Fluid management Flashcards
1
Q
What volume and proportion is total body water (TBW) in a 60kg person?
A
42L, 60%
2
Q
What volume and proportion is ICF (intracellular fluid) n a 60kg person?
A
28L, 40%
3
Q
What volume and proportion is total ECF (extracellular fluid) in a 60kg person?
A
14L, 20%
4
Q
What 2 componenets make up ECF and what volumes are each?
A
Interstitial fluid: 10L
Intravascular fluid: 4L
5
Q
What happens to age/ gender related changes in total body water with age?
A
As a baby TBW decreases; from teenage years it decreases more rapidly in females than in males. Continues to decrease this way into old age
6
Q
What are 2 broad causes of fluid shifts?
A
- Between body and outside world: intake and output
- Between fluid compartments: osmosis, diffusin and active transport
7
Q
What is the definition of osmosis?
A
Movement of solvent - water - across a membrane to a region of higher concentration of solute. Rate of movement depends on the number of particles in solution
8
Q
What are the definitions of osmolarity and osmolality - how do they differ?
A
- Osmolarity = number of osmoles per litre
- Osmolality = number of osmoles per kg
- Osmolarity is within Ls, osmalality in kgs
9
Q
What do osmoles express?
A
Osmotic activity
1 osmole of solute dissolved in 1kg of solvent has osmolality of 1 osmol/L (often given milliosmoles/L)
10
Q
What is the equation used to work out plasma osmolality?
A
Plasma osmolality (Posm) = 2[Na] + glucose + urea
11
Q
What is the usual physiological plasma osmolality?
A
290 mosmol/kg
12
Q
Why is there extreme hyperosmolatity in hyperglycaemic hyperosmolar state in diabetes?
A
Sodium, glucose and urea all go up in this state
13
Q
What is the definition of tonicity?
A
osmolality of a solution relative to plasma
14
Q
What happens to blood in a hypertonic solution?
A
Red cells shrink - if didn’t mix with rest of blood
15
Q
When is a hypertonic solution sometimes used?
A
For emergency resuscitation
16
Q
What is an example of a hypotonic solution?
A
Distilled water
17
Q
What happens to blood in a hypotonic solution?
A
Red cells lyse - fatal if large amounts injected
18
Q
What happens to red cells in an isotonic solution?
A
They are OK
19
Q
What are 2 examples of isotonic solutions?
A
- 5% glucose in water
- 0.9% NaCl
20
Q
Which compartment do people lose fluid from, predominantly?
A
Extracellular fluid
21
Q
What are 3 sources of fluid influx during a normal day?
A
- 1.3L from drinking
- 800ml from food
- 400ml from metabolism
Total: 2.5L
22
Q
What are 4 sources of fluid loss during the day?
A
- 500ml through skin
- 400ml through lungs
- 1500ml through urine
- 100ml through faeces
(total: 2.5L)
23
Q
What are the 2 groups that IV fluids are conventionally divided into?
A
Crystalloids and colloids
24
Q
What is a crystalloid?
A
Sterile mixture of water with salt or sugar, or a mixture of both salt and sugar. Contain only small molecules
25
What are 2 advantages of crystalloids?
1. Safe; low incidence of anaphylaxis
2. Cheap
26
What is the half life like of crystalloid solutions and how are they excreted?
Short intra-vascular half-life, excreted via kidneys
27
What are 3 examples of crystalloids?
1. 0.9% NaCl
2. 5% dextrose
3. Hartmann's (loved by anaesthetists, often used in theatre)
28
What happens when 0.9% NaCl is given?
Distributes entirely to the ECF
interstitial : intravascular 2:1 --\> 1L expands interstial volume by 666ml, and intravacsular by 333ml
29
What is the sodium content of 0.9% NaCl compared with physiolgical levels?
150mmol/L in 0.9% NaCl; plasma concentration is 137-142mmol/L
30
What happens when 5% dextrose is given?
Distributes to _all_ compartments following metabolism of the glucose; **_small_** impact on circulating volume
i.e. if 1L given, ICF expands by 666ml and ECF by 333ml (as ICF:ECF volume is 2:1). Within ECF, interstitial : intravascular is 2:1 so about 100ml will end up intravascularly
31
How does Hartmann's solution compare to other crystalloid solutions?
much more physioogical than saline or 5% dextrose (contains sodium, chloride, lactate, potassium, calcium). Stays in circulation for around same time as saline. Often used in theatre
32
What are the 5 elements in Hartmann's?
