Pulmonary Assessment for Lung Resection 

 

 

Anesthetic Considerations

 

  • High risk group for major respiratory complications: atelectasis, pneumonia, respiratory failure

  • Identify high risk patient & focus perioperative management & clinical resources on them

  • Pre-thoracotomy (lung resection) assessment entails:

    • Pre- & post-resection pulmonary function

    • Comorbidities including cardiovascular disease & other end-organ function

    • Identification of optimization strategies - smoking cessation, pulmonary rehabilitation, stabilization of symptoms

  • Use a three-legged approach to pulmonary function assessment: FEV1, DLCO, VO2 max

 

 

Components of Pulmonary Assessment

 

  • Respiratory mechanics: how readily does atmospheric oxygen get into the alveoli

  • Pulmonary parenchymal function: how readily does oxygen get into the blood

  • Cardiopulmonary interaction: how readily does oxygen get to the tissues

 

 

Respiratory Mechanics

 

  • Most valid test for post-thoracotomy respiratory complications is predictive postoperative FEV1 (ppoFEV1%) 

    • ppoFEV1% = preoperative FEV1% x (1 - % functional lung tissue removed / 100)

      • ppoFEV1 > 40% correlates to no or minor post-resection pulmonary complications

      • ppoFEV1 < 30% correlates strongly with need for post-resection mechanical ventilation

 

 

Parenchymal Function

 

  • ABG: PaO2 < 60, PaCO2 > 45

    • Useful as warning indicators but not as predictors of complications

  • DLCO: total functioning surface area of alveolar-capillary interface

    • Predictor of perioperative morbidity & mortality

    • ppoDLCO < 40% correlates with both increased respiratory & cardiac complications & is independent of FEV1

    • ppoDLCO < 20% absolute minimum value compatible with a successful outcome due to an unacceptably high perioperative mortality rate

 

 

Cardiopulmonary Interaction

 

  • VO2 max (maximal oxygen consumption):

    • VO2 max < 15 mL/kg/min correlates with unacceptably high morbidity & mortality

    • VO2 max > 20 mL/kg/min associated with few respiratory complications

    • Estimated ppoVO2max < 10 mL/kg/min considered a contraindication to pulmonary resection

  • 6 minute walk test:

    • Excellent correlation with VO2 max

    • Total distance / 30 = VO2 max

  • Fall in oximetry (SpO2 > 4%) during exercise increases risk of morbidity & mortality:

    • Stair climbing 2 or 3 flights or equivalent

  • Stair climbing:

    • Done at the patient's own pace & without stopping

    • Documented as a number of flights

    • 1 flight = 20 steps at 6 inches/step

    • 5 flights = VO2 max > 20 mL/kg/min

    • 2 flights = VO2 max = 12 mL/kg/min

    • < 2 flights is extremely high risk

 

 

Regional Lung Function

 

  • Postoperative lung function can be modified after accounting for the lung region to be resected

  • Should be considered in:

    • Pneumonectomy patients

    • FEV1 and/or DLCO < 80% or pop values < 40% predicted

 

 

 

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