Lung resection

Pre operative evaluation of lung resection

1. PRE OPERATIVE LUNG FUNCTION TESTING FOR LUNG RESECTION DR ANUSHA CM

2. INTRODUCTION Lung resection is an expanded procedure that includes resection of the parietal and visceral pleurae, diseased lung, ipsilateral hemi-diaphragm, ipsilateral pericardium, and mediastinal lymph nodes Indications 1. Malignant Pulmonary metastasis Non small cell lung carcinoma

3. 2. Benign Chronic lung infection (multiple abscesses,  bronchiectasis , fungal infection,tuberculosis ) Traumatic lung injury Bronchial obstruction with destroyed lung Congenital lung disease

4. TYPES OF LUNG RESECTION LOBECTOMY- Removal of one lobe BILOBECTOMY- Removal of 2 or more lobes PNEUMONECTOMY- Removal of whole lung WEDGE RESECTION- Removal of an area of the lung that includes part of one or more lobes.

5. 4. SEGMENTECTOMY- Removal of areas of the lung along with their veins, arteries and airways. 5. SLEEVE RESECTION- Removal of  the affected section of the bronchus and any surrounding cancer in the lobe 6. LYMPHADENECTOMY- Removal of metastatic lymph nodes

6. APPROACHES THORACOTOMY – incision is made around the side of chest VATS – Also called key hole surgery , done via laparoscope connected to a fibro optic camera

7. CHANGES IN PULMONARY FUNCTIONS WITH SURGERY

8. PRE- OPERATIVE RISK FACTORS 1. COPD Incidence of postoperative pulmonary complications in patients with COPD varies from 10% to greater than 50% Complications increase significantly when the FEV1 is below 65% of predicted

9. An increase in the Closing Capacity favors development of areas of low ventilation-to-perfusion ratios and atelectasis Smokers have impaired ciliary function with tracheobronchitis adding as contributory factor

10. 2. RESTRICTIVE LUNG DISEASE IN RLD , FRC is reduced , favoring the formation of areas of poor ventilation and atelectasis , also coughing and the ability to clear respiratory secretions are impaired.

11. Most commonly seen in (1 ) sarcoidosis complicated by aspergilloma and hemoptysis (2) corrective surgery for kyphoscoliosis (3) myasthenia gravis with associated thymoma

12. 3. OBSTRUCTIVE SLEEP APNEA Unrecognized OSA is significant, because both anesthesia and surgery affect sleep architecture, also use of postoperative narcotics for analgesia may further blunt ventilatory chemosensitivity , suggesting that postoperative respiratory morbidity is likely higher in patients with OSA than in the general population

13. It can be used as an opportunity to screen for OSA, the value of preoperative screening for OSA as a means of decreasing postoperative pulmonary complications

14. 3. SMOKING HISTORY Smoking increases the risk of postoperative respiratory complications, even among those without COPD A statistically significant reduction in complications occurs only when patients discontinue smoking for at least 8 weeks prior to surgery

15. 4. GENERAL STATE OF HEALTH Overall clinical status, as categorized by the American Society of Anesthesiologists’ (ASA) classification , correlates with development of postoperative pulmonary complications. Specifically, an ASA classification of II or higher is a powerful predictor of increased risk for respiratory problems after surgery

16. 5. AGE Although increased age was previously thought to be a minor risk factor for postoperative respiratory complications,more recent analyses indicate that increasing age is, in fact, a significant independent predictor, even after accounting for comorbid conditions associated with aging

17. In a study , in patients over age 70 years who underwent resectional lung surgery, the incidence of postoperative pulmonary complications and hospital stay were not increased, and survival was not decreased Thus treatment decision should be individualised to each patient

18. 6. OBESITY The accumulation of fat in the chest wall, diaphragm, and abdomen may reduce total respiratory compliance by more than 60%— a change that is amplified when the patient assumes the supine position

19. Spirometry shows reduction in ERV Areas of low ventilation relative to perfusion and atelectasis are seen and also predisposed to aspiration ( high gastric volume and low pH)

20. 7. NUTRITIONAL STATUS The effects of malnutrition and severe starvation on the respiratory system include a reduced ventilatory response to hypoxia, decreased diaphragmatic muscle function, impaired cell-mediated and humoral immunity, and alterations in the elastic properties of the lung

