O 2 vs N 2 O . Who ’ s the bad guy??

1. O2 vs N2O. Who’s the bad guy?? Yee l. kwan, rn, ccrn Dunap, class of 2013 October 22, 2012

2. How many of you… • Yes • No Always use 100% O2 for emergence?

3. I routinely… • Yes • No Titrate the FIO2 to the lowest amount my patient needs to maintain their baseline sat.

4. What’s the point? • By the end of this presentation you should be able to……. • Discuss the pros & cons of O2 and N2O use • Identify risks for and s/s of O2 toxicity • Discuss various methods/techniques to prevent atelectasis in our pts

5. o2 is good b/c • Well, it’s essential to life! • Possible prevention of surgical site infection (SSI) • Can reduce incidence of PONV • Prevention of hypoxia

6. Meyhoff, C.S., Staehr, A. K., & Rasmussen L. S. (2012)

7. Hazards of o2 therapy • Oxygen toxicity • Absorption atelectasis* • Induced hypoventilation • Fire hazard • Retinopathy of Prematurity (ROP)

8. Atelectasis….did you know? • In 90% of anesthetized pts • Both with spontaneous ventilation and paralysis • Edmark et al. – CT of lungs of anesthetized patients • PEEP – 10 cmH2O • VC maneuver – 40 cmH2O, 7-8s • Benoit et al. – postop atelectasis

9. Atelectasis….did you know? Benoit et al. (2002)

10. I typically…. • Yes • No • Depends on who I’m working with that day Use N2O regularly as part of my anesthetic (assuming no contraindications).

11. I don’t use N2O because….. • I’m not comfortable with it • I prefer to keep things simple • Risk of N&V • My preceptors don’t like it

12. N20 is good b/c • Has analgesic effects • Rapid uptake and elimination • Little cardiac or respiratory depression • Nonpungent • Additive effect with co-administration of other volatile agents • Can speed up the rate of lung collapse for OLV

13. 2nd gas effect…in reverse • Using the 2nd gas effect to speed up emergence • Peyton et al. found • Time to eye opening and extubation were significantly shorter • Partial pressure of Sevo 39% higher

14. N20 Contraindications Absolute relative Pulmonary HTN Prolonged anesthesia >6hrs 1st trimester High risk PONV Risk of MI • Known deficiency of enzyme or substrate in methionine synthase pathway • Gas filled spaces • Increased ICP

15. Do you use recruitment maneuvers during your anesthetics? • Yes • Not usually • No

16. When I use a recruitment maneuver I apply pressure to • 20cmH2O • 30cmH2O • 40cmH2O • I don’t know. I just squeeze until it feels “about right”

17. After this presentation I will definitely think about using N2O on my next patient • Yes • No

18. In summary….. • Lots of evidence already exists both pro and con • Every patient requires individual consideration • There never is a right or wrong choice • Think about why you do what you do – is there a good rationale?

19. References: Edmark, L., Kostova-Aherdan, K., Enlund, M., & Hedenstierna, G. (2003). Optimal oxygen concentration during induction of general anesthesia. [Clinical Trial Randomized Controlled Trial]. Anesthesiology, 98(1), 28-33. Edmark, L., Auner, U., Enlund, M., Ostberg, E., & Hedenstierna, G. (2011). Oxygen concentration and characteristics of progressive atelectasis formation during anaesthesia. [Research Support, Non-U.S. Gov't]. Acta anaesthesiologica Scandinavica, 55(1), 75-81. doi: 10.1111/j.1399-6576.2010.02334.x Grocott, H. P. (2008). Oxygen toxicity during one-lung ventilation: is it time to re-evaluate our practice? [Review]. Anesthesiology clinics, 26(2), 273-280, v. doi: 10.1016/j.anclin.2008.01.008 Hedenstierna, G., & Edmark, L. (2010). Mechanisms of atelectasis in the perioperative period. [Research Support, Non-U.S. Gov't Review]. Best practice & research. Clinical anaesthesiology, 24(2), 157-169. Hedenstierna, G., & Rothen, H. U. (2000). Atelectasis formation during anesthesia: causes and measures to prevent it. [Review]. Journal of clinical monitoring and computing, 16(5-6), 329-335. Meyhoff, C. S., Jorgensen, L. N., Wetterslev, J., Christensen, K. B., & Rasmussen, L. S. (2012). Increased Long-Term Mortality After a High Perioperative Inspiratory Oxygen Fraction During Abdominal Surgery: Follow-Up of a Randomized Clinical Trial. Anesthesia and analgesia. doi: 10.1213/ANE.0b013e3182652a51 Rothen, H. U., Sporre, B., Engberg, G., Wegenius, G., Hogman, M., & Hedenstierna, G. (1995). Influence of gas composition on recurrence of atelectasis after a reexpansion maneuver during general anesthesia. [Clinical Trial Comparative Study Randomized Controlled Trial Research Support, Non-U.S. Gov't]. Anesthesiology, 82(4), 832-842.

20. Staehr, A. K., Meyhoff, C. S., & Rasmussen, L. S. (2011). Inspiratory oxygen fraction and postoperative complications in obese patients: a subgroup analysis of the PROXI trial. [Comparative Study Multicenter Study Randomized Controlled Trial Research Support, Non-U.S. Gov't]. Anesthesiology, 114(6), 1313-1319. doi: 10.1097/ALN.0b013e31821bdb82 Vimlati, L., Kawati, R., Hedenstierna, G., Larsson, A., & Lichtwarck-Aschoff, M. (2011). Spontaneous breathing improves shunt fraction and oxygenation in comparison with controlled ventilation at a similar amount of lung collapse. [Comparative Study Research Support, Non-U.S. Gov't]. Anesthesia and analgesia, 113(5), 1089-1095. doi: 10.1213/ANE.0b013e31822ceef8