[Methacholine challenge in young children: measurement of resistance by interruption]

The aims of this study were 1. To evaluate the measurement of resistance by interruption (Rint) of bronchoconstriction induced by inhalation of methacholine and 2. To determine a threshold of increase of resistance in young children to differentiate responders from non-responders. Forty-six children (mean age 5 [4.3-6.1] years) referred for methacholine challenge were tested by measurement of Rint and transcutaneous oxygen tension. A fall of 20% or more in oxygen tension from the baseline was used to define the responders. The children studied had a baseline Rint significantly higher than normal (0.84 [0.68-1.01] vs. 0.76 [0.60-0.90] kPa L(-1)s; p < 0.03). Forty-one children were responders and had an increase in Rint significantly different from the non-responders (p < 0/04). An increase in Rint of 35% distinguished responders from non-responders in young children with chronic cough. Interrupter resistance increases significantly during bronchial provocation in responding young children and may be used to measure the degree of bronchoconstriction.

[Diseases of the pulmonary lymphatic system in children]

Diseases of the lymphatic system in children include a group of exceptional conditions difficult to manage. The anatomy of lymphatic system is complex in the lung. Variable from one subject to another, its complex physiology plays an important role in air-blood exchanges occurring in the lung. In the pulmonary interstitium and in the pleura, the lymphatic system acts like an overflow valve capable of regulating variations in interstitial fluid. The presence or development of dysplasic lymphatics causes leakage, dilatation, and reflux of the lymph through incontinent valves leading to chylothorax and/or fluid overload in the pulmonary interstitium. Symptomatic care is usually proposed, based on a fat-free diet supplemented with light-chain triglycerides and liposoluble vitamins. Other therapeutic options can be proposed. Medical options include cytotoxic agents, somatostatin, and interferon-alpha. Surgery may also be useful, but an assessment of therapeutic efficacy is very difficult due to partial effects and the small number of cases studied.

Genotype analysis and phenotypic manifestations of children with intermediate sweat chloride test results

STUDY OBJECTIVES

Cystic fibrosis (CF) is one of the most common inherited diseases among whites. Since the cloning of the CF transmembrane conductance regulator (CFTR) gene, a number of studies have focused on associations between the genotype and phenotype in CF. This had led to the progressive identification of new groups of patients, including those who have mild lung disease and those who have normal sweat chloride values (< 60 mEq/L). The aim of the present work was to provide information on the genotype and the phenotypic characteristics of children with intermediate-range sweat chloride test results.

PATIENTS AND RESULTS

We focused on children referred to the pulmonary department for various types of pulmonary disease and who had several sweat chloride test results with median values in the range of 40 to 60 mEq/L. Twenty-four patients over a 10-year period were enrolled (mean age, 4.8 years). Respiratory manifestations at initial evaluation included recurrent bronchitis, wheezing, chronic cough, and pneumonia. The duration of the follow-up ranged from 0.5 to 10.5 years. Sputum cultures revealed the presence of Haemophilus influenzae (10 children), Staphylococcus aureus (4 children), and Pseudomonas aeruginosa (3 children). Pancreatic insufficiency was found in two patients. Analysis of the entire coding sequence allowed identification of 16 known mutations in CFTR gene. Fifteen chromosomes (31.2%) carried a mutation in CFTR gene and one allele carried two mutations. Three patients were homozygous or double heterozygous (DeltaF508/DeltaF508, DeltaF508/3849 + 10 kb C-->T, S1235R/G551D). The 5-thymidine allele was identified in four children.

CONCLUSION

These results indicate an higher frequency of CFTR gene mutations in patients with borderline sweat chloride test results, compared to data reported in the general population. They lead to the recommendations for complete pulmonary and GI investigations in this group of patients, as well as assiduous care and medical follow-up.

