Post-Op Fluids

Question 1

You are the SHO on-call & have been called to surgical HDU to review a 60-year-old male who underwent anterior abdominoperineal resection under GA 12 hours ago. You didn’t attend operation & didn’t see him before. The nursing staff are concerned about his low UOP . Physical examination was unremarkable & the catheter was patent. Upon reviewing his fluids & observation charts , he is NPO & he received only 1L of fluid over the last 12 hours.

Q1: On the light of the fluids & observation charts, What’s the likely cause of low UOP?

Answer 1

1. Most likely due to dehydration

Question 2

Q2:What’s the appropriate management?

Answer 2

2. IV fluids – in hypotensive 20ml /kg/hr // normotensive 10ml/kg

Question 3

Q3: What’s the theoretical physiological rational for giving the fluid challenge rather than speeding the drip up?

Answer 3

3. As it’s diagnostic and therapeutic. As speeding up the drip will not resusitate the pt. according to Starling law –> increase in VR will vent.
   Stretch and contractility will increase and COP will improved

Question 4

Q4: The patient is monitored 2hourly, is that adequate?

Answer 4

4. No, should be monitored hourly

Question 5

Q5: Are there any reasons why synthetic colloids are not advised in post-op patient?

Answer 5

5. No evidence of benefits, more expensive, they may cause anaphylaxis and they increase mortality in septic pt.

Question 6

Q6: How are you going to manage this patient’s circulation for the remining of your shift?

Answer 6

6. Regular monitor of vital signs and crt and mental status. / I will do fluid challenge if necessary. / Maintain high index of suspicious for other sources of bleeding/ Contact my consultant and give clear instructions to nurse staff.

Question 7

Q7: If the patient becomes more haemodynamically unstable & you gave him more fluids. What means are available to more assess the CVS function & patient’s response to therapy?

Answer 7

• Minimally invasive cardiovascular monitoring (arterial line)
  – Lithium dilution cardiac output monitoring (LiDCO)
  – Pulse contour analysis (PiCCO)
• Transesophageal Doppler
• CVP monitoring (less frequently)

Question 8

Q8: Who to notify about this patient’s status ? When?

Answer 8

8. My consultant and ITU when o response to multiple fluid challenges

Question 9

Q9: What’re the hormones you expect them to be secreted in an attempt to preserve circulation volume?

Answer 9

9. Cortisol, ADH , aldosterone

Question 10

Q11: Where does ADH act?

Answer 10

11. CDs of kidney

Question 10

Q10: Where’s ADH produced & what factors stimulate its secretion?

Answer 10

10. produced in hypothalamus and stored in post pituitary. Fx; reducing circulatory voulme and plasma osmolarity increased and angiotensin ii.

Question 10

Q12: By what mechanism does ADH facilitate the reuptake of water from tubular fluid?

Answer 10

12. By stimulating the aquaporines which are water channels into the membranes of CDs which will transplant water to circulation

Question 11

Q13: Why does water cross from tubular fluid into tissue renal medulla?

Answer 11

13. High osmotic gradient btw medulla and tubules

Question 11

Q14: What’s the process by which the medullary tissue become hypertonic?

Answer 11

14. Counter current multiplier system explain it

Question 12

Q15: How does aldosterone act to maintain circulating volume?

Answer 12

15. Act on the receptors at the junction btw DCT and collecting ducts and reuptake Na and water

Question 13

Q16: How does angiotensin II act

Answer 13

16. Three main action; arteriolar VC raising Blood pressure, stimulate release of aldosterone, increase Na absorption and stimulate water intake