Assessment in acid base imbalances includes level of consciousness, respiratory efforts, lung sounds, and vital signs. Level of consciousness is often altered and can present with anxiety and restlessness or a stuporous condition.

Respirations will increase in metabolic acidosis and decrease in metabolic alkalosis as compensation is attempted. Conditions such as pneumonia or COPD lead to respiratory acidosis. Lungs sounds may include crackles, rhonchi, or diminished breath sounds.

Tachycardia is expected in hypoxia except when it is profound, and then bradycardia will result. Changes in blood pressure will also occur. Hypotension is seen in acidosis. Hypertension in alkalosis.

Interventions focus on identification and treatment of the cause of the imbalance(s). In critical situations, such as an acidotic state with hypoxia, it is important to maximize oxygenation with intubation.​

Potassium is an intracellular ion. When the level of hydrogen ions increase in metabolic acidosis the body will try to maintain homeostasis by shifting some of the hydrogen intracellularly. Since potassium and hydrogen exchange for one another, in acidosis, hyperkalemia is expected. If normokalemia or hypokalemia is present, it indicates a significant depletion of potassium stores in the body and supplemental potassium must be administered. As acidosis is corrected, hydrogen shifts out of the cell and potassium shifts back in.  

With interpretation, the imbalance may be uncompensated, compensated, or partially compensated. To simplify this, when it is uncompensated, the pH is abnormal. When it is compensated, the pH is normal but there are other abnormal values.

R-O-M-E may be used for interpretation and is frequently taught in nursing programs.​

Respiratory acidosis is caused by an increase in CO2. It is seen in pneumonia, pulmonary edema, CNS depression, COPD, or pain with breathing leading to hypoventilation. Management includes oxygen, increasing ventilation, increasing perfusion, and increasing diffusion of gases.

Respiratory alkalosis is caused by a decrease in CO2. It is seen in hyperventilation and is usually an acute event. Management includes oxygen, sedation, breathing into a paper bag, and adjusting ventilator settings.

Metabolic acidosis is caused by an increase in hydrogen or a decrease in bicarbonate. It is seen in sepsis, DKA, renal or liver failure, shock, diarrhea, or malabsorption. Management includes treating the problem. Sodium bicarbonate is given in select conditions.

Metabolic alkalosis is caused by a decrease in hydrogen or an increase in bicarbonate. It is caused by vomiting, gastric suctioning, multiple transfusions, or use of antacids. Management includes treating the problem.

“Memory Hints” reflect assessment, interventions, the role of potassium, interpretation, and causes.

• There are 4 acid-base imbalances. Venous pH is 0.04 less than arterial.
• Blood pressure follows the pH. ↓ BP in acidosis. ↑ BP in alkalosis.
• When the patient is acidotic and hypoxic, the priority is to intubate.
• K+ and H+ exchange for one another.
• In acidosis, they need to be hyperkalemic.
• If the pH and Bicarbonate are Both in the same direction, then it is a metabolic problem.
• Vomit acid and poop base. ↑ pH in vomiting; ↓ pH in diarrhea.​

In preparing for the NCLEX exam, the key to acid base interpretation is to keep it simple. Using some of these “Memory Hints” will help to correlate the interrelationships that exist, clinical manifestations, and treatment.

In looking at the clinical scenario, determine if the imbalance is compensated or uncompensated, and then determine if it is acidosis or alkalosis. Look at oxygenation. If hypoxia and acidosis are both present, the key is to intubate. Look at the potassium level and if it is normal or low, the treatment is to give supplements intravenously since it is a critical situation.