Active clinical trials for "Hypocapnia"

Postural tachycardia syndrome (POTS) is the most common chronic cause of postural lightheadedness, and upright confusion afflicting many Americans, mostly young women. Many POTS patients hyperventilate by increasing their depth of breathing that produces tachycardia, alters blood flow and blood pooling in the body and importantly reduces brain blood flow causing "brain fog". In this proposal the investigators will demonstrate in young women that abnormal repeated brief impairment of blood pressure and brain flow just after standing sensitizes the body's oxygen sensor in POTS to respond as if it were in a low oxygen environment causing hyperventilation and its consequences. In this project the investigators will use various drugs that will help to understand the mechanisms that cause POTS in this unique subset of POTS patients who hyperventilate.

The purpose of this research study is to better understand how blood flow and metabolism are different between normal controls and patients with disease. The investigators will examine brain blood flow and metabolism using magnetic resonance imaging (MRI). The brain's blood vessels expand and constrict to regulate blood flow based on the brain's needs. The amount of expanding and contracting the blood vessels can do varies by age. The brain's blood flow changes in small ways during everyday activities, such as normal brain growth, exercise, or deep concentration. Significant illness or physiologic stress may increase the brain's metabolic demand or cause other bigger changes in blood flow. If blood vessels are not able to expand to give more blood flow when metabolic demand is high, the brain may not get all of the oxygen it needs. In less extreme circumstances, not having as much oxygen as it wants may cause the brain to grow and develop more slowly than it should. One way to test the ability of the blood vessels to expand is by measuring blood flow while breathing in carbon dioxide (CO2). CO2 causes blood vessels in the brain to dilate without increasing brain metabolism. The study team will use a special mask to control the amount of oxygen and carbon dioxide patients breath in so that we can study how their brain reacts to these changes. This device designed to simulate carbon dioxide levels achieved by a breath-hold and target the concentration of carbon dioxide in the blood in breathing patients. The device captures exhaled gas and provides an admixture of fresh gas and neutral/expired gas to target different carbon dioxide levels while maintaining a fixed oxygen level. The study team will obtain MRI images of the brain while the subjects are breathing air controlled by the device.

This is a Phase I, open-label, single center trial to evaluate the feasibility and safety of low concentration CO2 gas mixture (5% CO2 + 95% air) inhalation in asphyxiated, cooled, mechanically ventilated newborns at risk of hypocapnia with The hypothesis is that hypocapnia, which is driven by hyperventilation in the presence of metabolic acidosis, is deleterious to the injured brain and can be safely avoided with low concentration CO2 inhalation.

Abdominal surgery commonly requires perioperative relaxation and therefore controlled mechanical ventilation. However, respiratory support can be associated with minor, yet clinically significant changes in blood gas content. The inadvertent hyperoxia (excessively high oxygen) and/or hypocapnia (excessively low carbon dioxide) can result in transient changes in cerebral blood flow and cognitive impair.

This research study is being done to evaluate the effectiveness of using the sharpened Romberg test to screen for impaired postural control in patients with impaired or altered breathing patterns.

Hyper Ventilation Syndrome is a frequent disease affecting adults whose diagnosis is often belated or even unrecognized due to the lack of "gold standard" criteria. Its diagnosis currently relies on the Nijmegen score associated with a PetCO2 assesment using a hyperventilation provocation test. Correlation between Nijmegen Questionnaire scores and PetCO2 appears highly variable. PtcCO2 monitoring is a noninvasive alternative method providing a continuous estimation of arterial CO2 pressure (PaCO2) which could represent an advantageous alternative to PetCO2 measurements. Several reports have demonstrated that PtcCO2 monitoring reflects more faithfully PaCO2 than PetCO2, no study have evaluated its value in this indication. The primary aim of the study is to compare the diagnostic value of PtcPCO2 monitoring with PetCO2, the method currently used. Included patient will be invited to fill in the Nijmegen questionnaire and an ambient air gas measurement will be performed. PtcCO2 (mmHg) will be simultaneously measured during hyperventilation test. Nijmegen score signs reproduced by the test will be analysed. HVS diagnosis will be assessed by usual criteria (PetCO2 <30 mmHg at the end of hyperventilation test or under the PetCO2 value at rest, Nijmegen score> 23). PtcCO2 data will be blinded interpreted later. We will compare if PetCO2 and PtcCO2 leads to the same diagnosis or not.

To gain a better understanding of the epidemiology of intraoperative hypocapnia, in particular the associations of intraoperative hypocapnia with patient demographics, ventilator characteristics, and perioperative complications we will perform an individual patient-level meta-analysis of two recent randomized clinical trials of intraoperative ventilation, the 'PROtective Ventilation using High versus LOw PEEP trial' (PROVHILO), and the 'Protective intraoperative ventilation with higher versus lower levels of positive end-expiratory pressure in obese patients trial' (PROBESE).

Assessment of Spry Health's Loop oximetry accuracy in profound hypoxia Assessment of Spry Health's Respiratory rate accuracy in normal conditions and profound hypoxia