Category Archives: Nutrition

Metabolic challenges: Ketogenic diet in General ICU patients

Zudin Puthucheary (London, UK)

Muscle wasting is rapid in critical illness

Muscle protein synthesis

  • Impaired (same rate as fasted controls) from Day 1 of critical illness despite feeding
  • Recovery rate is variable
  • Highly energy-dependent process, uses 40-60% of energy in cell


ATP content in muscle falls on Day 1 of critical illness

  • more marked in pts with pre-existing illness
  • continues over first week despite adequate feeding

Glucose  –> Pyruvate –> Acetyl CoA –> ATP production and further ATP via e-transport chain (total ~38ATP)

In critical illness (hypoxia + inflammation)

  • Pyruvate diverted to lactate (Pasteur effect inhibition of pyruvate dehydrogenase kinase) – very inefficient form of fuel
  • Mitochondrial beta-oxidation of fatty acids blocked (normally excellent source of energy ~125ATP / gram) –> build-up of fat in muscle, cannot be used for energy production
  • Amino acids unlikely to be useful (no human data for this to date)

–>> So energy-dependent protein synthesis greatly limited

Ketone bodies (Acetoacetate, beta-Hydroxybutyrate) can bypass 1) Pasteur effect  (pyruvate diversion to lactate) and 2) block on beta-oxidation of fatty acids

–>> forms basis of Alternative Substrates In the Critically ill Subject (ASICS) trial NCT04101071 – currently recruiting

Metabolic challenges: Ketogenic diet in brain injury

Mauro Oddo (Lausanne, Switzerland)

Alternative substrates: Acetoacetate, beta-Hydroxybutyrate (BHB) = ketone bodies from adipolysis in liver

  • Mono-carboxylate transporter (MCT) directly transfers ketones into mitochondria
  • bypass glycolysis –> Acetyl CoA –> energy production
  • can be utilised by brain, muscle, heart, kidney but not liver

Must distinguish physiological ketone production + nutritional intervention from pathophysiological production (DKA)


Ketones in Brain Injury

  • protect brain from glycolytic flux
  • confer energetic advantage
  • decrease oxidative stress and inflammation

In humans with acute TBI

  • brain ketone levels (extracellular fluid) correlate well with blood ketone levels
  • intense production of ketones in acute phase, up to 1mmol/L (even higher on ketogenic diet)

Ketogenic diets

Medium-chain triglycerides – slow, relatively limited increase in plasma levels over time (~0.5mmol/L BHB)

Ketone esters – rapid increase to keto-therapeutic plasma levels (2-3mmol/L BHB) in healthy volunteers

Brain energy provision by ketones increases proportionately with increasing plasma ketone levels (0.5mM => 5% energy provision; 1.5mM => 20%; 5mM => 60%)

*Upcoming trial, awaiting ethical approval



The nurse is the cornerstone of nutrition delivery (Nestle Health Science sponsored session)

Nurse driven metabolic care

(Mette Berger)

Pts with lower cumulative protein and energy deficits are 3x more likely to go home

ICU is a changeful environment – multiple factors preventing pts from being fed to prescribed goals, but the MAIN problem is often getting EN prescribed / re-started

Nurse-driven protocols (e.g. insulin infusion, catheter infection prevention, resuscitation etc) have a track record of working well!

–> Can Nutrition be nurse-driven, independent of doctors?

  • focus on glycaemic control
  • initiation / resumption of feeding
  • tube placement / control
  • monitoring of delivery

Clear protocols listing roles with describing their responsibilities

Metabolism and nutritional needs vary through the phases of critical illness / during rehabilitation

Nutritional Risk Score (NRS) to identify pts at risk of nutrition-related complications

Glycaemic control

  • demonstrable improvement in tight glucose control when transferred to the care of nurses
  • nurse immediately available to assess and respond to BMs

Initiation of Feeding

  • gastric residues may prevent feeding first 48 hrs post-op
  • can check using ultrasound
  • try pro kinetics during this time

Tube placement

  • tube checking protocols

Monitoring delivery

  • ESPEN guidelines suggest progressively increasing feeding; aggressive early feeding risks hurting sick gut

  • do NOT aim to cover prescribed feeding goals in the first week
  • nurse is well-positioned to detect signs of pt tolerating / not tolerating feed
  • Beware absent stools – Encourage emollients and fibres in feed upon initiation of feeding – this should not cause significant diarrhoea


**Metabolic rationale for starting slow:

Endogenous glucose production is stopped by eating (in healthy people) – this mechanism is lost in critical illness, and therefore there is continuous endogenous glucose production of 200-300g glucose / day = 800kcal even if EN is commenced

–> therefore, starting with a full feed will result in overfeeding


A nursing perspective on nutrition

(Beatrice Jenni-Moser, M-M Jeitziner)

Nutrition has a significant impact on a pt’s ability to respond to medical / nursing treatment

Large variation in nursing practices around nutrition (availability of nutritional guidelines, knowledge and leadership)

Nutrition is often prioritised lower than other care needs

** pt’s relatives are often concerned about having ‘enough to eat’

New paradigm of rehabilitation: Start early, not at the end of medical treatment

–> the same should apply to nutrition – need an MDT approach


Quality project

  • Setting: Interdisciplinary ICU / 37 beds
  • Approx 4000pts / year
  • Length of stay: 2.4days (mean); 8% of pts stay 7days or more

Aim: Overview of nutrition, diarrhoea and constipation

Method: Chart reviews

Sample: (Neurological disease 40%)

2018 – 97 pts, mean age 61.4 (16-90)

2017 – 93 pts, mean age 60.2 (21-94)

— Protocol designed around existing guidelines for patients and also potentially difficult pts

  • EN as the standard approach, early EN within 48 hrs
  • Continuous rather than bolus EN
  • Contraindication to oral, EN –> PN should start within 3-7 days
  • Early and progressive PN is better than starvation
  • After 3 days, caloric delivery can be increased up to 80-100%

Nutritional Assessment: In-depth evaluation of objective and subjective data related to an individual’s food and nutrient intake, lifestyle, medical history

Combine with Frailty scale in every pt for a baseline frailty score (not just in the older pts / long stay)

Take home message: ICU nurses are in a unique situation to take an active role in promoting the best nutritional outcomes to the pts

  • interprofessional nutrition education
  • nutritional screening and assessment
  • using standardised guidelines / protocols
  • evaluating nutrition support