A new genetic variant causing auditory neuropathy: A CARE case report

INTRODUCTION

Auditory neuropathy refers to impaired synchronization of the auditory signal along the cochlear nerve. The present study, following CARE case report guidelines, describes a case of auditory neuropathy secondary to a genetic variant not previously described.

OBSERVATION

An 18-year-old patient was followed for multiple learning disorder. His main complaint was speech comprehension, especially in noise. Auditory neuropathy was diagnosed on electrophysiological criteria, linked to a 2.66Mb deletion on the short arm of chromosome 16, at 16p13.11p12.3 (15,492,317-18,162,167, according to the hg19 version of the human reference genome). Adapted speech therapy sessions with auditory training for intelligibility in noise and a hearing aid with high-frequency microphone were prescribed. At 6months, the patient reported improvement in understanding speech in noise.

CONCLUSION

The involvement of this 16p13.11 deletion in the patient's symptomatology was not obvious, in a probable context of incomplete penetrance and variable expression. Early diagnosis of auditory neuropathy allowed implementation of better adapted multidisciplinary specialized management.

Prise en charge de la fièvre de l'enfant: les connaissances et pratiques des parents sont-elles satisfaisantes?

Paediatric fever is a frequent reason of consulting a paediatrician or a general practitioner (30% of paediatric consultations).

AIM OF THE STUDY

This investigation aimed at reporting the knowledge level concerning child's and infant's fever in a urban population and the resulting practices. Two thousand and six hundred questionnaires were distributed in June 2004 in the 29 scholar institutions of Metz agglomeration (France) classified in 3 categories according to socio-economical conditions of parents: 3 institutions of city centre (high socioeconomical conditions), 18 sub-urban institutions (intermediary conditions) and 8 institutions located in priority education zones (ZEP) (defavorable conditions).

RESULTS

One thousand and thirty-eight questionnaires could be analyzed (40%): 176 in city centre, 634 in sub-urban zones and 228 in ZEP. Fever threshold at 38 degrees C is well-known and fever measuring methods used are mostly in accordance with the recommendations. The best room temperature was known and the use of antipyretic physical means underlined only a few cases of obvious mistakes. All parents were informed about worrying signs related with fever even if doctor's resort was excessive. Acetaminophen was the reference molecule before ibuprofen whereas the use of aspirin was decreasing. Antipyretic treatments methods used by parents were often unsuitable, leading to therapeutical inefficacy, overdosage or noxious drug interactions, mainly because of a lack of knowledge about drug components.

CONCLUSION

This investigation underlines insufficient knowledge and noxious management practices among parents with unfavourable socio-economical conditions which lead us to recommend targeted information preferentially in areas gathering together most unfavourable socio-economical condition populations.

[Paediatric cardiac surgery and autoevaluation: risk score, complexity score and graphic analysis]

The creation of a paediatric surgical unit requires autoevaluation in order to: assess the quality of the results with respect to recognised international standards, answer the family's questions about the results obtained and adhere to criteria of accreditation Between January 2003 and December 2004, 201 consecutive patients, children (N= 164) or operated for adult congenital heart disease (N= 37) were treated. No patient was excluded. The RACHS-1 risk score, the ARISTOTLE scores of complexity and performance and the CUSUM and VLAD graphic analyses were applied to the study of hospital mortality. An original "variable performance-adjusted display" (VPAD) graphic analysis was performed to show up any possible variations of performance. Paediatric hospital survival was 97.56% (95% CI: 93.9 - 99.1). The paediatric complexity and performance scores were 6.79 +/- 0.22 and 6.62 respectively. In the absence of statistical significance in this field of autoevaluation, graphic analyses indicated the performance of our unit with no "learning" curves. Graphic scores and analyses allow assessment of the function of a paediatric cardiac surgical unit and the variations of complexity with respect to time, before the appearance of statistical significance. The ARISTOTLE complexity and performance scores and their adaptation in VPAD seem to be more reliable and discriminating than the RACHS-1 score.

[Complications of prostaglandin E1 treatment of congenital heart disease in paediatric medical intensive care]

The authors undertook a retrospective study of the modes of prescription, the tolerance and efficacy of prostaglandin E1 in 62 consecutive neonates with congenital heart disease (average Age 1.6 days: 35 boys: weight: 3.1 +/- 0.6 Kg) admitted to the paediatric intensive care unit of Nancy University Hospital between 1998 and 2002. The infusion time and cumulative dosage were 134 +/- 112 (6-480) hours and 111 +/- 94 (4-396) microg/Kg respectively. The side effects that were observed were: Apnoea (19%), abdominal distension (16%), bradycardia (13%), enterocolitis (6.5%), hypotension (6.5%), vomiting (5%), fever (1.6%) and skin rash (1.6%). Gastrointestinal disturbances are associated with a low body weight (p<0.04), to prolonged treatment (p<0.02) with no influence of initial or cumulative dosages (P=NS), with respiratory assistance (p<0.03) and longer hospital stay (p<0.01). Hypotension was commoner in cases of poor neonatal adaptation. Mortality was correlated with severe initial acidosis (p<0.02), a low Apgar score, the initial prolonged use of high doses of prostaglandin (p<0.04), and the presence of severe valvular aortic stenosis or hypoplasia of the left heart (p<0.002). The authors conclude that treatment with prostaglandin is effective in the majority of cases despite the use of low maintenance doses (0.01 microg/Kg/min). Gastrointestinal disturbances favourised by the perinatal context, the cardiac disease, and prolonged treatment are significant factors for morbidity and mortality. The beneficial role of early neonatal enteral feeding was not demonstrated in this high risk population.

