IV fluids and Nutrition Flashcards
why is Hartmann’s solution preferred over 0.9% NaCl in surgery in relation to Cl- concentration?
concentration less in Hartmann’s (111mmol/L), and too much Cl- can lead to a hyperchloraemic metabolic acidosis developing in which increase in Cl- reduces HCO3-.
also, too much Cl- can cause vasoconstriction.
indications a ptnt may need urgent fluid resuscitation?
clinical assess: dry mouth, loss of skin turgor, sunken eyes, CRT>2s, cold peripheries RR>20 breaths/min HR>90beats/min systolic BP less than 100mmHg an early warning score of 5 or more
normal daily water requirement in maintenance fluids?
25-30ml/kg/day
normal Na+, Cl- and K+ requirement in maintenance fluids?
1mmol/kg/day
normal glucose requirement in maintenance fluids?
50-100g/day glucose
the 5 Rs of assessment and re-evaluation of a pt’s fluid and electrolyte needs?
resuscitation replacement routine maintenance redistribution reassessment
why is it so important to feed a bariatric ill pt on a ward as much or more than a normal well individual?
eventhough pt is overweight, he will not be mobilising his fat stores to provide energy. disease will mean his BMR is high, his hormones will be raised, so his hormone sensitive lipase will be low and once glucose consumed from blood and from glycogenolysis, muscle breakdown occurs to produce glucose.
Muscle Loss will provide significant immobility for pt, increasing bed stay, and reducing prognosis and recovery rate, Susceptible to LRTI with resp. muscle wkness.
best simple assessment of adequate nutrition in hosp in-pt?
BMI
serum albumin= good predictor of surgical outcome but correlates poorly with overall nutritional status as influenced by injury or illness
-ves of parenteral nutrition?
line sepsis
line thrombosis
metabolic imbalance e.g. acid-base disturbance, cholestasis- raised LFTs and ALP
some nutrients not available via this route e.g. short chain FA for colonic mucosa provided by bacterial degradation of fibre or carbohydrate.
intestinal mucosal atrophy?
mechanical injury e.g. pneumothorax
kcal in 1g of protein?
4
kcal in 1g of carbohydrate?
4
kcal in 1g of fat?
9
indications for parenteral feeding?
inadequate length of absorptive intestine intestinal obstruction severe mucositis severe sepsis producing ileus high-ouput entero-cutaneous fistula chronic intestinal pseudo-obstruction
in which pts might nasojejunal feeding be useful?
gastroparesis
pancreatitis
why is continuous drip feeding better than bolus?
bolus can lead to reflux and diarrhoea
gen. start at 30ml/hr
common indication for PEG?
inability to eat satisfactorily 2 wks post stroke
how is a PICC inserted?
via basilic vein at antecubital fossa, avoiding cephalic as it joins the axillary at a sharp angle making advancement beyond this point difficult.
what is a Hickman line?
central venous catheter used for feeding
placed via a SC tunnel from a point on the chest wall distant from point of entry of catheter into the vein.
g of protein in 1g of nitrogen?
6.25g protein
how can nitrogen loss be monitored?
check urinary urea excretion
why might there be initial weight loss in pt reintroduced to food?
if pt has oedema or ascites, as expanded EC space diminishes.
pts susceptible to refeeding syndrome- metabolic disturbance e.g. hypophosphataemia?
pts starved for more than 7 days
chronic alcoholics
pts with anorexia nervosa
pts who have lost >20% body weight in 3 mnths
why is a glucose infusion needed in liver failure?
failure of gluconeogenesis
considerations in feeding pts with acute pancreatitis?
was prev. though pts should be kept NBM and receive TPN to reduce pancreatic enzyme secretion, but this increases mucosal permeability and prolongs endotoxaemia.
infusion enteral feeds e.g. NG or NJ has little effect on pancreatic secretion and may reduce systemic inflam. response.
characteristics of refeeding syndrome?
hallmark feature= hypophoshataemia
may also feature abnormal sodium and fluid balance, changes in glucose, protein, and fat metabolism, thiamine deficiency, hypokalaemia and hypomagnesaemia.
L of fluid in ICF and ECF in average 70kg male?
ICF= 28L (2/3)
ECF= 14L (1/3)
IV= 3.5L
interstitial= 10.5L
why do females have less fluid as a % of their body weight than males?
females have relatively more adipose tissue which is assoc. with lower amounts of water
typical % of body weight which is water?
50-60%
why does the volume of the blood remain the same when fluid is lost via sweating during exercise?
fluid lost from sweating means fluid loss from intravascular compartment as blood going to the sweat glands enables the production of sweat, so intravascular compartment becomes more concentrated, the osmotic pressure increases, and fluid is drawn out from the interstitial compartment to keep the blood volume the same.
normal concentration of K+ in plasma?
