Is there a correlation between lung function values and cardiopulmonary exercise outcome?

Abstract

BackgroundCardiopulmonary exercise testing (CPET) has become an important tool for perioperative assessment because it may identify patients at risk of postoperative cardiopulmonary complications. An anaerobic threshold (AT) less than 11 mL/min/kg has been recommended as a way to stratify postoperative treatment in colorectal surgery patients. The British Thoracic Society guidelines recommend that a peak VO2 (pVO2) less than 15mL/min/kg confers high risk in thoracic surgical patients. Because CPET can be challenging to carry out, this study aimed to determine whether lung function values correlated with CPET outcome and therefore could be used as an alternative measure. Methods500 pre-operative colorectal (388) and oesophageal (112) patients were analysed. Gas transfer and spirometry were performed to assess lung function. CPET was performed on a cycle ergometer to calculate pVO2 and AT. The predictive capacity of forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), transfer factor of the lung for carbon monoxide (TLco), and carbon monoxide transfer coefficient (Kco) values compared with pVO2 and AT was assessed using receiver operating characteristic (ROC) curves. FindingsThe area under the curve (AUC) for pVO2 and AT for FEV1 was 0·56 and 0·55, respectively; for FVC 0·56 and 0·57; for TLco 0·72 and 0·64, and for Kco 0·63 and 0·56. There was a significant correlation between AT and pVO2 (AUC 0·89); an AT greater than 12 mL/min/kg predicted pVO2 greater than 15 mL/min/kg (sensitivity 77·3%, 1–specificity 13·7%). InterpretationLung function variables cannot reliably predict pVO2 or AT outcome. However, of the variables recorded, TLco was the best marker for predicting a pVO2 greater than 15 mL/min/kg. In preoperative assessment of patients undergoing thoracic surgery, an AT of more than 12 mL/min/kg could be used as an alternative to CPET if the patient is unable to achieve a pVO2 greater than 15 mL/min/kg. FundingKing's College London.