Prescribing IV fluids Flashcards
Total body water is approx what % of total body weight in males? What about in females?
60%
55%
Explain the 2/3 rule.
Flesh 24kg, water 46L
30L of that water is intracellular and the other 16L is extracellular.
11L if the extracellular water is interstitial and the other 5L is vascular.
Remember that fluid moves between compartments.
What 3 things can you prescribe to replace volume?
Crystalloids (water with varying degrees of salts)
Colloids (protein-rich and some salts in them as well)
Blood products
Crystalloids.
0.9% Saline 5% Dextrose 4%/0.18% dextrose/saline Ringer’s Lactate Solution Hartmann’s Solution (Propriotary infusion solutions) 0.45% Saline
Which crystalloids can you not add/change K+?
Why?
Ringer’s Lactate Solution
Hartmann’s Solution
(Propriotary infusion solutions)
As they contain K+ already.
Why are colloids preferable to crystalloids?
Colloids stay in vascular compartment better than crystalloids due to containing protein.
What does 0.9% and 0.45% Saline contain?
Na+, Cl-
What does 5% Dextrose contain?
Glucose
What does 4%/0.18% dextrose/saline contain?
Na+, Cl-, Glucose
What do Ringer’s Lactate Solution and Hartmann’s Solution contain?
Na+, K+, Ca2+, Cl-, lactate
Normal plasma range of Na+
137-144
Normal plasma range of K+
3.5-4.9
Normal plasma range of Ca2+
2.2-2.6
Normal plasma range of Cl-
95-107
Normal plasma range of lactate
0.3-1.3
Which crystalloids change both ECF and ICF?
All apart from 0.9% saline
Which crystalloids change only ECF?
0.9% saline
Which crystalloids change mainly ECF (about 90%)?
Ringer’s lactate and Hartmann’s
How can normal saline cause hyperchloraemic acidosis?
NaCl + H20 ↔ HCl + NaOH The HCl and NaOH should cancel Due to difference in composition of 0.9% saline and plasma, [Cl-] rises significantly (relative to [Na+]) and this tips the acid-base balance toward HCl, thus metabolic acidosis.
What is K+ available as?
Available as 20mmol/L or 40mmol/L, in:
• 0.9% Saline
• 0.18% Saline + 4% dextrose
• 5% dextrose
What is the fastest rate of K+?
Not to be given more than 20mmol/hr
Give three examples of colloids.
Gelofusine, Volplex, Haemaccel
What are colloids?
Contain high molecular weight proteins and electrolytes
Why are colloids not commonly used anymore?
• Some trial in sepsis suggests inferior
• ?Used in volume resuscitation
• NICE guidance moves it down the choices
• Small risk of allergic / anaphylactoid reactions /
anaphylaxis
What is the elimination of colloids?
Elimination t1/2 in blood ranges 4-8 hrs
Give some signs that a patient is volume depleted/dry.
(Reduced capillary refill) Tachycardic Hypotension (+ Postural) Low / absent JVP Decreased skin turgor Dry mucosae Oliguria (Decrease) Daily Weight Chart
Give some signs that a patient is volume overloaded/wet.
(Occ tachycardic) Raised JVP Pulmonary oedema Pleural effusions Ascites Peripheral oedema (Increase) Daily Weight Chart
Possible indicators for fluid resuscitation.
- SBP <100 mmHg, HR >90, Cap refill >2sec, RR >20/min
- NEWS ≥5
- Cool peripheries
- 45o passive leg raise test +ve
- Fluid balance charts and weight charts
- Trends in FBC, U&Es
What is used for fluid resuscitation?
Use crystalloids that contain
– Sodium in the range 130–154 mmol/l
– Bolus of 500 ml over less than 15 minutes
• Do not use tetrastarch for resuscitation, unless
as part of a clinical trial
• Consider human albumin solution 4–5% only
for resuscitation in patients with severe sepsis
For routine maintenance alone, restrict the initial
prescription to…?
25–30 ml/kg/day of water and ~ 1 mmol/kg/day of K
+, Na+, Cl–, ~ 50–100 g/day of glucose to limit starvation ketosis.
How should maintenance fluids be changed for obese patients?
Adjust the IV fluid prescription to their ideal body weight. Use lower range volumes per kg. Rarely need more than a total of 3 litres/day. Seek expert help if their BMI >40.
Do not exceed…for routine fluid maintenance.
30 ml/kg/day
Consider prescribing less fluid (for example, 25 ml/kg/day fluid) for patients who…
Are older or frail, or have renal impairment or cardiac failure
When prescribing for routine maintenance alone, consider using…
25–30 ml/kg/day sodium chloride 0.18% in 4%
glucose with 27 mmol/l potassium on day 1.
