| 期刊全称 | Acid-Base Regulation and Body Temperature | | 影响因子2023 | Hermann Rahn,Omar Prakash | | 视频video | http://file.papertrans.cn/144/143936/143936.mp4 | | 学科分类 | Developments in Critical Care Medicine and Anaesthesiology | | 图书封面 |  | | 影响因子 | During the last 20 years two groups of investigators have concerned themselves with the problem of acid-base regulation at various body temperatures. Each group, in professional isolation, pursued a separate path. Surgeons and anesthe tists developed techniques and tools for hypothermic cardio-pulmonary by-pass operations and based their rationale for acid-base management on in vitro models of blood behavior. Physiologists and biochemists, on the other hand, endeavored to understand acid-base regulation in living organisms naturally subjected to changes in body temperature. Only in the last decade has there been an increasing awareness that each group could benefit from the other‘s experiences. With this goal in mind members of both groups were invited to present their views and observations in the hope of arriving at a better understanding of acid-base management during hypothermia and gaining a greater insight into the factors which control acid-base regulation during normothermia. This led to the presen tation of the present volume with the aim of providing the clinician with a survey of present theories and the resulting strategies for management of the hypother mic patient. | | Pindex | Book 1985 |
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Front Matter |
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Abstract
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| 2 |
Introduction |
H. Rahn |
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Abstract
During the last three-quarters of this century we have all been imprinted with the truism that normal blood pH is 7.4. We were never told why this particular value was important, and one accepted the fact that somehow this was ’ordained by nature.’ Nevertheless, it has served us well, in fact so well that one could easily accept the premise that our respiratory center is a pH-stat responsible for maintaining the appropriate blood reaction. It also led others to conveniently refer to a pH of 7.4 as . pH and values below or above as acidosis and alkalosis even though, since the times of Claude Bernard, we have known that normal blood is always on the alkaline side of chemical neutrality.
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What are normal acid-base conditions in man when body temperature changes? |
Robert Blake Reeves |
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Abstract
Over the short time span of 25 years the use of general body hypothermia for cardiac surgery has progressed from experimental to commonplace. In 1983 the total number of patients on whom hypothermia was employed in the United States alone exceeded 170,000. Moreover, it is now accepted that induction of and recovery from hypothermia carries minimal risks. The widespread practice of whole body hypothermia has raised the practical question of what constitutes correct acid-base management during hypothermia. This question had previously been ignored because, although principles of acid-base regulation at 37°C are well known, extension of basic theory to other body temperatures appeared of no particular utility.
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Acid-base regulation during hibernation |
A. Malan |
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Abstract
The ‘constant pH’ strategy of hibernators involves loading considerable amounts of CO. during the entrance into hibernation, and hyperventilating to eliminate this CO. during the arousal. Together with the decrease of blood alpha imidazole, this indicates that the blood pH and .observed in hibernation result from the combined effects of a respiratory acidosis and a change in temperature. The respiratory acidosis also affects most intracellular compartments of the body, except for the heart and liver, in which a metabolic compensation takes place, resulting in a nearly constant alpha imidazole. Respiratory acidosis exerts inhibitory influences on various nervous and metabolic processes, and probably contributes to the great amplitude of regulation of metabolic rate characteristic of hibernation. The inhibition would be at least partly removed early in the arousal by hyperventilation, while during deep hibernation heart and liver would be protected by the alphastat control of intracellular pH. Our ignorance of the mechanisms ensuring the selective inhibition or facilitation of pHi regulation according to tissues precludes the clinical application of the hibernation model.
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Enzymatic consequences under alphastat regulation |
George N. Somero,Fred N. White |
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Abstract
The importance of conserving the fractional protonation state of histidyl imidazole groups (alphastat pH regulation) is discussed for key structural and functional properties of proteins. For enzymes like lactate dehydrogenase (LDH) which have active site histidyl residues involved in the binding and catalytic events, the advantages of alphastat regulation are seen in the conservation of binding ability (as estimated by apparent Michaelis constants), of catalytic reserve capacity (the ability to respond effectively to changes in substrate concentration) and of reaction reversibility. For enzymes which depend on histidyl residues for their integrity of subunit assembly, e.g., phosphofructokinase (PFK), alphastat regulation ensures the maintenance of the active, assembled structure under different temperatures, and the regulatory responsiveness of the protein is also conserved. These advantages to enzymes of alphastat regulation during changes in body temperature are seen both in short-term changes in body temperature and in evolutionary adaptation to temperature..From the observed effects of changes in temperature and pH on enzyme systems studied in vitro, predictions are made about
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Acid-base management during hypothermic circulatory arrest for cardiac surgery |
Henry Swan |
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Abstract
Four fundamental strategies for acid-base management during hypothermic cardio-pulmonary by-pass (H-CPBP) are pH-stat, .-stat, alpha-stat, and respiratory alkalosis. For H-CPBP in man, the blood is diluted with saline solution to HCT 20%(ß is about 20 slykes). On the logC-T graph pH and . lines are both horizontal. This graph closely approximates the human situation.
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Hypothermia and acid-base regulation in infants |
O. Prakash,B. Jonson,S. H. Meij |
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Abstract
Hypothermia has a long history in medicine, and has been used as a remedy for diseases on the basis of its known effects and also on purely hypothetical assumptions. In ancient times, Hippocrates described the use of ice for controlling hemorrhage, a treatment that is still in frequent use. ‘Refrigeration’ was used by Baron Lary, Napoleon’s surgeon, to carry out surgical interventions on soldiers. Local cooling by evaporating ether for local anaesthesia was already in use in the middle of the last century, a principle still employed in the form of ethyl chloride spray. Total body cooling was first applied on the basis of ideas that are today regarded as non-rational, e.g., by James Currie in 1798 [1] for febrile disease, and by Talbott [2] as a form of shock therapy in psychotic patients.
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Myocardial function resulting from varying acid-base management during and following deep surface an |
Gerald D. Buckberg,Heinz Becker,Jakob Vinten-Johansen,John M. Robertson,Jerry Leaf,Douglas H. McConn |
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Abstract
This study compares the systemic and cardiac effects of three different pH strategies during surface and perfusion cooling. In six adult dogs we compared the constant pH (acid) strategy to the alkaline pH strategy during perfusion hypothermia (28°C). In 28 puppies we compared the constant α (neutral) pH strategy to the alkaline strategy during surface and perfusion hypothermia circulatory arrest for 1 hour, and subsequent rewarming. In 14 puppies (6 sufface and 8 perfusion) pH was kept at 7.4 (meter reading at 37°C) with a constant . of 35–40 mmHg to follow the constant α (neutral) pH strategy. In 14 other puppies (6 surface and 8 perfusion) pH was made progressively alkalotic by reducing . to 10 mmHg and adding buffer as necessary to simulate the most alkalotic range of ectotherms (17°C) with a pH 7.8 meter reading at 37°C. All puppies underwent 1 hour of circulatory arrest with 16° C multidose blood cardioplegia..In adult dogs, the alkaline strategy during perfusion hypothermia resulted in better total and regional left ventricular blood flow, higher LVO. uptake, better LV lactate metabolism and greater LV contratility. In puppies undergoing surface cooling, the constant α (neutr
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Back Matter |
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Abstract
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