Acid-Base Balance

Which Acid-Base Disorder?

100

2. Metabolic alkalosis Metabolic alkalosis is defined as a deficit or loss of hydrogen ions or acids or an excess of base (bicarbonate) that results from the accumulation of base or from a loss of acid without a comparable loss of base in the body fluids. This occurs in conditions resulting in hypovolemia, the loss of gastric fluid, excessive bicarbonate intake, the massive transfusion of whole blood, and hyperaldosteronism. Loss of gastric fluid via nasogastric suction or vomiting causes metabolic alkalosis as a result of the loss of hydrochloric acid. The remaining options are incorrect interpretations.

The nurse is caring for a client with a nasogastric tube that is attached to low suction. The nurse monitors the client, knowing that the client is at risk for which acid-base disorder? 1. Metabolic acidosis 2. Metabolic alkalosis 3. Respiratory acidosis 4. Respiratory alkalosis

200

1. Metabolic acidosis Metabolic acidosis is defined as a total concentration of buffer base that is lower than normal, with a relative increase in the hydrogen ion concentration. This results from loss of buffer bases or retention of too many acids without sufficient bases, and occurs in conditions such as kidney disease; diabetic ketoacidosis; high fat diet; insufficient metabolism of carbohydrates; malnutrition; ingestion of toxins, such as acetylsalicylic acid (aspirin); malnutrition; or severe diarrhea. Intestinal secretions are high in bicarbonate and may be lost through enteric drainage tubes, an ileostomy, or diarrhea.

The nurse caring for a client with an ileostomy understands that the client is most at risk for developing which acid-base disorder? 1. Metabolic acidosis 2. Metabolic alkalosis 3. Respiratory acidosis 4. Respiratory alkalosis

300

4. Respiratory acidosis without compensation The acid-base disturbance is respiratory acidosis without compensation. The normal pH is 7.35 to 7.45. The normal Pco 2 is 35 to 45 mm Hg. In respiratory acidosis the pH is decreased and the Pco 2 is elevated. The normal bicarbonate (HCO3-) level is 22 to 27 mEq/L. Because the bicarbonate is still within normal limits, the kidneys have not had time to adjust for this acid-base disturbance. In addition, the pH is not within normal limits. Therefore the condition is without compensation.

A client who is found unresponsive has arterial blood gases drawn and the results indicate the following: pH is 7.12, Pco 2 is 90 mm Hg, and is HCO3- 22 mEq/L. The nurse interprets the results as indicating which condition? 1. Metabolic acidosis with compensation 2. Respiratory acidosis with compensation 3. Metabolic acidosis without compensation 4. Respiratory acidosis without compensation

400

3. Respiratory acidosis Respiratory acidosis is most often caused by hypoventilation in a client with COPD. Other acid-base disturbances can occur in a client with COPD during exacerbation of the disease, but the most likely imbalance is respiratory acidosis. COPD is a respiratory condition, not a metabolic one. Respiratory alkalosis is associated with hyperventilation.

The nurse plans care for a client with chronic obstructive pulmonary disease (COPD), understanding that the client is most likely to experience what type of acid-base imbalance? 1. Metabolic acidosis 2. Metabolic alkalosis 3. Respiratory acidosis 4. Respiratory alkalosis

500

Metabolic Acidosis

Which Acid-Base Disorder does Tony have and why?

Fundamental Concepts

100

The body protects itself from the acidic state by moving hydrogen ions into the cells. Therefore potassium moves out to make room for hydrogen ions and the potassium level increases.

Why does potassium rise during acidosis?

200

The cells release hydrogen ions into the blood in an attempt to increase the acidity of the blood; this forces the potassium into the cells and potassium levels decrease.

Why does potassium drop during alkalosis?

300

3.5-5.0 mEq/L

What is the normal serum potassium level?

400

Potassium Kidneys Lungs Plasma Protein system Primary buffer systems in extracellular fluid Buffers

Describe 3 mechanisms used to maintain pH?

500

Buffers

Which acid-base balance systems is the fastest.

Metabolic Alkalosis/ Metabolic Acidosis

100

4. An increased pH with an increased HCO3- Clients experiencing nausea and vomiting would most likely present with metabolic alkalosis resulting from loss of gastric acid, thus causing the pH and HCO3- to increase. Symptoms experienced by the client would include hypoventilation and tachycardia. Option 1 reflects a respiratory acidotic condition. Option 2 reflects a respiratory alkalotic condition, and option 3 reflects a metabolic acidotic condition.

