NLE Foundations of Medical-Surgical Nursing — Fluid, Electrolyte and Acid-Base ImbalancesExam Answer Templates

Marks

1

Topic

Electrolyte Normal Values

Difficulty

easy

Template Id

T1

Examiner Tip

For any 'normal value' question, always include the unit. A value without a unit is clinically meaningless and will not earn the mark.

Model Answer

The normal serum potassium level is 3.5 to 5.0 mEq/L.

Question Type

very_short_answer

Answer Structure

• State the electrolyte name and its normal range with correct unit [1 mark]

Scoring Breakdown

Common Mark Deductions

• Writing incorrect unit (e.g., mg/dL instead of mEq/L)
• Stating only the lower or upper limit rather than the full range
• Reversing the numbers (e.g., 5.0–3.5)

Key Phrases To Include

• 3.5–5.0 mEq/L
• mEq/L

Marks

1

Topic

ABG Interpretation — ROME Mnemonic

Difficulty

easy

Template Id

T2

Examiner Tip

Even in a 1-mark question, briefly state what 'opposite' and 'equal' refer to. Examiners want to see that you can apply the mnemonic, not just recite it.

Model Answer

ROME stands for: Respiratory Opposite — in respiratory disorders, pH and PaCO₂ move in opposite directions; Metabolic Equal — in metabolic disorders, pH and HCO₃⁻ move in the same direction.

Question Type

very_short_answer

Answer Structure

• Define R and O component (Respiratory Opposite) [0.5 mark]
• Define M and E component (Metabolic Equal) [0.5 mark]

Scoring Breakdown

Common Mark Deductions

• Reversing the meanings (writing 'Respiratory Equal, Metabolic Opposite')
• Not specifying which values move in which direction
• Simply listing words without explanation

Key Phrases To Include

• Respiratory Opposite
• Metabolic Equal
• pH and PaCO₂ move in opposite directions
• pH and HCO₃⁻ move in the same direction

Marks

1

Topic

Hypokalemia — Nursing Management

Difficulty

easy

Template Id

T3

Examiner Tip

The phrase 'never IV push' is a classic NLE high-yield point. If the question is about potassium administration, always include this phrase — it is the single most important safety point.

Model Answer

The priority nursing action is to verify that the patient has adequate urine output of at least 30 mL/hr before administration, and to ensure IV KCl is always diluted — never administered by IV push — at a rate not exceeding 10 mEq/hr on a general unit.

Question Type

very_short_answer

Answer Structure

• State the safety check (urine output) and the critical safety rule (never IV push, dilute, rate limit) [1 mark]

Scoring Breakdown

Common Mark Deductions

• Writing only 'administer as ordered' without any specific safety consideration
• Stating the drug name without the safety precaution
• Confusing potassium with calcium gluconate administration

Key Phrases To Include

• never IV push
• dilute
• urine output at least 30 mL/hr
• 10 mEq/hr
• cardiac arrest

Marks

2

Topic

Sodium Imbalances

Difficulty

easy

Template Id

T4

Examiner Tip

Differentiation questions are worth 1 mark per item being differentiated. Always use parallel structure — define both, give one sign each. The brief pathophysiologic link (cellular swelling vs. dehydration) elevates a 1-mark answer into a 2-mark answer.

Model Answer

Hyponatremia is defined as serum sodium below 135 mEq/L. It causes cellular swelling leading to neurologic manifestations such as confusion, headache, and seizures. Hypernatremia is defined as serum sodium above 145 mEq/L. It causes cellular dehydration (shrinkage), manifesting as thirst, restlessness, and dry mucous membranes.

Question Type

short_answer

Answer Structure

• Line 1: Define hyponatremia with serum value and state one manifestation with pathophysiologic rationale [1 mark]
• Line 2: Define hypernatremia with serum value and state one manifestation with pathophysiologic rationale [1 mark]

Scoring Breakdown

Common Mark Deductions

• Confusing the values (e.g., stating hyponatremia as Na⁺ above 145 mEq/L)
• Listing manifestations without linking them to the underlying pathophysiology
• Using only one value instead of both cutoffs

Key Phrases To Include

• below 135 mEq/L
• above 145 mEq/L
• cellular swelling
• cellular dehydration
• neurologic manifestations
• thirst

Marks

2

Topic

ABG Interpretation

Difficulty

medium

Template Id

T5

Examiner Tip

Always write your ABG interpretation as numbered steps. Examiners follow the same stepwise approach and award partial credit for each correct step — even if your final label is wrong, you can earn 1 out of 2 marks for correct partial reasoning.

