Data Analysis
The total number of procedures completed in each equivalent time frame
were compared to determine the difference between procedure volumes
accomplished with proactive cooling and without it. Statistical
significance of the increase in rate was assessed assuming that the
number of procedures before and after cooling followed the Poisson
distribution with equal rate parameters; we used the two-sided level
0.05 exact test implemented via the poisson.test function in R. This
function also provided a 95% confidence interval (CI) for the rate
ratio.