Pulmonary Psysiologic Assessment of Operative Risk

1. Pulmonary Psysiologic Assessment of Operative Risk

3. Effects of surgery on pulmonary function ♦ Pulmonary, esophageal, upper abdomen surgery ♦FRV=ERV+RV→post op pulmonary complications ♦ Post-op ↓FRV: general anesthesia, increased intraabdominal pressure, lower abdomen: ↓ 10-15% upper abdomen: ↓ 30% thoracotomy: ↓35%

4. Upper abdomen surgery ♦ Dysfunction of abdominal musculature ♦ Impaired diaphragm function ♦ Post-operative pain ♦ Reflex inhibit phrenic

5. Sternotomy ♦ Uncoordinated rib cage expansion: structural alternation in chest wall mechanism decreased blood flow to intercostal muscle

6. Thoracotomy ♦ Restricted chest wall motion ♦ Impaired diaphragm activity ♦ Loss of pulmonary parenchyma

8. Predictive Factors for Postoperative pulmonary morbidity and mortality

9. Lung volume measurement ♦ Vital capacity (VC) ♦ Total lung capacity (TLC)

10. ↓ VC,TLC, RV, FRC Pulmonary fibrosis, sarcoidosis, muscular weakness, chest wall deformity, large diaphragmatic herniation ↓VC, ↑TLC, RV, FRC Emphysema, chronic bronchitis, asthma

11. Spirometry

12. ♦FEV1: forced expiratory volume in 1 second ♦Vital capacity: less than 60-70% of predicted ♦ FEV1: <1.64 L increased risk <1.2 L very high risk

13. Predicted Postoperative Function ♦ Bronchospirometery, unilateral pulmonary artery occlusion, lateral position test ♦ Sangalli(1992): pneumonectomy, pre-op FEV1 less than 2 L ♦ Kristerson(1972): ppo FEV1 < 1 L ♦ Olsen(1975): ppo FEV1 < 0.8 L

15. ♦ However postoperative predicted values after resection can underestimate or over estimate FEV1—250 ml ♦ Quantitative computed tomography

17. Spirometery Expressed as a Percentage of Predicted Normal Vales ♦ Kolman(1986): pre-op FEV1 < 67% ♦ Dales(1993): pre-op FEV1 < 60% 2.5 fold pulmonary complication ♦ Pate(1996): pre-op FEV1 < 40%, limit for safe major lung resection ♦ Markos(1989): 50 % mortality occurred in ppo FEV1 < 40%

18. Diffusion Capacity ♦ DLCO: diffusion capacity of lung for carbon monoxide ♦ Gas-exchange function at alveolar capillary interface ♦ Volume and surface area of the capillary bed in contact with alveolar gas ♦ Emphysema, obliterate capillaries (vasculitis, embolic disease), inflammatory interstitial disease

20. ♦ Dietiken(1960): chronic decrease in DLCO after lung resection: wedge:20% lobectomy:30% pneumonectomy: 41% ♦ Pre-op DLCO: < 60% high risk for post-op complication ♦ Markos(1989): ppo DLCO <40% excess risk

22. Exercise capacity and oxygen consumption ♦VO2 max: maximum oxygen consumption during exercise ♦ Performance: ventilatory function, gas exchange, cardiac function, cardiopulmonary condition ♦ One form exercise test: complete a fixed exercise challenge (numbers of steps, stair, walking for 6 min)

23. ♦ Oxygen uptake, carbon dioxide output, minute ventilation, blood pressure, ECG, pulse oximeter ♦ VO2 max: less than 10 ml/kg/min more than 15 ml/kg/min

25. Blood Gas ♦ Markos(1989): PaO2 < 50-60 mmHg: contraindication

26. Pulmonary Hemodynamics ♦ Intra-op assessment of pulmonary artery pressure during unilateral pulmonary artery occlusion before proceeding with pneumonectomy

27. Age ♦ Grinsber(1983): mortality rates more than double for each decade of age increase above the age of 60 y/o.