[Kawasaki disease in newborns and infants: refractory forms to immunoglobulin therapy]

We studied 52 consecutive patients with Kawasaki disease hospitalized (1984 -2003) during the acute phase (mean age 2.5 + 2.4 years; range 0.3 to 16 years, 34 males, 18 cases with coronary aneurysms, median follow-up 6.7 years), and identified a subgroup presenting a refractory subtype to immunoglobulin therapy.

RESULTS

forty-nine infants benefited from a first regimen of immunoglobulins, 8.4 + 6 days following the onset of symptoms. Eleven infants (1.4 + 1.2 years, range 0.3 - 4.3 years, median 1.7 years) were non-responders, with coronary aneurysms in 8 cases (giant aneurysms (>8 mm) in 4 cases). These 11 infants were treated a second time by immunoglobulins, but 6 cases (1.8 + 1.6 years, with two cases of severe ventricular dysfunction and 2 cases of fatal myocardial infarction) required an additive therapy with (oral or IV route) corticosteroids (2) and cyclophosphamide bolus (4) with or without repetitive plasmapheresis (4). Non-responder patients had their treatment onset later (p<0.0003) using higher dosages (p<0.005), a longer delay for fever or biological signs correction (p<0.02), a worsening of coronary lesions (p<0.05) with more coronary secondary aneurysms (p<.005). The aneurysms, more frequent at the second phase of the disease (p<0.0001) are associated with: a younger age (p<0.03), a lower weight (p<0.02), a later onset of treatment (p<0.03), prolonged fever or inflammatory syndrome (p<0.05), higher level of fibrinogene (p<0.02). The overall mortality (5.7%) is correlated with giant aneurysms (p<0.001), myocardial ischemia (p<0.0001), heart failure (p<0.0001), and lack of early response to treatment (p<0.003).

CONCLUSION

immunoglobin therapy can be repeated. In case of severe forms, the use of corticosteroids, cyclophosphamide and plasmapheresis may be proposed.

[Domiciliary assisted ventilation in children]

The concept of assisted ventilation in the home setting has greatly progressed as a routine practice. This technique was used from 1990 to 2000 in 16 children cared for at our center. Ten children had neuromuscular disease (infantile spinal amyotrophy 6, Duchenne myopathy 3, and mitochondrial myopathy 1) or other conditions including central hypoventilation (n = 2), traumatic tetraplegia (n = 2), encephalopathy with chronic bronchitis (n = 1) and bronchopulmonary dysplasia (n = 1). Only 5 children had a tracheotomy, the others were treated successfully with non-invasive ventilatory assistance. Initialization of non-invasive ventilatory assistance had been planned before development of respiratory failure in 4 of the 11 children, but generally was indicated after an episode of acute respiratory distress. Home ventilation, particularly with non-invasive assistance is a reliable method for long-term treatment of chronic alveolar hypoventilation in children. The appropriate time for initiating this therapy should be better defined.

Methacholine-induced volume dependence of respiratory resistance in preschool children

Enhanced negative volume dependence of airway resistance is associated with bronchoconstriction in tracheostomized paralysed open-chest animals. Significant upper airways responses may be associated with bronchoconstriction and could thereby alter the pattern of volume dependence in spontaneously breathing subjects. The aim of the study was to test whether volume dependence of respiratory resistance (Rrs) could be demonstrated in preschool children undergoing routine methacholine challenge. The volume dependence of respiratory oscillation resistance at 12 and 20 Hz (Rrs,12 and Rrs,20) was examined in eight 4-5.5-yr-old children showing a positive response to methacholine. Multiple linear regression analysis was also used to account for flow dependence during tidal breathing (Rrs,12 or Rrs,20=K1+K2¿V'¿+K3V). Rrs,12 and Rrs,20 yielded similar results. Negative volume dependence was present at baseline and significantly enhanced by methacholine (p<0.01). For instance, the mean+/-SD inspiratory K3 at 20 Hz was 4.1+/-1.3 hPa x s x L(-2) at baseline and -15.0+/-4.3 hPa x s x L(-2) after methacholine, in which case it was also larger on expiration than on inspiration (p<0.05), possibly as a result of upper airway responses. A significant increase in the negative volume dependence of respiratory resistance may thus be shown in preschool children in response to methacholine. The volume dependence (K3) during inspiration may be particularly useful in detecting bronchoconstriction, because it is less likely to be affected by upper airway mechanisms than during expiration.

