PREPU - acid-base balance

When evaluating a client's arterial blood gases (ABGs), which value is consistent with metabolic alkalosis?

pH 7.48 Metabolic alkalosis is a clinical disturbance characterized by a high pH and high plasma bicarbonate concentration. The HCO3 value is below normal. The PaCO2 value and the oxygen saturation level are within a normal range.

The nurse is caring for a client diagnosed with chronic obstructive pulmonary disease (COPD) and experiencing respiratory acidosis. The decrease in pH exists because the client's lungs:

are unable to blow off carbon dioxide. In clients with chronic respiratory acidosis, the client is unable to blow off carbon dioxide leaving in increased amount of hydrogen in the system. The increase in hydrogen ions leads to acidosis. In COPD, the client is able to breathe in oxygen and gas exchange can occur, but the lungs' ability to remove carbon dioxide from the system is compromised. Although individuals with COPD frequently have a history of smoking, impaired ciliary function is not the cause of the acidosis.

The nurse assesses a child with ketoacidosis. What manifestations are supportive of the diagnosis of ketoacidosis?

deep, rapid respirations. The accumulation of ketones, organic acids that readily release free hydrogen ions causing blood pH to fall, leads to ketoacidosis. To compensate, the respiratory buffering system is activated, which results in the child taking deep, rapid breaths to rid the body of excess carbon dioxide. This characteristic breathing pattern is known as Kussmaul's respirations. Typically with ketoacidosis, the pulse rate would be more rapid and weak due to dehydration and loss of electrolytes. Typically with ketoacidosis, the skin would be dry due to dehydration. With ketoacidosis, hypotension results from the contracted blood volume secondary to dehydration.

On admission, the client's arterial blood gas (ABG) values were: pH, 7.20; PaO2, 64 mm Hg (8.5 kPa); PaCO2, 60 mm Hg (8 kPa); and HCO3-, 22 mEq/L (22 mmol/L). A chest tube is inserted, and oxygen at 4 L/minute is started. Thirty minutes later, repeat blood gas values are: pH, 7.30; PaO2, 76 mm Hg (10.1 kPa); PaCO2, 50 mm Hg (6.7 kPa); and HCO3-, 22 mEq/L (22 mmol/L). This change would indicate:

improving respiratory status. The ABG values after chest tube insertion are returning to normal, indicating that treatment is effective.Impending respiratory failure would be indicated by a decreasing PaO2 or an increasing PaCO2.The client is not alkalotic because the pH values are below 7.35.If the chest tubes were obstructed, the client's respiratory status would deteriorate.

A client's arterial blood gas values are shown. The nurse should develop a care plan based on the fact the client is experiencing which clinical situation?

metabolic acidosis The pH of 7.24 indicates that the client is acidotic. The carbon dioxide level is normal, but the HCO3- level is decreased. These findings indicate that the client is in metabolic acidosis.

A client has these arterial blood gas values: pH, 7.30; PaO2, 89 mm Hg; PaCO2, 50 mm Hg; and HCO3-, 26 mEq/L. Based on these values, the nurse should suspect which condition?

respiratory acidosis This client has a below-normal (acidic) blood pH value and an above-normal partial pressure of arterial carbon dioxide (PaCO2) value, indicating respiratory acidosis. In respiratory alkalosis, the pH value is above normal and the PaCO2 value is below normal. In metabolic acidosis, the pH and bicarbonate (HCO3-) values are below normal. In metabolic alkalosis, the pH and HCO3- values are above normal.

A nurse is caring for a client admitted with a diagnosis of exacerbation of myasthenia gravis. Upon assessment of the client, the nurse notes the client has severely depressed respirations. The nurse would expect to identify which acid-base disturbance?

respiratory acidosis Respiratory acidosis is always from inadequate excretion of CO2 with inadequate ventilation, resulting in elevated plasma CO2 concentrations. Respiratory acidosis can occur in diseases that impair respiratory muscles such as myasthenia gravis.

