Biomedical subjects

P Baconnier

Publications and source records attributed to P Baconnier.

23 records · Page 2Linked to original sources

PubMed1983

Simulation of a biological oscillator: the respiratory system.

Several models of oscillators defined by a system of non-linear differential equations have been built which simulate quite well some entrainment characteristics of the respiratory system: the range of entrainment, positioning of the stimulus at entrainment and the variation of inspiratory duration with entrainment periods. The construction of the model has been guided by consideration of the isochron configuration and the phase response curve of the system, which may yield a good qualitative fit between simulation and experimental results.

Animals↗

PubMed1983

[New elements in the interpretation of flow-volume curves].

We have measured flow-volume curves (FV) in 167 normal individuals of both sexes aged 20 to 89. All were non-smokers and none had cardio-respiratory disease. The flows at 25, 50 and 75 per cent of vital capacity (VC) as well as flows normalized by VC or total lung capacity (TLC) gave, in general, good correlation coefficients with age. The parameters V25/TLC and especially V50/TLC gave for the best correlations with age and we suggest these parameters in future when flow volume curves are used to assess respiratory pathophysiology. Normal values as well as regression equations of these parameters with age are proposed for various age groups in the 20-89 years age range.

Adult↗

PubMed1979

Liver heat production and temperature regulation in the anesthetized dog.

Liver heat production (LHP) was measured in the anesthetized dog by a new calorimetric method. Blood flows and temperatures were measured at the same points. The method avoided damage of liver innervation and vascularization. Changes of LHP were investigated under different thermal conditions. Measurements at controlled arterial temperatures within the physiological range showed changes of LHP when arterial temperature was randomly increased or decreased. When measured LHP was compared in experiments carried out at different ambient temperatures, a negative linear correlation was found between LHP and the ambient temperature. It was concluded that liver heat production may be a factor in temperature regulation.

Animals↗

PubMedDate not supplied

Effect of acute hypoxia on lung fluid balance in the prerecruited dog lung.

Lung lymph flow and protein transport were measured in eight anaesthetized dogs while acute hypoxic exposure (FIO2 = 0.10) was performed on prerecruited lung (achieved by an increased left atrial pressure). It was found that the lung lymph flow increase observed during hypoxia (from 71.8 +/- 47.5 to 100.8 +/- 78.4 microliters X min-1; p less than 0.05) was associated to an unchanged lymph/plasma protein concentration ratio (from 0.60 +/- 0.9 to 0.60 +/- 0.11). During recovery from hypoxia, lymph flow remained at a higher level than before hypoxia (respectively 87.8 +/- 49.5 and 71.8 +/- 47.5 microliters X min-1). These results suggest that the mild hypoxia-induced oedema is rather a high permeability oedema than an haemodynamic oedema. A graphic representation of protein clearance changes versus lymph flow changes was used in order to discriminate between high permeability and haemodynamic oedemas at their early stage.

Animals↗

PubMedDate not supplied

Effect of acute hypoxia on lung transvascular filtration in anaesthetized dogs.

The pulmonary transvascular filtration changes were investigated in nine anaesthetized open-chest dogs during acute hypoxic exposure. The tracheobronchial pulmonary lymph flow, the lymph and plasma protein concentration, the pulmonary vascular pressures and the cardiac output were measured during three consecutive steady states of about 2 h each: 1) base-line, 2) hypoxia (FIO2 = 0.10), 3) recovery from hypoxia. It was found that pulmonary arterial pressure and lung lymph flow increased in all animals during hypoxia, respectively from (average +/- SD) 19.4 +/- 4.5 to 27.1 +/- 5.6 Torr, and from 27.2 +/- 10.2 to 59.8 +/- 23.8 microliters . min-1; lymph to plasma protein concentration ratio remained unchanged. During recovery, lung lymph flow remained elevated in some animals, while it returned to its initial value in the others. Control experiments with normoxic hyperventilation in five dogs showed no increase in lymph flow. The extravascular water/blood free dry lung ratio was moderately increased in animals that had been made hypoxic (4.64 +/- 0.67) compared to a control group (3.46 +/- 0.36). These results suggest that acute hypoxic exposure causes an increased pulmonary transvascular filtration in anaesthetized dogs.

Acute Disease↗