[Indications and application of exercise tests in children]. / Indications et réalisation pratique des épreuves d'exercice chez l'enfant.

Exercise tests are routinely used in children to assess cardio-respiratory and muscular adaptations to exercise. However these tests are of relatively recent use, and there is a lack of standardization and of relevant data in large groups in this population. The aim of this paper was to specify the common medical indications of exercise tests in children, to propose standardized protocols of these tests in some of the most common pathological situations as: exercise-induced asthma, chronic respiratory diseases (bronchopulmonary dysplasia, cystic fibrosis), muscular diseases. These tests can provide clinically relevant parameters only when they are used in strict conditions of standardization.

Usefulness of sniff nasal pressure in patients with neuromuscular or skeletal disorders.

Inspiratory muscle strength is an important variable in patients with neuromuscular or skeletal disorders. It is usually assessed by measuring maximal inspiratory pressure (PI(max)), but this test may prove difficult for some patients, and low values may originate from incomplete effort or air leaks. We assessed the usefulness of the novel sniff nasal pressure (Pn(sn)) test in 126 patients with a neuromuscular or a skeletal disorder, aged 5 to 49 yr. Pn(sn) was measured in an occluded nostril during maximal sniffs performed through the contralateral nostril. All patients performed the Pn(sn) maneuver easily, whereas 10 young and weak patients with neuromuscular disorders could not perform the PI(max) maneuver. Data were analyzed for the 116 patients who could perform both tests (92 patients with neuromuscular and 24 with skeletal disorders). When expressed as percents of the predicted values, Pn(sn) was similar to PI(max) in patients with neuromuscular disorders (54 +/- 25% predicted [mean +/- SD] versus 52 +/- 24% predicted), and was higher than PI(max) in patients with skeletal disorders (70 +/- 25% predicted versus 61 +/- 27% predicted, p < 0.05). Pn(sn) appeared to be the main determinant of VC in patients with neuromuscular disorders, whereas the Cobb angle and PI(max) were the main determinants of VC in patients with skeletal disorders. We conclude that inspiratory muscle strength can be easily assessed with Pn(sn) in children and adults with various neuromuscular and skeletal disorders. This new muscular parameter appears particularly useful in neuromuscular disorders, in which it represents a major determinant of VC.

Reduced lung diffusion capacity after Mycoplasma pneumoniae pneumonia.

BACKGROUND: Mycoplasma pneumoniae is a frequent but underdiagnosed cause of community-acquired pneumonia (CAP) in children, and appropriate macrolide treatment is often given late. The aim of this work was to estimate the frequency of pulmonary involvement in children 6 months after a clinical episode of Mycoplasma CAP. METHODS: We measured carbon monoxide diffusion capacity (TLCO) and conducted spirometric tests in 35 children without asthma or chronic lung disease (ages 4.5 to 15 years), 6 months and 1 year after acute CAP caused by M. pneumoniae (23 children), pneumococci (5 children) or viruses (7 children). Only 11 of 23 patients with M. pneumoniae CAP required hospitalization, whereas all the patients with pneumococcal or viral pneumonia were admitted to hospital. RESULTS: Lung volumes and spirometric tests were normal for all children. TLCO was normal 6 months after pneumococcal or viral pneumonia (87 to 112% of expected values for height and sex). After acute M. pneumoniae CAP, 11 of 23 patients (48%) had TLCO values <80% of the expected value. The extent of change in lung diffusion capacity was correlated with the delay to diagnosis and treatment: TLCO was low in 8 of 11 patients given macrolide treatment 10 days or more after the onset of acute symptoms vs. only 3 of 10 patients given appropriate treatment in the first 10 days. TLCO was low in 7 of 7 who received macrolide therapy for <2 weeks. TLCO had increased slightly after 1 year in the 5 patients retested after a new course of macrolide treatment. TLCO reached the lower normal range in 2 patients controlled after 3 years. CONCLUSIONS: The abnormal TLCO values suggest that some children with Mycoplasma pneumonia have reduced pulmonary gas diffusion after recovery from the illness. The reduction is related to delay and short macrolide therapy.