Distinct sputum cytokine profiles in cystic fibrosis and other chronic inflammatory airway disease

The dominant role of inflammation in airways disease progression in cystic fibrosis (CF) is now well established and, based on recent findings, the possibility of an inappropriate inflammatory response in the lung of patients with CF has emerged. In order to characterize this response, the aim of the present work was to evaluate the levels of a number of pro- and anti-inflammatory cytokines in the sputum of CF children and to compare these levels to those observed in the sputum from non-CF children with diffuse bronchiectasis (DB). Three groups of patients were investigated: a group of 25 CF children (mean age: 12.2 yrs), a group of 10 non-CF children with DB (mean age 11.5 yrs), and a group of five healthy young adults (mean age 24 yrs). Elevated concentrations of pro-inflammatory cytokines, tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta and IL-8 were found in children with CF and in non-CF children with DB, with significantly higher concentrations of IL-1beta in CF children. Analysis of the natural anti-inflammatory cytokine IL-1 receptor antagonist (IL-1ra) and type II TNF soluble receptor (sTNFRII) concentrations showed distinct patterns, with elevated levels of both inhibitors in CF patients, whereas only sTNFRII was found to be increased in non-CF children with DB. IL-10 data indicated low concentrations in the CF group. In all CF children, the concentrations of IL-6 in the airways were extremely low, independent of the clinical, bacteriological or functional status. By contrast, significantly increased IL-6 levels were found in non-CF children with DB. These results document distinct cytokine profiles in cystic fibrosis patients and noncystic fibrosis patients. They also suggest that impairment of interleukin-6 expression may represent an important component of the excessive inflammatory response observed in cystic fibrosis.

Chronic interstitial lung disease in children: response to high-dose intravenous methylprednisolone pulses

The prognosis for children with chronic interstitial lung disease is poor and the mortality rate is high, especially in infants. This explains the many therapeutical protocols which have been proposed and investigated by several authors. In the present work, we evaluated the response of three infants with idiopathic pulmonary fibrosis to high-dose intravenous prednisolone pulses. The patients were referred to the department at the age of 4, 17, and 3 months, respectively. The diagnosis was confirmed by open lung biopsy and intravenous pulse methyl prednisolone therapy was started with the following protocol: 300 mg/m2 methylprednisolone daily for 3 days, repeated every 4 to 6 weeks. Because of the extreme severity of the respiratory distress at the time of diagnosis, the intravenous pulse treatments were initially complemented by oral prednisone. Clinical improvement was noticed within 6 months with progressive correction of hypoxemia. After follow-up for 3.5 to 4 years, with a total number of pulses of 37, 26, and 32, respectively, the children are symptom-free and do not require oxygen supplementation. During this period, no side effects and no adrenal insufficiency could be documented. Based on current knowledge of steroid action, it can be speculated that the response to intermittent high-dose intravenous methylprednisolone may explain the ability of this mode of hormone administration to maintain an adequate level of glucocorticoid receptor expression. More information and trials through multicenter collaborations are needed to assess therapeutical protocols of repeated high-dose intravenous steroid treatment.

Expression of insulin-like growth factors and their binding proteins by bronchoalveolar cells from children with and without interstitial lung disease

The involvement of the insulin-like growth factor (IGF) system in lung growth and repair following injury is sustained by a number of studies. Based on this knowledge, the aim of the present work was to document the expression of the IGFs and their binding proteins by alveolar cells obtained by bronchoalveolar lavage (BAL). Two groups were investigated: a control group of five children and a group of 11 children referred to the department for exploration of interstitial lung disease (ILD). Components of the IGF system studied included IGF-I, IGF-II and IGF-binding proteins (IGFBP). Expression of these factors was analysed at the level of messenger ribonucleic acid (mRNA) (by semi-quantitative reverse transcription polymerase chain reaction techniques), and of protein for the IGFBPs. In addition, expression of two major cytokines associated with the inflammatory process, tumour necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta (TGF-beta), was also documented. In children without parenchymal disease, the growth factor expressed was IGF-I, in association with the presence of mRNA for IGFBP-2 in all cases. In children with ILD, expression of IGF-I was observed in nine patients and of IGF-II in three patients, and the presence of IGFBP-2 was found in all extracts analysed (mRNA and proteins). Evaluation of IGFBP-2 expression indicated an increase in the group of children with ILD. Interestingly, a significant association was observed between the increase in IGFBP-2 expression and TGF-beta expression. The present data emphasize the presence on insulin-like growth factor-binding protein-2 in the BAL of all patients, and suggest that this protein may be an important factor of the injury/repair processes during the progression of alveolar inflammation.

