ch 16-17 Flashcards
Low Muscularity is Highly Prevalent at ICU Admission
Elderly (79 years) trauma ICU – 71% low muscularity • Of these: 38% overweight, 9% obese Adult (57 years) MSICU – 63% low muscularity Associated with: – ↑ Mortality – ↓ Ventilator-free days – ↑ ICU- and hospital-LOS
Remember: decreased muscle mass is a hallmark indicator of
malnutrition
• Malnutrition is a significant concern in the critically ill
– Many are already malnourished at the time of ICU admission
– Several factors drive lean tissue loss, fat loss and decreased functional
capacity over the course of ICU admission
• Stress / inflammatory response (highly catabolic)
• Inadequate delivery of nutrition throughout the duration of ICU stay
– Pt’s on average receive ~60-65% of prescribed protein and calories (Nicolo et al JPEN 2015)
• Immobilization; ICU-acquired weakness
l
ICU Scores: APACHE II
Acute Physiology and Chronic Health Evaluation II Score
– Also use
– Originally developed to estimate ICU mortality
– Commonly reported in research
– Based on variables in first 24h of ICU admission
• Age, temp, MAP, pH, HR, RR, Na, K, Creat, Hct, WBC, GCS, in ARF, PaO2, hx of
organ insufficiency or immunocompromise
• Worst value in first 24h take
– Range: 0-77, higher = greater severity of illness
• Rarely see 50’s
ICU Scores: SOFA
Sequential Organ Failure Assessment Score
– Also developed to predict ICU outcomes
– Determines extent of organ function / rate of failure
– Also commonly reported in research
– Can be measured/tracked throughout ICU stay
– Based on 6 organ dysfunction indicators:
• PaO2 / FiO2 (Respiratory); GCS (Neuro); MAP and rqmt for vasopressors
(cardiac); Bilirubin (liver); Platelets (coagulation/liver); Creat (kidney)
– Score range: 0-24 (higher = worse)
Head-to-Toe Assessment of a Critically Ill Patient (Systems Review)
Neurological System (CNS) RESP CVS GI Genitourinary System (UG or GU)- urine, diuretics Infectious Diseases (ID) Physical Assessment
NUTRIC Score
The NUTrition Risk In Critically Ill Score
• First nutrition risk assessment tool developed and validated for
ICU patients
• Used to measure the risk of critically ill patients whose
negative outcomes could be modified through aggressive
nutrition therapy
• Based on 6 variables:
– Age, APACHE II, SOFA , Number of comorbidities, Days from hospital
to ICU admission, IL-6 (marker of inflammation)
Modified NUTRIC Score
Same as NUTRIC but excludes the measurement of IL-6 due to
the fact that it is not commonly measured in patients and
difficult to obtain
Traditional / Common Methods Used to Assess
Nutrition Assessment in Non-ICU Patients
Serum protein markers • Anthropometrics – Weight – MAC/MAMC, TSF etc. • SGA • Hand-grip strength
Nutrition Assessment Challenges in ICU Pt’s:
Traditional Serum Protein Markers
Albumin, prealbumin, transferrin
• Values will be reflection of acute phase response
– Increased vascular permeability of the microvasculature
• Plasma proteins leak into interstitial space
– Reprioritization of hepatic protein synthesis
Energy Recommendations: Non-Obese
2016 SCCM/ASPEN Guidelines
• Indirect calorimetry (IC) should be used to determine energy requirements,
when available.