Model Answer

Step 1 — pH: 7.28 is below 7.35, indicating acidosis. Step 2 — PaCO₂: 50 mmHg is above 45 mmHg (elevated). Using ROME — Respiratory Opposite: pH is low and PaCO₂ is high (they moved in opposite directions), confirming a respiratory cause. Step 3 — HCO₃⁻: 24 mEq/L is within normal range (22–26 mEq/L), indicating no metabolic compensation yet. Interpretation: Uncompensated Respiratory Acidosis.

Question Type

short_answer

Answer Structure

• Step 1: Identify pH as acidosis or alkalosis [0.5 mark]
• Step 2: Identify the primary cause as respiratory using PaCO₂ and ROME [1 mark]
• Step 3: Determine compensation status using HCO₃⁻ [0.5 mark]

Scoring Breakdown

Common Mark Deductions

• Identifying the correct disorder but omitting the compensation status
• Not showing the step-by-step reasoning (just writing the answer without working)
• Confusing PaCO₂ as the metabolic component and HCO₃⁻ as the respiratory component

Key Phrases To Include

• pH 7.28 — acidosis
• PaCO₂ 50 mmHg — elevated
• ROME — Respiratory Opposite
• HCO₃⁻ normal — uncompensated
• Uncompensated Respiratory Acidosis

Marks

2

Topic

Hyperkalemia — Cardiac Manifestations

Difficulty

medium

Template Id

T6

Examiner Tip

Examiners distinguish between students who memorize and students who understand. Pairing the ECG finding with 'this signals risk for...' shows understanding and earns both marks reliably.

Model Answer

1. Tall, peaked (tented) T waves — this reflects accelerated ventricular repolarization due to elevated serum potassium altering the cardiac cell resting membrane potential, signaling risk for fatal dysrhythmias. 2. Widened QRS complex — indicates slowed ventricular conduction, which can progress to ventricular fibrillation or asystole if potassium levels are not corrected promptly.

Question Type

short_answer

Answer Structure

• ECG finding 1 with clinical significance [1 mark]
• ECG finding 2 with clinical significance [1 mark]

Scoring Breakdown

Common Mark Deductions

• Describing ECG changes of hypokalemia (flattened T waves, U waves) instead of hyperkalemia
• Naming ECG changes without explaining their clinical significance
• Confusing peaked T waves as a sign of hypokalemia

Key Phrases To Include

• tall peaked T waves
• widened QRS
• ventricular fibrillation
• asystole
• cardiac dysrhythmia
• hyperkalemia

Marks

3

Topic

Fluid Volume Deficit — Nursing Management

Difficulty

medium

Template Id

T7

Examiner Tip

A 3-mark question requires a mini-essay structure: definition → assessment → interventions → outcome. Examiners reward answers that follow the nursing process sequence and include at least one specific value (e.g., urine output ≥30 mL/hr, 1 kg = 1 L).

Model Answer

Fluid Volume Deficit (FVD) or hypovolemia is the loss of ECF volume, commonly from vomiting, diarrhea, or hemorrhage. In the Philippine setting, acute gastroenteritis (AGE) is a frequent cause. Priority Assessment: Monitor vital signs for rapid, weak pulse and orthostatic hypotension. Assess level of consciousness, skin turgor, mucous membrane moisture, and urine output (oliguria is defined as less than 30 mL/hr). Priority Nursing Diagnosis (NANDA): Deficient Fluid Volume related to active fluid loss as evidenced by tachycardia, decreased urine output, and poor skin turgor. Priority Interventions (in order of urgency): 1. Restore circulating volume — administer isotonic IV fluids (0.9% NaCl or Lactated Ringer's) as ordered to prevent progression to hypovolemic shock. 2. Strict intake and output monitoring; weigh the patient daily (1 kg weight change ≈ 1 L fluid change). 3. Institute fall precautions due to orthostatic hypotension. 4. Encourage oral rehydration (ORS) when tolerated and safe. Expected Outcome: Patient's vital signs stabilize, urine output is maintained at ≥30 mL/hr, and signs of dehydration resolve.

