Parenteral nutrition in the ICU setting: need for a shift in utilization

Parenteral Nutrition: Current Use, Complications, and Nutrition Delivery in Critically Ill Patients

BACKGROUND

Parenteral nutrition (PN) is needed to avoid the development of malnutrition when enteral nutrition (EN) is not possible. Our main aim was to assess the current use, complications, and nutrition delivery associated with PN administration in adult critically ill patients, especially when used early and as the initial route. We also assessed the differences between patients who received only PN and those in whom EN was initiated after PN (PN-EN).

METHODS

A multicenter (n = 37) prospective observational study was performed. Patient clinical characteristics, outcomes, and nutrition-related variables were recorded. Statistical differences between subgroups were analyzed accordingly.

RESULTS

From the entire population (n = 629), 186 (29.6%) patients received PN as initial nutrition therapy. Of these, 74 patients (11.7%) also received EN during their ICU stay (i.e., PN-EN subgroup). PN was administered early (<48 h) in the majority of patients (75.3%; n = 140) and the mean caloric (19.94 ± 6.72 Kcal/kg/day) and protein (1.01 ± 0.41 g/kg/day) delivery was similar to other contemporary studies. PN showed similar nutritional delivery when compared with the enteral route. No significant complications were associated with the use of PN. Thirty-two patients (43.3%) presented with EN-related complications in the PN-EN subgroup but received a higher mean protein delivery (0.95 ± 0.43 vs 1.17 ± 0.36 g/kg/day; p = 0.03) compared with PN alone. Once adjusted for confounding factors, patients who received PN alone had a lower mean protein intake (hazard ratio (HR): 0.29; 95% confidence interval (CI): 0.18-0.47; p = 0.001), shorter ICU stay (HR: 0.96; 95% CI: 0.91-0.99; p = 0.008), and fewer days on mechanical ventilation (HR: 0.85; 95% CI: 0.81-0.89; p = 0.001) compared with the PN-EN subgroup.

CONCLUSION

The parenteral route may be safe, even when administered early, and may provide adequate nutrition delivery. Additional EN, when possible, may optimize protein requirements, especially in more severe patients who received initial PN and are expected to have longer ICU stays. NCT Registry: 03634943.

Comparison of Biochemical and Pathological Parameters and Parenteral Nutrition of ICU Patients Under Supervision of Dietitians and Surgeons

Background: Nutrient imbalance can frequently occur in patients with indications for parenteral nutrition (PN) after gastrointestinal surgery. This study aimed to compare the recommendations of a surgeon to those of a dietitian in the field of parenteral nutrition.

Methods: This study was performed on 256 patients undergoing gastrointestinal surgery who received PN, which included 120 patients who received PN based on recommendations of the surgeons and 136 patients who were referred to receive PN under the supervision of a dietitian in Razi Hospital in Rasht, Iran. Data on PN and clinical outcomes of the patients were collected.

Results: Patients under the supervision of dietitians received higher vitamin B complex and lipids and lower vitamin A and vitamin E than the surgeon-supervised patients (all P < 0.001). In the group receiving PN under the supervision of a surgeon, the level of blood glucose (207 vs. 182, P < 0.01), sodium (138 vs. 136, P = 0.01), potassium (3.97 vs. 3.53, P < 0.01), and white blood cell count (9.83 vs. 9.28, P < 0.01) increased significantly at the end of the PN compared to baseline. In the group receiving PN under the supervision of a dietician, the level of serum Cr (1.23 vs. 1.32, P = 0.04), Mg (2.07 vs. 1.84, P < 0.01), and pH (7.45 vs. 7.5, P = 0.03) significantly improved after receiving parenteral nutrition compared to baseline.

Conclusion: The amounts of nutrients recommended for PN by the surgeon and dietitian were different. Implementation of dietitian recommendations in critically ill patients under PN can improve patients' clinical parameters.