Effects of hypercapnia and hypoxia on inspiratory and expiratory diaphragmatic activity in conscious cats

The influence of steady-state changes in chemical stimuli on ventilation and electromyographic activity of the diaphragm during both inspiration (total DI) and expiration (total DE) was studied in unanesthetized intact adult cats before and after carotid denervation. In intact animals, during hypercapnia (2 4, and 6% CO2), tidal volume (VT) and total DI increase, whereas total DE did not consistently change. During ambient hypocapnic hypoxia (14, 12, and 10% O2), VT increased only at 10% O2, whereas total DI increased at all levels studied. Total DE increased substantially at 14% O2, persisting up to the end of expiration with 12 and 10% O2. This effect was markedly attenuated during normocapnic hypoxia. During CO hypoxemia (1,700 ppm in air), VT as well as total DI and total DE decreased because of a large reduction in inspiratory and expiratory time elicited by tachypneic breathing. The effects of hypercapnia and hypoxia persisted after carotid denervation. Therefore, 1) in contrast to hypercapnia, hypoxia markedly enhances the expiratory diaphragmatic activity, 1) this expiratory braking mechanism depends on the severity of hypoxia and is partly due to hypocapnia secondary to hypoxia; and 3) because this effect was observed after carotid denervation and during CO hypoxemia, it may arise in the central nervous system, possibly in bulbopontine structures.

Ventilatory strategy in hypoxic or hypercapnic newborns

In conscious newborns, the ventilatory response to hypoxia is characterized by precocious hyperventilation followed by tardive hypoventilation, the latter disappearing with age. The hypoventilation could be mainly related to a weak peripheral drive and to the persistence of the diaphragmatic activity during expiration. Also, a decrease in metabolic rate and body temperature interferes with the response. The hyperventilation in response to hypercapnia increases as maturation proceeds and the maturation of the peripheral chemoreceptors contribute to this effect, as during hypoxia. The responses to both stimuli depend on many factors such as sleep state, anesthesia or ambient temperature.

Pulmonary sarcoidosis in children: serial evaluation of bronchoalveolar lavage cells during corticosteroid treatment

The clinical course of sarcoidosis in children has not been well defined. Eight children with symptomatic sarcoidosis included in this study underwent pulmonary function tests and bronchoscopy with bronchoalveolar lavage (BAL) before treatment and during steroid therapy. At the start of therapy, functional parameters, mostly dynamic lung compliance and lung transfer factor for CO, were impaired. This was associated with abnormalities of BAL cell populations: increased total cell number with a high proportion of lymphocytes, modifications of lymphocyte subpopulation with an elevated CD4+/CD8+ ratio, and enhanced ability of alveolar macrophages to release hydrogen peroxide. Although respiratory abnormalities seemed to be similar at the initial stage of sarcoidosis in children and adults, the course of the disease appeared to be different. Despite the absence of respiratory symptoms and disappearance of chest radiographic abnormalities on prolonged steroid treatment, we found slow improvement of pulmonary functions associated with persistence of BAL lymphocytosis and elevated CD4+/CD8+ ratios. However, the ability of alveolar macrophages to release hydrogen peroxide was significantly reduced after 6 months of steroid treatment, and it remained identical to the control group. Therefore, the evaluation of disease activity appears to be critical for therapy in pediatrics, and for this purpose studies of alveolar macrophage activation may be of particular interest.

[Respiratory form mof myasthenia gravis]

BACKGROUND

Extraocular, facial, bulbar and intercostal muscles are frequently affected in juvenile myasthenia gravis, especially during exacerbations. Acetylcholine receptor antibodies are often present in the blood in this type of myasthenic syndrome.