Effect of increased brain GABA concentrations on breathing in unanesthetized newborn rabbits

Evidence suggests that gamma-aminobutyric acid (GABA) is involved in control of breathing and in the hypoxia-related ventilatory depression in newborns. However, this evidence is obtained mainly from studies on anesthetized animals. Because anesthesia may interfere with the GABA system, the objectives of our study were to examine effects of GABA on ventilation (V(E)) and ventilatory response to hypoxia and to reveal effects of repeated hypoxia on GABA concentrations in unanesthetized newborns. The study was performed in rabbits in two age groups: 1-3 days old (group I) and 10-14 days old (group II). To increase brain endogenous GABA concentrations, rabbits were injected with an inhibitor of GABA transaminase, aminooxyacetic acid (AOAA; 20 mg/kg i.p.). To prevent postmortem formation of GABA, at the end of experiments the rabbits received an inhibitor of glutamic acid decarboxylase, IP-3-mercaptopropionic acid (100 mg/kg i.p.). Animals were studied in normoxia alone, or they were exposed for 15 min to 8% O(2) before and 10 and 35 min after saline or AOAA. GABA concentrations were measured in brainstem, cerebrum, and cerebellum by means of a capillary electrophoresis. In group I, AOAA had no respiratory effects. In group II, AOAA decreased V(E), tidal volume, and mean inspiratory flow in normoxia and reversed V(E) decline during hypoxia 10 min after the injection, GABA concentrations were not age dependent and the highest in the brainstem. Repeated hypoxia increased the cerebellar GABA concentrations and had no effect in group I. These results imply that in unanesthetized rabbits, GABAergic neurotransmission in the respiratory control network becomes functional by the 2nd week of life, but it does not contribute to the biphasic ventilatory response to moderate hypoxia. In contrast, GABA-evoked block of the cerebellar inhibitory input during hypoxia may be responsible for the reversal of the V(E) decline in unanesthetized newborns.

Sequential activation of activator protein-1-related transcription factors and JNK protein kinases may contribute to apoptotic death induced by transient hypoxia in developing brain neurons

Previous studies have demonstrated that transient hypoxia (6 h) induces apoptotic death in cultured neurons isolated from the fetal rat forebrain. Since activation of c-Jun N-terminal kinases (JNKs) and subsequent phosphorylation of c-Jun are suspected to be involved in the apoptotic pathway in several cell types, the time course of activator protein-1 (AP-1) DNA-binding, in line with induction of the AP-1 components and JNK activation, was examined during hypoxia/reoxygenation in the same model. Gel shift analysis depicted the presence of functional AP-1 transcription factors in both control and hypoxic neurons. One hour after the onset of hypoxia, all AP-1 components were markedly overexpressed. They include c-Jun, Jun B, Jun D, c-Fos and Fos-related antigens. Whereas, only c-Jun remained elevated for up to 96 h post-reoxygenation, time at which neurons were injured, other gene products showed patterned induction/repression as hypoxia progressed and then during the post-reoxygenation period, with Fos-related antigens being finally induced at 96 h. Only JNK1 was constitutively detected in cultured neurons, and its expression was inhibited during hypoxia. Nonetheless, both JNK1 and JNK3 were markedly, but transiently, induced at 48 h post-reoxygenation, when apoptosis-related morphological features became apparent. These data support the hypothesis that transient hypoxia, independently of ischemia, may trigger apoptosis through JNK signaling pathway in developing brain neurons.

[Diagnosis of post-operative venous thrombosis using determination of plasma D-dimer]

PURPOSE

The D-Dimer test has been shown to be highly sensitive for the diagnosis of deep vein thrombosis (DVT) and pulmonary embolism. Two automatic quantitative tests giving a rapid response within 10 and 30 minutes have been recently marketed. In the postsurgery situation however, the role of the D-Dimer test remains controversial and the optimal cutoff value remains open. The aim of this study was to determine the cutoff value during the postoperative period.

PATIENTS AND METHODS

One hundred three consecutive patients admitted to surgery were included. In all patients, D-Dimer test was performed every 2 or 4 days from admission to hospital discharge. The Vidas D-Dimer (Biomerieux, Marcy l'Etoile, France) and the STA Liatest D-DI (Diagnostica Stago, Asnières, France) were performed in parallel in all cases.

RESULTS

Thirty-five patients were excluded because the follow-up period was too short. Results suggest that a D-Dimer value below 2 micrograms/ml has a negative predictive value of 100%. A D-Dimer value over 4 micrograms/ml would indicate suspected deep vein thrombosis in half of the cases, even without clinical signs. Dividing the patients into three groups according to the D-Dimer value, the two tests correlated poorly (r = 0.36 and 0.57) in the middle group (between 2 and 3 and between 3 and 4) and correctly for values below 2 or over 4 micrograms/ml (r = 0.83 and 0.78 respectively).

