Assessment of acid base imbalance

When evaluating the laboratory results of a patient with diabetic ketoacidosis, which lab value indicates the body has fully compensated from this acid-base imbalance?

Arterial blood gas pH returns to normal when the body's compensatory efforts are fully effective. Glucose, potassium, and bicarbonate are affected by diabetic acidosis, but their return to normal is not an indicator of acid-base balance. p190

Which organs play major roles in maintaining pH balance in the body?

Blood pH represents a delicate balance between hydrogen ions (acid) and bicarbonate anions (base), which is largely controlled by the lungs and kidneys. The lungs adjust the blood pH by releasing or retaining hydrogen ions (acid), and the kidneys adjust the blood pH by releasing or retaining bicarbonate anions (base). The liver plays a role in metabolism, immunity, and clotting. The pancreas releases insulin for glucose metabolism and enzymes for digestion. The brain plays a secondary role in maintaining pH balance by sensing the need for alterations in acid or base levels and sends appropriate signals to the kidneys and lungs. p187

What is one of the causes of acidosis?

Causes of acidosis include kidney failure, pancreatitis, liver failure, and dehydration. Excessive body fluids, heart failure, and colitis are causes of alkalosis. p191

Which conditions can cause metabolic acidosis? Select all that apply.

Diarrhea, liver failure, and kidney failure can result in metabolic acidosis. Airway obstruction and respiratory depression may result in respiratory acidosis.p187

When caring for a patient with metabolic acidosis, what must the nurse keep in mind regarding acid-base chemistry?

Fluids with lower pH have a higher level of free hydrogen ions and therefore have higher acidity. Acids release hydrogen ions rather than bind with them when dissolved in water. Strong acids readily dissociate in water and release all of their hydrogen ions. Acetic acid (CH 3COOH) is a weak acid. When dissolved in water, it releases only one of its four hydrogen molecules. Normally, blood has a pH of between 7.35 and 7.45, so it is slightly alkaline. p185

What is one of the causes of respiratory alkalosis?

Hyperventilation is one cause of respiratory alkalosis, which can result from fear and anxiety. Kidney failure and diuretic therapy are not causes of respiratory alkalosis. The use of antacids can result in metabolic alkalosis. 196

A patient has been poisoned by botulinum toxins. What assessment findings suggest the patient has acidosis? Select all that apply.

If the patient is confused and has a warm, flushed, and dry skin, it may indicate the patient has acidosis. Acidosis decreases the ability of excitable tissues in the blood vessels to respond adequately. So, there is vasodilation leading to hypotension rather than hypertension. Decrease in the ability of the excitable tissues in the muscles to respond adequately to stimulus and the hyperkalemia associated with acidosis reduce the muscle tone. This leads to hyporeflexia rather than hyperreflexia. Mild acidosis may increase the heart rate, but as the acidosis worsens and there is hyperkalemia, the heart rate decreases making the peripheral pulse hard to find. Therefore the peripheral pulse is thready rather than pounding. p193

A patient admitted with diabetic ketoacidosis was treated for metabolic acidosis with intravenous (IV) fluids and insulin. Which electrolyte imbalance does the nurse monitor for as the acid-base imbalance resolves?

In acidosis, extracellular hydrogen ions move into the cell and potassium moves out, causing hyperkalemia. In diabetic ketoacidosis, by treating the elevated serum glucose with insulin and IV fluids, the acid-base imbalance resolves. As the acidosis resolves, the hydrogen ions move out of the cell, and potassium moves back into the cell, causing hypokalemia in the plasma. Sodium levels are not affected by diabetic ketoacidosis. p196

A diabetic patient shows symptoms of diabetic ketoacidosis. What mechanism causes acidosis in this patient?

In diabetic ketoacidosis, there is an excessive breakdown of fatty acids. This produces strong acids (ketoacids) with the release of large amounts of hydrogen ions. Underelimination of hydrogen ions occurs when hydrogen ions are produced at normal rates, but their elimination is reduced. This is seen in patients with lung and kidney problems. Bicarbonate ion is made in the kidney or in the pancreas. In patients with impaired kidney or pancreatic function, there is underproduction of bicarbonate ions leading to acidosis. Overelimination of bicarbonate ions occurs when there is an excessive loss of bicarbonate ions. This occurs in diarrhea.