Question Type

short_answer

Answer Structure

• Brief definition with local Philippine context (1–2 sentences) [0.5 mark]
• Priority assessment findings (pulse, BP, urine output, skin turgor) [0.5 mark]
• Priority NANDA nursing diagnosis [0.5 mark]
• At least 3 prioritized nursing interventions with rationale [1 mark]
• Expected patient outcome [0.5 mark]

Scoring Breakdown

Common Mark Deductions

• Not specifying the type of IV fluid (writing only 'give IV fluids')
• Omitting the urine output threshold of 30 mL/hr
• Not including fall precautions despite mentioning orthostatic hypotension
• Writing nursing interventions without any rationale

Key Phrases To Include

• ECF volume loss
• isotonic IV fluids
• 0.9% NaCl or Lactated Ringer's
• urine output ≥30 mL/hr
• orthostatic hypotension
• Deficient Fluid Volume (NANDA)
• 1 kg = 1 L
• fall precautions

Marks

3

Topic

Hypocalcemia — Clinical Signs

Difficulty

medium

Template Id

T8

Examiner Tip

The key to 3-mark clinical sign questions is: Name it → How to do it → What positive looks like → Nursing implication. This four-part structure earns all the marks consistently.

Model Answer

Hypocalcemia is defined as total serum calcium below 8.5 mg/dL. It causes neuromuscular hyperexcitability, which can be detected at the bedside using two classic signs: 1. Chvostek's Sign: Elicited by tapping the facial nerve anterior to the ear (pre-auricular area). A positive result is an ipsilateral facial muscle twitch or grimace. This indicates hypocalcemia-induced facial nerve hyperexcitability. 2. Trousseau's Sign: Elicited by inflating a blood pressure cuff on the upper arm to a pressure above systolic for 3 minutes. A positive result is carpal spasm (carpopedal spasm) — an involuntary flexion of the wrist and fingers. This is more specific for hypocalcemia than Chvostek's sign. Both signs are also positive in hypomagnesemia because low magnesium independently increases neuromuscular excitability. The nurse's priority action upon finding positive signs is to notify the physician, prepare IV calcium gluconate, and institute seizure and airway precautions.

Question Type

short_answer

Answer Structure

• Brief definition of hypocalcemia with serum value [0.5 mark]
• Chvostek's sign: name + method of elicitation + positive finding [1 mark]
• Trousseau's sign: name + method of elicitation + positive finding [1 mark]
• Note on hypomagnesemia cross-reactivity and priority nursing action [0.5 mark]

Scoring Breakdown

Common Mark Deductions

• Reversing the two signs (describing Trousseau's elicitation for Chvostek and vice versa)
• Forgetting to mention hypomagnesemia as another cause of positive signs
• Not specifying the nursing priority action after a positive finding
• Omitting the serum calcium normal value

Key Phrases To Include

• below 8.5 mg/dL
• Chvostek's sign
• tap the facial nerve
• facial twitch
• Trousseau's sign
• inflate BP cuff
• carpal spasm
• carpopedal spasm
• hypomagnesemia
• IV calcium gluconate
• seizure precautions

Marks

3

Topic

IV Fluid Tonicity

Difficulty

medium

Template Id

T9

Examiner Tip

For compare-contrast questions, use parallel structure — address the same attributes (example, osmolality, fluid shift, indication, caution) in the same order for each type. This makes grading clear and earns all marks efficiently.

Model Answer

Intravenous (IV) fluid tonicity determines how fluid shifts between the intravascular space and body cells. 1. Isotonic Solutions (e.g., 0.9% NaCl, Lactated Ringer's): Osmolality is close to plasma (~280–300 mOsm/L). No net fluid shift between compartments. Used for: hypovolemia, hemorrhage, shock. Caution: can cause fluid overload/hypervolemia. 2. Hypotonic Solutions (e.g., 0.45% NaCl): Osmolality is lower than plasma. Water moves into the cells (intracellular). Used for: cellular dehydration, hypernatremia. Caution: contraindicated in patients with increased intracranial pressure (ICP) — worsens cerebral edema; avoid in hypovolemia. 3. Hypertonic Solutions (e.g., 3% NaCl, D10W): Osmolality is higher than plasma. Water moves out of cells into the ECF. Used for: severe symptomatic hyponatremia, cerebral edema. Caution: monitor closely for pulmonary edema and fluid overload; give 3% saline slowly with frequent serum sodium checks.

