Non-pulmonary Risk Factors for Post-op Pulmonary Complications Extent and Location of Surgery Duration of Anesthesia Age Gender Weight, BMI ASA (American Society of Anesthesiology) Score 1A normal healthy person 2Mild systemic disease 3Systemic disease that is not incapacitating. 4Incapacitating systemic disease that is threatening to life 5Moribund, not expected to survive 24 hours with or without operation.
Risk Assessment for and Strategies to Reduce Perioperative Pulmonary Complications for Patients Undergoing Noncardiothoracic Surgery (ACP) Annals Intern Med April All should be evaluated for the presence of COPD, age >60 yrs, ASA class II or greater, functionally dependent, & CHF. Obesity and mild or mod asthma: not significant risk factors 2.Higher risk for complications: prolonged surgery (>3H), abdominal surgery, thoracic surgery, neurosurgery, head and neck surgery, vascular surgery, aortic aneurysm repair, emergency surgery, and general anesthesia. 3.Low serum albumin level <35 g/L. All those suspected to have low albumin or those with 1 or more risk factors. 4.Those who have higher risk for complications should have deep breathing exercise or incentive spirometry and selective use of nasogastric tube post op. 5.Preoperative spirometry and chest radiography should not be used routinely for predicting risk for postop complications. 6.Right heart cath and total parenteral nutrition should not be used to reduce pulmonary complications.
Patient-Related Risk Factors Age: odds ratio 1 for <60, 1.79 for 60-69, 3.04 for COPD: odds ratio 1.79 Cigarette Use: OR 1.26 CHF: OR 2.93 Functional Dependence: OR 2.51 for total, 1.65 for partial dependence ASA Classification I 1.2%, II 5.4%, III 11.4%, IV 10.9%, IV not available Obesity: not a risk factor Asthma: not a risk factor OSA: airway management issues but not pulmonary complication Impaired sensorium, abn chest examination, alcohol use, wt loss: inc
Procedure Related Risk Factors Surgical Site: inc risk for aortic aneurysm repair, thoracic surgery, abdominal surgery, upper abd surgery, neurosurgery, prolonged surgery, head and neck surgery, emergency surgery, vascular sur Duration of Surgery: 3-4 hours increase risks Anesthetic Technique: general vs local or regional Emergency Surgery: OR 2.21
Laboratory Testing to Estimate Risk Spirometry: value unproven except in lung resection and coronary bypass graft Chest Radiographs: 23% abn, 3% clin important Blood Urea Nitrogen: >21 risk factor, magnitude? Oro-pharyngeal Culture:? Serum Albumin Measurement:36g/L 27.6% v 7% –35 g/L threshold value is one of the most powerful risk factor.
Strategies to Reduce Postoperative Pulmonary Complications Preoperative Smoking Cessation Lung Expansion Modalities Neuromuscular Blockade: avoid pancuronium Anesthesia and Analgesia: neuraxial blockade Surgical Techniques: laparoscopic vs open? Perioperative Care –Nutritional Support, Pulmonary Artery Catheterization, Selective Nasogastric Decompression after Abdominal Surgery
Predictors of Post-operative Pulmonary Complications McAlister FA, et al. Am J Respir Crit Care Med 2003;167: general internists and pulmonologists in 10 groups, a Canadian study 272 patients referred for pre-op evaluation Exclusion: on ventilator, sleep apnea, known neuromuscular disease, cognitive impairment, intrathoracic or severe orthopedic surgery. Pulmonary complication before discharge or 7 days post Outcome: respiratory failure requiring mechanical vent, pneumonia, lung or lobar atelectasis requiring bronchoscop
Predictors of Postoperative Pulmonary Risk MaAlister FA,et al Am J Repir Crit Care Med 2003;167: referred for evaluation before nonthoracic surgery— 22 (8%) had postop pulm complications: 6 respir failure, 9 pneumonia, 7 atelectasis. Hypercapnea, pCO2 =>45 mmHg, odds ratio 66 FVC less than 1.5 liters, OR 11.1 Maximal laryngeal height =<4 cm, OR 6.9 Forced expiratory time =>9 seconds, OR 5.7 Smoking =>40 pack-years, OR 1.9 BMI =>30, OR 4.1 Multiple regression analysis: age =>65 OR 1.8, smoking 40 pk-yrs, OR 1.9, laryngeal height =<4 cm, OR 2.0
Postoperative Pneumonia Risk Index Arozullah, AM et al Multifactorial Risk Index for postop pneumonia. Ann Intern Med 2001;135: VA Hosp 160, 805 major non-cardiac surgery 9/97 to 8/99—2466 cases (1.5%) developed pneumonia. Developed risk index to predict post-op pneumonia and validated it by using cases Type of surgery: abd aortic aneurysm, thor, up abd, neck, vasc, neuro Age =>80, 70-79, 60-69, Functional status: total dependent, partial dependent Wt loss >10% in 6 months Hx COPD Others: General anesthesia, impaired sensorium, Hx CVA, BUN 4 units, emergency surgery, chronic steroid use, current smoker, alcohol >2 drinks/d Risk point system used to categorize risk class 1-5, 0-15 risk points, 16-25, 26-40, 41-55, >55, Pneumonia rates were 0.24% to 15.9%.
