Thermal acclimation of neonates to prolonged cool exposure as regards sleep stages

The thermal responses of neonates during a cool acclimation period were studied with regard to sleep stages. Sleep stages, body temperatures and metabolic rate (VO2) were studied for seven neonates nursed in incubators and exposed to a cool temperature (thermoneutrality minus 2 degrees C) for 75 h. Each recording session lasted 3 h in the morning: firstly under thermoneutral baseline conditions, then during the first and last 3-h periods of the cool acclimation and finally during the last 3 h of a 24-h recovery period. Sleep structure was modified during the initial hours of cool exposure: the percentage of active sleep increased (AS: +13%, P = 0.028) at the expense of quiet sleep (QS: -11%, P = 0.043). This alteration in sleep structure persisted at the end of the acclimation period. Metabolic heat production only increased in the later period of cool acclimation. Throughout the cool exposure, VO2 increased more (P = 0.040) in QS (+33%) than in AS (+20%) so that by the end of the cool period, VO2 levels were similar in both sleep stages. During cool acclimation, the maintenance of homeothermy is related not only to a change in sleep organization but also to modifications in the thermoregulatory processes in both sleep stages. Considering the importance of AS/QS patterns in the neurobehavioral development of neonates, the present results could have clinical implications for the thermal management of neonates.     

Parvovirus B19 thrombocytopenic purpura complicated with a cerebral hemorrhage]

Severe hemorrhage complications are rare in idiopathic thrombocytopenic purpura. This pathology is often considered as benign. CASE REPORT: We report the case of a four-year-old boy presenting a parvovirus B19 idiopathic thrombocytopenic purpura. Despite early and repeated use of intravenous immunoglobulin, the evolution was characterized by the secondary apparition of a cerebral hemorrhage. It was lethal seven days after the initial diagnosis. CONCLUSION: Parvovirus B19 should be investigated as an etiologic agent of idiopathic thrombocytopenic purpura, using PCR. The unpredictive aspect of severe hemorrhage complications, especially cerebral hemorrhages, explains the potential severity of this disease.     

Sequential updating of a new dynamic pharmacokinetic model for caffeine in premature neonates

BACKGROUND AND OBJECTIVE: Caffeine treatment is widely used in nursing care to reduce the risk of apnoea in premature neonates. To check the therapeutic efficacy of the treatment against apnoea, caffeine concentration in blood is an important indicator. The present study was aimed at building a pharmacokinetic model as a basis for a medical decision support tool. METHODS: In the proposed model, time dependence of physiological parameters is introduced to describe rapid growth of neonates. To take into account the large variability in the population, the pharmacokinetic model is embedded in a population structure. The whole model is inferred within a Bayesian framework. To update caffeine concentration predictions as data of an incoming patient are collected, we propose a fast method that can be used in a medical context. This involves the sequential updating of model parameters (at individual and population levels) via a stochastic particle algorithm. RESULTS: Our model provides better predictions than the ones obtained with models previously published. We show, through an example, that sequential updating improves predictions of caffeine concentration in blood (reduce bias and length of credibility intervals). The update of the pharmacokinetic model using body mass and caffeine concentration data is studied. It shows how informative caffeine concentration data are in contrast to body mass data. CONCLUSION: This study provides the methodological basis to predict caffeine concentration in blood, after a given treatment if data are collected on the treated neonate.     

Peripheral chemoreceptor activity in sleeping neonates exposed to warm environments.

In neonates, it is often assumed that ventilatory control and heat stress interact. Thus the two factors have been implicated in various pathologies (apnoea, sudden infant death syndrome). However, little is known about the mechanisms of this interaction, and the influence of sleep is still debated. This study aimed at determining the influence of warm exposure on the decrease in ventilation during a hyperoxic test (HT), which is considered to be a measure of peripheral chemoreceptor activity. The test was performed in active (AS) and quiet sleep (QS) in 12 neonates exposed to thermoneutral or warm environments. The HT consisted of 30 s of inspired, 100% O(2). The ventilatory response was assessed in terms of a response time, defined as the time elapsing between HT onset and the first significant change in V(E). Our results show that, in both thermal conditions, the fall in V(E) was higher in AS than in QS. Warm exposure significantly enhanced the ventilatory response in AS (-27.5 +/- 8.7% vs. -38.3 +/- 8.8%, P < 0.01) but not in QS. A thermometabolic drive or inputs from thermoreceptors could be involved in the reinforcement of peripheral chemoreceptor activity in AS in warmer environments, which could contribute to an increasing risk of apnoea in neonates with altered chemoreceptor function. Since hypothalamic structures are involved in thermoregulatory, sleep processes and (probably) in respiratory control, it could well be the principal site where this interaction occurs.     

Central catheters and pericardial effusion: results of a multicentric retrospective study]

OBJECTIVE: To evaluate the use of neonatal central venous catheters (CVC) in 38 french neonatal units and occurrence of pericardial effusion (PCE) over the past 5 years. MATERIALS AND METHODS: We surveyed 38 units with a questionnaire and studied the cases of PCE in five units. RESULTS: Response rate was 89% (34/38). Accepted CVC tip positions were: junction of right atrium (RA) and vena cava (VC) 76%, VC 58%, RA 11%. Fifty percent of the centers had been exposed to PCE. 16 cases of PCE were studied. Median gestational age was 31 weeks (range: 26.1 to 40 weeks). Median time from insertion: 3.2 days (range: 0.4-13.5). In all cases CVC tip was intracardiac at insertion with inadequate withdrawing in 13 cases. Sudden cardiac collapse was reported in eight cases, and unexplained cardiorespiratory instability in six cases. Echography showed PCE in 14 cases. One diagnosis was post-mortem. CVC was withdrawn in 12 patients and 13 underwent pericardiocentesis. Four patients died and two had neurological sequelae. CONCLUSION: PCE was associated with intracardiac CVC tip. The CVC tip should be controlled with radiography or echography outside the cardiac silhouette. PCE diagnosis must be considered in face of unexplained cardiovascular decompensation of neonate with CVC.     

Extravasation of calcium solution in the child: Value of negative-pressure wound therapy

The extravasation of a calcium solution into soft tissue constitutes a medical emergency, and a lack of adequate management can lead to significant functional and cosmetic sequelae. Here, we report on the management of and long-term outcome in two children who experienced calcium infusion leakage. We also describe the emergency procedures used in cases of extravasation and discuss the role of negative pressure wound therapy as an appropriate adjunct to conventional techniques for dealing with serious extravasation-related injuries.