Effect of Carbogen Breathing and Acetazolamide on Optic Disc P<scp>o</scp><sub>2</sub>

Petropoulos, Ioannis K.; Pournaras, Jean-Antoine; Cruz, J.L.; Pournaras, Constantin J.

doi:10.1167/iovs.05-0258

Cited by 14 publications

(12 citation statements)

References 49 publications

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“…38,58 The effect of carbogen has not been studied here, because it involves complex and opposite effects of O 2 and CO 2 on the ocular vasculature, systemic effect on blood pressure, and a CO 2 -induced rightward shift of the oxyhemoglobin dissociation curve. 59 In contrast, our study demonstrates the significant effect of hypercapnia on ChBF. The 5% increase in ChBF is less than the reported 16% to 22% using interferometry 60 secondary to a 10 mm Hg PCO 2 increase.…”

Section: Bf Response To Hypercapniacontrasting

confidence: 85%

“…They involve metabolic intermediates such as nitric oxide in the retina, 62 the optic disc, 63 and the brain, 64 prostaglandins, 59,65 and a reduction in intracellular pH in retinal capillary pericytes. 61,66,67 The absence of effect of hypercapnia on ONHBF and ChBF could be related to the species difference regarding tissue-related vasoreactivity (in relationship to the size of vessels), the retinal arterioles being less sensitive to hypercapnia than cerebral arteries, 59,68 and the impact of hypercapnia on the orthosympathic system projecting on the choroid. 69,70 Range of BF Responses to Gas Inhalation Our healthy young subjects showed some heterogeneity in the magnitude of their responses to the changes in the blood gases.…”

Section: Bf Response To Hypercapniamentioning

confidence: 99%

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Hypoxic, Hypercapnic, and Hyperoxic Responses of the Optic Nerve Head and Subfoveal Choroid Blood Flow in Healthy Humans

Gallice

Zhou

Aptel

et al. 2017

Invest. Ophthalmol. Vis. Sci.

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Citation: Gallice M, Zhou T, Aptel F, et al. Hypoxic, hypercapnic, and hyperoxic responses of the optic nerve head and subfoveal choroid blood flow in healthy humans. Invest Ophthalmol Vis Sci. 2017;58:5460-5467. DOI:10.1167/iovs.17-21855 PURPOSE. To investigate the impact of different gas mixtures (hyperoxia, hypoxia, and hypercapnia) on the optic nerve head (ONH) and choroidal (Ch) hemodynamics.METHODS. Twenty-three healthy subjects (28 6 6 years) took part in the study. Variations in inspired oxygen and carbon dioxide fraction were produced by a gas mixing device. Arterial oxygen saturation (SpO 2 ) was measured continuously using a transcutaneous sensor and endtidal carbon dioxide partial pressure by capnography. The experiment comprised three successive periods: 3-minute baseline (room air breathing), 15-minute gas mixture inhalation (normocapnic hypoxia, hypercapnia, or hyperoxia), and 15-minute recovery (room air breathing). Laser Doppler flowmeter parameters-velocity (VEL), volume (VOL), and flow (BF) of red blood cells-were measured. Two-way ANOVAs were performed for statistical analysis.RESULTS. In response to hyperoxia, ONHBF significantly decreased by À18% 6 6% (P ¼ 0.04) from baseline, due to significant changes in VEL (À12% 6 3% P ¼ 0.0002). During hypoxia at 85% SpO 2, ONH VEL increased by þ12% 6 3% (P ¼ 0.0009), whereas VOL and BF did not change significantly. ChBF significantly increased by þ7% 6 2% (P ¼ 0.004) in response to hypoxia, due to significant changes in VEL þ5% 6 2% (P ¼ 0.03). Both Ch and ONHBFs did not vary significantly in response to hypercapnia.CONCLUSIONS. The magnitude of the blood flow response is the most significant during hyperoxia for ONH and hypoxia for ChBF. For ONHBF, a 37% difference between hyperoxia and hypoxia can be useful when vasoreactivity to O 2 will be tested in patients.

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Section: Bf Response To Hypercapniacontrasting

confidence: 85%

Section: Bf Response To Hypercapniamentioning

confidence: 99%

Hypoxic, Hypercapnic, and Hyperoxic Responses of the Optic Nerve Head and Subfoveal Choroid Blood Flow in Healthy Humans

Gallice

Zhou

Aptel

et al. 2017

Invest. Ophthalmol. Vis. Sci.

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“…Within recent years the use of pigs as an in vivo experimental model in ophthalmological posterior-segment research has increased (Garcia et al 2005;Kiilgaard et al 2005;Petropoulos et al 2005;Schmidt Laugesen et al 2005;Stefansson et al 2005;Tao et al 2005;Warfinge et al 2005;Iandiev et al 2006;Kwan et al 2006;Pedersen et al 2006;Salyer et al 2006). There are anatomical similarities between the human and the porcine eye, macroscopic as well as histological, making this animal a good model when testing ophthalmologic treatment modalities and surgical procedures.…”