CONCLUSION

These two optimum cutoff values (< 2 micrograms/ml and > 4 micrograms/ml) are useful for determining the need for further explorations for DVT. By limiting need for ultrasonography and contrast venography, the cost-efficacy ratio for the detection of DVT during the postoperative period is greatly improved with the D-Dimer screening strategy.

Pharmacology of respiratory control in neonates and children

The therapeutic approach of respiratory control disorders in neonates and young children is based on a clear understanding of the mechanisms involved in the regulation of ventilation according to the stages of postnatal development. A complete evaluation of drugs presenting either depressive or stimulative effects on ventilation is required.

Respiratory oscillation mechanics in infants with bronchiolitis during mechanical ventilation

The aim of the study was to describe the pattern of respiratory oscillation mechanics and responses to positive end-expiratory pressure (PEEP) in bronchiolitis. Six infants were studied during the course of mechanical ventilation. A 20 Hz sinusoidal pressure variation was applied at the endotracheal tube where flow was measured with a pneumotachograph. Resistance and reactance obtained from the complex pressure-flow ratio were separated during inspiration (R(rs,i); X(rs,i)) and expiration (R(rs,e); X(rs,e)), and the differences between R(rs,i) and R(rs,e) (deltaR(rs)) and X(rs,i) and X(rs,e) (deltaX(rs)) were calculated. The data were corrected for the mechanical characteristics of the endotracheal tube. The measurements were repeated while PEEP was varied between 0 and 8 hPa. Two infants were found to have normal R(rs) and near-zero X(rs) and both parameters exhibited little change within the respiratory cycle or with varying PEEP. Four infants had high R(rs) at zero PEEP. In two, R(rs,i) was markedly elevated (108.5 and 85.2 hPa.s/L, respectively), and X(rs,i) was markedly negative (-25.0 and -22.5 hPa.s/L, respectively) at zero PEEP, while deltaR(rs) and deltaX(rs) were small. R(rs,i) and the absolute value of X(rs,i) decreased with increasing PEEP. This pattern of oscillation mechanics was consistent with low lung volumes and atelectasis, being reversed by increasing PEEP. In the remaining two subjects, R(rs,i) was moderately elevated (57.8 and 53.6 hPa.s/L, respectively) and X(rs,i) moderately negative (-12.5 and -7.7 hPa.s/L, respectively) at zero PEEP. DeltaR(rs) (-59.8 and -56.5 hPa.s/L, respectively) and delta(rs) (28.1 and 48.7 hPa.s/L, respectively) were large, but were dramatically reduced by increasing PEEP. These patterns were consistent with expiratory airflow limitation. Measurements of respiratory impedance are, therefore, informative in regard to the pathophysiological mechanisms occurring in bronchiolitis during mechanical ventilation, and they may be helpful in setting the level and assessing the effect of PEEP.

Maturation of B cells in the lamina propria of human gut and bronchi in the first months of human life

Little is known of the maturation of the mucosae-associated lymphoid tissue (MALT) in man, because, for ethical reasons, tissues from newborns are not easy to obtain. We used the opportunity provided by autopsies systematically performed in infants who died of Sudden Infant Death Syndrome (SIDS) to study the maturation of the MALT after birth. Gut and bronchus samples of 90 infants from postpartum to 90 months and who died from SIDS were collected and studied by histological and immunofluorescence examination. Plasma cells, absent at birth, appeared within a few hours after birth and initially were of the IgM isotype. IgA plasma cells appeared at 12 days. These cells were first observed in gut and later in bronchi, indicating that maturation of the gut precedes that of bronchi. The number of plasma cells increased rapidly over time and IgA plasma cells became predominant after 3 weeks in the gut and 6 weeks in bronchi. At birth, only small IgM bearing B-cell foci were seen and organized germinal centers appeared to develop over a few days, first in the gut and only later in bronchi. These results confirm that, in man, the MALT organization at birth is still in its fetal form and that maturation depends on intestinal challenges and evolves over several weeks before IgA becomes the predominant isotype secreted.

Respiratory system reactance as an indicator of the intrathoracic airway response to methacholine in children