21. Malnutrition are associated with expiratory muscle weakness (despite preservation of pulmonary function) and an increased incidence of postoperative respiratory complications

22. PREOPERATIVE EVALUATION HISTORY AND EXAMINATION Smoking history History of respiratory symptoms (e.g., cough, chest pain, dyspnea ), including symptoms of sleep apnea Extent of pre-existing lung disease History of recent respiratory tract infection

23. 2. CHEST RADIOGRAPH The preoperative chest radiograph is usually unrevealing if risk factors and abnormal physical findings are absent. A preoperative chest radiograph is indicated when there are new or unexplained symptoms or signs, when there is a history of underlying lung disease and no recent chest radiograph, or when thoracic surgery is planned

24. 3. ARTERIAL BLOOD GAS ANALYSIS Elevated PaCO2 is associated with an increased incidence of postoperative respiratory morbidity in patients with significant chronic lung disease The determination serves as a basis for comparison with subsequent intra- and postoperative measurements

25. POST OPERATIVE COMPLICATIONS Acute CO2 retention (PaCO2 > 45 mm Hg) Prolonged mechanical ventilation (> 48 h) Infections (bronchitis & pneumonia) Atelectasis (necessitating bronchoscopy ) Bronchospasm Exacerbation of the underlying chronic lung disease Pulmonary embolism Symptomatic cardiac arrhythmias Myocardial infarction Death

26. EVALUATION FOR LUNG RESECTION 1.PULMONARY FUNCTION TESTING 2. PREDICTION OF POST OPERATIVE FEV1 OR DLCO 3. CARDIO PULMONARY EXERCISE TESTING

27. 1.PULMONARY FUNCTION TESTING To assess the risk of post operative complications , spirometry is needed to evaluate for airway obstruction and the degree of restriction (as assessed by lung volumes)

28. Indications for pre op pulmonary function testing Presence of cough or Unexplained dyspnea History of chronic lung disease History of cigarette smoking (>20 packyears ), Planned lung resection

29. Studies dating back to the 1950s have shown that the risk of postoperative respiratory complications following pneumonectomy increases significantly when the FEV1 is less than 2 L or 80% of predicted normal, or when the maximal voluntary ventilation (MVV) is less than 50% of predicted.

30. For a lobectomy , an FEV1 of 1.5 L appears to be the critical threshold. The diffusion capacity for carbon monoxide (DLCO) has also been identified as a predictor of postoperative complications.

31. Increased risk is associated with a DLCO of less than 60% to 80% of predicted and appears to be independent from FEV1 as a predictor of complications, morbidity, and death. Therefore ,predictive postoperative lung function should be estimated for patients with an FEV1 or DLCO less than 80% of predicted .

32. SPLIT FUNCTION STUDIES The estimation of post operative lung function is based on hypothesis that each segment of resected lung contributes to a fixed percentage of lung function Juhl and Frost compared pre and post operative lung function and suggested that each lung segment resected would decrease lung function by 5.26%

33. According to BTS guidelines, estimated FEV1 is calculated by Estimated post op FEV1+ pre op FEV1 X [19-a)-b)] / 19 –a Where a and b are no of segments, respectively to be resected Guidelines suggest that estimated post op FEV1 > 40% is above the threshold of avg risk for complication after lung resection

34. 2. PREDICTION OF POST OPERATIVE FEV1 OR DLCO Ventilation–perfusion lung scans measure the relative blood flow or ventilation to one lung or lung region and can be used to predict postoperative FEV1 or DLCO using the following equation An alternative approach to estimating the predicted postoperative pulmonary function involves a calculation based on the number segments of the lung (10 on the right and nine on the left)

35. For right upper lobectomy (3 segments) in a patient with a preoperative FEV1 of 1.6 litre which is 80% of predicted normal, the ppo -FEV will be 1.6x16/19 = 1.35 litre , and the ppo-FEV1% will be 80%x 16/19 = 67%. The same form of ppo calculation may be applied to the measured DLCO or the DLCO as a percentage of the predicted normal value.