Question Type

short_answer

Answer Structure

• Isotonic: example + osmolality + fluid shift + indication + caution [1 mark]
• Hypotonic: example + osmolality + fluid shift + indication + caution [1 mark]
• Hypertonic: example + osmolality + fluid shift + indication + caution [1 mark]

Scoring Breakdown

Common Mark Deductions

• Stating D5W is isotonic without noting it becomes hypotonic after dextrose metabolism
• Not mentioning the ICP caution for hypotonic fluids
• Confusing which direction water shifts for hypotonic versus hypertonic
• Not including a drug example for each type

Key Phrases To Include

• 0.9% NaCl
• Lactated Ringer's
• 0.45% NaCl
• 3% NaCl
• no net fluid shift
• water moves into cells
• water moves out of cells
• increased ICP
• hypovolemia
• pulmonary edema

Marks

5

Topic

Hyperkalemia — Comprehensive Nursing Management

Difficulty

hard

Template Id

T10

Examiner Tip

For 5-mark case study questions, follow the sequence: Assess → Diagnose → Plan → Implement (in priority order) → Evaluate. Examiners allocate 1 mark to each major phase. The single most common error in hyperkalemia questions is stating that calcium gluconate lowers potassium — examiners specifically watch for and deduct for this mistake.

Model Answer

Introduction: Hyperkalemia is defined as serum potassium above 5.0 mEq/L. In this case, the patient's serum potassium of 6.2 mEq/L with ECG changes indicates severe, life-threatening hyperkalemia requiring immediate priority nursing action. I. Assessment (A — Airway, Breathing, Circulation, followed by focused assessment): - Monitor cardiac rhythm continuously — identify tall peaked T waves, widening QRS, or further ECG deterioration. - Assess neuromuscular status: muscle weakness, paresthesias, flaccid paralysis. - Review causative factor: CKD impairs renal potassium excretion. - Confirm other lab values: serum creatinine, BUN, ABG (acidosis shifts potassium out of cells). II. Priority Nursing Diagnosis (NANDA): - Risk for Decreased Cardiac Output related to hyperkalemia-induced dysrhythmia as evidenced by serum K⁺ 6.2 mEq/L and peaked T waves on ECG. III. Priority Nursing Interventions (in order of urgency based on Maslow's hierarchy — Physiological safety first): 1. Cardiac membrane stabilization (PRIORITY — protect the myocardium first): - Administer IV calcium gluconate as ordered — this does NOT lower potassium but stabilizes the cardiac cell membrane immediately, reducing risk of ventricular fibrillation. Monitor HR, BP, and ECG continuously during administration. 2. Shift potassium into cells (reduces serum potassium within 15–30 minutes): - Administer regular insulin with dextrose (D50) as ordered — insulin drives K⁺ into cells; dextrose prevents hypoglycemia. - Administer sodium bicarbonate if the patient has concurrent metabolic acidosis — alkalinization shifts K⁺ intracellularly. 3. Remove potassium from the body (longer-term reduction): - Administer sodium polystyrene sulfonate (Kayexalate) orally or rectally as ordered — exchanges sodium for potassium in the GI tract. - Prepare for dialysis if the patient does not respond to pharmacologic management — dialysis is the most definitive treatment in CKD. 4. Dietary restriction: - Restrict potassium-rich foods (bananas, oranges, tomatoes, potatoes). - Review and withhold medications that elevate potassium: potassium-sparing diuretics (spironolactone), ACE inhibitors, NSAIDs. 5. Continuous monitoring: - Strict I&O monitoring — in CKD, urine output may already be impaired. - Repeat serum potassium levels per physician's order to evaluate treatment response. - Document and report any worsening ECG changes or new dysrhythmias immediately. IV. Expected Outcome: Serum potassium will return to 3.5–5.0 mEq/L, ECG will normalize, and the patient will remain free of life-threatening cardiac dysrhythmias.

