Measurement of intestinal edema using an impedance analyzer circuit.
BACKGROUND
Acute intestinal edema adversely affects intestinal transit, permeability, and contractility. Current resuscitation modalities, while effective, are associated with development of acute intestinal edema. Knowledge of levels of tissue edema would allow clinicians to monitor intestinal tissue water and may help prevent the detrimental effects of edema. However, there is no simple method to measure intestinal tissue water without biopsy. We sought to develop a tissue impedance analyzer to measure tissue edema, without the need for invasive biopsy.


METHODS
Oscillating voltage input was applied to the analyzer circuit and an oscilloscope measured the voltage output across any load. Rats were randomized to three groups: sham, mild edema (80 mL/kg of NS resuscitation), and severe edema (80 mL/kg of NS resuscitation with intestinal venous hypertension). Intestinal edema was measured by wet-to-dry tissue weight ratio. Bowel impedance was measured and converted to capacitance using a standard curve.


RESULTS
Acute intestinal edema causes a significant increase in bowel capacitance. This capacitance can be used to predict tissue water concentration.


CONCLUSIONS
Using an impedance analyzer circuit, it is possible to measure intestinal edema reliably and quickly. This may prove to be a useful tool in the resuscitation of critically ill patients.
Radhakrishnan
Ravi S
RS
Department of Surgery, University of Texas-Houston Medical School, Houston, Texas 77030, USA.
Shah
Kunal
K
Xue
Hasen
H
Moore-Olufemi
Stacey D
SD
Moore
Frederick A
FA
Weisbrodt
Norman W
NW
Allen
Steven J
SJ
Gill
Brijesh
B
Cox
Charles S
CS
D000208:Acute Disease; D000818:Animals; D004487:Edema / Q000175:diagnosis* / Q000503:physiopathology; D025802:Electric Capacitance; D017097:Electric Impedance; D004582:Electronics, Medical / Q000295:instrumentation* / Q000379:methods* / Q000592:standards; D004867:Equipment Design; D007422:Intestines / Q000473:pathology / Q000503:physiopathology*; D008297:Male; D009929:Organ Size; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012720:Severity of Illness Index