Cost-benefit analysis of nitrous oxide in major surgery

1. Cost-benefit analysis of nitrous oxide in major surgery Presenter: Dr Alison Graham 2nd year Anaesthesia Advanced Trainee Co-Authors: Prof Paul S. Myles, Prof. Kate Leslie, Prof. Matthew T.V. Chan, Prof. Michael J. Paech, Dr Philip Peyton and Prof. Abdelazeem A. El. Dawlatly

2. Topics: • Review ENIGMA trial • Cost-benefit analysis • Methods • Results • Limitations • Conclusion

3. ENIGMA Trial • The Avoidance of Nitrous Oxide in Major Surgery • What are the consequences of using nitrous oxide? 80% O2 & 20% N2 • 30% O2 & 70% N2O VS

4. ENIGMA Results

5. ENIGMA Trial Results Kaplan-Meier estimates of discharge from the intensive care unit

6. ENIGMA Results

7. ENIGMA Results

8. Criticism of the ENIGMA Trial • “Despite the concerns regarding its adverse effects, nitrous oxide has actually had a central position in anesthetic practice primarily becauseit is inexpensive, widely available, and has a long-standing safety profile. The most obvious advantage of using nitrous oxide is that it allows a dose reduction of other anesthetic agents and opioids, which translates into less cardiovascular depression and significant cost reduction” Anesthesiology 2008; 108:541-2

9. Cost-Benefit Analysis of the ENIGMA Trial • What is the financial cost of using nitrous oxide?

10. Health economics

11. Health economics Health economics Cost Minimisation Cost benefit - $ only Cost effectiveness – natural units Cost utility - QALY

12. Cost-Benefit Analysis of the ENIGMA Trial • What is the financial cost of using nitrous oxide? • From the hospital administration’s point of view

13. Costs saved Maintenance anaesthetic Analgesia Vasopressors Expenses PONV prophylaxis PONV Infection/fever Pneumonia Atelectasis PACU ICU HLOS Cost-benefit N2O: variable costs

14. Costs saved Maintenance anaesthetic Analgesia Vasopressors Expenses PONV prophylaxis PONV Infection/fever Pneumonia Atelectasis PACU ICU HLOS Cost-benefit N2O: variable costs

15. Contributing Cost Estimates

16. Contributing Cost Estimates

17. ENIGMA Cost-Benefit Analysis: Results Estimated costs per patient (US dollars), Mean ± SD

18. ENIGMA Cost-Benefit Analysis: Sensitivity Analysis Estimated costs per patient (US dollars), Mean ± SD

19. Cost-Benefit Analysis Limitations • Estimated costs (but the statistics are real) • Hospital perspective only • Use of published estimates of costs • Precedent studies mostly from developed countries • No discrimination on methods • Variable costs only included • PACU costs controversial

20. Conclusions • There are significant additional costs with N2O use • No compelling argument to use N2O on the basis that it is an inexpensive drug

21. Questions

23. Sensitivity Analysis