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Biomedical subjects

E C Peirce

Publications and source records attributed to E C Peirce.

At least 37 records · Page 2Linked to original sources

Extracorporeal membrane oxygenation for massive pulmonary thromboembolism.

This study was undertaken to determine whether extracorporeal membrane oxygenation (ECMO) could modify the effects of massive lethal thromboembolism and prevent death. Twenty anesthetized dogs were prepared for venoarterial perfusion with a demand pump and membrane lung and were perfused slowly for 1 1/2 hours to lessen homologous blood shock; 1 ml per kilogram of 24-hour-old tantalum-impregnated thrombus was injected intravenously. The dogs had profound systemic hypotension with an elevated mean pulmonary artery pressure (62.9 +/-4.5 mm Hg) immediately after embolization. Control animals generally died within 15 minutes. Four of the 10 ECMO-supported animals lived for six days, at which time they were restudied and killed. Not only can ECMO maintain an animal that would otherwise die quickly of massive pulmonary thromboembolism, but such support, even though temporary, can greatly improve the chances of survival.

Animals↗

Urinary osmolal changes in renal dysfunction following open-heart operations.

Forty consecutive patients who underwent open-heart procedures using a hyperosmolar perfusion prime were studied to determine the significance of free-water clearance and urinary osmolality early after bypass in predicting the likelihood of postoperative renal dysfunction, defined as a blood urea nitrogen (BUN) level over 50 mg/100 ml. Urinary osmolality increased in all patients during the first 18 hours after bypass, but the increase was substantially less for those who subsequently developed renal dysfunction. Free-water clearance, which was significantly less negative in the patients with renal dysfunction by 2 hours after bypass and remained so throughout the 18 hours of this study, served as an early postoperative indicator of impaired renal function in the patients who eventually developed BUN elevation. Moreover, it was more sensitive as an index of renal dysfunction than was osmolality alone. Early recognition of renal impairment is important, as it may prevent dangerous fluid overloading and allow for corrective measures to be undertaken before frank renal failure develops.

Blood Pressure↗

Interactions of diphenylhydantoin and cardiac glycosides on atrial potassium.

Effects of diphenylhydantoin (DPH) on amphibian atrial myocardium K were investigated using a method which permits both total tissue K and tension response to be monitored continuously. In normal (nondigitalized) preparations, DPH caused a decrease in average K efflux, a net gain of tissue K, and negativeinotropy at low perfusate K concentrations. However, the DPH-induced gain of tissue K was abolished at high perfusate K concentrations while marked negative inotropy was still observed. It is concluded that a gain of tissue K is not the cause of DPH-induced negative inotropy. When digitalis-induced inotropy was associated with tissue K loss, DPH reversed tissue K loss and positive inotropy and caused a decrease in average K efflux. In the presence of toxic effects of digitalis, DPH reversed the K loss and the contracture, but the loss of developed tension was not reversed by DPH. Transmembrane resting potentials and action potential duration were reduced by digitalis and were returned to or above control levels in the presence of DPH. The present findings are consistent with the hypothesis that the therapeutic effect of DPH in digitalis toxicity is brought about by an inhibition of K efflux. This would tend to minimize the loss of tissue K which results from sodium pump inhibition.

Animals↗

Functional changes in platelets during extracorporeal circulation.

An in vitro trauma test was conducted to determine the effects of extracorporeal circulation on platelet count and function. Fresh human blood was circulated in two identical in vitro circuits for six hours at a rate of 500 ml per minute (500 recirculations). One circuit included a G.E.--Peirce membrane lung and the other was a control. Platelet aggregation induced by adenosine diphosphate (ADP), epinephrine, or collagen was studied before and after six hours of perfusion. No important drop in platelet count occurred in the control circuit (Control-C) following bypass, but there was a 20% drop for the lung circuit (Lung-C). Platelet aggregation was reduced by about 30% for the control circuit and 65% for the lung circuit. The large decrease in platelet function accompanied by only a moderate decrease in platelet count is discussed in terms of loss of the youngest and most active platelets, platelet inhibition due to ADP released by red blood cell lysis, and platelet trauma.

Adenosine Diphosphate↗