Pulmonary Function Testing

Preoperative Pulmonary Function Evaluation in Lung Resection Ri 李佩蓉/王奐之 CR 顏郁軒 Pulmonary Function Test • Preoperative pulmonary evaluation of patients with lung cancer concerns both resectability and operability. – resectability: TNM staging – operability: how much tissue can be safely removed Commonly Used Parameters • FEV1 (Forced Expiratory Volume in 1 second) – FVC (Functional Vital Capacity) – FEV1/FVC • MVV (Maximum Voluntary Ventilation) = MBC (Maximum Breathing Capacity) • DLCO (Diffusing Capacity of Carbon Monoxide) • VO2 max (Maximum Oxygen Consumption) FEV1 • best parameter to predict risk of post-op complications (including death) • ppoFEV1 (predicted postoperative FEV1) Am J of Med (2005) 118, 578–583 Chest (2003) 123, 2096-2103 Resp Med (2004) 98, 598-605 MVV (MBC) • largest volume breathed voluntarily in 1 min • an estimate of the peak ventilation available to meet physiological demands • represents respiratory muscle strength and correlates with post-op morbidity Am J of Med (2005) 118, 578–583 Chest (2003) 123, 2096-2103 Resp Med (2004) 98, 598-605 DLCO • independent predictor for risk of post-op complications (including death) • reflects alveolar membrane integrity and pulmonary capillary blood flow • low DLCO implies significant emphysema, and reduced pulmonary capillary vascular bed Am J of Med (2005) 118, 578–583 Chest (2003) 123, 2096-2103 Resp Med (2004) 98, 598-605 VO2 max (Exercise Test) • exercise capacity (measured as VO2 max) • predictor of post-op complications (including death) – – – – exercise oximetry stair climbing shuttle walking 6-minute walk test • helps to identify high-risk patients who can safely undergo lung resection Am J of Med (2005) 118, 578–583 VO2 max Eugene et al • VO2 max > 1 L/min  little complications Smith et al • VO2 max > 20 ml/kg/min  post-op complications 10% • VO2 max = 15~20 ml/kg/min  post-op complications 66% • VO2 max < 15 ml/kg/min  post-op complications 100% Markos et al • oxygen desaturation during a 12-min walk, ppoDLCO and ppoFEV1 were more reliable predictors of post-op mortality Chest (2003) 123, 2096-2103 Other Parameters • FEF25-75%: highly variable • ABG: hypercapnia (>45 mmHg) • PPP (predicted postoperative product) – product of ppoFEV1 and ppoDLCO Am J of Med (2005) 118, 578–583 Postoperative Lung Function • Pulmonary function is affected by lung resection, extent varies: – pneumonectomy: • FEV1: 34~36%↓ • FVC: 36~40%↓ • VO2 max: 20~28%↓ – lobectomy: • FEV1: 9~17%↓ • FVC: 7~11%↓ • VO2 max: 0~13%↓ Am J of Med (2005) 118, 578–583 Lung Resection • may undergoes up to 3 testing phases: • 1st phase (whole-lung tests): • room-air ABG, simple spirometry, lung volume, (DLCO, exercise test) i. PaCO2 > 45 mmHg ii. FEV1 or MVV < 50% predicted iii. RV/TLC > 50% • if any combination of the above exists → proceed to 2nd phase Chapter 49, Miller’s Anesthesiology, 6th Edition Lung Resection • 2nd phase (single-lung tests): • ventilation/perfusion of each lung • quantitative CT scanning i. ppoFEV1 < 0.85 L ii. > 70% blood flow to the diseased lung • if any of the above exists → proceed to 3rd phase Chapter 49, Miller’s Anesthesiology, 6th Edition Prediction of Post-op Lung Function • Methods to predict postoperative pulmonary function: – segment method – radionuclide scanning techniques – quantitative computed tomography Segment Method • 19 total segments (right 10, left 9) • estimated post-op pulmonary function = (pre-op pulmonary function) * (post-op remaining segments) / 19 • subsegments also being used (total of 42 subsegments) Am J of Med (2005) 118, 578–583 Radionuclide Scanning Techniques • inhaled 133Xe or intravenous 99Tc-labeled macroaggregates • estimation by quantifying the perfusion to a specific area: ppoFEV1 = preoperative FEV1 * % of radioactivity contributed by nonoperated lung Am J of Med (2005) 118, 578–583 Quantitative Computed Tomography • -500~-910 Hounsfield unit is used to estimate functional lung volume • correlates better than radionuclide scanning method AJR (2002) 178, 667–672 Lung Resection • 3rd phase (mimic post-op condition): – temporary balloon occlusion (with or without exercise) → skill-demanding, rarely performed Chapter 49, Miller’s Anesthesiology, 6th Edition Ann Thorac Cardiovasc Surg (2004) 10, 333-339 Testing Phases Chapter 49, Miller’s Anesthesiology, 6th Edition Pulmonary Function Test Chapter 49, Miller’s Anesthesiology, 6th Edition Case Pre-op Predicted Post-op FVC (L) FEV1 (L) FEV1/FVC (%) RV/TLC (%) 3.20 1.66 (>1.2~1.0) 51.9 (>40) 55.0 2.69 1.40 (>1) MVV (L/min) % predicted (%) VO2 max (L/min) VO2 max (ml/kg/min) 53.3 (>40) 69.9 (>40) 0.944 (<1) 15.9 (>15, <20) Oxy-Hb drop in exercise (%) None (<5%) The patient should therefore be safe to undergo RUL lobectomy. Reference 1. Anesthesia for thoracic surgery, Miller: Miller’s Anesthesiology (2005) 6th Edition, chapter 49 2. Pulmonary function testing, Miller: Miller’s Anesthesiology (2005) 6th Edition, chapter 26 3. Mazzone et al., Lung cancer: preoperative pulmonary evaluation of the lung resection candidate. Am J of Med (2005) 118, 578–583 4. Datta et al., Preoperative evaluation of patients undergoing lung resection surgery. Chest (2003) 123, 2096-2103 5. Wang et al., Pulmonary function tests in preoperative pulmonary evaluation. Resp Med (2004) 98, 598-605 6. Tanita et al., Review of preoperative functional evaluation for lung resection using the right ventricular hemodynamic functions. Ann Thorac Cardiovasc Surg (2004) 10, 333339 7. Wu et al., Prediction of postoperative lung function in patients with lung cancer: comparison of quantitative CT with perfusion scintigraphy. AJR (2002) 178, 667-672 Thank you for your attention! predicted VO2 = 5.8 * weight in kg + 151 + 10.1 (W of workload)