A client with a 3-day history of nausea and vomiting presents to the emergency department. The client is hypoventilating and has a respiratory rate of 10 breaths/minute. The electrocardiogram (ECG) monitor displays tachycardia, with a heart rate of 120 beats/minute. Arterial blood gases are drawn and the nurse reviews the results, expecting to note which finding? 1. A decreased pH and an increased CO 2 2. An increased pH and a decreased CO 2 3. A decreased pH and a decreased HCO3- 4. An increased pH with an increased HCO3-

200

1) pH 7.29, pCO2 35 mm HG, HCO3- 17 mmol/L The pH is below normal HCO3- below normal

Pt has diabetes mellitus & metabolic acidosis. Which labs are correct? 1) pH 7.29, pCO2 35 mm HG, HCO3- 17 mmol/L 2) pH 7.31, pCO2 67 mm HG, HCO3- 32 mmol/L 3) pH 7.39, pCO2 43 mm HG, HCO3- 22 mmol/L 4) pH 7.45, pCO2 38 mm HG, HCO3- 23 mmol/L

300

Uncompensated metabolic alkalosis because an increase in pH, & an increase in HCO3, & PCO2 is normal

pH 7.49, pCO2 41 mm HG, HCO3- 38 mmol/L Is the patient compensating? alkalosis or acidosis?

400

3. Hyperaldosteronism

Which of the following is NOT a cause of metabolic acidosis? 1. Aspirin toxicity 2. Ileostomy 3. Hyperaldosteronism 4. Carbonic anhydrase inhibitors

500

1. HCO3 12, pH 7.19, PaCO2 29 This patient is at risk for metabolic acidosis, especially since they are taking Diamox (Carbonic anhydrase inhibitors which reduces the reabsorption of bicarb). HCO3 12, pH 7.19, PaCO2 29 are the only ABGs that reflect metabolic acidosis.

A patient reports taking Diamox and has been reporting confusion, fatigue, and headaches. On assessment, you note the patient is exhibiting deep and rapid respirations. Which of the following arterial blood gas findings confirm the correct acid-base imbalance for this patient given their symptoms and medication usage? (Hint look up the medication) 1. HCO3 12, pH 7.19, PaCO2 29 2. HCO3 23, pH 7.36, PaCO2 36 3. HCO3 10, pH 7.65, PaCO2 47 4. PaCO2 49, pH 7.55, HCO3 21

Respiratory Alkalosis

100

1. Nausea 2. Confusion 4. Tachycardia 6. Lightheadedness Respiratory alkalosis is defined as a deficit of carbonic acid or a decrease in hydrogen ion concentration that results from the accumulation of base or from a loss of acid without a comparable loss of base in the body fluids. This occurs in conditions that cause overstimulation of the respiratory system. Clinical manifestations of respiratory alkalosis include lethargy, lightheadedness, confusion, tachycardia, dysrhythmias related to hypokalemia, nausea, vomiting, epigastric pain, and numbness and tingling of the extremities. Hyperventilation (tachypnea) occurs.

The nurse notes that a client’s arterial blood gas results reveal a pH of 7.50 and a Pco 2 of 30 mm Hg. The nurse monitors the client for which clinical manifestations associated with these arterial blood gas results? Select all that apply. 1. Nausea 2. Confusion 3. Bradypnea 4. Tachycardia 5. Hyperkalemia 6. Lightheadedness

200

2. Potassium level of 3.0 mEq/L Respiratory alkalosis is defined as a deficit of carbonic acid or a decrease in hydrogen ion concentration that results from the accumulation of base or from a loss of acid without a comparable loss of base in the body fluids. This occurs in conditions that cause overstimulation of the respiratory system. Clinical manifestations of respiratory alkalosis include lethargy, lightheadedness, confusion, tachycardia, dysrhythmias related to hypokalemia, nausea, vomiting, epigastric pain, and numbness and tingling of the extremities. The correct option identifies the presence of hypokalemia.

The nurse is caring for a client who is on a mechanical ventilator. Blood gas results indicate a pH of 7.50 and a Pco 2 of 30 mm Hg. The nurse has determined that the client is experiencing respiratory alkalosis. Which laboratory value would most likely be noted in this condition? 1. Sodium level of 145 mEq/L 2. Potassium level of 3.0 mEq/L 3. Magnesium level of 2.0 mg/dL 4. Phosphorus level of 4.0 mg/dL

Respiratory Acidosis

100

1. pH 7.25, Pco 2 50 mm Hg Atelectasis is a condition characterized by the collapse of alveoli, preventing the respiratory exchange of oxygen and carbon dioxide in a part of the lungs. The normal pH is 7.35 to 7.45. The normal Pco 2 is 35 to 45 mm Hg. In respiratory acidosis, the pH is decreased and the Pco 2 is elevated. Option 2 identifies normal values.

The nurse reviews the blood gas results of a client with atelectasis. The nurse analyzes the results and determines that the client is experiencing respiratory acidosis. Which result validates the nurse’s findings? 1. pH 7.25, Pco 2 50 mm Hg 2. pH 7.35, Pco 2 40 mm Hg 3. pH 7.50, Pco 2 52 mm Hg 4. pH 7.52, Pco 2 28 mm Hg