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Biomedical subjects

C Grimaud

Publications and source records attributed to C Grimaud.

At least 109 records · Page 6Linked to original sources
PubMedDate not supplied

[Role of the acid-base status on the changes of haemoglobin oxygen affinity in arterial hypoxemia (author's transl)].

Fifty-seven patients, all with chronic respiratory insufficiency and hypoxemia, have been classified in five groups according to their acid-base status, determined by the intra-erythrocytic pH (pHi) : A. normal acid-base balance ; B. chronic alkalosis ; C. acute alkalosis ; D. acute acidosis ; E. chronic acidosis. We have measured in the arterial blood : Po2, PCO2, plasmatic pH (pHp1), pHi, P50(7,40) and 2,3-DPG. From these values. the base-excess (B.E.) and the P50 to real pH [P50 I.V.] have been computed. There is a good correlation between 2,3-DPG and P50 (r = 0.707), none between P50 and Pao2. For a normal acid-base balance, P50 and 2.3-DPG also are normal. Increased in chronic alkalosis, the amount of DPG is decreased in chronic acidosis. The DPG-pHi correlation is very good (r = 0.691 ; pless 0.001) and the changes of the acid-base balance seem to be the main factors for controlling the DPG synthesis : it increases it in chronic alkalosis and reduces it in chronic acidosis. Thus the P50(I.V.) returns to the normal range on account of the Bohr effect adjustement. On the contrary, in acute acidosis and alkalosis, the amount of DPG is normal and the P50(I.V.) is increased or reduced. Therefore the duration of the acid-base lack of balance also interfers.

Acid-Base Equilibrium↗
PubMedDate not supplied

Breathing discomfort in asthma: role of adaptation level.

In asthmatic patients, Helson's adaptation level theory was applied to breathing discomfort to investigate the discrepancy between the subjective severity of breathlessness and their objective airflow obstruction. The data from a signal detection methodology show a considerable loss of sensitivity in twelve asthmatic patients with permanent airflow obstruction compared to the high sensitivity of six normal subjects to the same four external resistive loads (range 2.5 to 8.0 cmH2O X l-1 X s). Furthermore, when subjective ratings are examined, the absence of any contrast effect between adjacent load intensities in asthmatics suggests that these subjects evaluate the discomfort induced by the loads with reference to a strong internal comparison (adaptation level) rather than to the experimental stimuli. There was no relationship between physiological parameters and the low sensitivity of asthmatics. Also salbutamol-induced bronchodilation in six asthmatics did not improve sensitivity or induce any contrast effect. These two observations bring out the necessity to consider the role of past experience of breathing discomfort on adaptation level and sensitivity.

Adaptation, Physiological↗
PubMedDate not supplied

Increased ventilatory chemosensitivity induced by domperidone, a dopamine antagonist, in healthy humans.

Respiratory and cardiovascular effects of domperidone (0.1 mg X kg-1 i.v.) and placebo given on separate test days to eleven healthy volunteers were assessed in a double-blind study. Domperidone caused no significant change in ventilation, heart rate and blood pressure while they were resting and breathing room air. However, it produced an increase in the slope of the hypoxia-induced ventilatory response, from 2.35 +/- 1.10 to 3.71 +/- 2.91 1 X min-1 per 1% decrease in SaO2 (mean +/- SD; p less than 0.05). We conclude that domperidone augments hypoxic responsiveness in humans, presumably by blocking the dopaminergic receptors that modulate the activity of carotid body chemoreceptors, as it does not readily cross the blood-brain barrier.

Adult↗
PubMedDate not supplied

Effects of airflow resistance variations on resistive load detection in normal subjects.

The sensitivity to airflow resistance variations produced by externally added resistive loads, with modification of background load, was studied in 15 normal subjects, using "Sensory Decision Theory" (SDT), a psychophysical method that gives an index of accuracy, P(A), unaffected by response bias. In six subjects, asked to detect three increasingly added loads (delta R) at different levels of basal resistance (1.6 and 3.6 cmH2O X 1(-1) X s), inspiratory resistive load detection (RLD) improved with background loading, and a highly significant relationship was found between P(A) and peak mouth pressure (Pm). The relationship between P(A) and the change in Pm, i.e. delta Pm, was less significant. These results suggest that, although tension developed by the respiratory muscles reflected by mouth pressure may be an important stimulus to respiratory RLD, other factors must also be considered. In seven subjects, in whom airway resistance was increased at least 50% by inhalation of carbachol, inconsistent variations in P(A) were found. In seven subjects, in whom airflow resistance was decreased by inhalation of heliox, and in six of seven subjects after salbutamol inhalation, RLD was significantly impaired. The results of this study lead us to the conclusion that Weber's law is not verified for weak internal or external background loading.

Adult↗