From the Guidelines
Acidosis is not a diagnosis itself, but rather a clinical condition characterized by an abnormally high acid concentration in the blood and body tissues, indicated by a blood pH below 7.35. According to the British Thoracic Society guideline for oxygen use in adults in healthcare and emergency settings, published in Thorax in 2017 1, acidosis can be caused by respiratory or metabolic disorders. The normal pH range of the blood in humans is between 7.35 and 7.45 units, and acidosis is defined as a pH<7.35 ([H+]>45 nmol/L) and alkalosis is defined as a pH>7.45 ([H+]<35 nmol/L).
Key points to consider when evaluating acidosis include:
- The underlying cause of the acidosis, which could be respiratory or metabolic in nature
- The need to identify and address the underlying disorder, rather than just treating the acidosis itself
- The importance of understanding the specific type and cause of acidosis for proper management, as treating acidosis without addressing its underlying cause would be ineffective and potentially harmful, as noted in the guideline by O’Driscoll et al. 1.
Some of the potential underlying causes of acidosis include:
- Diabetic ketoacidosis
- Lactic acidosis
- Renal failure
- Severe diarrhea
- Respiratory diseases Treatment of acidosis should focus on correcting the primary disorder, rather than just normalizing pH, as emphasized in the guideline 1.
From the Research
Definition and Diagnosis of Acidosis
- Acidosis is a condition characterized by an excess of acid in the body fluids, which can be diagnosed through a combination of clinical history, physical examination, and laboratory tests, including serum and urinary chemistries, arterial blood gases, and electrolytes 2.
- The diagnosis of metabolic acidosis can be made by calculating the anion and osmolal gaps, which can help narrow down the diagnostic possibilities 2, 3.
- Metabolic acidosis can be classified into different types, including high anion gap metabolic acidosis and hyperchloremic or normal anion gap metabolic acidosis, each with distinct causes and treatment approaches 4.
Diagnostic Criteria and Classification
- The calculation of the serum anion gap can aid in the diagnosis of metabolic acidosis, classifying the disorders into categories of normal (hyperchloremic) anion gap or elevated anion gap 5.
- The base excess and anion gap, corrected for hypoalbuminaemia and iatrogenic hyperchloraemia, are considered appropriate for clinical usage in diagnosing metabolic acidosis 3.
- Metabolic acidosis can be acute or chronic, with different underlying causes and resulting adverse effects, and can be diagnosed through a combination of clinical and laboratory evaluations 5.
Treatment and Management
- The treatment of metabolic acidosis depends on the underlying cause and can involve supportive care, therapy directed at the cause of the acidosis, and, in some cases, the use of alkalinizing agents 2, 5.
- The use of base to treat acute metabolic acidosis is controversial, while the administration of base for the treatment of chronic metabolic acidosis is associated with improved cellular function and few complications 5.
- The appropriate treatment of acute metabolic acidosis, particularly organic forms such as lactic acidosis, has been a subject of controversy, with some studies suggesting that cessation of acid production via improvement of tissue oxygenation is the most effective approach 4.