Abstracts and Programme: EUROANAESTHESIA 2011: The European Anaesthesiology Congress: Monitoring: Equipment and Computers
Exploring the “two flights of stairs” rule with a novel step-oximetry device: Comparison with cycle ergometry exercise testing
Background and Goal of Study: Patients undergoing pre-operative evaluation who are able to climb two flights of stairs are traditionally considered to possess sufficient physiological reserves to undergo major surgery with a reduced rate of peri-operative complications. In thoracic surgery peak oxygen uptake (VO2) < 10ml/kg/min predicts poor outcome while peak VO2>15 ml/kg/min correlates with good outcome. It is not known whether there is a good correlation between step climbing ability and peak VO2.
Materials and Methods: Seventy four subjects were recruited during routine attendance for cycle-ergometry cardiopulmonary exercise testing (CPET) in our pulmonary diseases institution. Following their CPET, patients rested for ˜30 minutes and then performed a step-oximetry test. In this test they step on and off the step sensor until maximal exertion. The step sensor is a 17cm high ‘aerobic’ step, adapted with pressure sensors able to transmit a signal to the computer when the subject mounts the step with both feet. A pulse oximeter supplies data on heart rate and SpO2. These integrated signals are then analyzed. Patients were allocated to two groups, according to whether or not they were able to climb 40 steps (approximately two flights or 6.8m).
Results and Discussion: Results are presented in table 1. Patients able to climb 40 steps had higher peak VO2 than those unable to do so (15.1 ml/kg/min and 10.8 ml/kg/min respectively, p< 0.0001). They also used higher percentage of their cardiac reserves during exercise (79 % and 67% respectively, p< 0.00001).
Conclusion(s): Patients unable to climb 40 steps have significantly lower exercise capacity during CPET. Mean values for VO2 in the two groups match well with known cut-off values for evaluating risk in patients undergoing thoracic surgery. Step oximetry is a promising novel technique of objectively and easily assessing patients' exercise capacity in the pre-operative clinic.© 2011 European Society of Anaesthesiology