A client has been diagnosed with an intestinal obstruction and has a nasogastric tube set to low continuous suction. Which acid-base disturbance is this client at risk for developing?

metabolic alkalosis Metabolic alkalosis is a clinical disturbance characterized by a high pH and a high plasma biacarbonate concentration. The most common cuase of metabolic alkalosis is vomiting or gastric suction with loss of hydrogen and choloride ions. Gastric fluid has an acid pH, and loss of this acidic fluid increases the alkalinity of body fluids.

As status asthmaticus worsens, the nurse would expect the client to experience which acid-base imbalance?

respiratory acidosis As status asthmaticus worsens, the PaCO increases and the pH decreases, reflecting respiratory acidosis.

A client has a dull headache, is dizzy, and has an increased pulse rate. The results of arterial blood gas analysis are as follows: pH 7.26; partial pressure of carbon dioxide, 50 mm Hg (6.7 kPa); and bicarbonate, 24 mEq/L (24 mmol/L). These findings indicate which acid-base imbalance?

respiratory acidosis The pH of 7.26 indicates that the body is in a state of acidosis. The elevated partial pressure of carbon dioxide value accompanied by a normal bicarbonate value indicates that the acid-base imbalance is respiratory acidosis. The additional clinical findings of headache, dizziness, and increased pulse rate, resulting from the elevated partial pressure of carbon dioxide, further support this diagnosis.

Before weaning a client from a ventilator, which assessment parameter is the most important for the nurse to obtain?

baseline arterial blood gas (ABG) levels Before weaning the client from mechanical ventilation, it's most important to have baseline ABG levels. During the weaning process, ABG levels will be checked to assess how the client is tolerating the procedure. Other assessment parameters are less critical. Measuring fluid volume intake and output is always important when a client is being mechanically ventilated. Prior attempts at weaning and ECG results are documented on the client's record, and the nurse can refer to them before the weaning process begins.

The nurse is interpreting blood gases for a client with acute respiratory distress syndrome (ARDS). Which set of arterial blood gas values does the nurse expect for this client?

pH 7.25, PaCO2 48, HCO3 24 The nurse would expect a client with ARDS to exhibit respiratory acidosis. The results of pH 7.25, PaCO2 48, HCO3 24 indicate respiratory acidosis. Results of pH 7.29, PaCO2 36, HCO3 19 indicate metabolic acidosis and results of pH 7.30, PaCO2 28, HCO3 16 indicate metabolic acidosis with partial compensation, which would be expected in a client with a metablic problem such as diabetic ketoacidosis. Results of pH 7.35, PaCO2 46, HCO3 30 indicate fully compensated respiratory acidosis, which would be expected for client with a chronic respiratory problem.

A nurse is reviewing arterial blood gas (ABG) results on four clients. Which results would the nurse report immediately to the healthcare provider?

pH 7.31, PaO2 84 mmHg, PaCO2 50 mmHg, HCO3 24 mEq/L, and O2 sat 90% This ABG of pH 7.31, PaO2 84 mmHg, PaCO2 50 mmHg, HCO3 24 mEq/L, and O2 sat 90% indicates uncompensated respiratory acidosis and would be reported to the healthcare provider immediately. The results pH 7.35, PaO2 82 mmHg, PaCO2 44 mmHg, HCO3 22 mEq/L, and O2 sat 95% are normal values. The results pH 7.45, PaO2 90 mmHg, PaCO2 28 mmHg, HCO3 32 mEq/L, and O2 sat 98% and pH 7.36, PaO2 86 mmHg, PaCO2 55 mmHg, HCO3 30 mEq/L, and O2 sat 90% both indicate fully compensated acid-base imbalances; they would not be the priority for reporting to the healthcare provider.

