Summary of findings for the main comparison. Buffered versus non‐buffered crystalloid intravenous fluid for adults undergoing any form of surgery.
| Buffered versus non‐buffered crystalloid intravenous fluid for adults undergoing any form of surgery | ||||||
| Patient or population: adults receiving intravenous fluids whilst undergoing any form of surgery Setting: elective, major surgery in hospitals in Europe, USA, Asia, and the Middle East Intervention: buffered crystalloid intravenous fluid Comparison: non‐buffered crystalloid intravenous fluid | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | No. of participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Risk with non‐buffered fluid | Risk with buffered fluid | |||||
| Mortality (in‐hospital death and 30‐day mortality) | Study population | OR 1.85 (0.37 to 9.33) | 267 (3 RCTs) | ⊕⊕⊕⊝ LOWa | ||
| 15 per 1000 | 28 per 1000 (6 to 126) | |||||
| Organ system failure ‐ renal insufficiency requiring support | Study population | OR 0.82 (0.34 to 1.98) | 267 (4 RCTs) | ⊕⊕⊝⊝ LOWb | ||
| 92 per 1000 | 77 per 1000 (33 to 168) | |||||
| Plasma pH ‐ postoperative pH | Mean postoperative pH was 7.32. | Mean postoperative pH in intervention group was 0.05 higher (0.04 to 0.07). | ‐ | 720 (12 RCTs) | ⊕⊕⊕⊝ MODERATEc | |
| Serum chloride (mmol/L) ‐ postoperative chloride | Mean postoperative chloride was 114.3 mmol/L. | Mean postoperative chloride in intervention group was 6.77 mmol/L lower (3.38 to 10.17). | ‐ | 530 (10 RCTs) | ⊕⊕⊕⊝ MODERATEd | |
| *The risk in the intervention group (and its 95% confidence interval) is based on assumed risk in the comparison group and relative effect of the intervention (and its 95% CI). CI: confidence interval; OR: odds ratio; RR: risk ratio. | ||||||
| GRADE Working Group grades of evidence. High quality: We are very confident that the true effect lies close to that of the estimate of the effect. Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect. Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect. | ||||||
aDowngraded ‐2. Data from 3 studies only with few events. All 3 studies have unclear risk of bias for outcome assessment. Waters et al. also has unclear risk of reporting bias and attrition bias. Overall confidence in the effect estimate is low.
bDowngraded ‐2. Half of studies included patients with the confounding effect of existing organ failure, i.e. participants undergoing renal transplant for renal failure. All studies had unclear risk of detection bias. 2 studies had unclear risk of reporting bias. 2 studies had unclear risk of attrition bias.
cDowngraded ‐1. Significant heterogeneity in methods, included participant characteristics, and outcomes between studies. Small numbers of participants in each trial.
dDowngraded ‐1. Significant heterogeneity in methods, included participant characteristics, and outcomes between studies.