The upper airways may contribute to increases in airway resistance in response to a bronchial challenge, and thus decrease the specificity of such challenge tests to diagnose airway hyperresponsiveness when forced oscillation techniques are used to evaluate changes in respiratory system resistance (Rrs). A concomitent decrease in respiratory system reactance (Xrs) may indicate a change in the intrathoracic airways and/or lung parenchyma, provided that extrathoracic airway wall motion is prevented. To test the value of Xrs in the evaluation of bronchial hyperresponsiveness, we studied the respiratory impedance response to methacholine in 38 children with a history of asthma (aged 6-14.5 years), and compared the results to changes in the forced expiratory volume in one second (FEV1). Rrs and Xrs were measured by the forced oscillation technique with pseudorandom (11 subjects) or sinusoidal (27 subjects) pressure variations applied around the child's head to minimize upper airway wall motion. Changes in Rrs and in Xrs at 12 Hz (Rrs12, Xrs 12) correlated significantly with changes in FEV1 (P < 0.005). A decrease in FEV1 > or = 20% was observed in 23 subjects. When these 23 subjects were compared with the 15 children who did not show significant changes in FEV1, the responding group had larger mean +/- SEM changes in Rrs (116.0 +/- 13.2% vs 60.4 +/- 11.4%, P < 0.006) and in Xrs (-2.1 +/- 0.4 hPa.s/L vs -0.9 +/- 0.3 hPa.s/L, P < 0.03) than the nonresponders. The receiver operating characteristics (ROC) curve analysis was used to assess the diagnostic value, i.e., specificity and sensitivity, of different levels of change in Rrs and Xrs, with reference to FEV1. The overall incidence of false results was similar for Rrs and Xrs. The optimum diagnostic value for Rrs was a 70% increase, which corresponded to a sensitivity of 87% and a specificity of 67%. For Xrs the optimum decision level was -1 hPa.s/L, corresponding to a sensitivity of 70% and a specificity of 80%. It is concluded that Xrs may improve the specificity of the forced oscillation technique in interpreting the airway response to methacholine. This may be of particular interest in young children unable to perform forced expirations.

Specificity and sensitivity of respiratory impedance in assessing reversibility of airway obstruction in children

Flow in the upper airway wall induces significant error in estimating respiratory impedance by the standard forced oscillation technique in subjects with airway obstruction and may be minimized by oscillating pressure around the subject's head (head generator technique). The aim of this study was to determine whether the latter improves the power of forced oscillations in detecting airway response to bronchodilators in children. Seventy-five children with airway obstruction were studied (ages 5.5 to 15 years old). Fifty-three had asthma and 22, cystic fibrosis. A bronchodilator was administered, and the percent changes in respiratory resistance at 10 Hz (Rrs10), 20 Hz (Rrs20), respiratory compliance (Crs), and resonant frequency (fn) with standard and head generator were compared with the corresponding change in FEV1. The response was positive in 38 (delta % FEV1 > or = 15%) and negative in 37 patients. Data on Rrs10, Crs, and fn could not be obtained in 7, 8, and 4 subjects, respectively, for technical reasons. The delta % Rrs20 was not different between head and standard generator in nonresponders (mean +/- SEM: -19.0 +/- 4.5, vs -11.8 +/- 3.1%), but significantly larger with head than standard generator in responders (-54.1 +/- 3.0 vs -26.5 +/- 2.4%; p < 0.001). The optimal decision level determined by Receiver Operation Characteristic analysis showed that, compared with the standard method, the head generator improved the specificity of Rrs20 (78 vs 65%) with no change in sensitivity (76% for both). Resonant frequency had larger sensitivity with standard than with head generator (91 vs 53%) but slightly lower specificity (70 vs 78%). Finally, delta %Crs was more specific (72 vs 67%) and more sensitive (68 vs 52%) with standard than with head generator. The overall incidence of false results was lower with the head generator than with the standard generator for resistance and lower with the standard generator than with the head generator for fn and compliance. Thus, the head generator improves the diagnostic power of the forced oscillation resistance in establishing the reversibility of airway obstruction, but parameters derived from the reactance may have better diagnostic value with the standard method.

Gastroesophageal reflux and acute life-threatening episodes: role of a central respiratory depression

The aim of this study was to evaluate plasma levels of beta-endorphins in babies with gastroesophageal reflux (GOR) admitted for acute life-threatening episodes (ALTE). In case of ALTE (n = 15), beta-endorphin levels were significantly increased compared to sudden infant deaths syndrome siblings with GOR of a similar gravity evaluated for risk factors (n = 13). beta-Endorphin levels are decreased following successful treatment of GOR. Studies of ventilation suggest that changes in the central respiratory drive are associated with a reduction in plasma beta-endorphin levels.

Modification of ventilatory reflexes: an efficient therapy for apneas of prematurity?

The treatment of apneas of prematurity mainly involves the use of drugs (methylxanthines, doxapram). Despite evidence of the efficacy, some adverse effects may occur raising the question of other therapies. This brief review analyses the usefulness of methods influencing the ventilatory reflexes: cutaneous and proprioceptive stimulation and nasal continuous positive airways pressure proposed previously.

Effects of phenobarbital on cerebral blood flow during hypoxia

Phenobarbital (PB), at anticonvulsant dosages, has been used in an attempt to reduce hypoxic brain injury in asphyxiated newborn infants. The effects of PB pretreatment on the cerebral blood flow (CBF) response in hypoxia were studied in 15 curarized and mechanically ventilated piglets: 7 animals were pretreated with 20 mg/kg of PB (group 1) and 8 served as untreated controls (group 2). Successive aliquots (25 ml) of carbon monoxide were introduced into a closed ventilator circuit and CBF (measured with radiolabelled microspheres), arterial blood pressure, blood gases, arterial pH and PaO2 were subsequently determined at different levels of hypoxia. The amount of hemoglobin available for oxygen transport (i.e. total Hb-HbCO) was used to express hypoxic aggression and decreased from grade I (> 2 mmol/l) to grade II (1-2 mmol/l) to grade III (< 1 mmol/l). In the control group, CBF increased during grade-I hypoxia and continuously remained above baseline values during grade-II and grade-III hypoxia. In pretreated animals, however, only grade-II hypoxia was associated with a significant increase in CBF above baseline. In addition during grade-III hypoxia, CBF decreased to the prehypoxic values despite a fall in cerebral oxygen delivery and cardiac index. These data suggest that PB should be used with caution to prevent brain damage in the asphyxiated newborn infants.

