[Enoxaparin and tinzaparin in pediatrics: Impact of recommendation on prescription quality and anti-Xa levels]. / Énoxaparine et tinzaparine en pédiatrie : impact de recommandations sur la qualité des prescriptions et l'activité anti-Xa.

OBJECTIVES: A protocol has been written and distributed in May 2017 to all prescribers in a pediatric hospital to standardize and to secure the prescriptions of enoxaparin and tinzaparin considered as two high risk medications. The aim of this study is to evaluate the impact of the protocol on those prescriptions in a pediatric population. METHODS: This is a monocentric retrospective study comparing prescriptions of this two low-molecular-weight heparins for patients under 18 years old in 2016 and 2018, thus before and after the protocol redaction. RESULTS: In 2016, 2246 prescriptions of enoxaparin and tinzaparin were analyzed for 627 patients. Among them, 142 (22.6%) patients have had at least one anti-Xa level dosed. On the other hand, in 2018, 2061 prescriptions were written for 628 patients including 96 (15.3%) who have had at least one anti-Xa level dosed. The conformity rate of the first dose in IU/kg/administration of the first enoxaparin prescription goes from 36.3% before protocol to 52.1% after (P=0.03*). Concerning tinzaparin, the conformity rate goes from 69.2% to 83.3%. (P=0.19). The rate of first anti-Xa level in the range 0.4 to 1.2 IU/ml increase between 2016 and 2018 from 27.7% to 43.8% (P<0.001*). CONCLUSION: This protocol enabled to improve the quality of prescriptions in terms of: dosage written in IU/kg/administration, frequency of administration, dilution conformity, and result of the first anti-Xa level. Some efforts must be made in writing the dose in IU not in mg or ml.

[Atrioventricular block after transcatheter atrial septal defect closure using the Amplatzer septal occluder(®)]. / Bloc auriculo-ventriculaire après fermeture d'une communication interauriculaire avec un système Amplatzer septal occluder(®)

Transcatheter closure of atrial septal defect (ASD) in children is now an accepted treatment as an alternative to surgery. We report a case of complete atrioventricular block (AVB) observed over several days after closure of an ASD with an Amplatzer Septal Occluder(®) in a 13-year-old child. The spontaneous outcome was good with regression of the complete AVB, but 1 year later, a first-degree AVB was still present. The use of large devices in young children and a small postero-inferior rim seem to be risk factors of AVB. Transcatheter closure of ASD requires close monitoring of cardiac rhythm.

[Evolution of prenatal diagnosis of congenital heart diseases in Indre-et-Loire (France) over a period of 15 years]. / Évolution du diagnostic anténatal des cardiopathies congénitales entre 1991 et 2005 dans une population limitée au département d'Indre-et-Loire.

UNLABELLED: The value of prenatal diagnosis of major congenital heart diseases (CHDs) has already been proved. In this study, we observed the evolution of the detection rate of CHDs and the quality of the diagnoses over a 15-year period in the Indre-et-Loire department of France. METHOD: Retrospective analysis of the quantitative and qualitative data of prenatal diagnosis between 2000 and 2005 (period 3) and comparison with studies conducted from 1991 to 1994 (period 1) and from 1995 to 1999 (period 2). The CHDs considered to be detectable are the major CHDs with neonatal symptoms. In order to analyze the quality of prenatal diagnosis, each diagnosis was classified as correct, false, or incomplete during period 3. RESULTS: Period 3: 65.7% detectable CHDs were screened. Using period 1 criteria for prenatal diagnosis, the percentage of CHDs detected for periods 1, 2, and 3 was 43.2, 66.7, and 78%, respectively. Between periods 2 and 3, the detection rate increased from 52 to 74% for CHDs diagnosed with the visualization of the outflow tract. It increased from 63 to 71% for CHDs diagnosed with a four-chamber view. During period 3, diagnoses made by a pediatric cardiologist were correct and complete in 80% of cases. It was less than 25% otherwise. CONCLUSION: The improvement of prenatal diagnosis over time results from technological progress, the greater experience of ultrasonographers, and the systematic visualization of the outflow tract in addition to the four-chamber view. Despite the improvement in prenatal diagnosis, one-third of major CHDs were not screened before birth. Pediatricians still need to diagnose CHDs after birth.

Direct measurement of power during one single sprint on treadmill.

