A Model Analysis of Arterial Oxygen Desaturation during Apnea in Preterm Infants

Rapid arterial O2 desaturation during apnea in the preterm infant has obvious clinical implications but to date no adequate explanation for why it exists. Understanding the factors influencing the rate of arterial O2 desaturation during apnea () is complicated by the non-linear O2 dissociation curve, falling pulmonary O2 uptake, and by the fact that O2 desaturation is biphasic, exhibiting a rapid phase (stage 1) followed by a slower phase when severe desaturation develops (stage 2). Using a mathematical model incorporating pulmonary uptake dynamics, we found that elevated metabolic O2 consumption accelerates throughout the entire desaturation process. By contrast, the remaining factors have a restricted temporal influence: low pre-apneic alveolar causes an early onset of desaturation, but thereafter has little impact; reduced lung volume, hemoglobin content or cardiac output, accelerates during stage 1, and finally, total blood O2 capacity (blood volume and hemoglobin content) alone determines during stage 2. Preterm infants with elevated metabolic rate, respiratory depression, low lung volume, impaired cardiac reserve, anemia, or hypovolemia, are at risk for rapid and profound apneic hypoxemia. Our insights provide a basic physiological framework that may guide clinical interpretation and design of interventions for preventing sudden apneic hypoxemia

Apnea of prematurity: from cause to treatment

Apnea of prematurity (AOP) is a common problem affecting premature infants, likely secondary to a “physiologic” immaturity of respiratory control that may be exacerbated by neonatal disease. These include altered ventilatory responses to hypoxia, hypercapnia, and altered sleep states, while the roles of gastroesophageal reflux and anemia remain controversial. Standard clinical management of the obstructive subtype of AOP includes prone positioning and continuous positive or nasal intermittent positive pressure ventilation to prevent pharyngeal collapse and alveolar atelectasis, while methylxanthine therapy is a mainstay of treatment of central apnea by stimulating the central nervous system and respiratory muscle function. Other therapies, including kangaroo care, red blood cell transfusions, and CO2 inhalation, require further study. The physiology and pathophysiology behind AOP are discussed, including the laryngeal chemoreflex and sensitivity to inhibitory neurotransmitters, as are the mechanisms by which different therapies may work and the potential long-term neurodevelopmental consequences of AOP and its treatment

Congenital Diaphragmatic hernia – a review

Congenital Diaphragmatic hernia (CDH) is a condition characterized by a defect in the diaphragm leading to protrusion of abdominal contents into the thoracic cavity interfering with normal development of the lungs. The defect may range from a small aperture in the posterior muscle rim to complete absence of diaphragm. The pathophysiology of CDH is a combination of lung hypoplasia and immaturity associated with persistent pulmonary hypertension of newborn (PPHN) and cardiac dysfunction. Prenatal assessment of lung to head ratio (LHR) and position of the liver by ultrasound are used to diagnose and predict outcomes. Delivery of infants with CDH is recommended close to term gestation. Immediate management at birth includes bowel decompression, avoidance of mask ventilation and endotracheal tube placement if required. The main focus of management includes gentle ventilation, hemodynamic monitoring and treatment of pulmonary hypertension followed by surgery. Although inhaled nitric oxide is not approved by FDA for the treatment of PPHN induced by CDH, it is commonly used. Extracorporeal membrane oxygenation (ECMO) is typically considered after failure of conventional medical management for infants ≥ 34 weeks’ gestation or with weight >2 kg with CDH and no associated major lethal anomalies. Multiple factors such as prematurity, associated abnormalities, severity of PPHN, type of repair and need for ECMO can affect the survival of an infant with CDH. With advances in the management of CDH, the overall survival has improved and has been reported to be 70-90% in non-ECMO infants and up to 50% in infants who undergo ECMO

Exploring the Uranyl Organometallic Chemistry: From Single to Double Uranium-Carbon Bonds

International audienc

Exploring the Uranyl Organometallic Chemistry: From Single to Double Uranium-Carbon Bonds

International audienc

Easy access to uranium nucleophilic carbene complexes (pub)

International audienc

Estimations des doses dans le cadre d’une étude comparative des voies radiales et fémorales droites dans la technique radiologique coronarographique

L’irradiation des patients et de l’opérateur au cours de coronarographie et/ou angioplastie coronaire, fait désormais partie des préoccupations légitimes de la cardiologie interventionnelle moderne. Les voies fémorales et radiales droites sont les voies d’accès privilégiées pour la réalisation de ces examens. Néanmoins, peu de registres comparent ces 2 voies d’abord en terme d’irradiation du patient et de l’opérateur. L’objectif de ce registre est une évaluation comparative de ces 2 techniques. 423 patients consécutifs ayant bénéficié dans notre centre de l’une ou l’autre de ces techniques réalisées entre octobre 2005 et mars 2006 ont été inclus. Les paramètres retenus sont les suivants : dose bras gauche opérateur, produit dose × surface pour le patient, temps global des procédures et durée de la scopie. Pour les 4 paramètres étudiés, les résultats sont significativement supérieurs en cas de coronarographie et coronarographie plus angioplastie ad hoc par voie radiale que par voie fémorale. Respectivement : (1) temps de scopie : 4 min versus 1,8 min, et 9,6 min versus 6,3 min ; (2) temps de procédure : 15 min versus 9,5, et 41 min versus 35,25 min ; (3) dose patient : 59 Gy cm2 versus 37,5 Gy cm2, et 123 Gy cm2 versus 102 Gy cm2 ; (4) dose opérateur : 29 µSv versus 13 µSv, et 69 µSv versus 40 µSv. Malgré son intérêt en terme d’économie de complication de voie d’abord, la voie radiale droite est significativement plus irradiante pour les patients et les opérateurs que la voie fémorale droite

Uranium(IV) Nucleophilic Carbene Complexes

International audienc