Pre-operative Pulmonary
Evaluation
BY
ESSAM SHARKAWY
Prof of Anesthesia & ICU
Preoperative risk
assessment
• Resective thoracic surgery
• Extra-thoracic and thoracic surgery
without lung resection
Resective thoracic surgery
• Clinical evaluation
– History & PE
• Pulmonary function test
– Spirometry & Blood gas analysis
• Split lung function studies
• Cardopulmonary exercise test
Clinical evaluation
• Complete history
– Smoking, poor exercise tolerance, unexplained
dyspnea or cough
– unrecognized chronic lung disease should be
determined
• Good physical examination
– directed toward evidence for obstructive lung
disease
– decreased breath sounds, wheezes, rhonchi, or
prolonged expiratory phase
Pulmonary function testing
• all candidates for lung resection should
have preoperative PFT
• PFTs should not be ordered routinely prior to
abdominal surgery or other high risk
surgeries
– Patients undergoing coronary bypass or upper
abdominal surgery with a history of smoking or
dyspnea.
– Patients undergoing head and neck, orthopedic, or
lower abdominal surgery with unexplained
dyspnea or pulmonary symptoms
Pulmonary function
testing(cont.)
• These tests simply confirm the clinical
impression of disease severity in most
cases, adding little to the clinical
estimation of risk
• There has also been concern that
preoperative PFTs are overused and a
source of wasted health care dollars
Pulmonary function
testing(cont.)
• PFTs should not be used as the primary
factor to deny surgery
• the results from PFT should be interpreted in
context of clinical situation and should not be
the sole reason to withhold necessary
surgery
• Most patients with abnormal spirometry would
be apparent based on history and physical
examination
Pulmonary function
testing(cont.)
• Two reasonable goals to use of preoperative
PFTs
– Identification of a group of patients for whom the
risk of the proposed surgery is not justified by the
benefit
– Identification of a subset of patients at higher risk
for whom aggressive perioperative management is
warranted
Pulmonary function
testing(cont.)
• Spirometry
– performed when the patient is clinically stable and
receiving maximal bronchodilator therapy
– Risky for Pneumonectomy
• FEV1< 60% of the predicted value or < 2 liters
• DLCO< 60% of the predicted value
• MVV< 50% of the predicted value
– Safe lower limit for Pneumonectomy
• FEV1> 80% of the predicted value or > 2 liters
– Safe lower limit for Lobectomy
• FEV1>1.5 litres or > 60% of the predicted value
Pulmonary function
testing(cont.)
• Blood gas analysis
– Current data do not support the use of
preoperative arterial blood gas analyses to stratify
risk for postoperative pulmonary complications
– Hypoxemia: SaO2 < 90%
– Hypercapnia: PaCO2 > 45mmHg
• not necessarily an absolute contraindication for surgery
• lead to a reassessment of the indication for the proposed
procedure and aggressive preoperative preparation
Pulmonary function
testing(cont.)
At-risk p’t require a closer diagnostic examination to
estimate the likely post-resection pulmonary reserve
Split lung function studies
• Predicting post-resection pulmonary function
• Predicted postoperative FEV1 (ppoFEV1) is
the most valid single test available
– ppoFEV1 = preoperative FEV1 × (1– %functional
tissue removed/100)
– lung function can be calculated by counting the
number of segments removed
• The lungs contain 19 segments (3 right upper lobes, 2
right middle lobes, 5 right lower lobes, 3 left upper lobes,
4 left lower lobes, 2 left lingula)
Split lung function
studies(cont.)
– Ventilation-perfusion(V/Q) scan
• allows detailed assessment of the functional capacity of
the lung and accurate determination of which lobes or
segments contribute proportionally to ventilation and
perfusion before their resection
• Allows the calculation of the functional remaining
parenchyma after surgery and the predicted postresection FEV1 value
• Correlations between the predicted and observed postresection FEV1 values have proved to be good, although
errors tend to underestimate postoperative function
– Quantitatve CT
Split lung function
studies(cont.)
• FEV1ppo > 40%, DLco ppo > 40%
– Widely accepted as a predictor of average risk for
complications
• FEV1ppo < 40%, DLco ppo < 40%
– High risk of perioperative complications including
death
– FEV1ppo <1L → sputum retention
– FEV1ppo <0.8L → preclude resection , dependent
on a ventilator
• Post-operative lung function shows borderline
values → Cardiopulmonary exercise test
Cardiopulmonary exercise
test
• stress the entire cardiopulmonary and oxygen
delivery system → expect the functional reserve after
pulmonary resection
• Maximal oxygen uptake (VO2max)
– VO2max > 20mL/kg/min
• are not at increased risk for complications or death
– VO2max < 15 mL/kg/min
• an increased risk of peri-operative complications
– VO2max < 10 mL/kg/min
• a very high risk for post-operative complications or death
WHICH ONE OF THE EXERCISE TESTS SHOW HIGHER
CORRELATION WITH VO2 MAX. ???
1. 6MWT (6 minute walking test)
2. Stair climbing test
3. "Shuttle walk"
PERFORMANCE EXERCISE TESTS
• Stair climbing test
• 6 - 12 minute walking test: Submaximal test
(Correlation with VO2max r= 0.4 – 0.6 )
• 10 meters “Shuttle walk” test. Progressive maximal test (Correlation
with VO2max r=0.98 )
17
British Thoracic Society Thorax
2001;56: 89-108
SPIROMETRY
LOBECTOMY
PNEUMONECTOMY
FEV1>1500 ml
No
FEV1>2000 ml
No
Yes
Surgery
FURTHER EXAMINATION
•Quantitative scintigraphy
•DLCO
•ABG
•Exercise tests (selected cases)
Post-op FEV1 > % 40
Post-op DLCO > % 40
SaO2
> % 90
Acceptable risk
Post-op FEV1 < %
40
Post-op DLCO < %
40
18
High risk
British Thoracic Society Thorax 2001;56: 89108
EXERCISE TEST – SURGICAL RISK
RELATION
EXERCISE TEST
< 25 ‘shuttle walk’
> 25 ‘shuttle walk’
> % 4 desaturation
< % 4 desaturation
High risk
Cardiopulmonary exercise
test
Minor surgery
Radical RT
VO2max < 15 mL/kg/min
VO2max > 15 mL/kg/min
High risk
Acceptable risk
19
Assessment of p’t candidate for
lung resection
Thanks for your listening!