Efficacy and safety of carbon dioxide insufflation for brain protection for patients undergoing planned left-sided open heart valve surgery: protocol for a multicentre, placebo-con... by Todd, R, Rogers, CA, Pufulete, M, Culliford, L, Pretorius, P, Voets, N, Akowuah, E, Sayeed, R, Lazaroo, M, Kaur, S, Angelini, GD, Gibbison, B