11: Nutrition - A Clinical Pharmacist's perspective Flashcards
Malnutrition in hospital
- Debilitating & reported rates up to 40%
- Associated with adverse outcomes
+ Impaired would healing
+ Muscle wasting
+ Increased length of stay
+ Increased mortality - Poorly documented
- Loss of appetite
- Patients go nil by mouth
+ Various tests
+ Procedures
+ Operations - Gastrointestinal diseases
+ Crohns
+ Ulcerative colitis
+ Intestinal failure
Ileus
Lack of digestive propulsion (movement) of the gut
- Surgery
- Sepsis (shock)
- Electrolyte imbalance
- Medications
- Various diseases (Crohns, UC, Parkinsons)
Prokinetics (3)
Agents that increase gastric emptying
- Usually initiated when gastric residual volumes >~250 ml day
- Metoclopramide
- Dopamine D2 Blocker & 5HT4 agonist
- 10 mg IV QID
- Precautions: EPSE (elderly/adolescent), QT prolongation - Erythromycin
- Motilin agonist
- 100-250 mg IV QID
- Precautions: QT prolongation - Domperidone
- Dopamine D2 blocker
- 10 mg PO QID
- Precautions: Oral formulation only
Drugs down feeding tubes
- Medications are NEVER mixed into bags of feeds
- Each medication must be administered separately
+ Incorrect medication administration is a frequent cause of tube blockage
Medications that require
- EMPTY STOMACH
+ Feeds stopped 30-60 minutes before administration
- Medication is INCOMPATIBLE with the feed:
+ Stop the feed for 2 hours before & 2 hours after the medication administration
Fluids
- Total body water is ~60%
- Intracellular ~2/3
- Extracellular ~1/3
+ Interstitial fluid
+ Intravascular volume
Crystalloids
- Contain small molecules that pass freely through semi permeable membranes
- E.g. Normal saline, Dextrose, Plasmalyte
Colloids
- Contain large molecules which are too big to diffuse through blood vessels
- Stay in plasma & used as plasma expander in shock/trauma
- E.g. Gelofusin, Albumin, Pentastarch
“Normal” Saline 0.9%
- Usually see 0.9% NaCl (also 0.45 & 1.8%)
- ~154 mmol/L of Na & Cl per litre
+ Na-average adult needs ~1-2 mmol/kg/day
+ May cause acidosis as the chloride concentration is higher than plasma concentrations
Dextrose (Glucose)
- Usually Dextrose 5% (also 10-50%)
- Permeable through all membranes
- Will push patients to hyponatremia
- 1L dextrose 5% gives 200 kcal
Plasmalyte
Composition
- Na: 140 mmol/L
- K: 5 mmol/L
- Mg: 1.5 mmol/L
- Cl: 98 mmol/L
- Distributed in extracellular fluid
- Usually used in patients with fluid & electrolyte los
- Advantage of less chloride than 0.9% saline
- Most similar to plasma
Albumin
- Most used/common Colloid
- Have 4-20% Albumin bottles
- Not used for patients with low Albumin due to malnutrition as it is cleared in ~2-3 days
- Albumin 20% draws peripheral oedema from interstitial space to intravascular space
- SAFE trial found no better evidence to that of colloids & totally contraindicated in head injuries
- However showed benefit in patients with sepsis
Electrolytes: Potassium
- Intracellular electrolyte
- Reference range 3.5-5.2 mmol/L
- Patients usually hypokalaemic than hyper
+ Mild: 3.1-3.5 mmol/L
+ Moderate: 2.5-3.0 mmol/L
+ Severe <2.5 mmol/L - Need to assess the cause of potassium change, not just treat
Note: Lab results don’t reflect the “true” potassium levels
Replacement options
- Oral: Cholrvesent: 14 mmol per tablet
+ Slow K: 8 mmol per tablet
- IV: Potassium chloride
+ Max concentration of 40 mmol/L through peripheral line
+ <10 mmol/hr rate unless with telemetry or specialised unit
Phosphate
- Intracellular electrolyte
- Levels can ‘jump’ around a lot
- Reference range: 0.7-1.5 mmol/L
- Severe < 0.4 mmol/L
- Oral treatment: Phosphate Sandoz
+ 16.1 mmol per tablet - IV treatment: Potassium dihydrogen phosphate 10 mmol/L in 250 ml fluid & given over 6-8+ hours
+ Also have sodium formulation - Infusion of Phosphate can be given faster (2 hours) but increases likelihood of hypocalcaemia/phosphate toxicity
Magnesium
- Intracellular electrolyte
- Mild or asymptomatic hypomagnesia can be treated with oral supplements
+ Reference range 0.75-1 mmol/L
+ Severe < 0.4 mmol/L - Look for low Ca2+ & K+
- CMDHB Protocols available covers
+ Hypomagnesaemia, ventricular arrhythmias, severe asthma exacerbations, cardiac arrest
Oral:
- Mylanta: 200 mg/10 mLs [Mg(OH)2]: 20 mLs TDS
- MgOH2 tablets 311 mg (milk of magnesia): 2 BD
- Magnesium hydroxide mixture 8% mixture – compounded product
Intravenous
- 10-20 mmol/L in 50-100 mLs dex/NS over 20-60 minutes
- Oral formulations can cause diarrhoea (osmotic laxative)
- If patient is symptomatic (weakness, tremors, convulsions, arrythmias), IV route is preferred
What is refeeding syndrome?
Electrolyte & fluid shifts associated with metabolic abnormalities in malnourished patients undergoing re-feeding
So how do we minimise risk?
- Thiamine/Multivitamin preparation
- 50% of target feed (or reduced)
- Replace electrolyte fluctuations (K, PO4, Mg)