3.5-5.3 mmol/L
why is increased K+ lost in serious injury and illness?
increased excretion from high cortisol and aldosterone levels, and to protein and glycogen metabolism- protein b.down into aa means loss of -ve charge from ICF, so K+ also moves out of cells to maintain electroneutrality.
what is the effect of giving glucose to malnourished pts, which can cause the features of refeeding syndrome?
glucose + release of insulin that occurs with it reverses depression of membrane pumps, increasing cellular uptake of K+, Mg2+, PO43- and Ca2+, which can cause dangerous falls in plasma levels.
also, same time net Na+ and water movement out of cells into circulation.
may be diminished cardiac reserve and high capillary permeability causing lethal fluid o.load and cardiac instability.
why does NICE recommend NOT to use the colloid tetrastarch in pt resuscitation?
now thought that crystalloids are actually retained more than expected in circulation and in ill pts retain less colloid (increased capillary permeability?)
Na+ content of 1L of normal saline (NaCl 0.9%)?
154mmol
problems assoc with repeated use of sodium chloride 0.9% (isotonic saline)?
Na+ and water retention, more oedema than colloid?
hyperchloraemia which can cause hyperchloraemic acidosis, GI mucosal acidosis and ileus.
benefits of using balanced crystalloid solutions e.g. Hartmann’s and Ringer’s in fluid resuscitation?
less Na+ and Cl- than isotonic saline, and already contain Ca2+, Mg2+ and K+.
contain lactate or other buffers which can help with significant acidosis often seen in circumstance of resuscitation.
usefulness of glucose and glucose saline solutions?
correcting or preventing dehydration
can meet routine maintenance needs when used with K+
risks with use of glucose and glucose saline solutions?
significant hyponatraemia if administered too quickly or too much fluid given
problems assoc with colloid use?
renal dysfunction
coagulation disturbance
physiological disturbance
what test can be used to assess if a pt is likely to respond to fluid therapy?
passive leg raise test- if pt’s BP improves following a passive leg raise, this is indicative of vol depletion.
in IV fluid management, what timing is initial IV bolus given over?
less than 15 mins
max IV fluid you can give in resuscitation before asking for expert hep?
2L
Easy way to assess skin turgor?
Pinch the skin together on the forehead and on the chest, and see how quickly the skin regains its original appearance.
risk with rapid reversal of hyponatraemia by giving IV fluids?
pontine myelinolysis= severe damage to myeline sheath of nerve cells in the pons, pt presents with dysphagia, dysarthria and paralysis.
NICE recommendation for prescribing IV fluids in resuscitation?
rapid infusion over less than 15 mins of a 500ml bolus of an isotonic crystalloid- Na+ 130-154 repeated, if necessary (250-500mL boluses) until markers of vol status improve.
if pt has received 4 boluses of IV crystalloid fluid resuscitation for hypovolaemic shock, and despite seemingly euvolaemic, still has low BP and high HR, what must be considered?
other causes of shock e.g. septic shock
need senior help and manage accordingly
risks of using high volumes of NaCl in fluid resuscitation?
hyperchloraemic acidosis
volume overload
difficulty in IV fluid replacement with variable output stoma?
giving IV fluids may be excessive if output from stoma falls, causing risk of pulmonary and peripheral oedema
if stoma output increases, IV fluid therapy without frequent reassessment may be insufficient, causing AKI.
also risk of hypokalaemia if inadequate K+ replacement given, and hyponatraemia espec. as likely to have high Na+ loss of stoma and so total body Na+ depletion as well as high ADH due to hypovolaemia and nausea in some pts, so urinary Na+ monitoring would be useful.
what should an IV fluid management plan detail?
fluid and electrolyte prescription over the next 24 hrs and monitoring requirements including daily reassessments of clinical fluid status, lab values-urea, creatinine, electrolytes, and fluid balance charts, and weight measurement twice wkly.
how can a pts IV fluid therapy needs for routine maintenance alone be managed?
pt needs 25-30 ml/kg/day of fluid, 1mmol Na+/K+/Cl- and 50-100mg glucose.
consideration in timing of IV fluids for routine maintenance?
consider delivering during daytime hrs to promote sleep and wellbeing.
in which pts might you consider prescribing less fluid than normal for routine maintenance?
older pts
pts with renal impairment/cardiac failure
malnourished pts at risk of refeeding syndrome
elderly pt with normal cardiac function given IV fluids for routine maintenance. what are the risks?
hyponatraemia if excessive hypotonic fluids are given
volume depletion if insufficient Na+ and water given
volume overload if excessive Na+ and water given
AKI if inadequate Na+ and water given
NICE guidance for initial IV fluid prescription for routine maintenance for a 70kg pt over 24hrs?
