Study Guide: Critical Care | 4F | Before Class
Critical Care
Study Guide · Class 1
Prepare to interpret urgent clinical findings, prioritize nursing actions, explain your reasoning, and evaluate patient outcomes.
Prepare to Participate
Review the concepts before class. During discussion, use the patient’s assessment, laboratory results, and clinical trends to support your decisions. Be ready to identify immediate threats, explain the safest nursing action, and describe what you would reassess.
What is the immediate threat? Which findings support it? What must happen first? What findings will show improvement or deterioration?
Use the Clinical Judgment Cycle
Hemodynamic Monitoring & Perfusion
Interpret trends rather than isolated numbers, especially in postoperative and unstable patients.
Connect the Measurements
MAP reflects the pressure driving organ perfusion. CVP provides information about right-sided filling pressure but does not independently establish fluid responsiveness. Heart rate, mental status, skin findings, and urine output help assess perfusion.
Recognize Deterioration
Falling MAP, increasing tachycardia, reduced urine output, altered mentation, and ongoing blood loss may indicate impaired perfusion. Evaluate these findings together and compare them with the patient’s baseline.
Assess Postoperative Bleeding
Monitor chest tube output, drainage characteristics, vital signs, and laboratory trends after cardiac surgery. Rapidly increasing sanguineous drainage or output exceeding ordered notification parameters requires urgent escalation.
Evaluate Interventions
Trend MAP, urine output, mentation, peripheral perfusion, drainage, and laboratory results. Improvement in one measurement does not always indicate adequate overall perfusion.
ABG Interpretation & Ventilatory Failure
Distinguish oxygenation from ventilation and connect arterial blood gases with the patient’s clinical condition.
Interpret Systematically
Review pH, PaCO₂, and HCO₃⁻. Identify acidemia or alkalemia, determine the primary respiratory or metabolic disturbance, and evaluate compensation. Use clinical history and trends to identify mixed disorders when suspected.
Know the Reference Ranges
Typical adult values: pH 7.35–7.45; PaCO₂ 35–45 mm Hg; HCO₃⁻ 22–26 mEq/L; PaO₂ approximately 80–100 mm Hg at sea level, with variation by age and clinical circumstances.
Recognize Ventilatory Failure
Elevated PaCO₂ with acidemia suggests inadequate alveolar ventilation. Progressive somnolence, reduced responsiveness, exhaustion, or inability to protect the airway raises concern for worsening respiratory failure.
Match Support to the Patient
Noninvasive ventilation may benefit selected patients with acute hypercapnic respiratory failure. Assess mental status, airway protection, hemodynamic stability, secretion management, and contraindications. Escalate urgently when invasive airway support may be necessary.
Lethal Dysrhythmias & Electrical Therapy
Identify the rhythm, determine whether a pulse is present, and assess hemodynamic stability.
Assess Before Selecting Treatment
Evaluate responsiveness, pulse, blood pressure, chest discomfort, mental status, and signs of shock. Treatment depends on both the rhythm and the patient’s clinical condition.
Distinguish Electrical Interventions
Synchronized cardioversion is generally indicated for unstable tachyarrhythmias with a pulse when synchronization is feasible. Defibrillation is used for ventricular fibrillation and pulseless ventricular tachycardia, and for certain unstable rhythms when synchronization cannot be achieved.
Recognize Medication Limitations
Medications appropriate for stable tachyarrhythmias may be inappropriate when a patient requires immediate electrical treatment. Adenosine has a limited role in selected regular rhythms and should not delay cardioversion in an unstable patient.
Reassess After Treatment
Evaluate rhythm, pulse, blood pressure, consciousness, oxygenation, and recurrence. A rhythm change alone does not establish adequate perfusion.
ARDS & Mechanical Ventilation
Recognize severe oxygenation impairment and understand lung-protective ventilation.
Recognize the Clinical Pattern
ARDS involves acute hypoxemic respiratory failure with bilateral pulmonary opacities not fully explained by cardiac failure or fluid overload. Interpret oxygenation severity with the clinical context and applicable diagnostic criteria.
Understand Lung Protection
Lung-protective ventilation commonly uses tidal volumes near 6 mL/kg predicted body weight and limits plateau pressure, generally to 30 cm H₂O or less. Predicted body weight is based on height and sex, not actual weight.
Understand Prone Positioning
Prolonged prone positioning can improve oxygenation and outcomes in selected patients with severe ARDS. The team must protect the airway, lines, skin, eyes, and pressure-sensitive areas during repositioning.
Evaluate Oxygenation and Safety
Trend SpO₂, PaO₂, FiO₂, ventilator pressures, hemodynamics, and patient-ventilator synchrony. Sedation is individualized to the patient’s condition, ventilation goals, and safety needs.
Aortic Dissection & Acute Vascular Emergencies
Recognize findings suggesting an acute aortic syndrome and understand anti-impulse therapy.
Recognize Concerning Findings
Sudden severe chest, back, or abdominal pain, pulse deficits, blood pressure differences, syncope, or new neurologic findings may indicate aortic dissection. Not every patient presents with classic tearing pain.
Understand the Hemodynamic Goal
In appropriate hypertensive patients, IV beta-blockade reduces heart rate and the force of ventricular contraction, lowering aortic wall stress. Additional blood pressure reduction may be required after rate control, according to orders and clinical status.
Avoid Dangerous Assumptions
Chest pain should not automatically be treated as acute coronary syndrome when dissection is suspected. Anticoagulation or thrombolysis intended for another diagnosis can cause serious harm if given inappropriately.
Escalate Rapidly
Maintain close hemodynamic and neurologic monitoring, establish access, and prepare for urgent imaging and specialist evaluation. Treatment depends on dissection location, complications, and stability.
