NSG 535 DIAGNOSTICS EXAM #2 | COMPREHENSIVE DIAGNOSTICS
NURSING STUDY GUIDE, PRACTICE QUESTIONS & ANSWERS
2026/2027
State normal values for pH, pCO2, HCO3, and PaO2 - correct answer ✔✔pH 7.35-7.45, pCO2 35-45
mmHg, HCO3 22-26 mEqs/L, and PaO2 70-100 mmHg
Normal arterial pH vs venous pH - correct answer ✔✔Venous blood is slightly more acidic since it
contains higher amounts of dissolved carbon dioxide (normal = 7.35). Normal arterial pH = 7.4.
PaO2 vs SaO2 - correct answer ✔✔PaO2 is the partial pressure of oxygen dissolved in the plasma.
Determines the amount of oxygen that can bind with hemoglobin. This is NOT indicative of total oxygen
content. SaO2 is the % of oxygen in the blood that is bound to hemoglobin.
Base excess (BE) - correct answer ✔✔Amount of acid or base that must be added to return 1L of whole
blood pH to 7.40 and PaCO2 to 40 mmHg. Normal range is -2 to +2. Normal balance = 0. BE < zero (base
deficit) suggests metabolic acidosis, while a BE > zero suggests metabolic alkalosis.
Chloride shift - correct answer ✔✔Occurs when movement of CO2 into a deoxygenated RBC results in
the exchange of bicarb out of the cell and Cl- into the cell (the reverse happens in the lungs). These
actions within the hemoglobin buffer system mitigate changes in pH and maintain RBCs' electrical
neutrality.
Extracellular compartment buffers - correct answer ✔✔Bone demineralization (to release alkaline
compounds in response to acidosis), and ion exchanges (extracellular H+ is exchanged for either Na+ and
Ca2+, or intracellular K+).
Adverse effects of acidemia - correct answer ✔✔Tissue hypoxia (despite rightward shift on the
oxyhemoglobin dissociation curve), decreased responsiveness to endogenous and exogenous
catecholamines, decreased threshold for v-fib, progressive hyperkalemia (K+ is exchanged for
extracellular H+), and CNS depression/CO2 narcosis secondary to intracranial hypertension.
Anion gap - correct answer ✔✔The difference between the major cations and major anions that equals
the concentration of unmeasured anions in the serum. Useful in diagnosing a cause for the acidosis.
Normal range = 7-14 mEq/L.
Anion gap equation - correct answer ✔✔[Na+] - ([Cl-] + [HCO3-])
In high anion gap acidosis, the bicarbonate concentration ________ in response to the need to buffer
the increased acids. The high anion gap results when bicarbonate is replaced by _________ . - correct
answer ✔✔decreases; unmeasured anions (anion gap > 14 means that the root cause of acidosis is that
there's not enough bicarb to buffer the acid)
, Normal anion gap acidosis is characterized by ________ . - correct answer ✔✔hyperchloremia; plasma
Cl- increases to take the place of lost HCO3- ions to maintain electrical neutrality.
Causes of high anion gap acidosis - correct answer ✔✔Renal failure, lactic acidosis, hypoxemia,
ketoacidosis, absolute/relative lack of insulin, inborn errors of metabolism, ingestion of exogenous
nonvolatile acids (salicylate, methanol, sulfur, ethylene glycol, paraldehyde, toluene, etc.), and
rhabdomyolysis.
Causes of normal anion gap acidosis - correct answer ✔✔Increased GI losses of HCO3- (diarrhea,
ingestion of calcium or magnesium chloride, fistulas, ileus), increased general losses of HCO3- (carbonic
anhydrase inhibitors, renal tubular acidosis, hypoaldosteronism) and other causes (rapid expansion of
fluid volume with NaCl, TPN, fluids with Cl-).