Non-endoscopic techniques for the evaluation of the pediatric airway.

In children with stridor, a detailed evaluation of the airway is often required to assess precisely its anatomical and functional status. Various methods of assessment have been developed and airway management may include, as well as rigid and flexible endoscopy, the use of imaging techniques such as plain X-rays, a barium oesophagogram, ultrasound, a CT scan, a magnetic resonance image (MRI) and an angiogram, as well as respiratory function tests including acoustic rhinometry and flow volume loops or even pH monitoring. This article aims to highlight the valuable information these alternative techniques can provide.

[Exercise intolerance caused by muscular phosphorylase kinase deficiency. Contribution of in vivo metabolic studies]. / Intolérance à l'effort par déficit en phosphorylase kinase musculaire. Apport des investigations métaboliques in vivo.

A 33 year old man has been presenting since childhood an exertional muscle pain syndrome without myoglobinuria. Muscle biopsy revealed a vacuolar myopathy with glycogen excess in subsarcolemmal and intermyofibrillar spaces which was confirmed by electron microscopy. Plasma production of ammonia was abnormally high during exercise on a bicycle ergometer while the raise of lactate was normal. NMR spectroscopy showed an increased muscle glycogen content, with a slight and delayed drop of the pH during exercise. Phosphorylase b kinase activity was undetectable in muscle specimen whereas activities of others enzymes of carbohydrate metabolism were normal. Clinical presentation of our patient is compared to that of the reported cases of phosphorylase b kinase deficiency.

[Community-acquired pneumonia in children: importance of Mycoplasma pneumoniae infections and efficacy of antibiotics]. / Pneumonies communautaires de l'enfant: importance des infections à Mycoplasma pneumoniae et efficacité des antibiotiques.

OBJECTIVES: Define a therapeutic management schema adapted to children with community-acquired pneumonia. METHODS: A prospective survey was conducted in 104 children over 18 months of age with community-acquired pneumonia. The pathogen was isolated in 85% of the cases. RESULTS: Viral infection alone was proven in 30 children (respiratory syncytial virus in 10). Pneumococci pneumonia was found in 12 patients; the isolated strains were sensitive to penicillin. Apyrexia was obtained in 11/12 cases with amoxicillin. Mycoplasma infections occurred in 42% of the cases (41 alone and in association with pneumococci in 2 cases). Pneumococci and mycoplasma infections could not be differentiated with standard radiography and laboratory tests. Initial treatment with beta lactamines was always unsuccessful in children with mycoplasma infections. Apyrexia was achieved when antibiotics were changed to macrolides. CONCLUSION: Since lower respiratory tract infections due to pneumococci are much more severe than those due to mycoplasma, beta lactamines should be given as first intention treatment for children over 18 months with pneumonia. Macrolides should be given in case of failure because mycoplasma would then be the most probable infectious agent.

Alteration of lung diffusion capacity in IgA nephropathy.

OBJECTIVE: To establish whether changes of lung transfer for carbon monoxide (TLCO) are related to the phase of IgA nephropathy. METHODS: Respiratory function was tested in 12 children with IgA nephropathy assessed by percutaneous renal biopsy. This was done during acute exacerbations or haematuria-free phases of the disease. RESULTS: TLCO was low in 12/13 measurements made in the haematuric phase of IgA nephropathy or during the month following gross haematuria (mean TLCO 64% of expected values). Lung volumes and blood gas values were normal and only minor radiological signs of interstial lung involvement were observed in 11/12 patients. When respiratory tests were performed more than three months after gross haematuria, TLCO was low in 4/9 patients, with no relation to the significance of residual proteinuria or severity of findings at renal biopsy. There was a significant difference between tests performed when haematuria was present or recent and those performed more than three months after an episode of gross haematuria (p < 0.01). CONCLUSIONS: The decrease of TLCO in the acute phases of the disease is probably related to alterations of the lung alveolarcapillary membrane by immune complexes containing IgA. This non-invasive technique, easy to perform and repeat, could be of value in the diagnosis of IgA nephropathy in haematuric children.