Prescribing more than 2.5 litres per day increases the
risk of…
Hyponatraemia
How do you calculate how long to give the fluid over?
Calculate time course based on volume required and “speed”
How is fluid better prescribed (rather than a unit of time)?
Better prescribed as a “rate” (e.g. ml/hr) with volumetric pumps
Cannula size 22 G
What is the colour and how long does it take to infuse 1L?
Blue
22 mins
Cannula size 20 G
What is the colour and how long does it take to infuse 1L?
Pink
15 mins
Cannula size 18 G
What is the colour and how long does it take to infuse 1L?
Green
10 mins
Cannula size 16 G
What is the colour and how long does it take to infuse 1L?
Grey
6 mins
Cannula size 14 G
What is the colour and how long does it take to infuse 1L?
Red
3.5 mins
All patients continuing to receive IV fluids need regular monitoring.
This should initially include at least daily
reassessments of…
– clinical fluid status
– U&Es
– fluid balance charts
– weight measurement twice weekly
Monitoring of urine sodium can help to…
– to identify whole-body sodium depletion in patients
who have high-volume gastrointestinal losses
– in assessing sodium status in oedematous patients
Monitoring requirements if receiving IV fluids containing chloride concentrations greater than 120 mmol/l.
Monitor their serum chloride concentration daily (!).
Input
- Oral
- NG / PEG / JEJ
- IV
- Includes flushes and TPN!
Output
• Urine
• Stools - diarrhoea / stomas and fistulas
• Drains - chest, ascitic, abdominal, percutaneous, wounds, NG
• Insensible losses (~0.5L/day) - accelerated in burns,
tracheostomy, fever
How often to prescribe?
If patient unwell, prescribe over shorter durations with regular re-assessments
If patient is well and stable, consider prescribing over longer durations
Risks of IV therapy. (6)
Fluid overload Electrolyte imbalance Infection Phlebitis / thrombophlebitis Infiltration / extravasation Colloids – additional small risk (1/10000) of allergic/anaphylactoid reactions/anaphylaxis
How to prescribe?
Date/Time Type of fluid Volume Drug added (and dose) Infusion rate Route Signature and Bleep Update nursing team!
Blood transfusion indications. (5)
Consider transfusion if:
• Massive / ongoing haemorrhage
• Hb < 8 (but debatable), or
• Hb 8 - 10 and symptomatic, or cardiac, respiratory, cerebrovascular disease
Risk of blood transfusions.
Immune reactions - acute haemolytic reaction, febrile non-haemolytic transfusion reaction, delayed haemolytic reaction, anaphylaxis, transfusion associated acute lung injury (TRALI)
Infections - Bacterial, viral, ?prion disease
Volume
Electrolytes - hyperkalaemia, hypocalcaemia, worsening coagulopathy (massive transfusions), iron excess (long-term)
CMV -ve blood is indicated for… (4)
CMV -ve recipients of allogeneic stem cell and bone marrow transplants
CMV -ve pregnant women
Intrauterine transfusions
Infants weighing less than 1200 g at birth
CMV -ve blood may be recommended for…(4)
CMV -ve individuals with: • HIV infection • Conditions likely to require allogeneic hematopietic stem cell transplant • Solid organ transplant recipients • Severe neutropenia
Irradiated blood indicated for…
- Allogeneic haemopoetic stem cell transplant recipients
- Autologous stem cell transplantation recipients
- Hodgkin lymphoma
- Aplastic anaemia
- After purine analogues / antagonists / anti-CD52
Irradiated blood unnecessary for…
Routine surgery, solid tumours, HIV infection, autoimmune diseases or after solid organ transplantation
Blood transfusion and furosemide - common practice?
20 – 40 mg IV with every second unit transfused
Especially in elderly, known heart failure.
Blood transfusion and furosemide - caution if?
Active bleed, large volume deficit, electrolyte imbalance
Called to see patient as emergency • A – Patent • B – Sats 97% OA, chest clear • C – BP 68/45, PR 124, HS 1+2+0, JVP ↓ • D – GCS 14/15 (E4/V4/M6), BM 8 • E – No clear source of bleed
GIVE FLUID RESUSCITATION
50M, young stroke
• Unsafe swallow - kept NBM
• No other past medical history, no drug history
• Clinically euvolaemic, normal U+Es
GIVE MAINTENANCE FLUIDS Consider Hartmann’s, Lactate’s etc. – 1 “salt” + 2 “sweet” over one day – 1 x 1L 0.9% sodium chloride – 2 x 1L 5% dextrose – 8hrly – Potassium replacement guided by plasma levels but if normal - replace with daily requirements (60mmol)