Adverse effects of alkalosis - correct answer ✔✔Hypokalemia, decreased ionized calcium that leads to
circulatory depression and neuromuscular irritability, reduced cerebral blood flow, increased SVR,
coronary vasospasm, increased bronchial smooth muscle tone, decreased pulmonary vascular
resistance, decreased metabolic production of CO2
Chloride-sensitive metabolic alkalosis - correct answer ✔✔Due to a loss of NaCl and extracellular fluid
depletion (i.e. vomiting, NG suction, diuretic). Can be corrected with NaCl- or KCl- administration.
Characterized by low urine chloride (< 10 mEq/L).
Chloride-resistant metabolic alkalosis - correct answer ✔✔Due to increased mineralocorticoid activity
(hyperaldosteronism) or severe magnesium or potassium deficiency. Does not correct with NaCl, usually
treated with aldosterone antagonist like spironolactone. Characterized by elevated urine chloride (> 20
mEq/L).
Causes of metabolic alkalosis - correct answer ✔✔Loss of H+ from extracellular space (vomiting/NG
suction, excess mineralocorticoids, diuretics, gastric fistulas), massive blood transfusion, severe
hypokalemia (hyperaldosteronism, Cushing's, laxative abuse), ingestion of excess HCO3- (oral/parenteral
HCO3-, antacids, NaHCO3- dialysis).
Family health history - correct answer ✔✔Includes assessment of genetic conditions in first-, second-,
and third-degree relatives. Individual's level of risk is average, moderate, or high depending on the
history.
2 criteria for "average risk" associated with a specific genetic condition - correct answer ✔✔No known
family history OR only one second-degree (or more distant) family member affected
2 criteria for "moderate risk" associated with a specific genetic condition - correct answer ✔✔One first-
degree relative with disease onset at an average age OR two affected second-degree relatives on the
same side of the family.
5 criteria for "high risk" associated with a specific genetic condition - correct answer ✔✔Premature
disease or unusual presentation in a first-degree relative OR two or more first-degree relatives on the
same side of the family OR two or more second-degree relatives on the same side of the family, with at
least one having premature onset OR three or more affected on the same side of the family OR
moderate-risk status on both sides of the family
NURSING STUDY GUIDE, PRACTICE QUESTIONS & ANSWERS
2026/2027
State normal values for pH, pCO2, HCO3, and PaO2 - correct answer ✔✔pH 7.35-7.45, pCO2 35-45
mmHg, HCO3 22-26 mEqs/L, and PaO2 70-100 mmHg
Normal arterial pH vs venous pH - correct answer ✔✔Venous blood is slightly more acidic since it
contains higher amounts of dissolved carbon dioxide (normal = 7.35). Normal arterial pH = 7.4.
PaO2 vs SaO2 - correct answer ✔✔PaO2 is the partial pressure of oxygen dissolved in the plasma.
Determines the amount of oxygen that can bind with hemoglobin. This is NOT indicative of total oxygen
content. SaO2 is the % of oxygen in the blood that is bound to hemoglobin.
Base excess (BE) - correct answer ✔✔Amount of acid or base that must be added to return 1L of whole
blood pH to 7.40 and PaCO2 to 40 mmHg. Normal range is -2 to +2. Normal balance = 0. BE < zero (base
deficit) suggests metabolic acidosis, while a BE > zero suggests metabolic alkalosis.
Chloride shift - correct answer ✔✔Occurs when movement of CO2 into a deoxygenated RBC results in
the exchange of bicarb out of the cell and Cl- into the cell (the reverse happens in the lungs). These
actions within the hemoglobin buffer system mitigate changes in pH and maintain RBCs' electrical
neutrality.
Extracellular compartment buffers - correct answer ✔✔Bone demineralization (to release alkaline
compounds in response to acidosis), and ion exchanges (extracellular H+ is exchanged for either Na+ and
Ca2+, or intracellular K+).
Adverse effects of acidemia - correct answer ✔✔Tissue hypoxia (despite rightward shift on the
oxyhemoglobin dissociation curve), decreased responsiveness to endogenous and exogenous
catecholamines, decreased threshold for v-fib, progressive hyperkalemia (K+ is exchanged for
extracellular H+), and CNS depression/CO2 narcosis secondary to intracranial hypertension.
