Fig. 2
Patient-to-patient variability in minute ventilation (MV) in non-obese and obese orthopedic patients at different time-points in the perioperative course. Boxplots show MV mean and variance in (a) non-obese and (b) obese orthopedic patient cohorts at seven time-points pre-operatively, intra-operatively, and post-operatively. Dashed lines depict BSA-based MVPRED, as well as at-risk (80% MVPRED) and un-safe (40% MVPRED) ventilation thresholds. Post-operative MV variance is significantly greater in obese patients than in non-obese patients (p < 0.01), particularly in the PACU, and whereas the average MV at PACU discharge in the obese patients is significantly higher than in the non-obese patients, 10% of the obese patients spent >1/3 of the last half-hour in the PACU with un-safe MV