• In absence of IC:
– Published predictive equation
• > 200 exist; accuracy ranges from 40-75%
– Simple weight based equation: 25-30 kcal/kg (dry/actual body weight)
• Quality of evidence: very low
Basis of Indirect Calorimetry
Measurement of oxidation in the body à all energy derived from
oxidation
• Measurement of:
– O2 consumption
– CO2 production
– Calculation of respiratory quotient (RQ) = VCO2/VO2
– RQ denotes substrate utilization
• Measurement must be taken during “steady state” conditions
RQ: if at 1-1.2 it could suggest overfeeding
if at 0.7 suggest fat oxidation, if at 0.82: protein oxidation
if at 1- cho oxidation
Protein Recommendations: Non-Obese
2016 SCCM/ASPEN Guidelines
• Protein is most important nutrient for:
– Wound healing, supporting immune function, maintaining lean body mass
• For most critically ill, protein requirements are proportionately higher than
energy requirements
– Protein needs not easily met by provision of routine enteral formulations
• Hence frequent use of/need for protein modular
• 1.2-2_______ g/kg actual body weight per day
– Very low level of evidence
Nitrogen Balance: Theory
Used to evaluate the adequacy of protein intake
• N-balance studies reflect balance between exogenous N-intake and
renal removal of N-containing compounds
• Urinary urea nitrogen (UUN) increases dramatically in the sickest of
patients
– Reflects protein catabolism d/t inflammation, disease
• Theory: Increasing exogenous protein will reduce protein losses
– N-balance not a true measure of endogenous protein synthesis
Nitrogen Balance Equation
nitrogen balance = protein intake g/ 6.25 - unn excreation g +4g
Energy Recommendations: Obese Patients in ICU
2016 SCCM/ASPEN Guidelines
• Goal of EN / PN regimen should not exceed _65-70%_____ of target energy
requirements as measured by IC
– Rationale: Achieving some degree of wt loss via hypocaloric feeding may increase insulin
sensitivity, facilitate nursing care, reduce risk of comorbidities
• In absence of IC:
– BMI 30-50: __11-14_____ kcal/d ___actual ____ weight
– BMI > 50: 22-25kcal/kg ideal body weight
• In guidelines, no recommendation on how to calculate ideal body weight
• In Canadian ICU’s (anecdotal evidence): weight at BMI 25
Protein Recommendations: Obese Patients
BMI 30-40: 2.0 g/kg ideal body weight
• BMI > 40: up to 2.5 g/kg
• Protein recommendations should be adjusted using N-balance studies with a
goal of achieving nitrogen equilibrium if possible.
Permissive vs Hypocaloric Feeding
Permissive Underfeeding • Lower total nutritional intake including calories, protein and micronutrients • Can be mistakenly associated with hypocaloric feeding • Has not been shown to improve outcomes for ICU patients • Is NOT recommended in the ICU
Hypocaloric Feeding • Increased protein with lower overall caloric intake • Has been shown to be safe when used appropriately and allows for nitrogen balance • Associated with improved glycemic control, decreased ICU length of stay • Is current recommended practice in ICU patients
Hemodynamic Stability and Initiating EN/PN
• Definition: an abnormal or unstable blood pressure, especially
associated with hypotension.
• Can be defined more broadly as global or regional perfusion
that is not adequate to support normal organ function.
• Inotropes and vasopressors are medications given for
hemodynamic support
Inotropes
• Alter (increase) the force of energy of muscular contractions (i.e. of the heart) • Examples: – Dobutamine – Dopexamine
Vasopressors
Drugs that cause constriction of blood vessels • Examples: – Epinephrine – Dopamine – Phenylephrine – Norepinephrine (Levophed) – Vasopressin
Is EN Safe During Periods of Hemodynamic Instability?
Risk if feeding a hemodynamically unstable patient: bowel necrosis
• EN may be provided with caution to patients on chronic, low doses
of vasopressors
• EN should be withheld in patients:
– Who are hypotensive (MAP < 50 mm Hg)
– Catecholamine agents are being initiated
– Escalating doses of pressors required for hemodynamic stability
Monitoring Patients on EN & Vasopressors
Signs of intolerance should be monitored closely, specifically:
– Abdominal distention
– Increased NG output or GRV’s
– Decreased passage of stool or gas; hypoactive bowel sounds
• S/S closely scrutinized as possible early signs of gut ischemia
and EN held until symptoms/interventions stabilize
”Early” Enteral Nutrition
• Definition: Initiation of EN within 24-48h of ICU admission
• SCCM/ASPEN recommends nutrition support therapy in the
form of early EN be intiated in the critically ill patient unable to
maintain volitional intake
• Remember: patients who are mechanically ventilated via
endotracheal tube intubation cannot physically eat by mouth.
Benefits of Enteral Nutrition
Maintains gut integrity
• Modulates stress and the systemic immune response
• Attenuates disease severity
• Associated with positive outcomes (decreased infection rates,
decreased LOS, decreased rates of organ failure)
