Annals of clinical research
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The most important determinants of the overall O2 delivery to tissues are the cardiac output and the arteriovenous O2 content difference. The latter is influenced mainly by the haemoglobin concentration, arterial haemoglobin O2 saturation and venous haemoglobin O2 saturation. Also the O2 tension has a minor contribution. ⋯ This effect allows greater O2 extraction from the blood by tissues. The changes in the haemoglobin O2 affinity are compensated in physiological conditions by changes in the cardiac output and in the venous O2 tension. If, however, in a situation of limited tissue O2 supply these mechanisms are used up or severely compromised the haemoglobin O2 affinity becomes an important determinant of the O2 delivery to tissues.
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The present experiments compare the relative effectiveness of several plasma substitutes to reverse a standardized intestinal ischemic shock in dogs and rats. The colloids were given 3.5% solutions in a dose of 1.5 g/kg = 43 ml/kg for dogs and 2 g/kg = 57 ml/kg for rats.. Ringer's solution was given in a three times larger volume. ⋯ Colloids of 3.5 and 6% were more effective than a 10% colloid solution. These effects were related to the molecular weight distribution for colloids, the plasma volume expansion duration and their red blood cell aggregation properties. It is concluded that as single infusions albumin, dextran 40, and dextran 70 are superior to ACD plasma, gelatin, and Ringer's acetate in restoring hemodynamic and metabolic functions and in improving survival rate.
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Seventy-nine patients suffering from severe bronchial asthma were treated in the intensive care unit (ICU) between 1970 and 1978. This was 0.8% of the total number of asthmatic patients treated in Meilahti hospital during the same period. ⋯ In 65% tracheal intubation and mechanical ventilation were needed besides the conventional treatment. In spite of intensive care 9% of the patients died.
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Clinical Trial Controlled Clinical Trial
Plasma lidocaine concentrations after different methods of releasing the tourniquet during intravenous regional anaesthesia.
Different methods of tourniquet release have been proposed to decrease the concentrations of local anaesthetic released into the systemic circulation at the end of intravenous regional anaesthesia. The effect of releasing the tourniquet intermittently with 5 seconds (group I) and 30 seconds (group II) deflation periods or at once (group III) was studied in 25 adult patients after intravenous regional anaesthesia with 40 ml of 0.5% lidocaine. The venous plasma lidocaine concentrations from the contralateral arm were measured by gas chromatography. ⋯ There were subjective complaints such as dizziness and ringing in the ears in 4 out of the 7 patients in group I, in 2 out of the 9 patients in group II and in one of the 9 patients in group III (P greater than 0.05). There was no correlation between the duration of tourniquet time (range 12-87 minutes) and the maximum plasma lidocaine concentration. The intermittent release of the tourniquet did not decrease the venous plasma lidocaine concentrations in the contralateral arm; neither did comparing the lidocaine pharmacokinetics in 5 patients of group II after tourniquet release and in the 5 healthy volunteers after a single 100 mg intravenous lidocaine injection reveal any differences.
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Twenty one patients with either paroxysmal supraventricular tachycardia (group A), atrial flutter (group B), or atrial fibrillation (group C) were treated with intravenous metoprolol in the dose range 2--20 mg. Sinus rhythm was restored in 3 out of 6 patients in group A, 3 out of 7 patients in group B and one out of 8 patients in group C. ⋯ In patients with systolic blood pressure greater than 100 mm Hg but without an acute myocardial infarction the risk of hypotension necessitating treatment was small. Metoprolol appears to be an effective and safe drug in the treatment of supraventricular tachycardia.