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Biomedical subjects

C Gaultier

Publications and source records attributed to C Gaultier.

At least 73 records · Page 4Linked to original sources
PubMed1995

[Bronchopulmonary dysplasia: outcome and treatment of severe forms].

BACKGROUND: The outcome of severe forms of bronchopulmonary dysplasia (BPD) leading to a prolonged dependence on mechanical ventilation (MV) and/or oxygen therapy (O2) is not evaluated, and factors of guidance to treatment are not established. POPULATION AND METHODS: The medical records of 49 infants, born between 1982 and 1990, with BPD who required MV and or O2 after 12 months of life were retrospectively reviewed. Three groups of infants were defined: group I: 26 infants on MV since birth; group II: seven infants weaned from MV after the first month of life then put back on MV belatedly; group III: 16 infants on spontaneous ventilation (SV) under O2. RESULTS: At 12 months of age, the 49 infants showed sleep hypoxemia, failure to thrive and 28% of them pulmonary hypertension. Comparison between MV and O2 infants indicated that subjects on MV had pulmonary dynamic compliance (Cl dyn) lower than 50% (p = 0.01), ventilatory work including respiratory frequency in rest > 40 cycles/min; 70% of them had asynchronous thoracic and abdominal muscles during sleep (p < 0.01 for all comparisons). Seventy percent of patients had bronchospasms (p = 0.02). The 49 infants had a favourable outcome, allowing weaning from MV or O2 between the ages of 2 and 4 years. CONCLUSIONS: These findings suggest that major respiratory failure in prematurely born infants can be overcome with prolonged respiratory and nutritional supports during the post-natal period of lung development; Cl dyn < 50% is a cursor for prolonged MV and weaning from MV should be excluded as long as increased ventilatory work persists.

Bronchopulmonary Dysplasia↗
PubMed1995

Oxygen cost of breathing in newborn infants with long-term ventilatory support.

Oxygen consumption (VO2) was measured during controlled and spontaneous ventilation with continuous positive airway pressure in newborn infants in whom chronic lung disease later developed. The oxygen cost of breathing (the difference in VO2 between spontaneous and controlled ventilation) was significantly higher in infants with chronic lung disease than in control infants (20.1% +/- 7.5% and 4.8% +/- 4.9% of VO2 during spontaneous ventilation (p < 0.05), respectively).

Age Factors↗
PubMed1995

Sleep-related breathing disorders. 6. Obstructive sleep apnoea syndrome in infants and children: established facts and unsettled issues.

The presence of increased upper airway resistive loads during sleep can now be diagnosed by paediatricians. However, diagnostic criteria need to be further clarified to allow accurate identification of episodes of partial airway obstruction. New technological advances can be expected to help to determine the clinical usefulness of ambulatory testing during sleep and thus to establish the indications for polysomnographic investigations in the laboratory. A thorough investigation of the anatomical abnormalities that contribute to airways obstruction is essential for selecting the most appropriate therapy. However, the order in which these investigations should be performed remains unclear. The diagnostic tools, including questionnaires and sleep testing, and methods aimed at investigating pathophysiological mechanisms should be standardised for multicentre studies. Familial factors should be taken into account. The best strategy for preventing the complications of the OSA syndrome is to identify the disorder as early as possible. This requires close cooperation between adult physicians and paediatricians called upon to evaluate sleep-related disorders.

Adolescent↗
PubMed1995

Effect of state of alertness on the heart rate response to ocular compression in human infants.

