Preoperative%20Pulmonary%20Evaluation

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Preoperative Pulmonary Evaluation

• Chang Shim, MD
• Professor of Medicine
• Jacobi Medical Center

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Postoperative Complications

• Pulmonary
• Pneumonia/atelectasis abnormal CXR, fever,
  leukocytosis, ABG
• Respiratory failure/mechanical ventilation
• Pulmonary embolism
• Cardiovascular
• CHF
• Arrhythmias
• Ischemia/MI
• Hypotension/hypertension
• Neurological
• Stroke
• Psychosis
• Infection, sepsis
• Wound, lines, others
• GI
• Renal

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Non-pulmonary Risk Factors forPost-op Pulmonary
Complications

• Extent and Location of Surgery
• Duration of Anesthesia
• Age
• Gender
• Weight, BMI
• ASA (American Society of Anesthesiology)
• Score 1 A normal healthy person
• 2 Mild systemic disease
• 3 Systemic disease that is not incapacitating.
  4 Incapacitating systemic disease that is
  threatening to
  life
• 5 Moribund, not expected to survive 24 hours
  with or
  without operation.

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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 gt60 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
   (gt3H), abdominal surgery, thoracic surgery,
   neurosurgery, head and neck surgery, vascular
   surgery, aortic aneurysm repair, emergency
   surgery, and general anesthesia.
3. Low serum albumin level lt35 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.

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Patient-Related Risk Factors

• Age odds ratio 1 for lt60, 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

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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

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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 gt21 risk factor, magnitude?
• Oro-pharyngeal Culture?
• Serum Albumin Measurement36g/L 27.6 v 7
• 35 g/L threshold value is one of the most
  powerful risk factor.

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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

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Predictors of Post-operative Pulmonary
ComplicationsMcAlister FA, et al. Am J Respir
Crit Care Med 2003167741

• 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

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Predictors of Postoperative Pulmonary
RiskMaAlister FA ,et al Am J Repir Crit Care Med
2003167741

• 272 referred for evaluation before nonthoracic
  surgery22 (8) had postop pulm complications 6
  respir failure, 9 pneumonia, 7 atelectasis.
• Hypercapnea, pCO2 gt45 mmHg, odds ratio 66
• FVC less than 1.5 liters, OR 11.1
• Maximal laryngeal height lt4 cm, OR 6.9
• Forced expiratory time gt9 seconds, OR 5.7
• Smoking gt40 pack-years, OR 1.9
• BMI gt30, OR 4.1
• Multiple regression analysis age gt65 OR 1.8,
• smoking 40 pk-yrs, OR 1.9, laryngeal height
  lt4 cm, OR 2.0

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Postoperative Pneumonia Risk IndexArozullah, AM
et al Multifactorial Risk Index for postop
pneumonia. Ann Intern Med 2001135847-57

• 100 VA Hosp 160, 805 major non-cardiac surgery
  9/97 to 8/992466 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 gt80, 70-79, 60-69, 50-59
• Functional status total dependent, partial
  dependent
• Wt loss gt10 in 6 months
• Hx COPD
• Others General anesthesia, impaired sensorium,
  Hx CVA, BUN lt8 mg/dl, Transfusion gt4 units,
  emergency surgery, chronic steroid use, current
  smoker, alcohol gt2 drinks/d
• Risk point system used to categorize risk class
  1-5, 0-15 risk points, 16-25, 26-40, 41-55, gt55,
  Pneumonia rates were 0.24 to 15.9.

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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

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Postoperative Decline in Lung Function

• TLC and VC declined similarly
• FRC decreased half as much as VC
• RV decreased less than FRC

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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

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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

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Types of Anesthesia

• General vs spinal
• Regional

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Atelectasis and Pneumonia

• Anesthesia and Surgery
• Mucociliary Muscle Ventilatory Pain
• Clearance Weakness Drive
• Narcotics
• Shallow breathing Cough
• Atelectasis
• V/Q mismatch
• Hypoxia/infection

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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.

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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 gt45
  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

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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 lt80 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.

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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

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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 gt45mmHg high risk
• Pulmonary artery hypertension mean gt25 mmHg
• Exercise test stair climbing, 6 minute walk
  test excellent prognosticator