4335: Midterm, ABGs

Metabolic Acidosis can occur due to (Excess carbonic acid or base bicarbonate deficit caused by): 1. Ketoacidosis 2. Lactic acid accumulation (shock) 3. Severe diarrhea 4. Kidney disease 5. Nasogastric suctioning

1, 2, 3, 4 Excess Nasogastric suctioning may lead to metabolic alkalosis (lose acid from stomach)

ABG normal ranges for: 1. pH 2. PaCO2 3. HCO3

1. 7.35-7.45 2. 35-45 3. 22-26

In metabolic alkalosis, the blood pH level: A. Increases B. Decreases C. Stays the same

A

A patient is admitted with metabolic acidosis. Which system is not functioning normally? A. Renal system B. Buffer system C. Endocrine system D. Respiratory system

A. When the patient has metabolic acidosis, the kidneys are not combining H+ with ammonia to form ammonium or eliminating acid with secretion of free hydrogen into the renal tubule. The buffer system neutralizes HCl acid by forming a weak acid. The hormone system is not directly related to acid-base balance. The respiratory system releases CO2 that combines with water to form hydrogen ions and bicarbonate. The hydrogen is then buffered by the hemoglobin.

Interpret the following ABGs: pH: 7.79; CO2: 24; HCO3: 21

ABG Interpretation: Partially Compensated respiratory alkalosis

pH: 7.15; CO2: 33; HCO3: 20

ABG Interpretation: Partially compensated metabolic acidosis

ph: 7.17; CO2: 35; HCO3: 12

ABG Interpretation: Uncompensated Metabolic Acidosis

pH: 7.40; CO2: 40; HCO3: 25

ABG interpretation: Normal

A patient is admitted to the hospital with severe dyspnea and wheezing. Arterial blood gas levels on admission are pH 7.26; PaCO2, 55 mm Hg; PaO2, 68 mm Hg; and HCO3 - , 24. How does the nurse interpret these laboratory values? 1. Metabolic acidosis 2. Metabolic alkalosis 3. Respiratory acidosis 4. Respiratory alkalosis

Answer: 3. The pH is abnormally low, which indicates acidosis. The PaCO2 is high, which indicates respiratory acidosis. The HCO3 - is in the normal range, which indicates an acute respiratory acidosis that has not had time for renal compensation (Uncompensated). The low PaO2 and the severe dyspnea and wheezing are consistent with this interpretation.

Which two organs are responsible for acid excretion, which helps maintain acid-base balance? A. Lungs and kidneys B. Kidneys and liver C. Bladder and bowel D. Lungs and bladder

Answer: A Rationale: The lungs excrete carbonic acid. The kidneys excrete metabolic acids.

A student studies the difference between metabolic acidosis and alkalosis. They know that what state increases blood HCO-3.

Answer: Metabolic alkalosis Rationale: Metabolic alkalosis occurs from a direct increase of base HCO-3 or a decrease of metabolic acid, which increases blood HCO-3 by releasing it from its buffering function.

A patient has the following arterial blood gases: HCO3 38, pH 7.50, PaCO2 50. Which of the following signs may this patient exhibit as a compensatory mechanism? A. Hyperventilation (tachypnea) B. Hypoventilation (bradypnea) C. Increased potassium level (hyperkalemia) D. Constipation

B

What of the following is NOT a cause of metabolic alkalosis? A. Hyperaldosteronism B. Usage of Diamox C. Nasogastric suctioning D. Diuretic therapy

B Diamox (Acetazolamide) is an inhibitor of carbonic anhydrase that stimulates the respiratory centre by creating a mild metabolic acidosis. You can figure out the answer to this Q by eliminating all other answers (A, C, D all cause metabolic alkalosis)

You are caring for a patient admitted with a diagnosis of chronic obstructive pulmonary disease (COPD) who has the following arterial blood gas results: pH 7.33, PaO2 47 mm Hg, PaCO2 60 mm Hg, HCO3 32 mEq/L, and O2 saturation of 92%. What is the correct interpretation of these results? A. Fully compensated respiratory alkalosis B. Partially compensated respiratory acidosis C. Normal acid-base balance with hypoxemia D. Normal acid-base balance with hypercapnia

B. A low pH (normal, 7.35 to 7.45) indicates acidosis. In a patient with respiratory disease such as COPD, the patient retains carbon dioxide (normal, 35 to 45 mm Hg), which acts as an acid in the body. For this reason, the patient has respiratory acidosis. The elevated HCO3 indicates a partial compensation for the elevated CO2.