Because the state of alertness exerts a profound influence on autonomic cardiac control, we hypothesized, that the heart rate response to a vagal stimulus, i.e., ocular compression, may differ during different states of alertness. We studied 8 healthy infants with a postconceptional age of 35-41 weeks (mean +/- SD 37.9 +/- 2.1 weeks). They underwent a standardized ocular compression test during polygraphically controlled wakefulness, rapid eye movement (REM) sleep, and non-REM (NREM) sleep. The R-R intervals were measured (1) during the 60 s preceding the ocular compression test, to determine the mean control R-R interval, and (2) during compression. Percent R-R interval was defined as the longest R-R interval in milliseconds during the test divided by the mean control R-R interval and multiplied by 100. The longest R-R interval during the test was significantly greater in REM sleep than in wakefulness (p < 0.05) and in NREM sleep (p < 0.01):939 +/- 360, 623 +/- 355, and 538 +/- 60 ms, respectively. The percent R-R interval was significantly greater in REM sleep than in NREM sleep (p < 0.01):236 +/- 91 and 129 +/- 16, respectively. The time from the longest R-R interval to return to mean control R-R interval, i.e., vagal escape, was significantly shorter in REM sleep than in NREM sleep and in wakefulness (p < 0.01): 843 +/- 168, 2,131 +/- 712, and 2,078 +/- 913 ms, respectively. This study indicates that the state of alertness should be defined when performing tests on autonomic reflexes in infants.

Autonomic Nervous System↗
PubMed1995

Respiratory muscle function in infants.

In newborns and infants a variety of respiratory disorders lead to ventilatory failure. In early life the ventilatory response to loaded breathing is limited. The risk factors of ventilatory failure are related to the developing respiratory pump because of the immaturity of the chest wall, respiratory muscles and coupling between thoracic and abdominal movements. Assessment of respiratory muscle function in infants is limited, due to the objections to using invasive techniques. However, measurement of airway pressures during crying may provide an index of respiratory muscle strength in infants. Real-time ultrasonography allows investigation of diaphragmatic movements. Pattern of thoracoabdominal motion can be assessed using uncalibrated respiratory inductive plethysmography. Finally, electromyographic recording of respiratory muscles by surface electrodes is of clinical usefulness during sleep studies.

Humans↗
PubMed1995

Cardiovascular changes during acute episodic repetitive hypoxic and hypercapnic breathing in rats.

It has been shown that chronic repetitive ambient hypoxia, simulating pulmonary gas disturbances observed in apnoea, leads to systemic hypertension in rats. However, the relative roles of hypoxia (HO), hypercapnia (HC), gas stress and vigilance on the cardiovascular changes have not yet been demonstrated. The aim of this study was to investigate the acute haemodynamic changes observed during the repetitive inhalation of various gas mixtures in rats for HO alone and HO+HC, and to analyse the effects of vigilance and of the stress of gas administration. We studied 6 unanaesthetized Wistar rats chronically instrumented with an aortic catheter. Nitrogen, nitrogen+CO2 mixtures and compressed air were randomly administered in a Plexiglass chamber for 10 s and then flushed by compressed air for 20 s. Two cycles were repeated every min for 10 to 12 min. The inhaled gas fractions (FI,O2,FI,CO2) were monitored by O2 and CO2 analysers. Blood pressure (BP) was measured by a P23XL transducer. The blood gases were analysed by a 1306 IL meter. In control experiments, with compressed air alone, there were no significant acute changes in heart rate (HR) and BP. During HO there were no changes in HR or BP at FI,O2 values from 0.05-0.14, whilst at FI,O2 values from 0-0.05 systolic blood pressure (SBP) rose significantly (+25.3 +/- 25.7 (SD) mmHg) and HR decreased (-93.8 +/- 124.1 bpm). During HOHC, SBP rose (+35.1 +/- 26.4 mmHg) and HR decreased (-139.3 +/- 75.7 bpm), significantly more than in HO alone. SBP was linearly correlated with Pa,O2 during HO (r = 0.53) and also during HOHC (r = 0.44) and was not directly related to Pa,CO2 which has, nevertheless, an additive effect to HO. SBP rose with each challenge significantly more when the rats were awake than when asleep (behavioural sleep). We conclude that in this acute repetitive inhalation model, the rise in SBP is not related to gas stress or to Pa,CO2 but to a decrease in Pa,O2 and is enhanced by wakefulness.

