Figure 1

Probability of death as a function of oxygen debt. (a) Regression-derived relation of Kaplan–Meier probability of death as a function of increasing oxygen debt (O₂D) in a canine O₂D hemorrhagic shock model. Noted on the figure are the O₂D values for lethal dose (LD)₂₅ (i.e. a dose sufficient to kill 25% of the population studied), LD₅₀, and LD₇₅ probabilities. Points plotted along the regression line and its 95% confidence limits represent the actual Kaplan–Meier survival (S) values at 60 min of hemorrhage, or values at the time of death (D) for nonsurviving animals dying during the hemorrhage period or within 5 min of the 60 min hemorrhage sample. Note the good correlation of Kaplan–Meier points to the regression-estimated line. Reproduced with permission from Dunham and coworkers [9]. (b) Probability of death as a function of O₂D in a pig O₂D hemorrhagic shock model. Noted on the figure are the O₂D values for LD₂₅, LD₅₀, and LD₇₅ probabilities. Points plotted along the regression line and its 95% confidence limits represent the values of cumulative O₂D (in ml/kg) at 60 min of hemorrhage for survivors (marked with circles) and nonsurvivors (marked with squares). Modified from Rixen and coworkers [44].