1. **Sodium** 131mmol/L
2. **Chloride** 111mmol/L
3. **Lactate** 29mmol/L
4. Potassium 5mmol/L
5. Calcium 2mmol/L
33
What are colloid solutions?
Large molecular weight compounds, used for plasma expansion
34
What are 4 examples of colloid solutions?
* **Non-synthetic** (less used): human albumin serum (HAS)
* **Synthetic**: gelatin, dextran, starch (suspended in isotonic fluid e.g. NaCl)
35
How does the half life of colloids compare to crystalloids?
Longer intra-vascular half life than crystalloids
36
What happens when colloids are given?
1:1 volume replacement
37
What are 4 problems with synthetic colloids (not HAS)?
1. **Anaphylaxis**
2. Affect coagulation (**anti-thrombotic**)
3. Deposit in reticulo-endothelial system (**pruritis**) - especially starches, itchy
4. **Renal** function (starch)
38
What are 2 features of the patient history suggesting fluid status (partiularly dehydration)?
Protracted period of polyuria
39
What are 6 features of examination that can point to fluid status?
1. Mucous membranes
2. Skin turgor
3. Capillary refill
4. JVP
5. Blood pressure
6. Urine output (reduced if extreme change)
40
What are the 3 stages of dehydration and what percentage and volume are lost in each?
1. **Mild** - 4% of TBW, **3L** - reduced skin turgor, dry membranes
2. **Moderate** - 5-8%, **4-6L** - oliguria, tachycardia, hypotension
3. **Severe** - 8-10%, **7L** - CVS compromise, confusion/coma
41
What are 3 investigations to help determine fluid status and what can they show?
1. FBC - haemoconcentration, anaemia, transfusion requirement
2. U+Es = sodium and urea elevated, urea: creatinine ratio can change in dehydration and renal failure
3. Creatinine - unaffected in just dehydration
42
Why can it be difficult to interpret FBC to work out if dehydration is present?
Difficult if blood loss and dehydration at same time - haemoconcentration may seem normal
43
What happens to all infused sodium in the body?
remains in ECF
44
What happens to water when entering the body?
Expands entire TBW
45
How does dehydration affect the fluid compartments in acute illness?
Almost uniform
46
What is the only indication for 5% dextrose/ glucose and when should it never be used?
Only indication is dehydration/prevention: do not give if bleeding as will give generalised body oedema
47
What is the treatment for hypovolaemia?
Rapid infusion of an isotonic solution: Hartmann's or colloid
48
What is the treatment for concelealed/ sequestered fluid losses?
Replace with normal saline
49
How should a TBW deficit be treated?
Replace with 5% dextrose
50
What are the maintenance requirements for a patient who is not eating or drinking e.g. in peri-operative phase?
1.5ml/kg/hour - otherwise will become dehydrated
51
What are the daily sodium and potassium requirements of the average person?
Sodium: 2mmol/kg/day
Potassium: 1mmol/kg/day
52
What is very important to remember to give post-operatively?
**Potassium**: some patients not given potassium even when they have normal renal function, and become **hypokalaemic**
53
How should potassium replacement occur if a patient is asymptomatic?
Correct slowly; 20-40mmol of KCl/ L of 0.9% saline
Re-estimate U+Es frequently
54
How should potassium levels be kept in arrhythmias?
Aim for high normal levels
55
What is the management of urgent fluid therapy?
ABC approach
**_14g IV_** (orange) **_venflon_**, preferably 2
Do not delay for investigation
**_2000ml normal saline or 1000ml colloid STAT_**
Reassess fluid status
56
What are 7 types of blood products?
1. Whole blood
2. Fresh frozen plasma (FFP)
3. Cryoprecipitate
4. HAS (human albumin serum)
5. Platelet-rich plasma
6. Platelet concentrate
7. SAG-M (saline adenine glucose and mannitol re-suspension of) red blood cells
57
How is donated whole blood given?
Large needle in antecubital fossa, goes into bag containing anticoagulant (blood increasingly separated on site)
58
How frequently is donated whole blood given?
Rarely
59
When is the highest proportion of blood used in the UK?
General surgery
60
What are the 6 constituents of blood?
1. Water
2. Electrolytes
3. Proteins
4. RBCs
5. WBCs
6. Platelets (platelets + white blood cells = buffy coat)
61
How is plasma made?