You are admitting a patient who reports abdominal pain, nausea, and vomiting. A proximal bowel obstruction is suspected. Which acid-base imbalance do you anticipate in this patient? A. Metabolic acidosis B. Metabolic alkalosis C. Respiratory acidosis D. Respiratory alkalosis

B. Because gastric secretions are rich in HCl acid, the patient who is vomiting will lose a significant amount of gastric acid and be at an increased risk for metabolic alkalosis.

A mother is admitted to the emergency department following complaints of fever and chills. The nurse on duty took her vital signs and noted the following: Temp = 100 °F; apical pulse = 95; respiration = 20 and deep. Measurement of arterial blood gas shows pH 7.37, PaO2 90 mm Hg, PaCO2 40 mm Hg, and HCO3 24 mmol/L. What is your assessment? A. Hyperthermia B. Hyperthermia and Respiratory Alkalosis C. Hypothermia D. Hypothermia and Respiratory Alkalosis

Correct Answer: A. Hyperthermia An individual is considered to have hyperthermia if he or she has a temperature of >37.5 or 38.3 °C (99.5 or 100.9 °F). The measurement of arterial blood gases are normal.

A cigarette vendor was brought to the emergency department of a hospital after she fell into the ground and hurt her left leg. She is noted to be tachycardic and tachypneic. Painkillers were carried out to lessen her pain. Suddenly, she started complaining that she is still in pain and now experiencing muscle cramps, tingling, and paraesthesia. Measurement of arterial blood gas reveals pH 7.6, PaO2 120 mm Hg, PaCO2 31 mm Hg, and HCO3 25 mmol/L. What does this mean? A. Respiratory Alkalosis, Uncompensated B. Respiratory Acidosis, Partially Compensated C. Metabolic Alkalosis, Uncompensated D. Metabolic Alkalosis, Partially Compensated

Correct Answer: A. Respiratory Alkalosis, Uncompensated The primary disorder is acute respiratory alkalosis (low CO2) due to the pain and anxiety causing her to hyperventilate. There has not been time for metabolic compensation.

Mr. Wales, who underwent post-abdominal surgery, has a nasogastric tube. The nurse on duty notes that the nasogastric tube (NGT) is draining a large amount (900 cc in 2 hours) of coffee ground secretions. The client is not oriented to person, place, or time. The nurse contacts the attending physician and STAT ABGs are ordered. The results from the ABGs show pH 7.57, PaCO2 37 mmHg and HCO3 30 mEq/L. What is your assessment? A. Metabolic Acidosis, Uncompensated B. Metabolic Alkalosis, Uncompensated C. Respiratory Alkalosis, Uncompensated D. Metabolic Alkalosis, Partially Compensated

Correct Answer: B. Metabolic Alkalosis, Uncompensated The postoperative client's ABG results show that he has metabolic alkalosis because of an increased pH and HCO3. It is uncompensated due to the normal PaCO2 which is within 35 to 45 mmHg

George Kent is a 54-year-old widower with a history of chronic obstructive pulmonary disease and was rushed to the emergency department with increasing shortness of breath, pyrexia, and a productive cough with yellow-green sputum. He has difficulty communicating because of his inability to complete a sentence. One of his sons, Jacob, says he has been unwell for three days. Upon examination, crackles and wheezes can be heard in the lower lobes; he has tachycardia and a bounding pulse. Measurement of arterial blood gas shows pH 7.3, PaCO2 68 mm Hg, HCO3 28 mmol/L, and PaO2 60 mm Hg. How would you interpret this? A. Respiratory Acidosis, Uncompensated B. Respiratory Acidosis, Partially Compensated C. Metabolic Alkalosis, Uncompensated D. Metabolic Acidosis, Partially Compensated

Correct Answer: B. Respiratory Acidosis, Partially Compensated The patient has respiratory acidosis (raised carbon dioxide) resulting from an acute exacerbation of chronic obstructive pulmonary disease, with partial compensation.

Mrs. Johansson, who had undergone surgery in the post-anesthesia care unit (PACU), is difficult to arouse two hours following surgery. Nurse Florence in the PACU has been administering Morphine Sulfate intravenously to the client for complaints of post-surgical pain. The client's respiratory rate is 7 per minute and demonstrates shallow breathing. The patient does not respond to any stimuli. The nurse assesses the ABCs (remember Airway, Breathing, Circulation!) and obtains ABGs STAT! Measurement of arterial blood gas shows pH 7.10, PaCO2 70 mm Hg, and HCO3 24 mEq/L. What does this mean? A. Respiratory Alkalosis, Partially Compensated B. Respiratory Acidosis, Uncompensated C. Metabolic Alkalosis, Partially Compensated D. Metabolic Acidosis, Uncompensated

Correct Answer: B. Respiratory Acidosis, Uncompensated The results show that Mrs. Johansson has respiratory acidosis because of decreased pH and increased PaCO2 which means acidic in nature. Meanwhile, it is uncompensated because HCO3 is within the normal range.

