The Preoperative CardioPulmonary Variability Assessment (CPVA) will assess baseline HRV & RRV and the ability to tolerate mild physiologic stress. The assessment will involve a a Philips MP50 monitor that will collect continuous ECG (Lead II) and CO2-based respiratory waveform data with intermittent blood pressure (BP) measurements over a test of less than 60 minutes. We will measure the response to mild physiological stress which reflects adaptability, autonomic function and functional mobility by having the participant perform certain tasks such as sitting, standing, deep breathing, valsalva manoeuvres, and marching.

Implementing CPVA testing in thoracic surgery patients will be considered feasible if:

>50% of identified eligible patients are enrolled and consented, >90% of consented and enrolled patients complete CPVA testing protocol There is adequate data analysis from the CPVA in >90% of patients that complete the CPVA protocol >95% of CRFs are complete

The statistical association between preoperative HRV and RRV and major cardiac and pulmonary postoperative AEs will be determined by separating the patient's into subgroups based on (a) any AEs (any class), (b) serious AEs (Class III and above), (c) the type of AEs they experience (including POPCs, atrial fibrillation, air leak) and performing statistical analyses to determine if there is a significance between patients who experience AEs and those who don't based on the CPVA metrics.

A simple univariate logistic regression model will be created for each variability metric and literature-based thresholds will be used for the CPVA indices to assess their predictive power, which will be compared to that of the current predictor for the 3 types of AEs (POPC, arrhythmia, air leak). For each AE, a multiple logistic regression using the original predictors and variability features will also be performed to assess the added value of the variability features.