Small-bowel bacterial overgrowth in children with chronic diarrhea, abdominal pain, or both.

OBJECTIVE: To evaluate the frequency of small-bowel bacterial overgrowth (SBBO) as a cause of chronic digestive symptoms in a large cohort of children, using the glucose breath hydrogen test (BHT). DESIGN: Patients were 53 children (aged 2 months to 12 years) with chronic diarrhea, abdominal pain, or both. Diagnosis of SBBO was defined with a BHT by a change in H2 concentration of 10 ppm H2 or more in expired air after an oral glucose load. Patients with a positive BHT result were included in group 1 and treated with a combination of colistin and metronidazole for 10 days; a second BHT was performed 1 month later. Group 2 comprised patients with a negative BHT result. Group 3 (n = 15) was a control group of healthy subjects, and group 4 (n = 6) a comparison group of subjects with bacteriologically documented SBBO. RESULTS: Eighteen patients (34%) had a positive BHT result and 35 a negative result. The BHT results were comparable in groups 1 and 4 and in groups 2 and 3, respectively. Fasting H2 levels were higher in group 1 than in groups 2 (p < 0.001) and 3 (p < 0.01). In group 1, children were younger than in group 2 (1 +/- 1 year vs 3.9 +/- 3 years; p < 0.001) and diarrhea was frequent (83%), but 17% of patients had abdominal pain alone. Fetid stools (p < 0.01), mucus in stools (p < 0.01), and flatulence (p < 0.05) were more frequent in group 1 than in group 2. Antibiotic treatment of children in group 1 led to a rapid disappearance of symptoms and normalization of BHT results. CONCLUSION: SBBO appears to be a frequent cause of chronic digestive symptoms in children, especially before the age of 2 years. The BHT provides a simple and noninvasive method of detecting it. The recognition of SBBO in children leads to effective treatment.

[Measurement of peak expiratory flow in young children: comparison of four portable equipments]. / Mesure du débit expiratoire de pointe chez les jeunes enfants: comparaison de quatre appareils portables.

BACKGROUND: Peak expiratory flow (PEF) monitoring is seldom used in young children because peak flow meter normal values are needed for children less than 7 years old. POPULATION AND METHODS: PEF was measured in 152 non asthmatic school children, aged 2.9 to 14.5 years with four peak flow meters (Assess, DHS, Vitalograph, MiniWright). Calibration of these peak flow meters were performed with flows ranging from 100 to 700 l/min with a calibration syringe. RESULTS: Calibration demonstrated the excellent linearity of each device but there was a slight overestimation by DHS and MiniWright, and a slight underestimation by Vitalograph and Assess. PEF measured with the four devices was better linearly correlated with height (r = 0.72 to 0.77) than with age. Differences similar to calibration have been found between the four linear regressions. CONCLUSION: These results indicate that PEF can be used in young children less than 7 years old. It is necessary to always use the same peak flow meter for a child.

[Abdominal pain in children caused by lactose intolerance. Prospective use of the hydrogen breath test]. / Douleurs abdominales de l'enfant par intolérance au lactose. Utilisation prospective du test respiratoire à l'hydrogène.

