1. Mannitol and current trends in fluid management
Eanan Harkin
Royal Hospital, Belfast

2. Contents What is Mannitol? Use on CPB ARF The Study Rationale Aims
Methodology
Results
The Survey
Questions
Discussion
Conclusion
Contents

3. 1,2,3,4,5,6-hexanehexol (C6H8(OH)6), is a polyol (sugar alcohol)
A naturally occurring substance found in marine algae, fresh mushrooms, and in the exudates from trees.
Solutions are acidic ( pH 6.3), proprietary preparations have sodium bicarbonate added for pH adjustment, may crystallize if stored at room temperature but can be made soluble again by warming.
What is Mannitol?

4. Use in Cardio-pulmonary Bypass
Low molecular weight (182) so freely filtered through renal tubules. Not reabsorbed, continues to be osmotically active in the tubules and therefore is an osmotic diuretic.
Releases renal prostaglandins leading to renal vasodilation and increase in tubular urine flow. Believed to protect against renal injury by reducing tubular obstruction.
Free-radical scavenger; reduces the harmful effects of ischaemia– reperfusion injury
Use in Cardio-pulmonary Bypass

5. Acute Renal Failure (ARF)
Acute Renal Failure in 5%. (10-20% mortality) Especially if CPB over 3 hours
Dialysis in 1-2% (50-60% mortality)
Increased LOS and higher costs
Combination of causes: ↓ C.O. hypovolaemia, emboli, polypharmacy, reperfusion, CPB; complement/free radicals/cytokines.
Reported to be used by ≈ 33% UK Cardiac centres
Recent Anaesthesia articles suggests no difference in ARF incidence in patients with normal pre-op creatinine
Acute Renal Failure (ARF)

6. Rationale Anaesthesia 2008: 50 low risk Cardiac Patients selected
25 patients randomised into each group Mannitol/no Mannitol
Standardised Cardiac anaesthetic and bypass run performed.
No difference in plasma creatinine, U.O. fluid balance or rates of renal failure
Rationale

7. Prospective Observational Study to evaluate the relevance of mannitol in CPB prime for low risk patients undergoing cardiac surgery:
Inclusion Criteria:
1. Single procedure; AVR, MVR, CABG, ASD
2. eGFR > 50
3. CPB < 120 min
Exclusion Criteria:
1. In-patients
2. Emergency surgery
Aims

8. Patients were grouped as per the inclusion criteria
Patients were grouped as per the inclusion criteria. Decision for the use of the mannitol was made according to current routine practice.
Primary Outcomes
Additional fluid on bypass
Use of Vasopressors
Fluid Balance (Intra-op, Day 1 and 2)
Renal Status (Pre-op, Day 1, 2 and 5)
Use of CRRT
Need for transfusion
Secondary Outcomes
Duration of Ventilation
Length of Stay
Methodology

9. Patient Characteristics
Mannitol (n=17)
No Mannitol (n=21)
AGE (years)
Mean (SD)
66 (9.62)
69 (10.94)
MEAN WEIGHT (kg) 78 84
M/F
14/3
14/7
HTN 12 14
DIABETES 6 7
COAD 4
EUROSCORE
1.12
Patient Characteristics

10. Intra-op Data

11. Fluid Balance

12. Renal Function

13. Secondary Outcomes

14. Furthermore
Approximately 15% of patients (in both groups) developed a decreased level of kidney function throughout the first 5 days of recovery.
No patients required CRRT.
Approximately 30% of patients required transfusion.
Limitations:
Small Study sample.
Not uniform anaesthetic.
eGfr not an accurate enough measure of kidney function.

15. Fluid Management Survey
What is the main constituent of your CPB prime?
What is your average prime volume?
What other additives are included in your prime?
On bypass, what is your fluid replacement of choice?
What is your target (optimal) Hb?
What is your general transfusion trigger on CPB?
Fluid Management Survey

16. Survey Survey was sent to 53 units in the UK and Ireland.
There were 32 satisfactory replies (response rate of 60%).
Several paediatric unit responses were excluded.
Survey

17. Prime Fluids

18. Prime Volume

19. Additives

20. Replacement Fluids

21. Transfusion Triggers Lowest transfusion trigger given as 65g/L.
Majority of centres transfuse at 70-75g/L.
Anything above the trigger will be tolerated as long as DO2, etc are satisfactory.
Transfusion Triggers

22. Thank you!
And it’s over…