Centrifuging blood and removing RBCs and buffy coat. Can be treated in 2 ways: frozen to form fresh frozen plasma or turned into human albumin solution
62
What 2 key things are contained in fresh frozen plasma?
1. Plasma proteins
2. Labile clotting factors (stabiliised when frozen)
63
At what temperature is FFP stored and for how long can it be stored?
-30oC, \>1 year
64
Does FFP need to be cross-matched and why?
No, no red blood cells, ABO and Rh compatible
65
What volumes of FFP are given?
250-300ml
66
Why is there controversy over the use of HAS?
expensive, but old studies suggest it **decreases** mortality
67
What is the HAS (human albumin serum)?
This is the primary protein present in human serum (comes pasteurised, in glass bottles. flexible packs)
68
Which 2 types of surgeons like to use HAS?
liver transplant and cardiac surgeons
69
How many donations of platelets can one adult provide?
8-10
70
How are platelets stored and how long can they be stored for?
22oC, continuously agitated (to stop clots) for 5 days only
71
Within what period of delivery must platelets be used?
1 hour
72
What mustn't be done with platelets?
Refrigerated
73
Are platelets ABO and Rh compatible?
Yes
74
What is the difference between SAG-mannitol blood and whole blood?
no clotting factors, no platelets
75
How is SAGM blood stored and for how long?
Stored at 4oC, 28-35 days storage. Exists re-suspended, to keep it healthy
76
When is a massive transfusion given?
Patient has lost total circulating blood volume in 24 hours (8 units)
77
What are the 4 things given in a massive transfusion?
1. SAGM-RBC
2. FFP
3. Platelets
4. Cryoprecipitate
78
What is there a risk of when giving FFP and how can this be treated?
citrate toxicity: binds calcium and patient will become **hypocalcaemic;** given calcium chloride if calcium is low
79
When should a blood warmer be used to give blood?
When giving blood quickly; not apropriate for a unit over 2-3 hours in someone who's anaemic, but used for massive transfusions in operating theatre/ED
80
What do blood filters do?
* Remove white blood cells
* thought to be important for cardiopulmonary bypass (CPB) - reduces inflammation
81
What action should be taken before surgery during which the chance of transfusion is **unlikely**?
Group and save blood
82
What action should be taken before surgery during which the chance of transfusion is **likely**?
Cross-match 2 units
83
What action should be taken before surgery during which the chance of transfusion is **definite**?
Cross-match 4-6 units
84
What are 5 examples of surgeries during which the chance of a blood transfusion is **unlikely**?
1. Hysterectomy (simple)
2. Appendicectomy
3. Thyroidectomy
4. Elective lower segment caesarean section
5. Laparoscopic cholecystectomy
85
What are 2 examples of surgeries during which the chance of a blood transfusion is **likely**?
1. Salpingectomy for ruptured ectopic pregnancy
2. Total hip replacement
86
What are 6 examples of surgeries during which the chance of a blood transfusion is **definite**?
1. Total gastrectomy
2. Oophorectomy (ovary removal)
3. Oesophagectomy
4. Elective AAA repair
5. Cystectomy
6. Hepatectomy
87
What are 2 uses for packed red cells?
1. Transfusion in **chronic anaemia**
2. Cases where infusion of _large volumes of fluid_ may result in **cardiovascular compromise**
88
How are packed red cells obtained?
Centrifugation of whole blood
89
What is the main use of platelet-rich plasma?
usually administered to patients who are thrombocytopenic and are bleeding or require surgery
90
What is the difference in the way platelet-rich plasma and platelet concentrate are prepared?
Platelet-rich plasma is obtained by low speed centrifugation, but platelet concentration is high speed
91
What is platelet concentration used to treat?
Thrombocytopaenia
92
What does fresh frozen plasma contain?
clotting factors, albumin and immunoglobulin
93
What is the volume of a typical unit of fresh frozen plasma?
200-250ml
94
What is the use of FFP and what should it not be used for?
* usually used in correcting clotting deficiencies in patients with hepatic synthetic failure who are due to undergo surgery
* should not be used as first line for hypovolaemia
95
How is cryoprecipitate made?
formed from supernatant (liquid overlying crystallised solid at bottom) of FFP
96
What does cryoprecipitate contain and what is it used for?
Rich source of **factor VIII** and **fibrinogen**, allows large concentration of **factor VIII** to be administered in small volume
97
What is SAG-mannitol blood?
**removal of all *_plasma_*** from a blood unit and substitution with:
* **s**odium chloride
* **a**denine
* anhydrous **g**lycose
* **m**annitol
98
What is the maximum amount of SAGM blood that can be given and what must be done after this?
