Effects of high altitude exposure on cerebral hemodynamics in normal subjects
Abstract
BACKGROUND AND PURPOSE: Acute mountain sickness (AMS) may be an early stage of high altitude cerebral edema. If so, AMS could result from an alteration of dynamic autoregulation of cerebral blood flow resulting in overperfusion of capillaries and vasogenic cerebral edema.
METHODS: We measured middle cerebral artery blood flow velocity (Vmca) by transcranial Doppler and arterial blood pressure by finger plethysmography at 490 m and 20 hours after arrival at 4559 m in 35 volunteers who had been randomized to tadalafil, dexamethasone, or placebo in a study on the pharmacological prevention of high altitude pulmonary edema. A dynamic cerebral autoregulation index (ARI) was calculated from continuous recordings of Vmca and blood pressure during transiently induced hypotension.
RESULTS: Altitude was associated with an increase in a cerebral-sensible AMS (AMS-C) score (P<0.001) and with a decrease in arterial oxygen saturation (Sao2), whereas average Vmca or ARI did not change. However, at altitude, the subjects with the lowest ARI combined with the lowest Sao2 presented with the highest AMS-C score (P<0.03). In addition, a stepwise multiple linear regression analysis on arterial Pco2, Sao2, and baseline or altitude ARI identified altitude ARI as the only significant predictor of the AMS-C score (P=0.01). The AMS-C score was lower in dexamethasone-treated subjects compared with high altitude pulmonary edema-susceptible untreated subjects. Neither tadalafil nor dexamethasone had any…
How strong is the evidence?
Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design. Reported size: 35 participants or records.
Read the paper
Related studies
- Protective effects of tadalafil and N-acetyl cysteine therapy on cisplatin-induced testicular toxicity
- The Use of Generative AI for Scientific Literature Searches for Systematic Reviews: ChatGPT and Microsoft Bing AI Performance Evaluation
- Sildenafil as a Candidate Drug for Alzheimer’s Disease: Real-World Patient Data Observation and Mechanistic Observations from Patient-Induced Pluripotent Stem Cell-Derived Neurons
- Ozone-modified properties of pumpkin seed oil as anti-H. pylori, anticancer, anti-diabetic and anti-obesity agent
- Effectiveness of Low-Intensity Extracorporeal Shock Wave Therapy in Erectile Dysfunction: An Analysis of Sexual Function and Penile Hardness at Erection: An Umbrella Review
- Molecular Docking of Silymarin as a Ligand for Aromatase Enzyme and HIV-1 Reverse Transcriptase Using Molegro Virtual Docker
Go deeper in Evidence Hub
Evidence Hub adds a study data sheet (design, sample size, evidence level, key numbers), an AI summary and a chat grounded in the paper's text.