Mixed acid-base disorders

The excess gap represents the amount of HC03 that has been lost due to buffering unmeasured cations. The excess gap can be added back to the measured HC03 to determine what the patient s bicarbonate would be if these endogenous acids were not present. This is a very valuable tool that can be used in narrowing the differential diagnosis of certain acid-base disorders as well as in uncovering occult or mixed acid-base disorders. 

Mixed acid-base disorder More than one of the following disorders occurring simultaneously acidosis (metabolic or respiratory) and alkalosis (metabolic or respiratory). 

Failure of compensation is responsible for mixed acid-base disorders such as respiratory acidosis and metabolic acidosis, or respiratory alkalosis and metabolic alkalosis. In contrast, excess compensation is responsible for metabolic acidosis and respiratory alkalosis, or metabolic alkalosis and respiratory acidosis. 

The most common mixed acid-base disorder is respiratory and metabolic alkalosis, which occurs in critically ill surgical patients with respiratory alkalosis caused by mechanical ventilation, hypoxia, sepsis, hypotension,... 

The combination of respiratory and metabolic alkalosis is the most common mixed acid-base disorder. This mixed disorder occurs frequently in critically ill surgical patients with respiratory alkalosis caused by mechanical ventilation, hypoxia, sepsis, hypotension, neurologic damage, pain, or drugs, and with metabolic alkalosis caused by vomiting or nasogastric suctioning and massive blood transfusions. It may also occur in patients with hepatic cirrhosis who hyperventilate, receive diuretics, or vomit, as well as in patients with chronic respiratory acidosis and an elevated plasma bicarbonate concentration... 

Kaehny WD. Pafiiogenesis and management of respiratory and mixed acid-base disorders. In Schrier RW, ed. Renal and Electrolyte Disorders, 5th ed. Philadelphia, Lippincott, Williams Wilkins, 1997 172—191. 

Narins RG, Emmett M. Simple and mixed acid-base disorders A practical approach. Medicine (Baltimore) 1980 59 161-187. 

Other examples of mixed acid-base disorders commonly encountered are ... 

The interpretation of mixed acid-base disorders may be confusing if one of the disorders mimics the expected compensation. Knowledge of the clinical picture is important if the correct interpretation is to be placed on the results. 

What is the evidence that this patient has a mixed acid-base disorder Identify the components. 

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