DATA SOURCES: Systematic search of MEDLINE, EMBASE, CINAHL, and the Cochrane Register of Controlled Trials.

STUDY SELECTION: Randomized controlled trials testing IV vitamin C in critically ill patients.

DATA ABSTRACTION: Two independent reviewers abstracted patient characteristics, treatment details, and clinical outcomes.

DATA SYNTHESIS: Fifteen studies involving 2,490 patients were identified. Compared with placebo, IV vitamin C administration is associated with a trend toward reduced overall mortality (relative risk, 0.87; 95% CI, 0.75-1.00; p = 0.06; test for heterogeneity I2 = 6%). High-dose IV vitamin C was associated with a significant reduction in overall mortality (relative risk, 0.70; 95% CI, 0.52-0.96; p = 0.03), whereas low-dose IV vitamin C had no effect (relative risk, 0.94; 95% CI, 0.79-1.07; p = 0.46; test for subgroup differences, p = 0.14). IV vitamin C monotherapy was associated with a significant reduction in overall mortality (relative risk, 0.64; 95% CI, 0.49-0.83; p = 0.006), whereas there was no effect with IV vitamin C combined therapy. No trial reported an increase in adverse events related to IV vitamin C.

METHODS: RCTs that compared probiotics or synbiotics to usual care or placebo and reported clinical and diarrheal outcomes were searched in 4 electronic databases from inception to March 8, 2022 without language restriction. Four reviewers independently extracted data and assessed the study qualities using the Critical Care Nutrition (CCN) Methodological Quality Scoring System. Random-effect meta-analysis and trial sequential analysis (TSA) were used to synthesize the results. The primary outcome was ventilator-associated pneumonia (VAP). The main subgroup analysis compared the effects of higher versus lower quality studies (based on median CCN score).

RESULTS: Seventy-five studies with 71 unique trials (n = 8551) were included. In the overall analysis, probiotics significantly reduced VAP incidence (risk ratio [RR] 0.70, 95% confidence interval [CI] 0.56-0.88; I2 = 65%; 16 studies). However, such benefits were demonstrated only in lower (RR 0.47, 95% CI 0.32, 0.69; I2 = 44%; 7 studies) but not higher quality studies (RR 0.89, 95% CI 0.73, 1.08; I2 = 43%; 9 studies), with significant test for subgroup differences (p = 0.004). Additionally, TSA showed that the VAP benefits of probiotics in the overall and subgroup analyses were type-1 errors. In higher quality trials, TSA found that future trials are unlikely to demonstrate any benefits of probiotics on infectious complications and diarrhea. Probiotics had higher adverse events than control (pooled risk difference: 0.01, 95% CI 0.01, 0.02; I2 = 0%; 22 studies).

CONCLUSION: High-quality RCTs did not support a beneficial effect of probiotics on clinical or diarrheal outcomes in critically ill patients. Given the lack of benefits and the increased incidence of adverse events, probiotics should not be routinely administered to critically ill patients.

METHODS: In this international, prospective cohort study of 15,065 patients aged 45 yr or older who underwent in-patient noncardiac surgery, troponin T was measured during the first 3 postoperative days. Patients with a troponin T level of 0.04 ng/ml or greater (elevated "abnormal" laboratory threshold) were assessed for ischemic features (i.e., ischemic symptoms and electrocardiography findings). Patients adjudicated as having a nonischemic troponin elevation (e.g., sepsis) were excluded. To establish diagnostic criteria for MINS, the authors used Cox regression analyses in which the dependent variable was 30-day mortality (260 deaths) and independent variables included preoperative variables, perioperative complications, and potential MINS diagnostic criteria.

RESULTS: An elevated troponin after noncardiac surgery, irrespective of the presence of an ischemic feature, independently predicted 30-day mortality. Therefore, the authors' diagnostic criterion for MINS was a peak troponin T level of 0.03 ng/ml or greater judged due to myocardial ischemia. MINS was an independent predictor of 30-day mortality (adjusted hazard ratio, 3.87; 95% CI, 2.96-5.08) and had the highest population-attributable risk (34.0%, 95% CI, 26.6-41.5) of the perioperative complications. Twelve hundred patients (8.0%) suffered MINS, and 58.2% of these patients would not have fulfilled the universal definition of myocardial infarction. Only 15.8% of patients with MINS experienced an ischemic symptom.