Protocole d''anesthésie du porc. Effets de la saignée sur la circulation et l''équilibre acido-basique

Haemodynamic parameters and their variations after the loss of 250 and 500 ml of blood under anaesthesia were studied in nine, 11 to 12 week-old, domestic swine weighing 37.4 +/- 2.6 kg. Premedication consisted of 2 ml azaperone i.m. Anaesthesia was induced with thiopentone, followed by suxamethonium to allow the easy placement of a cuffed endotracheal tube. Anaesthesia was maintained with phenoperidine and pancuronium. The animals were mechanically ventilated with a 50/50 nitrous oxide-oxygen mixture. A catheter was inserted in each of the femoral artery, upper hepatic vein, vena cava and portal vein. Right atrial, pulmonary and wedge pressures were measured; stroke volume, systemic and pulmonary resistances were calculated (fC 90 c X min-1, Pa 82 mmHg, Pra 4.7 mmHg, Ppa 24 mmHg, Ppw 11.6 mmHg, Q 4.45 l X min-1 and Rsa 1460 dyn X s X cm-5). The swine were then bled. After a bleed of 250 ml (t1), the haemodynamic parameters were significantly modified. After another bleed of 250 ml (t2), the heart rate only was significantly higher than at t1; but the blood transfusing could not re-establish a normal haemodynamic state. Blood samples were obtained to measure pH and total CO2 in a systemic artery, and the upper hepatic veins, vena cava and portal vein: the results suggested that the liver took part in the removal of acid metabolites.     

Efficacité respective du Cell Saver ® et de la récupération du circuit de CEC ultrafiltré en chirurgie cardiaque

The efficiency of two intraoperative techniques of blood saving were compared prospectively. During a period of eight months, in 120 adults patients undergoing heart surgery with a cardiopulmonary bypass (CPB). They all had blood removed before the start of CPB for isovolaemic haemodilution. They were randomly assigned to two groups (n = 60 for each): for group A patients, blood was salvaged during surgery before the start of the CPB, during cardioplegia, and from the CPB circuit at the end of surgery, using a Cell Saver 1V (Haemonetics), and returned to the patient in theatre or in intensive care; in group B patients, blood in the CPB circuit at the end of surgery was ultrafiltered and returned to the patient at the same time as 0.8 mg.kg-1 protamine sulfate. The same anaesthetic protocol was used in all the patients (flunitrazepam, phenoperidine and pancuronium bromide). There was no significant difference between the two groups in the volume of blood removed at the start of surgery (9.12 +/- 2.01 ml.kg-1 (A) vs. 8.85.2.22 ml.kg-1 (B)), in the amounts of replacement fluid (Haemaccel, 4% albumin) given to maintain volaemia, and in postoperative blood loss Red cell count, haemoglobin level and haematocrit were higher in the Cell Saver group at the third postoperative hour and on the first postoperative day, whereas fibrinogen levels and platelet count were higher in the ultrafiltration group at the same times. A mean of 1.02 +/- 1.71 homologous blood units were given to group A and 1.45 +/- 1.71 in group B (not significant).(ABSTRACT TRUNCATED AT 250 WORDS)     

Effets de la pression expiratoire positive sur les débits cardiaque et hépatique plasmatique estimé au cours de la ventilation contrôlée chez l''homme

This study aimed to discover the effects of artificial ventilation with positive end-expiratory pressure (PEEP) on cardiac output and hepatic blood flow in ten patients with chronic stable post-anoxic or post-traumatic coma, without any cerebral oedema or any other visceral pathology. This study was carried out at four levels of end-expiratory pressure (0, 5, 12 and 29 cmH2O) and after 24 h of artificial ventilation with a PEEP arbitrarily fixed at 12 cmH2O. Cardiac output was measured by thermodilution and hepatic blood flow by applying Fick's principle on a continuous infusion of indocyanine green with an analysis of suprahepatic venous samples. Hepatic blood flow is given by the amount of indocyanine green infused (0.5 mg.min-1) divided by the difference between arterial and suprahepatic venous indocyanine green concentration. For all levels of PEEP, mean arterial, right atrial, wedge and suprahepatic pressures and hepatosplanchnic resistances were measured. Artificial ventilation with PEEP induced a fall of cardiac output and hepatic blood flow proportional with the increase in PEEP level. The fall in hepatic blood flow began to be statistically significant for a PEEP level of 5 cmH2O (-17%; p less than 0.01) and was maximum for a PEEP of 20 cmH2O (-49.51%; p less than 0.001). There was no linear correlation between cardiac output and hepatic blood flow: the fall in hepatic blood flow was more important than the fall in cardiac output. These changes in hepatic blood flow were accompanied by a significant increase in hepatosplanchnic resistances (p less than 0.01 for PEEP = 12 cmH2O), without any changes in other haemodynamic parameters or biological signs of hepatic disturbance.(ABSTRACT TRUNCATED AT 250 WORDS)     

