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Biomedical subjects

C Gaultier

Publications and source records attributed to C Gaultier.

At least 163 records · Page 9Linked to original sources
PubMed1984

Abdominothoracic configuration and maximal static pressures in children.

The relationship of abdominothoracic configuration (AT config) to maximal static inspiratory and expiratory mouth pressure (Pimax, Pemax) was studied in 9 children. Pmax manoeuvres were performed from the relaxed end-expiratory position (FRC relax) and after contracting the abdomen (Abd) and expanding the rib cage (RC), (FRC isovol). Anteroposterior diameters (AP) of RC and Abd during Pmax were measured with magnetometers and compared to AT config at FRC relax. During both Pimax and Pemax from FRC relax the RC AP increased and Abd AP decreased. The pressures generated did not correlate with the change in either diameter. Moving to FRC isovol prior to the onset of pressure generation had no effect on AT config obtained for Pemax, but for Pimax resulted in further increase in RC AP and decrease in Abd AP as compared to FRC relax. Despite these differences in AT config, Pimax was not significantly affected. This suggests that changes in AT config expected to place the diaphragm at a mechanical advantage were countered by an opposite effect on the other inspiratory muscles. Because the AT config for Pemax was fixed, there appears to be a unique balance of forces between the expiratory muscles acting on the rib cage and the abdomen during a maximal static expiratory effort.

Abdomen↗
PubMed1984

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.

Airway Obstruction↗
PubMed1984

Lung mechanics in rachitic rats.

Lung mechanics was studied at 50 days of age in 7 rachitic rats born from mothers deprived of vitamin D. They were compared with 7 control rats raised in the same conditions but fed a diet supplemented with vitamin D. The animals were anesthetized, tracheotomized, and paralyzed. Quasi-static pressure-volume curves of the respiratory system and of the lungs were obtained. Body weight of the rachitic rats was within the range of the control rats, but dry lung weight (LW) was significantly lower (p less than 0.01). Lung volumes in absolute terms and when normalized for LW were significantly lower than in the control rats. Chest wall compliance (Ccw) of the rachitic rats was within the range of values of the control rats, except for 2 animals with an infinite Ccw. Analysis of the pressure-volume curves of the lungs of the rachitic rats compared with those in the control animals showed a significant decrease in lung compliance (CL) and in CL/LW (p less than 0.01), indicating a decrease in lung distensibility. The more severe the rickets (according to microradiographic criteria of the tibia), the lower the CL/LW. It is speculated that decrease in lung distensibility may be related to abnormal lung growth caused by disturbed alveolar formation and lung connective tissue development. These abnormalities could be due to vitamin D deficiency acting on the growing lung, as on the growing bones, by a mechanism involving proteoglycans.

Animals↗
PubMed1984

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.

Adolescent↗
PubMed1984

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.

Adolescent↗
PubMed1984

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.

Adolescent↗
PubMed1983

Maximal static pressures in healthy children.

Maximal static pressures (Pmax) were measured at the mouth in 119 Caucasian school children aged 7-13 years. Lung volumes were determined by body plethysmography. Pressures were generated near RV, at FRC and near TLC. As in adults, inspiratory Pmax decreased with increasing lung volume, whereas expiratory Pmax increased. At all lung volumes expiratory and inspiratory Pmax increased with age and were greater in males than females. Net respiratory muscle force was derived from the product of pressure and surface area (SA) over which pressure was applied. SA was estimated at different lung volumes on the basis of chest wall measurements. The dimensions obtained were utilized to calculate the SA of a truncated cone. This model was shown to be appropriate at TLC and FRC, but not RV. Since both SA and Pmax increased with age, the derived forces, as compared with pressures, proportionally increased more with age. Thus changes in Pmax underestimated changes in force during growth.

Adolescent↗
PubMed1983

[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.

Administration, Oral↗
PubMed1982

Effects of chest wall compressions in kittens.

Effects of chest compressions on the pattern of breathing were studied in pentobarbital anaesthetized 9- to 11-day-old kittens before and after vagotomy. The chest was compressed by means of a micrometer at three levels (T1-4, T6-8, T9-11). In intact and vagotomized kittens, the group mean values of inspiratory time (tI), expiratory (tE) time, peak amplitude of the integrated phrenic activity (PHR) and its rate of rise (PHR/tI) during compressions were not different from those of the control breaths. On the other hand, in intact kittens during chest compressions variability of all the measured variables significantly increased. In the vagotomized kittens, variability of parameters other than inspiratory time was unaffected. Nevertheless we cannot exclude contribution of extravagal receptors in control of tE. The tE effects could be masked by the increased variability of the control value in vagotomized kittens. The effects of chest compression on the integrated phrenic activity were mostly dependent on the intact vagal feedback.

Animals↗
PubMed1982

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.

Adolescent↗