The nurse has received lab reports for several clients undergoing care. Which set of arterial blood gas (ABG) results will the nurse investigate first?

pH 7.49, PaCO2 30 mmHg, PaO2 75 mmHg, and HCO3- 22 mEq/L The ABG results pH 7.49, PaCO2 30 mmHg, PaO2 75 mmHg, and HCO3- 22 mEq/L indicate respiratory alkalosis. The pH level is increased, the PaCO2 levels are decreased and the HCO3 is normal. The decreased PaO2 indicates this client is in respiratory distress. Therefore, the nurse would investigate this result first. Normal values are pH 7.35 to 7.45, PaCO2 35 to 45 mmHg, and HCO3- 22 to 26 mEq/L. Results of pH 7.35, PaCO2 48 mmHg, PaO2 91 mmHg, and HCO3- 28 mEq/L indicate a fully compensated respiratory acidosis, making this less urgent. Results of pH 7.47, PaCO2 43 mmHg, PaO2 99 mmHg, and HCO3- 29 mEq/L indicate metabolic alkalosis, which is not the priority. Results of pH 7.34, PaCO2 36 mmHg, PaO2 95 mmHg, HCO3- 20 mEq/L indicate mild metabolic acidosis, which would also be less urgent than the respiratory alkalosis.

The nurse is analyzing the arterial blood gas (AGB) results of a client diagnosed with severe pneumonia. What ABG results are most consistent with this diagnosis?

pH: 7.20, PaCO2: 65 mm Hg, HCO3-: 26 mEq/L Respiratory acidosis is a clinical disorder in which the pH is less than 7.35 and the PaCO2 is greater than 42 mm Hg and a compensatory increase in the plasma HCO3- occurs. It may be either acute or chronic. The ABG of pH: 7.32, PaCO2: 40 mm Hg, HCO3-: 18 mEq/L indicates metabolic acidosis. The ABGs of pH: 7.50, PaCO2: 30 mm Hg, and HCO3-: 24 mEq/L indicate respiratory alkalosis. The ABGs of pH 7.42, PaCO2: 45 mm Hg, and HCO3-: 22 mEq/L indicate a normal result/no imbalance.

In chronic obstructive pulmonary disease (COPD), decreased carbon dioxide elimination results in increased carbon dioxide tension in arterial blood, leading to what acid-base imbalance?

respiratory acidosis Increased carbon dioxide tension in arterial blood leads to respiratory acidosis and chronic respiratory failure. In acute illness, worsening hypercapnia can lead to acute respiratory failure. The other acid-base imbalances would not correlate with COPD.

The nurse is caring for a 12-month-old infant with dehydration and metabolic acidosis. What assessment finding does the nurse document as congruent with dehydration and metabolic acidosis?

tachypnea The nurse would expect to see tachypnea because the body compensates for metabolic acidosis via the respiratory system, which tries to eliminate carbon dioxide by increasing alveolar ventilation through deep, rapid respirations. The cardiovascular symptoms the nurse would observe would be poor perfusion, weak pulses, and tachycardia, not bradycardia. The child may also be hypotensive, but unless there is a respiratory disorder or polycythemia, the nurse would not expect to see cyanosis.

Which physical sensation will the client who has had an abdominal hysterectomy most likely experience if she hyperventilates while performing deep-breathing exercises?

dizziness Hyperventilation occurs when the client breathes so rapidly and deeply that she exhales excessive amounts of carbon dioxide. A characteristic symptom of hyperventilation is dizziness. To avoid hyperventilation, the nurse should assist the client in the practice of slow, deep breathing in a regular breathing pattern. Dyspnea, blurred vision, and mental confusion are not associated with hyperventilation.

The nurse assesses an adolescent client with lethargy, retractions of the intercostal spaces, a persistent expiratory wheeze, diminished breath sounds, tachycardia, and tachypnea. Arterial blood gas results are pH 7.10; PCO2 80 mm Hg (10.64 kPa); PO2 35 mm Hg (4.66 kPa), HCO3 29 mEq/l (29 mmol/l). What is the priority condition the nurse must address?

respiratory acidosis Based on the results of the arterial blood gases, this client is in respiratory acidosis. The nurse must address this quickly because it could lead to respiratory failure. If the nurse addresses the respiratory acidosis quickly, which means also addressing the cause of the imbalance, the client may not experience respiratory failure. Additionally, assessment data, vital signs, and laboratory work will begin to normalize.