When caring for a patient with kidney failure who has metabolic acidosis, which symptom does the nurse expect as evidence of the body's compensatory effort?

Kussmaul respirations (rapid, deep respirations) represent the body's attempt to compensate for metabolic acidosis. The skin is warm, dry, and flushed in metabolic acidosis. Cardiovascular symptoms may occur, but they are manifestations of acidosis, not evidence of compensation. p193

To decrease the risk of acid-base imbalance, what goal must the patient with diabetes mellitus strive for?

Maintaining blood glucose levels within normal limits is the best way to decrease the risk of acid-base imbalance. Blood glucose levels must be checked not once but several times a day. Drinking 3 L of fluid per day is not necessary to maintain acid-base balance. Eating regularly is a way to achieve acid-base balance but is not the goal itself.

A patient is admitted with severe diabetic ketoacidosis. Arterial blood gas results reveal a pH of 7.21. What is this patient's acidosis most likely in response to?

Metabolic acidosis can result from the overproduction of hydrogen ions, underelimination of hydrogen ions, or insufficient bicarbonate ions. Excessive breakdown of fatty acids that occurs with diabetic ketoacidosis or starvation results in overproduction of hydrogen ions and metabolic acidosis. Anaerobic metabolism produces lactic acid as a cause of metabolic acidosis. Excessive intake of alcoholic beverages will also cause metabolic acidosis because of the high concentration of hydrogen ions in alcohol. Excessive intake of insulin will not result in diabetic ketoacidosis.

A patient is admitted with severe diabetic ketoacidosis. Arterial blood gas results reveal a pH of 7.21. What is this patient's acidosis most likely in response to?

Metabolic acidosis can result from the overproduction of hydrogen ions, underelimination of hydrogen ions, or insufficient bicarbonate ions. Excessive breakdown of fatty acids that occurs with diabetic ketoacidosis or starvation results in overproduction of hydrogen ions and metabolic acidosis. Anaerobic metabolism produces lactic acid as a cause of metabolic acidosis. Excessive intake of alcoholic beverages will also cause metabolic acidosis because of the high concentration of hydrogen ions in alcohol. Excessive intake of insulin will not result in diabetic ketoacidosis.p188, 191

Which acid-base imbalance does the nurse anticipate the patient with morbid obesity may develop?

Respiratory acidosis is related to CO 2 retention secondary to respiratory depression, inadequate chest expansion, airway obstruction, or reduced alveolar-capillary diffusion. Respiratory acidosis is common in morbidly obese patients who experience inadequate chest expansion owing to their size and work of breathing. Metabolic acidosis is related to overproduction of hydrogen ions, underelimination of hydrogen ions, underproduction of bicarbonate ions, and overelimination of bicarbonate ions. Metabolic alkalosis is related to loss of bicarbonate or buffers (i.e., vomiting or nasogastric suction). Respiratory alkalosis usually is caused by excessive loss of CO 2 through hyperventilation secondary to fever, central nervous system lesions, and salicylates. p192

A morbidly obese patient has chosen gastric bypass surgery to promote weight loss. The nurse plans to teach the patient about the need to perform monitoring to detect what disturbance consistent with rapid weight loss associated with this procedure?

Starvation, fasting, or following a strict calorie-reduced diet with rapid weight loss contributes to ketone formation and metabolic acidosis. Weight loss should decrease the work of breathing and improve hypoxemia, if present, as well as hypoventilation. Urinary retention does not occur in acid-base imbalance. 188,191

How does the body compensate for a low pH?

When the body has an acid-base imbalance, it finds ways to compensate. Low pH indicates acidosis, which the body can combat with an increased respiratory rate to blow off carbon dioxide. Decreased respirations would result in worsening acidosis. The kidneys may also respond by releasing bicarbonate, not decreasing its release. The body is already retaining carbon dioxide, so continuing to retain it would not affect low pH. p196