Supplemental Parenteral Nutrition: Review of the Literature and Current Nutrition Guidelines

Parenteral nutrition has significantly and positively affected the clinical care of patients for >50 years. The 2016 Society of Critical Care Medicine/American Society for Parenteral and Enteral Nutrition guidelines for the provision of nutrition support to adult patients emphasize the role of this therapy in attenuating the stress response and impacting the immune response, among other benefits. Malnutrition in hospitalized patients remains a major problem; it is underdiagnosed and often undertreated. Malnourished patients are more likely to suffer from infections, pneumonia, and pressure ulcers, among other serious concerns. Enteral nutrition is considered first-line therapy in many of these patients; however, data suggest that many patients receive far less than prescribed amounts for a variety of reasons. Supplemental parenteral nutrition (SPN), used to augment nutrition support of appropriate adult patients and better meet nutrition goals, is not often used in the United States. The purposes of this review are to highlight selected studies in the literature that support and question the use and value of SPN in adult patients; propose consideration of 2 definitions for SPN, "early" and "traditional"; and encourage clinicians to consider SPN for appropriate patients.

Parenteral or enteral nutrition: do you have the choice?

PURPOSE OF REVIEW

The review focuses on the use of parenteral nutrition and enteral nutrition in critically ill patients to optimize the nutrition care throughout the ICU stay. The key message is: you have the choice!

RECENT FINDINGS

Enteral nutrition has been recommended for critically ill patients, whereas parenteral nutrition has been considered harmful and to be avoided. However, recent studies have challenged this theory. They demonstrated that enteral nutrition is frequently associated with energy and protein undernutrition, whereas parenteral nutrition becomes deleterious only if overfeeding is induced. Measuring energy expenditure by indirect calorimetry, in most cases, enables accurate determination of the energy needs to optimize the prescription of nutrition. Protein targets should also be considered for adequate feeding. Parenteral nutrition can be used as a supplement or as an alternative to enteral nutrition in case of gastrointestinal intolerance, to enable adequate energy, and protein provision.

SUMMARY

Parenteral nutrition is a powerful tool to optimize nutrition care of critically ill patients to improve clinical outcome, if prescribed according to the individual needs of the patients. After 3-4 days of attempt to feed enterally, enteral nutrition or parenteral nutrition can be used alternatively or combined, as long as the target is reached with special attention to avoid hypercaloric feeding.

High-Protein Hypocaloric Nutrition for Non-Obese Critically Ill Patients

High-protein hypocaloric nutrition, tailored to each patient's muscle mass, protein-catabolic severity, and exogenous energy tolerance, is the most plausible nutrition therapy in protein-catabolic critical illness. Sufficient protein provision could mitigate the rapid muscle atrophy characteristic of this disease while providing urgently needed amino acids to the central protein compartment and sites of tissue injury. The protein dose may range from 1.5 to 2.5 g protein (1.8-3.0 g free amino acids)/kg dry body weight per day. Nutrition should be low in energy (≈70% of energy expenditure or ≈15 kcal/kg dry body weight per day) because efforts to match energy provision to energy expenditure are physiologically irrational, risk toxic energy overfeeding, and have repeatedly failed in large clinical trials to demonstrate clinical benefit. The American Society for Parenteral and Enteral Nutrition currently suggests high-protein hypocaloric nutrition for obese critically ill patients. Short-term high-protein hypocaloric nutrition is physiologically and clinically sensible for most protein-catabolic critically ill patients, whether obese or not.

Timing of the initiation of parenteral nutrition in critically ill children

PURPOSE OF REVIEW

To review the current literature evaluating clinical outcomes of early and delayed parenteral nutrition initiation among critically ill children.

RECENT FINDINGS

Nutritional management remains an important aspect of care among the critically ill, with enteral nutrition generally preferred. However, inability to advance enteral feeds to caloric goals and contraindications to enteral nutrition often leads to reliance on parenteral nutrition. The timing of parenteral nutrition initiation is varied among critically ill children, and derives from an assessment of nutritional status, energy requirements, and physiologic differences between adults and children, including higher nutrient needs and lower body reserves. A recent randomized control study among critically ill children suggests improved clinical outcomes with avoiding initiation of parenteral nutrition on day 1 of admission to the pediatric ICU.