A 75-year-old client who complains of a "sour stomach" has been taking baking soda (sodium bicarbonate) regularly as a self-treatment. This may place the client at risk for what acid-base imbalance?

metabolic alkalosis Metabolic alkalosis results in increased plasma pH because of accumulated base bicarbonate or decreased hydrogen ion concentrations. Regular use of baking soda (sodium bicarbonate) may place the client at risk for this condition. Metabolic acidosis refers to decreased plasma pH because of increased organic acids (acids other than carbonic acid) or decreased bicarbonate. Respiratory acidosis, which may be either acute or chronic, is caused by excess carbonic acid. Respiratory alkalosis results from a carbonic acid deficit that occurs when rapid breathing releases more CO2 than necessary with expired air.

A client's arterial blood gas values are as shown on the accompanying chart. These findings indicate which of the following acid-base imbalances?

Metabolic acidosis. The pH of 7.24 indicates that the client is acidotic. The carbon dioxide level is normal, but the HCO3- level is decreased. These findings indicate that the client is in metabolic acidosis.

A client with a suspected overdose of an unknown drug is admitted to the emergency department. Arterial blood gas values indicate respiratory acidosis. What should the nurse do first?

Prepare to assist with ventilation. Respiratory acidosis is associated with hypoventilation; in this client, hypoventilation suggests intake of a drug that has suppressed the brain's respiratory center. Therefore, the nurse should assume the client has respiratory depression and should prepare to assist with ventilation. After the client's respiratory function has been stabilized, the nurse can safely monitor the heart rhythm, prepare for gastric lavage, and obtain a urine specimen for drug screening.

A client experiencing a severe asthma attack has the following arterial blood gas results: pH 7.33; Pco2 48 mm Hg (6.4 kPa); Po2 58 mm Hg (7.7 kPa); HCO3 26 mEq/L (26 mmol/L). Which prescription should the nurse implement first?

albuterol nebulizer The arterial blood gas reveals a respiratory acidosis with hypoxia. A quick-acting bronchodilator, albuterol, should be administered via nebulizer to improve gas exchange. Ipratropium is a maintenance treatment for bronchospasm that can be used with albuterol. A chest X-ray and sputum sample can be obtained once the client is stable.

The nurse is concerned about the risks of hypoxemia and metabolic acidosis in a client who is in shock. What finding should the nurse analyze for evidence of hypoxemia and metabolic acidosis in a client with shock?

arterial blood gas (ABG) findings Analysis of ABG findings is essential for evidence of hypoxemia and metabolic acidosis. Low RBCs and hemoglobin correlate with hypovolemic shock and can lead to poor oxygenation. An elevated white blood cell count supports septic shock. Oxygen saturation levels are usually affected by hypoxemia but cannot be used to diagnose acid-base imbalances such as metabolic acidosis.

A client who is 16 hours postoperative rates pain as 7 out of 10, has a respiratory rate of 28 breaths/min, and an arterial blood gas (ABG) result of pH 7.47, CO2 33 mm Hg (4.39 kPa), and HCO3 26 mEq/L (26 mmol/L). Which action should the nurse take?

Administer I.V. morphine sulfate 4 mg as prescribed The client is experiencing respiratory alkalosis caused by the increased respiratory rate due to incisional pain and anxiety. The nurse's first action should be to medicate the client for pain. There is no indication that the client requires oxygen. Teaching proper breathing is not effective if the client is experiencing pain. The ABG results are only slightly abnormal and should correct if pain is adequately treated so there is no indication to notify the health care provider.

A nurse is assessing a 6-month-old infant at a well-baby check. The parent says that the infant has been having diarrhea for the last 2 days. Which is the nurse's priority action?