Respiratory Effects of General Anesthesia Control of Ventilation CO2, Hypoxia, Pattern COPD FRC, Airways closure Diaphragm movement Atelectasis Respiratory pattern, O2 Ventilation/perfusion matching Dead space, shunt Bronchomotor tone Mucociliary clearance
Postoperative Decline in Lung Function TLC and VC declined similarly FRC decreased half as much as VC RV decreased less than FRC
Diaphragmatic Function Descends during inspiration pushing down abdominal content. Lifts up thoracic cage, using inertia of abdominal content as a fulcrum Anesthesia, spontaneous respiration Neuromuscular block Mechanical ventilation
Who should have pre-op PFT evaluation? Known pulmonary disease Planned lung resection Smoker or heavy smoker? Tests:Match test: FEV1 of 1.8 liters Spirometry (FVC,FEV1), PEFR Diffusion capacity ABGs
Types of Anesthesia General vs spinal Regional
Atelectasis and Pneumonia Anesthesia and Surgery Mucociliary MuscleVentilatory Pain Clearance Weakness Drive Narcotics Shallow breathing Cough Atelectasis V/Q mismatch Hypoxia/infection
Lung Hyperinflation Maneuvers Adequate analgesia and motivation are necessary. Cough and deep breathing: preferably trained pre- operatively. Incentive spirometer: excellent device rarely used efficiently. Would pre-op training help? CPAP or BiPAP for a few minutes every 2-4 hours (10 to 20 cm water pressure) is more effective.
COPD Complications Atelectasis/pneumonia Respiratory failure/mechanical ventilation History Airflow obstruction/exercise capacity Smoking Cough and sputum production Assessment and intervention PFTs, ABGs: FEV1of 0.7 liter, pCO2 of >45 mmHg Smoking cessation Antibiotics for those who have sputum production, 3-5 days pre-op Systemic corticosteroids: prednisone 40 mg daily x 3 days Bronchodilators: beta agonists, anticholinergics, theophylline Cough and Hyperinflation maneuvers
Asthma History and PEFR Completely asymptomatic for 6 months or longer PEFR is normal Treatment: bronchodilator only peri-operatively Symptoms present within 6 months PEFR abnormal <80% predicted Prednisone 40 mg daily x 3 pre-op and x 3 post-op If patient is well post-operatively, discontinue it. If not well, continue prednisone until well.
Obesity Independent risk factor for pulmonary complications particularly atelectasis Risk of hypoventilation, hypercapnea Hypoxia Obstructive Sleep Apnea (OSA) Interventions Upright positioning Oxygen used sparingly CPAP, BiPAP, Incentive spirometry
Lung Resection Candidate Goal: adequate remaining lung to sustain independent breathing (free of ventilator) Residual FEV1 of at least 800 ml, VC of 1 liter Possibility of unexpected pneumonectomy Perfusion scan to estimate lung function loss FEV1 value x % residual function= FEV1 estimate ABGs: PCO2 >45mmHg: high risk Pulmonary artery hypertension mean >25 mmHg Exercise test: stair climbing, 6 minute walk test: excellent prognosticator