Acute Disease↗
PubMed1995

[Growth and ventilatory function in Black children and adolescents].

The authors realized an anthropometric and spirometric study in Senegalese children and adolescents, 119 males and 82 females were selected. They studied the statural and thoracic rate of growth with age and the consequences on lung function growth. The correlations between each spirometric parameter and each anthropometric parameter were calculated in order to determine the best regression equations of pulmonary volumes and flows according to height, weight and other anatomical parameters. Results were compared to literature. The spirometric values were very close to Black American and African ones but the spirometric volumes were about 20% less than Caucasian values. The differences in forced expiratory flows were smaller (10%). The explanation is mainly anatomic: African children have smaller thorax with long limbs as it was shown largely in adults. The rate of somatic and lung growth was not similar to Caucasian children, thus we have proposed our regression equations as spirometric reference values for African children and adolescents.

Adolescent↗
PubMed1995

Long-term pulmonary sequelae after autologous bone marrow transplantation in children without total body irradiation.

We investigated the long-term pulmonary sequelae of 38 children surviving 3 to 11.5 years (median 7 years) after high-dose chemotherapy (HDC) and autologous bone marrow transplantation (ABMT) without TBI. This cross-sectional study included patients with neuroblastoma (21), non-Hodgkin's lymphoma (7), Ewing's sarcoma (5), rhabdomyosarcoma (3), medulloblastoma (1) and ALL (1). They were asked and examined for clinical signs and underwent a physical examination with chest X-ray; 33/38 had pulmonary function tests (PFT) performed. No obstructive disease was found. Fifteen out of 32 evaluable PFT (47%) were abnormal with a pulmonary restrictive syndrome in 10, and borderline values in five patients. Four of these 15 patients were symptomatic with exertional dyspnea and two of four had abnormal chest X-rays. The etiology was mainly multifactorial, associating HDC with thoracic radiotherapy +/- scoliosis/kyphosis +/- previous thoracotomy +/- post-ABMT interstitial pneumonitis. Only 3/10 patients with a restrictive syndrome had HDC containing BCNU or busulfan as the only risk factor for lung disease. We conclude that the prevalence of late pulmonary sequelae after ABMT without TBI is moderate and rarely due to HDC alone, since most abnormal PFT can be explained by heavy pretreatment prior to ABMT. As symptoms are scarce even in advanced disease, repeated testing and very long-term follow-up are needed.

Adolescent↗
PubMed1994

Measurement of oxygen uptake in newborn infants during assisted and spontaneous ventilation.

Measurements of oxygen uptake (VO2) and CO2 output (VCO2) are useful in critically ill patients. However, VO2 is not routinely measured in intensive care during mechanical ventilation (MV) especially in premature newborns. The present study describes a new method of measuring VO2 and VCO2 using a double open circuit which accounts for gas leaks around the uncuffed tracheal tube. The accuracy of the method was assessed with N2 and CO2 infusion. In case of leaks, VO2 and VCO2 measurement was significantly underestimated by the simple circuit method. This underestimation was not present with double circuit method. Five preterm newborns were studied. VO2 and VCO2 using the double open circuit were compared with the classic simple circuit. During MV, the mean underestimation assessed by the difference between simple and double circuit measurement was -12% (range from 0 to -29%) for VO2 and -14% (range 0 to -26%) for VCO2.

Carbon Dioxide↗
PubMed1994

[Upper airway muscles and physiopathology of obstructive sleep apnea syndrome].

Upper airway dilator muscle generate inspiratory pressure that balances subatmospheric pharyngeal pressure gene-rated by diaphragmatic contraction leading to reduce upper airway patency. Neural control of upper airway dilator muscles involve several categories of receptors such as vagal pulmonary receptors, upper airway mecanoreceptors, baroreceptors, chemoreceptors. Upper airway resistances increase during sleep and upper airway inspiratory muscle activity decrease especially during bursts of rapid eye movements in REM sleep. Sleep-related upper airway obstruction occurs when upper airway dilator pressure does not balance subatmospheric pharyngeal pressure. Several variables are involved in the pathophysiology of obstructive apneas such as upper airway anatomical factors, structural muscular dysfunction, changes in neural drive.

