SUMMARY Measurements were made of distal radius, mid‐radius, tibia and metatarsal bone‐density of 80 patients with myelomeningocele (17 thoracic, six L1/L2, 13 L3, 30 L4, 14 L5/sacral). For the upper extremity the bone density primarily was low in the thoracic patients, but in the tibia and metatarsal it showed a more linear correlation with neurological levels. The effect of age was highly significant at all sites; after controlling for this, the neurological level was a significant determinant of bone density at all sites, and this effect was greater in older children. Patients with impaired ambulation had decreased bone‐density in the distal radius, tibia and metatarsal, but not in the mid‐radius. Race had no significant effect on density after accounting for differences in neurological level. Weight for height and multiple fractures did not correlate with bone density. Although ambulatory status (weight‐bearing stresses) and neurological status (muscle stresses) are both important factors in bone density, this study suggests that the latter is a more important determinant. Résumé Densité osseuse dans le myéloméningocèle: effet du statut ambulatoire et autres facteurs La densité osseuse a été mesurée à radius distal, mi‐radius, sur le tibia et les métarsiens chez 80 sujets présentant un myéloméningocèle (17 de niveau thoracique, six L1/L2, 13 L3, 30 L4, 14 L5/sacré). A l'extrémité supearieure, la densité osseuse était fondamentalement basse chez les sujets à atteinte thoracique, mais la densité osseuse montrait une meilleure corrélation linéaire avec les niveaux neurologiques sur le tibia et les métatarses. L'effet de l'âge était hautement significatif sur tous les os; après correction de l'âge, le niveau neurologique influencait significativement la densité osseuse sur tous les os étudtés, cet éffet etant plus marqué chez les enfants plus âgés. Chez les sujets sans déambulation, la densité osseuse était abaissée à la partie distale du radius, sur le tibia et les métatarsiens mais non à mi‐radius. La race n'avait pas d'effet significatif sur la densite apres correction des differences liees au niveau neurologique. Ni le poids pour la taille, ni les fractures multiples n'apparaissaient avoir d'action sur la densité osseuse. Bien que le statut ambulatoire (effet de pesanteur) et le statut neurologique (effet de traction des muscles) sont tous deux des facteurs importants de la densité osseuse, cette étude suggère que ce dernier statut est les plus important. ZUSAMMENFASSUNG Knochendichte bei Myelomeningocele: der Einfluß der Gehfähigkeit und anderer Faktoren Bei 80 Patienten mit Myelomeningocele (17 thorakal, sechs L1/L2, 13 L3, 30 L4, 14 L5/sakral) wurden im Bereich distale Radius, mittlerer Radius, Tibia und Metatarsus Knochendichten gemessen. In der oberen Extremität war die Knochendichte hauptsächlich bei Patienten mit thorakaler Läsion niedrig, in Tibia und Metatarsus dagegen zeigte die Knochendichte eine mehr lineare Korrelation mit dem neurologischen Befund. Bei alien Lokalisationen fand sich ein hochsi...
SUMMARY The association of race and gender with different neurological levels of myelomeningocele was studied in 251 patients. Over‐all, the white to black ratio was 3·6 and the male to female ratio was 0·86. However, the proportions of whites and females were significantly increased in thoracic‐level patients (white to black ratio 13·6, male to female ratio 0·43), whereas the lumbar‐level patients had sex and white to black ratios equivalent to the area population. This supports the concept that thoracic‐level myelomeningocele has a different pathogenesis from lumbar‐level. RÉSUMÉ Effets de la race et du sexe sur le niveau neurologlyue d'un myéloméningocèle La liaison entre la race, le sexe et les niveaux neurologiques d'un myéloméningocèle a étéétudiée chez 251 patients. Globalement, le ratio blanc/noir était de 3,6 et le ratio homme/femme de 0,86. Cependant, la proportion de blancs et de femmes etait significativement plus forte pour le niveau dorsal (ratio blanchoir de 13,6, ratio homme/femme de 0,43), alors que les ratios étaient comparables à ceux de la population générale pour le niveau lombiaire. Il faut en conclure que le myéloméningocèle de niveau thoracique a une pathogénie différente de celui du niveau lombaire. ZUSAMMENFASSUNG Einfluβ von Rasse und Geschlecht auf den neurologischen Grad der Myelorneningocele Bei 251 Patienten wurde untersucht, ob es eine Beziehung von Rasse und Geschlecht zu den verschiedenen neurologischen Erscheinungsformen der Myelomeningocele gibt. Insgesamt betrug das Verhältnis weiß/schwarz 3·6 und das Verhältnis männlich/weiblich 0·86. Bei der thorkalen Myelomeingocele erhöhte sich jedoch der Anteil von weßen und weiblichen Patientn signifikant Verhältnis weiß/schwarz 3·6 und das Verhältnis männlich/weiblich 0·86. Bei der thorkalen Myelomeningocele erhöhte sich jedoch der Anteil von weißen und weiblichen Patienten signifikant (weiß/schwarz 13·6, männlich/weiblich 0·43), während bei den Patienten mit lumbaler Myelomeningocele die Verhältnisse von Geschlecht und Rasse der Verteilung in der Allgemeinpopulation entsprachen. Dies spricht für die Annahme, daß die thorakale Myelomeningocele eine andere Pathogenese hat als die lumbale. RESUMEN Efecto de la raza y el sexo sobre en nivel neurológico en el mielomeningocele La asociación de la raza y sexo con los diferentes niveles neurológicos e el mielomeningocele se estudió en 251 pacientes. En conjunto la relación blanco/legro era de 3·6 y la varodhembra estaba aumentada significativamente en los pacientes con nivel torácico (relación blanco/negro 13·6, y varón/hembra 0·43) mientras que los pacientes con nivel lumbar la relación de sexos y raza era equivalente a la de la población del area. Esto apoya la idea de que el nivel toracico del mielomeningocele tiene una patogenia diferente del nivel lumbar.