Section: Introductionmentioning

confidence: 99%

The multifocal electroretinogram (mfERG) in the pig

Kyhn

Kiilgaard

López

et al. 2007

Acta Ophthalmologica Scandinavica

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ABSTRACT.Purpose: To establish a method allowing multifocal electroretinography (mfERG) recording with simultaneous fundus monitoring on anaesthetized pigs. In addition we characterize the peaks of the porcine mfERG trace, and compare the visual streak area with the optic nerve head, a known nonresponse area. Finally we illustrate the feasibility of the method by performing mfERG after an induced laser burn in the visual streak. Methods: Fifteen pigs underwent mfERG recordings at baseline, and after 1 and 6 weeks of observation. One pig was evaluated before and after retinal diode laser treatment in the visual streak. Results: The porcine mfERG trace appears similar to the human mfERG trace, and can be described by three peaks named N1, P1 and N2. Significantly faster implicit time was found in the visual streak regarding N1 (P < 0.001) than in areas outside the visual streak. Amplitudes of all three peaks were increased in the visual streak (P < 0.005). The laser-treated area was characterized by a response similar to what is found at the location of the optic nerve head. Conclusion: Porcine mfERG is similar in appearance to the human response and can be described by the same three peaks. Significantly higher amplitudes of all three peaks are found in the visual streak when compared to the optic nerve head and inferior retina. We have detected the functional deficit caused by a laser burn at the size of 3 · 3 mm.

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“…As retinal and ONH vessels are not sympathetically innervated, the mechanism that underlies their autoregulation system is the balanced result of myogenic and metabolic components that maintain constant blood flow during changes in PPm (Pournaras et al 2008). Having an animal or human subject breath various mixtures of gases can reveal the role of blood O 2 and CO 2 on the modulation of arterial and capillaries retinal and ONH blood flow regulation (Petropoulos et al 2005(Petropoulos et al , 2009Pournaras et al 2008).…”

Section: Regulation Of Blood Flow In Retina and Optic Nerve Head (Onh)mentioning

confidence: 99%

Vision impairment during cardiac surgery and extracorporeal circulation: current understanding and the need for further investigation

Nenekidis

Pournaras

Tsironi

et al. 2011

Acta Ophthalmologica

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Extracorporeal circulation (ECC) constitutes a supreme tool for heart surgery allowing the surgeon to work on a secure surgical field by bypassing the cardiopulmonary system. However, pathophysiological hemodynamic changes occur from the use of the heart-lung device that regulates the venous return, cardiac output and oxygenation of blood. This condition is well described as 'surgical hypothermic controlled shock', or in cases of severe hypothermia, the term 'total arrest' is used to denote the lowest level of preservation that the body tolerates with respect to its metabolic needs. Hemodynamic Changes During ECCSignificant changes in homoeostasis occur at the very beginning of ECC as systemic vasodilatation prevails in order to maintain proper blood flow within vital organs. Additionally, the administration of heparin potentiates this vasodilatory effect. Following the establishment of hypothermia (moderate hypothermia, down to 25°C, or severe hypothermia, down to 18°C), the peripheral resistance increases because of severe vasoconstriction. During this phase, the metabolic profile changes because of the decreased metabolic demands of the organism. In general, it is believed that at a temperature of 29-30°C within approximately 130 min of ECC, the energy loss is approximately 330 KJ in a 75-to 90-kg patient (Pacifico et al. 1970 ABSTRACT. The aim of this article was to provide a comprehensive review of current knowledge regarding ocular hemodynamic alterations affecting the retinal neuroglial cells and optic nerve head (ONH) function during cardiac surgery. Literature indicates that visual loss after heart surgery is a rare but devastating complication provoked by two main causes of optic ischaemia and infarction during on-pump cardiac procedures: microembolism and ⁄ or hypoperfusion.Retinal ischaemia and ischaemic optic neuropathy are two possible major consequences of extracorporeal circulation in cardiac surgery. The hemodynamic modifications within the vascular beds of retina and ONH during cardiovascular operations have been incompletely studied. Consequently, it is of great interest to investigate the hemodynamic changes during cardiopulmonary bypass within the choroidal, retinal and optic nerve microcirculations as well as other potential causes of vaso-occlusion. Maintaining stable hemodynamic parameters during cardiovascular surgery seems to be the key to prevent visual impairment.

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Effect of Carbogen Breathing and Acetazolamide on Optic Disc Po₂

Abstract: Carbogen breathing increases optic disc Po(2) significantly in minipigs, more than hyperoxia. The association of acetazolamide injection with carbogen breathing could induce an additional increase in optic disc PO(2) through the effect of higher systemic PaCO(2).

Cited by 14 publications

References 49 publications

Hypoxic, Hypercapnic, and Hyperoxic Responses of the Optic Nerve Head and Subfoveal Choroid Blood Flow in Healthy Humans

Hypoxic, Hypercapnic, and Hyperoxic Responses of the Optic Nerve Head and Subfoveal Choroid Blood Flow in Healthy Humans

The multifocal electroretinogram (mfERG) in the pig

Vision impairment during cardiac surgery and extracorporeal circulation: current understanding and the need for further investigation

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Effect of Carbogen Breathing and Acetazolamide on Optic Disc Po2

Abstract: Carbogen breathing increases optic disc Po(2) significantly in minipigs, more than hyperoxia. The association of acetazolamide injection with carbogen breathing could induce an additional increase in optic disc PO(2) through the effect of higher systemic PaCO(2).

Cited by 14 publications

References 49 publications

Hypoxic, Hypercapnic, and Hyperoxic Responses of the Optic Nerve Head and Subfoveal Choroid Blood Flow in Healthy Humans

Hypoxic, Hypercapnic, and Hyperoxic Responses of the Optic Nerve Head and Subfoveal Choroid Blood Flow in Healthy Humans

The multifocal electroretinogram (mfERG) in the pig

Vision impairment during cardiac surgery and extracorporeal circulation: current understanding and the need for further investigation

Contact Info

Product

Resources

About

Effect of Carbogen Breathing and Acetazolamide on Optic Disc Po₂