RATIONALE: Impaired endothelium-dependent vasodilation has been documented in patients with sleep apnea. This impairment may result in blood flow dysregulation during apnea-induced fluctuations in arterial blood gases. OBJECTIVES: To test the hypothesis that hypoxic and hypercapnic vasodilation in the forearm and cerebral circulation are impaired in patients with sleep apnea. METHODS: We exposed 20 patients with moderate to severe sleep apnea and 20 control subjects, to isocapnic hypoxia and hyperoxic hypercapnia. A subset of 14 patients was restudied after treatment with continuous positive airway pressure. MEASUREMENTS AND MAIN RESULTS: Cerebral flow velocity (transcranial Doppler), forearm blood flow (venous occlusion plethysmography), arterial pressure (automated sphygmomanometry), oxygen saturation (pulse oximetry), ventilation (pneumotachograph), and end-tidal oxygen and carbon dioxide tensions (expired gas analysis) were measured during three levels of hypoxia and two levels of hypercapnia. Cerebral vasodilator responses to hypoxia (-0.65 +/- 0.44 vs. -1.02 +/- 0.72 [mean +/- SD] units/% saturation; P = 0.03) and hypercapnia (2.01 +/- 0.88 vs. 2.57 +/- 0.89 units/mm Hg; P = 0.03) were smaller in patients versus control subjects. Hypoxic vasodilation in the forearm was also attenuated (-0.05 +/- 0.09 vs. -0.10 +/- 0.09 unit/% saturation; P = 0.04). Hypercapnia did not elicit forearm vasodilation in either group. Twelve weeks of continuous positive airway pressure treatment enhanced hypoxic vasodilation in the cerebral circulation (-0.83 +/- 0.32 vs. -0.46 +/- 0.29 units/% saturation; P = 0.01) and forearm (-0.19 +/- 0.15 vs. -0.02 +/- 0.08 units/% saturation; P = 0.003), and hypercapnic vasodilation in the brain showed a trend toward improvement (2.24 +/- 0.78 vs. 1.76 +/- 0.64 units/mm Hg; P = 0.06). CONCLUSIONS: Vasodilator responses to chemical stimuli in the cerebral circulation and the forearm are impaired in many patients with obstructive sleep apnea. Some of these impairments can be improved with continuous positive airway pressure.
RATIONALE: Impaired endothelium-dependent vasodilation has been documented in patients with sleep apnea. This impairment may result in blood flow dysregulation during apnea-induced fluctuations in arterial blood gases. OBJECTIVES: To test the hypothesis that hypoxic and hypercapnic vasodilation in the forearm and cerebral circulation are impaired in patients with sleep apnea. METHODS: We exposed 20 patients with moderate to severe sleep apnea and 20 control subjects, to isocapnic hypoxia and hyperoxic hypercapnia. A subset of 14 patients was restudied after treatment with continuous positive airway pressure. MEASUREMENTS AND MAIN RESULTS: Cerebral flow velocity (transcranial Doppler), forearm blood flow (venous occlusion plethysmography), arterial pressure (automated sphygmomanometry), oxygen saturation (pulse oximetry), ventilation (pneumotachograph), and end-tidal oxygen and carbon dioxide tensions (expired gas analysis) were measured during three levels of hypoxia and two levels of hypercapnia. Cerebral vasodilator responses to hypoxia (-0.65 +/- 0.44 vs. -1.02 +/- 0.72 [mean +/- SD] units/% saturation; P = 0.03) and hypercapnia (2.01 +/- 0.88 vs. 2.57 +/- 0.89 units/mm Hg; P = 0.03) were smaller in patients versus control subjects. Hypoxic vasodilation in the forearm was also attenuated (-0.05 +/- 0.09 vs. -0.10 +/- 0.09 unit/% saturation; P = 0.04). Hypercapnia did not elicit forearm vasodilation in either group. Twelve weeks of continuous positive airway pressure treatment enhanced hypoxic vasodilation in the cerebral circulation (-0.83 +/- 0.32 vs. -0.46 +/- 0.29 units/% saturation; P = 0.01) and forearm (-0.19 +/- 0.15 vs. -0.02 +/- 0.08 units/% saturation; P = 0.003), and hypercapnic vasodilation in the brain showed a trend toward improvement (2.24 +/- 0.78 vs. 1.76 +/- 0.64 units/mm Hg; P = 0.06). CONCLUSIONS: Vasodilator responses to chemical stimuli in the cerebral circulation and the forearm are impaired in many patients with obstructive sleep apnea. Some of these impairments can be improved with continuous positive airway pressure.
Authors: Virginia A Imadojemu; Kevin Gleeson; Sadeq A Quraishi; Allen R Kunselman; Lawrence I Sinoway; Urs A Leuenberger Journal: Am J Respir Crit Care Med Date: 2002-04-01 Impact factor: 21.405
Authors: R Schulz; S Mahmoudi; K Hattar; U Sibelius; H Olschewski; K Mayer; W Seeger; F Grimminger Journal: Am J Respir Crit Care Med Date: 2000-08 Impact factor: 21.405
Authors: Tadeusz Przybyłowski; Muhammad-Fuad Bangash; Kevin Reichmuth; Barbara J Morgan; James B Skatrud; Jerome A Dempsey Journal: J Physiol Date: 2003-02-14 Impact factor: 5.182
Authors: Jefferson C Frisbee; Kristopher G Maier; John R Falck; Richard J Roman; Julian H Lombard Journal: Am J Physiol Regul Integr Comp Physiol Date: 2002-08 Impact factor: 3.619
Authors: F Javier Nieto; David M Herrington; Susan Redline; Emelia J Benjamin; John A Robbins Journal: Am J Respir Crit Care Med Date: 2003-10-09 Impact factor: 21.405
Authors: M Kato; P Roberts-Thomson; B G Phillips; W G Haynes; M Winnicki; V Accurso; V K Somers Journal: Circulation Date: 2000-11-21 Impact factor: 39.918
Authors: Lindsay S Cahill; Lisa M Gazdzinski; Albert Ky Tsui; Yu-Qing Zhou; Sharon Portnoy; Elaine Liu; C David Mazer; Gregory Mt Hare; Andrea Kassner; John G Sled Journal: J Cereb Blood Flow Metab Date: 2016-07-20 Impact factor: 6.200
Authors: J Mikhail Kellawan; John W Harrell; Alejandro Roldan-Alzate; Oliver Wieben; William G Schrage Journal: J Cereb Blood Flow Metab Date: 2016-01-01 Impact factor: 6.200
Authors: Jacqueline K Limberg; Trent D Evans; Gregory M Blain; David F Pegelow; Jessica R Danielson; Marlowe W Eldridge; Lester T Proctor; Joshua J Sebranek; William G Schrage Journal: Eur J Appl Physiol Date: 2011-06-09 Impact factor: 3.078
Authors: Igor A Fernandes; Marcos P Rocha; Monique O Campos; João D Mattos; Daniel E Mansur; Helena N M Rocha; Paulo A C Terra; Vinícius P Garcia; Natália G Rocha; Niels H Secher; Antonio C L Nóbrega Journal: J Physiol Date: 2018-02-28 Impact factor: 5.182
Authors: Barbara J Morgan; Mihaela Teodorescu; David F Pegelow; Emily R Jackson; Devin L Schneider; David T Plante; James P Gapinski; Scott J Hetzel; John M Dopp Journal: Exp Physiol Date: 2018-06-08 Impact factor: 2.969