Trial reportEuropean journal of applied physiology2009
The effects of sildenafil and acetazolamide on breathing efficiency and ventilatory control during hypoxic exercise.
Trial report in European journal of applied physiology, 2009. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 14 papers, 6 of them syntheses that pooled it.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
14 citing papers in PubMed, 6 syntheses or guidelines pooled it, 21 citations in OpenAlex.
- Side effects of acetazolamide: a systematic review and meta-analysis assessing overall risk and dose dependence.BMJ open respiratory research · 2020Pooled it
- Interventions for preventing high altitude illness: Part 3. Miscellaneous and non-pharmacological interventions.The Cochrane database of systematic reviews · 2019Pooled it
- Sildenafil does not reliably improve exercise performance in hypoxia: a systematic review.BMJ open sport & exercise medicine · 2019Pooled it
- Interventions for preventing high altitude illness: Part 2. Less commonly-used drugs.The Cochrane database of systematic reviews · 2018Pooled it
- Interventions for preventing high altitude illness: Part 1. Commonly-used classes of drugs.The Cochrane database of systematic reviews · 2017Pooled it
- Phosphodiesterase type 5 inhibitors for high-altitude pulmonary hypertension: a meta-analysis.Clinical drug investigation · 2010Pooled it
- Sildenafil therapy in thalassemia patients with Doppler-defined risk of pulmonary hypertension.Haematologica · 2013Trial
- Case Report: High altitude, young lives: unmasking pulmonary hypertension in two unique cases.Frontiers in medicine · 2025Article
- Efficacy of Sildenafil on healthy humans in high‑altitude hypoxia at rest and during exercise: A meta‑analysis.Experimental and therapeutic medicine · 2024Article
- Decreased Work Capability Related to High-Altitude Exposure.Risk management and healthcare policy · 2024Review
- Three novel prevention, diagnostic, and treatment options for COVID-19 urgently necessitating controlled randomized trials.Medical hypotheses · 2020Article
- Systematic Review of the Effects of Phosphodiesterase-5 Inhibitors and Dexamethasone on High Altitude Pulmonary Edema (HAPE).Spartan medical research journal · 2019Review
- Ventilatory oscillations at exercise: effects of hyperoxia, hypercapnia, and acetazolamide.Physiological reports · 2015Article
- New insights into carbonic anhydrase inhibition, vasodilation, and treatment of hypertensive-related diseases.Current hypertension reports · 2014Review
Corrections and comments
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Authors and funding
8 authors at 3 institutions in 1 country.
Funding
Abstract
The reduced arterial oxygen tension at high altitude impairs the ability to work. Acetazolamide improves arterial oxygen saturation (SaO(2)) by increasing ventilation but is associated with an increased work and cost of breathing. Depending on the settings, sildenafil can also increases SaO(2) possibly through a reduction in pulmonary hypertension and interstitial edema, which could improve ventilation-perfusion matching. The objective of this study is to determine the effects of acetazolamide and sildenafil on ventilatory control and breathing efficiency (V(E)/VCO(2)) during submaximal steady-state hypoxic exercise in healthy individuals. Following 18 h of hypoxic exposure in an altitude tent at an oxygen concentration of 12.5% (simulated altitude of 4,300 m), 15 participants performed 10 min of hypoxic exercise on a stationary bicycle at 40% of their sea level peak oxygen uptake (VO(2)) while randomly receiving sildenafil 40 mg (SIL), acetazolamide 125 mg (ACZ) or a placebo (PLA). There was no difference in VO(2) during exercise between conditions while SaO(2) was greater with acetazolamide compared to both placebo and sildenafil. Acetazolamide increased ventilation (PLA 49.0 +/- 3.2, SIL 47.7 +/- 3.1, ACZ 52.1 +/- 3.0 l/min) and reduced end-tidal CO(2) (P(ET)CO(2)) (PLA 32.1 +/- 0.8, SIL 32.8 +/- 0.9, ACZ 29.2 +/- 0.7 mmHg) compared to placebo and sildenafil. Breathing was less efficient with acetazolamide (increased V(E)/VCO(2)) in comparison to placebo and sildenafil (PLA 41.5 +/- 1.0, SIL 40.4 +/- 1.3, ACZ 45.4 +/- 1.0) while sildenafil did not change V(E)/VCO(2) during hypoxic exercise. In conclusion, acetazolamide increased ventilation and reduced breathing efficiency while sildenafil did not affect breathing efficiency despite a trend toward a blunted ventilatory response, possibly due to a reduction in pulmonary hypertension and/or ventilatory drive, during submaximal hypoxic exercise in healthy individuals.
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