[Hemodynamic and renal adaptation of newborn infants of hypertensive mothers treated with acebutolol]

A prospective study of the hemodynamic and renal changes was undertaken in 11 neonates whose mothers were treated with acebutolol for hypertension during pregnancy, compared with a control group of 11 infants born to normotensive mothers. Monitoring of the cardio-respiratory system was performed for a period of 4 days. Renal function was studied during 2 periods (12-36, 60-84 hours of life). Hemodynamic failure was observed in 5 of 11 children from treated mothers. The data concerning the renal function of treated group showed: 1) a diuresis significantly lower during the first period (p less than 0.05); 2) the absence of significant rise in the glomerular filtration rates during the second period; 3) a lower sodium balance during the 1st and 2nd periods (p less than 0.02 and p less than 0.05), a lower calcium balance during the 1st period (p less than 0.01). No relationship was found between the renal changes and the hemodynamic disturbances. The direct effect of the drug on the glomerular and tubular functions and/or the renal arteriolar vasomotricity could explain these changes in the renal function in the newborns prenatally exposed to acebutolol.

Doxapram for the initial treatment of idiopathic apnea of prematurity

The ventilatory effects of doxapram in the initial pharmacotherapy for apnea in the newborn were evaluated in 8 premature infants with idiopathic apnea. All received doxapram for 48 h at 0.25 mg/kg/h on the first day and 1 mg/kg/h on the second day. The ventilatory effects and the airway occlusion pressure (p0.1) were measured by means of a face mask, and a pneumotachograph. Compared to the pretreatment period, the mean of the frequency of central apnea greater than or equal to 15 s decreased significantly (p less than 0.01) by 48 and 75% during the first and second day, respectively. Both doses significantly increased inspiratory drive measured by airway occlusion pressure by 20% (p less than 0.05) and 32% (p less than 0.01) on the first and second day of drug treatment, respectively. Minute ventilation, tidal volume and mean respiratory flow significantly increased only with 1 mg/kg/h of doxapram, accompanied by a significant decrease in transcutaneous PCO2. No side effects were noted. Data suggested that doxapram alone at a dose of 1 mg/kg/h is effective for the treatment of neonatal apnea.

[Monitoring after total hip prosthesis. Value of semi-quantitative D-dimer assay]

Criteria for positive assay of the D-dimer were defined in order to establish its diagnostic value for phlebitis in the post-operative period. A retrospective study was carried out on the files of 94 patients who had received a total hip prosthesis in 1990. A semi-quantitative assay technique was used to measure the D-dimer because it is the only method giving immediate results. Three criteria were used to classify the results: criterium A: D-dimer greater than or equal to 2 micrograms/ml; criterium B: D-dimer greater than or equal to 4 times the preceding test; absence of both of these criteria. The results were compared to echo-doppler results and confirmed by phlebography when necessary. The incidence of proximal phlebitis was low (2 percent); criterium B showed a 100 percent negative predictability and a 29 percent positive predictability. None of the cases of phlebitis diagnosed with this test had been suspected clinically. This test provides a means of patient screening and spares the need for other explorations.

Hyperventilation restores autoregulation of cerebral blood flow in postictal piglets

Autoregulation of cerebral blood flow is impaired in the postictal state. This loss of autoregulation may in part be mediated by a rise in perivascular hydrogen ion and carbon dioxide concentration. We hypothesized that hypocarbia with a concomitant reduction in perivascular hydrogen ion and carbon dioxide concentration would restore autoregulation during the postictal state. We studied autoregulation of cerebral blood flow in 13 ventilated, awake 3- to 4-d-old piglets during the postictal state under normocarbic and hypocarbic conditions. During the postictal state, cerebral blood flow was pressure-passive in normocarbic piglets, whereas the relationship between cerebral blood flow and cerebral perfusion pressure was described by a polynomial curve in hypocarbic piglets. Because hypocarbia restores cerebral blood flow autoregulation in postictal newborn piglets, we speculate that the perivascular hydrogen ion and carbon dioxide concentration contribute significantly to the state of cerebral autoregulation in the postictal subject.

