In the history of CICM exams, this has only come up once: in Question 23 from the second paper of 2008, where we were called upon to define the types of error.
There is an online Handbook of Biological Statistics which has an excellent overview of power analysis.
Kelley, Ken, and Kristopher J. Preacher. "On effect size." Psychological methods 17.2 (2012): 137.
Moher, David, Corinne S. Dulberg, and George A. Wells. "Statistical power, sample size, and their reporting in randomized controlled trials." Jama 272.2 (1994): 122-124.
Cohen, Jacob. "A power primer." Psychological bulletin 112.1 (1992): 155.
Dupont, William D., and Walton D. Plummer Jr. "Power and sample size calculations: a review and computer program." Controlled clinical trials 11.2 (1990): 116-128.
Eng, John. "Sample Size Estimation: How Many Individuals Should Be Studied? 1." Radiology 227.2 (2003): 309-313.