Post-op Surg & Fluids

Question 1

What can go wrong with fluid/electrolyte balance? [3]

Answer 1

1. Imbalance between input and output/losses
   
   • not able to eat/drink → drowsy/fasting/obstruction
   • medications → laxatives/diuretics
   • excess losses → diarrhoea/vomiting/polyuric/pyrexia)
2. Redistribution of fluid
3. Osmolar problems

Question 2

What is osmolarity and what is the normal serum osmolarity? [2]

Answer 2

1. a measure of the serum concentration of small diffusible ions, mainly Na, K, glucose and urea (sodium is most important)
2. normal = 280-300mOsm/kg

Question 3

What is the major clinical risk associated with osmolar problems? [1]

Answer 3

risk of cerebral oedema in acute hyponatraemia

Question 4

What are the aims of fluid management? [3]

Answer 4

1. Resuscitation
   
   • to restore circulation to vital organs following loss of intravascular volume
2. Routine Maintenance
   
   • patients not drinking/unable to drink/having to fast for over 8-12 hours should be started on IV maintenance fluid
3. Replacement
   
   • to treat any deficits or ongoing losses not needed urgently for resuscitation

Question 5

What are the 5 R’s in fluid prescription according to the NICE guidelines? [5]

Answer 5

1. Resuscitation
2. Routine maintenance
3. Replacement
4. Redistribution
5. Reassessment

Question 6

What are the types of intravenous fluid? [4]

Answer 6

1. Crystalloids
2. Saline (various, 0.9% is standard)
   
   • dextrose (various, 5% is standard)
     
     • goes into the intravascular, interstitial and intracellular space
   • “balanced solutions” (eg Hartmann’s or Ringer’s lactate)
     
     • goes into the intravascular and interstital spaces
   • sodium bicarbonate (1.26%) – expert advice only
3. Colloids
   
   • e.g. Gelofusion or starch-based fluid
   • goes into the intravascular space
4. Blood products
   
   • packed red cells
   • platelets or fresh frozen plasma (clotting factors)
   • human albumin solution

Question 7

Hypovolaemic shock:

1. what are the clinical signs? [6]
2. how do you resuscitate? [3]

Answer 7

1. Clinical signs:
   
   • Hypotension (systolic BP <100 mmHg)
   • Tachycardia (HR >90 bpm)
   • Peripherally cool
   • Capillary refill time >2 secs
   • NEWS >5
   • Passive leg raising suggests fluid responsiveness
2. Resuscitation:
   
   • fluid bolus
   • usually saline or Hartmann’s
3. always reassess