1.75-2.1 L of sodium chloride 0.18% in 4% glucose with K+ on day 1
if a pt receiving IV fluid therapy for routine maintenance, what must be considered after 24 hrs?
whether their fluid and electrolyte requirements are being met, if not may discuss with a senior the need for nasogastric or PEG feeding, or continuing IV fluids
if further IV fluid therapy indicated check vol status, fluid balance chart and weight, serum urea, creatinine, Na+ and K+, and alter rountine maintenance prescription accordingly. seek advice from senior if in doubt.
recommended contents of an IV fluid management plan?
Pt fluid an electrolyte requirements over the next 24 hrs, with reference to the 5 Rs
Pt volume assessment details
intended fluid prescription
monitoring requirements
when the plan is to be reviewed, and by whom
plan should be drawn up where possible in consultation with the pt and/or their family/carers. pt should understand why IV fluids are needed and be aware of what to look out for if fluids too much or insufficient. written info should be provided where possible, and plan should be communicated well with all of those involved in looking after the pt.
aslo include when to review, frequency of observations and measures to reduce need for IV fluids
current position regarding colloid prescription?
hydroxyethylstarch (HES) solutions should not be prescribed to treat sepsis, burn injuries of critically ill pts as increased risk of kidney injury and mortality.
when should IV fluids be stopped?
as soon as pt can meet their fluid and electrolyte needs orally or enterally
what is normal urine output?
1ml/kg/hr, with minimum of 0.5ml/kg/hr
likely urea: creatinine ratio in hypovolaemia?
> 100:1
as both freely filtered at glomerulus but enhanced reabsorption of urea at PCT is hypovolaemic.
how many ml of fluid are lost as insensible losses daily?
500 ml
parameters to observe when determining a pt’s fluid status?
BP and postural changes HR RR CRT skin turgor mucous membranes-dry/moist, pink/pale? fluid balance charts presence of peripheral or pulmonary oedema Us and Es JVP thirst NEWS (national early warning score)
most useful immediate observations to assess fluid status of a pt?
mucous membranes CRT BP HR urine colour
causes of volume depletion in sick pts?
vomiting diarrhoea not drinking enough fluids high output GI stoma DM DI diuretic use burns trauma
importance of BMI in calculating pt’s fluid requirements?
if obese, requirements should be calculated based on ideal body weight and not actual body weight
Pts at risk of complications of IV fluid therapy?
elderly/frail low BMI obese multiple co-morbidities HF renal impairment-grade 3A or worse liver disease/cirrhosis diabetes 48-72 hrs post surgery unconscious
consequences of fluid mismanagement to be reported as critical incidents?
pulmonary oedema peripheral oedema hyponatraemia hypernatraemia hypokalaemia hyperkalaemia hypovolaemia
others= thrombophlebitis and arrhythmias
classical presentation of refeeding syndrome?
acute congestive cardiac failure precipitated by fluid shifts occurring from reintroduction of carb after prolonged starvation.
biochemically= reduction in phosphate, potassium and magnesium.
cardiac, respiratory, GI and neurological function impaired.
consequence of reduced phosphate in refeeding syndrome?
arrhythmias acute resp failure confusion HF lethargy rhabdomyolysis seizures
consequence of reduced potassium in refeeding syndrome?
arrhythmias cardiac arrest polyruia/polydipsia resp deression ileus wkness
consequence of reduced magnesium in refeeding syndrome?
arrhythmias confusion altered bowels ataxia muscle tremors wkness
NICE RFs to identify pts at high risk of refeeding syndrome?
1 or more of:
BMI less than 16
unintentional weight loss more than 15% within last 3-6mnths
little or no nutritional intake for more than 10 days
low levels of potassium, phosphate or magnesium prior to feeding
or 2 or more of:
BMI less than 18.5
unintentional weight loss >10%
little or no nutritional intake for more than 5 days
history of alcohol abuse or drugs including insulin, antacids, diuretics or chemotherapy.
rapid weight loss= biggest RF
explain the metabolic processes occurring in the starvation state and then what happens to result in the refeeding syndrome?
prolonged starvation: insulin drops, activating hormone sensitive lipase- fat stores broken down. FA used in KB prod and glycerol for gluconeogenesis. Muscle also broken down to aa for gluconeogenesis. And phosphate stores depleted.
Carb reintroduction- insulin rapidly increases for glycogen, fat and muscle synthesis from glucose. This requires phospahte, and drives phosphate, potassium, magnesium and water into tissues, and sodium out.
subsequent oedema and
low phosphate reduces ATP prod. impairing cardiac muscle function
and reduces 2,3-DPG in red cells, reducing tissue oxygenation
thiamine use also increased.
how is refeeding syndrome prevented?
diet re-introduction at SLOW rate, e.g. as low as 5-10kcal/kg/day in anorexic pts.
IV phosphate infusion before feeding
parenteral multivitamins as important in carb metabolism
rigorous checking of phosphate, potassium and magnesium levels.
