 Statistical Analysis: A power analysis of the previously reported Stanford human volunteer study data was performed in order to estimate appropriate sample sizes. To estimate worst-case conditions, the measured parameter demonstrating greatest variation, MDPE, was selected. Assuming comparison with a two-sample, two-tailed t-test and a p-value of 0.05, a single-group sample size of 25 produced statistical power values of 1.0. Given this size, we can detect a 10 difference in MDPE under standard deviations of up to 7 and still maintain power values 0.85; thus, we selected n25 for each of the three study groups, yielding a total sample size of 75. We acknowledge that this sample size might prove to be over-powered; however, intraoperative study is known to be challenging. For example, all of the measured variables should not be expected to demonstrate normal distributions a critical assumption in the above power analysis, and we anticipate limited occurrence of confounding influences, such as protocol deviations and interruptions in data collection. Given the vagaries of intraoperative study, the chosen sample size of 75 patients seems reasonable. 