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Biomedical subjects

P N Samuelson

Publications and source records attributed to P N Samuelson.

23 records · Page 2Linked to original sources
PubMed1979

Hemodynamic effects of aortic clamping and decompression with a temporary shunt for resection of the descending thoracic aorta.

To assess the effects clamping of the proximal thoracic aorta and of subsequent decompression with a temporary shunt on cardiac function during resection of aneurysms of the descending thoracic aorta, mean arterial (MAP), central venous (CVP), mean pulmonary arterial (MPAP), and pulmonary capillary wedge pressures (PCWP), as well as cardiac index (CI), were measured in eight patients at baseline, 2 minutes after clamping the aorta beyond the left carotid or left subclavian artery, and 2 minutes after opening the shunt. Following clamping, MAP, CVP, and PCWP increased significantly (P less than 0.05), while CI decreased significantly, an average of 29%, and heart rate remained unchanged. After opening the shunt, all pressures returned to baseline levels. CI increased, but remained below the baseline level in seven of the eight patients (P less than 0.05). Our data indicate that significant deterioration of left ventricular performance results from clamping and that the deleterious effects can be reversed by use of a temporary shunt. They support the recommendation of proximal aortic decompression during thoracic aneurysmectomy.

Adult↗
PubMed1976

Toxicity following methoxyflurane anaesthesia. IV. The role of obesity and the effect of low dose anaesthesia on fluoride metabolism and renal function.

Seven obese and five normal weight patients were studied before, during and after one hour of methoxyflurane-nitrous oxide anaesthesia during peripheral surgical operations and compared with eight patients of normal weight anaesthetized with nitrous oxide-meperidine and d-tubocurare. Estimates were made of renal function, including serum and urinary electrolytes, osmolarity, uric acid, urea and creatinine. Renal clearances for the latter three substances were also calculated. Serum and urinary inorganic and organic fluoride concentrations were measured, as were renal clearances. This low dose methoxyflurane anaesthesia resulted only in a decrease in uric acid clearance among all the measures, when compared to the meperidine-nitrous oxide controls. The clearance of uric acid remained depressed for longer in the obese patients, but otherwise they did not differ from the normal weight patients. It is possible but not proven that depressed uric acid clearance may be related to the organic fluoride metabolite and an early indicator of methoxyflurane renal toxicity. The previously documented biotransformation of methoxyflurane was seen in this study. A double peak in serum inorganic fluoride was shown in all patients but one. Rather large differences in peak levels of serum inorganic fluoride occurred. The only significant difference between the obese and normal weight patients as far as fluoride metabolism was concerned was a greater variability in the serum inorganic fluoride levels in the obese patients. It would appear that the obese patient metabolizes methoxyflurane in a quantitatively if not qualitatively different fashion than the normal weight patient, perhaps because of fatty infiltration of the liver. Caution is advised in the use of methoxyflurane for more than 90 minutes of low concentration administration in view of the unpredictability of the biotransformation.

Anesthesia↗