CASE REPORT

A girl presented with an exertional dyspnea at the age of 13 years, that improved after rest. All investigations were negative, except for lung function tests that showed a restrictive pattern. The diagnosis of juvenile myasthenia gravis was finally made at the age of 15 years because of the recurrence of sudden exertional dyspnea and a history of subtle weakness on repetitive movement leading to poor suckling, together with vocal and occasional swallowing difficulties. Dyspnea immediately improved after intravenous injection of 1 mg neostigmine, but the response was transient. No acetylcholine receptor antibody was found and a search for thymoma proved negative. Ambenonium chloride (Mytelase) was effective on clinical exacerbations, but the only improved test after 9 months of treatment was the functional residual capacity.

CONCLUSION

Anticholinesterase drugs must be tried in patients who present exertional dyspnea without bronchopulmonary or cardiac disease on the presumption of myasthenia gravis even when ocular or bulbar manifestations are absent.

[Asthma in infants. Clinical and functional aspects]

BACKGROUND

The incidence of asthma in infancy is rising but its clinical and physiological components remain unclear.

METHODS

A total of 24 infants, aged less than 48 months, in whom the first wheezing episode (WE) appeared before the age of 30 months (mean age: 9 months) underwent clinical examination and pulmonary function tests at least 2 weeks after the last WE.

RESULTS

The mean WE frequency was 1.1 per month and the mean number of admissions for WE was 1.8. 63% of patients showed symptoms between WE and 50% had an allergic profile. There was no evidence of thoracic distension. Bronchial obstruction (BO) occurred in 71% of patients; among these, BO was distal or generalized in 59% and medium or severe in 47%. 12.5% of patients were hypoxemic at testing. BO was less severe in patients treated with theophylline; it was more frequent (87%) in those with symptoms between WE and/or several admissions, and/or admission to the intensive care unit.

CONCLUSION

This study provides additional evidence that infants presenting with asthma at an early age have severe clinical and physiological profiles.

Diaphragmatic and ventilatory responses to alveolar hypoxia and hypercapnia in conscious kittens

Ventilation and electromyographic (EMG) activity of the diaphragm were recorded in unanesthetized kittens 2 and 10 wk of age during normoxia, hypercapnia (2 and 4% CO2), and hypoxia (12 and 10% O2). We measured integrated diaphragmatic EMG activity at end inspiration (DIAI) and end expiration (DIAE); the difference (DIAI-E), which represents the phasic change of the diaphragmatic activity, was considered responsible for a given tidal volume (VT). During hypercapnia, the 2-wk-old kittens increased minute ventilation (V) by increases in both VT and respiratory frequency (f), whereas the 10-wk-old kittens increased V primarily by an increase in VT. At both ages, DIAI and DIAI-E increased during hypercapnia, whereas DIAE did not change significantly. During hypoxia, in the young kittens, V and VT decreased while f increased markedly; in the older kittens, V, VT, and f did not change significantly. In kittens of both ages, DIAI increased during hypoxia; because diaphragmatic activity persisted into expiration, DIAE also increased. DIAI-E, as well as VT, was decreased in the young kittens, whereas in the older ones DIAI-E was slightly increased despite an unchanged VT. Finally, the ventilatory and diaphragmatic response to hypoxia changes with maturation in contrast to the response to hypercapnia. It is concluded that 1) the hypoxia-induced reduction of VT may result from prolongation of diaphragmatic activity into expiration, inasmuch as it induces a reduction of the phasic change of the diaphragmatic activity, and 2) because DIAI-E indirectly reflects central inspiratory output, a central mechanism should be involved in the reduced VT and V in response to hypoxia in newborns.