OBJECTIVES: We performed the breath hydrogen test in children consulting for abdominal pain in order to determine the minimal quantity of lactose required to prove malabsorption with least patient incomfort and to evaluate the effect of an adapted diet in children with a positive test. METHODS: The breath hydrogen test after lactose intake was performed in 109 children (51 boys, 58 girls, mean age 8.2 + 3.2 years, range 3 to 15) seen for unexplained abdominal pain. All these children had complained of abdominal pain daily for at least 6 months and no other cause could be identified. Children with acute or chronic diarrhoea or constipation were excluded. Nineteen children had been transferred from the surgery unit and 6 had been followed by the psychiatry unit. All these children drank milk regularly. RESULTS: The diagnosis of lactose intolerance was established in 83 children (76.1%) on the basis of a hydrogen peak in the breath after lactose ingestion. One-fourth of the children were of French origin and the others had at least one grandparent who was of Mediterranean or African origin. A lactose-free diet was proposed and led to the disappearance of abdominal pain in 24% and a clear improvement in 32%. CONCLUSION: The breath hydrogen test is a simple non-invasive test which allows a selection of children who could benefit from a lactose-free diet although it cannot be used to predict the effect of diet.

E1 pyruvate dehydrogenase deficiency in a child with motor neuropathy.

We report the case of a boy who developed a motor neuropathy during infectious episodes at 18 mo and 3 y of age. When he was 7 y old, he suffered persistent weakness and areflexia; his resting lactate and pyruvate values were 3.65 mM and 398 microM, respectively (controls: 1.1 +/- 0.3 mM and 90 +/- 22 microM), and an exercise test demonstrated a lactic acidosis (13.6 mM; controls: 6.4 +/- 1.3 mM) with a high pyruvate level (537 microM; controls: 176 +/- 15 microM) and a low lactate/pyruvate ratio (24.2; controls: 35 +/- 2). The results of polarographic studies on muscle mitochondria suggested a defect in pyruvate oxidation (pyruvate 17 ng atom O/min/mg protein; controls: 115 +/- 42), whereas glutamate, palmitoylcarnitine, and succinate were good respiratory substrates. The activity of total pyruvate dehydrogenase complex (PDHC) in muscle mitochondria and in fresh mononuclear cells was markedly decreased (9.7 and 0.054 nmol 14CO2/min/mg protein, respectively; controls: 123 +/- 4.5 and 0.733 +/- 0.03, respectively). Immunochemical analysis in muscle mitochondria demonstrated an absence of the alpha and beta E1 PDHC subunits. After 2 y of treatment with 500 mg/d thiamine, the patient was clinically improved. A genetic study of the main regions of mutations (exon 10 and 11) in the X chromosome encoding for the E1 alpha subunit of PDHC did not show any mutation. These data indicate that, although genetically different, this case enters in a very rare category of patients with PDHC deficiency without cerebral dysfunction and improved by thiamine + L-carnitine therapy.

Exercise intolerance in patients with McArdle's disease or mitochondrial myopathies.

OBJECTIVES: To assess respiratory and metabolic adaptations in patients with phosphorylase deficiency and mitochondrial myopathies using maximal exercise tests. PATIENTS AND METHODS: Five patients with McArdle's disease and five patients with mitochondrial myopathies performed the same incremental maximal exercise test. Their respiratory gas exchanges and the variation of the venous blood metabolites--lactate (LACT), pyruvate (PYR), alanine (ALA), ammonia (NH3)--were studied in comparison with the results of fourteen control subjects who performed the same test. RESULTS: Compared with controls, the two groups of patients displayed a similar significant decrease of their maximal VO2. In McArdle's patients the limitation of the maximal oxygen consumption was associated with a low respiratory exchange ratio (RER), a high VE/VO2, and characteristic metabolic data: no rise of LACT and PYR, a decrease of ALA and an important rise of NH3. In mitochondrial myopathies low VO2 max were due to a leftwards shift, i.e. towards low powers of exercise, of LACT, PYR, NH3 and ALA values. However the pattern of increase of LACT, PYR and NH3, exponential, and of ALA, linear, as well as respiratory exchange ratios were similar to control values. In this case, the limitation of oxygen consumption was due to a lack of the usual substrate, pyruvate. Low respiratory exchange ratio demonstrated that the muscle metabolism had a tendency to shift to lipid oxidation. CONCLUSION: These results suggest that patients with McArdle's disease may improve their muscle energy production by endurance training which enhances lipid metabolism, whereas in mitochondrial myopathies, the energy production by oxidation of pyruvate or lipids may be improved only by enzymatic substitution.

