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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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”

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

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?

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.

Staehr, A. K. , Meyhoff, C. S. , & Rasmussen, L. S. (2011) 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