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.

Nutritional support in sepsis: when less may be more

Despite sound basis to suspect that aggressive and early administration of nutritional support may hold therapeutic benefits during sepsis, recommendations for nutritional support have been somewhat underwhelming. Current guidelines (ESPEN and ASPEN) recognise a lack of clear evidence demonstrating the beneficial effect of nutritional support during sepsis, raising the question: why, given the perceived low efficacy of nutritionals support, are there no high-quality clinical trials on the efficacy of permissive underfeeding in sepsis? Here, we review clinically relevant beneficial effects of permissive underfeeding, motivating the urgent need to investigate the clinical benefits of delaying nutritional support during sepsis.

Metabolic support in the critically ill: a consensus of 19

Metabolic alterations in the critically ill have been studied for more than a century, but the heterogeneity of the critically ill patient population, the varying duration and severity of the acute phase of illness, and the many confounding factors have hindered progress in the field. These factors may explain why management of metabolic alterations and related conditions in critically ill patients has for many years been guided by recommendations based essentially on expert opinion. Over the last decade, a number of randomized controlled trials have been conducted, providing us with important population-level evidence that refutes several longstanding paradigms. However, between-patient variation means there is still substantial uncertainty when translating population-level evidence to individuals. A cornerstone of metabolic care is nutrition, for which there is a multifold of published guidelines that agree on many issues but disagree on others. Using a series of nine questions, we provide a review of the latest data in this field and a background to promote efforts to address the need for international consistency in recommendations related to the metabolic care of the critically ill patient. Our purpose is not to replace existing guidelines, but to comment on differences and add perspective.

Optimizing early enteral nutrition in severe stroke (OPENS): protocol for a multicentre randomized controlled trial

Background

Malnutrition is one of the crucial factors associated with poor prognosis in critical ill patients, yet a significant evidence gap surrounds the management of initial enteral feeding in severe stroke. The Optimizing Early Enteral Nutrition in Severe Stroke (OPENS) trial will compare a strategy of modified full enteral nutrition (EN) (standard full EN in conjunction with prokinetic drug) and a strategy of permissive underfeeding (40 to 60% of estimated caloric requirements) with standard full EN (advancement to target nutrition goals) in patients with severe stroke.

Methods

The OPENS trial is a multicenter randomized controlled study. A total of 600 adult patients with severe stroke will be enrolled in 12 study sites in China, and randomized to standard full EN, modified full EN, or permissive underfeeding. The primary outcome measurement is the proportion of participants with a poor outcome (modified Rankin Scale ≥3) at day 90 of enrollment. Secondary outcomes include incidence rates of complications during hospitalization, disability at hospital discharge, and the ability of activities of daily living at day 90 of enrollment. The relationship between intervention and the primary outcome will be analyzed using multivariate logistic regression adjusted for study site, demographics, and baseline characteristics.

Discussion

The OPENS trial will explore the optimum initial feeding strategy for acute severe stroke. This trial is, therefore, an important step in bridging the evidence gap surrounding the enteral feeding for patients with severe stroke during the first week of hospitalization.

Trial registration

ClinicalTrials.gov Identifier: NCT02982668; First Posted: December 5, 2016.

Critical Care Nutrition: Where's the Evidence?

The surgical critically ill patient is subject to a variable and complex metabolic response, which has detrimental effects on immunity, wound healing, and preservation of lean body muscle. The concept of nutrition support has evolved into nutrition therapy, whereby the primary objectives are to prevent oxidative cell injury, modulate the immune response, and attenuate the metabolic response. This review outlines the metabolic response to critical illness, describes nutritional risk; reviews the evidence for the role, dose, and timing of enteral and parenteral nutrition, and reviews the evidence for immunonutrition in the surgical intensive care unit.

Relationship of energy and protein adequacy with 60-day mortality in mechanically ventilated critically ill patients: A prospective observational study

BACKGROUND & AIMS

The effect of provision of full feeding or permissive underfeeding on mortality in mechanically ventilated critically ill patients in the intensive care unit (ICU) is still controversial. This study investigated the relationship of energy and protein intakes with 60-day mortality, and the extent to which ICU length of stay and nutritional risk status influenced this relationship.

