Designing nutrition-based interventional trials for the future: addressing the known knowns

Novel Strategies to Promote Intensive Care Unit Recovery via Personalized Exercise, Nutrition, and Anabolic Interventions

Survivors of critical illness experience significant morbidity, reduced physiologic reserve, and long-term complications that negatively impact quality of life. Although rehabilitative treatments are beneficial during early recovery, there is limited evidence regarding effective multimodal rehabilitation, nutrition, and anabolic nutrient/agent strategies for improving long-term outcomes. This review discusses novel personalized rehabilitation, nutrition, and anabolic nutrient/agent (ie, creatine, β-hydroxy-β-methylbutyrate, testosterone) approaches that allow for precise exercise and nutrition prescription and have potential to improve patient care, address continued medical needs, and optimize long-term recovery. Continued research is needed to further evaluate effectiveness and implementation of these strategies throughout the continuum of care.

Why One-Size-Fits-All Doesn't Work in Intensive Care Unit Nutrition?

Nutrition therapy is a complex intervention with several underlying considerations that may influence effectiveness. Considerations include the mechanism of action of the intervention and the patient phenotype, including sex, ethnicity, body composition, and the patients' nutritional and inflammatory status. Energy and protein targets are elements of nutrition therapy that may be particularly influenced by individual patient factors. Biomarkers may provide a useful tool to monitor and individualize nutrition therapy in the future. The considerations mentioned, with many yet to be studied, highlight the rationale for more individualized interventions moving away from a 'one-size-fits-all' approach.

Which Outcomes Should We be Using in Critical Care Nutrition Trials?

Selecting appropriate outcome measures is a critical component of clinical trial design. Core outcome sets, which utilize stakeholder input to define the most important outcomes for a particular research question, are valuable in improving the consistency of research, such that conclusive recommendations can be made. Alongside these core outcomes, exploratory outcomes are keys to providing novel insights into disease pathophysiology and treatment response. Surrogate outcomes developed through exploratory methods may enable intervention at an earlier stage, with the potential for prevention rather than management of the sequalae of critical illness.

Dietetic-led interventions in critically ill adults that influence outcome: A scoping review

BACKGROUND

Critically ill patients face malnutrition risks, making nutrition management challenging. Dietitians play a crucial role in the intensive care unit (ICU) by applying their expertise to address these challenges. This review examines dietitian-led interventions and their impact on patient outcomes.

METHODS

A scoping review of MEDLINE, Embase, CINAHL, EBSCO, Web of Science, and ProQuest databases from January 1995 to July 2023 was conducted. Studies involving dietitian-led interventions in adult critical care were included. Data extraction followed Joanna Briggs Institute methodology, focusing on study design, population, and interventions.

RESULTS

Of 751 studies, 39 met the inclusion criteria. Most studies were observational, with only three interventional trials. Dietitian-led interventions included (1) guideline development and implementation, (2) individualized nutrition treatment, and (3) enteral nutrition tube insertion. Outcomes were classified into (1) patient clinical outcomes (ICU stay duration, mechanical ventilation, infections, cost savings, readmissions, mortality, adverse effects, and glycemic control) and (2) nutrition-related outcomes (nutrition initiation, energy and protein delivery, gastrointestinal tolerance, parenteral nutrition use, and appropriate dietetic referral).

CONCLUSION

Dietitian-led interventions improved nutrition outcomes and may have contributed to better clinical outcomes. Future research should prioritize reporting core outcomes, including nutrition status and physical function, to further quantify the effectiveness of dietitians in ICU care and enhance their recognition within the multiprofessional team.

Reporting of nutritional screening, status, and intake in trials of nutritional and physical rehabilitation following critical illness: a systematic review

BACKGROUND

Surviving critical illness leads to prolonged physical and functional recovery with both nutritional and physical rehabilitation interventions for prevention and treatment being investigated. Nutritional status and adequacy may influence outcome, but no consensus on which nutritional-related variables should be measured and reported in clinical trials exists.

