PrepU Chapter 40 | Exam 1
To calculate the H2CO3 content of the blood, the nurse needs to measure the Pco2 (partial pressure of CO2) by its solubility coefficient. What is the solubility coefficient of CO2?
*0.03* Rationale: The H2CO3 content of the blood can be calculated by multiplying the partial pressure of CO2 (Pco2) by its solubility coefficient, which is 0.03.
The nurse is providing care for several clients on a medical unit. Which client likely has the highest risk for developing an acid-base imbalance?
*A client who is being treated for acute kidney injury and who requires dialysis* Rationale: Because of the key role that the kidneys play in the maintenance of acid-base balance, individuals with kidney disease are vulnerable to acid-base disorders. Anaphylaxis, syphilis and fistulas do not present particular risks for acid-base imbalances.
Which is the primary mechanism for transporting carbon dioxide (CO2) in the body?
*As bicarbonate in the plasma* Carbon dioxide (CO2), the byproduct of metabolism, is transported in three ways: as a dissolved gas, as bicarbonate (HCO3-), and attached to hemoglobin with a reversible bond as carbaminohemoglobin. The primary transport method is in the form of bicarbonate in the plasma.
An older adult has had a "sour stomach" and has treated it at home by taking frequent doses of baking soda (sodium bicarbonate). What nursing action is most appropriate?
*Assess the client for signs and symptoms of hypokalemia* Rationale: Ingestion of sodium bicarbonate causes metabolic alkalosis with a consequent risk of hypokalemia. Fomepizole is an antidote to ethylene glycol poisoning and metabolic acidosis. A hypertonic intravenous solution would not resolve the client's acid-base imbalance.
A client has been diagnosed with metabolic acidosis. What assessment finding does the nurse expect?
*Decreased pH below 7.35* Rationale: In metabolic acidosis, the client's pH will decrease below 7.35 or normal range. In addition , the client's HC03- will decrease to below 22 mEq/L.
A client has been admitted to the intensive care unit after recovering from cardiogenic shock. In the hours since admission, the client's arterial blood gases indicate acidosis, most likely acute lactic acidosis. Which signs, symptoms, and diagnostic findings might his care team anticipate before acid--base balance is restored?
*Dysrhythmias* Rationale: As with any form of acidosis, pH is apt to be lower than normal. Metabolic acidosis is also associated with dysrhythmias, decreased alertness, and nausea and vomiting. Respiration is likely to be increased in both rate and depth.
Respiratory alkalosis can be caused by a respiratory rate in excess of that which maintains normal plasma Pco2 levels. What is a common cause of respiratory alkalosis?
*Hyperventilation* Rationale: One of the most common causes of respiratory alkalosis is hyperventilation, which is characterized by episodes of over breathing, often associated with anxiety.
The nurse is reviewing the following lab results of a client diagnosed with renal failure: pH: 7.24 PCO2: 38 mm Hg HCO3:18 mEq/L The nurse would interpret this as:
*Metabolic acidosis* Rationale: Metabolic acidosis would be diagnosed based on the findings related to a low pH level (<7.3) and a low bicarbonate level. Respiratory acidosis represents a decreased pH and an increased PCO2, metabolic alkalosis represents an increased pH and a increased HCO3, and respiratory alkalosis represents an increased pH and a decreased PCO2.
The student is studying buffer systems. Which of the following is the largest buffer system in the body?
*Proteins* Rationale: Proteins are the largest buffer system in the body
A client's arterial blood gases include the following: pH: 7.29 HCO3-: 18 mmol/L PCO2: 36 mm Hg PO2: 94 mm Hg What response by the nurse is the most appropriate?
*Replace fluids and electrolytes as ordered.* Rationale: The client's low pH and HCO3- coupled with normal oxygen and carbon dioxide levels are suggestive of metabolic acidosis. Fluid and electrolyte replacement is necessary, but a hypertonic solution would not be used.
A patient with acquired immune deficiency anemia is taking several medications to control the disease. Which of the following medications taken by the patient is the nurse concerned may be causing the patient's severe lactic acidosis?
*Zidovudine (AZT)* A variety of drugs can produce life-threatening lactic acidosis by inhibiting mitochondrial function. These drugs include the biguanide antidiabetic drugs (metformin) and the antiretroviral nucleoside reverse transcriptase inhibitors (zidovudine [AZT]).
The nurse is caring for a client with acute primary respiratory acidosis. When determining the cause of the acidosis the nurse is aware that which of these is most common?
*a) Impaired alveolar ventilation* b) Renal bicarbonate retention c) Increased metabolic acids d) Decreased CO2 retention Rationale: Acute respiratory acidosis is frequently caused by impaired alveolar ventilation with CO2 retention. Increased metabolic acids, such as lactic acid, are characteristic of metabolic acidosis. Bicarbonate retention is a compensatory response to respiratory acidosis, or it can be the cause of metabolic alkalosis when retention is excessive.
