Module 8 of 9 · Free NCLEX Prep Course · The RN Network
Catching complications before they become emergencies: lab values, diagnostic procedures, and post-operative vigilance. The lab table in this module is the single highest-yield memorization on the exam.
The Must-Know Lab Values
Potassium 3.5–5.0 mEq/L — the most tested value on the NCLEX; both extremes cause lethal arrhythmias.
Sodium 135–145 mEq/L (neuro symptoms at extremes) · Calcium ~9–10.5 mg/dL (Trousseau/Chvostek when low) · Magnesium ~1.5–2.5 mEq/L.
Glucose fasting 70–99 mg/dL · HbA1c goal for many with diabetes under 7%.
BUN 10–20 mg/dL · Creatinine ~0.6–1.2 mg/dL (the kidney number — trend it before nephrotoxic drugs and contrast) · GFR below 60 = impaired.
INR 2–3 on warfarin · aPTT therapeutic on heparin 1.5–2.5× control · Troponin elevation = myocardial injury · BNP elevation = heart failure.
ABGs: pH 7.35–7.45, PaCO2 35–45, HCO3 22–26 — use ROME (Respiratory Opposite, Metabolic Equal) to classify.
Pre- and Post-Procedure Care
Cardiac catheterization: check allergies (contrast/shellfish per policy), mark distal pulses; after — pressure and flat extremity per protocol, monitor the site for bleeding/hematoma, compare distal pulses, push fluids to clear contrast, watch urine output.
Liver biopsy: check coagulation studies BEFORE; after — position on the RIGHT side to splint the puncture site, watch for hemorrhage (tachycardia first).
Lumbar puncture: empty bladder before; after — lie flat, push fluids, report severe headache (blood patch for persistent spinal headache).
Thoracentesis: sit upright leaning over a table; after — watch for pneumothorax (dyspnea, absent sounds, tracheal shift).
EGD/bronchoscopy: NPO before; after — NOTHING by mouth until the gag reflex returns.
Paracentesis: void first (bladder injury risk), monitor BP for hypotension after large-volume drainage.
MRI: screen for metal implants and pumps; contrast studies: check creatinine and metformin policy.
Post-Operative Complication Watch
First 24 hours: hemorrhage (tachycardia, falling BP, restlessness — check under the client for pooling) and airway/atelectasis (incentive spirometer 10×/hour awake, early ambulation).
Days 1–3: atelectasis and pneumonia (fever + diminished sounds), urinary retention (bladder scan 6–8 hours post-op if no void).
Days 3–5+: wound infection (redness, purulence, fever), DVT (unilateral calf swelling/warmth — do NOT massage; anticoagulate per orders; PE presents as sudden dyspnea, pleuritic chest pain, tachycardia).
Dehiscence (wound edges separate) and evisceration (organs protrude): stay with the client, cover viscera with sterile saline-moistened gauze, low-Fowler's with knees flexed, NPO, notify surgeon — never push anything back in.
Paralytic ileus: absent bowel sounds with distension — advance diet only after function returns; early ambulation is the best prevention.
Malignant hyperthermia (intra/post-op emergency): rigidity, rising CO2, hyperthermia — dantrolene is the drug.
Recognizing Deterioration Early
Trends beat snapshots: rising respiratory rate, narrowing pulse pressure, falling urine output (<30 mL/hr), and new restlessness/confusion are the classic early warnings — do not wait for hypotension.
Restlessness and tachycardia are early hypoxia; cyanosis and bradycardia are late — act early.
Compartment syndrome: pain unrelieved by opioids and out of proportion, pain on passive stretch, pressure, paresthesia — pulselessness is LATE. Loosen constrictive devices, keep limb at heart level, call the provider now (fasciotomy).
Neurovascular checks after casts/fractures: the 6 P's every assessment; compare bilaterally.
Sepsis screening: suspected infection + two of altered mentation, RR ≥22, SBP ≤100 — cultures, lactate, broad-spectrum antibiotics, and fluids fast per bundle.
When findings are critical, the sequence is: stabilize the client with independent nursing actions, then SBAR the provider — the NCLEX rarely rewards "call the provider" while the client is unattended.
Practice Questions
Answer each question, then read the rationale — the rationale is where the learning happens.
1.The nurse reviews morning labs. Which value requires the MOST immediate provider notification?
Rationale: Potassium 6.8 is critical hyperkalemia — risk of lethal arrhythmias. Expect an ECG, IV calcium gluconate to protect the myocardium, and insulin with dextrose to shift potassium. The sodium is barely low; platelets and creatinine are normal.
2.Four hours after cardiac catheterization via the femoral artery, the client reports back pain, and the nurse notes a heart rate of 118 with BP 92/58. What should the nurse suspect and do FIRST?
Rationale: Back/flank pain with tachycardia and falling BP after femoral access suggests retroperitoneal hemorrhage — bleeding may be invisible externally. Assess, hold pressure, and escalate immediately. Treating it as routine pain misses a life-threatening bleed.
3.After an esophagogastroduodenoscopy (EGD), which assessment must be completed before the client resumes oral intake?
Rationale: The throat is anesthetized for EGD; feeding before the gag reflex returns risks aspiration. Bowel sounds, ambulation, and labs do not determine swallowing safety.
4.A client in a long leg cast reports increasing pain unrelieved by the prescribed opioid, with tingling in the toes. The nurse notes the toes are pale and painful on passive stretch. What is the priority action?
Rationale: Pain out of proportion and unrelieved by opioids, paresthesia, pallor, and pain on passive stretch are compartment syndrome until proven otherwise — a limb-threatening emergency requiring immediate provider notification and possible fasciotomy. Elevating above heart level further reduces perfusion; waiting loses the limb.
5.While coughing, a post-op abdominal surgery client feels a "pop," and the nurse finds a loop of bowel protruding through the incision. Which actions should the nurse take?
Rationale: Evisceration is a surgical emergency: protect the viscera with sterile saline-moistened gauze, reduce tension on the incision (low-Fowler's, knees flexed), NPO for imminent surgery, stay with the client, and notify the surgeon. Never reinsert organs or apply pressure.
6.The nurse is trending vital signs on a post-op client: RR 18→24→28, HR 88→102→118, urine output last hour 20 mL. BP remains 118/74. How should the nurse interpret these data?
Rationale: Rising respiratory and heart rates with falling urine output are classic early (compensated) shock — blood pressure is the LAST thing to fall. Recognizing deterioration from trends and escalating before hypotension is exactly what this category tests.