[Mediastino-pulmonary sarcoidosis in children. Clinical study, analysis of data of bronchoalveolar fluid lavage and respiratory function tests, therapeutic trends]

A series of 27 children (mean age: 12 yrs, 5 mos.) presenting with thoracic sarcoidosis is reported. This series, collected from 1961 to 1988 shows the rarity of the disease at that age. However the low rate of asymptomatic forms (22%) suggests that the frequency of the disease is underestimated, as it is not diagnosed. The histological proof is necessary for the diagnosis. When peripheral lesions available for biopsy are lacking, a liver needle biopsy is helpful (93% of positivity). This study shows the frequency of multivisceral types, the intensity of the macrophagic and lymphocytic alveolitis. The therapeutic indications depend on the comparison of the radiological stage, the results of pulmonary function tests (PFT), those of the bronchoalveolar lavages (BAL) and of the serum granulomatous activity markers, especially concerning angiotensin converting enzyme (ACE). When present at the beginning of evolution, several risk factors lead to use a corticosteroid treatment: age of onset before 4 years, multivisceral involvement, presence of functional pulmonary signs, delayed diagnosis and onset of treatment, impaired respiratory function (especially concerning the alveolo-capillary diffusion), PMN cells greater than or equal to 2% in the initial BAL, and IgG proteins greater than 4 SD. Thus sarcoidosis in children differs from that seen in adults as it has a more marked evolutive tendency and leaves severe sequelae in one third of patients.

[Cystic fibrosis in infants revealed by severe respiratory distress. Mid-term course]

We report the follow-up of 13 infants aged 2.5 to 24 months in whom cystic fibrosis disease presented as respiratory distress. All infants received an intensive treatment. Mean clinical, radiological and microbiological follow-up was 3.1 years. Ten children aged 1.5 to 8.5 years are still alive. One of them presents with serious respiratory failure, with a Shwachman score of 50. The Shwachman score is between 85 and 70 for 8 of 13 and 65 for one. The prognosis of this group did not differ from the one usually observed in the disease. It depends partially on early intensive care management and is not altered by mechanical ventilation.

Breathing pattern during exercise in untrained children

Breathing pattern during exercise on a cycle ergometer was studied in 18 untrained children aged from 6 to 15 years of age (9 boys, 9 girls). Oxygen uptake, tidal volume, minute ventilation, all normalized for body weight (VO2BW, VT BW, VE BW), respiratory frequency (f), inspiratory (TI) and expiratory (TE) times, ratio TI over total duration of the respiratory cycle (TI/TTOT) and mean inspiratory flow (VT BW/TI) were measured: (1) at rest (W0) and at the highest load (maximal cardiac rate) of an incremental exercise (W1); (2) in steady state conditions, at 50% of W1 (W1/2) and at 2/3 of W1 (W2/3). VO2BW, VT BW, VE BW, TI/TTOT, VT BW/TI increased significantly (P less than 0.01) from W0 to W1. Behaviour of f and TI were different from the latter parameters: f increased and TI decreased significantly from W0 to W1/2 (P less than 0.01) and from W1/2 to W2/3 (P less than 0.01) but remained similar at W2/3 and W1. We observed a relationship between VO2 BW and VT BW/TI, and between VT BW and TI/TTOT at each step of workload. We conclude that untrained children adapt the pattern of breathing during exercise, as at rest, to metabolic demand. However, the increase in f and the decrease in TI are limited at maximal workload.

Pulmonary function at 1 year of age in survivors of neonatal respiratory distress: a multivariate analysis of factors associated with sequelae

We studied pulmonary function 1 year after neonatal respiratory distress (RD) in 54 infants who had been treated at birth in the same neonatal intensive care unit. RD was related to hyaline membrane disease in 36 cases (group I) and to other causes in 18 cases (group II). Compared with predicted values, dynamic lung compliance (CL) was lower (less than -2 SD) and total pulmonary resistance (RL) was higher (+2 SD) in 18 (33%) and 12 (22%) infants, respectively. The relationships between these functional abnormalities at 1 year of age and the characteristics of the neonatal respiratory disease were assessed using a multifactorial analysis (multiple correspondences analysis). We found that elevated RL (greater than +2 SD) at 1 year of age was very significantly related with hyaline membrane disease, involving both high rate of positive pressure ventilation and prolonged intubation, and with the presence of both tachypnea and abnormal chest X rays at the time of discharge. Compared with elevated RL, the relationships between low CL (less than -2 SD) and the same neonatal characteristics were less significant; in particular, there was no strong link between low CL and hyaline membrane disease. Finally, birth before 30 weeks gestation was an index of severity.