Question Type

case_study

Answer Structure

• Introduction: define hyperkalemia with serum value; state urgency [0.5 mark]
• Assessment: cardiac monitoring, neuromuscular status, causative factor (CKD), lab review [1 mark]
• Priority NANDA nursing diagnosis with related-to and as-evidenced-by [0.5 mark]
• Priority Intervention 1: IV calcium gluconate with rationale (stabilizes membrane, does NOT lower K⁺) [1 mark]
• Priority Intervention 2: Insulin + dextrose and/or sodium bicarbonate to shift K⁺ [0.5 mark]
• Priority Intervention 3: Kayexalate and/or dialysis to remove K⁺ [0.5 mark]
• Dietary restriction and medication review [0.5 mark]
• Expected patient outcome with target serum K⁺ value [0.5 mark]

Scoring Breakdown

Common Mark Deductions

• Stating calcium gluconate lowers potassium (it does NOT — it only protects the heart)
• Not following the correct order: stabilize → shift → remove
• Omitting the NANDA nursing diagnosis with related-to and as-evidenced-by components
• Not mentioning dialysis as the definitive treatment in CKD
• Failing to state a measurable expected outcome
• Not connecting CKD as the reason for impaired potassium excretion

Key Phrases To Include

• K⁺ above 5.0 mEq/L
• tall peaked T waves
• ventricular fibrillation
• calcium gluconate stabilizes cardiac membrane — does NOT lower potassium
• regular insulin with dextrose D50
• sodium polystyrene sulfonate Kayexalate
• dialysis
• restrict potassium-rich foods
• Risk for Decreased Cardiac Output (NANDA)
• 3.5–5.0 mEq/L

Marks

5

Topic

Fluid Volume Excess — Comprehensive Nursing Management

Difficulty

hard

Template Id

T11

Examiner Tip

In 5-mark questions on fluid excess, examiners are specifically looking for Maslow-based prioritization — high-Fowler's before furosemide, because positioning addresses breathing (a physiological need) with zero delay and zero risk. Stating this rationale explicitly earns differentiation marks.

Model Answer

Introduction: Fluid Volume Excess (FVE) or hypervolemia is the isotonic expansion of extracellular fluid (ECF), commonly caused by heart failure, chronic renal failure, or over-infusion of IV fluids. It represents one of the most common fluid complications encountered in Philippine acute care settings. I. Priority Assessment Findings: - Cardiovascular: bounding pulse, elevated blood pressure, distended jugular neck veins. - Respiratory: crackles (rales) on auscultation, dyspnea, orthopnea — most critical finding (airway/breathing = Maslow's top priority). - Peripheral: pitting edema (dependent and peripheral), weight gain (2 kg overnight is significant). - Laboratory: decreased hematocrit (hemodilution), decreased serum sodium (dilutional hyponatremia). II. Priority Nursing Diagnosis (NANDA): - Excess Fluid Volume related to compromised regulatory mechanisms (heart failure/renal failure) as evidenced by crackles, elevated BP, peripheral edema, and weight gain. III. Priority Nursing Interventions (Maslow's hierarchy — Breathing first): 1. PRIORITY — Position in high-Fowler's (90°): Elevates the diaphragm, improves lung expansion, reduces work of breathing and pulmonary congestion. If the patient develops acute pulmonary edema, this is the immediate intervention before medications. 2. Administer diuretics as ordered (e.g., furosemide — loop diuretic): Promotes renal excretion of sodium and water. Monitor for complications of diuresis: hypokalemia (check serum K⁺ and replenish as ordered), hypotension, and dehydration. 3. Restrict sodium and fluid intake: Sodium restriction prevents further water retention. Fluid restriction limits total intake — document all fluid sources including IV, oral, and tube feeding. 4. Monitor I&O and daily weight: Weigh at the same time each day, same scale, same clothing. A loss of 1 kg ≈ 1 L of fluid. Report weight gain of 1–2 kg in 24 hours. 5. Auscultate breath sounds frequently: Monitor for worsening crackles or development of acute pulmonary edema — the most dangerous complication of FVE. Report new or worsening respiratory findings immediately. 6. Supplemental oxygen as ordered: If oxygen saturation falls below 95%, apply oxygen to maintain adequate tissue perfusion. IV. Patient and Family Teaching: - Weigh daily at home; report a weight gain of 1–2 kg in one day to the physician immediately. - Restrict sodium intake — avoid processed foods, canned goods, and salty snacks (common in the Philippine diet such as bagoong, tuyo, and instant noodles). - Take diuretics in the morning to avoid nocturia and ensure diuresis during waking hours. - Adhere to fluid restrictions and recognize signs of worsening FVE: increasing shortness of breath, leg swelling, or inability to lie flat. - Attend regular follow-up under the DOH Philippine Package of Essential NCD Interventions (PhilPEN) for CKD and heart failure management. V. Expected Outcome: Patient's respiratory status improves, crackles resolve, blood pressure normalizes, urine output increases, and body weight returns to baseline without signs of respiratory distress.