METHODS

This is a prospective observational study conducted among critically ill patients aged ≥18 years, intubated and mechanically ventilated within 48 h of ICU admission and stayed in the ICU for at least 72 h. Information on baseline characteristics and nutritional risk status (the modified Nutrition Risk in Critically ill [NUTRIC] score) was collected on day 1. Nutritional intake was recorded daily until death, discharge, or until the twelfth evaluable days. Mortality status was assessed on day 60 based on the patient's hospital record. Patients were divided into 3 groups a) received <2/3 of prescribed energy and protein (both <2/3), b) received ≥2/3 of prescribed energy and protein (both ≥2/3) and c) either energy or protein received were ≥2/3 of prescribed (either ≥2/3). The relationship between the three groups with 60-day mortality was examined by using logistic regression with adjustment for potential confounders. Sensitivity analysis was performed to examine the influence of ICU length of stay (≥7 days) and nutritional risk status.

RESULTS

Data were collected from 154 mechanically ventilated patients (age, 51.3 ± 15.7 years; body mass index, 26.5 ± 6.7 kg/m²; 54% male). The mean modified NUTRIC score was 5.7 ± 1.9, with 56% of the patients at high nutritional risk. The patients received 64.5 ± 21.6% of the amount of energy and 56.4 ± 20.6% of the amount of protein prescribed. Provision of energy and protein at ≥2/3 compared with <2/3 of the prescribed amounts was associated with a trend towards increased 60-day mortality (Adjusted odds ratio [Adj OR] 2.23; 95% confidence interval [CI], 0.92-5.38; p = 0.074). No difference in mortality status was found between energy and protein provision at either ≥2/3 compared with <2/3 of the prescribed amounts (Adj OR 1.61, 95% CI, 0.58-4.45; p = 0.357). Nutritional risk status, not ICU length of stay, influenced the relationship between nutritional adequacy and 60-day mortality.

CONCLUSIONS

Energy and protein adequacy of ≥2/3 of the prescribed amounts were associated with a trend towards increased 60-day mortality among mechanically ventilated critically ill patients. However, neither energy nor protein adequacy alone at ≥ or <2/3 adequacy affect 60-day mortality. Increased mortality was associated with provision of energy and protein at ≥2/3 of the prescribed amounts, which only affected patients with low nutritional risk.

The Critical Care Obesity Paradox and Implications for Nutrition Support

Obesity is a leading cause of preventable death worldwide. The prevalence of obesity has been increasing and is associated with an increased risk for other co-morbidities. In the critical care setting, nearly one third of patients are obese. Obese critically ill patients pose significant physical and on-physical challenges to providers, including optimization of nutrition therapy. Intuitively, obese patients would have worse critical care-related outcome. On the contrary, emerging data suggests that critically ill obese patients have improved outcomes, and this phenomenon has been coined "the obesity paradox." The purposes of this review will be to outline the historical views and pathophysiology of obesity and epidemiology of obesity, describe the challenges associated with obesity in the intensive care unit setting, review critical care outcomes in the obese, define the obesity-critical care paradox, and identify the challenges and role of nutrition support in the critically ill obese patient.

Normocaloric versus hypocaloric feeding on the outcomes of ICU patients: a systematic review and meta-analysis

INTRODUCTION

Current clinical practice guidelines recommend providing ICU patients a daily caloric intake estimated to match 80-100 % of energy expenditure (normocaloric goals). However, recent clinical trials of intentional hypocaloric feeding question this approach.

METHODS

We performed a systematic review and meta-analysis to compare the outcomes of ICU patients randomized to intentional hypocaloric or normocaloric goals. We included randomized controlled trials that enrolled ICU patients and compared intentional hypocaloric with normocaloric nutritional goals. We included studies that evaluated both trophic feeding as well as permissive underfeeding. Data sources included MEDLINE, Cochrane Register of Controlled Trials and citation review of relevant primary and review articles. The outcomes of interest included hospital acquired infection, hospital mortality, ICU length of stay (LOS) and ventilator-free days (VFDs).

