Kaplan-Meier curves depicting the probability of survival from study enrollment in patients receiving conventional chest physical therapy (CCPT) (solid line) and patients receiving high-frequency chest-wall compressions (HFCWCs) (dashed line) (P = .14 by log rank test).HFCWC. Kaplan-Meier curves depicting the probability of survival from study enrollment in patients receiving conventional chest physical therapy (CCPT) (solid line) and patients receiving high-frequency chest-wall compressions (HFCWCs) (dashed line) (P = .14 by log rank test).HFCWC Darnetta Clinkscale et al. Respir Care 2012;57:221-228 (c) 2012 by Daedalus Enterprises, Inc.