Preliminary assessment of abdominal organ perfusion utilizing a fiber optic photoplethysmographic sensor

In an attempt to overcome the limitations of current techniques for monitoring abdominal organ perfusion, a prototype reflectance fiber optic photoplethysmographic (PPG) sensor and processing system was evaluated on seventeen anaesthetized patients undergoing laparotomy. Good quality PPG signals were obtained from the large bowel, small bowel, liver and stomach. Simultaneous PPG signals from the finger were also obtained for comparison purposes using an identical fiber optic sensor. Analysis of the mean ac and dc PPG amplitudes of all acquired signals indicated larger amplitudes for those signals obtained from abdominal organs than those obtained from the finger. Mean estimated blood oxygen saturation (SpO₂) values from all abdominal sites showed good agreement with those obtained from the finger using both the finger fiber optic sensor and a commercial finger pulse oximeter. Furthermore, a Bland and Altman between-method-differences analysis on the estimated SpO₂ data suggests that a fiber optic abdominal sensor may be a suitable method for the evaluation of abdominal organ perfusion.