|
|
Stair climbing test as a predictor of cardiopulmonary complications after pulmonary lobectomy in the elderly.Brunelli A, Monteverde M, Al Refai M, Fianchini A. Ann Thorac Surg 2004;77:266-270.Reviewer: A. Maslow, MD
Introduction:The authors sought to evaluate the use of exercise tests for risk assessment prior to elective thoracotomy and lung resection for non-small cell lung cancer (NSCLC) in elderly patients (>70 years). Exercise testing was compared to other preoperative cardiopulmonary function tests to determine "operability". Methods:One hundred and twenty seven patients were scheduled for pulmonary lobectomy between 2000 and 2003. 'Operability' was assessed using a number of preoperative tests and measurements including blood gas analysis, electrocardiography, echocardiography, pulmonary function tests, and stair climbing. More invasive assessments (e.g. cardiac catheterization) were performed individually as needed. Pulmonary function testing included forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), FEV1/FVC ratio, and carbon monoxide diffusion lung capacity (DLCO). Calculated values included predicted postoperative FEV1 (ppoFEV1; (preop FEV1/number of functioning lung segments) x number of functioning segments after surgery)), and predictive postoperative DLCO (ppoDLCO; (preop DLCO/number of functioning lung segments) x number of functioning segments after surgery)). The number of functioning segments was estimated by computed tomography scan, and bronchoscopic evaluation. Tests were performed prior to and after bronchodilator therapy. Stair climbing was performed on stairs with a stair height of 0.155 meters/stair, with each flight containing 11 stairs. Patients paced themselves and climbed the maximum number of stairs until dyspnea, chest pain, and/or exhaustion was noted or reported. Oxygen consumption was calculated (not directly measured). Work was measured by the product of height of each step x steps climbed per minute x weight (kg). Maximum oxygen consumption (VO2 max; ccO2/min) was calculated by (5.8 x weight (kg)) + 151 + (10.1 x work)). Predicted postoperative VO2 max (ppoVO2 max) was also calculated in similar fashion as other predicted postoperative measures. Assessment of cardiac morbidity included the patient's cardiac history and measures of maximal heart rate achieved with comparison to predicted maximal heart rate for age (220 - age). Other data included a variety of patient demographics and details of the surgical procedure. Postoperative cardiopulmonary complications were recorded as those occurring within 30 days of surgery. Results:One hundred and nine patients who performed the stair climbing underwent surgery. Twenty-nine of (26.6%) patients had cardiopulmonary complications and 3 (2.7%) died. Complications included pneumonia (12), arrhythmia (12), respiratory failure (2), pulmonary edema (2), myocardial infarction (1), and cardiac failure (1). Of eighteen additional patients who were not able to perform stair climbing due to limited physical ability, seven (38.9%) had significant morbidity, of which 4 (22.2%) died. Univariate analysis demonstrated a lower FEV1 (79.6% vs. 87.3%), FVC (90.2% vs. 97.3%), ppoFEV1 (63.2% vs. 70.0%), and stair height climbed (16.23 m vs. 19.61 m) were associated with significant morbidity. Stepwise logistic regression analysis showed that preoperative cardiac morbidity and stair height climbed remained significantly associated with postoperative cardiopulmonary morbidity. Calculated oxygen consumption was not a significant predictor of morbidity. Additional analysis showed that 17 of 82 patients (20.7%) who climbed >1.4 meters, and 4 of 7 (57.1%) patients who climbed < 1.2 meters had complications. Eight of 20 patients (40%) who climbed between 1.2 and 1.4 meters had postoperative complications. Eight patients with prohibitive preoperative assessments of ppoFEV1 and ppoDLCO (< 40%) underwent surgical resection based on climbing > 1.4 meters (VO2 max > 20 ml/min/kg and ppoVO2 max > 15 ml/min/kg). Four had significant complications and no deaths were reported. Discussion:The authors conclude that 'symptom-limited' stair climbing test is predictive of outcome after thoracotomy and lung resection for elderly patients. Furthermore, surgery may be safely performed based on adequate stair climbing regardless of criteria based on pulmonary function testing. Comment:This study demonstrates and adds additional support for the predictability of functional capacity on perioperative outcome. The authors had previously reported similar results in younger patients.2 These data report a stepwise increase in morbidity with decreasing functional capacity. The manuscript also describes a number of cases in which preoperative pulmonary function tests may have been less predictive of outcome compared to assessment of functional capacity. These conclusions are consistent for both thoracic and non-thoracic surgical patients, demonstrating that outcome is related to the functional capacity of the patient.3,4,5 Other investigations have demonstrated that a VO2 max > 20 cc/kg/min were associated with a good outcome for patients undergoing thoracotomy and lung resection.3,4,5 These data also demonstrate greater morbidity with decreasing VO2 max (> 20cc/kg/min; 15-20 cc/kg/min; and < 15 cc/kg/min).3,4,5 Although Bruneli et al did not demonstrate an association between VO2 max and outcome, oxygen consumption was not directly measured, and may be less accurate. However, for eight patients with prohibitive pulmonary function tests who successfully underwent surgery based on their functional capacity, the preoperative VO2 max was > 20 ml/kg/min. Good outcome has been previously reported for non-cardiac thoracic patients with reduced preoperative FEV1 (<60%) who recorded a VO2 max > 15 ml/kg/min.(5) Previously reported data have demonstrated good outcome for surgical and non-surgical patients who can manage > 5 metabolic equivalents (1 MET = VO2 3.5 ml/kg/min; > 5 MET = VO2 > 15 to 18 ml/kg/min).6,7 Previous guidelines have suggested that functional capacities > 4 METs are predictive of lower risk for perioperative complications.8 However, this was applied to a wide range of surgeries including lower surgical risk procedures than thoracotomies. Other data have reported an intermediate range between 5 and 10 METs to be associated with good outcome. A functional capacity > 10 METs is associated with excellent outcome regardless of the presence of CAD, and below 5 METs is associated with poor outcome.1,2,3,4,5,6,7 Oxygen consumption > 20 cc/kg/min is approximately equal to 7 METs which may be similar to carrying heavy (>/= 80 lbs) loads, snow shoveling, heavy household work, and a number of sporting activities (doubles tennis, dancing, skiing, jogging or walking 5 miles per hour (9 METs).8,9,10,11 These data stress the importance of individual patient interview and assessment. While preoperative testing is useful, it should be applied to, as a part of the clinical assessment of the patient. Statements or questions such as "The patient looks better than the data would suggest" or "Does the patient pass the look-test?" remain valid. References
Table of Contents:
© Society of Cardiovascular Anesthesiologists Questions or comments? Please send email to webmaster@scahq.org |