Critical Care Nursing Flashcards

A 58-year-old male patient in the ICU is on mechanical ventilation with the following ABG results: pH 7.22, PaCO₂ 38 mmHg, HCO₃⁻ 15 mEq/L, PaO₂ 88 mmHg on FiO₂ 0.40. The anion gap is 24 mEq/L (Na⁺ 138, Cl⁻ 99, HCO₃⁻ 15). Which of the following is the MOST appropriate next diagnostic step according to SCFHS critical care standards?

Answer: Calculate the delta-delta ratio to determine if a concurrent metabolic alkalosis is masked

The ABG shows a high anion gap metabolic acidosis (HAGMA) with an anion gap of 24 (normal 8–12). With a normal PaCO₂, there is no respiratory compensation, suggesting a concurrent process. The delta-delta ratio (ΔAG/ΔHCO₃⁻) = (24–12)/(24–15) = 12/9 ≈ 1.33, which falls in the 1–2 range — indicating a pure HAGMA. However, calculating the delta-delta is the mandatory next step to exclude a mixed disorder before any intervention. Blindly increasing ventilator rate addresses only respiratory parameters and misses the metabolic cause. Sodium bicarbonate is controversial and not first-line in HAGMA without identifying the underlying etiology. Waiting 4 hours is inappropriate in an unstable ICU patient.

A post-cardiac surgery patient in a Saudi tertiary hospital ICU develops sudden hypotension (BP 70/40 mmHg), elevated CVP of 22 mmHg, muffled heart sounds, and pulsus paradoxus of 18 mmHg. The 12-lead ECG shows electrical alternans. Which hemodynamic profile on pulmonary artery catheter would BEST confirm the diagnosis?

Answer: Equalization of RVEDP, LVEDP, and PAWP within 5 mmHg of each other

The clinical picture describes cardiac tamponade: Beck's triad (hypotension, elevated JVP/CVP, muffled heart sounds), pulsus paradoxus >10 mmHg, and electrical alternans on ECG. The pathognomonic PA catheter finding in tamponade is equalization of diastolic pressures — RVEDP, LVEDP, and PAWP all equilibrate within 5 mmHg of each other due to the constraining effect of pericardial fluid on all chambers. Option B describes cardiogenic shock. Option C describes distributive (septic) shock. Option D describes pulmonary hypertension.

In a Saudi ICU, a mechanically ventilated patient with ARDS (P/F ratio 95) is being managed with lung-protective ventilation per the ARDSNet protocol. Despite optimizing PEEP to 14 cmH₂O and prone positioning for 18 hours, the patient's plateau pressure is 32 cmH₂O and driving pressure is 18 cmH₂O. The ICU consultant orders neuromuscular blockade. Which agent is the SCFHS/Saudi MOH-preferred first-line neuromuscular blocking agent for early moderate-to-severe ARDS, and what monitoring parameter is MANDATORY during its use?

Answer: Cisatracurium infusion; Train-of-Four (TOF) monitoring with target of 1–2 twitches

Cisatracurium is the preferred NMBA for early moderate-to-severe ARDS (P/F <150) based on the ACURASYS trial and international critical care guidelines adopted by SCFHS. Its organ-independent Hofmann elimination makes it safe in hepatic and renal failure, which is common in ICU patients. The mandatory monitoring parameter is Train-of-Four (TOF) stimulation, targeting 1–2 twitches out of 4 to ensure adequate blockade without overdose and cumulative paralysis. Succinylcholine is an ultra-short depolarizing agent used only for intubation, not infusion. Rocuronium requires TOF monitoring but is second-line. Vecuronium PRN dosing without TOF is unsafe and non-standard.

A 44-year-old female patient in a SCFHS-accredited ICU is receiving continuous renal replacement therapy (CRRT) for acute kidney injury secondary to septic shock. Her ionized calcium is 0.88 mmol/L (normal 1.15–1.35 mmol/L). She is on regional citrate anticoagulation for the CRRT circuit. Which finding would indicate systemic citrate toxicity rather than simple hypocalcemia from the sepsis itself?

Answer: Total calcium to ionized calcium ratio greater than 2.5 with metabolic alkalosis

Systemic citrate toxicity occurs when the liver cannot metabolize citrate rapidly enough (e.g., in severe hepatic dysfunction), leading to citrate accumulation. Citrate chelates calcium, so both total and ionized calcium fall. The hallmark finding is a total calcium to ionized calcium ratio >2.5 (or sometimes cited as >2.1), because total calcium (which includes calcium bound to citrate complexes) rises relative to free ionized calcium. This ratio, combined with metabolic alkalosis (citrate is metabolized to bicarbonate), distinguishes systemic citrate accumulation from simple hypocalcemia. Options B, C, and D represent general hypocalcemia signs that could occur from any cause, not specifically citrate toxicity.

A 67-year-old male admitted to a Saudi MOH ICU following a massive ischemic stroke develops fever (39.8°C), hypertension (BP 195/110 mmHg), bradycardia (HR 44 bpm), and irregular respirations. CT head shows significant cerebral edema with midline shift of 8 mm. Intracranial pressure (ICP) monitoring shows ICP 32 mmHg and cerebral perfusion pressure (CPP) of 55 mmHg. Per SCFHS neurocritical care guidelines, which intervention should be PRIORITIZED FIRST?

Answer: Administer 23.4% hypertonic saline 30 mL IV bolus to acutely lower ICP

The patient has Cushing's triad (hypertension, bradycardia, irregular respirations) indicating critically elevated ICP with impending herniation, and ICP of 32 mmHg with CPP of only 55 mmHg (target is ≥60 mmHg). The immediate priority is to acutely reduce ICP. In refractory or acute ICP crisis, 23.4% hypertonic saline (30 mL bolus) provides rapid osmotic reduction of cerebral edema and is the most potent acute pharmacological ICP-lowering agent, superior to mannitol in this context. Therapeutic hypothermia (option B) is not first-line for ischemic stroke. Lowering MAP with labetalol (option C) would dangerously reduce CPP further (CPP = MAP − ICP). Hemicraniectomy (option D) is a surgical option but not the immediate first priority before medical management is maximized.

During morning rounds in a SCFHS-certified ICU, a nurse notes that a patient on a norepinephrine infusion of 0.35 mcg/kg/min for vasodilatory shock has developed mottling to the knees, urine output of 8 mL/hr for the past 3 hours, and a lactate that has risen from 3.1 to 5.8 mmol/L over 6 hours despite fluid resuscitation. ScvO₂ is 58%. Echocardiography shows an EF of 20%. Which vasoactive agent should be added NEXT according to advanced vasopressor management principles endorsed by SCFHS critical care guidelines?

Answer: Vasopressin 0.03–0.04 units/min as a fixed-dose adjunct to spare catecholamine dose

The patient has combined vasodilatory and cardiogenic shock (low EF 20%, rising lactate, low ScvO₂ 58%, high norepinephrine dose). Vasopressin at 0.03–0.04 units/min acts on V1 receptors independently of adrenergic pathways, allowing norepinephrine dose reduction (catecholamine sparing), reducing tachyarrhythmia risk, and maintaining MAP without worsening myocardial oxygen demand. This is the VASST/VANISH trial–supported strategy adopted in SCFHS critical care frameworks. Phenylephrine (option B) is a pure alpha-1 agent that reduces cardiac output via reflex bradycardia — harmful in low EF states. Dopamine (option C) has no proven renal protective effect and increases arrhythmia risk. Epinephrine (option D) increases cardiac output but significantly raises lactate due to beta-2 stimulation, confounding lactate clearance monitoring and worsening the metabolic picture.