Anaesthesia IV Week 1-6 Flashcards
What is a hypotonic solution?
The ECF has less solute and less osmotic pressure than what’s in the cells therefore water moves into the cell to attempt to balance solute concentrations.
The cell gets lysed (burst)
What is a hypertonic solution?
The solution has more solute and higher osmotic pressure than what’s in the cell therefore water moves out of the cell to dilute the solute.
The cell shrivels and crenates
What is an isotonic solution?
The fluid has the same concentration of solute and osmotic pressure as within the cell
What are the sodium and water requirements per day?
100-150 mmol Na
2-3 L water
(Usually 2500ml in and 2500ml out)
What is a crystalloid?
An aqueous solution of mineral salt or other water soluble molecules
A solution which mimics plasma
Contains electrolytes and small particles
What is a colloid solution?
Large insoluble molecules which cannot cross the membrane - exerts osmotic pressure causing fluid to remain in this space
Suspended in a solution
Increase the circulating volume
Longer effect than crystalloids - slower to break down
What is a problem with dextrose 5% solution?
The dextrose gets metabolised quickly leaving water (solution) in the ECF which is hypotonic. Therefore water moves into the cells and dilutes electrolytes (hyponatraemia)
What is the fluid replacement scheme?
40ml/kg/24hr
For replacement fluids
This can be increased by 15% for every 1 degree Celsius over normal temperature
What is the paediatric fluid replacement guideline?
The 4-2-1 regime
4ml/kg/Hr for each of the first 10kg
2ml/kg/Hr for each of the second 10kg
1ml/kg/Hr for each subsequent 1kg
Fluid: 0.45% NaCl/5% dextrose
Why are lactated ringers contraindicated when infusing blood?
Contains calcium.
Blood has an additive in it which prevents the RBCs from clotting by binding to the calcium. By adding calcium from the Hartmans solution, clots are able to form.
Why is it ok to give calcium during MTP?
Because most of the calcium in the blood is bound and the levels in the body are becoming low. By giving calcium, the heart becomes more efficient at contracting.
What fluids are contraindicated with blood products?
5% dextrose may induce haemolysis
Lactated ringers and gelofusine may induce clotting
Define haemolysis.
The destruction of RBCs
What is the fluid to blood ratio of the fluid groups?
Crystalloid: 3:1
It travels throughout the ECF whereas colloids have large insoluble molecules which encourages them to stay in the plasma compartment
Colloid: 1:1
What are the fluid compartments?
Total 60% (45L) fluid in body (75% child)
Intracelluar: 2/3 (28L) of the water (40%)
Extracellular: 1/3 (14L) of the water (20%)
- interstitial: 11L (3/4) of ECF
- plasma: 3L (1/4) of ECF
+/- colloids
Replace blood 1:1 Expands circulating volume High cost Can affect coagulation Large molecules don't cross membrane At high volumes the affects may reverse Anaphylaxis risk
+/- crystalloids
Replace blood 3:1 No allergy risk Water soluble molecules Electrolytes Mimics the plasma Low cost
What are the hazards of rapid infusion?
Air embolism Drug error Accidental bolus from fluid refluxing Tissue toxicity (incorrect IV) Phlebitis Anaphylaxis Temperature high or low Fluid overload Fluid contaminations Mechanical faults in lines Arterial injection
Describe the components of blood.
RBC: 45%
Plasma: 55%
Buffy coat (WBC, platelet) 1%
What is plasma?
The liquid part of the blood which contains antibodies and proteins
What are red blood cells?
Enucleated cells which contain haemoglobin capable of transporting oxygen throughout the body.
Last for 120 days
Also called erythrocytes
What is third spacing?
When too much fluid moves from the intravascular space to a transcellular space (a space somewhere in the body it shouldn’t be eg bowel lumen) where it cannot participate in fluid movement
What are normal blood volumes?
Normal blood volume is 70ml/kg (5L adult) and 80ml/kg child
What is the total body water?
60% men
50% women
75% child
TBW= 0.6 X weight (for a man)
Therefore 45L of water for a 70Kg man
What is extra cellular fluid?
All fluid outside the cells
What is interstitial fluid?
The fluid which surrounds the cells
What is transcellular fluid?
A part of the ECF and is contained in epithelial lined spaces
What is osmosis?
Diffusion of water across a semi permeable membrane from an area of low solute concentration to an area of high solute concentration
What is a fluid challenge?
100-200ml bolus of fluid
A sustained rise is CVP >3mmhg suggests the patient is well filled.
If not sustained rise, keep bolusing
What is hypernatraemia and the treatment?
High serum sodium
Treat with 5% dextrose (hypotonic)
What happens in untreated hypovalaemia?
Low perfusion Low oxygenation Organ damage Organ failure Death
What are colloids made of?
Albumin - protein
Dextran - polysaccharide (can affect cross match and clotting)
Gelatines - collagen
Starches - maize
What is a syringe pump?
Programmable Set infusion rate and bolus Maintain a constant infusion Mechanism: pulsatile continuous delivery 2.5% accurate Battery and mains Need Anti syphon valves prevent free flow Correctly engage syringe Shouldn't be >100cm above patient
What’s a burette?
A accurate fluid delivery device placed between bag and giving set
1ml divisions
High accuracy for volume infused
Ball valve prevents air entry
What are the protocol around blood infusing equipment?
Approved devices only Sterile sets 170-200 micron pore filter Prime with normal saline or product Change set every 4 units or 10 units in MTP or 8 hourly Need new set for platelets Don't add drugs to this line Warm if large/rapid volumes Keep below 41 degrees
Name 4 isotonic solutions.
Normal saline
Hartmans
Gelofusine
Volulyte
(Also plasmalyte, dextrose 5%)
Name 3 hypertonic solutions.