SUMMARY

Although there is no consensus on the optimal timing of parenteral nutrition initiation among critically ill children, recent literature does not support the immediate initiation of parenteral nutrition on pediatric ICU admission. A common theme in the reviewed literature highlights the importance of accurate assessment of nutritional status and energy expenditure in deciding when to initiate parenteral nutrition. As with all medical interventions, the initiation of parenteral nutrition should be considered in light of the known benefits of judiciously provided nutritional support with the known risks of artificial, parenteral feeding.

Can calculation of energy expenditure based on CO2 measurements replace indirect calorimetry?

BACKGROUND

Methods to calculate energy expenditure (EE) based on CO₂ measurements (EEVCO₂) have been proposed as a surrogate to indirect calorimetry. This study aimed at evaluating whether EEVCO₂ could be considered as an alternative to EE measured by indirect calorimetry.

METHODS

Indirect calorimetry measurements conducted for clinical purposes on 278 mechanically ventilated ICU patients were retrospectively analyzed. EEVCO₂ was calculated by a converted Weir's equation using CO₂ consumption (VCO₂) measured by indirect calorimetry and assumed respiratory quotients (RQ): 0.85 (EEVCO₂_0.85) and food quotient (FQ; EEVCO₂_FQ). Mean calculated EEVCO₂ and measured EE were compared by paired t test. Accuracy of EEVCO₂ was evaluated according to the clinically relevant standard of 5% accuracy rate to the measured EE, and the more general standard of 10% accuracy rate. The effects of the timing of measurement (before or after the 7th ICU day) and energy provision rates (<90 or ≥90% of EE) on 5% accuracy rates were also analyzed (chi-square tests).

RESULTS

Mean biases for EEVCO₂_0.85 and EEVCO₂_FQ were -21 and -48 kcal/d (p = 0.04 and 0.00, respectively), and 10% accuracy rates were 77.7 and 77.3%, respectively. However, 5% accuracy rates were 46.0 and 46.4%, respectively. Accuracy rates were not affected by the timing of the measurement, or the energy provision rates at the time of measurements.

CONCLUSIONS

Calculated EE based on CO₂ measurement was not sufficiently accurate to consider the results as an alternative to measured EE by indirect calorimetry. Therefore, EE measured by indirect calorimetry remains as the gold standard to guide nutrition therapy.

Gastrointestinal dysmotility in the critically ill: a role for nutrition

PURPOSE OF REVIEW

The role of enteral nutrition on gastrointestinal dysmotility in the critically ill remains controversial.

RECENT FINDINGS

The mechanisms of gastrointestinal dysmotility during critical illness remain poorly investigated. Low amounts of enteral feeding stimulate motility and have trophic effects. Therefore, enteral feeding is feasible even during gastrointestinal dysmotility as seen in the hemodynamically compromised patient. Rapid 'ramp-up' of administration rate of tube feeding bears the risk of overload and even detrimental ischemic bowel necrosis. The recent American Society for Parenteral and Enteral Nutrition guidelines do not recommend the measurement of gastric residual volume. The use of concentrated enteral solutions with 1.5 kcal/ml may result in greater calorie delivery. Biomarkers like plasma citrulline and plasma or urine intestinal fatty-acid-binding protein reflect the functional integrity of the bowel and may potentially support monitoring.

SUMMARY

To improve enteral nutrition protocols, the definitions of gastrointestinal dysfunction, gastric dysmotility, and feeding intolerance should be clearly defined in the future. In the concept of integrity of the gut, enteral nutrition should not be stopped completely during gastrointestinal dysfunction but restricted to a 'minimal' trophic feeding rate. In malnourished and high-risk patients intolerant to enteral feeding supplemental parenteral nutrition should be started on day 4 or earlier.