Collect more data from parent about the diarrhea. The nurse should obtain a more detailed history and assessment on the infant to determine the next steps in care. Routine teaching, use of the emergency department, or notifying the primary healthcare provider is not a priority until the diarrhea is evaluated.

A client hospitalized for treatment of a pulmonary embolism develops respiratory alkalosis. Which clinical findings commonly accompany respiratory alkalosis?

light-headedness or paresthesia The client with respiratory alkalosis may complain of light-headedness or paresthesia (numbness and tingling in the arms and legs). Nausea, vomiting, abdominal pain, and diarrhea may accompany respiratory acidosis. Hallucinations and tinnitus rarely are associated with respiratory alkalosis or any other acid-base imbalance.

A client who has been recently extubated has shortness of breath. The nurse reports the client's discomfort and the results of the recently prescribed arterial blood gas analysis to the health care provider (HCP). After reviewing the report of the complete blood count (see report), the nurse should also report which results to the HCP?

hemoglobin and hematocrit The nurse should review the CBC with differential to evaluate the client's hemoglobin and hematocrit, which are abnormal and should be reported to the HCP. Anemia leads to decreased oxygen-carrying capacity of the blood. A client unable to compensate for the anemia may experience a profound sense of dyspnea. There has been a significant drop in the hemoglobin and hematocrit since the previous report, and these should be reported to the HCP. The monocytes are within normal range. HA1c is a laboratory test evaluating glycosylated hemoglobin and is in the normal range. This test is used to diagnose diabetes and/or monitor diabetic glucose control over time. PT is a coagulation study reflecting liver function and clotting time and is in the normal range.

A client has the following arterial blood gas (ABG) values: pH, 7.12; partial pressure of arterial carbon dioxide (PaCO2), 40 mm Hg; and bicarbonate (HCO3-), 15 mEq/L. These ABG values suggest which disorder?

metabolic acidosis This client's pH value is below normal, indicating acidosis. The HCO3- value also is below normal, reflecting an overwhelming accumulation of acids or excessive loss of base, which suggests metabolic acidosis. The PaCO2 value is normal, indicating absence of respiratory compensation. These ABG values eliminate respiratory alkalosis, respiratory acidosis, and metabolic alkalosis.

A client with emphysema is at a greater risk for developing what acid-base imbalance?

chronic respiratory acidosis Respiratory acidosis, which may be either acute or chronic, is caused by excess carbonic acid, which causes the blood pH to drop below 7.35. Chronic respiratory acidosis is associated with disorders such as emphysema, bronchiectasis, bronchial asthma, and cystic fibrosis.

A client in the emergency department reports that they have been vomiting excessively for the past 2 days. The client's arterial blood gas analysis shows a pH of 7.50, partial pressure of arterial carbon dioxide (PaCO2) of 43 mm Hg, partial pressure of arterial oxygen (PaO2) of 75 mm Hg, and bicarbonate (HCO3-) of 42 mEq/L. Based on these findings, the nurse documents that the client is experiencing which type of acid-base imbalance?

metabolic alkalosis A pH over 7.45 with a HCO3- level over 26 mEq/L indicates metabolic alkalosis. Metabolic alkalosis is always secondary to an underlying cause and is marked by decreased amounts of acid or increased amounts of base HCO3-. The client isn't experiencing respiratory alkalosis because the PaCO2 is normal. The client isn't experiencing respiratory or metabolic acidosis because the pH is greater than 7.35.

A client is admitted to the emergency department with a broken humerus after a motor vehicle collision. Significant assessment findings include respiratory rate 28 breaths/min and arterial blood gas (ABG) readings of pH 7.51, PaCO2 30 mm Hg (3.99 kPa), HCO3 23 mEq/L (23 mmol/L), and PaO2 90 mm Hg (11.97 kPa). Which nursing action would be a priority?

Offer reassurance, and treat the client's pain.

