Table 3.

Studies on lung volume reduction surgery in patients with hypercapnic respiratory failure.

Study	Number of patients with HRF	Severity of HRF (PaCO2)	Outcome
Argenziano et al. [1996]	9	>55 mmHg	Improvement in pulmonary function. Improvement in exercise capacity. Improvement in dyspnea.
Albert et al. [1998]	12	>45 mmHg	Decrease in PaCO2 from 53 ± 6 mmHg to 47 ± 5 mmHg.
Wisser et al. [1998]	22	⩾45 mmHg	Decrease in PaCO2 from 51.7 ± 1.7 mmHg to 41.3 ± 1.7 mmHg.
O’Brien et al. [1999]	15	>45 mmHg	Decrease in PaCO2 from 59 ± 7 mmHg to 50 ± 9 mmHg. Improvement in pulmonary function. Improvement in exercise capacity. Improvement in quality of life.
Shade et al. [1999]	33		Decrease in PaCO2 from 44 ± 7 mmHg to 42 ± 5 mmHg. Improvement in pulmonary function.
Tsunezuka et al. [2000]	3	>50 mmHg	Decrease in PaCO2 from 52 ± 1 mmHg to 48 ± 2 mmHg.
Mitsui et al. [2001]	6	⩾60 mmHg	Decrease in PaCO2 from 70.4 ± 9.4 mmHg to 46.9 ± 3.4 mmHg. Improvement in pulmonary function.

HRF, hypercapnic respiratory failure; PaCO₂, partial pressure of carbon dioxide in arterial blood.