Fig. 5

Effect of the combination of vitamins C and E on the duration of ventilation by the duration of ventilation in the control group. The diagonal line shows the meta-regression line based on the vitamin C alone trials from Fig. 4. The horizontal dashed line indicates the null effect. The results of the three trials [29,30,31] and their 95% CIs are shown. For calculations, see Additional file 2. RoM ratio of means [22]