A nurse assesses arterial blood gas results for a client in acute respiratory failure (ARF). Which result is consistent with this disorder?

pH 7.28, PaO2 50 mm Hg ARF is defined as a decrease in the arterial oxygen tension (PaO2) to less than 50 mm Hg (hypoxemia) and an increase in arterial carbon dioxide tension (PaCO2) to greater than 50 mm Hg (hypercapnia), with an arterial pH of less than 7.35.

An adolescent is admitted for treatment of bulimia nervosa. When developing the care plan, the nurse anticipates including interventions that address which metabolic disorder?

metabolic alkalosis In a client with bulimia nervosa, metabolic alkalosis may occur secondary to hydrogen loss caused by frequent, self-induced vomiting. Typically, the blood glucose level is within normal limits, making hypoglycemia unlikely. In bulimia nervosa, hypokalemia is more common than hyperkalemia and typically results from potassium loss related to frequent vomiting.

A client presents to the emergency department, reporting that they have been vomiting every 30 to 40 minutes for the past 8 hours. Frequent vomiting puts this client at risk for which imbalances?

metabolic alkalosis and hypokalemia Gastric acid contains large amounts of potassium, chloride, and hydrogen ions. Excessive vomiting causes loss of these substances, which can lead to metabolic alkalosis and hypokalemia. Excessive vomiting doesn't cause metabolic acidosis or hyperkalemia.

A client comes to the emergency department with status asthmaticus. The client's respiratory rate is 48 breaths/minute, and the client is wheezing. An arterial blood gas analysis reveals a pH of 7.52, a partial pressure of arterial carbon dioxide (PaCO2) of 30 mm Hg, PaO2 of 70 mm Hg, and bicarbonate (HCO3--) of 26 mEq/L. What disorder is indicated by these findings?

respiratory alkalosis Respiratory alkalosis results from alveolar hyperventilation. It's marked by a decrease in PaCO2 to less than 35 mm Hg and an increase in blood pH over 7.45. Metabolic acidosis is marked by a decrease in HCO3-- to less than 22 mEq/L, and a decrease in blood pH to less than 7.35. In respiratory acidosis, the pH is less than 7.35 and the PaCO2 is greater than 45 mm Hg. In metabolic alkalosis, the HCO3-- is greater than 26 mEq/L and the pH is greater than 7.45.

A client has been diagnosed with metabolic alkalosis. The nurse should anticipate what finding from the client's arterial blood gases?

serum bicarbonate of 28 mEq/L Evaluation of arterial blood gases reveals a pH greater than 7.45 and a serum bicarbonate concentration greater than 26 mEq/L.

A client with a pulmonary embolus has the following arterial blood gas (ABG) values: pH, 7.49; partial pressure of arterial oxygen (PaO2), 60 mm Hg; partial pressure of arterial carbon dioxide (PaCO2), 30 mm Hg; bicarbonate (HCO3-) 25 mEq/L. What should the nurse do first?

Administer oxygen by nasal cannula as ordered. When a pulmonary embolus places a client at risk for oxygen deprivation, the body compensates by hyperventilating. This causes respiratory alkalosis, as reflected in the client's ABG values. However, the most significant ABG value is the PaO2 value of 60 mm Hg, which indicates hypoxemia. To manage hypoxemia, the nurse should increase oxygenation by administering oxygen via nasal cannula as ordered. Instructing the client to breathe into a paper bag would cause depressed oxygenation when the client reinhaled carbon dioxide. Auscultating breath sounds or encouraging deep breathing and coughing wouldn't improve oxygenation.

The nurse observes that a client with a history of panic attacks is hyperventilating. What action should the nurse take?

Have the client breathe into a paper bag. The best way to ease symptoms caused by hyperventilation is to have the client breathe into a paper bag. This helps to raise carbon dioxide level, which encourages deeper, slower breathing. The symptoms of hyperventilation will not be alleviated by having the client put the head between the knees, giving the client low concentrations of oxygen, or having the client take deep, slow breaths and exhaling normally.