OBJECTIVES

This study aimed to undertake a systematic review investigating the reporting of nutritional screening, nutritional status, and nutritional intake/delivery in randomized controlled trials (RCTs) evaluating nutritional and/or physical rehabilitation on physical and functional recovery during and following critical illness.

METHODS

Five electronic databases (MEDLINE, Web of Science, EMBASE, CINAHL, and Cochrane) were searched (last update 9 August, 2023). Search terms included both free text and standardized indexed terms. Studies included were RCTs assessing nutritional and/or physical interventions either during or following intensive care unit (ICU) admission in adults (18 y or older) with critical illness, and who required invasive mechanical ventilation for any duration during ICU admission. Study quality was assessed using the Cochrane Collaboration Risk of Bias tool for RCTs and descriptive data synthesis was performed and presented as counts (%). n t RESULTS: In total, 123 RCTs (30 nutritional, 87 physical function, and 6 combined) were included. Further, ≥1 nutritional variable was measured and/or reported in 99 (80%) of the studies including BMI (n = 69), body weight (n = 57), nutritional status (n = 11), nutritional risk (n = 10), energy delivery (n = 41), protein delivery (n = 35), handgrip strength (n = 40), and other nutritional-related muscle variables (n = 41). Only 3 studies were considered to have low risk of bias in all categories.

CONCLUSIONS

Few RCTs of physical rehabilitation measure and report nutritional or related variables. Future studies should measure and report specific nutritional factors that could impact physical and functional recovery to support interpretation where studies do not show benefit. This protocol was preregistered at PROSPERO as CRD42022315122.

Responsiveness of Critically Ill Adults With Multimorbidity to Rehabilitation Interventions: A Patient-Level Meta-Analysis Using Individual Pooled Data From Four Randomized Trials

OBJECTIVE

To explore if patient characteristics (pre-existing comorbidity, age, sex, and illness severity) modify the effect of physical rehabilitation (intervention vs control) for the coprimary outcomes health-related quality of life (HRQoL) and objective physical performance using pooled individual patient data from randomized controlled trials (RCTs).

DATA SOURCES

Data of individual patients from four critical care physical rehabilitation RCTs.

STUDY SELECTION

Eligible trials were identified from a published systematic review.

DATA EXTRACTION

Data sharing agreements were executed permitting transfer of anonymized data of individual patients from four trials to form one large, combined dataset. The pooled trial data were analyzed with linear mixed models fitted with fixed effects for treatment group, time, and trial.

DATA SYNTHESIS

Four trials contributed data resulting in a combined total of 810 patients (intervention n = 403, control n = 407). After receiving trial rehabilitation interventions, patients with two or more comorbidities had HRQoL scores that were significantly higher and exceeded the minimal important difference at 3 and 6 months compared with the similarly comorbid control group (based on the Physical Component Summary score (Wald test p = 0.041). Patients with one or no comorbidities who received intervention had no HRQoL outcome differences at 3 and 6 months when compared with similarly comorbid control patients. No patient characteristic modified the physical performance outcome in patients who received physical rehabilitation.

CONCLUSIONS

The identification of a target group with two or more comorbidities who derived benefits from the trial interventions is an important finding and provides direction for future investigations into the effect of rehabilitation. The multimorbid post-ICU population may be a select population for future prospective investigations into the effect of physical rehabilitation.