Respiratory mechanics in spontaneously breathing term and preterm neonates

The compliance (Crs), resistance (Rrs) and passive time constant (tau rs) of the respiratory system were determined by the single-breath method (sb) in 24 healthy term and preterm newborns. In 22 of them, Crssb was compared to the slope of the pressure-volume curve determined by the multiple occlusion technique (mo), which is not dependent on the assumption of a linear flow-volume relationship. Crssb and Rrs correlated significantly with body weight (kg): Crssb = 0.56 x kg + 1.22 (r = 0.67); Rrs = -20.1 x kg + 134.6 (r = -0.68). No difference in Crs and Rrs between prone and supine positions was found. tau rs was not significantly different between premature (0.21 +/- 0.06 s) and full-term infants (0.21 +/- 0.05 s). Crssb was significantly higher than Crsmo in premature babies (2.27 +/- 0.41 ml.cm H2O-1 vs. 1.98 +/- 0.47 ml.cm H2O-1. This difference may be explained by a continuous braking of expiratory airflow after release of the occlusion, or more likely, by a difference in the lung volume at which Crssb and Crsmo are measured. However, the difference between Crssb and Crsmo (approximately 15%) is in the same range as the intrasubject variability, and is meaningless compared to the alterations of respiratory mechanics observed during neonatal ventilatory disorders. Therefore, the single-breath method appears to be a suitable and noninvasive method to measure respiratory mechanics in nonintubated prematures.

Effect of sympathetic nervous system on cerebral blood flow in the newborn piglet

The role of the sympathetic nervous system on cerebral blood flow (CBF) autoregulation was evaluated in newborn piglets. Six animals were studied after ablation of the right superior sympathetic ganglion and compared to 6 control animals. Mean arterial blood pressure (MABP) was decreased by successive blood withdrawal and CBF was measured by radioactive microspheres. In denervated animals, MABP and CBF correlated positively according to a parabolic curve showing an absence of autoregulation when MABP is above 50 mm Hg (y = 0.079x2 - 5.9x + 154, p less than 0.01). In control animals, CBF remains stable throughout the experiment (y = 0.28x + 5). These data suggest a shift to the left of the upper limit of the autoregulation range in denervated animals and consequently a poor adaptation to increased MABP.

Persistence of impaired autoregulation of cerebral blood flow in the postictal period in piglets

Cerebral blood flow (CBF) autoregulation was evaluated in the postictal period in unanesthetized term newborn piglets with a mean age of 5.7 +/- 3 days. Seven animals (group 1) received 1 mg/kg bicuculline to induce brief generalized seizures, and six control animals (group II) received saline. Twenty to 90 min after the end of seizure activity in group I or saline injection in group II, CBF was measured by the radioactive labeled microspheres method at three levels of mean arterial blood pressure (MABP) obtained by controlled blood withdrawal within the normal range for autoregulation. In the postictal period, baseline CBF was higher in group I than in group II (85 +/- 21 vs. 48 +/- 7 ml/min/100 g, p less than 0.001). During hypotension, total CBF was positively correlated with variations of MABP in group I (r = 0.739, p less than 0.01) but not in group II. Regional CBF showed the same correlation with MABP. These data show that after seizures in piglets, the rise in CBF is associated with a persistent impairment of CBF autoregulation. These hemodynamic alterations may be relevant in the pathogenesis of hemorrhagic or ischemic brain lesions.

The management of bronchopulmonary dysplasia

After presentation of the actual knowledge concerning the pathophysiology of bronchopulmonary dysplasia, the prevention and the management of the disease are discussed. Techniques of ventilation, weaning procedures and prescription of drugs are also analyzed. The importance of a slow reduction of oxygen supply and the possibility of discharge with oxygen therapy is emphasized.

[Treatment of patent ductus arteriosus in premature infants by indomethacin]

Over a 4-year period, 63 premature babies presenting with patent ductus arteriosus were treated with indomethacin at two different dosage levels (0.1 and 0.2 mg/kg). For all infants the permanent closure rate was 68% (56% with 0.1 mg/kg and 75% with 0.2 mg/kg - n.s.) and the positive response rate (i.e. permanent and transient closure) 84%. There was no difference between the two dosages in the incidence of side-effects, particularly on diuresis, and in mortality and morbidity rates; the overall mortality rate was 31%. Pharmacokinetic studies performed in 51 cases did not show any difference related to indomethacin dosage. The changes observed after 2 or 3 doses resulted from improvement in haemodynamics. This study confirms the effectiveness of indomethacin in the treatment of patent ductus arteriosus and suggests an advantage for the 0.2 mg/kg dose.

Effect of seizures on brain phenobarbital concentration in newborn piglets

Phenobarbital (PB) brain and blood concentrations were measured together with brain and blood pH in newborn piglets before and at the end of seizure activity induced by pentylenetetrazol or bicuculline. Seizures induced a significant elevation of arterial blood pressure and profound changes in the blood gases and in the acid-base balance, with a marked reduction in brain tissue pH. Despite an intense brain acidosis, however, and a significant rise in blood/brain [H+] gradient, phenobarbital brain concentrations were not reduced during seizures but, on the contrary, were increased in 7 of 11 piglets. These data suggest that contrary to the pH partition hypothesis, brain uptake of PB is concomitantly increased during seizures and brain acidosis.

