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Biomedical subjects

E J Krane

Publications and source records attributed to E J Krane.

At least 19 recordsLinked to original sources

Postoperative pain management in children.

Postoperative pain management in children is a topic that has been neglected in the past but is currently an active field of interest and effort. Clearly, the child's cognitive understanding of and emotional response to pain are different than an adult's, and these differences make pain assessment and control more difficult. Ongoing work to develop more accurate techniques of estimating pain intensity in children may have helpful results. The effects of untreated pain in children are similar to those in adults but may have more long-term consequences in children. In the past, postoperative pain treatment in children was often inadequate, but newer techniques, such as continuous infusion of opioids, patient-controlled analgesia, epidural administration of opioids, and regional analgesia, hold promise for improved care in the future.

Analgesia, Epidural

Epidural opioids in children.

Experience with spinal opioids in children is limited but is expanding. Anatomy, pharmacology, technique, and results are reviewed. Complications and side effects are described.

Analgesia, Epidural

Comparison of the effects of halothane on skinned myocardial fibers from newborn and adult rabbit. I. Effects on contractile proteins.

The effect of halothane on maximal and submaximal Ca2+-activated tension development of the contractile proteins of newborn and adult cardiac muscle from rabbits was determined. Right ventricular muscle was removed from newborn and adult rabbits, and the sarcolemma was disrupted (skinned) by homogenization. Fiber bundles were dissected from the homogenate and mounted on tension transducers. Fiber bundles were alternately immersed in relaxing solution [( Ca2+] less than 10(-9) M) and contracting solutions (various [Ca2+] from 10(-5.6) to 10(-3.8) M), which were saturated with 100% N2 alone or with three concentrations of halothane-N2 mixture. In the absence of halothane, newborn skinned myocardial fibers were slightly more sensitive to submaximal Ca2+ concentrations than were adult myocardial fibers. [Ca2+] required for 50% maximum tension were 10(-5.43) M and 10(-5.31) M, respectively (P less than 0.05). Halothane (1-3%) decreased the maximal Ca2+-activated tension (at [Ca2+] = 10(-3.8) M) similarly in adult and newborn myocardial fibers in a dose-dependent fashion. Tension was reduced by 5.9% for each 1% increase in halothane concentration. Halothane also decreased the sensitivity of adult myocardial skinned fibers to submaximal Ca2+ concentrations (10(-5.6) M to 10(-5.0) M) by shifting the Ca2+-tension response curve to the right. Only 3% halothane decreased the sensitivity of newborn myocardial skinned fibers to Ca2+. The authors conclude that halothane causes less depression of Ca2+ activation of the contractile proteins in newborn than adult rabbit myocardium and that this effect of halothane cannot account for greater negative inotropy of halothane in the newborn.

Animals

The dose response of caudal morphine in children.

The authors compared the duration of analgesia and the frequency of side effects of three doses of caudal epidural morphine in children aged 1.2-7.9 yr. Caudal catheters were inserted in 32 children, randomly assigned to receive 0.033 mg.kg-1, 0.067 mg.kg-1, or 0.10 mg.kg-1 of preservative-free morphine for analgesia after major surgical procedures below the diaphragm. The first dose of caudal morphine was mixed with 0.25 ml.kg-1 of 1% lidocaine to confirm correct caudal catheter placement. By assessment of periodic pain scores and the time intervals between administration of caudal morphine and the recurrence of pain, the authors found that the mean (+/- SD) duration of analgesia was significantly longer after 0.10 mg.kg-1 (13.3 +/- 4.7 h) than after either 0.033 mg.kg-1 or 0.067 mg.kg-1 (10.0 +/- 3.3 and 10.4 +/- 4.2 h, respectively) (P less than 0.02). The frequency of vomiting, pruritus, and urinary retention was similar in each group. Vomiting was less common in patients who had nasogastric drainage than in patients who were fed soon after surgery (P less than 0.05). Delayed respiratory depression occurred in one child after 0.10 mg.kg-1 of caudal morphine. Caudal morphine, 0.033-0.10 mg.kg-1, provided prolonged analgesia in children. The authors recommend 0.033 mg.kg-1 of caudal morphine as an initial dose for children.

Child

Comparison of the effects of halothane on skinned myocardial fibers from newborn and adult rabbit: II. Effects on sarcoplasmic reticulum.

