Detection and quantification of intraperitoneal fluid using electrical impedance tomography.

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Critical Care Medicine

Background:

• Intraperitoneal bleeding is a serious complication in patients undergoing continuous ambulatory peritoneal dialysis (CAPD).
• Accurate and timely detection of intraperitoneal bleeding is crucial for effective patient management.
• Existing methods for detecting intraperitoneal bleeding may have limitations in sensitivity or invasiveness.

Purpose of the Study:

• To evaluate a prototype electrical impedance tomography (EIT) system for detecting intraperitoneal bleeding.
• To assess the system's sensitivity and accuracy in quantifying fluid accumulation within the abdominal cavity.
• To investigate the impact of physiological factors and fluid location on EIT system performance.

Main Methods:

• A prototype EIT system was tested using patients undergoing CAPD.
• The system's ability to detect small amounts of dialysis fluid was assessed.
• A post-reconstructive filter was employed to ensure uniform sensitivity to blood across the abdominal cavity.
• The resistivity index was used to quantify fluid volume, and the system's response to fluid introduced outside the electrode plane was evaluated.

Main Results:

• The EIT system successfully detected small volumes of dialysis fluid with high sensitivity.
• A post-reconstructive filter achieved uniform sensitivity to anomalies regardless of their radial position.
• The resistivity index showed a near-linear relationship with the added fluid volume.
• System sensitivity was reduced by approximately half when fluid was introduced outside the electrode plane (e.g., in the stomach).
• Breathing artifacts interfered with quantitative monitoring on short timescales but were less significant compared to fluid administration rates.

Conclusions:

• The evaluated EIT system shows promise for detecting and monitoring intraperitoneal bleeding in CAPD patients.
• The system's sensitivity and quantitative capabilities are influenced by fluid location and physiological artifacts like breathing.
• Further refinement may be needed to mitigate the effects of breathing artifacts for long-term monitoring.