Preserved CO2 response in cerebral and muscular blood vessels during cimetidine treatment.

It is known that cimetidine inhibits the hypoxia-induced increase in cerebral blood flow (CFB) in dogs, but the mechanism of this inhibition is not fully understood. Since the accepted mechanisms explaining the increase in CBF during hypercapnia are very different from those active during hypoxia, acute hypercapnia was induced in 12 conscious dogs in order to study the cimetidine effect in this condition. Six dogs were given i.v. saline (control group) and the other six, i.v. cimetidine (4 mg kg-1). After 15 min, CBF and various muscular blood flow measurements were performed, using the microspheres technique under two conditions: (1) breathing air and (2) after 2 h inhalation of a gas mixture with FiCO2 0.10, FiO2 0.21 in nitrogen. The CBF increase was similar in both series with or without cimetidine. The changes in muscular blood flow were unaffected by the H2-blocker. We conclude that cimetidine has no effect on the CBF and on muscular blood flow during acute hypercapnia.

[Littler's operation (SORL = spiral oblique retinacular ligament) in the treatment of "swan neck"]. / L'opération de Littler (SORL = spiral oblique retinacular ligament) dans le traitement du "col-de-cygne".

The surgical treatment of "swan-neck" deformities secondary to mallet finger using Littler's technique (Spiral Oblique Retinacular Ligament) in a series of 35 cases, led to a complete correction of the PIP joint hyperextension in 95% of the cases and a correction of the DIP joint flexure in 70% of the cases. This active tenodesis restores the physiology of the extension of the PIP and DIP joints as far as the surgical technique has been strictly respected.

[Miniaturized osteosynthesis of articular fractures of the fingers. Results of a series of 60 cases]. / Ostéosynthèse miniaturisée des fractures articulaires des doigts. Résultats d'une série de 60 cas.

The importance of anatomical reduction of articular fractures and early mobilisation of these severe forms of trauma which frequently damage the extensor apparatus (58% of cases, led us to propose direct miniaturised osteosynthesis as described by the Nancy-Strasbourg team. Of the 1,000 cases of osteosynthesis performed between 1978 and 1985, we selected 12 fractures of the MP joint, 38 fractures of the PIP joint and 10 fractures of the DIP joint, differentiated into 4 stages according to the condition of the skin and tendons and into 9 categories according to the anatomical type and the site of the fracture. Direct osteosynthesis (screw, bolt, pin) was used in every case. The clinical results were evaluated in terms of the Total Active Range of Movements, the local trophic state, the amount of pain and return to work, for each joint. When well conducted and with effective skin cover, this technique allows almost normal reconstruction in simple fractures and is valuable in more complex fractures by preserving sliding of the tendinous apparatus due to early mobilisation.

Cimetidine inhibits the hypoxia-induced increase in cerebral blood flow in dogs.

Cimetidine is an H2 receptor-blocking drug frequently given to ICU patients for the prevention of stress ulcers. However, histamine causes potent cerebral vasodilation through the H2 receptors. This study tested the hypothesis that cimetidine, by blocking the H2 receptors, could blunt the increase of cerebral blood flow induced by hypoxia. We induced isocapnic hypoxia in 12 conscious dogs that were randomly divided into two groups. Six dogs received no treatment (control group), and the other six received iv cimetidine (4 mg/kg) to block the H2 receptors. Cerebral blood flow (CBF) was measured with the radioactive microsphere technique before, and 2 and 4 h after hypoxia was induced. In the control group, CBF significantly increased with hypoxia in all the regions of the brain. Cimetidine blunted this increase in all the regions of the brain except the pons and bulb. As a result of the reduced flow, cimetidine significantly decreased the oxygen supply to the brain compared to the control group. We conclude that cimetidine blunts the increase in CBF during hypoxia and might reduce oxygen supply to the brain in hypoxic patients.

The influence of hypoxemia on tritiated digoxin plasma kinetics and tissue distribution in the conscious dog.

The goals of this study were to document the effect of hypoxemia on the distribution of digoxin in conscious dogs. For this purpose, 6 beagles were exposed to air and 6 others to an atmosphere containing 10% O2, to generate a PaO2 equal to 46.3 +/- 0.3 mmHg (mean +/- SEM). The animals received 25 micrograms/kg of digoxin containing 2.17 micrograms/kg of 3H-digoxin, and then blood and urine samples were collected over the next 48 h, at which time they were killed to determine digoxin concentrations in several tissues. Five additional beagles were used to assess the influence of hypoxemia on the blood perfusion to these tissues using radioactive microspheres. The results, expressed as digoxin equivalents, indicated that hypoxemia increased the digoxin apparent volume of distribution (2.85 +/- 0.10 versus 2.01 +/- 0.11 L/kg; p less than 0.001) and the time required to achieve this distribution (9.7 +/- 1.4 versus 2.6 +/- 0.3 h; p less than 0.01). As digoxin clearance was not influenced by hypoxemia, the half-life was increased from 25.2 +/- 1.5 to 33.4 +/- 1.3 h (p less than 0.01). With hypoxemia, digoxin concentrations increased significantly in the brain and diaphragmatic muscle, but only marginally in other organs, including the heart, the latter despite a significant increase in blood flow. It is concluded that hypoxia does change digoxin disposition but does not increase digoxin heart concentrations. Therefore, factors other than changes in digoxin plasma kinetics and heart distribution may be responsible for the decrease in digitalis tolerance during hypoxemia.