A mountaineer attempts an assault on a high mountain in the Andes and reaches an altitude of 5000 meters (16,400 ft) above sea level. What will happen to his arterial PCO2 and pH? A. Both will be lower than normal. B. The pH will rise and PCO2 will fall. C. Both will be higher than normal due to physical exertion. D. The pH will fall and PCO2 will rise

Correct Answer: B. The pH will rise and PCO2 will fall. The mountaineer will suffer from a respiratory alkalosis. The decline in the PO2 with altitude will stimulate breathing to offset the hypoxia. Carbon dioxide is driven from the blood faster than it is produced in the tissues so PCO2 falls and pH rises.

Baby Angela was rushed to the Emergency Room following her mother's complaint that the infant has been irritable, difficult to breastfeed, and has had diarrhea for the past 3 days. The infant's respiratory rate is elevated and the fontanels are sunken. The Emergency Room physician orders ABGs after assessing the ABCs. The results from the ABG results show pH 7.39, PaCO2 27 mmHg, and HCO3 19 mEq/L. What does this mean? A. Respiratory Alkalosis, Fully Compensated B. Metabolic Acidosis, Uncompensated C. Metabolic Acidosis, Fully Compensated D. Respiratory Acidosis, Uncompensated

Correct Answer: C. Metabolic Acidosis, Fully Compensated Baby Angela has metabolic acidosis due to decreased HCO3 and slightly acidic pH. Her pH value is within the normal range which made the result fully compensated.

Ricky's grandmother has been suffering from persistent vomiting for two days now. She appears to be lethargic and weak and has myalgia. She is noted to have dry mucus membranes and her capillary refill takes >4 seconds. She is diagnosed as having gastroenteritis and dehydration. Measurement of arterial blood gas shows pH 7.5, PaO2 85 mm Hg, PaCO2 40 mm Hg, and HCO3 34 mmol/L. What acid-base disorder is shown? A. Respiratory Alkalosis, Uncompensated B. Respiratory Acidosis, Partially Compensated C. Metabolic Alkalosis, Uncompensated D. Metabolic Alkalosis, Partially Compensated

Correct Answer: C. Metabolic Alkalosis, Uncompensated The primary disorder is uncompensated metabolic alkalosis (high HCO3 -). As CO2 is the strongest driver of respiration, it generally will not allow hypoventilation as compensation for metabolic alkalosis.

A young woman is found comatose, having taken an unknown number of sleeping pills an unknown time before. An arterial blood sample yields the following values: pH 6.90, HCO3- 13 meq/liter, and PaCO2 68 mmHg. This patient's acid-base status is most accurately described as: A. Metabolic Acidosis B. Respiratory Acidosis C. Simultaneous Respiratory and Metabolic Acidosis D. Respiratory Acidosis with Complete Renal Compensation

Correct Answer: C. Simultaneous Respiratory and Metabolic Acidosis Whenever the PCO2 and HCO3 are abnormal in opposite directions, ie, one above normal while the other is reduced, a mixed respiratory and metabolic acid-base disorder exists. When the PCO2 is elevated and the [HCO3-] reduced, respiratory acidosis and metabolic acidosis coexist.

Carl, an elementary student, was rushed to the hospital due to vomiting and a decreased level of consciousness. The patient displays slow and deep (Kussmaul breathing), and he is lethargic and irritable in response to stimulation. He appears to be dehydrated—his eyes are sunken and mucous membranes are dry—and he has a two-week history of polydipsia, polyuria, and weight loss. Measurement of arterial blood gas shows pH 7.0, PaO2 90 mm Hg, PaCO2 23 mm Hg, and HCO3 12 mmol/L; other results are Na+ 126 mmol/L, K+ 5 mmol/L, and Cl- 95 mmol/L. What is your assessment? A. Respiratory Acidosis, Uncompensated B. Respiratory Acidosis, Partially Compensated C. Metabolic Alkalosis, Uncompensated D. Metabolic Acidosis, Partially, Compensated

Correct Answer: D. Metabolic Acidosis, Partially, Compensated The student was diagnosed with diabetes mellitus. The results show that he has metabolic acidosis (low HCO3 -) with respiratory compensation (low CO2).

In a patient undergoing surgery, it was vital to aspirate the contents of the upper gastrointestinal tract. After the operation, the following values were acquired from an arterial blood sample: pH 7.55, PCO2 52 mm Hg and HCO3- 40 mmol/l. What is the underlying disorder? A. Respiratory Acidosis B. Respiratory Alkalosis C. Metabolic Acidosis D. Metabolic Alkalosis

Correct Answer: D. Metabolic Alkalosis NGT suctioning, vomiting, hypokalemia and overdosage of NaHCO3 are considered risk factors of metabolic alkalosis.