We tested the validity of an instrumented treadmill dynamometer for measuring maximal propulsive power during sprint running, and sought to verify whether this could be done over one single sprint, as shown during sprint cycling. The treadmill dynamometer modified towards sprint use (constant motor torque) allows vertical and horizontal forces to be measured at the same location as velocity, i.e. at the foot, which is novel compared to existing methods in which power is computed as the product of belt velocity and horizontal force measured by transducers placed in the tethering system. Twelve males performed 6s sprints against default, high and low loads set from the motor torque necessary to overcome the friction due to subjects' weight on the belt (default load), and 20% higher and lower motor torque values. Horizontal ground reaction force, belt velocity, propulsive power and linear force-velocity relationships were compared between the default load condition and when taking all conditions together. Force and velocity traces and values were reproducible and consistent with the literature, and no significant difference was found between maximal power and force-velocity relationships obtained in the default load condition only vs. adding data from all conditions. The presented method allows one to measure maximal propulsive power and calculate linear force-velocity relationships from one single sprint data. The main novelties are that both force and velocity are measured at the same location, and that instantaneous values are averaged over one contact period, and not over a constant arbitrary time-window.

[Enzyme replacement therapy in a boy with infantile Pompe disease: cardiac follow-up]. / Enzymothérapie substitutive chez un nourrisson atteint de maladie de Pompe : évolution cardiologique.

Pompe disease is an autosomal recessive glycogen storage disorder caused by acid-alpha-glucosidase deficiency. The infantile form is usually fatal by 1 year of age in the absence of specific therapy. We report the cardiac follow-up of a 4-month-old boy treated with enzyme replacement therapy (ERT) for 8 months. The patient had no cardiac failure at the age of 1 year. Before starting ERT, ECG showed a shortened PR interval, with huge QRS complexes and biventricular hypertrophy; echocardiography demonstrated major hypertrophic cardiomyopathy. The QRS voltage (SV1+RV6) decreased from 13 to 2.9 mV after 32 weeks of ERT, suggesting a progressive reduction of cardiac hypertrophy and intracellular glycogen excess. The PR interval increased from 60 to 90 ms. A block of the right bundle branch appeared after 13 weeks of treatment. The indexed left ventricular mass decreased from 240 to 90 g/m2 after 30 weeks of ERT. The left ventricular ejection fraction decreased transitorily between the 5th and the 15 th weeks of treatment. In summary, ERT is an efficient therapeutic approach for the cardiomyopathy of infantile Pompe disease. However, the possible occurrence of a right bundle branch block and a transitory alteration in the ejection fraction highlight the importance of cardiac follow-up.

A system to simulate gas exchange in humans to control quality of metabolic measurements.

We have developed a gas exchange simulation system (GESS) to assess the quality control in measurements of metabolic gas exchange. The GESS simulates human breathing from rest to maximal exercise. It approximates breath-by-breath waveforms, ventilatory output, gas concentrations, temperature and humidity during inspiration and expiration. A programmable motion control driving two syringes allows the ventilation to be set at any tidal volume (VT), respiratory frequency (f), flow waveform and period of inspiration and expiration. The GESS was tested at various combinations of VT (0.5-2.51) and f(10-60 stroke x min(-1)) and at various fractional concentrations of expired oxygen (0.1294-0.1795); and carbon dioxide (0.0210-0.0690) for a pre-set flow waveform and for expired gases at the same temperature and humidity as room air. Expired gases were collected in a polyethylene bag for measurement of volume and gas concentrations. Accuracy was assessed by calculating the absolute and relative errors on parameters (error=measured-predicted). The overall error in the gas exchange values averaged less than 2% for oxygen uptake and carbon dioxide output, which is within the accuracy of the Douglas bag method.

Validity of oxygen uptake measurements during exercise under moderate hyperoxia.

PURPOSE: The validity of oxygen uptake in hyperoxia (FIO2 = 30%) measured by an automated system (MedGraphics, CPX/D system) was assessed during the simulation of gas exchanges during exercise with a mechanical system and during submaximal exercise by human subjects. METHODS: The simulation system reproduced a stable and accurate VO2 for 30 min (sim-test). This trial was repeated nine times in normoxia and nine times in hyperoxia. Ten subjects also performed two submaximal exercises (55% of normoxic VO2max) on a cycle ergometer at the same absolute power in normoxia and in hyperoxia (ex-test). RESULTS: There was a significant downward drift of the oxygen fraction measurement in hyperoxia (< or = 0.10% for FIO2 and FEO2) during sim-test, but VO2 measurement remained stable in the two conditions. There was also a downward drift of the oxygen fraction measurement in the two conditions (< or = 0.07% for FIO2) during ex-test. VO2 was significantly higher in hyperoxia (+4.6%), and this result was confirmed using a modified Douglas bag method. CONCLUSIONS: These findings show that the CPX/D system is stable and valid for assessing VO2 in moderate hyperoxia.

