Understand the clinical approach to acid base disorders, including the basic equation, questions to ask about each disorder, the use of venous electrolytes, arterial blood gases, and the acid base. A stepwise systematic approach can be used to determine the etiology and proper management of acid base disorders. Understand the mechanisms for regulating acidbase physiology. Introduction history the last century has proven to be a turning point in mankinds understanding of acid base chemistry and its role in emergency medicine. Acid base balance is maintained by effective renal and respiratory homeostatic mechanisms fig 2. Acidbase disorders msd manual professional edition.
Lung function, transport of co 2 and acidbase balance a constant amount of co 2 in blood, essential for normal acidbase balance, reflects a balance between that produced as a result of tissue cell metabolism and that excreted by the lungs in expired air. Acid base, boy bands, and grandfather clocks with joel. Bicarbonate is the agent of choice for the treatment of acute metabolic acidosis. Recent advances in the understanding of acidbase physiology have resulted from the application of basic physicalchemical principles of aqueous solutions to blood plasma. Objectives define normal ranges of electrolytes comparecontrast intracellular, extracellular, and intravascular volumes outline methods of determining fluid and acidbase balance describe the clinical manifestations of various electrolyte imbalances. The ph buffer systems work chemically to minimize changes in the ph of a solution by adjusting the proportion of acid and base.
Acid base balance normal ph range of ecf is from 7. Deviations of systemic acidity in either direction can impose adverse consequences and when severe can threaten life itself. After completing this article, readers should be able to. Acid base balance arterial blood gases acidosis alkalosis. Sep 01, 2016 the bodys ability to maintain acidbase homeostasis is based on a complex set of interactions between the respiratory and metabolic systems. Acidbase imbalance an overview sciencedirect topics. Learning objectives the clinician after participating in the roundtable will be able to. Level of acidic compounds in the body rises through increased intake or production, or decreased elimination level of basic alkaline compounds in the body falls.
The pco2 varies directly with ventilation, and is the primary abnormality in the respiratory acid base disorders. There are many disordersdiseases that lead to changes in acid base balance. Volatile acid co2 and nonvolatile acids, lactate, h2po4, h 2co3 2. Primary disorder alkalemia metabolic alkalosis high hco 3 respiratory alkalosis low pco 2 acidemia metabolic acidosis low hco 3 respiratory acidosis high pco 2 ph pco 2 hco 3 7. Disorders of acidbase involve the complex interplay of many organ systems including brain, lungs. Accurately interpreting acid base balance requires simultaneous mea surements of arterial ph and plasma. The revision of the book would not have been possible without the help of many. Analysis of the arterial blood gave the following values. Like its highly acclaimed predecessors, the fifth edition of this classic effectively integrates the essentials of renal and electrolyte physiology with the common clinical disorders of acidbase and electrolyte balance.
There are many disorders diseases that lead to changes in acid base balance. Kim is a 38yearold women admitted to the hospital for bulimia. Acid base disorders frequently are encountered in the outpatient and especially in the inpatient setting. These conditions are not rare or uncommon in clinical practice, but everyday occurrences on the ward or in critical care. From springer core concepts in the disorders of fluid, electrolytes and acid base balance from springer fluid, electrolyte, and acid base disorders are central to the daytoday practice of almost all areas of patientcentered medicine both medical and surgical.
Treatment is dependent on correctly identifying the acidbase disorder and, whenever possible, repairing the underlying causal process. Disorders of acidbase balance are classified according to their cause, and the direction of the ph change, into respiratory acidosis, metabolic acidosis, respiratory alkalosis, or metabolic alkalosis. Electrolyte concentrations in the ecf and the icf electrolyte extracellular fluid meql intracellular fluid meql plasma interstitial muscle sodium 140 145 12 potassium 4. Fluids, electrolytes, acidbase disorders, and nutrition. A doctor evaluates a persons acidbase balance by measuring the ph and levels of carbon dioxide an acid and bicarbonate a base in the blood. Understanding acidbase balance ceconnection for allied health. These weak acids and bases exist in pairs that are in balance under normal ph conditions.
