IV fluids Flashcards
two categories of fluid spaces in body
intracellular space: 2/3 of fluid
extracellular space: 1/3 fluid
subdivisions of extracellular space
intravascular space (20%) intersitial space (80%) third space
what is 3rd space refering to
areas of body that do not normally contain fluid + where fluid collection is not desirable
e.g. peritoneal cavity (ascites), pleural effusion …
and
non-functional + excessive fluid in interstisial space –> oedema
third spacing
fluid shifting into non-functional 3rd space
often refers to development of oedema , asictes, effusions
sources of fluid intake
oral
NG/PEG feeds
IV
TPN
sources of fluid output
urine output bowel/stoma output (esp diarrhoea) drain output bleeding sweating
insensible fluid loss
fluid output that is difficult to measure e.g. through respiration
signs of hypovolaemia
hypotension tachycardia inc CRT cold raised resp rate dry mucous membranes reduced skin turgor reduced urine output sunken eyes thirsty
signs of fluid overload
peripheral oedema
pulmonary oedema
raised JVP
inc bodyweight from baseline
indications for IV fluids
resuscitation e.g. sepsis, hypovolaemia
replacement e.g. vomit + diarrhoea
maintenance e.g. NBM
two main groups of IV fluids
crystalloids
colloids
crystalloids
water with added salts or glucose
contents will redistribute throughout the different fluid compartments
crystalloids: 0.9% NaCl
1L water
154mmol Na
154mmol Cl
lot of sodium - risk hypernatraemia
crystalloids: 5% dextrose
1L water
50g glucose
lots of hypotonic (no electrolytes) fluid can result in hyponatraemia and oedema
crystalloids: 0.18% NaCl in 4% dextrose
1L water
31mmol Na
31mmol Cl
40g Glc
crystalloids: hartmann’s
1L water 131mmol Na 111mmol Cl 5mmol K 2mmol Ca 29mmol lactate
crystalloids: plasmalyte 148
1L water 140mmol Na 98mmol Cl 5mmol K 1.5mmol Mg 27mmol acetate 23mmol gluconate
what is risked using normal saline
hypernateamia
metabolic acidosis - lot of chlorine
colloids
contain larger molecules that stay in intravascular space
colloid - human albumin solution
used in pt w decompensated liver drains
tonicity
osmotic pressure gradient between 2 fluids
determines if water will move osmoticaly across membrane
isotonic solutions
match concentration of solutes (osmolality) in plasma
e.g. 0.9% saline, Hartmann’s, PlasmaLyte
hypotonic solutions
have lower concentration of solutes than the plasma
e.g. 5% dextrose, 0.18% NaCl
hypertonic solutions
have higher concentration of solutes than plasma
e.g. 3% saline