Anion gap - correct answer ✔✔The difference between the major cations and major anions that equals
the concentration of unmeasured anions in the serum. Useful in diagnosing a cause for the acidosis.
Normal range = 7-14 mEq/L.
Anion gap equation - correct answer ✔✔[Na+] - ([Cl-] + [HCO3-])
In high anion gap acidosis, the bicarbonate concentration ________ in response to the need to buffer
the increased acids. The high anion gap results when bicarbonate is replaced by _________ . - correct
answer ✔✔decreases; unmeasured anions (anion gap > 14 means that the root cause of acidosis is that
there's not enough bicarb to buffer the acid)
, Normal anion gap acidosis is characterized by ________ . - correct answer ✔✔hyperchloremia; plasma
Cl- increases to take the place of lost HCO3- ions to maintain electrical neutrality.
Causes of high anion gap acidosis - correct answer ✔✔Renal failure, lactic acidosis, hypoxemia,
ketoacidosis, absolute/relative lack of insulin, inborn errors of metabolism, ingestion of exogenous
nonvolatile acids (salicylate, methanol, sulfur, ethylene glycol, paraldehyde, toluene, etc.), and
rhabdomyolysis.
Causes of normal anion gap acidosis - correct answer ✔✔Increased GI losses of HCO3- (diarrhea,
ingestion of calcium or magnesium chloride, fistulas, ileus), increased general losses of HCO3- (carbonic
anhydrase inhibitors, renal tubular acidosis, hypoaldosteronism) and other causes (rapid expansion of
fluid volume with NaCl, TPN, fluids with Cl-).
Adverse effects of alkalosis - correct answer ✔✔Hypokalemia, decreased ionized calcium that leads to
circulatory depression and neuromuscular irritability, reduced cerebral blood flow, increased SVR,
coronary vasospasm, increased bronchial smooth muscle tone, decreased pulmonary vascular
resistance, decreased metabolic production of CO2
Chloride-sensitive metabolic alkalosis - correct answer ✔✔Due to a loss of NaCl and extracellular fluid
depletion (i.e. vomiting, NG suction, diuretic). Can be corrected with NaCl- or KCl- administration.
Characterized by low urine chloride (< 10 mEq/L).
Chloride-resistant metabolic alkalosis - correct answer ✔✔Due to increased mineralocorticoid activity
(hyperaldosteronism) or severe magnesium or potassium deficiency. Does not correct with NaCl, usually
treated with aldosterone antagonist like spironolactone. Characterized by elevated urine chloride (> 20
mEq/L).
Causes of metabolic alkalosis - correct answer ✔✔Loss of H+ from extracellular space (vomiting/NG
suction, excess mineralocorticoids, diuretics, gastric fistulas), massive blood transfusion, severe
hypokalemia (hyperaldosteronism, Cushing's, laxative abuse), ingestion of excess HCO3- (oral/parenteral
HCO3-, antacids, NaHCO3- dialysis).
Family health history - correct answer ✔✔Includes assessment of genetic conditions in first-, second-,
and third-degree relatives. Individual's level of risk is average, moderate, or high depending on the
history.
2 criteria for "average risk" associated with a specific genetic condition - correct answer ✔✔No known
family history OR only one second-degree (or more distant) family member affected
2 criteria for "moderate risk" associated with a specific genetic condition - correct answer ✔✔One first-
degree relative with disease onset at an average age OR two affected second-degree relatives on the
same side of the family.
5 criteria for "high risk" associated with a specific genetic condition - correct answer ✔✔Premature
disease or unusual presentation in a first-degree relative OR two or more first-degree relatives on the
same side of the family OR two or more second-degree relatives on the same side of the family, with at
least one having premature onset OR three or more affected on the same side of the family OR
moderate-risk status on both sides of the family