Impairment of lung diffusion capacity in Schönlein-Henoch purpura.

Twenty-nine children with typical Schönlein-Henoch purpura (SHP) were tested at the initial phase of the disease for respiratory function. Of the 29 patients, 28 had a decrease of lung transfer for carbon monoxide (TLCO) as measured by a steady-state method. Lung volumes and blood gas values were normal; slight radiologic signs of interstitial lung involvement were observed in 18 of 26 patients. There was a decrease in TLCO to 56.8% of normal values for height and gender and to 58.5% when normal values were volume-adjusted to functional residual capacity. In 19 of 25 patients, TLCO measurements were performed at 3-month intervals during follow-up. In all cases, normalization of TLCO values was observed only after complete clinical recovery from SHP. All children with persisting symptoms, even limited to microscopic hematuria or slight proteinuria, had low TLCO values. In one patient low TLCO during follow-up preceded a late relapse of SHP in the form of acute nephritic disease with characteristic IgA deposits on renal biopsy. We conclude that low TLCO in SHP is probably related to alteration of the alveolar-capillary membrane by circulating immune complexes. This noninvasive technique may be useful in diagnosis, and during the follow-up of the disease as an early indicator of reactivation.

Influence of intestinal parasitism on lactose absorption in well-nourished African children.

Hydrogen breath tests were performed in Gabon (Central Africa) after a loading dose of lactose in 67 well-nourished African children (50 with intestinal parasites and 17 unparasitized) and in 18 unparasitized young adults. All had normal nutritional status, and none had diarrhea or digestive symptoms. Parasites that were found included Ascaris lumbricoides in 76% of the parasitized children, Trichuris trichiura in 58%, Giardia in 24%, Entamoeba histolytica in 20%, Schistosoma intercalatum in 16%, and Necator Americanus in 14%. A similar proportion of parasitized (64%) or unparasitized (62.8%) subjects were lactose malabsorbers. Giardia infection was associated with a higher, but not significantly different, proportion of lactose intolerance (10 of 12, 83.3%). The presence of infection with A. lumbricoides or T. trichiura did not increase the percentage of lactose malabsorption. These data indicate that a decrease of lactase activity in well-nourished African children is not related to the presence or the importance of Ascaris or other intestinal parasites if the nutritional status is normal.

Physical exercise and voluntary hyperventilation in childhood absence epilepsy.

The aim of this study was to compare the effects of a physical exercise test and of voluntary hyperventilation between controls and children with absence epilepsy. Eighteen children (6 controls and 12 epileptics) were studied during rest (R), a maximal physical exercise test (15 min; PE), recovery (REC) and voluntary hyperventilation (3 min; VHPV). EEG and ECG were recorded during the experiment; respiratory parameters were measured to quantify PE; plasma levels of pH, lactate, pyruvate, glucose and antiepileptic drugs were determined. A decrease in the number of absences was observed during PE whereas an increase was observed during VHPV. We found significant positive correlations between the number of children with absences, the total number of absences for each state, frequency of absences per minute and the corresponding mean plasma pH, which demonstrate that the lower the pH is, the fewer absences occur. On the other hand, there was no relationship between the number of absences and the values of other parameters. Relations between variations of the plasma value of the pH, and thus the probable cerebral value of pH, and neuronal excitability are discussed. Our results indicate that children who suffer absence epilepsy should not be discouraged from sport practice.

[Maternal depression as a severity factor in respiratory hypersensitivity in children]. / La dépression maternelle facteur de gravité dans l'allergie respiratoire de l'enfant.

Of 136 children under 13 yr of age with allergic respiratory disease, 91 had an obstructive syndrome, at rest or induced in the laboratory, without relationship to the clinical symptoms described by the families. In the at-rest group, mothers have been more frequently subjected to depression during the child's infancy. This history of maternal depression appears to increase the frequency of the obstructive syndrome at rest in the child, with a relative risk of 2.87.