You will be provided with the titles and abstracts of a collection of medical RCT reports studying a clinical question -- for instance, the efficacy of an intervention on some medical outcome. Please write a few sentences synthesizing the findings of these reports, which could serve as a conclusion section for a systematic review article. Your response should not include any other text. The RCT reports are below.



Title 1:
Effects of chlormadinone acetate, acetazolamide and oxygen on awake and asleep gas exchange in patients with chronic obstructive pulmonary disease (COPD).
Abstract 1:
The purpose of this study was to assess the short-term effects of chlormadinone acetate (CMA), a synthetic progestogen, acetazolamide (ACET) and oxygen on awake and asleep blood gas values. The study was conducted according to a randomized, double-blind and placebo-controlled design in 53 hypoxaemic patients with chronic obstructive pulmonary disease. On the first two consecutive nights, all patients received either room air or oxygen, via a nasal cannula, in random order. They then received either CMA (25 mg), ACET (250 mg) or placebo twice a day, all in identical capsules. On the third study night, after one week of drug treatment, the patients were tested breathing room air. CMA and ACET therapy decreased mean daytime arterial carbon dioxide tension (PaCO2) by 0.7 and 0.5 kPa, respectively, and night-time end-tidal carbon dioxide tension (PETCO2) by 0.5 and 0.3 kPa, respectively. Supplemental oxygen caused increased CO2 retention during the day and night (0.6 and 0.3 kPa, respectively. Daytime arterial oxygen tension (PaO2) increased to the same extent during ACET (1.9 kPa) and oxygen (2.5 kPa). Asleep oxygen saturation improved most with oxygen supplementation (7%), although ACET also caused significant improvement (4%). CMA administration had virtually no effect on mean awake and asleep hypoxaemia. ACET therapy significantly improved subjective sleep quality. On CMA, minute ventilation increased in association with an augmentation of the hypercapnic ventilatory response. ACET treatment increased both hypercapnic and hypoxic ventilatory responses. We conclude from the group of patients with COPD studied, that the short-term effects of ACET treatment on gas exchange compare favourably with those of CMA. Oxygen therapy improves oxygenation slightly more than ACET, but aggravates CO2 retention.


Title 2:
Comparison of acetazolamide and medroxyprogesterone as respiratory stimulants in hypercapnic patients with COPD.
Abstract 2:
Acetazolamide and medroxyprogesterone acetate (MPA) are two respiratory stimulants that can be used in patients with stable hypercapnic COPD.
                The effects of acetazolamide, 250 mg bid, and MPA, 30 mg bid, on daytime and nighttime blood gas values and the influences on the hypercapnic and hypoxic ventilatory and mouth occlusion pressure (P(0.1)) at 100 ms response were studied in a crossover design in 12 hypercapnic patients with stable COPD (FEV(1), 33 +/- 4% predicted [mean +/- SEM]).
                Daytime PaCO(2) decreased from 47.3 +/- 0.8 mm Hg (placebo) to 42.0 +/- 1.5 mm Hg during acetazolamide treatment (p < 0.05) and to 42.8 +/- 1.5 mm Hg during MPA treatment (p < 0.05). Daytime PaO(2) improved with acetazolamide from 65.2 +/- 2.3 to 75.0 +/- 3.0 mm Hg (p < 0.05), whereas no significant changes were seen with MPA. Mean nocturnal end-tidal carbon dioxide tension decreased with both treatments, from 42.0 +/- 2.3 to 35.3 +/- 2.3 mm Hg with acetazolamide (p < 0.05) and to 34.5 +/- 0.8 mm Hg with MPA (p < 0.05). The percentage of time that the nocturnal arterial oxygen saturation was < 90% was reduced significantly with acetazolamide, from 34.9 +/- 10.7% to 16.3 +/- 7.5% (p < 0.05). Mean nocturnal saturation did not change with MPA. Resting minute ventilation increased significantly only with MPA from 9.6 +/- 0.7 to 10.8 +/- 0.8 L/min (p < 0.05). The slope of the hypercapnic ventilatory response did not change during acetazolamide and MPA therapy. The hypoxic ventilatory response increased from - 0.2 +/- 0.05 to - 0.4 +/- 0.1 L/min/% during acetazolamide (p < 0.05) and to - 0.3 +/- 0.1 L/min/% during MPA (p < 0.05). The hypoxic P(0.1) response improved with acetazolamide treatment from - 0.05 +/- 0.008 to - 0.15 +/- 0.02 mm Hg/% (p < 0.05).
                This study shows that acetazolamide and MPA both have favorable effects on daytime and nighttime blood gas parameters in ventilatory-limited patients with stable COPD. However, the use of acetazolamide is preferred because of its extra effect on nocturnal saturation.


Title 3:
Relative effectiveness of acetazolamide versus medroxyprogesterone acetate in correction of chronic carbon dioxide retention.
Abstract 3:
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Acetazolamide can produce a small increase in arterial PO2 and fall in PCO2. These conclusions are drawn from a few small short studies that were not all of high quality. It is not known whether this physiological improvement is associated with clinical benefit.