Modeling of adaptations to physical training by using a recursive least squares algorithm.

The present study assesses the usefulness of a systems model with time-varying parameters for describing the responses of physical performance to training. Data for two subjects who undertook a 14-wk training on a cycle ergometer were used to test the proposed model, and the results were compared with a model with time-invariant parameters. Two 4-wk periods of intensive training were separated by a 2-wk period of reduced training and followed by a 4-wk period of reduced training. The systems input ascribed to the training doses was made up of interval exercises and computed in arbitrary units. The systems output was evaluated one to five times per week by using the endurance time at a constant workload. The time-invariant parameters were fitted from actual performances by using the least squares method. The time-varying parameters were fitted by using a recursive least squares algorithm. The coefficients of determination r2 were 0.875 and 0.879 for the two subjects using the time-varying model, higher than the values of 0.682 and 0.666, respectively, obtained with the time-invariant model. The variations over time in the model parameters resulting from the expected reduction in the residuals appeared generally to account for changes in responses to training. Such a model would be useful for investigating the underlying mechanisms of adaptation and fatigue.

Increase in occlusion pressure with ventilation and response to maximal exercise.

Fifteen sedentary or mildly active men (low fit group) and 15 trained male athletes (high fit group) performed an incremental exercise bout on a cycle ergometer until exhaustion. At each submaximal load, minute ventilation (VE) and rate of change of mouth pressure (dP/dt) during a brief airway occlusion were computed. The airway was occluded for 40-200 ms and adjusted according to the level of ventilation. Maximal oxygen uptake (VO2peak) and minute ventilation (VEpeak) were measured during the last increment. dP/dt was related to VE in all subjects as dP/dt = a VECURV. The CURV parameter was 0.99-1.95 with a median of 1.49. The subjects were divided into four groups of seven or eight according to their physical fitness and their CURV value. Low and high CURV subjects had a CURV below and above the median, respectively. VE/VO2peak and VE/VCO2peak were significantly higher in the low CURV than in the high CURV group (P < 0.01 and P < 0.05, respectively). Although factors other than the increase in pulmonary impedance with ventilation may influence CURV, the present results indicate the possible influence of mechanical constraint of breathing on the ventilatory output.

Optic fibre as a transducer of tendomuscular forces.

Direct in vivo tendon force measurements open up new possibilities for understanding of muscle-tendon loads during natural locomotion. The present report presents a new optic fibre method for such applications. The method is based on light intensity modulation by mechanical modification of the geometric properties of the optic fibre. A special optic fibre with a plastic covering buffer and with a total diameter of either 265 microns or 500 microns was carefully prepared at both ends for receiving and transmitting light. The fibre was inserted through the rabbit common calcaneal tendon with a 20 gauge needle. By removing the needle the optic fibre remained in situ. Static loading demonstrated that the voltage output of the optic fibre transducer showed a good linear fit of r = .999 with added loads. In dynamic loading conditions the optic fibre followed well the response of a strain gauge transducer, which was also attached to the tendon. The optic fibre method seems suitable for many applications for tensile and possibly ligament force measurements.

Comparison of incremental and steady state tests of endurance training.

To compare the results obtained by incremental or constant work load exercises in the evaluation of endurance conditioning, a 20-week training programme was performed by 9 healthy human subjects on the bicycle ergometer for 1 h a day, 4 days a week, at 70-80% VO2max. Before and at the end of the training programme, (1) the blood lactate response to a progressive incremental exercise (18 W increments every 2nd min until exhaustion) was used to determine the aerobic and anaerobic thresholds (AeT and AnT respectively). On a different day, (2) blood lactate concentrations were measured during two sessions of constant work load exercises of 20 min duration corresponding to the relative intensities of AeT (1st session) and AnT (2nd session) levels obtained before training. A muscle biopsy was obtained from vastus lateralis at the end of these sessions to determine muscle lactate. AeT and AnT, when expressed as % VO2max, increased with training by 17% (p less than 0.01) and 9% (p less than 0.05) respectively. Constant workload exercise performed at AeT intensity was linked before training (60% VO2max) to a blood lactate steady state (4.8 +/- 1.4 mmol.l-1) whereas, after training, AeT intensity (73% VO2max) led to a blood lactate accumulation of up to 6.6 +/- 1.7 mmol.l-1 without significant modification of muscle lactate (7.6 +/- 3.1 and 8.2 +/- 2.8 mmol.kg-1 wet weight respectively). It is concluded that increase in AeT with training may reflect transient changes linked to lower early blood lactate accumulation during incremental exercise.(ABSTRACT TRUNCATED AT 250 WORDS)