MEDSURG: AQ - Chapter 12, Assessment and Care of Patients With Problems of Acid-Base Balance

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

-Confusion -Warm, flushed, dry skin Rationale: 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.

Which conditions place a patient at risk for developing metabolic alkalosis? Select all that apply.

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What is one of the causes of respiratory alkalosis?

-Anxiety Rationale: 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.

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

-Diarrhea -Liver failure -Kidney failure Rationale: Diarrhea, liver failure, and kidney failure can result in metabolic acidosis. Airway obstruction and respiratory depression may result in respiratory acidosis.

What is one of the causes of acidosis?

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

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

-Lungs and kidneys Rationale: 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.

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

-Maintaining blood glucose level within normal limits. Rationale: 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.

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?

-Normal pH on arterial blood gases Rationale: 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.

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

-Overproduction of hydrogen ions Rationale: 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.

A lab report for a 47-year-old patient shows the following results: pH 7.32; bicarbonate 24; PaO 2 77; PaCO 2 48. These findings are consistent with which acid-base imbalance?

-Respiratory Acidosis Rationale: In respiratory acidosis, there is a decrease in pH (normal is 7.35-7.45), a normal bicarbonate (normal is 21-28), a decreased PaO 2 (normal is 80-100), and an increased PaCO 2 (normal is 35-45). The arterial blood gas results of pH 7.32; bicarbonate 24; PaO 2 77; PaCO 2 48 reflect respiratory acidosis. In respiratory alkalosis, there is an increase in pH, a normal bicarbonate, a normal PaO 2, and a decrease in PaCO 2. In metabolic alkalosis, there is an increase in pH, increase bicarbonate, normal PaO 2, and normal PaCO 2. In metabolic acidosis, there is a decrease in pH, decrease bicarbonate, normal PaO 2, and normal PaCO 2.

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

-Respiratory acidosis Rationale: 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.

After a motor vehicle crash, the nurse is consoling a patient in the emergency department who is hysterical and hyperventilating after being notified of the death of a family member. What acid-base imbalance is this patient likely to develop?

-Respiratory alkalosis

Which arterial blood gas laboratory values would be seen in metabolic alkalosis?

-pH 7.49, HCO 3 - 32 Rationale: In metabolic alkalosis, pH is greater than 7.45 and HCO 3 - is greater than 28. pH 7.28 and CO 2 54 = respiratory acidosis (pH < 7.35, CO 2 >45). pH 7.53 and CO 2 28 = respiratory alkalosis (pH > 7.45, CO 2 < 35). pH 7.31 and HCO 3 - 18 = metabolic acidosis (pH < 7.35, HCO 3 - < 21).