The effect of halothane on Ca2+ uptake or release by the sarcoplasmic reticulum (SR) was compared in the newborn and adult rabbit myocardium. The sarcolemma of right ventricular myocardium was disrupted (skinned) by homogenization. Fiber bundles were dissected from the homogenate, mounted on tension transducers, and immersed sequentially in five solutions that loaded Ca2+ into the SR, then in solutions containing either 2 or 25 mM caffeine to release SR-stored Ca2+, resulting in transient tension development. Experimental solutions were saturated with halothane in N2 gas during Ca2+ uptake by SR, Ca2+ release by SR, or during both SR Ca2+ uptake and release. Halothane (0.5-1.7%) resulted in dose-dependent depression of SR Ca2+ uptake in both newborn and adult skinned fibers. Less tension transient depression resulted in newborn (35%) than adult skinned fibers (49.5%, P less than 0.05) with 0.5% halothane exposure during SR Ca2+ uptake. Similar depression resulted in newborn (53.7% and 73.4%) and adult fibers (65.2% and 77.9%) with 1.0% and 1.7% halothane. Halothane had little effect on SR Ca2+ release by 25 mM caffeine but enhanced submaximal SR Ca2+ release by 2 mM caffeine more in newborn than adult myocardium. Increased Ca2+ efflux from newborn SR may contribute to the greater sensitivity of intact newborn cardiac muscle to exposure to halothane.

Aging

Diabetic ketoacidosis. Biochemistry, physiology, treatment, and prevention.

Diabetic ketoacidosis (DKA) is the most common cause of death of juvenile-onset diabetics, and as such represents an important issue for pediatricians. In this article, the author reviews the endocrinology of insulin and the glucose counter-regulatory hormones, which are the basis for the development of DKA. The effects of hyperglycemia and acidosis upon organ physiology are detailed, and this serves as the foundation for subsequent discussion of the management of the patient with DKA. Finally, the author summarizes current strategies for prevention of DKA in patients with diabetes.

Central Nervous System Diseases

Brain death?

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Brain Death

Caudal morphine for postoperative analgesia in children: a comparison with caudal bupivacaine and intravenous morphine.

We compared the efficacy, duration, and side effects of preservative-free morphine injected into the caudal space in children, with caudal bupivacaine and with intravenous morphine administration for relief of postoperative pain. Forty-six children, ages 1-16 yr, were randomly assigned to receive intravenous morphine (control group), caudal bupivacaine (0.25%, 1 ml/kg), or caudal morphine (0.5 mg/ml, 0.1 mg/kg). In half the patients given caudal morphine, the morphine was mixed with a dose of lidocaine adequate to produce sacral analgesia, to confirm correct caudal injection of the morphine. Caudal injections were performed at the end of surgery. Time until the first required postoperative intravenous morphine dose was recorded for each patient. The duration of analgesia was significantly greater with caudal morphine (median 12 hr, P less than 0.02) than with caudal bupivacaine (median 5 hr), and both were greater than with intravenous morphine in control patients (median 45 min). Urinary retention, pruritus, and nausea appeared with slightly greater frequency in the caudal morphine group, but no delayed respiratory depression occurred. Caudal morphine (0.5 mg/ml, 0.1 mg/kg) provided 8-24 hr of analgesia in children without a significantly greater incidence of side effects than caudal bupivacaine or intravenous morphine.

Adolescent

Comparison of the effects of halothane on newborn and adult rabbit myocardium.

The effect of halothane on myocardial contractility was studied in isolated right ventricular muscle preparations from newborn and adult rabbits. Right ventricular strips were mounted in oxygenated Krebs' solution and stimulated with supramaximal voltages at 1.0 Hz, while isometric force of contraction was continuously recorded. Halothane (0.4, 0.7, and 1.1%) caused a significant dose-dependent depression of both peak developed tension (42, 61, and 70%, respectively) and maximum rate of rise of isometric tension (40, 56, and 64%, respectively) of newborn myocardium. Newborn myocardial preparations exhibited approximately 20% greater depression of contractility than adult myocardium at each concentration studied (P less than 0.05), thus a parallel shift of the dose-response curves was observed. It was concluded that halothane exerts a potent depressant effect on newborn myocardium that is greater than that on adult myocardium. The depression effect of halothane on the newborn myocardium may contribute to its hypotensive effect in newborn infants.

Aging

Subclinical brain swelling in children during treatment of diabetic ketoacidosis.

