Hypoxic vasoconstriction

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Spreading depolarizations (SDs) are a marker of brain injury and have a causative effect on ischemic lesion progression. The hemodynamic responses elicited by SDs are contingent upon the metabolic integrity of the affected tissue, with vasoconstrictive reactions leading to pronounced hypoxia often indicating poor outcomes. The stratification of hemodynamic responses within different cortical layers remains poorly characterized. This pilot study sought to elucidate the depth-specific hemodynamic changes in response to SDs within the gray matter of the gyrencephalic swine brain...

Retinopathy of prematurity (ROP) is a rare proliferative ocular condition that can happen in premature babies (born preterm <36 weeks) or who weigh <1.5 kg at birth (low birth weight babies). ROP is a major cause of childhood blindness. It is a premature disease since retina vascularization is completed only by 40 weeks of life. The survivability for preterm infants has increased owing to recent improvements in neonatal care during the past decade. As a result, the prevalence of ROP has risen concurrently...

Background One-lung ventilation (OLV) is a common ventilation technique used during thoracic surgery. It can cause serious complications in children, and hypoxic pulmonary vasoconstriction (HPV) is a protective mechanism against the resulting hypoxia. Dexmedetomidine does not affect HPV, so we will investigate its impact on the partial pressure of oxygen in arterial blood (PaO2) and pulmonary shunt fraction (Qs/Qt). Methods Children who underwent OLV were divided into two equal groups. The Dex group received 0...

Necrotizing enterocolitis (NEC) is a common gastrointestinal complication in premature infants, resulting in high morbidity and mortality, and its early detection is crucial for accurate treatment and outcome prediction. Extensive research has demonstrated a clear correlation between NEC and extremely low birth weight, degree of preterm, formula feeding, infection, hypoxic/ischemic damage, and intestinal dysbiosis. The development of noninvasive biomarkers of NEC from stool, urine, and serum has attracted a great deal of interest because to these clinical connections and the quest for a deeper knowledge of disease pathophysiology...

INTRODUCTION: Hypoxic pulmonary vasoconstriction (HPV) can be a challenging clinical problem. It is not fully elucidated where in the circulation the regulation of resistance takes place. It is often referred to as if it is in the arteries, but we hypothesized that it is in the venous side of the pulmonary circulation. METHODS: In an open thorax model, pigs were treated with a veno-venous extra corporeal membrane oxygenator to either oxygenate or deoxygenate blood passing through the pulmonary vessels...

Underwater activities are characterized by an imbalance between reactive oxygen/nitrogen species (RONS) and antioxidant mechanisms, which can be associated with an inflammatory response, depending on O2 availability. This review explores the oxidative stress mechanisms and related inflammation status (Oxy-Inflammation) in underwater activities such as breath-hold (BH) diving, Self-Contained Underwater Breathing Apparatus (SCUBA) and Closed-Circuit Rebreather (CCR) diving, and saturation diving. Divers are exposed to hypoxic and hyperoxic conditions, amplified by environmental conditions, hyperbaric pressure, cold water, different types of breathing gases, and air/non-air mixtures...

BACKGROUND: Congenital central hypoventilation syndrome (CCHS) is a life-threatening disorder of autonomic respiratory control. Mutations in the paired-like homeobox 2B (PHOX2B) gene impair respiratory drive, causing hypercarbia and hypoxaemia. Most patients with CCHS are diagnosed in the neonatal period; however, a few are diagnosed in adulthood. CASE SUMMARY: We report a 32-year-old man with a history of unexplained cyanosis 14 days after birth. He presented to our hospital with breathlessness and abnormal electrocardiogram findings discovered in a health check-up...

Recently, nanotechnology-based drug delivery platforms in treating pulmonary arterial hypertension (PAH) have gradually emerged. However, large mechanical stress and shear stress in blood vessels greatly affect the retention of nanopreparative materials at lesion sites, severely limiting nanotechnology-based drug delivery. Herein, a stimuli-responsive nanocraft was rationally designed by actively anchoring E-selectin overexpressed on pulmonary arterial endothelial cells (PAECs), under hypoxic conditions, allowing effective accumulation and retention of the drug at the lesion site...

Ventilation-perfusion matching occurs passively and is also actively regulated through hypoxic pulmonary vasoconstriction (HPV). The extent of HPV activity in humans, particularly normal subjects is uncertain. Current evaluation of HPV assesses changes in ventilation-perfusion relationships/pulmonary vascular resistance with hypoxia and are invasive, or unsuitable for patients because of safety concerns. We used a non-invasive imaging-based approach to quantify the pulmonary vascular response to oxygen as a metric of HPV by measuring perfusion changes between breathing 21% and 30%O2 using arterial spin labeling (ASL) MRI...

BACKGROUND: Neutrophil infiltration and hypoxic pulmonary vasoconstriction induced by hypobaric hypoxic stress are vital in high-altitude pulmonary edema (HAPE). Myeloperoxidase (MPO), an important enzyme in neutrophils, is associated with inflammation and oxidative stress and is also involved in the regulation of nitric oxide synthase (NOS), an enzyme that catalyzes the production of the vasodilatory factor nitric oxide (NO). However, the role of neutrophil MPO in HAPE's progression is still uncertain...