RESULTS

Six studies which enrolled 2517 patients met our inclusion criteria. The mean age and body mass index (BMI) across the studies were 53 ± 5 years and 29.1 ± 1.5 kg/m(2), respectively. Two studies compared normocaloric feeding (77% of goal) with trophic feeding (20% of goal), while four studies compared normocaloric feeding (72% of goal) with permissive underfeeding (49% of goal). Overall, there was no significant difference in the risk of infectious complications (OR 1.03; 95% CI 0.84-1.27, I(2) = 16%), hospital mortality (OR 0.91; 95% CI 0.75-1.11, I(2) = 8%) or ICU LOS (mean difference 0.05 days; 95% CI 1.33-1.44 days; I(2) = 37%) between groups. VFDs were reported in three studies with no significant difference between the normocaloric and intentional hypocaloric groups (data not pooled).

CONCLUSION

This meta-analysis demonstrated no difference in the risk of acquired infections, hospital mortality, ICU length of stay or ventilator-free days between patients receiving intentional hypocaloric as compared to normocaloric nutritional goals.

A single-blinded randomised clinical trial of permissive underfeeding in patients requiring parenteral nutrition

BACKGROUND & AIMS

The importance of adequate nutritional support is well established, but characterising what 'adequate nutrition' represents remains contentious. In recent years there has been increasing interest in the concept of 'permissive underfeeding' where patients are intentionally prescribed less nutrition than their calculated requirements. The aim of this study was to evaluate the effect of permissive underfeeding on septic and nutrition related morbidity in patients requiring short term parenteral nutrition (PN).

METHODS

This was a single-blinded randomised clinical trial of 50 consecutive patients requiring parenteral nutritional support. Patients were randomized to receive either normocaloric or hypocaloric feeding (respectively 100% vs. 60% of estimated requirements). The primary end point was septic complications. Secondary end points included the metabolic, physiological and clinical outcomes to the two feeding protocols.

RESULTS

Permissive underfeeding was associated with fewer septic complications (3 vs. 12 patients; p = 0.003), and a lower incidence of the systemic inflammatory response syndrome (9 vs. 16 patients; p = 0.017). Permissively underfed patients had fewer feed related complications (2 vs. 9 patients; p = 0.016).

CONCLUSION

Permissive underfeeding in patients requiring short term PN appears to be safe and may results in reduced septic and feed-related complications.

TRIAL REGISTRATION

NCT01154179 TRIAL REGISTRY: http://clinicaltrials.gov/ct2/show/NCT01154179.

Key details of the duodenal-jejunal bypass in type 2 diabetes mellitus rats

AIM: To investigate which surgical techniques and perioperative regimens yielded the best survival rates for diabetic rats undergoing gastric bypass.

METHODS: We performed Roux-en-Y gastric bypass with reserved gastric volume, a procedure in which gastrointestinal continuity was reestablished while excluding the entire duodenum and proximal jejunal loop. We observed the procedural success rate, long-term survival, and histopathological sequelae associated with a number of technical modifications. These included: use of anatomical markers to precisely identify Treitz’s ligament; careful dissection along surgical planes; careful attention to the choice of regional transection sites; reconstruction using full-thickness anastomoses; use of a minimally invasive procedure with prohemostatic pretreatment and hemorrhage control; prevention of hypothermic damage; reduction in the length of the procedure; and accelerated surgical recovery using fast-track surgical modalities such as perioperative permissive underfeeding and goal-directed volume therapy.

RESULTS: The series of modifications we adopted reduced operation time from 110.02 ± 12.34 min to 78.39 ± 7.26 min (P < 0.01), and the procedural success rate increased from 43.3% (13/30) to 90% (18/20) (P < 0.01), with a long-term survival of 83.3% (15/18) (P < 0.01).

CONCLUSION: Using a number of fast-track and damage control surgical techniques, we have successfully established a stable model of gastric bypass in diabetic rats.