Fluids Flashcards
surgical pts receive _% of transfused allogenic blood in the UK?
40
what is the purpose of a RBC transfusion?
improve O2 carrying capacity of blood
what are indications for RBC transfusion?
Hb < 70g/L - strongly indicated
Hb < 50g/L - essential
Hb 70-100g/L - unclear
symptomatic pt should be transfused, but cardiopulmonary reserve should be assessed
at what rate should transfusion be given?
according to rate of according loss
how is a decision to transfuse made?
individual pt basis - not all pt agree
pt need not be transfused to achieve normal [Hb]
what factors should be considered when deciding to RBC transfuse pt?
- cause and severity of anaemia
- pt ability to compensate for anaemia
- rate of ongoing blood loss
- likelihood further blood loss
- risk of CAD
- risk v benefit of transfusion
risks of RBC transfusion?
immediate immune or non-immune reaction
delayed immune or non-immune reaction
examples of immediate immune reactions?
acute haemolytic transfusion - abo incompat
febrile non-haemolytic transfusion rxn
allergic rxn
TRALI
examples of immediate non-immune reactions?
volume overload
ARDS
massive transfusion complications
bacterial infection
examples of massive transfusion complications?
coagulopathy
hypothermia
hyperkalaemia
acidosis
citrate toxicity
examples of delayed immune reaction?
GVHD
delayed haemolytic transfusion rxn
alloimmunisation
examples of delayed non-immune reaction?
viral infection (HIV, HBV, HCV, CMV, vCJD)
iron overload
what else is needed, besides RBCs, to achieve haemostasis?
platelets
clotting factors
fibrinogen
indications for platelet component therapy?
consider endogenous platelet function + count
if > 10 x 10^9/L in absence of active bleeding, no need to transfuse as patients are considered stable
if < 50 x 10^9/L and invasive procedure OR actively bleeding pt, then need to transfuse to increase count to above this value
how much does each dose of platelet bag increase the platelet count by?
~20 x 10^9/L in most adults
what is the volume of a typical unit of FFP?
150-200ml
how is FFP stored?
frozen - so need to factor in thawing time when ordering (20 mins)
what does FFP contain?
all clotting factors + components of fibrinolytic and component systems
indications of FFP?
empirically for acquired coagulopathy (prolonged INR or APTT):
- therapeutically when bleeding
- prophylactically in non-bleeding prior to surgery/invasive procedures
what is cryoprecipitate?
cryoglobulin fraction of plasma
contains fibrinogen (150-300mg), factors 8 and 13, vWF
indications for cryoprecipitate?
acquired coagulopathy related to haemorrhage, trauma, sepsis
what is the aim in cryoprecipitate therapy?
keep fibrinogen > 1.5g/L
dose of cryoprecipitate therapy?
usually 10 pack dose - contains 1.5-3g fibrinogen
which patient groups are prediposed to bleeding?
liver disease
renal disease
congenital coagulopathy
taking antiplatelet or anticoagulant drugs
Jehovah’s witnesses
define ‘massive haemorrhage’?
loss of 1 blood volume within 24h
50% blood volume loss within 3h
rate of blood loss of 150ml/min
what is the bloody vicious cycle?
haemorrhage -> resus -> haemodilution + hypothermia + acidosis -> coagulopathy -> haemorrhage etc
what must be avoided in management in massive haemorrhage?
avoid haemodilution, hypothermia, acidosis by managing aggressively and appropriately
what are the aims of management of massive haemorrhage?
hb > 80g/L
platelet count > 75 x 10^9/L
PT and APTT < 1.5x mean control
fibrinogen > 1.5g/L
avoid DIC
when should you anticipate platelet count < 50 x 10^9/L in mx of massive haemorrhage?
after 2x volume replacement
what is done if ?DIC
treat underlying cause if possible
what is the procedure to restore circulating volume?
wide bore peripheral cannula (14G or more)
give enough warmed crystalloid/colloid/blood
aim to maintain normal BP and UO (>30ml/hr)
monitor CVP
keep pt warm
blood loss is often underestimated!
examples of crystalloids?
hartmann’s
saline
5% glucose
4% glucose with 1/5 saline
examples of colloids?
gelofusion
geloplasma
how do crystalloids work?
contain water + electrolytes (most isotonic with ECF)
pass freely through semipermeable membranes
where will saline-based crystalloids (e.g. hartmann’s) distribute?
within exctracellular space
why is 5% glucose not recommended in fluid resus?
effectively giving free water because glucose is metabolised and the restulting water restributes into all the compartments (going mainly intracellularly)
how are colloids different to crystalloids?
are larger molecular wt substances (e.g. gelatins/starches) suspended (not disolved) in carrier solution
don’t pass through semipermeable membrane
stay in IVC longer
examples of carrier solution used in colloids?
saline (e.g. gelofusion, voluven)
hartmann’s-like (i.e. balanced, e.g. geloplasma)
colloids are ____ readily filtered at the kidney than crystalloids
less
complications of starch colloid?
excess renal complications and mortality compared to crystalloids
now only gelatin colloid and crystalloids used in UK
advantages of crystalloids to colloids?
cheap
easy to manufacture and store
long shelf life
no anaphylactic rxn
advantages of colloids to crystalloids?
smaller volume of infusion needed
remain longer in intravascular space
disadvantages of colloids to crystalloids?
more expensive
small risk of anaphylaxis
what + how much fluid in theatre?
500ml resus bolus (saline/hartmann’s) over 15 min - repeat 4x if needed
maintenance doses per NICE
hx of hypovolaemia?
vomiting, diarrhoea
intestinal obs
fluid intake reduced
thirst
clinical signs of hypovolaemia?
low UO
increased CRT
tachy
postural HTN - late sign
decreased consciousness
low CVP
lab markers of hypovolaemia?
raised haematocrit
increased serum lactate
increased urea disproportionate to creatinine
metabolic acidosis
increased plasma osmolarity
SV rises on colloid challenge
