Cardiopulmonary exercise testing as a predictor of peri-operative morbidity and length of stay following major surgery
Author(s):	Pachter D., Turner H., Chuter E.
Institute(s):	Sunderland Royal Hospital, Dept of Anaesthesiology, Sunderland, United Kingdom
Text:	Background and Goal of Study: Cardiopulmonary exercise testing (CPET) is a reliable and objective test for evaluation of functional capacity. It is widely used as part of pre-operative assessment prior to major surgery.
We looked at the effect of CPET performance data on length of hospital stay and incidence of post operative complications in patients undergoing major surgery in our hospital.
Materials and methods: Retrospective analysis was performed of all patients who underwent CPET testing, and thereafter proceeded to surgery, following the introduction of the service in November 2014.
Previous studies have reported that AT < 11ml/kg/min and VE/VCO2 > 34ml/kg/min are predictors of worse post-operative outcome.1 We therefore sub-divided our patients into groups with CPET parameters better or worse than these cut off points, and looked at the influence on length of stay and incidence of complications.
Results and discussion: 70 patients underwent CPET testing, 32 of whom proceeded to surgery. 22 underwent vascular surgery (14 EVAR, 8 open AAA repair). 10 underwent major urological or colorectal procedures.
Mean length of stay (LOS) in patients with AT>11 was 6.8 days compared to 9.6 days in those with AT < 11 ( Student t test p=0.084). In patients with VE/VCO2< 34, mean LOS was 8.8 days, compared to 7.5 days in those with VE/VCO2>34 (p=0.485). 
In patients undergoing EVAR, mean LOS was 3.1 days in patients with AT>11, vs 6.6 days if AT< 11 (p=0.019). Those with VE/VCO2>34 had a mean LOS was 5.3 days vs 3.2 days if VE/VCO2 < 34 (p=0.115). 
For more invasive surgery (open AAA repair/ major colorectal and urology), mean LOS in patients with AT>11 was 9.2 days vs 12.5 days in patients with AT< 11 (p=0.122). In this group, patients with VE/VCO2 >34 has a mean LOS of 9.2 days vs 11.4 days if VE/VCO2 < 34 (p=0.21).
Post-operative complication rates were higher in patients with AT< 11 (6/9, 66.7%) than those with AT> 11 (11/23, 43.5%), and in patients with VE/VCO2 >34 (12/21, 57.1%) than those with VE/VCO2 < 34 (4/11, 36.3%). (Fisher exact test p=0.003).
Conclusions: Reduced AT was associated with an increase in length of hospital stay, significantly so in patients undergoing EVAR . Reduced AT and impaired VE/VCO2 were associated with a significantly increased risk of post operative complications.
References: 
1 Wilson R et al. Impaired functional capacity is associated with all cause mortality after major elective intra-abdominal surgery. Br. J. Anaesth. (2010) 105 (3):297-303