Question Type

long_answer

Answer Structure

• Introduction: define FVE, state causes relevant to Philippine setting [0.5 mark]
• Priority assessment data across body systems — respiratory finding cited as highest priority [1 mark]
• NANDA nursing diagnosis with related-to and as-evidenced-by [0.5 mark]
• Priority interventions in Maslow order: high-Fowler's first → diuretics → I&O → breath sounds [1.5 marks]
• Patient and family teaching with Philippine-specific dietary context [1 mark]
• Expected outcome [0.5 mark]

Scoring Breakdown

Common Mark Deductions

• Placing diuretic administration before positioning in priority order — airway/breathing always comes first
• Not specifying the type of diuretic and its hypokalemia risk
• Giving generic patient teaching without Philippine dietary context
• Omitting the daily weighing instruction and 1–2 kg alert threshold
• Not connecting FVE to its most feared complication: pulmonary edema

Key Phrases To Include

• isotonic ECF expansion
• high-Fowler's position priority
• crackles — respiratory priority (Maslow)
• furosemide — loop diuretic
• monitor for hypokalemia
• sodium restriction
• 1 kg = 1 L fluid
• Excess Fluid Volume (NANDA)
• acute pulmonary edema
• diuretics in the morning
• PhilPEN

Marks

2

Topic

IV Fluid Tonicity — Hypernatremia

Difficulty

medium

Template Id

T12

Examiner Tip

Always pair the fluid choice with a mechanistic rationale and a safety consideration — this transforms a 1-mark answer into a full 2-mark answer and demonstrates clinical understanding beyond simple recall.

Model Answer

The IV fluid of choice for hypernatremia with cellular dehydration is a hypotonic solution, specifically 0.45% NaCl (half-normal saline). Rationale: Hypernatremia (serum Na⁺ above 145 mEq/L) creates a high serum osmolality that draws water out of the cells, causing cellular shrinkage. Infusing 0.45% NaCl, which has a lower osmolality than plasma, creates an osmotic gradient that moves water back into the cells, correcting cellular dehydration. Importantly, hypernatremia must be corrected slowly to prevent a rapid influx of water into brain cells, which can cause cerebral edema.

Question Type

short_answer

Answer Structure

• Name the correct fluid with specific concentration [0.5 mark]
• Explain the pathophysiology of hypernatremia (cellular shrinkage) [0.5 mark]
• Explain the mechanism of the hypotonic fluid (water moves into cells) [0.5 mark]
• Safety note: correct slowly to prevent cerebral edema [0.5 mark]

Scoring Breakdown

Common Mark Deductions

• Selecting 0.9% NaCl (isotonic) instead of 0.45% NaCl — this will not correct cellular dehydration
• Not providing the correct serum sodium threshold for hypernatremia
• Omitting the slow correction safety note

Key Phrases To Include

• 0.45% NaCl
• hypotonic solution
• above 145 mEq/L
• cellular dehydration
• water moves into cells
• correct slowly
• cerebral edema

Marks

3

Topic

Metabolic Alkalosis — ABG Interpretation

Difficulty

hard

Template Id

T13

Examiner Tip

Always determine compensation status by checking whether the non-primary system has moved. If PaCO₂ is normal in a metabolic disorder, there is NO respiratory compensation yet — it is uncompensated. Examiners deduct a full mark for calling it 'compensated' when PaCO₂ is within normal range.

Model Answer

Step 1 — pH: 7.51 is above 7.45, indicating alkalosis. Step 2 — PaCO₂: 42 mmHg is within normal range (35–45 mmHg) — no respiratory component. Step 3 — HCO₃⁻: 31 mEq/L is above 26 mEq/L (elevated). Using ROME — Metabolic Equal: pH is high and HCO₃⁻ is also high (both elevated — same direction), confirming metabolic origin. Interpretation: Uncompensated Metabolic Alkalosis (PaCO₂ is still normal, indicating compensation has not yet occurred). Cause: Prolonged nasogastric suctioning removes HCl (hydrochloric acid) from the stomach, causing a loss of hydrogen ions (H⁺) from the ECF. This increases the relative bicarbonate concentration, raising the pH. Compensatory Response: The lungs attempt to compensate by hypoventilation (slow, shallow breathing) to retain CO₂ and decrease pH back toward normal. This is called respiratory compensation for metabolic alkalosis. Note: PaCO₂ in this case is still normal (42 mmHg), indicating compensation has not yet been initiated — confirming uncompensated status.