Maximal exercise capacity is reduced at altitude or during hypoxia at sea level. It has been suggested that this might reflect increased right ventricular afterload due to hypoxic pulmonary vasoconstriction. We have shown previously that the pulmonary vascular sensitivity to hypoxia is enhanced by sustained isocapnic hypoxia, and inhibited by intravenous iron. In this study, we tested the hypothesis that elevated pulmonary artery pressure contributes to exercise limitation during acute hypoxia. Twelve healthy volunteers performed incremental exercise tests to exhaustion breathing 12% oxygen, before and after sustained (8-h) isocapnic hypoxia at sea level...

We present a case of reverse McConnell's sign, a rare echocardiographic finding of right ventricular apical hypokinesis and basal hyperkinesis, in a patient with acute respiratory distress syndrome and septic shock. Although multiple etiologies were hypothesized, providers attributed this cardiomyopathy to increased right heart afterload from hypoxic pulmonary vasoconstriction. Cardiac function normalized as the patient's respiratory failure and sepsis resolved. This study highlights the value of early echocardiography to help guide management in critical illness...

Preterm infants with bronchopulmonary dysplasia (BPD) are prone to develop pulmonary hypertension (PH). Strong laboratory and clinical data suggest that antenatal factors, such as preeclampsia, chorioamnionitis, oligohydramnios, and placental dysfunction leading to fetal growth restriction, increase susceptibility for BPD-PH after premature birth. Echocardiogram metrics and serial assessments of NT-proBNP provide useful tools to diagnose and monitor clinical course during the management of BPD-PH, as well as monitoring for such complicating conditions as left ventricular diastolic dysfunction, shunt lesions, and pulmonary vein stenosis...

Neonates with a perinatal hypoxic insult and subsequent neonatal encephalopathy are at risk of acute pulmonary hypertension (aPH) in the transitional period. The phenotypic contributors to aPH following perinatal asphyxia include a combination of hypoxic vasoconstriction of the pulmonary vascular bed, right heart dysfunction, and left heart dysfunction. Therapeutic hypothermia is the standard of care for neonates with moderate-to-severe hypoxic ischemic encephalopathy. This review summarizes the underlying risk factors, causes of aPH in neonates with perinatal asphyxia, discusses the unique phenotypical contributors to disease, and explores the impact of the initial insult and subsequent therapeutic hypothermia on aPH...

INTRODUCTION: The mechanism of post-traumatic brain injury (TBI) hypoxemia involves ventilation/perfusion mismatch and loss of pulmonary hypoxic vasoconstriction. Inhaled nitric oxide (iNO) has been studied as an adjunct treatment to avoid the use of high positive end-expiratory pressure and inspired oxygen in treatment-refractory hypoxia. We hypothesized that iNO treatment following TBI would improve systemic and cerebral oxygenation via improved matching of pulmonary perfusion and ventilation...

Opioids are important tools for pain management, but abuse can result in serious health complications. Of these complications, respiratory depression that leads to brain hypoxia is the most dangerous, resulting in coma and death. Although all opioids at large doses induce brain hypoxia, danger is magnified with synthetic opioids such as fentanyl and structurally similar analogs. These drugs are highly potent, act rapidly, and are often not effectively treated by naloxone, the standard of care for opioid-induced respiratory depression...

RATIONALE: Obstructive sleep apnea (OSA) severity is typically assessed by the apnea-hypopnea index (AHI), a frequency-based metric that allocates equal weight to all respiratory events. However, more severe events may have a greater physiologic impact. OBJECTIVE: The purpose of this study was to determine whether the degree of event-related hypoxemia would be associated with the post-event physiologic response. METHODS: OSA patients (AHI>5/h) from the multi-center Canadian Sleep and Circadian Network cohort were studied...

Pentoxifylline is a non-selective phosphodiesterase inhibitor used for the treatment of peripheral artery disease. Pentoxifylline acts through cyclic adenosine monophosphate, thereby enhancing red blood cell deformability, causing vasodilation and decreasing inflammation, and potentially stimulating ventilation. We conducted a double-blind, placebo-controlled, <u>crossover, counterbalanced</u> study to test the hypothesis that pentoxifylline could lower blood viscosity, enhance cerebral blood flow and decrease pulmonary artery pressure in lowlanders following 11-14 days at 3800m...

BACKGROUND: An increasing number of hypertensive persons travel to high altitude while using antihypertensive medications such as betablockers. Nevertheless, while hypoxic exposure initiates an increase in pulmonary artery pressure (Ppa) and pulmonary vascular resistance (PVR), the contribution of the autonomic nervous system is unclear. In animals, β-adrenergic blockade has induced pulmonary vasoconstriction in normoxia and exaggerated hypoxic pulmonary vasoconstriction (HPV) and both effects were abolished by muscarinic blockade...