Study objectives: To evaluate correlations between
improvement in quality of life (QOL) in patients with severe COPD
before and after they undergo lung volume reduction surgery (LVRS) with
changes in pulmonary function tests, gas exchange, exercise
performance, and alterations in medical management.
Design: Case-series analysis.
Patients: Forty-two patients
(mean [± SD] age, 56 ± 8 years; 53% women) with severe airflow
obstruction (FEV1, 0.62 ± 0.2 L), and moderate to severe
hyperinflation (total lung capacity [TLC], 6.9 ± 1.7 L).
Intervention and measurements: All patients underwent
bilateral LVRS via median sternotomy. Measurements of lung function,
symptom-limited cardiopulmonary exercise testing, the total distance
the patient was able to walk in 6 min in a corridor, and sickness
impact profile (SIP) scores were made before and 3 months after LVRS.
SIP scores are inversely proportional to the level of function and
Results: Compared to baseline,
FEV1 increased (0.87 ± 0.3 vs 0.62 ± 0.2 L,
respectively; p < 0.01) while residual volume significantly
decreased (3.2 ± 1.8 vs 6.3 ± 1.2 L, respectively; p < 0.004)
at 3 months post-LVRS. On cardiopulmonary exercise testing, values
increased from baseline to post-LVRS for total exercise time
(9.0 ± 2.2 vs 6.0 ± 1.5 min, respectively; p = 0.045), maximum
oxygen uptake (V̇o2) (16 ± 3 vs
11 ± 2 mL/kg/min, respectively; p = 0.01), and maximum minute
ventilation (V̇e) (33 ± 9 vs 28 ± 5 L/min,
respectively; p = 0.03). The percentage change in the oxygen cost of
ratio) from low to high workloads during exercise was
significantly lower after LVRS (p = 0.002). There was no significant
change in oxygenation after LVRS (Pao2/fraction
of inspired oxygen, 331 ± 27 vs 337 ± 39, respectively;
p = 0.76), but Paco2 tended to be lower
(41 ± 9 vs 48 ± 6 mm Hg, respectively; p = 0.07). Overall SIP
scores were significantly lower after LVRS than before (8 ± 4 vs
15 ± 2, respectively; p = 0.002). Changes in SIP scores correlated
with the change in
V̇o2/V̇e ratio from low
to high workloads, with patients having the smallest changes in
V̇o2/V̇e ratio having the
smallest changes in SIP scores after LVRS (r = 0.6;
p = 0.01). Improved or lower SIP scores also tended to correlate with
a reduction in residual volume/TLC ratio (r = 0.45;
p = 0.09), and there was a linear correlation with a statistically
significant Pearson r value with decreased steroid
requirements (r = 0.7; p = 0.001). Moreover, changes
in psychological SIP subscore tended to correlate with diminished
oxygen requirements post-LVRS (r = 0.45; p = 0.09).
However, there was no significant correlation between changes in SIP
scores and routine measurements of lung function, exercise performance,
or gas exchange.
Conclusion: There is an association
between an improvement in QOL and reduced hyperinflation after LVRS.
Reduced hyperinflation may lead to more efficient work of breathing
during exercise and, therefore, to an increased ability to perform
daily activities. Changes in QOL scores correlate best with
behaviorally based variables that directly affect the patient’s
well-being, such as systemic steroid administration.