Introduction Cardiopulmonary exercise testing (CPET) is used to identify physiological limitation to exercise and aid diagnosis of cardiorespiratory, psychological and muscle disorders.1 It is also frequently used to stratify operative risk thereby aiding decision making in patients considered for major surgical procedures.2
The evidence for risk stratification is based on the oxygen consumption at anaerobic threshold (VO2 AT) along with metabolic equivalence.2 Attention is therefore generally paid to the numerical value of these measures rather than full interpretation of the data. Further interpretation may allow further diagnosis and optimisation of pre-existing conditions.
Methods We retrospectively applied a simple diagnostic algorithm (Figure 1) to CPETs undertaken by patients considered for major surgery in the Victoria Infirmary, Glasgow between 2014–2016.
Results The records of 39 patients who had a pre-operative CPET testing were analysed: 22 male, 17 female, age range 43–88, median 73.A total of 26 patients were classified as high risk, 23 achieved an AT <11 mls/kg/min and 3 with a metabolic equivalent <4.0mls02/kg/min. Both parameters were low in 13 patients. Ten patients had their procedures cancelled due to this. Eleven high risk patients had a normal VO2 max.
Upon applying the diagnostic algorithm; 15 patients were deconditioned, 6 had cardiovascular limitation, 3 had respiratory limitation and 15 were normal.
In the ‘high risk’ population: 2 patients had respiratory limitation with pre-existing respiratory conditions and were cancelled. Six patients had cardiovascular limitation with 3 patients having pre-existing cardiac diagnosis, 3 were cancelled. Seven of the patients were ‘deconditioned’; 5 were cancelled as a result.
Conclusion This algorithm suggests that 8 patients were considered high risk as a result of cardiorespiratory disease and a further 7 as a result of deconditioning. Appropriate speciality review and intervention or an exercise prescription pre-operatively might allow patients to improve their operative risk and therefore to proceed to major surgery.
Cooper C, Storer T. Exercise testing and interpretation. A practical approach. Edinburgh: Cambridge University Press, 2001.
Moran J, et al. Role of cardiopulmonary exercise testing as a risk-assessment method in patients undergoing intra-abdominal surgery: a systematic review. BJA 2016;116(2):177–191.