Personalized nutrition therapy in critical care: 10 expert recommendations

Personalization of ICU nutrition is essential to future of critical care. Recommendations from American/European guidelines and practice suggestions incorporating recent literature are presented. Low-dose enteral nutrition (EN) or parenteral nutrition (PN) can be started within 48 h of admission. While EN is preferred route of delivery, new data highlight PN can be given safely without increased risk; thus, when early EN is not feasible, provision of isocaloric PN is effective and results in similar outcomes. Indirect calorimetry (IC) measurement of energy expenditure (EE) is recommended by both European/American guidelines after stabilization post-ICU admission. Below-measured EE (~ 70%) targets should be used during early phase and increased to match EE later in stay. Low-dose protein delivery can be used early (~ D1-2) (< 0.8 g/kg/d) and progressed to ≥ 1.2 g/kg/d as patients stabilize, with consideration of avoiding higher protein in unstable patients and in acute kidney injury not on CRRT. Intermittent-feeding schedules hold promise for further research. Clinicians must be aware of delivered energy/protein and what percentage of targets delivered nutrition represents. Computerized nutrition monitoring systems/platforms have become widely available. In patients at risk of micronutrient/vitamin losses (i.e., CRRT), evaluation of micronutrient levels should be considered post-ICU days 5-7 with repletion of deficiencies where indicated. In future, we hope use of muscle monitors such as ultrasound, CT scan, and/or BIA will be utilized to assess nutrition risk and monitor response to nutrition. Use of specialized anabolic nutrients such as HMB, creatine, and leucine to improve strength/muscle mass is promising in other populations and deserves future study. In post-ICU setting, continued use of IC measurement and other muscle measures should be considered to guide nutrition. Research on using rehabilitation interventions such as cardiopulmonary exercise testing (CPET) to guide post-ICU exercise/rehabilitation prescription and using anabolic agents such as testosterone/oxandrolone to promote post-ICU recovery is needed.

Novel nutritional strategies to prevent muscle wasting

PURPOSE OF REVIEW

Muscle wasting in critical illness has proven to be refractory to physical rehabilitation, and to conventional nutritional strategies. This presents one of the central challenges to critical care medicine in the 21st century. Novel strategies are needed that facilitate nutritional interventions, identify patients that will benefit and have measurable, relevant benefits.

RECENT FINDINGS

Drug repurposing was demonstrated to be a powerful technique in the coronavirus disease 2019 pandemic, and may have similar applications to address the metabolic derangements of critical illness. Newer biological signatures may aid the application of these techniques and the association between changes in urea:creatinine ratio and the development of skeletal muscle wasting is increasing. A core outcome set for nutrition interventions in critical illness, supported by multiple international societies, was published earlier this year should be adopted by future nutrition trials aiming to attenuate muscle wasting.

SUMMARY

The evidence base for the lack of efficacy for conventional nutritional strategies in preventing muscle wasting in critically ill patients continues to grow. Novel strategies such as metabolic modulators, patient level biological signatures of nutritional response and standardized outcome for measurements of efficacy will be central to future research and clinical care of the critically ill patient.

Are periods of feeding and fasting protective during critical illness?

PURPOSE OF REVIEW

To review the mechanisms how intermittent feeding regimens could be beneficial in critically ill patients.

RECENT FINDINGS

Large randomized controlled trials (RCTs) have failed to demonstrate consistent benefit of early, enhanced nutritional support to critically ill patients, and some trials even found potential harm. Although speculative, the absence of a clear benefit could be explained by the continuous mode of feeding in these trials, since intermittent feeding regimens had health-promoting effects in healthy animals and humans through mechanisms that also appear relevant in critical illness. Potential protective mechanisms include avoidance of the muscle-full effect and improved protein synthesis, improved insulin sensitivity, better preservation of circadian rhythm, and fasting-induced stimulation of autophagy and ketogenesis. RCTs comparing continuous versus intermittent feeding regimens in critically ill patients have shown mixed results, albeit with different design and inclusion of relatively few patients. In all studies, the fasting interval was relatively short (4-6 h maximum), which may be insufficient to develop a full fasting response and associated benefits.

SUMMARY

These findings open perspectives for the design and clinical validation of intermittent feeding regimens for critically ill patients. The optimal mode and duration of the fasting interval, if any, remain unclear.

Implications for post critical illness trial design: sub-phenotyping trajectories of functional recovery among sepsis survivors

BACKGROUND

Patients who survive critical illness suffer from a significant physical disability. The impact of rehabilitation strategies on health-related quality of life is inconsistent, with population heterogeneity cited as one potential confounder. This secondary analysis aimed to (1) examine trajectories of functional recovery in critically ill patients to delineate sub-phenotypes and (2) to assess differences between these cohorts in both clinical characteristics and clinimetric properties of physical function assessment tools.