A sixteen-month-old child presented with cyanosis of the right arm. Investigation revealed bilateral persistent ductus arteriosus with isolation of the right subclavian artery from the aorta. Pulmonary vascular resistance and pulmonary arterial pressure were elevated so that the right subclavian artery received desaturated blood from the right pulmonary artery via the persistent right ductus arteriosus.
The effects of immersion on respiration of term lambs during the perinatal period were studied under various conditions. After consistent breathing had developed in the newborn animal, immersion of the entire animal, immersion of its head, or introduction of fluid retrogradely into the trachea produced very marked respiratory depression as determined by a pneumotachometer attached to a trachial airway. Less marked, but still significant, respiratory depression was noted in animals subjected to snout immersion and to immersion with the head kept above the water bath. In this latter group, warm water depressed breathing more than cool water. The inhibitory effect of immersion on the initiation of breathing was shown by lack of survival of intubated lambs delivered into a water bath.
ExtractIncreased activity of the carotid chemorecep tors from hypoxia and hypercarbia, induced by occlusion of the umbilical cord, has importance in initiating effective respiration of the term lamb. The state of hypoxia and hypercarbia continuing after birth should also evoke strong stimulation from the carotid glomi. The present experiments measure the effects on ventilation resulting from interruption of carotid chemoreceptor stimulation to the respiratory center by division of each carotid sinus nerve of the lamb during the newborn period.Ewes were given spinal anesthesia and each lamb was partly removed from the uterus to permit an operative approach through the neck. The carotid sinus nerves were exposed and tagged with loose threads to facilitate division of the nerve at a later stage. The lamb was then delivered, its umbilical cord clamped, and its inspiratory volume measured by pneumotachometric techniques.Each of the seven lambs studied was permitted to establish respiration before its first carotid sinus nerve was divided. The time intervals between birth and division of the first nerves varied from 5.5 to 38.5 minutes after birth. The second nerves were divided several minutes later when respiration had recovered from the effects of division of the first nerve. A significant fall in ventilation was observed within 50 seconds after division of each carotid sinus nerve. Improved ventilation began to occur in some animals 150 seconds later, and occurred in all animals within several minutes after division of each nerve. Levels of Pc>2> pH and PCO2 i n carotid artery blood before nerve division revealed hypoxia, hypercarbia and acidosis; this aberrant state became worse during the period of diminished ventilation. The minimal changes in heart rate and blood pressure resulting from interruption of baroreceptor fibers were insufficient to influence respiration. Speculation
Studies were performed to define the CNS acid-base status in the fetal lamb, as well as the contribution of CNS mechanisms in the initiation and control of breathing in the newly born lamb. The average CSF pH in term fetal lambs was found to be similar to that in young lambs as well as man. When fetal CSF hydrogen ion concentration was noted to be increased, or when perfusion of the ventral lateral medulla with mock CSF high in hydrogen ion concentration was carried out, no respiratory activity was noted. This suggests that the central response to hydrogen ion concentration, which is responsible for control of respiration in the breathing animal, may not be operative in the fetal state. However, in the physiologic setting of these experiments, the onset of breathing was primarily a central function which was little affected by peripheral chemoreceptor or baroreceptor discharge, as animals with their carotid sinus and vagal nerves divided initiated respiration as consistently as controls. Once breathing has been initiated, the central response to hypercarbic breathing could be demonstrated in the absence of any possible peripheral chemoreceptor influence.
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