What is the acute management of a 48-year-old female with uncorrected truncus arteriosus presenting with hypoxia and hypotension?

Acute Management of Hypoxic and Hypotensive 48-Year-Old Female with Truncus Arteriosus

This patient requires immediate ICU admission with invasive hemodynamic monitoring, cautious fluid resuscitation targeting MAP >65 mmHg, supplemental oxygen to maintain SpO2 >94%, and urgent cardiology/cardiac surgery consultation to assess for decompensated heart failure, truncal valve dysfunction, or other mechanical complications that may require surgical intervention. 1, 2

Immediate Stabilization and Monitoring

Airway and Respiratory Support

• Administer supplemental oxygen immediately to maintain SpO2 >94%, as hypoxia acutely increases pulmonary vascular resistance (PVR) which can further stress the already compromised circulation in truncus arteriosus 1
• Obtain arterial blood gases urgently to assess pH, PaCO2, and lactate, as acidosis and hypercapnea can acutely increase PVR 1, 2
• If respiratory rate >25 breaths/min or SpO2 remains <90% despite oxygen, initiate non-invasive positive pressure ventilation (BiPAP preferred) before considering intubation, as intubation itself acutely decreases right ventricular preload and increases afterload, potentially causing irreversible cardiovascular collapse 1, 2
• If intubation becomes necessary, use an experienced cardiac anesthesiologist, employ fiberoptic awake intubation if possible, and use low tidal volume strategy with peak pressures <30 cmH2O and PEEP ≤10 cmH2O 1

Hemodynamic Monitoring

• Establish invasive arterial line monitoring immediately for continuous blood pressure assessment 1
• Place the patient in ICU/CCU with continuous monitoring of SpO2, heart rate, blood pressure, and urine output 2
• Consider pulmonary artery catheter placement if progressive hypotension is unresponsive to initial fluid administration, as this provides critical data on cardiac output and filling pressures 1

Fluid Resuscitation Strategy

Initial Volume Management

• Begin with cautious IV fluid bolus of 500-1000 mL of normal saline or lactated Ringer's solution, as volume administration titrated to blood pressure improvement is the reasonable first approach for hypotension 1, 3
• Assess fluid responsiveness with passive leg raise test before aggressive volume loading 3
• Target mean arterial pressure >65-70 mmHg during resuscitation to prevent end-organ injury while avoiding excessive fluid that could worsen pulmonary congestion 3, 2
• Monitor closely for signs of volume overload, as patients with truncus arteriosus often have baseline pulmonary overcirculation and are at high risk for pulmonary edema 4

Vasopressor and Inotropic Support

When Fluid Resuscitation is Insufficient

• If hypotension persists despite fluid administration (SBP <90 mmHg or MAP <65 mmHg), initiate norepinephrine infusion as the first-line vasopressor, as it maintains systemic vascular resistance without significantly increasing PVR 1, 3
• Consider adding low-dose vasopressin (replacement-dose) to offset potential drops in systemic vascular resistance, particularly if sepsis is suspected 1
• If low cardiac output state is present (cold extremities, oliguria, altered mentation despite adequate blood pressure), add dobutamine infusion as the preferred inotrope due to its shorter half-life and favorable effect on reducing PVR 1
• Avoid beta-blockers and calcium channel antagonists in this acute setting, as they are contraindicated in low-output states due to pump failure 1

Diagnostic Evaluation for Underlying Cause

Urgent Echocardiography

• Perform urgent transthoracic echocardiography to assess:
  • Truncal valve function (stenosis or regurgitation), as truncal valve abnormalities are common and can cause acute decompensation 5, 6, 7
  • Ventricular function and degree of ventricular septal defect 6
  • Presence of mechanical complications such as severe truncal valve regurgitation 1
  • Pulmonary artery anatomy and flow patterns 4, 7

Additional Diagnostic Considerations

• Obtain ECG and cardiac troponin to rule out myocardial ischemia 2
• Check daily serum electrolytes, urea nitrogen, and creatinine given the renal dysfunction risk 2
• Assess for signs of congestive heart failure, as this is the major cause of decompensation in adults with uncorrected truncus arteriosus 8, 4

Specific Management Based on Underlying Pathophysiology

If Pulmonary Overcirculation/Congestive Heart Failure

• Administer IV furosemide 40-80 mg immediately if signs of pulmonary congestion are present (rales, elevated jugular venous pressure) 2
• Consider IV nitroglycerin starting at 0.25 μg/kg/min if systolic BP >100 mmHg to reduce preload 2
• Administer morphine sulfate 2-4 mg IV for pulmonary congestion and respiratory distress 1, 2

If Truncal Valve Dysfunction

• Urgent cardiac surgery consultation is mandatory, as severe truncal valve stenosis or regurgitation may require valve replacement in addition to definitive repair 5, 6
• Intra-aortic balloon counterpulsation may be considered if hypotension persists and surgical intervention is planned, though this must be carefully weighed against the abnormal anatomy 1

Critical Pitfalls to Avoid

• Do not aggressively fluid resuscitate to normotensive pressures without assessing volume status, as patients with truncus arteriosus often have baseline pulmonary overcirculation and can rapidly develop pulmonary edema 4
• Avoid hyperventilation if mechanical ventilation is required, as this increases intrathoracic pressure and reduces venous return, further compromising cardiac output 1
• Do not delay cardiac surgery consultation, as hypotension in the setting of uncorrected truncus arteriosus suggests severe truncal valve dysfunction or heart failure requiring definitive surgical repair 1, 8, 5
• Recognize that this 48-year-old with uncorrected truncus arteriosus has survived far beyond the median age at death of 5 weeks, suggesting either favorable anatomy or previous palliative intervention that may now be failing 4

Definitive Management Planning

• Immediate cardiac surgery consultation for evaluation of surgical candidacy, as definitive repair with closure of ventricular septal defect, establishment of right ventricle to pulmonary artery continuity, and potential truncal valve replacement may be necessary 8, 5, 6
• If truncal valve abnormalities are confirmed, primary repair should include valve replacement using valved homografts 5
• Coordinate multidisciplinary care involving cardiology, cardiac surgery, and intensive care specialists given the complexity and rarity of this condition in adults 7