In addition, boardtype questions with explanations are provided for each clinical disorder to increase the knowledge of the physician. Lung function, transport of co 2 and acid base balance a constant amount of co 2 in blood, essential for normal acid base balance, reflects a balance between that produced as a result of tissue cell metabolism and that excreted by the lungs in expired air. Diagnosis is made by arterial blood gas interpretation. Fluid, electrolyte, and acid base disorders, vol 1. In particular kydd, oard, and peters 1 appear to object to. Disorders of acidbase balance m aintenance of acid base homeostasis is a vital function of the living organism. Bhagavan, chungeun ha, in essentials of medical biochemistry second edition, 2015. Billie lou wood professor of pediatrics, associate chairman for clinical affairs. Acid base balance whenever blood ph changes, the body attempts to maintain this via the lungs and the kidneys. Tests for the acidbase balance status wikilectures.
The major causes of simple and mixed disturbances shoud be kept in mind so that such disorders may be predicted from the patients clinical picture. In practice, acidbase disorders can be approached very systematically as they can be. Director, section of pediatric pulmonology, critical care and allergy, james whitcomb riley hospital for children, indianapolis, in. The hco3 concentration is regulated by the kidney, and is the primary abnormality in the metabolic acidbase disturbances discussed below. A stepwise systematic approach can be used to determine the etiology and proper management of acidbase disorders. Fluids, electrolytes, acidbase disorders, and nutrition support. In practice, acidbase disorders can be approached very systematically as they can be easily diagnosed when certain rules are applied. Normal arterial blood ph is restricted to a very narrow range of 7.
Your kidneys and lungs work to maintain the acidbase balance. Propose the mechanism by which asthma contributed to the lab results seen. Diagnosing acidbase disorders ak ghosh abstract diagnosis and management of acidbase disorders ranks high among the medical problems that intimidate many physicians. Acidbase balancephysiologic compensationselectrolyte disorders. The bodys ability to maintain acidbase homeostasis is based on a complex set of interactions between the respiratory and metabolic systems.
Acidbase homeostasis is fundamental for maintaining life. Thus, the respiratory contribution to acid base balance is usually discussed in terms of co 2 rather than of carbonic acid. Acidbase balance whenever blood ph changes, the body attempts to maintain this via the lungs and the kidneys. Acutechronic phase only with respiratory disorders. Classify his acidbase balance as acidosis or alkalosis, and as metabolic or respiratory. Cases for each fluid, electrolyte, and acid base disorder are discussed with answers. Acidbase disorders frequently are encountered in the outpatient and especially in the inpatient setting.
Acidbase disorders made so easy even a caveman can do it lorraine r franzi, mshsm, rd, ldn, cnsd nutrition support specialist university of pittsburgh medical center pittsburgh, pa i. In these mixed disorders, values may be deceptively normal. The mechanism which overcomes this problem and serves to maintain normal blood ph i. The 3 key questions to ask about any acid base disorder are. If you continue browsing the site, you agree to the use of cookies on this website. Virtually every aspect of these disorders has experienced. Thus, the respiratory contribution to acidbase balance is usually discussed in terms of co 2 rather than of carbonic acid.
Acidbase balance and the anion gap bloomington campus. Core concepts in the disorders of fluid, electrolytes and. Additionally, fulop et al noted the complexity of the acidbase disorders because half of their patients were not acidemic and. A doctor evaluates a persons acid base balance by measuring the ph and levels of carbon dioxide an acid and bicarbonate a base in the blood. These conditions can be categorized as acidoses or alkaloses and have a respiratory or metabolic origin, depending on the cause of the imbalance. As discussed earlier in this chapter, the concentration of carbonic acid in the blood is dependent on the level of co 2 in the body and the amount of co 2 gas exhaled through the lungs. In fact wrenn et al showed that only 55% of the patients are acidemic and 78% had a mixed acidbase disorder 4. Blood ph is described by the hendersonhasselbalch equation 3. Clinical physiology of acidbase and electrolyte disorders. Jun 18, 2018 your bodys ph balance, also referred to as its acidbase balance, is the level of acids and bases in your blood at which your body functions best the human body is built to naturally maintain. The bloods acidbase balance is precisely controlled because even a minor deviation from the normal range can severely affect many organs. An introduction to acidbase balance in health and disease. Disorders of potassium andacidbase balance alexander c.