A client has meconium-stained amniotic fluid. Fetal scalp sampling indicates a blood pH of 7.12; fetal bradycardia is present. Based on these findings, the nurse should take which action?

Prepare for cesarean birth. Fetal blood pH of 7.19 or lower signals severe fetal acidosis; meconium-stained amniotic fluid and bradycardia are further signs of fetal distress that warrant cesarean birth. Amnioinfusion is indicated when the only abnormal fetal finding is meconium-stained amniotic fluid. Client repositioning may improve uteroplacental perfusion, but only serves as a temporary measure because the risk of fetal asphyxia is imminent. Oxytocin administration increases contractions, exacerbating fetal stress.

The nurse on a surgical unit is caring for a client recovering from recent surgery with the placement of a nasogastric tube on low continuous suction. Which acid-base imbalance is most likely to occur?

metabolic alkalosis Metabolic alkalosis results in increased plasma pH because of an accumulated base bicarbonate or decreased hydrogen ion concentration. Factors that increase base bicarbonate include excessive oral or parenteral use of bicarbonate-containing drugs, a rapid decrease in extracellular fluid volume and loss of hydrogen and chloride ions as with gastric suctioning. Acidotic states are from excess carbonic acid and hydrogen ions in the system. Respiratory alkalosis results from a carbonic acid deficit that occurs when rapid breathing releases more CO2 than necessary.

A client has the following arterial blood gas values: pH, 7.52; PaO2, 50 mm Hg (6.7 kPa); PaCO2, 28 mm Hg (3.7 kPa); HCO3-, 24 mEq/L (24 mmol/l). The nurse determines that which of the following is a possible cause for these findings?

Pulmonary embolus. A PaCO2 of 28 mm Hg (3.7 kPa) and PaO2 of 50 mm Hg (6.7 kPa) are both abnormal; the PaO2 of 50 mm Hg (6.7 kPa) signifies acute respiratory failure. In evaluating possible causes for this disorder, the nurse should consider conditions that lead to hypoxia and hyperventilation, such as pulmonary embolus. COPD is typically associated with respiratory acidosis and elevated PaCO2. The client with diabetic ketoacidosis most often has metabolic acidosis. A myocardial infarction does not often cause an acid-base imbalance because the primary problem is cardiac in origin.

Oxygen at the rate of 2 liters per minute through nasal cannula is prescribed for a client with chronic obstructive pulmonary disease (COPD). Which of the following statements best describes why the oxygen therapy is maintained at a relatively low concentration?

The client's respiratory center is so used to high carbon dioxide and low oxygen levels that changing these levels may eliminate his stimulus for breathing. Relatively low concentrations of oxygen are administered to clients with COPD so as not to eliminate their respiratory drive. Carbon dioxide content in the blood normally regulates respirations. Clients with COPD, though, are often accustomed to high carbon dioxide levels; the low oxygen blood level is their stimulus to breathe. If they receive excessive oxygen and experience a drop in the blood carbon dioxide level, they may stop breathing. Oxygen flow rate is not diminished at high levels when administered through a nasal cannula. The client's ability to absorb oxygen administered at a higher level is not affected. Increased oxygen levels and decreased carbon dioxide levels cannot cause cells to burst.

A client is taking metformin. To prevent lactic acidosis resulting from use of this drug, the nurse should instruct the client to report which symptoms? Select all that apply.

hyperventilation dizziness muscle discomfort There is a high risk of lactic acidosis when using metformin; 50% of the cases may be fatal. A black box warning for metformin is to instruct the client to stop the drug and immediately notify the prescriber about unexplained hyperventilation, muscle pain, malaise, dizziness, light-headedness, unusual sleepiness, unexplained stomach pain, feelings of coldness, slow or irregular heart rate, or other nonspecific symptoms of early lactic acidosis. Headache, hunger, and tingling in the fingertips are not signs of lactic acidosis.