Acid-base disturbances

Dehydration, electrolyte imbalances, and acid-base disturbances may be evident in complex and prolonged nausea and vomiting. 

Define primary acid-base disturbances within the human body. 

Apply simple formulas in order to determine the etiology of simple acid-base disturbances and the adequacy of compensation. 

Integrate the supplemental concepts of the anion gap and the excess gap to help assess complex acid-base disturbances. 

Arterial blood gases, serum electrolytes, physical examination findings, the medical history, and the patient s recent medications must be reviewed in order to establish the etiology of a given acid-base disturbance. 

Because C02 is a volatile acid, it can rapidly be changed by the respiratory system. If a respiratory acid-base disturbance is present for minutes to hours it is considered an acute disorder while if it is present for days or longer it is considered a chronic disorder. By definition, the metabolic machinery that regulates HC03 results in slow changes in serum bicarbonate and all metabolic disorders are chronic. This means that there are six simple acid-base disorders as outlined in Table 25-1.2... 

TABLE 25-2. Diagnosis of Concurrent Acid-Base Disturbances when Compensation Is Inappropriate... 

Primary Acid-Base Disturbance Assessment of Compensation Concurrent Acid-Base Disturbance... 

HCO, that allow the user to rapidly determine whether arterial blood gas values are consistent with one of the six simple primary acid-base disturbances. Although nomograms are commonly used to identify acid-base disturbances in clinical practice, only individuals who fully comprehend the concepts of acid-base assessment should use these tools. Furthermore, nomograms have limited utility when dealing with complex acid-base derangements. 

Acid-base disturbances are always manifestations of underlying clinical disorders. It is useful to specifically define the primary acid-base abnormality, as each disorder is caused by a limited number of disease processes. Establishing the specific disease process responsible for the observed acid-base disorder is clinically important because treatment of a given acid-base disorder will only be accomplished by correcting the underlying disease process. 

Acid-base disturbances are common clinical problems that are not difficult to analyze if approached in a consistent manner. The pH, PaC02, and HCO, should be inspected to identify all abnormal values. This should lead to an assessment of which deviations represent the primary abnormality and which represent compensatory changes. The serum electrolytes should always be used to calculate the anion gap. In cases in which the anion gap is increased, the excess anion gap should be added back to the measured HC03 . The anion gap and the excess... 

Every patient with a suspected acid-base disturbance should have an arterial blood gas and a serum chemistry panel drawn concurrently. The results of these tests should be reviewed using a systematic approach to ensure proper interpretation. 

Acid-base disturbances associated with PN usually are related to the patient s underlying condition(s). However, acid-base abnormalities may develop as a result of changes in chloride or acetate concentrations in PN admixtures. Because acetate is converted to bicarbonate in the body, excessive acetate salts in PN can lead to metabolic alkalosis excessive chloride salts in PN can lead to metabolic acidosis. PN should not be used to... 

Lee E. Morrow, MD, MS Assistant Professor of Medicine Creighton University Medical Center Omaha, Nebraska Chapter 24 Fluids and Electrolytes Chapter 25 Acid-Base Disturbances... 

Chap. 25 - Acid-Base Disturbances Universal Program Number 014-999-07-039-H04... 

The therapeutic goals of diarrhea treatment are to manage the diet prevent excessive water, electrolyte, and acid-base disturbances provide symptomatic relief treat curable causes of diarrhea and manage secondary... 

General principles that are common to all types of acid-base disturbances are addressed first, followed by separate discussions of each type of acid-base disturbance. 

There are four primary types of acid-base disturbances, which can occur independently or together as a compensatory response. 

Aspirin in doses used to treal rheumatoid arthritis can result in uncoupling of oxidative phosphorylation, increased oxygen consumption, depletion of hepatic glycogen, and the pyref c effect of toxic doses of salicylate. Depending on the degree of salicylate intoxication, the symptoms can vary from tinnitus to pronounced CNS and acid-base disturbance. 

For replacing the deficit of ECF due to decreased water intake or increased secretion of water even in absence of marked acid base disturbance. 

Treatment of acid-base disturbances requires a determination of how much "acid" (NH4C1) or "alkali" (NaHCQ3) to add to the patient s system. For this... 

Figure 3.4 Identification of various acid-base disturbances. Acute disorders are synonymous with uncompensated disturbances, whereas chronic conditions are synonymous with partially compensated or compensated disturbances. If a specific case falls outside the shaded areas, a compound acid-base disturbance may be suspected, such as the coexistence of respiratory acidosis (partially compensated) and metabolic alkalosis. Unshaded areas may also indicate a transient state between an acute (uncompensated) state and a chronic (partially compensated) condition. (From Cogan MG, Rector FC Jr., Seldin DW. In Brenner BM, and Rector FC Jr, eds. The Kidney, 2nd ed., Vol. 1, Philadelphia WB Saunders, 1986, p. 860.)...

What type of acid-base disturbance is presented here ... 

Q4 How may the kidneys compensate for this patient s acid-base disturbance ... 

Initial treatment is aimed at stabilizing the acute condition, followed by identifying and correcting the underlying cause(s) of the acid-base disturbance. Additional treatment may be needed depending on the severity of symptoms and likelihood of recurrence, especially in patients with ongoing initiating events. 

Solutions correcting water, electrolyte and acid-base disturbances... 

Acid-base disturbance. Alkalosis or mixed alkalosis/ acidosis need no specific treatment. Metabolic acidosis is treated with sodium bicarbonate, which alkalinises the urine and accelerates the removal of salicylate in the urine (see p. 97). 

A woman developed a severe metabolic acidosis and coma after taking nalidixic acid 28 g (14). She was given sodium bicarbonate 600 mmol and developed a respiratory alkalosis with secondary tetany. She recovered consciousness 9 hours later and the acid-base disturbance resolved after 60 hours. 

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