A patient is in metabolic alkalosis due to diuretic therapy. How do you expect the potassium level and bicarbonate level to be affected? A. Increased potassium level and increased bicarb level B. Decreased potassium level and decreased bicarb level C. Increased potassium level and decreased bicarb level D. Decreased potassium level and increase bicarb level

D

The nurse on a medical-surgical unit identifies which patient as having the highest risk for metabolic alkalosis? A. A patient with a traumatic brain injury B. A patient with type 1 diabetes mellitus C. A patient with acute respiratory failure D. A patient with nasogastric tube suction

D. Excessive nasogastric suctioning may cause metabolic alkalosis. Brain injury may cause hyperventilation and respiratory alkalosis. Type 1 diabetes mellitus (diabetic ketoacidosis) is associated with metabolic acidosis. Acute respiratory failure may lead to respiratory acidosis.

You are caring for a patient admitted with an exacerbation of asthma. After several treatments, the ABG results are pH 7.40, PaCO2 40 mm Hg, HCO3 24 mEq/L, PaO2 92 mm Hg, and O2 saturation of 99%. You interpret these results as: A. metabolic acidosis. B. respiratory acidosis. C. respiratory alkalosis. D. within normal limits

D. The normal pH is 7.35 to 7.45. Normal PaCO2 levels are 35 to 45 mm Hg, and HCO3 is 22 to 26 mEq/L. Normal PaO2 is greater than 80 mm Hg. Normal oxygen saturation is greater than 95%. Because the patient's results all fall within these normal ranges, the nurse can conclude that the patient's blood gas results are within normal limits.

pH: 7.42; CO2: 40; HCO3: 27

Fully Compensated metabolic alkalosis

PaCO2: 46, HCO3: 27, pH: 7.36

Fully compensated respiratory acidosis

What is your interpretation of Jeri's ABGs? pH: 7.28; PaCO2: 50; HCO3-: 30; PaO2: 75

Partially Compensated Respiratory Acidosis

PaCO2: 49, HCO3: 28, pH: 7.30

Partially compensated respiratory acidosis

Jeri is a 22-year-old female who has been on a 3-day party binge. Her friends bring her to the ED after being unable to awaken her. Assessment reveals shallow respirations with a rate of 8/min, diminished breath sounds, and decreased level of consciousness. What type of acid-base imbalance would you expect Jeri to have?

Respiratoy Acidosis. CNS depression is a sign of acidosis. Decreased respirations means the body is retaining CO2 (less breathing out, more retaining acid)

A patient reports taking Diamox (which is a drug that causes metabolic acidosis) and has been reporting confusion, fatigue, and headaches. On assessment, you note the patient is exhibiting deep and rapid respirations. Which arterial blood gas finding below confirms the acid-base imbalance for this patient given their symptoms and medication usage? A. HCO3 12, pH 7.19, PaCO2 29 B. HCO3 23, pH 7.36, PaCO2 36 C. HCO3 10, pH 7.65, PaCO2 47 D. PaCO2 49, pH 7.55, HCO3 21

The answer is A 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 states they have been vomiting for the last 4 days. The patient is irritable, weak, and reporting muscle cramping and weakness. On assessment, the patient is experiencing bradypnea with a respiratory rate of 10. The patient has the following ABGs result: HCO3 36, pH 7.52, PaCO2 48. Which condition below is presenting? A. Metabolic alkalosis partially compensated B. Metabolic alkalosis fully compensated C. Metabolic acidosis partially compensated D. Metabolic acidosis not compensated

The answer is A: Metabolic alkalosis partially compensated

A patient has the following arterial blood gases: PaCO2 33, HCO3 15, pH 7.23. Which condition below is presenting? A. Metabolic alkalosis partially compensated B. Metabolic acidosis partially compensated C. Respiratory alkalosis not compensated D. Metabolic acidosis fully compensated

The answer is B: Metabolic acidosis partially compensated

Which of the following is NOT a cause of metabolic acidosis? A. Aspirin toxicity B. Ileostomy C. Hyperaldosteronism D. Carbonic anhydrase inhibitors

The answer is C: Hyperaldosteronism causes metabolic ALKalosis

T/F: Hyperventilation is a compensatory mechanism for metabolic acidosis.

True. In the case of metabolic acidosis, which is an elevated bicarbonate state, hyperventilation will 'blow off' carbon dioxide, and thus acts as a buffer to partially or totally compensate for this acidotic state.

PaCO2: 35, HCO3: 13, pH: 7.15

Uncompensated metabolic acidosis