METHODS

Two hundred ninety-one adult sepsis survivors were followed-up for 24 months by telephone interviews. Physical function was assessed using the Physical Component Score (PCS) of the Short Form-36 Questionnaire (SF-36) and Activities of Daily Living and the Extra Short Musculoskeletal Function Assessment (XSFMA-F/B). Longitudinal trajectories were clustered by factor analysis. Logistical regression analyses were applied to patient characteristics potentially determining cluster allocation. Responsiveness, floor and ceiling effects and concurrent validity were assessed within clusters.

RESULTS

One hundred fifty-nine patients completed 24 months of follow-up, presenting overall low PCS scores. Two distinct sub-cohorts were identified, exhibiting complete recovery or persistent impairment. A third sub-cohort could not be classified into either trajectory. Age, education level and number of co-morbidities were independent determinants of poor recovery (AUROC 0.743 ((95%CI 0.659-0.826), p < 0.001). Those with complete recovery trajectories demonstrated high levels of ceiling effects in physical function (PF) (15%), role physical (RP) (45%) and body pain (BP) (57%) domains of the SF-36. Those with persistent impairment demonstrated high levels of floor effects in the same domains: PF (21%), RP (71%) and BP (12%). The PF domain demonstrated high responsiveness between ICU discharge and at 6 months and was predictive of a persistent impairment trajectory (AUROC 0.859 (95%CI 0.804-0.914), p < 0.001).

CONCLUSIONS

Within sepsis survivors, two distinct recovery trajectories of physical recovery were demonstrated. Older patients with more co-morbidities and lower educational achievements were more likely to have a persistent physical impairment trajectory. In regard to trajectory prediction, the PF score of the SF-36 was more responsive than the PCS and could be considered for primary outcomes. Future trials should consider adaptive trial designs that can deal with non-responders or sub-cohort specific outcome measures more effectively.

Effect of Intermittent or Continuous Feed on Muscle Wasting in Critical Illness: A Phase 2 Clinical Trial

BACKGROUND

Acute skeletal muscle wasting in critical illness is associated with excess morbidity and mortality. Continuous feeding may suppress muscle protein synthesis as a result of the muscle-full effect, unlike intermittent feeding, which may ameliorate it.

RESEARCH QUESTION

Does intermittent enteral feed decrease muscle wasting compared with continuous feed in critically ill patients?

STUDY DESIGN AND METHODS

In a phase 2 interventional single-blinded randomized controlled trial, 121 mechanically ventilated adult patients with multiorgan failure were recruited following prospective informed consultee assent. They were randomized to the intervention group (intermittent enteral feeding from six 4-hourly feeds per 24 h, n = 62) or control group (standard continuous enteral feeding, n = 59). The primary outcome was 10-day loss of rectus femoris muscle cross-sectional area determined by ultrasound. Secondary outcomes included nutritional target achievements, plasma amino acid concentrations, glycemic control, and physical function milestones.

RESULTS

Muscle loss was similar between arms (-1.1% [95% CI, -6.1% to -4.0%]; P = .676). More intermittently fed patients received 80% or more of target protein (OR, 1.52 [1.16-1.99]; P < .001) and energy (OR, 1.59 [1.21-2.08]; P = .001). Plasma branched-chain amino acid concentrations before and after feeds were similar between arms on trial day 1 (71 μM [44-98 μM]; P = .547) and trial day 10 (239 μM [33-444 μM]; P = .178). During the 10-day intervention period the coefficient of variation for glucose concentrations was higher with intermittent feed (17.84 [18.6-20.4]) vs continuous feed (12.98 [14.0-15.7]; P < .001). However, days with reported hypoglycemia and insulin usage were similar in both groups. Safety profiles, gastric intolerance, physical function milestones, and discharge destinations did not differ between groups.

INTERPRETATION

Intermittent feeding in early critical illness is not shown to preserve muscle mass in this trial despite resulting in a greater achievement of nutritional targets than continuous feeding. However, it is feasible and safe.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT02358512; URL: www.clinicaltrials.gov.