| Trial [ref.] | N | Setting | Vitamin C | Length of mechanical ventilation (hours) | RoM |
|---|
| Route | Dose (g/day) | Vitamin C | Control | |
|---|
| | | Mean | SD | Mean | SD | |
|---|
| Bjordahl et al. [11] | 185 | Cardiac | po | 2 | 28.8 | 19.2 | 33.6 | 24.0 | 0.86 |
| Amini et al. [12] | 137 | Cardiac | po | 3 | 7.3 | 6.0 | 6.7 | 4.3 | 1.10 |
| Dehghani et al .[13] | 100 | Cardiac | po | 1 | 13.4 | 2.0 | 15.4 | 14.3 | 0.87 |
| Habib et al. [14] | 100 | Sepsis | iv | 6 | 110 | 50 | 189 | 72 | 0.58 |
| Safaei et al. [15] | 58 | Cardiac | iv | 2 | 15.1 | 5.39 | 22.9 | 20.46 | 0.66 |
| Ebade et al. [16] | 40 | Cardiac | iv | 3 | 2.04 | 0.35 | 1.99 | 0.31 | 1.02 |
| Tanaka et al. [17] | 37 | Burns | iv | 90* | 290 | 211 | 511 | 374 | 0.57 |
| Zabet et al. [18] | 28 | Sepsis | iv | 6* | 36.6 | 16.1 | 46.8 | 10.1 | 0.78 |
| Sadeghpour et al. [19]** | 290 | Cardiac | po | 1 | 11.8 | 3.9 | 14.1 | 9.5 | 0.84 |
- The trials are listed by the number of patients (N). The mean age in the trials ranged from 42 to 64 years, with a median of 60 years. The proportion of males varied from 58% to 75%. Five trials were carried out in Iran [12, 13, 15, 18, 19], two in Egypt [14, 16], one in the USA [11], and one in Japan [17]. For detailed descriptions of the trials, see Additional file 1: Table S1. The Amini trial [12] results are modified as described previously [1]
- *Estimated vitamin C dose, see the “Methods” section
- **Sadeghpour et al. [19] recruited 500 participants but reported the results for just 290 participants [1]. Because of the high dropout rate (42%), we did not include this trial in our calculations, but we overlay the findings in Fig. 4
- iv intravenous, po per oral, RoM ratio of means [22]: e.g., for the Bjordahl trial [11], RoM = 0.86, based on 28.8/33.6, and RoM = 0.86 indicates that ventilation time in the vitamin C group was 14% shorter than in the placebo group
