by almost continuous, spikelike oscillations at 15-40/min, which were accompanied by minicontractions 5-15 mmHg in amplitude. Basal LES pressure, however, did not depend on electrical oscillations. The LES exhibited cyclic changes in pressure and electrical activity synchronous with gastric contractions associated with the migrating myoelectric complex (MMC). During phase I, the LES pressure was stable and its electrical activity showed continuous low-amplitude (less than 0.3 mV) oscillations at a rate of 20 +/- 2 per min. During phases II and III of MMC-related gastric activity, the LES developed strong phasic contractions, while the electrical oscillations grouped into clusters with an increased rate (32 +/- 1 per min) and amplitude (0.4-0.8 mV), each cluster corresponding to a phasic contraction. Feeding, pentobarbital, and cholinergic blockade abolished MMC-related LES activity and resulted in a steady rate of LES electrical oscillations. LES relaxation induced by swallows or esophageal balloon distention abolished the LES electrical oscillations. Increases in LES pressure induced by pharmacological and hormonal stimulation correlated with concurrent increases in the rate of electrical oscillations. We conclude that the opossum LES has a unique pattern of electrical activity that differs from the electrical activity recorded from smooth muscle elsewhere in the gastrointestinal tract. This electrical activity is a form of control wave associated with a minicontraction. Phasic LES contractions during the intestinal MMC cycle may result from an increase in the rate and amplitude of the LES electrical control waves and fusion of minicontractions.

Endoscopic retrograde cholangiopancreatography in children.

Endoscopic retrograde cholangiopancreatography (ERCP) is a universally used diagnostic and therapeutic modality in adults with pancreaticobiliary tract disease; its use in children with similar problems has been limited. We have performed ERCP procedures in 39 children and adolescents (aged 6 months to 18 years; mean 12.5 years), using the standard adult and pediatric side-viewing endoscopes. In selected cases, ERCP manometric study of the sphincter of Oddi, endoscopic sphincterotomy, or balloon extraction of common bile duct stones was performed. Nineteen patients had significant or abnormal structural findings, including pancreas divisum (four patients); sclerosing cholangitis (three); and choledochal cyst, chronic pancreatitis, choledochocele, pancreatic pseudocyst, common bile duct stone, and sphincter of Oddi motor dysfunction (two each). In all instances in which patients required operation, ERCP examination provided specific anatomic detail that was useful for planning appropriate intervention. The only significant complication after ERCP was mild pancreatitis, which occurred in four patients and responded to supportive, short-term measures.

Hepatic ultrastructure in leukemic children treated with methotrexate and 6-mercaptopurine.

Methotrexate (MTX) and 6-mercaptopurine (6MP), the two drugs most commonly used for maintenance treatment of childhood leukemia, are both potent hepatotoxins. In order to assess MTX-6MP-induced damage, we obtained biopsies from 11 children with acute lymphocytic leukemia (ALL) for light microscopic and transmission electron microscopic study. Prednisone, vincristine, and L-asparaginase were used for induction of remission in all patients. Although light microscopic findings were minimal, we found significant ultrastructural abnormalities in all patients. Changes included nuclear abnormalities, disruption of rough and smooth endoplasmic reticulum, a variety of mitochondrial changes, steatosis, fibrosis, and changes in peroxisomes and lysosomes. These abnormalities could not have been predicted from liver function tests or histopathology. Three of the eleven patients studied had also received cyclophosphamide and cytosine arabinoside during maintenance therapy. The ultrastructural abnormalities in this group were not distinguishable from those observed in the group that did not receive these additional chemotherapeutic agents. The long-term clinical significance of these findings is not known.