Clinically apparent cerebral edema is a rare and often fatal complication of diabetic ketoacidosis. To determine whether subclinical brain swelling occurs more commonly, we obtained cranial CT scans in six children with diabetic ketoacidosis treated with fluid resuscitation and continuous low-dose insulin therapy. Control scans were obtained before hospital discharge. Compared with the scans during convalescence, the early scans of all six children showed a narrowing of the brain's ventricular system, compatible with brain swelling. Average changes in diameter were 1.3 +/- 0.1 mm for the third ventricle and 3.7 +/- 0.8 mm for the lateral ventricles (P less than 0.01). In addition, a narrowing of the subarachnoid spaces was subjectively noted during a blind reading of the early scans. Although no single scan was overtly indicative of cerebral edema, the data suggest that subclinical brain swelling may be a common occurrence during treatment of diabetic ketoacidosis in children. Sequential CT scans of the brain may provide a means of evaluating modifications of standard therapy aimed at preventing cerebral edema.

Adolescent

Continuous variability of fetal PO2 in the chronically catheterized fetal sheep.

A method of continuous monitoring of fetal intravascular PO2 at various sites in the circulation in the chronically catheterized fetal sheep for up to 41 days (mean 11.1 days) has been compared with values obtained in blood samples measured extracorporeally in a standard blood gas analyzer. A double-blind comparison of the two methods showed that there was no bias between the two methods and correlation was 0.94. The stability of the electrodes was superior to that of a conventional blood gas analyzer. In every animal there was continuous variability of fetal vascular PO2. In the period from 105 to 126 days' gestation we noted the presence of slow increases in basal uterine tone that we have called "contractures". The frequency of these contractures was very regular at approximately one per hour. The frequency of these contracutres was very regular at approximately one per hour. There is a statistically significant related fall in fetal vascular PO2 in relation to these contractures. Well-coordinated uterine contractions during labor also produced a fall in fetal vascular PO2 that was related to the uterine activity.

Animals

Pituitary stalk-section and some of its effects on endocrine function in the fetal lamb.

A detailed description is given of a method to section the pituitary stalk of the fetal lamb after 105 days gestational age. The approach to the stalk is made through a window in the frontal bone. In order to prevent regeneration of the hypothalamo-pituitary connections a silicone plate is introduced through the probe used to fracture the stalk. The surgical outcome and viability of 11 pituitary stalk sectioned fetuses is described over periods of up to 23 days. The presence of pituitary infarction following stalk section was related to damage of the anterior hypophysial vesssels if the probe was deviated from the mid-line at any time in its course. The effect of this procedure on fetal plasma T4 and PRL concentrations and the initiation of premature labour by the continuous infusion of cortisol into the fetus is described.

Animals

Ultrastructural changes in the placenta of the ewe after fetal pituitary stalk section.

Binucleate cells are a normal component of the ovine chorionic epithelium, but are usually separated from the fetal-maternal interface by a thin layer of cytoplasm derived from the principal or uni-nucleate cells of the trophoblast. They are distinguished not only by two distinct and separate nuclei, but also by conspicuous membrane-bound cytoplasmic inclusions in the form of haloed droplets. After fetal pituitary stalk section binucleate cells move up to and participate in the formation of the fetal-maternal interface; furthermore they extend clear blunt-ended pseudopodia into the maternal epithelial syncytium. These activities do not appear to be supppressed by fetal infusion of cortisol or ACTH. The apparent motility of binucleate cells, together with the presence of haloed droplets within the maternal epithelial syncytium, suggests that after fetal pituitary stalk section binucleate cells invade the uterine syncytium, lose their limiting membranes and discharge their contents into the syncytial cytoplasm. Large molecules such as ovine placental lactogen may be transported from fetal to maternal tissues by this mechanism.

Adrenocorticotropic Hormone

Changes in the fetal thyroid axis after induction of premature parturition by low dose continuous intravascular cortisol infusion to the fetal sheep at 130 days of gestation.

The effect of cortisol infusion on plasma T4 and T3 concentrations has been investigated in the fetal lamb at 130-134 days of gestation. Infusion of cortisol at rates equivalent to one-third the quantity produced by the fetus at the time of parturition results in a significant fall in fetal plasma T4 concentration and a significant rise in fetal plasma T3 concentration. Delay in the initiation of labor as a result of progesterone administration to the ewe did not prevent the changes in the fetal thyroid axis. These modifications of thyroid function therefore appear to be caused by the infusion of cortisol rather than to be secondary to the induction of labor.

Animals