* Up to 4 units; thereafter, whole blood is preferred.
* After 8 units, clotting factors and platelets should be considered
99
What are the 4 types of blood that must be cross-matched?
1. packed red cells
2. fresh frozen plasa
3. cryoprecipitate
4. whole blood
100
What should _preferably_ be matched in platelets?
ABO matching - can be incompatible
101
What is the danger of giving excessive normal saline post-operatively?
In oliguric patients, can develop **hyperchloraemic acidosis**
102
Why are electrolyte-balanced solutions (e.g. Ringers lactate/ Hartmans) preferred to be given post-operatively over normal saline?
Reduces risk of hyperchloraemic acidosis
103
What are 3 key rules for post-operative fluids in surgical patients?
1. Fluids given should be documented clearly and easily available
2. Assess patient's fluid status when they leave theatre
3. If patient is haemodynamically stable and euvolaemic, aim to *restart oral fluid intake as soon as possible*
104
When should you review a post-operative patient regarding their _urinary_ electrolytes?
when sodium is \<20
105
How should an oedematous post-operative patient be treated?
Treat hypovolaemia first if present, followed by a negative balance of sodium and water, monitored using urine Na excretion levels
106
What group should solutions such as Dextran 70 be used with caution in and why?
patients with sepsis, due to risk of developing acute renal injury
107
What are the 5 steps to giving a blood transfusion?
1. Collect initial blood sample
2. Prescribe the blood transfusion
3. Check blood transfusion
4. Administer blood
5. Monitor patient
108
What does collecting the initial blood sample for a blood transfusion involve? 6 steps
1. ask patient name and DOB, compare to identity bracelet
2. collect sample into appropriate bottle for blood group (often pink)
3. copy patient details frmo identity bracelet onto bottle **AT BEDSIDE**
4. Sign blood bottle (confirm you obtained sample)
5. Complete corresponding **blood transfusion form**
6. Send bloods to lab for analysis of blood type and cross-matching if required
109
What are the 5 steps to prescribing a blood transfusion?
1. prescribe each unit of blood separately
2. document this accurately: often prescribed on fluid balance chart, "**PACKED RED CELLS**", docuement time and date and reason
3. Unit of blood is transfused **over 2-3 hours** if non-urgent
4. Arrange ot have blood delivered to ward
5. Blood needs to be given within **30 minutes** of leaving the refrigerator
110
Within what period of time do packed red cells (blood transfusion) need to be given after being delivered to the ward?
30 minutes
111
What are the 5 steps of checking the blood transfusion?
1. Request another nurse or doctor to go through procedure with you
2. Ensure patient details on bracelet, notes and blood compatibility report all match exactly (**important**)
3. check blood group and serial number on blood bag matches compatibility report
4. check expiry date and time of unit of blood to ensure it has not expired
5. inspect blood bag for: signs of tampering, leaks, discolouration, clots - do not administer if any notes
112
What are 4 things to inspect the blood bag for before a transfusion, which would mean it should not be adminisered?
1. Signs of tampering
2. Leaks
3. Discolouration
4. Clots
113
What are the 5 steps to administering the blood in for a blood transfusion?
1. Patient will require a cannula in situ
2. Attach giving set to blood bag, **run some blood through tubing to expel air**
3. once all air expelled, attach other end of the giving set to the cannula port
4. **set drip rate** to match amount of time you want to give the blood over
5. You and a colleague should document time and date the transfusion was started and sign to confirm all checks were carried out
114
What are the points at which baseline observations should be taken during a blood transfusion? The first three are **baseline**.
1. 0 mins
2. 15 mins
3. 30 mins
4. then on hourly basis
5. when transfusion is finished
115
What are the 4 groups of reactions that can occur following a blood transfusion?
1. Immediate - \<24 hours, immune
2. Immediate - \<24 hours, non-immune
3. Delayed - \>24 hours, immune
4. Delayed - \>24 hours, non-immune
116
What are 3 types of immediate (\<24 hours) immune reactions to a blood transfusion?
1. ABO incompatibility - Acute Haemolytic Transfusion Reaction
2. Transfusion-related acute lung injury (TRALI)
3. Anaphylaxis
117
What are 2 examples of immediate (\<24hour) non-immune transfusion reactions?
1. Bacterial infection
2. Fluid overload
118
What are 4 examples of delayed (\>24 hours) immune reactions?
