Cardiac Output Case Studies: Real-World Clinical Examples

Understanding cardiac output (CO) goes beyond formulas and numbers; it’s about applying this knowledge to real patients. This page presents anonymized, illustrative cardiac output clinical examples and case studies from ICU, ER, and cardiology settings. These cases demonstrate how cardiac output interpretation and calculations can significantly impact diagnosis, treatment strategies, and ultimately, patient outcomes. These examples are for educational purposes and drawn from common clinical scenarios, not specific patient data.

Case Study 1: Undifferentiated Shock in the ER

Patient Profile: A 72-year-old male brought to the ER with altered mental status, cool extremities, and a blood pressure of 85/50 mmHg. Heart rate is 115 bpm. Past medical history includes hypertension and type 2 diabetes.

Initial Assessment & CO Measurement:

• Clinical picture suggests shock. The ER physician performs a quick point-of-care ultrasound (POCUS).
• Basic cardiac views show a hyperdynamic left ventricle with a small cavity. IVC is small and collapses >50% with respiration.
• A quick LVOT VTI measurement (e.g., 12 cm) and LVOT diameter (e.g., 2.0 cm) are obtained. Using our Doppler Echo CO Calculator, with HR 115 bpm:
  • LVOT CSA = 3.14 cm²
  • SV = 3.14 cm² × 12 cm = 37.7 mL
  • CO = 37.7 mL × 115 bpm = 4335 mL/min ≈ 4.3 L/min
  • Assuming BSA of 1.8 m², CI ≈ 2.4 L/min/m².

Interpretation & Impact:
The low-normal CO/CI in the context of hypotension and hyperdynamic LV with small IVC strongly suggests hypovolemic or distributive shock, rather than cardiogenic shock from primary pump failure. This directed immediate aggressive fluid resuscitation. Further workup revealed a urinary tract infection, and the patient was diagnosed with septic shock with a significant hypovolemic component. The early CO assessment helped guide appropriate initial therapy. More on CO in clinical settings.

Case Study 2: Acute Decompensated Heart Failure in the ICU

Patient Profile: A 65-year-old female with known HFrEF (EF 25%) admitted to ICU for worsening dyspnea, orthopnea, and anasarca. BP 90/60 mmHg, HR 95 bpm, on IV furosemide.

CO Measurement (Thermodilution via PAC):

• A PAC is placed due to poor response to initial diuretics and borderline perfusion.
• Thermodilution CO measured at 2.8 L/min. BSA is 1.6 m².
• CI = 2.8 L/min / 1.6 m² = 1.75 L/min/m².
• PCWP is 28 mmHg. SVR calculated as high. CPO calculated using our CPO calculator is very low (e.g., 0.45 W).

Interpretation & Impact:
The extremely low CI and CPO with high PCWP confirmed severe cardiogenic shock (“cold and wet” profile). This guided the decision to initiate inotropic support (e.g., dobutamine) in addition to continued diuresis. Serial CO/CI measurements then tracked response to therapy, aiming for a CI > 2.2 L/min/m² and CPO > 0.6 W. This illustrates how CO helps manage complex cardiac conditions like heart failure.

Case Study 3: Post-Operative Hypotension after Cardiac Surgery

Patient Profile: A 58-year-old male, 6 hours post-CABG surgery, develops hypotension (MAP 55 mmHg) despite adequate CVP. HR is 100 bpm.

CO Measurement (Continuous Pulse Contour Analysis – e.g., FloTrac):

• CO initially was 5.0 L/min, CI 2.8 L/min/m².
• Over 30 minutes, CO trended down to 3.5 L/min, CI to 1.9 L/min/m². SVV is low (e.g., 8%).

Interpretation & Impact:
The drop in CO/CI despite “adequate” CVP (which can be misleading post-cardiac surgery) and low SVV (suggesting not fluid responsive) raised concern for cardiac tamponade or acute graft failure. An urgent bedside echocardiogram was performed, revealing a small pericardial effusion but, more importantly, regional wall motion abnormalities in the territory of one of the grafts. This prompted urgent re-evaluation by the surgical team and consideration for return to OR or angiography. The continuous CO monitoring provided early warning of deteriorating cardiac function. Learn about advanced monitoring techniques here.

Case Study 4: Assessing Shunt in a Child with ASD

Patient Profile: A 5-year-old girl with a systolic murmur and exertional dyspnea. Echocardiogram suggests a moderate-sized atrial septal defect (ASD).

CO Measurement (Fick Method during Cardiac Catheterization):

• Oxygen saturations taken from SVC (venous inflow), pulmonary artery (mixed venous pre-shunt), femoral artery (systemic arterial), and pulmonary vein (if accessible, or assumed 98-100%). VO₂ is estimated.
• Pulmonary Blood Flow (Qp) calculated using PA and PV/FA O₂ content.
• Systemic Blood Flow (Qs) calculated using FA and SVC O₂ content.
  
  (Calculations use principles from our Fick calculator page).
• Results:

   

   

Interpretation & Impact:
The Qp:Qs ratio of 2:1 confirmed a hemodynamically significant left-to-right shunt, indicating that pulmonary blood flow was twice that of systemic blood flow. This data, along with echo findings and clinical symptoms, supported the decision for ASD closure. More on specific pediatric CO considerations.

Learning Points from Case Studies

• Cardiac output measurements provide objective data that can significantly refine clinical judgment.
• The trend of CO/CI is often more important than a single value.
• CO must always be interpreted in the context of other hemodynamic parameters (BP, HR, CVP, PCWP, SVR) and the overall clinical picture.
• Different CO measurement techniques are suited to different clinical scenarios and patient populations. Check our calculator comparison for guidance.

These cases highlight the practical power of cardiac output assessment. For further learning, consult resources from medical societies like the American College of Cardiology or ESICM for case reports and educational materials.

Many common questions about CO are also answered on our site.