Animals↗
PubMed1994

Apnea and sleep state in newborns and infants.

Many studies have shown a greater frequency of apneas in active sleep than in quiet sleep in healthy newborns and infants, both full-term and preterm. The ontogeny of increased apnea during active sleep is related to phasic inhibitory-excitatory central mechanisms occurring during active sleep. Respiratory instability in active sleep can be increased by factors which modify the newborn's or infant's homeostasis. We have shown: (1) an increase in body temperature (0.8 degrees C) significantly augments periodic breathing in preterm infants at 40 weeks postconceptional age; (2) maternal administration of meperidine is followed by a significant increase in number of apneas during the first hours of life in full-term newborns, but only during active sleep; (3) sleep deprivation induces significantly more obstructive respiratory events in active sleep than in quiet sleep in infants. Active sleep appears to be a risk period for exaggeration of the occurrence of apneas when the newborn's or infant's homeostasis is disturbed.

Body Temperature↗
PubMed1994

Heart rate variability during sleep in infants with bronchopulmonary dysplasia. Effects of mild decrease in oxygen saturation.

We sought to determine whether abnormal heart rate modulation by the autonomic nervous system occurs in patients with severe bronchopulmonary dysplasia (BPD) in relation to sleep stages and mild changes in arterial oxygen saturation SaO2. On 10 oxygen-dependent 7- to 29-month-old infants with BPD, polygraphic recordings, including heart and respiratory rate and body movement detection, were performed. Heart rate variability was evaluated in high (HF), mid, and low (LF) frequency bands. Parameters were analyzed in two ranges of SaO2: normal range, (SaO2 greater than 95%), and mild decrease in (SaO2, values of 90 to 94%). In contrast to what is normally observed, LF at normal SaO2 was less marked in rapid eye movement, (REM) sleep than in non-rapid eye movement (NREM) sleep stage 2. A mild decrease in SaO2, as compared with a normal SaO2 value, was associated with: (1) a heart and respiratory rate acceleration, (2) a decrease in HF in REM sleep (p < 0.02); (3) an increase in LF in NREM sleep stage 2 (p < 0.02), intensifying the change observed in a normal SaO2 level. These data show that a mild decrease in SaO2 increases modifications of autonomic control observed in infants with severe BPD.

Bronchopulmonary Dysplasia↗
PubMed1993

Ventilation and thoracoabdominal asynchrony during halothane anesthesia in infants.

To evaluate the ventilatory consequences of high chest wall compliance during anesthesia in infants, we assessed the effects of halothane at different fractions of minimal alveolar concentration (0.75, 1.0, and 1.5 MAC) on ventilation and movements of the rib cage and abdomen in infants < or = 12 mo of age (group I) and children (group II) > or = 12 mo of age. Minute ventilation decreased in group I, (20.6%, 0.75 to 1.5 MAC), but the change in group II did not reach the level of statistical significance. Tidal volume decreased with halothane level between 0.75 and 1.5 MAC, and its fall was greater in group I (32.7 +/- 11.2 vs. 22.6 +/- 9.3% in group II, P < 0.05). Duty cycle, or ratio of inspiratory to total time (TI/TT), increased in group II with halothane level but did not change in group I, resulting in a decreased TI in group I at higher halothane levels. Thoracic paradox increased with halothane level in group I but not group II. The increase in thoracic paradox in association with the fall in tidal volume between 0.75 and 1.5 MAC was greater in group I than group II (P < 0.05). We conclude that smaller infants depend more on inspiratory intercostal muscle activity to stabilize the thorax, leading to a greater degree of depression of ventilation during halothane depression of inspiratory intercostal activity.

Abdominal Muscles↗