The nurse is caring for a client who has excessive diarrhea. Which of these acid base disturbances does the nurse anticipate uncovering during evaluation of the arterial blood gas?
*a) Metabolic acidosis* b) No change in values from normal c) Increased pH value d) An increase in bicarbonate Rationale: The client who has diarrhea has increased loss of bicarbonate from the intestinal tract, which results in metabolic acidosis. The other answers are incorrect. The pH value would be decreased, and the bicarbonate would be decreased.
Which conditions place clients at risk for respiratory acidosis? Select all that apply.
*a) Morbid obesity* *b) Kyphoscoliosis* c) Diabetes mellitus *d) Drug overdose* *e) Pneumonia* Rationale: Respiratory acidosis is caused by conditions that suppress respirations or impair alveolar ventilation. These include drug overdose, head injury, lung diseases such as asthma, emphysema, chronic bronchitis, pneumonia, pulmonary edema and respiratory distress syndrome. Airway obstruction also causes respiratory acidosis. This could be caused by chest injury, kyphoscoliosis (spinal curvature), extreme obesity, or treatment with paralytic medications.
The nurse is caring for the following group of clients. Select the client most likely to be diagnosed with respiratory alkalosis.
A 26-year-old female with anxiety who has been hyperventilating
The nurse is reviewing the medication administration record (MAR) of a client with metabolic acidosis. Which medications in the MAR could contribute to the metabolic acidosis? Select all that apply.
*a) Zidovudine (AZT)* b) Captopril (Capoten) *c) Metformin (Glucophage)* *d) Acetylsalicylic acid (Bufferin)* e) Amoxicillin (Amoxil) Rationale: A number of medications inhibit mitochondrial function which can lead to lactic acidosis as a cause of metabolic acidosis. These include biguanide oral antidiabetic agents such as metformin (Glucophage); antiretroviral nucleoside reverse transcriptase inhibitors (NRTIs), and medications such as zidovudine (AZT) used to treat HIV/AIDS. Aspirin toxicity can also lead to acidosis.
The nurse caring for a client with respiratory alkalosis examines arterial blood gas (ABG) results. Which change from the initial value indicates the client's respiratory alkalosis is improving?
*pH has decreased* Rationale: In respiratory alkalosis, the client has a net loss of carbon dioxide (CO2) which creates a rise in pH. The pH needs to move away from alkalosis, which is the high end of the pH scale, for the client's condition to demonstrate improvement. To lower the pH, either the carbon dioxide (CO2) level needs to increase or the bicarbonate level needs to decrease.
The body regulates the pH of its fluids by what mechanism? (Select all that apply.)
*• Chemical buffer systems of the body fluids* *• The lungs * *• The kidneys* Rationale: The pH of body fluids is regulated by three major mechanisms: (1) chemical buffer systems of the body fluids, which immediately combine with excess acids or bases to prevent large changes in pH; (2) the lungs, which control the elimination of CO2; and (3) the kidneys, which eliminate H+ and both reabsorb and generate HCO3-.
A nurse is providing care for several clients on an acute medicine unit. Which client should the nurse recognize as being at the highest risk for metabolic alkalosis?
A client on continuous nasogastric suction and whose hypertension is being treated with diuretics
In which client would the nurse be most likely to assess the signs and symptoms of an acid-base imbalance?
A client with chronic obstructive pulmonary disease whose most recent arterial blood gasses reveal a PCO2 of 51 mm Hg
The nurse is caring for a client with an acid base imbalance. Which of these does the nurse recognize is correct regarding compensation?
A pH moves toward the normal range
A client's most recent laboratory results suggest the presence of metabolic alkalosis. What action by the nurse best addresses a potential cause of this acid-base imbalance?
Administering an antiemetic to treat the client's frequent vomiting
There are both metabolic and respiratory effects on the acid-base balance in the body. How do metabolic disorders change the pH of the body?
Alter the plasma Hco3- Explanation: Metabolic disorders produce an alteration in the plasma HCO3- concentration and result from the addition or loss of nonvolatile acid or alkali to or from the extracellular fluids. None of the other answers are correct.
The nurse is caring for a client who has excessive diarrhea. Which of these acid base disturbances does the nurse anticipate uncovering during evaluation of the arterial blood gas?
An increase in bicarbonate
As other mechanisms prepare to respond to a pH imbalance, immediate buffering is a result of increased:
Bicarbonate/carbonic acid regulation
The nurse caring for a client with respiratory acidosis examines arterial blood gas (ABG) results. Which change from the initial value indicates the client's respiratory acidosis is improving?
COs has decreased
The nurse recognizes the role of the lungs in acid-base balance is regulation of which of the following?
