Case Study:
Lung Volume Reduction Surgery
Chronic Obstructive Pulmonary Disease (COPD) traditionally is a process
that involves a slow decline in pulmonary function over many years.
Sequential PF testing which includes spirometry, DLCO and body plethysmography,
typically reveal a decreasing FEV1 and the subsequent increases in TLC
and RV due to advancing hyperinflation and increased air trapping. DLCO
will decrease and arterial blood gases will show hypoxia and hypercapnia.
The enlarged, overexpanded lungs push the diaphragm down, putting the
respiratory muscles at a disadvantage. As a result of these physiological
changes, exercise tolerance decreases and shortness of breath increases
until the patient is unable to perform even simple tasks of daily self
care.
Lung Volume Reduction Surgery (LVRS) pioneered by Dr. Joel Cooper in
St. Louis shows promise as a treatment for this terminal illness. LVRS
involves a median sternotomy with selective resection of the most diseased
lung parts, removing 20% - 30% of the volume of each lung. The goal
of the surgery is to reduce the lung size to a more appropriate shape
to fill the thorax in a normal manner. The expected result would be
a decrease in the hyperinflation and air trapping, improvements in ventilation,
and increased efficiency of the respiratory muscles. The rib cage and
diaphragm are able to return to their normal shape because the lungs
are reduced in size and allowed to contract and expand more efficiently
while breathing.
Case Study
A 71-year-old male with severe emphysema was evaluated in 1995 at the
University of Minnesota hospital for LVRS. Pre-op pulmonary function
tests reveal a severe airflow obstruction, hyperinflation, severe air
trapping, reduced DLCO (50% of predicted), and ABGs which showed hypoxia
on room air (PaO2 65). A VQ scan, as expected, showed heterogeneous
changes in both perfusion and ventilation. Exercise tolerance is poor
with O2 saturation dropping on 2 L O2 with any exertion. Patient is
a previous cigarette smoker and smoked for 45 years, ~60 pk/years. Medications
include digoxin, verapamil, prednisone, albuterol and bactrim. He was
considered a good candidate for LVRS since his condition was primarily
pulmonary without cardiac involvement.
|
Pre-Op
|
Post-Op
|
| FEV1 (Liters) |
.93 |
31% Predicted |
1.40 |
47% Predicted |
| RV (Liters) |
6.24 |
261% Predicted |
4.87 |
204% Predicted |
| TLC (Liters) |
9.27 |
138% Predicted |
7.21 |
107% Predicted |
The surgery went well, although his hospital stay was complicated by
pneumonia and prolonged air leaks. Post-op radiology reports state "I
compared lateral views of his chest x-rays pre and post lung reduction
surgery and there is a striking reduction in the size of the lungs and
the diaphragm has elevated to near normal position". Post-op PFTs
show a marked improvement in FEV1, decrease in RV, and a normal TLC.
With LVRS patients, it is common to remove approximately 20-30% of
each lung, suggesting the TLC will decrease by this same percent. These
findings are consistent with this study, where the TLC decreased by
2.06 liters, or a 22% reduction in measured TLC. Pulmonary tests will
be used to follow this patient to see if the COPD returns. His exercise
tolerance improved and he is able to walk over a block with SOB, ride
his stationary bike for 15 minutes and is now free of supplemental oxygen.
Acknowledgement
Ed Corazalla, Clinical Pulmonary Specialist, Pulmonary Lab, University
of Minnesota, Minneapolis, MN
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