Non-invasive and invasive measurement of skeletal muscular oxygenation during isolated limb perfusion

Background: Isolated limb perfusion (ILP) is a regional surgical treatment for localized metastatic disease. High doses of chemotherapeutic agents are administered within an extracorporeal circulated isolated extremity, treating the metastasis, while systemic toxicity is avoided. To our knowledge, indexed oxygen supply/demand relationship during ILP has not previously been described. Our aim was to measure and describe oxygen metabolism, specifically oxygen delivery, consumption, and extraction, in an isolated leg/arm during ILP. Also investigate whether invasive oxygenation measurement during ILP correlates and can be used interchangeable with the non-invasive method, near infrared spectroscopy (NIRS). Methods: Data from 40 patients scheduled for ILP were included. At six time points blood samples were drawn during the procedure. DO2, VO2, and O2ER were calculated according to standard formulas. NIRS and hemodynamics were recorded every 10 min. Results: For all observations, the mean of DO2 was 190 +/- 59 ml/min/m(2), VO2 was 35 +/- 8 ml/min/m(2), and O2ER was 21 +/- 8%. VO2 was significantly higher in legs compared to arms (38 +/- 8 vs. 29 +/- 7 ml/min/m(2), p=0.02). Repeated measures showed a significant decrease in DO2 in legs (209 +/- 65 to 180 +/- 66 ml/min/m(2), p=<0.01) and in arms (252 +/- 72 to 150 +/- 57 ml/min/m(2), p=<0.01). Significant increase in O2ER in arms was also found (p=0.03). Significant correlation was detected between NIRS and venous extremity oxygen saturation (SveO(2)) (r rm=0.568, p=<. 001, 95% CI 0.397-0.701). When comparing SveO(2) and NIRS using a Bland-Altman analysis, the mean difference (bias) was 8.26 +/- 13.03 (p=<. 001) and the limit of agreement was - 17.28-33.09, with an error of 32.5%. Conclusion: DO2 above 170 ml/min/m(2) during ILP kept O2ER below 30% for all observations. NIRS correlates significant to SveO(2); however, the two methods do not agree sufficiently to work interchangeable.