Resting lung function in children after repair of tetralogy of Fallot

Children with tetralogy of Fallot had pulmonary function tests (PFT) after intracardiac repair (ICR). According to the age at time of ICR and to the existence or not of palliative surgery preceding ICR, they were divided into three groups. Group 1 had ICR at a mean of one year one month of age (range four months to one year seven months), that is, during the active period of postnatal lung growth. Groups 2 and 3 had ICR later in childhood, that is, respectively, at four years seven months (range two years nine months to 11 years 9 months) and at five years four months (range two years seven months to 11 years five months). In group 3, ICR was preceded by palliative surgery. The PFT at rest included measurement of lung volumes (functional residual capacity), vital capacity (VC), dynamic or static compliance (CL), total pulmonary resistance, lung transfer factor for CO (TLCO) and blood gases. Group 1 had normal lung function suggesting that early repair of TOF saves lung development. In groups 2 and 3, significant decrease in VC(p less than 0.01) and CL (p less than 0.01) were found suggesting impaired alveolar growth. Additional defect in TLCO (p less than 0.01) in group 3 suggested that palliative surgery induces abnormal vascular growth. Thus, the present functional results suggest repair of TOF during the two first years of life, ie, the active period of postnatal lung growth.

[Respiratory function during wakefulness and sleep in a 7-year-old child with congenital alveolar hypoventilation of central origin]

Pulmonary function tests were performed in a 7 year-old girl with central alveolar hypoventilation syndrome treated with mechanical ventilation during sleep. Results showed: 1. during wakefulness decrease in residual functional capacity, in dynamic lung compliance and in lung transfer factor for CO; 2. during sleep the characteristics of the syndrome as reported in the neonatal period i.e. central alveolar hypoventilation in stages 2 and 3-4 which justified maintenance of mechanical ventilation when asleep.

Lung mechanics and breathing pattern during wakefulness and sleep in children with enlarged tonsils

Thirteen children (mean age, 45 months) with nocturnal symptoms of upper airway obstruction, the result of enlarged tonsils, were tested during wakefulness (W) and sleep (S) induced by chloral hydrate (less than or equal to 50 mg/kg). During W, lung mechanics, blood gas, breathing pattern, and airflows during tidal breathing were in the normal range. During S, total lung resistance increased significantly, and dynamic lung compliance and transcutaneous PO2 decreased significantly. During S, the tidal volume (VT) and the mean inspiratory flow, normalized for body weight (BW), decreased whereas the ratio of the inspiratory time (TI) over the total duration of the respiratory cycle (TTOT) rose, indicating a longer contraction time of the respiratory muscles. The time to reach peak inspiratory flow, measured as a percentage of TI (dTI/TI), increased in seven children, with no change in the ratio of the expiratory flow over the inspiratory flow, both measured at 50% of VT (EF50/IF50). In three other patients dTI/TI decreased with an increase in EF50/IF50. We conclude that in children with enlarged tonsils, S modified lung mechanics, gas exchange, and the inspiratory components of the breathing pattern and airflow.

Lung functional follow-up in children after severe viral infection

Pulmonary function tests (PFT) were performed in 12 children after viral infection (VI) due to an adenovirus in 9 cases and occurring before the age of 4 in 10. Functional residual capacity (FRC), thoracic gas volume (TGV), total lung resistance (R1), dynamic lung compliance (C1dyn), expiratory flows and blood gases were measured during three periods after VI: from 3 to 12 months (n = 10), from 1 yr 6 months to 3 yr 8 months (n = 8), and from 4 yr 7 months to 8 yr (n = 6). In the short term period one child had normal PFT, while in the remaining cases there was increased R1, decreased C1dyn and hypoxemia. R1, C1dyn and blood gases did not significantly change between short and mid term periods. In the long term period the children had overinflation with trapped gases, airways obstruction and hypoxemia. These functional sequelae may be related to structural lesions due to VI and abnormal postnatal lung growth.

