The nutritional energy to clinical outcome relation revisited

Safety of increasing protein delivery with an enteral nutrition formula containing very high protein (VHP) and lower carbohydrate concentrations compared to conventional standard (SF) and high protein (HP) formulas

BACKGROUND & AIMS

Studies demonstrate that caloric restriction in the first seven days in the ICU is safe. The amount of protein that should be delivered, however, is still unclear with clinical trials suggesting mixed results. Despite some capacity to customize the delivery of protein using supplemental modules, protein delivered is best determined by the concentration of protein contained in enteral formula (EF) ordered. This fact provides an opportunity to explore the potential clinical effects of protein delivery and lower carbohydrate intake on clinical outcomes compared with conventional enteral formulas.

METHODS

Retrospective analysis of clinical outcomes according to the amount of protein delivered in critically ill patients admitted to intensive care units at Geisinger Health System.

RESULTS

2000 encounters (1899 patients) in patients on enteral nutrition were divided into three groups receiving EF with either ≤20% protein (standard formula - SF), 21-25% protein (high protein - HP) or > 25% protein (VHP). Protein intake increased up to day 7 (p < 0.0001). Patients on VHP received more protein than other groups (p < 0.0001). Multivariable regression analysis showed no evidence of harm. In fact, we observed increased mortality with SF and HP formulas at 30-days post-discharge when compared to patients on VHP even when the effects of other variables (including age, BMI, sex, primary diagnosis, diabetes, history of dialysis, ICU days kept NPO) were taken into consideration.

CONCLUSIONS

Increasing protein intake while reducing carbohydrate intake appears to be safe. Further research aimed at defining a causative effect of increasing protein delivery while reducing carbohydrate load on outcomes is warranted.

The goldilocks problem: Nutrition and its impact on glycaemic control

BACKGROUND

Glucose intolerance and insulin resistance manifest as hyperglycaemia in intensive care, which is associated with mortality and morbidities. Glycaemic control (GC) may improve outcomes, though safe and effective control has proven elusive. Nutritional glucose intake affects blood glucose (BG) outcomes, but few protocols actively control it. This study aims to examine BG outcomes in the context of nutritional management during GC.

METHODS

Retrospective cohort analysis of 5 glycaemic control cohorts spanning 4 years (n = 273) from Christchurch Hospital Intensive Care Unit (ICU). GC is delivered using a single model-based protocol (STAR), with default 4.4-8.0 mmol/L target range via. modulation of insulin and nutrition. Clinical adaptations/cohorts include variations on upper target (UL-9 with 9.0 mmol/L, reducing workload and nutrition responsiveness), and insulin only (IO) with clinically set nutrition at 3 glucose concentrations (71 g/L vs. 120 and 180 g/L in the TARGET study).

RESULTS

Percent of BG hours in the 4.4-8.0 mmol/L range highest under standard STAR conditions (78%), and was lower at 64% under UL-9, likely due to reduced time-responsiveness of nutrition-insulin changes. By comparison, IO only resulted in 64-69% BG in range across different nutrition types. A subset of patients receiving high glucose nutrition under IO were persistently hyperglycaemic, indicating patient-specific glucose tolerance.

CONCLUSION

STAR GC is most effective when nutrition and insulin are modulated together with timely responsiveness to persistent hyperglycaemia. Results imply modulation of nutrition alongside insulin improves GC, particularly in patients with persistent hyperglycaemia/low glucose tolerance.

ESPEN guideline on clinical nutrition in the intensive care unit

Following the new ESPEN Standard Operating Procedures, the previous guidelines to provide best medical nutritional therapy to critically ill patients have been updated. These guidelines define who are the patients at risk, how to assess nutritional status of an ICU patient, how to define the amount of energy to provide, the route to choose and how to adapt according to various clinical conditions. When to start and how to progress in the administration of adequate provision of nutrients is also described. The best determination of amount and nature of carbohydrates, fat and protein are suggested. Special attention is given to glutamine and omega-3 fatty acids. Particular conditions frequently observed in intensive care such as patients with dysphagia, frail patients, multiple trauma patients, abdominal surgery, sepsis, and obesity are discussed to guide the practitioner toward the best evidence based therapy. Monitoring of this nutritional therapy is discussed in a separate document.