Choc anaphylactique au cours de la grossesse à terme. À propos de deux cas et revue de la littérature

Anaphylaxis is a relative uncommon event in pregnancy that can have serious implications for both mother and foetus. Two cases of grade 3 anaphylactic shock occurring at the end of the third trimester of pregnancy are reported; the causal agents were respectively amoxicilline and suxamethonium. Maternal and foetal outcome was good after adequate resuscitation and caesarean section performed in both cases because of severe bradycardia. A review of the literature confirms the good maternel outcome; neurologic damage in the newborn is frequent. On the basis of physiologic findings degranulation of placental mast cell is evoked in the genesis of birth asphyxia.     

Effets de la lidocaïne sur la circulation artérielle et veineuse des membres chez l'homme

The effects of intravenous lidocaine on limb arteries and veins were investigated in a placebo-controlled study. Seven young healthy volunteers, 23 to 28 — years — old, were included. Electrocardiogram, arterial pressure and arm and leg blood flows were recorded continuously. Systolic and diastolic blood pressures were measured in the left arm by finger photoplethysmography. Limb blood flow and the limb venous system were studied by venous occlusive plethysmography. The venous parameters studied were venous tone, lowest closing pressure, venous volume at 30 mmHg, and venous distensibility. After an initial bolus of 1.5 mg · kg⁻¹ lidocaine had been given, 30, and then 60, μg · kg⁻¹ · min⁻¹ were given for one hour each. Plasma noradrenaline and serum lidocaine titres were measured before giving the lidocaine, and at the end of each one hour period. Placebo consisted in a two hour infusion of 0.25 ml · min⁻¹ normal saline. Lidocaine titres were 1.64 ± 0.40 μg · ml⁻¹ after one hour, and 2.55 ± 0.69 μg · ml⁻¹ after two hours. Lidocaine increased vascular resistances in both the forearm (+ 81 % to + 93 %) and the calf (+ 38 % to + 57 %). There was a concomitant increase in mean arterial blood pressure (+ 21 % to + 28 %) without any change in heart rate. There was a significant dose-dependent increase in plasma noradrenaline levels during the second period of the lidocaine infusion with respect to the preinfusion period and the same period during the placebo infusion. Venous capacitance measured before any infusion had been started was greater in the leg than in the arm. Lidocaine induced a progressive increase in forearm venous tone, which became significant during the period of higher infusion rate. There wasn't any change in calf venous tone. It would therefore seem that the arterial and venous effects of lidocaine which have been reported may be due to an increase in adrenergic tone. The vascular effects of therapeutic serum levels of lidocaine may contribute to the good cardiovascular tolerance of this drug, both as local anaesthetic agent, and as antiarrhythmic drug.     

Dépistage de l'hyperthermie maligne anesthésique par les tests de contracture musculaire et par la spectroscopie RMN

To diagnose malignant hyperthermia susceptibility (MHS), caffeine and halothane contracture tests were performed on six patients. One of them, who presented a peroperative crisis, was recognized as MHS; the five others were negative (MHN). By means of ³¹P-NMR spectroscopy, the muscular energetic metabolism of these patients was studied during and after moderate exercise in normal and moderate ischaemic conditions. Metabolic abnormalities appeared in the MHS patient. It must be concluded therefore that malignant hyperthermia is a latent myopathy. ³¹P-NMR spectroscopy appeared to be a useful non-invasive tool for screening for this affliction.     

Association nitroglycérine et remplissage vasculaire dans la chirurgie de l''aorte abdominale

Haemodynamic investigations were performed in nine patients during aortic surgery for Leriche's syndrome. Most of these patients had ischaemic heart disease without cardiac failure. Fluid loading was carried out before and during aortic clamping. It was controlled according to the optimal wedge pulmonary pressure determined the day before surgery. Only six of the nine patients receive nitroglycerin (NTG : 0.2 micrograms X kg-1 X min-1) throughout the operation. Before clamping, cardiac index was improved in patients treated with NTG. During clamping, the patients not treated with NTG showed a drop in cardiac index, an increase in peripheral resistance and in left cardiac work. After declamping, there were no haemodynamic differences between the two groups. Two patients not treated with NTG developed azotaemia postoperatively; one patient developed cardiac failure requiring a dopamine perfusion during surgery. In this series, the association of optimal volume loading with a peroperative perfusion of 0.2 micrograms X kg-1 X min-1 NTG gave a good haemodynamic stability.