Primary Outcome measures
Meta-analytic estimate showed that a positive trend towards preventing acute kidney injury in patients treated with NAC. There was moderate statistical heterogeneity (I2= 31%) among the studies for any of the primary outcomes. Overall results showed that the effect of NAC in preventing acute kidney injury after adult cardiac surgery was controversial, as showed in Fig 2 (OR: 0.84, 95% CI: 0.64-1.10). As such, overall meta analytic estimates showed that NAC did not have a significant effect, however 1 study showed that NAC had significant benefits.
Perioperative usage of N-acetylcysteine was examined in 5 studies. Intraoperative to postoperative usage of NAC was examined in 5 studies where NAC was administered after the induction of anaesthesia and administered for 12 to 24hrs post operatively. Meta-analytic estimates of perioperative usage and intraoperative to postoperative usage are detailed in Fig 3 and Fig 4.
High dosage of NAC was administered in 5 studies, where generally, the dosage administered was 150mg/kg for 15 minutes, 50mg/kg for the next 4 hours, and 100 mg/kg for the next 16 to 20 hours. Low dosage of NAC was administered in 5 studies, where the total dosage administered ranged from 2400ml to 8400ml. The format of the dosages reported varied depending on the study. These characteristics of the studies are summarized in Supplemental Table 3. Meta-analytic estimates of high dosage and low dosage of NAC administered are detailed in Fig 5 and Fig 6.