1. Delayed haemolytic transfusion reaction (DHTR)
2. Febrile non-haemoytic transfusion reaction (FNHTR)
3. Post-transfusion purpura (PTP)
4. Graft vs host disease (GvHD)
119
What are 3 types of non-immune/infectious, delayed (\>24hr) transfusion reactions?
1. Viral
2. Malaria
3. Prions
120
What causes an acute haemolytic transfusion reaction (ABO incompatibility) following a blood transfusion?
121
Anti-A/B antibodies activate the complement pathway and the release of inflammatory cytokines
122
What are 4 early signs of acute haemolytic transfusion reaction?
1. Fever
2. Hypotension
3. Anxiety
4. Red-coloured urine
123
What are 2 late signs of acute haemolytic transfusion reaction?
1. Generalised bleeding (due to disseminated intravascular coagulation)
2. Hypotension
124
What causes transfusion-related acute lung injury (TRALI)?
Pathophysiology not fully understood but **antibodies** to **human** **neutrophils antigens** and **human leukocyte antigens (HLA)** have been implicated
125
What ist the typical presentation of TRALI?
sudden development of dyspnoea, severe hypoxaemia (O2 saturation \<90), hypotension, fever within 6 hours
126
How does TRALI usually resolve (transufsion-related acute lung injury)?
with supportive care within 48 to 96 hours
127
How can anaphylaxis occur in response to a blood transfusion?
Recipient is allergic to protein components in donor transfusion
128
What are 6 possible signs of anaphylaxis (following transfusion)?
1. Itchy rash
2. Throat or tongue swelling (angioedema)
3. Shortness of breath
4. Vomiting
5. Lightheadedness
6. Low blood pressure
129
What is the time frame of anaphylaxis following tranfusion?
Come on over minutes to hours, can result in death
130
How can blood transfusion lead to fluid overload, and what are 2 key risk factors?
* Each unit of blood is equivalent to 450ml of fluid, may cause overload if have **multiple transfusions**
* Most at risk as **elderly** and those with **congestive cardiac failure**
131
What causes a delayed haemolytic reaction to occur?
Antibodies to minor antigens such as rhesus or Kidd-
132
After what time period following transfusion doesdelayed haemolytic reaction occur and why?
between 3 and 14 days as a result of a secondary immune response
133
What are 4 signs of delayed haemolytic reaction to a blood transfusion?
1. Drop in haemoglobin level
2. Fever
3. Jaundice
4. Haemoglobinuria
134
What is febrile non-haemolytic transfusion reaction and what causes it?
Associated with fever but not directly with haemolysis, most commonly caused by antibodies directed against donor leukocytes and HLA antigens (unlike TRALI, in which donor plasma has antibodies directed against recipient HLA antigens mediating the lung damage - i.e. other way around)
135
What are 2 groups in which febrile non-haemolutic transfusion reactions mainly occur?
1. Multiply transfused patients
2. Women wtih multiple previous pregnancies
136
What is the difference in cause of TRALI (transfusion-related acute lung injury) and FNHTR (febrile non-haemolytic tranfsuion reaction)?
* TRALI is due to antibodies in the donor plasma against recipient HLA antigens (antibodies in **donor**)
* FNHTR is due to donor leukocytes and HLA antigens, and the recipient develops the antibodies against them (antibodies in **recipient**)
137
What is post-transfusion purpura?
* An adverse reaction to a blood transfusion or platelet transfusion that occurs when the body produces **alloantibodies** to the introduced **_platelets_' antigens.**
* Alloantibodies then detstroy patient's platelets leading to thrombocytopenia
138
What is the time frame of post-transfusion purpura occuring and how serious is it?
5-12 days after transfusion, potentially fatal condition
139
What is graft-vs host disease (GvHD)?
Medical complication following receipt of transplanted tissue frmo a genetically different person
140
What is the cause of graft vs. host disease?
immune cells (white blood cells) in the donated tissue (the graft) recognise the recipient (The host) as foreign. Transplanted immunecells then attack the host's body's cells
141
Why might Graft vs. host disease to occur following a blood transfusion?
If the blood products have not been irradiated or treated with an approved pathogen reduction system
142
When is a cryprecipitate transfusion used? 2 reasons.
1. Most often used for **hypofibrinogenemia**, most often due to massive haemorrhage/ transfusion or haemorrhage after cardiac surgery, or:
2. **Consumptive coagulopathy** e.g. neonates with specific clotting factor deficiecies
