I often allow my patients to breath spontaneously when I'm using LMAs. Since I'm heavy handed with the narcs, I usually target a RR around 8 (with a nice narcotic pattern). As a result I often run cases with an ETCOs in the low 60s. However, I know some providers feel that it is both bad form and dangerous to "induce acidosis" in patients.

For a healthy patient with stable VSS, how high will you let the CO2 rise before you support ventilation and what factors affect your decision?