Nutritional support in critical illness and recovery

An adequate nutritional status is crucial for optimum function of cells and organs, and for wound healing. Options for artificial nutrition have greatly expanded in the past few decades, but have concomitantly shown limitations and potential side-effects. Few rigorous randomised controlled trials (RCTs) have investigated enteral or parenteral nutritional support, and evidence-based clinical guidance is largely restricted to the first week of critical illness. In the early stages of critical illness, whether artificial feeding is better than no feeding intervention has been given little attention in existing RCTs. Expected beneficial effects of various forms of early feeding interventions on rates of morbidity or mortality have generally not been supported by results of recent high-quality RCTs. Thus, whether nutritional interventions early in an intensive care unit (ICU) stay improve outcomes remains unclear. Trials assessing feeding interventions that continue after the first week of critical illness and into the post-ICU and post-hospital settings are clearly needed. Although acute morbidity and mortality will remain important safety parameters in such trials, primary outcomes should perhaps, in view of the adjunctive nature of nutritional intervention in critical illness, be focused on physical function and assessed months or even years after patients are discharged from the ICU. This Series paper is based on results of high-quality RCTs and provides new perspectives on nutritional support during critical illness and recovery.

Muscle weakness and nutrition therapy in ICU

PURPOSE OF REVIEW

Muscle wasting is common in severe critical illness. ICU-acquired weakness (ICU-AW) contributes to acute and long-term morbidity and mortality. The question remains whether nutrition therapy in ICU can prevent or attenuate these complications. This review aims at integrating the most recent clinical data in order to answer this important clinical and research question. Clinical evidence was obtained from randomized controlled trials (RCTs). Results from animal experiments and observational studies are referred to when - respectively - providing possible explanatory mechanisms or new hypotheses.

RECENT FINDINGS

Although muscle wasting has been reproducibly quantified early in ICU, its relationship with ICU-AW has not yet been convincingly established. All recent RCTs evaluating increased energy/protein intake during ICU week 1 failed to demonstrate a protective effect against ICU-AW or physical function limitations. In one RCT, early parenteral nutrition increased the incidence of ICU-AW. The latter finding might be explained by suppressed autophagy.

SUMMARY

Current evidence does not support improved physical function with increased energy/protein provision in the first ICU week. Future RCTs aimed at reducing the burden of ICU-AW and improving long-term function should particularly focus on nutrition beyond the acute phase of critical illness and on non-nutritional interventions such as early mobilization.

When and how should sepsis patients be fed?

PURPOSE OF REVIEW

To provide an overview on the recent literature regarding metabolism during sepsis and outcome-related effects of nutrition therapy in septic patients. The question when and how these patients should be fed with respect to macronutrient intake is elaborated.

RECENT FINDINGS

Although the incidence of severe sepsis has steadily increased over the past years, still no strong evidence is available with respect to the role of energy and protein provision in these patients. On the basis of recent large randomized trials in mixed patient populations, the updated sepsis guidelines recommend early but limited nutrition via the enteral route rather than targeted feeding. Lately, the results of a large trial challenged the importance of the route of feeding on the clinical outcome of critically ill patients. Four post-hoc analyses of prospective randomized trials including a large number of severely septic patients yielded conflicting results. One reported significant mortality reduction with near-target calorie and protein intake by exclusive enteral nutrition, whereas the second showed an advantage of enteral compared to combined nutrition, albeit resulting in a lower calorie and protein provision. The other two analyses found no association at all of either lower or higher daily caloric or protein intake, respectively, with clinical outcomes.

SUMMARY

In the absence of strong clinical evidence, pathophysiological findings are discussed and nutritional strategies for septic patients derived. Future studies should explore the individual response to specific exogenous supply of macronutrients and micronutrients in the acute and persistent phase of severe systemic inflammation.

Gastric residual volume in critically ill patients: a dead marker or still alive?

Early enteral nutrition (EN) is consistently recommended as first-line nutrition therapy in critically ill patients since it favorably alters outcome, providing both nutrition and nonnutrition benefits. However, critically ill patients receiving mechanical ventilation are at risk for regurgitation, pulmonary aspiration, and eventually ventilator-associated pneumonia (VAP). EN may increase these risks when gastrointestinal (GI) dysfunction is present. Gastric residual volume (GRV) is considered a surrogate parameter of GI dysfunction during the progression of enteral feeding in the early phase of critical illness and beyond. By monitoring GRV, clinicians may detect patients with delayed gastric emptying earlier and intervene with strategies that minimize or prevent VAP as one of the major risks of EN. The value of periodic GRV measurements with regard to risk reduction of VAP incidence has frequently been questioned in the past years. Increasing the GRV threshold before interrupting gastric feeding results in marginal increases in EN delivery. More recently, a large randomized clinical trial revealed that abandoning GRV monitoring did not negatively affect clinical outcomes (including VAP) in mechanically ventilated patients. The results have revived the discussion on the role of GRV monitoring in critically ill, mechanically ventilated patients receiving early EN. This review summarizes the most recent clinical evidence on the use of GRV monitoring in critically ill patients. Based on the clinical evidence, it discusses the pros and cons and further addresses whether GRV is a dead marker or still alive for the nutrition management of critically ill patients.