36. A number of studies have demonstrated that the perioperative risk for lung resection increases significantly when the predicted postoperative FEV1 or DLCO has <40% of predicted Therefore, a predicted postoperative FEV1 or DLCO ≥40% predicted has been proposed as useful criteria for undertaking “safe” pulmonary resection

37. 3. CARDIO PULMONARY EXERCISE TESTING Cardiopulmonary exercise testing (CPET) is a non-invasive technique that involves sub maximal and maximal treadmill or bicycle exercise with continuous ECG monitoring and breath-by-breath determination of oxygen uptake and carbon dioxide output, and spirometry.

38. Patient undergoing CPET

39. Measurement of maximal oxygen consumption (VO2max) during cardiopulmonary exercise testing to be useful in predicting postoperative morbidity and mortality Specifically, a V2Omax of less than 15 to 20 mL /kg/min is associated with an increased incidence of postoperative complications.

40. The risk for perioperative complications has been reported to be higher with lower measured VO2max • VO2 max > 20 ml/kg/min or > 75% predicted: - can safely safely undergo the planned resection (up to pneumonectomy ) VO2 max between 10-15 ml/kg/min or between 35%- 75% predicted: - indicates an increased risk of perioperative death compared with higher values of VO2 max. VO2 max of < 10% predicted: - very high risk for postoperative death - generally regarded as a contraindication to major anatomic resections

41. Other alternative tests include stair climbing and a walking test, can be used to assess a patient’s fitness for lung resection.

42. STAIR CLIMBING TEST Can used be as a first-line functional screening test to select those patients that can undergo safely to operation ( height of ascent > 22 m ) Demonstration of a patient’s ability to climb five flights of stairs predicts V2Omax >20 mL /kg/min Patients who are unable to climb one flight of stairs have a V2Omax <10 mL /kg/min

43. Limitation of test : lack of standardization - the duration of stair climbing, the speed of ascent, the number of steps per flight, the height of each step, and the criteria for stopping the test have varied from study to study.

44. An ability to climb three flights of stairs reliably identifies patients who are likely to do well after a lobectomy , despite having a predicted postoperative FEV1 or DLCO that is <40% of predicted . The shuttle walk and 6-minute walk tests have also been used as alternatives to cardiopulmonary exercise testing.

45. For the shuttle walk , the patient walks back and forth over a distance of 25 m at a progressively faster rate. Inability to complete 25 shuttles approximates a <10 mL /kg/min. A 6-minute walk distance >1000 ft has been reported as predictive of successful surgical outcome

46. Cardiopulmonary exercise testing is used to further assess the operability of patients of who would be at high risk for surgery based on determination of predicted postoperative pulmonary function

47. SEQUENTIAL APPROACH FOR EVALUATION OF LUNG RESECTION

48. The approach is adapted from recommendations of the American College of Chest Physicians (ACCP) The approach is predicated on determining the patient’s operability for pneumonectomy , should this procedure be deemed necessary at the time of surgery (e.g., to permit complete removal of a tumor or to deal with an unanticipated intraoperative complication)

49. PREOPERATIVE PULMONARY PREPARATION Pulmonary function in patients with obstructive airway disease should be optimized. Therapy includes any or all of the following: bronchodilators, corticosteroids, antibiotics (when there is evidence of infection), and chest physiotherapy (if excessive secretions are present).

50. When possible, these interventions should be implemented 48 to 72 hours prior to surgery. Ideally, for at least 8 weeks prior to surgery, smoking should be discontinued.

51. Program of inspiratory muscle training for at least 2 weeks prior to surgery may reduce the incidence of postoperative pulmonary complications in patients at high risk for their development. Finally, patient education on the importance of postoperative coughing and pain control, proper use of an incentive spirometer , and deep breathing exercises should take place preoperatively

52. SUMMARY All patients being considered for lung resection should undergo preoperative physiologic evaluation. Pulmonary function testing using spirometry (FEV1 ), DLCO and VO2 max help predict the risk of post-operative complications and mortality. Predicting postoperative lung function using the proportion of lung segments to be resected , perfusion scanning, or other methods is important for assessing surgical risk. Current international guidelines provide algorithms for preoperative risk assessment.

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