Question Type

short_answer

Answer Structure

• Stepwise ABG interpretation using ROME → identify metabolic alkalosis [1 mark]
• State cause: NG suction removes HCl → loss of H⁺ → elevated HCO₃⁻ [1 mark]
• State compensatory response: hypoventilation → CO₂ retention → pH normalization [1 mark]

Scoring Breakdown

Common Mark Deductions

• Identifying the disorder without showing the ROME reasoning
• Stating compensated instead of uncompensated despite PaCO₂ being normal
• Confusing the compensatory mechanism (stating hyperventilation instead of hypoventilation)
• Not explaining the physiologic link between NG suction and alkalosis

Key Phrases To Include

• pH 7.51 — alkalosis
• HCO₃⁻ 31 — elevated
• ROME — Metabolic Equal
• Uncompensated Metabolic Alkalosis
• NG suction removes HCl
• loss of H⁺
• hypoventilation to retain CO₂
• PaCO₂ normal — uncompensated

Marks

2

Topic

Hypomagnesemia

Difficulty

medium

Template Id

T14

Examiner Tip

The DTR monitoring point is what separates a 1-mark answer from a 2-mark answer in hypomagnesemia questions. Always include it — it demonstrates safety-focused nursing thinking that examiners reward.

Model Answer

Hypomagnesemia is defined as serum magnesium below 1.5 mEq/L. Causes (two): (1) Chronic alcoholism — poor dietary intake and increased urinary magnesium excretion; (2) Prolonged GI losses — vomiting, diarrhea, or prolonged nasogastric suction depletes magnesium stores. Clinical manifestations (two): (1) Neuromuscular irritability — tremors, tetany, positive Chvostek's and Trousseau's signs (similar to hypocalcemia); (2) Cardiac dysrhythmias — torsades de pointes is the classic life-threatening dysrhythmia associated with hypomagnesemia. Treatment: The correction is IV magnesium sulfate (MgSO₄). Importantly, deep tendon reflexes (DTRs) must be monitored before each dose — loss of DTRs is the first sign of magnesium toxicity (hypermagnesemia).

Question Type

short_answer

Answer Structure

• Two causes with brief rationale [0.5 mark]
• Two clinical manifestations [0.5 mark]
• Antidote/treatment with monitoring consideration [1 mark]

Scoring Breakdown

Common Mark Deductions

• Confusing hypomagnesemia treatment with hypocalcemia treatment (writing calcium gluconate instead of MgSO₄)
• Not mentioning DTR monitoring as the toxicity indicator
• Listing only one cause or one manifestation when two are required

Key Phrases To Include

• below 1.5 mEq/L
• alcoholism
• GI losses
• Chvostek's and Trousseau's signs
• torsades de pointes
• IV magnesium sulfate
• monitor deep tendon reflexes
• DTR loss = toxicity

Marks

1

Topic

Sodium Imbalances — Correction Safety

Difficulty

medium

Template Id

T15

Examiner Tip

This is a classic NLE-style 1-mark recall question. The answer lives or dies on knowing the specific term: 'osmotic demyelination syndrome' or 'central pontine myelinolysis.' Vague answers like 'brain problem' do not earn the mark.

Model Answer

Rapid correction of hyponatremia with hypertonic saline causes osmotic demyelination syndrome (ODS), also called central pontine myelinolysis — a potentially irreversible destruction of the myelin sheath in the brainstem pons due to abrupt osmotic shifts. This is why sodium must be corrected slowly, at a rate not exceeding 10–12 mEq/L per 24 hours.

Question Type

very_short_answer

Answer Structure

• Name the condition (osmotic demyelination / central pontine myelinolysis) and state the mechanism [1 mark]

Scoring Breakdown

Common Mark Deductions

• Stating cerebral edema (which is a risk of rapid hypernatremia correction — not hyponatremia)
• Not naming the specific condition — writing only 'brain damage' without the clinical term

Key Phrases To Include

• osmotic demyelination syndrome
• central pontine myelinolysis
• rapid correction
• correct slowly
• pons
• myelin sheath