Your kidneys and lungs work to maintain the acid base balance. Easy way to understand stewarts acidbase vi preface understanding the chemistry of water and hydrogen ions is an important part of understanding the living system because hydrogen ions participate in so many reactions. Disorders of acid base balance m aintenance of acid base homeostasis is a vital function of the living organism. The body uses different mechanisms to control the bloods acidbase balance. Disorders of acid base balance an overview sciencedirect. Pdf 92 acidbase balance and disorders monica hernandez. Understanding acidbase disorders queens university belfast. Blood be was introduced to replace plasma hco 3 with a measure of the metabolic component that is independent from the respiratory component. Understanding acidbase disorders ulster medical society. The ph buffer systems are combinations of the bodys own naturally occurring weak acids and weak bases.
Like its highly acclaimed predecessors, the fifth edition of this classic effectively integrates the essentials of renal and electrolyte physiology with the common clinical disorders of acid base and electrolyte balance. Metabolic acidosis and metabolic alkalosis objectives by the end of this chapter, you should be able to. The core of information that the clinician should possess from the preface. Disorders of acidbase balance anatomy and physiology ii. The hco3 concentration is regulated by the kidney, and is the primary abnormality in the metabolic acid base disturbances discussed below. Thus, it is important when evaluating acidbase disorders to determine whether changes in p co 2 and hco 3. Acidbase disorders knowledge for medical students and. Additionally, fulop et al noted the complexity of the acid base disorders because half of their patients were not acidemic and. Acidbase imbalance is an abnormality of the human bodys normal balance of acids and bases that causes the plasma ph to deviate out of the normal range 7. The bloods acid base balance is precisely controlled because even a minor deviation from the normal range can severely affect many organs. Your blood needs the right balance of acidic and basic alkaline compounds to function properly. Disorders of acidbase balance m aintenance of acidbase homeostasis is a vital function of the living organism. In fact wrenn et al showed that only 55% of the patients are acidemic and 78% had a mixed acid base disorder 4. Acidbase disorders are broadly classified into problems involving metabolic andor respiratory.
Master the 5 steps for interpreting acidbase disorders and decode any abg, vbg, and bmp to find the primary disorder, and any other disorders tucked away in the abg. Disorders of acidbase balance anatomy and physiology. All changes in blood ph, in health and in disease, occur through changes in three variables. Acidbase balance is maintained by effective renal and respiratory homeostatic mechanisms fig 2. Background intensivists spend much of their time managing problems related to fluids, electrolytes, and blood ph. Changes in paco 2 level and bicarbonate concentration hco 3 can help identify the nature of the acidbase disorder. Overview of acidbase balance hormonal and metabolic. Classify his acid base balance as acidosis or alkalosis, and as metabolic or respiratory. Inonesuchanalysisof cancerrelated admissions, 47% of patients with mostly solid tumors had hyponatremia, and of these, 11% had moderate sodium na 120129 meql to severe na, 120 meql hyponatremia 1. Your bodys ph balance, also referred to as its acidbase balance, is the level of acids and bases in your blood at which your body functions best the human body is built to naturally maintain. Acid base disorders made so easy even a caveman can do it lorraine r franzi, mshsm, rd, ldn, cnsd nutrition support specialist university of pittsburgh medical center pittsburgh, pa i.
The body uses different mechanisms to control the bloods acid base balance. Remember that a molecule of carbonic acid is lost for every molecule of co 2 exhaled, and a molecule of carbonic acid is formed for every molecule of co 2 retained. Table 1 definitions and main causes of acid base disorders. Changes in paco 2 level and bicarbonate concentration hco 3 can help identify the nature of the acid base disorder. In the fetus, the normal range differs based on which umbilical vessel is sampled umbilical vein ph is normally 7. Table 1 definitions and main causes of acidbase disorders. Acidbase derangements are encountered frequently in clinical practice and many have lifethreatening implications. Identify the physiology involved in acidbase balance and correction. Complex or mixed acidbase disturbances involve more than one primary process.
681 87 1635 534 802 848 718 765 1546 958 1567 1598 83 255 1094 1188 1113 1274 702 503 1029 1534 1169 1259 420 163 367 173 570 1249 894 418 948 715 1120 351 145 813 761 367 1100