Neuroendocrine and metabolic effects of general Anaesthesia during spontaneous breathing, controlled breathing, mild Hypoxia, and mild Hypercarbia

摘要: Serial crossover tests were carried out on 10 to 15 large, trained, male dogs that moderately deeply anaesthetized for 90 minutes, at two-week intervals, with thiopental, Innovar, diethyl ether cyclopropane, chloroform, trichlorethylene, fluroxene, halothane, halothane-ether azeotrope, and methoxyflurane. These done under four conditions: spontaneous breathing 50 per cent N2O + O2 unless apnoea became imminent (chloroform-usual, cyclopropane-occasional, Innovar-briefly); controlled O2; 85 47.5 2.5 CO2. Anaesthesia was induced in all experiments 20 mg./kg. thiopental. Cyclopropane administered 70 oxygen a closed-circle system an absorber the first two conditions only. The remaining inhalation agents non-rebreathing system. Thiopental Innovar intravenously by drip infusion one hour. Blood assays of histamine, serotonin, epinephrine, norepinephrine beginning end each test along measurements pH,\(P_{aCO_2 } ,P_{aO_2 \), haematocrit, SGOT, SGPT, lactate, pyruvate, blood water, sugar, potassium, inorganic phosphorus. Volume withdrawn replaced 0.9 saline. During test, mean arterial pressure measured directly from femoral artery; rate volume monitored respirometer during or regulated 350 400 ml./kg./min. breathing; heart rhythm recorded E.C.G. (lead 2), urine excretion gravity drainage catheter attached calibrated trap bottle. All data analyzed statistically. following effects noted: 1. Thiopental usually caused rise catecholamines, but no hypotension oliguria; 2. Innovar oliguria; elevation catecholamines inconsistent; 3. Diethyl metabolic acidosis, haemoconcentration, water loss, hyperglycaemia, excess oliguria, hypotension; 4. Cyclopropane hypercapnoea (during respiration) hypotension; rose slightly; 5. Chloroform slight hyperglycaemia oliguria; 6. Trichlorethylene ollguria serotonin when CO2 administered; 7. Fluroxene elevated lactate pyruvate breathing, mild hypoxia, oliguria; 8. Halothane, methoxyflurane consistent changes. It evident most obvious disturbances, these accompanied catecholamines. There virtually appreciable changes histamine assays. Theoretically, it is possible alterations latter biogenic amines might have occurred greater extent than reported values indicate, since they released then taken up rapidly tissues receptors effector organs broken down metabolically. For matter, into anaesthesia some (the halogenated cyclopropane) may had same fate, whereas remained bloodstream. However, unlikely this occurred, if had, there been less likelihood hypotension, least more potent anaesthetics. important keep mind also considering percentage takes distorted view, particularly respect catecholamine values, because assay method involves technical errors such magnitude amount near zero, lower limit detectability (as observed many control epinephrine), difficult accept as significant those appear large experiment.