Preoperative Pulmonary Evaluation

Chang Shim, MD

Professor of Medicine

Jacobi Medical Center

Postoperative ComplicationsPulmonary

Pneumonia/atelectasis: abnormal CXR, fever, leukocytosis, ABGRespiratory failure/mechanical ventilationPulmonary embolism

CardiovascularCHFArrhythmiasIschemia/MIHypotension/hypertension

NeurologicalStrokePsychosis

Infection, sepsisWound, lines, others

GIRenal

Non-pulmonary Risk Factors forPost-op Pulmonary Complications

Extent and Location of SurgeryDuration of AnesthesiaAgeGenderWeight, BMI

ASA (American Society of Anesthesiology)Score 1 A normal healthy person

2 Mild systemic disease3 Systemic disease that is not incapacitating. 4 Incapacitating systemic disease that is

threatening to life5 Moribund, 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 2006

1. 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 70-79.• 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;167:741

• 22 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 RiskMaAlister FA ,et al Am J Repir Crit Care Med 2003;167:741

• 272 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 IndexArozullah, AM et al Multifactorial Risk Index for postop

pneumonia. Ann Intern Med 2001;135:847-57

• 100 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 1995-97.

• Type of surgery: abd aortic aneurysm, thor, up abd, neck, vasc, neuro• Age =>80, 70-79, 60-69, 50-59• Functional status: total dependent, partial dependent• Wt loss >10% in 6 months• Hx COPD• Others: General anesthesia, impaired sensorium, Hx CVA, BUN <8

mg/dl, Transfusion >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 VentilationCO2, Hypoxia, PatternCOPD

FRC, Airways closureDiaphragm movementAtelectasis

Respiratory pattern, O2Ventilation/perfusion matching

Dead space, shuntBronchomotor toneMucociliary 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 respirationNeuromuscular blockMechanical 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 PneumoniaAnesthesia and Surgery

Mucociliary Muscle Ventilatory PainClearance 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.

COPDComplications

Atelectasis/pneumoniaRespiratory failure/mechanical ventilation

HistoryAirflow obstruction/exercise capacitySmokingCough and sputum production

Assessment and interventionPFTs, ABGs: FEV1of 0.7 liter, pCO2 of >45 mmHgSmoking cessationAntibiotics for those who have sputum production, 3-5 days pre-opSystemic corticosteroids: prednisone 40 mg daily x 3 daysBronchodilators: beta agonists, anticholinergics, theophyllineCough and Hyperinflation maneuvers

Asthma

History and PEFRCompletely asymptomatic for 6 months or longerPEFR is normalTreatment: bronchodilator only peri-operatively

Symptoms present within 6 monthsPEFR abnormal <80% predictedPrednisone 40 mg daily x 3 pre-op and x 3 post-opIf patient is well post-operatively, discontinue it. If not well, continue prednisone until well.

Obesity

Independent risk factor for pulmonary complications particularly atelectasisRisk of hypoventilation, hypercapnea

HypoxiaObstructive Sleep Apnea (OSA)

InterventionsUpright positioningOxygen used sparinglyCPAP, 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 literPossibility of unexpected pneumonectomy Perfusion scan to estimate lung function lossFEV1 value x % residual function= FEV1 estimate

ABGs: PCO2 >45mmHg: high riskPulmonary artery hypertension mean >25 mmHgExercise test: stair climbing, 6 minute walk test: excellent

prognosticator