[Impedance cardiography following cardiac surgery]

Area of Science:

• Cardiology
• Medical Engineering
• Intensive Care Medicine

Background:

• Postoperative monitoring of cardiac surgery patients is crucial for managing hemodynamic stability.
• Extracorporeal circulation can significantly alter fluid balance and cardiac function.
• Non-invasive monitoring methods are desirable for intensive care settings.

Purpose of the Study:

• To evaluate the feasibility and accuracy of impedance cardiography (ICG) for monitoring intensive care patients after cardiac surgery.
• To compare ICG-derived stroke volumes with thermodilution measurements.
• To assess the utility of ICG parameters for postoperative management.

Main Methods:

• Ten patients undergoing cardiac surgery with extracorporeal circulation were monitored.
• Stroke volumes were measured using both thermodilution and ICG.
• Cardiac output, HEATHER-index, dZ/dt, and thoracic impedance were recorded preoperatively and up to two days postoperatively.

Main Results:

• ICG showed a strong correlation with thermodilution for stroke volume (r = 0.933).
• Cardiac output decreased post-surgery but recovered to 94% of preoperative values by day two.
• Thoracic impedance decreased by over 20% after surgery, indicating fluid shifts.

Conclusions:

• Impedance cardiography is a viable tool for monitoring stroke volume and cardiac output in intensive care post-cardiac surgery.
• ICG parameters like HEATHER-index and dZ/dt are useful for quantitative treatment control.
• Continuous thoracic impedance monitoring aids in assessing pulmonary hydration and fluid balance.