Treatment of persistent fetal circulation syndrome of the newborn. Comparison of different doses of tolazoline

The effects of two doses of tolazoline have been compared in 2 groups of newborns suffering from the persistent fetal circulation syndrome. The effects on PaO2 and AaDO2 were similar in the 2 groups who received either a bolus of 1 or 0.5 mg X kg-1 tolazoline, followed by a continuous infusion of 1 or 0.5 mg X kg-1 X h-1. The observed changes did not differ significantly from those previously observed in babies treated with 2 mg X kg-1. A rise in PaO2 and a reduction in AaDO2 were usually observed shortly after the bolus injection and at plasma levels between 1.5 and 4 micrograms X ml X -1. A progressive rise in plasma level over time occurred after 1 mg X kg-1 (and in the previous study of 2 mg) but not with 0.5 g/kg tolazoline. The elimination half-life of tolazoline in 6 patients was 5 to 13 h. The data suggest that continuous infusion of tolazoline is not necessarily required and that the dose of 0.5 mg/kg is more appropriate and safer than the higher doses usually proposed.

Effects of tolazoline on regional blood flows in the newborn piglet

To assess the effects of intravenous tolazoline on hemodynamics and regional blood flow distribution, 12 anesthetized newborn piglets were studied. Six piglets received saline and served as controls, the other 6 received two bolus doses of tolazoline (1 and 2 mg/kg). Mean arterial blood pressure decreased from control levels of 69.4 +/- 5.6 to 54.6 +/- 7.0 and 47.0 +/- 5.6 mm Hg, respectively, after 1 and 2 mg/kg of tolazoline, and heart rate increased from 220 +/- 9 to 270 +/- 13 and 282 +/- 8 beats/min, respectively. Cardiac output and regional blood flows were measured 15 min after tolazoline by the radioactive microsphere technique. Cardiac index did not change significantly. There was a redistribution of cardiac output toward the coronary circulation, with an increase in coronary blood flow from a control value of 249.3 +/- 39.9 to 361.0 +/- 56.4 ml/min/100 g of tissue after 1 mg/kg of tolazoline. Bronchial blood flow was also significantly increased. After a dose of 2 but not 1 mg/kg, the renal blood flow was markedly decreased from 139.8 +/- 17.8 to 104.4 +/- 24.5 ml/min/100 g. The other regional blood flows were not significantly modified. We conclude that tolazoline is a potent coronary vasodilator during the neonatal period. In addition we speculate that the decrease in renal blood flow might play a role in the renal toxicity of tolazoline.

Effect of diltiazem on hemodynamics and regional blood flows in the newborn piglet

The aim of our study was to evaluate the effects of the calcium antagonist diltiazem (DTZ) on hemodynamics and regional blood flows measured with radioactive microspheres during the neonatal period. For this purpose, two bolus doses (0.5 and 1 mg/kg) of intravenous DTZ were injected in six 2- to 6-day-old urethan-anesthetized piglets. Six other piglets were injected with saline and served as controls. DTZ arterial plasma concentrations measured by high-pressure liquid chromatography were 0.521 +/- 0.034 and 1.141 +/- 0.073 microgram/ml, respectively, after 0.5 and 1 mg/kg. The only significant hemodynamic effects of DTZ were a decrease in mean arterial blood pressure and in heart rate. The main effect of DTZ on regional blood flow was a striking increase in coronary blood flow (by 54%) after both 0.5 and 1 mg/kg. To a lesser extent, DTZ increased significantly the blood flow to the brain, liver, ileum, diaphragm, and lungs. In contrast, DTZ at a dose of 1 mg/kg induced a significant decrease in renal blood flow (by 37%). We conclude that DTZ in the neonatal period is a nonspecific vasodilator. However, the decrease in renal blood flow induced by a dose of 1 mg/kg might be detrimental and requires further investigation.

Regional cerebral blood flow during bicuculline-induced seizures in the newborn piglet: effect of phenobarbital

The changes in cerebral blood flow (CBF) during and after bicuculline-induced seizures were studied by the radioactive microsphere technique in 12 newborn, urethan-anesthetized piglets, 6 piglets pretreated with phenobarbital (10 mg/kg) and 6 without phenobarbital. The mean arterial blood pressure (MABP), PaO2, PaCO2 and the cerebral tissue pH (CtpH) were measured. CBF was increased during seizure, more in basal ganglia (98 and 106% in the control and phenobarbital group, respectively) than in brainstem, cerebellum and cortex. 15 min after seizure, CBF has returned to preseizure values. There was no significant difference at any time between the control and phenobarbital group. The increase in CBF was correlated with an increase in MABP (r = 0.753, p less than 0.01), suggesting a loss of cerebral autoregulation. CBF was significantly correlated with PaCO2 before and after seizure, but not during seizure. Finally, the increase in CBF was significantly correlated with an early increase in CtpH (r = 0.570, p less than 0.05), suggesting that brain acidosis is not involved in the pathogenesis of the increased CBF during seizures.