Description
Optimal nutrition is a cornerstone of critical care management, directly influencing patient recovery, immune response, and outcomes. Evidence-based practices emphasize early initiation of enteral nutrition within 24–48 hours of ICU admission to maintain gut integrity and reduce infection risk. Individualized nutritional assessment, guided by indirect calorimetry and protein targets, ensures adequate energy and macronutrient delivery. Parenteral nutrition is reserved for cases where enteral feeding is contraindicated or insufficient. Micronutrient supplementation, glycemic control, and monitoring of refeeding syndrome are essential. Multidisciplinary collaboration among intensivists, dietitians, and nurses enhances nutritional therapy and improves overall ICU survival rates.
Summary Listen
- The dietitian's role in critical care is to provide tailored nutrition support, optimize nutritional delivery, manage feeding tolerance, collaborate with the multi-disciplinary team (MDT), and participate in audit research and education to advance clinical practice. Nutrition is a vital part of the recovery for critically ill patients.
- Critically ill patients require comprehensive monitoring and support due to life-threatening conditions. Characteristics include unstable vitals, complex medical needs, and continuous observation to prevent deterioration. Classifications range from normal ward-based care (Level 0) to advanced respiratory and organ support in intensive care (Level 3).
- Guiding principles include prioritizing patients, respecting individual needs and preferences, maintaining clear communication with families, providing compassion, and involving relatives/caregivers in decision-making. Encouraging feedback is essential to improve patient and family experiences. Rehabilitation is crucial post-ICU to help patients regain strength and weight with the help of an MDT.
- Malnutrition increases complication and mortality risks in critically ill patients, leading to muscle loss and a higher risk of infection. Early and appropriate nutrition improves muscle strength, reduces hospital stay, and shortens ICU stay.
- Physiological challenges include hypermetabolism, inflammation, increased protein breakdown, and immune dysfunction. Inflammation can disrupt the gut barrier, increasing infection risk. Impaired oxygen delivery can cause cardiovascular and respiratory compromise. Goals of nutrition support include promoting muscle mass, enhancing the immune system, supporting gut health, and cultivating recovery through adequate energy intake.
- Screening and assessment tools, such as MUST, NUTRIC score, GLIM criteria, NRS 2002, mid-upper arm circumference (MUAC), and hand grip strength, help identify malnutrition risk. MUST considers BMI and weight loss, while the NUTRIC score factors in age, APACHE score, organ dysfunction, comorbidities, and inflammatory markers.
- Early nutrition is crucial; oral intake is preferred if possible. Enteral nutrition (EN) should start within 24-48 hours of critical care admission if oral intake is insufficient. Parenteral nutrition (PN) is considered if EN is contraindicated or insufficient, but carries a higher infection risk and is costly.
- Enteral nutrition is indicated when the gut is functional and accessible. Nasogastric (NG) and nasojejunal (NJ) tubes are generally preferred over PEG, PEGJ, or surgical jejunostomies due to simpler care and monitoring. EN is contraindicated in uncontrolled shock, life-threatening conditions like acidosis and hypoxia, active GI bleeding, bowel ischemia, and abdominal compartment syndrome.
- Parenteral nutrition, delivered intravenously, is used when EN is not feasible or insufficient. ESPEN guidelines recommend 25-30 kcal/kg/day and 1.3-2 grams of protein/kg/day. Fish oil emulsions may improve outcomes. Gradual feeding initiation is preferred, aiming for target rates by day eight. Daily monitoring of bloods and feed tolerance is necessary.
- Monitoring involves checking gastric residual volume (GRV), bowel function, and managing diarrhea with hydration. Reducing aspiration risk and monitoring for refeeding syndrome via electrolyte checks are important. High glucose levels require monitoring.
- Vasopressor use affects feeding decisions. Low-dose vasopressors may allow for cautious feeding, while high doses (e.g., norepinephrine >0.3 mcg/kg/min) usually contraindicate enteral feeding due to bowel ischemia risk. Signs of ischemia necessitate stopping EN and considering PN.
- Refeeding syndrome occurs when introducing nutrition after prolonged starvation. Monitor electrolytes closely and start nutrition slowly to prevent electrolyte shifts. High-risk patients (BMI <16, significant weight loss) require vigilant monitoring and slow feeding.
- Critical care feeding protocols typically involve NGT placement if safe, starting EN within 48 hours, and choosing fiber or low-fiber feeds based on individual needs. Monitor gastric aspirate; if >300 ml, consider prokinetics like erythromycin or metoclopramide. Delays in feeding can occur due to various medical and logistical reasons.
- Causes of high GRVs include mechanical ventilation, sedation, vasopressors, and sepsis. Prokinetics are used to improve gut motility. Propofol, a common sedative, provides calories that must be considered to avoid overfeeding. Intravenous glucose administration also contributes to caloric intake.
- Critical patients often experience dehydration and high sodium levels, necessitating sodium monitoring and potentially sodium-free feeds. Patients on continuous renal replacement therapy (CRRT) require higher protein intake (1.5-1.7 g/kg/day). Upon extubation, ensure oral intake is established before removing the NGT. Emerging research includes personalized feeding algorithms and the role of immunonutrition with omega-3 fatty acids.
- The case study of a 68-year-old patient with bowel obstruction highlights the complexities of nutrition support in critical care. Initial plans for post-operative EN were thwarted by high GRVs, necessitating TPN. Careful monitoring of electrolyte levels and caloric intake from propofol were crucial. Gradual reintroduction of EN and oral intake led to successful weaning from TPN and transition to a regular diet with oral nutrition supplements.
- Key takeaways include the importance of early individualized nutrition, a multidisciplinary approach, and treating nutrition as a medicine rather than just a supplement.
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About the Speakers
Arlynn Aby George
Senior Dietitian at Medway Maritime Hospital, NHS Trust Foundation, England, United Kingdom
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