Saline 3%
Dextrose 10%
Mannitol
Name 3 hypotonic solutions.
- 45% saline
- 5% dextrose
- 18% saline
What is an acute haemolytic reaction?
Incompatible red cells react with patients antibodies
Can cause DIC and renal failure
Fever, rash, hypotension or sudden spike, oozing wounds, Hb in plasma or urine, difficult breathing, agitation
What is a bacterial contamination reaction?
Can be from IV site, skin plug, donor, processing contamination.
Signs of infection and sepsis
More likely in warmer products eg platelets
To reduce: check product bag and expiry, donor testing, disinfect donor skin, discard initial 10ml sample, monitor platelets with detection system
What is a DHTR?
Delayed haemolytic transfusion reaction
A haemolytic reaction >24hours after infusion
Secondary immune response
Commonly Jk or Rh
What is a NHFTR?
Non-haemolytic febrile transfusion reaction
Fever or rigors during transfusion
Slow/stop rate; give antipyretic
Can be mild to moderate
Washed cellular products may be better for these patients
What is a TRALI?
Transfusion related acute lung injury
When donor plasma has antibodies against patients leukocytes
Respiratory distress, hypoxaemia, pulmonary oedema, cyanosis, tachy, fever
Female donor with multiple children commonly have the antibodies (HLA, HNA)
What is a TACO?
Transfusion associated circulatory overload
Infusion too rapid or too much volume
Respiratory distress, tachy, high BP, distended neck veins
Treat with diuretic, O2, compress lower limbs, sit up
What reactions can occur with a blood transfusion?
Acute haemolytic Bacterial contamination DHTR NHFTR Allergy/anaphylaxis TRALI TACO Graft-vs-host disease (donor lymphocytes attack) Immunosuppression Post transfusion purpura (low platelets cause haemorrhage)
What biochemical reactions may occur from blood transfusions?
Hypocalcaemia from citrate binding to Ca
Hyperkalaemia (high potassium during storage)
Acid-base disturbances
Describe ABO blood typing.
A, B, AB, O
Determined by antigens on cell surface (agglulinogens)
Plasma contains antibodies to any antigens not present on cells
(Agglutinins)
What are the blood universals?
Donor: O- because it has no surface antigens to attack
Recipient: AB because these people have no antibodies to attack other blood groups
Why is recipient blood most important when blood matching?
Consider a patient who is AB blood group therefore have no antibodies. So we could give them a unit of A (which in theory would have B antibodies) because it is just RBC ie there isn’t plasma (which carries antibodies). A bag of RBC has a small amount of plasma that passes through but not enough to harm the patient.
CONSIDER DONOR ANTIGEN BUT RECIPIENT ANYIBODY
Describe the Rhesus factor.
Present +
Carries on RBC surface
Not spontaneously formed antibodies: Rh + never forms, Rh - may form antibodies from exposure
First exposure sensitises and second exposure causes reaction
Why is Rh a problem on pregnancy?
When there is a Rh- mother with a Rh+ child
First pregnancy is ok but mother gets sensitised at birth and produces Rh antibodies
During second pregnancy the mothers antibodies will attack the child
Mothers antiD crosses placenta and agglutinates babies RBC - death or brain damage
How is Rh problems treated?
Inject mother with anti D agglutinins to agglutinate Rh factor so mother can’t become sensitised
Inject at 28 weeks and after birth
What is the compatibility of the products?
RBC: must match
Platelet or cryoprecipitate: ideally the same but can differ
FFP: must match but remember it’s inverse to normal chart
What should be considered when giving O-?
Can use to start an emergency
Take G+H as soon as possible
Preferred no more than 4 units
Remember it’s precious and does contain some A and B antibodies!!!
What are the conditions of donation?
At an approved centre 16-60 y/o In good health >50Kg Complete paperwork Informed consent Test for ABO, antibodies and disease Leukodeplete (filter out WBC to reduce infection and affects) Labelled correctly
What is apheresis?
Process where a particular substance is removed and the rest is returned to the donor eg plasma
How must a sample be collected?
Check patient ID
Informed consent
Hand write blood tube
Collect and complete entire process in presence of patient with no interruption
How long are samples valid for?
Pt transfused/pregnant/Hx antibodies: 72 hours
None of above, in hospital: 7 days
None of above, pre admit clinic: 21 days
What is autologous donation?
Patient donates own blood prior to surgery
Includes:
pre operative collection - weeks before
Peril prestige acute haemodilution - immediately prior
Cell salvage
High cost, stringent planning, risk getting it wrong, weakens the patient, high waste, no haemolytic risk, bacterial risk remains
Describe pre operative autologous collection.
Patient donates a unit per week in the month before surgery.
Reduced transfusion risk
Bacterial risk remain
May need Fe supplement
Circulatory overload possible with whole blood
Describe perioperative acute haemodilution donation.
Patient donates whole blood immediately before surgery - replace volume with fluids - then return blood at the end providing clotting factors etc
Unstable patient
Less cost and less error risk
Storage correct in theatre
Describe cell salvage.
Hooked up to surgical suction; or from drains
Can replace close to what is lost
Endless
Debra risk - DIC
Need skilled staff
Cell destruction occurs
Can’t use with OBS - reinfuse fetal contaminants, not for bacterial contaminated sites, malignant disease
What is a directed donation?
A certain person is sought after and donates for a specific person
Doesn’t use bank supply, available quickly
Transfusion risks remain, increased GVHD of family, donor may not disclose, high cost, major planning
What are surgical techniques to reduce blood loss?
Radiology help Diathermy Laparoscopic LA with adrenaline Pre- surgical optimise eg iron Tourniquet