CO₂
A child accidentally consumes a container of wood alcohol. The ED physician knows that the child is at risk of developing which of the following?
Metabolic acidosis
The client with a small bowel obstruction has a nasogastric tube to low, continuous suction. The nurse explains that this treatment places the client at risk for which of the following?
Metabolic alkalosis
The nurse is administering calcium carbonate, as a phosphate binder, to a client in chronic renal failure. The nurse explains that this chronic ingestion can lead to which of the following?
Metabolic alkalosis
The renal control mechanism of restoring the acid-base balance is accomplished through which process?
Reabsorption of HCO3 and excretion of H+ restores acid-base balance through the renal control mechanisms.
The condition of a client with metabolic acidosis from an intestinal fistula is not improving. The pulse is 125 beats/min and the BP 84/56mm Hg. ABG values are: pH 7.1, HCO3- 18 mEq/L, PCO2 57mm Hg. What IV medication should the nurse expect to provide next?
Sodium bicarbonate
What is the nurse's expectation about a client's ability to compensate for a metabolic blood gas disorder?
The client will compensate with the respiratory system.
A client has been admitted to the hospital after losing 20 kg (44 lb) over the past 3 months, largely due to frequent induction of vomiting. What intervention should the nurse anticipate in the treatment of the client's resulting acid-base imbalance?
a) Fluid replacement with an intravenous solution containing KCl as prescribed b) Supplementary oxygen using a non-rebreather mask c) Administration of intravenous sodium bicarbonate as prescribed d) Mechanical ventilation and administration of supplementary oxygen A
A client with ethylene glycol toxicity is restless, and stating he has flank pain. What intervention should the nurse perform to minimize complications?
a) Give aspirin for pain *b) Increase IV fluids* c) Reduce dietary calcium d) Encourage ambulation Rationale: Symptoms of ethylene glycol toxicity appear in stages. Within the first 12 hours, the client may appear drunk or comatose. In the second stage the client may develop tachycardia or pulmonary edema. During the third stage, the client may develop flank pain and renal failure as the tubules become plugged with oxalate crystals. Expanding extracellular fluid volume and hemodialysis are used to flush the toxins from the system. Aspirin is not a drug of choice because it is metabolized in the kidney.
What assessment would a nurse expect when caring for a client with metabolic alkalosis? Select all that apply.
a) Hyperactive reflexes b) Constipation *c) Dysrhythmias* d) Increased urine acidity *e) Hyperventilation* Rationale: Conditions that cause acidosis suppress neural excitability, so as the condition progresses, clients become lethargic, stuporous, or comatose. By comparison, alkalosis causes irritability, hyperactive reflexes, and sometimes convulsions. Life-threatening dysrhythmias may occur. The kidneys attempt to conserve hydrogen ions, decreasing the urine acidity. When the lungs compensate, the client will have slow, shallow breathing.
A client has these arterial blood gas values: anion gap 20 mEq/L, pH 7.29, pCO2 37mm Hg, HCO3- 11 mEq/L, base excess -6 mEq/L. With what condition do these values correspond?
a) Hyperkalemia b) Lactic acidosis c) Multiple myeloma d) lithium toxicity B
The nurse is caring for a client with worsening respiratory acidosis. Which of these interventions does the nurse anticipate if the client's condition continues to deteriorate?
a) Mechanical ventilation b) Introduction of large muscle exercise c) Resolution of the underlying emotional cause d) Reducing the amount of supplemental oxygen A
A client with a long history of alcohol abuse has been admitted to the emergency department after several of days of heavy drinking. The nurse can best promote the restoration of the client's acid-base balance by:
administering intravenous sodium bicarbonate as prescribed.
By reabsorbing HCO3- from the glomerular filtrate and excreting H+ from the fixed acids that result from lipid and protein metabolism, the kidneys work to return or maintain the pH of the blood to normal or near-normal values. How long can this mechanism function when there is a change in the pH of body fluids?
days Explanation: The renal mechanisms for regulating acid-base balance cannot adjust the pH within minutes, as respiratory mechanisms can, but they continue to function for days, until the pH has returned to normal or near-normal range. It is the respiratory system that responds within minutes to return the body's pH near to its normal limits.
A patient informs the nurse of a problem with acid indigestion and has been taking large amounts of calcium carbonate antacids daily but still has no relief. The patient states that he can consume a bottle of 100 antacids in 4 days. Which of the following blood gas results does the nurse anticipate assessing?
pH 7.6
The nurse caring for a client with metabolic acidosis examines arterial blood gas (ABG) results. Which change from the initial value indicates the client's metabolic acidosis is improving?
pH has increased
The nurse is caring for a client with metabolic alkalosis. Which of these arterial blood gas results supports this diagnosis?
pH of 7.50 and HCO3 of 45 mEq/L