Low-Protein, Hypocaloric Nutrition with Glutamine versus Full-Feeding in the Acute Phase in ICU Patients with Severe Traumatic Brain Injury

No benefit of higher protein dosing in critically ill patients: a systematic review and meta-analysis of randomized controlled trials

Purpose

The optimal range of protein dosage and effect of high-dose protein on critically ill patients remain controversial. We conducted a meta-analysis to compare higher and lower doses of protein supplementation for nutritional support in critically ill patients.

Methods

We searched the PubMed, Embase, Scopus, and Cochrane Library databases for randomized controlled trials that compared higher (≥1.2 g/kg per day) versus lower (<1.2 g/kg per day) doses of protein supplementation among critically ill adult patients. This search spanned from the inception of relevant databases to November 20, 2023. Our primary endpoint of interest was overall mortality, while secondary endpoints included length of stay in the intensive care unit, length of hospital stay, duration of mechanical ventilation, and incidence of acute kidney injury.

Results

Seventeen studies including 2,965 critically ill patients were included in our meta-analysis. The pooled analyses showed no significant difference in overall mortality (RR 1.03, 95%CI [0.92-1.15], P = 0.65, I2 = 0%), length of intensive care unit stay (MD 0.19, 95%CI [-0.67 to 1.04], P = 0.66, I2 = 25%), length of hospital stay (MD 0.73, 95%CI [-1.59 to 3.04], P = 0.54, I2 = 27%), duration of mechanical ventilation (MD -0.14, 95%CI [-0.83 to 0.54], P = 0.68, I2 = 8%), and incidence of acute kidney injury (RR 1.11, 95%CI [0.87-1.41], P = 0.38, I2 = 0%) between critically ill patients receiving higher or lower doses of protein supplementation.

Conclusions

For critically ill patients, the protein supplementation dose had no significant effect on clinical outcomes, including overall mortality, length of intensive care unit and hospital stay, duration of mechanical ventilation, and incidence of acute kidney injury.

Efficacy of permissive underfeeding for critically ill patients: an updated systematic review and trial sequential meta-analysis

BACKGROUND

Our previous study in 2011 concluded that permissive underfeeding may improve outcomes in patients receiving parenteral nutrition therapy. This conclusion was tentative, given the small sample size. We conducted the present systematic review and trial sequential meta-analysis to update the status of permissive underfeeding in patients who were admitted to the intensive care unit (ICU).

METHODS

Seven databases were searched: PubMed, Embase, Web of Science, China National Knowledge Infrastructure, Wanfang, Chinese Biomedical Literature Database, and Cochrane Library. Randomized controlled trials (RCTs) were included. The Revised Cochrane risk-of-bias tool (ROB 2) was used to assess the risk of bias in the enrolled trials. RevMan software was used for data synthesis. Trial sequential analyses (TSA) of overall and ICU mortalities were performed.

RESULTS

Twenty-three RCTs involving 11,444 critically ill patients were included. There were no significant differences in overall mortality, hospital mortality, length of hospital stays, and incidence of overall infection. Compared with the control group, permissive underfeeding significantly reduced ICU mortality (risk ratio [RR] = 0.90; 95% confidence interval [CI], [0.81, 0.99]; P = 0.02; I2 = 0%), and the incidence of gastrointestinal adverse events decreased (RR = 0.79; 95% CI, [0.69, 0.90]; P = 0.0003; I2 = 56%). Furthermore, mechanical ventilation duration was reduced (mean difference (MD) = - 1.85 days; 95% CI, [- 3.44, - 0.27]; P = 0.02; I2 = 0%).

CONCLUSIONS

Permissive underfeeding may reduce ICU mortality in critically ill patients and help to shorten mechanical ventilation duration, but the overall mortality is not improved. Owing to the sample size and patient heterogeneity, the conclusions still need to be verified by well-designed, large-scale RCTs. Trial Registration The protocol for our meta-analysis and systematic review was registered and recorded in PROSPERO (registration no. CRD42023451308). Registered 14 August 2023.

High protein provision of more than 1.2 g/kg improves muscle mass preservation and mortality in ICU patients: A systematic review and meta-analyses

BACKGROUND

ICU patients lose muscle mass rapidly and maintenance of muscle mass may contribute to improved survival rates and quality of life. Protein provision may be beneficial for preservation of muscle mass and other clinical outcomes, including survival. Current protein recommendations are expert-based and range from 1.2 to 2.0 g/kg. Thus, we performed a systematic review and meta-analysis on protein provision and all clinically relevant outcomes recorded in the available literature.

METHODS

We conducted a systematic review and meta-analyses, including studies of all designs except case control and case studies, with patients aged ≥18 years with an ICU stay of ≥2 days and a mean protein provision group of ≥1.2 g/kg as compared to <1.2 g/kg with a difference of ≥0.2 g/kg between protein provision groups. All clinically relevant outcomes were studied. Meta-analyses were performed for all clinically relevant outcomes that were recorded in ≥3 included studies.

RESULTS

A total of 29 studies published between 2012 and 2022 were included. Outcomes reported in the included studies were ICU, hospital, 28-day, 30-day, 42-day, 60-day, 90-day and 6-month mortality, ICU and hospital length of stay, duration of mechanical ventilation, vomiting, diarrhea, gastric residual volume, pneumonia, overall infections, nitrogen balance, changes in muscle mass, destination at hospital discharge, physical performance and psychological status. Meta-analyses showed differences between groups in favour of high protein provision for 60-day mortality, nitrogen balance and changes in muscle mass.

CONCLUSION

High protein provision of more than 1.2 g/kg in critically ill patients seemed to improve nitrogen balance and changes in muscle mass on the short-term and likely 60-day mortality. Data on long-term effects on quality of life are urgently needed.

Effect of glutamine supplementation on inflammatory markers in critically ill patients supported with enteral or parenteral feeding

BACKGROUND

Glutamine plays an important role in acute catabolic conditions in critically ill patients. This meta-analysis aimed to investigate the effect of glutamine supplementation on inflammatory markers in critically ill patients supported with enteral feeding (EN) or parenteral feeding (PN).

METHODS

PubMed, Web of Science, Scopus, and Embase were explored to identify the studies investigating the effect of glutamine on serum inflammatory markers in intensive care unit patients. All randomized clinical trials that assessed the effect of glutamine supplementation on "inflammatory markers" in EN or PN were included in the study. Because a small number of studies were included, SE was adjusted for overall effect size by using the Knapp-Hartung method.

RESULTS

In this study, 2728 eligible studies were initially included, and 10 eligible case-control studies were finally enrolled for further investigations. There was a statistical reduction between preintervention and postintervention CRP levels (standardized mean difference [SMD] = -0.38 mg/L; 95% CI, -0.72 to -0.03). No significant association was found between L-glutamine supplementation in the EN/PN and interleukin 6 (IL-6) (SMD = -0.58 pg/ml; 95% CI, -2.15 to 0.99) and tumor necrosis factor alpha (TNF-α) (SMD = 2.69 pg/ml; 95% CI, -9.66 to 15.03) compared with the control group.

CONCLUSIONS

This study identified that glutamine supplementation might have an important effect on CRP in acute conditions and no significant effect on IL-6 and TNF-α in acute conditions.