Silvia Ulrich1, Yvonne Nussbaumer-Ochsner1, Irena Vasic1, Elisabeth Hasler1, Tsogyal D Latshang1, Malcolm Kohler2, Thomas Muehlemann3, Martin Wolf3, Konrad E Bloch4. 1. Pulmonary Division and Sleep Disorders Centre, University Hospital Zurich, Zurich, Switzerland. 2. Pulmonary Division and Sleep Disorders Centre, University Hospital Zurich, Zurich, Switzerland; Zurich Centre for Human Integrative Physiology and Zurich Centre for Interdisciplinary Sleep Research, University of Zurich, Zurich, Switzerland. 3. Biomedical Optics Research Laboratory, Division of Neonatology, University Hospital Zurich, Zurich, Switzerland. 4. Pulmonary Division and Sleep Disorders Centre, University Hospital Zurich, Zurich, Switzerland; Zurich Centre for Human Integrative Physiology and Zurich Centre for Interdisciplinary Sleep Research, University of Zurich, Zurich, Switzerland. Electronic address: konrad.bloch@usz.ch.
Abstract
BACKGROUND:Sleep-disordered breathing may impair cerebral oxygenation in patients with OSA syndrome, in particular during altitude travel. We studied cerebral tissue oxygenation (CTO) at low and moderate altitude in patients with OSA and evaluated whether acetazolamide improved CTO. METHODS:Eighteen patients with OSA living at < 600 m discontinued CPAP therapy during studies in Zurich (490 m) and during two sojourns of 3 days in the Swiss Alps (2 days at 1,860 m and 1 day at 2,590 m) separated by a 2-week washout period at < 600 m. Patients received acetazolamide (2 × 250 mg/d) or placebo at altitude in a randomized, double-blind, crossover design. Nocturnal polysomnography, including CTO monitoring by near-infrared spectroscopy (NIRS), was performed. RESULTS: At 490 m, medians of CTO, peripheral oxygen saturation as measured by pulse oximetry (Spo2), and apnea/hypopnea index were 65%, 93%, and 57.3/h, respectively. At 2,590 m, on placebo, the corresponding values were 59%, 86%, and 86.4/h, respectively (P < .05, all corresponding comparisons). Acetazolamide increased CTO and Spo2 at 2,590 m by mean values of 2% (95% CI, 0%-4%) and 2% (95% CI, 1%-3%), respectively, and reduced the apnea/hypopnea index by 23.4/h (95% CI, 14.0-32.8/h) (P < .05, all changes). Cerebral total hemoglobin concentration, a NIRS-derived surrogate reflecting regional cerebral blood volume, increased by a similar degree in response to apneas at 490 m and 2,590 m and during acetazolamide and placebo treatment. CONCLUSIONS: In patients with OSA staying at altitude, nocturnal cerebral and arterial oxygenation were reduced in association with exacerbated sleep apnea. Acetazolamide partially improved CTO, Spo2, and sleep apnea without impairing the cerebral blood flow response to apneas. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT00714740; URL: www.clinicaltrials.gov.
RCT Entities:
BACKGROUND:Sleep-disordered breathing may impair cerebral oxygenation in patients with OSA syndrome, in particular during altitude travel. We studied cerebral tissue oxygenation (CTO) at low and moderate altitude in patients with OSA and evaluated whether acetazolamide improved CTO. METHODS: Eighteen patients with OSA living at < 600 m discontinued CPAP therapy during studies in Zurich (490 m) and during two sojourns of 3 days in the Swiss Alps (2 days at 1,860 m and 1 day at 2,590 m) separated by a 2-week washout period at < 600 m. Patients received acetazolamide (2 × 250 mg/d) or placebo at altitude in a randomized, double-blind, crossover design. Nocturnal polysomnography, including CTO monitoring by near-infrared spectroscopy (NIRS), was performed. RESULTS: At 490 m, medians of CTO, peripheral oxygen saturation as measured by pulse oximetry (Spo2), and apnea/hypopnea index were 65%, 93%, and 57.3/h, respectively. At 2,590 m, on placebo, the corresponding values were 59%, 86%, and 86.4/h, respectively (P < .05, all corresponding comparisons). Acetazolamide increased CTO and Spo2 at 2,590 m by mean values of 2% (95% CI, 0%-4%) and 2% (95% CI, 1%-3%), respectively, and reduced the apnea/hypopnea index by 23.4/h (95% CI, 14.0-32.8/h) (P < .05, all changes). Cerebral total hemoglobin concentration, a NIRS-derived surrogate reflecting regional cerebral blood volume, increased by a similar degree in response to apneas at 490 m and 2,590 m and during acetazolamide and placebo treatment. CONCLUSIONS: In patients with OSA staying at altitude, nocturnal cerebral and arterial oxygenation were reduced in association with exacerbated sleep apnea. Acetazolamide partially improved CTO, Spo2, and sleep apnea without impairing the cerebral blood flow response to apneas. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT00714740; URL: www.clinicaltrials.gov.