Ventilator Alarms & Airway Emergencies
Assess the patient first and connect alarm patterns with possible mechanical and physiologic causes.
High-Pressure Alarms
Consider secretions, a kinked tube, biting, bronchospasm, coughing, reduced lung compliance, or pneumothorax. High pressure is not synonymous with obstruction alone.
Low-Pressure Alarms
Consider circuit disconnection, leaks, cuff problems, or other failures to maintain expected airway pressure. Assess the airway device and ventilator circuit promptly.
Prioritize the Patient
Immediately assess oxygenation, chest movement, airway patency, and hemodynamic status. Call for assistance when needed. If ventilation is inadequate, provide manual ventilation with appropriate equipment while the cause is addressed.
Recognize Dangerous Changes
Sudden hypoxemia, hypotension, absent or asymmetric breath sounds, or difficulty ventilating requires urgent evaluation. Consider displacement, obstruction, pneumothorax, and equipment failure.
Acute Coronary Syndrome & STEMI
Recognize ischemia, interpret hemodynamic instability, and evaluate medication safety.
Recognize Ischemic Patterns
Assess chest discomfort, diaphoresis, dyspnea, nausea, ECG changes, and vital signs. Inferior STEMI may involve right ventricular infarction and may be associated with hypotension or bradycardia.
Consider Medication Risks
Nitrates can worsen hypotension and are contraindicated with recent phosphodiesterase-5 inhibitor use within the relevant drug-specific interval. Suspected right ventricular infarction also requires particular caution.
Understand Reperfusion Priorities
Rapid ECG assessment, appropriate antiplatelet therapy, monitoring, and timely reperfusion are central to STEMI care. Reperfusion targets depend on whether the patient presents to a PCI-capable facility and other system factors.
Use Oxygen Appropriately
Supplemental oxygen is not routinely indicated for an otherwise adequately oxygenated patient. Administer oxygen when hypoxemia or another clinical indication is present, according to protocol.
Pulmonary Embolism & Acute Respiratory Deterioration
Connect risk factors, sudden respiratory changes, hemodynamic findings, and treatment monitoring.
Recognize the Pattern
Sudden dyspnea, tachypnea, pleuritic chest pain, tachycardia, hypoxemia, syncope, or hypotension may suggest pulmonary embolism. Risk factors include immobility, recent surgery, and venous thromboembolism history.
Prioritize Stabilization
Assess airway, breathing, circulation, oxygenation, and hemodynamic status. Activate urgent support and prepare prescribed diagnostic testing and treatment. Hemodynamic instability raises concern for high-risk pulmonary embolism.
Understand Treatment
Anticoagulation prevents further thrombus propagation but does not immediately dissolve the existing embolus. Selected high-risk patients may require reperfusion treatment after assessment of bleeding risk and contraindications.
Monitor Effectiveness and Safety
Evaluate respiratory effort, oxygenation, heart rate, blood pressure, and perfusion for clinical response. Separately assess bleeding and other complications associated with anticoagulant treatment.
Cardiac Arrest, PEA & Reversible Causes
Understand coordinated resuscitation and recognize reversible causes of cardiac arrest.
Identify Arrest and Begin CPR
For an unresponsive adult without normal breathing and without a definite pulse after a brief assessment, activate emergency response and begin high-quality CPR. Do not delay compressions while waiting for monitoring equipment.
Differentiate Shockable Rhythms
Ventricular fibrillation and pulseless ventricular tachycardia are shockable. PEA and asystole are nonshockable rhythms. Continue CPR and appropriate medications while evaluating reversible causes.
Recognize Reversible Causes
Consider the Hs and Ts, including hypoxia, hypovolemia, hydrogen ion excess, hypo-/hyperkalemia, hypothermia, tension pneumothorax, tamponade, toxins, and thrombosis. Treat identified causes during ongoing resuscitation.
Coordinate Simultaneous Actions
Chest compressions, airway management, epinephrine administration, rhythm checks, and correction of reversible causes are coordinated by the resuscitation team. Severe hyperkalemia may require targeted treatment during CPR rather than waiting until other steps are completed.
Compare the Clinical Patterns
| Clinical Decision | Pattern A | Pattern B |
|---|---|---|
| Electrical therapy | Unstable tachycardia with a pulse: synchronized cardioversion when appropriate. | VF or pulseless VT: defibrillation with high-quality CPR. |
| Ventilator alarm | High pressure: resistance, obstruction, or decreased compliance. | Low pressure: disconnection or leak. |
| Respiratory assessment | Oxygenation: SpO₂, PaO₂, and oxygen requirements. | Ventilation: PaCO₂, pH, and clinical respiratory effort. |
| Hemodynamic deterioration | Stable perfusion: adequate mentation, urine output, and clinical trends. | Impaired perfusion: falling MAP, oliguria, altered mentation, or shock findings. |
| Treatment monitoring | Effectiveness: improvement in oxygenation, breathing, and perfusion. | Safety: bleeding, medication effects, and treatment complications. |
Build Your Explanation During Class
Identify the Evidence
“The findings that concern me most are… because together they suggest…”
Explain the Priority
“My priority is… because delaying care could lead to…”
Defend the Action
“I would first… because this action addresses…”
Evaluate the Outcome
“I would reassess… and expect improvement in…”
Approach NGN Item Formats
Bow-Tie
Connect the most likely condition with appropriate actions and monitoring parameters. Evaluate whether all selections fit the same clinical situation.
SATA / Highlight
Judge each option or finding independently. Distinguish what is abnormal from what requires immediate nursing intervention.
Matrix
Apply the stated classification rule consistently. Determine whether each row allows one or multiple selections.
Cloze / Ordered Response
Use the clinical context to complete the statement or arrange actions. Remember that some emergency interventions may occur simultaneously in real practice.