Best evidence in critical care medicine. Early versus late parenteral nutrition in the adult ICU: feeding the patient or our conscience?

Effect of Early Versus Delayed Parenteral Nutrition on the Health Outcomes of Critically Ill Adults: A Systematic Review

Objectives

This systematic review aims to evaluate and summarise the findings of all relevant studies which identified the effect of early vs delayed parenteral nutrition (PN), early PN vs early supplemental PN and early PN vs standard care for critically ill adults.

Methods

The literature search was undertaken using PubMed, Embase, Medline, Clinical Key, and Ovid discovery databases. The reference lists of studies published from 2000 till June 2020 were hand searched.

Result

On screening 2088 articles, a total of five RCTs with 6,277 patients were included in this review. Only one clinical trial compared early PN and late PN; the results reported significantly shorter periods in intensive care unit (ICU) stay (p=0.02) and less ICU related infections (p=0.008) in the late PN group compared to the Early PN group. Two trials compared total parenteral nutrition (TPN) and enteral nutrition (EN) +TPN groups. Both found a significantly longer hospital stay duration (p<0.05 and p<0.01) with a higher mortality rate in the TPN group compared to the EN+TPN group. A statistically significant improvement was observed in patients' quality of life receiving early PN compared to standard care (p=0.01). In contrast, no significant difference was found in the supplemental PN vs the standard care group.

Conclusion

The supplemental PN patients had shorter ICU stay and lower mortality rates than TPN. However, these findings should be interpreted carefully as included studies have different initiation timing of nutritional support, and the patients' diagnosis varied.

Early enteral nutrition (within 48 hours) versus delayed enteral nutrition (after 48 hours) with or without supplemental parenteral nutrition in critically ill adults

BACKGROUND

Early enteral nutrition support (within 48 hours of admission or injury) is frequently recommended for the management of patients in intensive care units (ICU). Early enteral nutrition is recommended in many clinical practice guidelines, although there appears to be a lack of evidence for its use and benefit.

OBJECTIVES

To evaluate the efficacy and safety of early enteral nutrition (initiated within 48 hours of initial injury or ICU admission) versus delayed enteral nutrition (initiated later than 48 hours after initial injury or ICU admission), with or without supplemental parenteral nutrition, in critically ill adults.

SEARCH METHODS

We searched CENTRAL (2019, Issue 4), MEDLINE Ovid (1946 to April 2019), Embase Ovid SP (1974 to April 2019), CINAHL EBSCO (1982 to April 2019), and ISI Web of Science (1945 to April 2019). We also searched Turning Research Into Practice (TRIP), trial registers (ClinicalTrials.gov, ISRCTN registry), and scientific conference reports, including the American Society for Parenteral and Enteral Nutrition and the European Society for Clinical Nutrition and Metabolism. We applied no restrictions by language or publication status.

SELECTION CRITERIA

We included all randomized controlled trials (RCTs) that compared early versus delayed enteral nutrition, with or without supplemental parenteral nutrition, in adults who were in the ICU for longer than 72 hours. This included individuals admitted for medical, surgical, and trauma diagnoses, and who required any type of enteral nutrition.

DATA COLLECTION AND ANALYSIS

Two review authors extracted study data and assessed the risk of bias in the included studies. We expressed results as risk ratios (RR) for dichotomous data, and as mean differences (MD) for continuous data, both with 95% confidence intervals (CI). We assessed the certainty of the evidence using GRADE.

MAIN RESULTS

We included seven RCTs with a total of 345 participants. Outcome data were limited, and we judged many trials to have an unclear risk of bias in several domains. Early versus delayed enteral nutrition Six trials (318 participants) assessed early versus delayed enteral nutrition in general, medical, and trauma ICUs in the USA, Australia, Greece, India, and Russia. Primary outcomes Five studies (259 participants) measured mortality. It is uncertain whether early enteral nutrition affects the risk of mortality within 30 days (RR 1.00, 95% CI 0.16 to 6.38; 1 study, 38 participants; very low-quality evidence). Four studies (221 participants) reported mortality without describing the timeframe; we did not pool these results. None of the studies reported a clear difference in mortality between groups. Three studies (156 participants) reported infectious complications. We were unable to pool the results due to unreported data and substantial clinical heterogeneity. The results were inconsistent across studies. One trial measured feed intolerance or gastrointestinal complications; it is uncertain whether early enteral nutrition affects this outcome (RR 0.84, 95% CI 0.35 to 2.01; 59 participants; very low-quality evidence). Secondary outcomes One trial assessed hospital length of stay and reported a longer stay in the early enteral group (median 15 days (interquartile range (IQR) 9.5 to 20) versus 12 days (IQR 7.5 to15); P = 0.05; 59 participants; very low-quality evidence). Three studies (125 participants) reported the duration of mechanical ventilation. We did not pool the results due to clinical and statistical heterogeneity. The results were inconsistent across studies. It is uncertain whether early enteral nutrition affects the risk of pneumonia (RR 0.77, 95% CI 0.55 to 1.06; 4 studies, 192 participants; very low-quality evidence). Early enteral nutrition with supplemental parenteral nutrition versus delayed enteral nutrition with supplemental parenteral nutrition We identified one trial in a burn ICU in the USA (27 participants). Primary outcomes It is uncertain whether early enteral nutrition with supplemental parenteral nutrition affects the risk of mortality (RR 0.74, 95% CI 0.25 to 2.18; very low-quality evidence), or infectious complications (MD 0.00, 95% CI -1.94 to 1.94; very low-quality evidence). There were no data available for feed intolerance or gastrointestinal complications. Secondary outcomes It is uncertain whether early enteral nutrition with supplemental parenteral nutrition reduces the duration of mechanical ventilation (MD 9.00, 95% CI -10.99 to 28.99; very low-quality evidence). There were no data available for hospital length of stay or pneumonia.

AUTHORS' CONCLUSIONS

Due to very low-quality evidence, we are uncertain whether early enteral nutrition, compared with delayed enteral nutrition, affects the risk of mortality within 30 days, feed intolerance or gastrointestinal complications, or pneumonia. Due to very low-quality evidence, we are uncertain if early enteral nutrition with supplemental parenteral nutrition compared with delayed enteral nutrition with supplemental parenteral nutrition reduces mortality, infectious complications, or duration of mechanical ventilation. There is currently insufficient evidence; there is a need for large, multicentred studies with rigorous methodology, which measure important clinical outcomes.

Nutrition Support Protocols: Enhancing Delivery of Enteral Nutrition

In critical care, malnutrition has a significant, negative impact on a patient's ability to respond to medical treatment. Enteral nutrition is known to counteract the metabolic changes associated with critical illness that increase the risk for serious complications and poor clinical outcomes. Inadequate delivery of nutrition support and underfeeding persist in intensive care units despite the availability of guidelines and current research for best practice. Recent studies have shown that nutrition support protocols are effective in promoting nutritional goals in a wide variety of intensive care patients. It is essential to find approaches that enhance early delivery of enteral nutrition that meets requirements and supports improved outcomes. Nurses are in a unique position to take an active role in promoting the best nutritional outcomes for their patients by using and evaluating nutrition support protocols.