Comparison of transcutaneous and alveolar partial pressure of carbon dioxide during carbon dioxide breathing in healthy children

In 18 healthy children three to 13 years of age, the transcutaneous partial pressure of carbon dioxide (PtcCO2) (Radiometer electrode) and the alveolar partial pressure of carbon dioxide (PACO2) (Beckman analyzer) were measured simultaneously during the breathing of room air and 5 percent carbon dioxide. The PtcCO2 electrode was placed on the anterior thorax and heated to 42 degrees C. The PACO2 was calculated on the 4/5 part of the carbon dioxide expired trace. Minute ventilation (VE) was measured in 11 cases. There was a significant correlation between PtcCO2 (in millimeters of mercury) and PACO2 (in millimeters of mercury) while breathing room air (PtcCO2 = 0.82 PACO2 + 19.7; r = 0.55; p less than 0.02) and while breathing 5 percent carbon dioxide (PtcCO2 = 0.77 PACO2 + 22.5; r = 0.61; p less than 0.01); however, the ratio of PtcCO2 over PACO2 was significantly lower while breathing 5 percent carbon dioxide (p less than 0.01) than while breathing room air. When considering the relationship between the increase in VE (delta VE while breathing 5 percent carbon dioxide and the changes in PACO2 (delta PACO2) or in PtcCO2 (delta PtcCO2), a significant correlation was found only between delta VE and delta PACO2, ie, delta VE = 0.41 delta PACO2 + 0.44 (r = 0.63; p less than 0.01). These results suggest that breathing carbon dioxide modified the factors acting on PtcCO2, possibly by changes in the vasomotor tone of cutaneous blood vessels. These modifications appeared to be variable from subject to subject. Therefore, we conclude that PtcCO2 does not appear to be an accurate quantitative index to assess ventilatory response to carbon dioxide.

Lung function in children with hypersensitivity pneumonitis

Pulmonary function tests were performed on 12 children with hypersensitivity pneumonitis (HP) aged from 4-15 years (10 with bird breeder's lung and 2 with farmer's lung). Lung volumes, lung mechanics (lung resistance, dynamic lung compliance (CLdyn], lung transfer factor for CO (TLCO), and blood gases were measured. Eleven children ceased to be exposed to the antigen, and the functional course was studied as a function of time after the cessation of exposure (CE). During the short term (less than 2 months after CE) initial hypoxemia was observed and CLdyn and TLCO were below normal. Two months after CE, blood gases were normal in most of the cases. A persistent hypoxemia appeared to be an unfavorable prognostic factor. CLdyn was normal by the eighth month after CE, while TLCO improved more slowly and remained significantly decreased in one case. In our series the children under 10 years had less functional abnormalities and normalized more rapidly than the older children. The one child without CE, had major functional abnormalities.

[Sustained-action oral theophylline in the asthmatic child. Clinical, pharmacokinetic and respiratory function studies]

Twenty children aged between 5 and 16 suffering from severe asthma were treated with long acting oral theophylline. The minimum duration of treatment was three months and the maximum 12 months. Clinical, pharmacokinetic and pulmonary function studies were made. With a mean dose of 8.75 mg/kg, morning and evening, the theophylline blood levels on the 4th day of treatment (4 hours after the morning dose) were 12.3 +/- 4.36 mg/l. Those taken 4 hours after the evening dose 9.41 +/- 3.75 mg/l, suggesting a circadian rhythm for theophylline blood levels. The importance if fever is stressed in relationship to blood levels, which were increased by 67-100% with fevers of 38.5-39 degrees C. Treatment was very beneficial in 53% of cases. Respiratory function studies were performed in 13 children. After 4 days of treatment there was a significant decrease in airflow obstruction and hypoxemia However, despite carefully adjusted treatment, functional disturbances persisted, in particular hyperinflation.

