Study: NCT02990078

Intervention type: DRUG
Intervention: Sildenafil citrate
Description: Sildenafil is a potent and specific PDE5 inhibitor, which was initially developed for the treatment of hypertension and angina. Its effectiveness as a treatment for male erectile dysfunction became apparent during Phase I clinical trials, and the focus of drug development shifted to this indication. In patients with cerebrovascular dysfunction, a few preliminary studies have used sildenafil to increase CVR. Participants in the pilot study had CVR tested in response to hypercapnia measured twice, at baseline and then 1 hour after administration of sildenafil citrate, 50 mg by mouth. The investigators have an IND exemption for the uses in this study.

Intervention type: DRUG
Intervention: Sildenafil citrate
Description: Sildenafil is a potent and specific PDE5 inhibitor, which was initially developed for the treatment of hypertension and angina. Its effectiveness as a treatment for male erectile dysfunction became apparent during Phase I clinical trials, and the focus of drug development shifted to this indication. In patients with cerebrovascular dysfunction, a few preliminary studies have used sildenafil to increase CVR. Participants in the pilot study had CVR tested in response to hypercapnia measured twice, at baseline and then 1 hour after administration of sildenafil citrate, 50 mg by mouth. The investigators have an IND exemption for the uses in this study.

Intervention type: DRUG
Intervention: Sildenafil citrate
Description: Sildenafil is a potent and specific PDE5 inhibitor, which was initially developed for the treatment of hypertension and angina. Its effectiveness as a treatment for male erectile dysfunction became apparent during Phase I clinical trials, and the focus of drug development shifted to this indication. In patients with cerebrovascular dysfunction, a few preliminary studies have used sildenafil to increase CVR. Participants in the pilot study had CVR tested in response to hypercapnia measured twice, at baseline and then 1 hour after administration of sildenafil citrate, 50 mg by mouth. The investigators have an IND exemption for the uses in this study.

Intervention type: DEVICE
Intervention: Functional Near Infared Spectroscopy
Description: Functional near-infrared spectroscopy (fNIRS) will be used to measure regional cerebral blood flow and cerebrovascular reactivity. are connected to the scalp and surrounding detectors a few cm away detect the light as it scatters through the underlying tissues. The technique is able to detect changes in the absorption spectrum of the tissue corresponding to the concentrations of oxyhemoglobin (HbO2) and deoxyhemoglobin (HbR), and indicate local perfusion changes.

Intervention type: DEVICE
Intervention: Functional Near Infared Spectroscopy
Description: Functional near-infrared spectroscopy (fNIRS) will be used to measure regional cerebral blood flow and cerebrovascular reactivity. are connected to the scalp and surrounding detectors a few cm away detect the light as it scatters through the underlying tissues. The technique is able to detect changes in the absorption spectrum of the tissue corresponding to the concentrations of oxyhemoglobin (HbO2) and deoxyhemoglobin (HbR), and indicate local perfusion changes.

Intervention type: DEVICE
Intervention: Functional Near Infared Spectroscopy
Description: Functional near-infrared spectroscopy (fNIRS) will be used to measure regional cerebral blood flow and cerebrovascular reactivity. are connected to the scalp and surrounding detectors a few cm away detect the light as it scatters through the underlying tissues. The technique is able to detect changes in the absorption spectrum of the tissue corresponding to the concentrations of oxyhemoglobin (HbO2) and deoxyhemoglobin (HbR), and indicate local perfusion changes.

Intervention type: OTHER
Intervention: Hypercapnia Challenge
Description: The study device is a Douglas Bag that traditionally is designed to measure respiratory exchange. It consists of large bag attached to a mouthpiece utilized to hold either expired air from the subject or filled with different concentrations of air to be aspired. For the purposes of this study, the Douglas Bag will be utilized to induce hypercapnia in the subject. The bag is equipped with a switch that allows rapid shifting from room air to 5% CO2 each minute over 7 minutes.

Intervention type: OTHER
Intervention: Hypercapnia Challenge
Description: The study device is a Douglas Bag that traditionally is designed to measure respiratory exchange. It consists of large bag attached to a mouthpiece utilized to hold either expired air from the subject or filled with different concentrations of air to be aspired. For the purposes of this study, the Douglas Bag will be utilized to induce hypercapnia in the subject. The bag is equipped with a switch that allows rapid shifting from room air to 5% CO2 each minute over 7 minutes.

Intervention type: OTHER
Intervention: Hypercapnia Challenge
Description: The study device is a Douglas Bag that traditionally is designed to measure respiratory exchange. It consists of large bag attached to a mouthpiece utilized to hold either expired air from the subject or filled with different concentrations of air to be aspired. For the purposes of this study, the Douglas Bag will be utilized to induce hypercapnia in the subject. The bag is equipped with a switch that allows rapid shifting from room air to 5% CO2 each minute over 7 minutes.