Advice:

1. 1. •FEV1 > 40% predicted for age and height is adequate for lobectomy
      

   2. •FEV1 > 60% predicted for age and height is adequate for pneumonectomy
      

   3. - provided there is no intrinsic lung disease
      

2. Historical
   

1. As the result of a number of studies going back as far as the 1970's it was stated that:
   

2. "FEV1 of 0.8 - 1 L is necessary to avoid chronic ventilatory insufficiency". If FEV1 < 1 L the incidence of CO2 retention rises, exercise tolerance decreases and mortality rate from respiratory insufficiency > 10% per year.
   

3. The following were advised as criteria for fitness for lung resection.
   

1. •FEV1 > 2L then will withstand pulmonary resection, provided there is no intrinsic lung disease such as fibrosis, asbestosis etc and no unexpected disability due to shortness of breath.
   

2. •FEV1 = 1 - 2L - further assessment is necessary,
   

3. •FEV1 < 0.8 - 1L - at high risk of respiratory failure if lobectomy or pneumonectomy performed.
   

4. 
   

5. References:
   

1. •Houshy SF et al (Chest 1971;59:383-91), 
   

2. •Wernly and Demeester ( J Thorac Cardiovasc Surg 1980;80:535-43)
   

3. •Miller JI (J Thorac Cardiovasc Surg 1993;105:347-52)
   

3. 
   

British Thoracic (physician’s) Society Guidelines

1. 1. The BTS guidelines(2001) state that:
      

   2. "No further respiratory function tests are required
      

   1. •for a lobectomy if the post-bronchodilator FEV1 is >1.5 litres  and
      

   2. •for a pneumonectomy if the post-bronchodilator FEV1 is >2.0 litres,
      

   3. - provided there is no evidence of interstitial lung disease or unexpected disability due to shortness of breath."
      

   3. Be careful - some physicians have interpreted this as carte blanche not to perform any further testing. Here in Belfast many patients have been exposed to asbestos, linen dust and other respiratory pathogens and interstitial lung disease is common. A transfer factor is virtually mandatory in all cases. Remember, you will be the one who has to explain to the relatives why the patient died of unexpected interstitial lung disease, NOT the physician!
      

2. Correction for site age and height.
   

1. A criticism of the above advice is that there was a preponderance of men in these studies and that the risk was over-estimated in women.
   

2. Percentage predicted values would be preferable, particularly in female patients. 
   

3. Calculating postoperative predicted FEV1 (and transfer factor)
   

There is a degree of logic in judging the postoperative lung function rather than the preoperative function. Predicted postoperative lung function can be calculated by two methods:

1. 1.Quantitative Ventilation/Perfusion Lung Scans.
   

1. 
   

2. Predicted FEV1 = Preop. FEV1  x % perfusion.
   

3. Wernly and Demeester performed Xenon 133 ventilation scans, technetium 99m perfusion scans, and preop. spirometry  in 85 patients undergoing 45 pneumonectomies and 40 lobectomies. (Wernly and Demeester J Thorac Cardiovasc Surg 1980;80:535-43.)
   

4. In calculating predicted FEV1 after pneumonectomy, the actual post-operative result correlates better with perfusion scans than ventilation scan. Matched V-P scans also have a good correlation. I suspect that most patients requiring pneumonectomy have central hilar node disease. Nodes tend to obstruct pulmonary arteries before obstructing bronchi so perfusion scans best predict the extent of the disease.
   

5. Please note that when requesting a ventilation/perfusion scan it is important to request “with quantitation”. Otherwise you will get a report “no evidence of pulmonary embolism”!
   

2. 2.Subtraction method for calculation of segments to be resected
   

1. For predicted FEV1 after lobectomy calculation using ventilation or perfusion scans was no more accurate than using a simple subtraction method:
   

3. Expected loss of function = Preop. FEV1 x    (No. of functional segments in lobe)
   

                                                                        (Total No. segments in both lungs)

If segments obstructed:

1. 1. 1. epoFEV1 = preFEV1 x    (19-a-b)
         

      2.                                                  (19-a)
         

2. 
   

1. 1. a = no. of obstructed segments
      

   2. b = no. of unobstructed segments to be resected
      

3. 
   

FEV1/FVC ratio

Note that I have made no mention of the FEV1/FVC ratio. It is not an accepted measure of fitness for lung resection. It is a measure of bronchial constriction and, as such, is an indicator of COPD. It should be taken into account in predicting the need for postoperative bronchodilators and other secretion clearance techniques (minitrach or bronchoscopy) but on its own is usually not a reason to turn a patient down for surgery.

Arterial Blood Gases

Arterial blood gases are useful in quantitating the degree of COPD and the likehood of developing postoperative respiratory failure or requiring supplemental home oxygen.

Unfortunately there is a reluctance on behalf of ward medical staff and respiratory physicians to obtain ABG’s and we have got into the habit of not asking for them.

The following are indicators of high risk for lung resection:

1. •pCO2 > 45 mmHg, or > 7.5 kPa
   

2. •pO2 < 60 mmHg or < 10 kPa
   

3. •be cautious of patients who de-saturate significantly on exercise, e.g. stair test