Control of breathing in children with interstitial lung disease

Control of breathing at rest was studied in 14 children (4-16 years old) with interstitial lung disease (ILD). Four of them were tested several times. Breathing pattern and the mouth occlusion pressure (P0.1) were measured. Results in ILD children were compared to values in healthy children previously reported. Respiratory frequency and minute ventilation were increased (P less than 0.02). Inspiratory time (TI) was shortened (P less than 0.001), the shortening in TI being significantly related to the increase in lung elastance (EL). The ratio of TI to the total duration of the respiratory cycle (TI/TTOT) was lowered (P less than 0.01). Tidal volume (VT) both in ml and normalized for body weight (BW) was normal. P0.1 was higher than predicted. The increase in P0.1 was significantly related to change in arterial O2 pressure (PaO2) which was reduced in 10 cases. There was a significant relationship between the increase in P0.1 and in EL. The increase in mean inspiratory flow (VTBW/TI) was related to the increase in EL. But VTBW/TI was not increased as much as P0.1. Consequently the effective inspiratory impedance was enhanced. This high effective inspiratory impedance was related to the increased lung elastance.

Occlusion pressure and breathing pattern in healthy children

The breathing pattern was investigated in 62 children aged 4 to 16 years together with the mouth pressure generated 0.1 s after an occlusion at the endexpiratory level (P0.1). A group of 20 adults (18 to 32 years old) were tested in a similar way. The values of P0.1 obtained during room air breathing at rest in the children decreased with age as a power function P0.1 = 8.51 A-0.62 (where A is age in years), r = -0.74. Adult values of P0.1 were achieved at about 13 years. After O2 inhalation P0.1 decreased in children, but the changes in P0.1 were independent of age. Respiratory frequency decreased with age while inspiratory time (TI) increased, both reaching adult values at about 13 years. The ratio of TI over the total respiratory cycle duration did not change significantly with age in the entire population. The absolute value of tidal volume (VT) increased with age, but not when normalized for body weight (BW). The mean inspiratory flow (VT/TI) normalized for BW decreased with age in children as did P0.1. There was a significant relationship between P0.1 and VT/TI normalized for body weight (r = 0.63).

[Successive courses of intensive therapy in cystic fibrosis (author's transl)]

Twenty-four patients aged from 3 to 30 years and suffering from advanced cystic fibrosis received several courses of intensive antibiotic therapy combined with prolonged respiratory physiotherapy with postural drainage. Antibiotics included carbenicillin 500 mg/kg/day and aminoglycosides in high dosage (6 mg/kg/day). These treatments were administered to prevent aggravation of chronic bronchitis and to suppress acute exacerbations. Tolerance was satisfactory, and all patients felt better, at least during the first courses. Improvement was also observed in the main respiratory function parameters. In a total of 95 courses only two side-effects (severe dizziness and giant urticaria) were recorded. Intensive courses of combined antibiotic therapy associated with physiotherapy constitute a new way of treating severe, progressive cystic fibrosis. The patients are made comfortable, and their survival time is increased by several years.

Lung function in children with recurrent bronchitis

Lung function was studied in 29 children suffering from recurrent bronchitis (average number of bronchitis attacks per year: 4.2 +/- 0.5). Most of them (73%) were 1--7 years old. The date of exploration in relation to the last acute bronchitis was on average 6 weeks. Lung mechanics, residual functional capacity, blood gases and regional lung function were measured. Most of the children were suffering from some kind of functional disorder; alteration of lung mechanics -- increase of lung resistance (22/29) decrease of dynamic compliance (15/23); increase of functional residual capacity (6/10), non specific bronchial hypersensitivity (12/17); regional ventilatory and perfusion malfunction. These functional disorders could be the first evidence of the bronchial lesions which cause chronic obstructive bronchitis in adults.

Neopallial Morphology of Fossil Men as studied from Endocranial Casts

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