Breathing in extra oxygen enhances blood vessel function in the brains of people with chronic obstructive pulmonary disease (COPD), according to a new study published in the journal Experimental Physiology.
The findings show why oxygen therapy may help reduce incidence of dementia among patients with lung disease.
COPD is a collective term for a group of lung conditions that cause long term breathing problems. Patients with this condition are at greater risk of memory loss and dementia, commonly believed to be the result of reduced brain oxygen levels due to poor lung function.
Some studies have shown that giving COPD patients additional oxygen can lower their risk of developing dementia, but, until now, the mechanisms underlying this positive effect have not been fully investigated.
In a new study, researchers used ultrasound to view and measure blood flow in the brain in COPD patients at rest, before and during delivery of additional oxygen. The oxygen was delivered through the nasal passage for 20-30 minutes.
In addition to measuring blood flow in the brain, the research team also analyzed the connection between brain activity and blood flow in the brain. To do this, patients began with their eyes shut, then had to open them and read standardized text. This experiment was designed to boost activity in the brain, and in turn, increase blood flow in the brain to provide adequate oxygen supply.
The researchers compared the ultrasound results with a measurement of blood oxygen levels which allowed them to estimate how much oxygen delivery to the brain increased during the open-eyes reading test.
They found that blood flow and oxygen delivery to the brain was significantly increased during reading. This was due to blood vessels in the brain becoming dilated in response to the greater oxygen demand when the brain was active. Researchers concluded that when COPD patients receive additional oxygen it improves the function of blood vessels in the brain.
However, COPD patients typically use this extra oxygen therapy throughout the day and for long periods of time, potentially years. This experiment was not able to determine the impact of long term oxygen therapy on the function of blood vessels in the brain.
But despite these potential limitations, this work has set the foundation for the researchers to study the biological systems that control oxygen delivery to the brain.
COPD affects primarily middle-aged or older adults who smoke. Symptoms often include breathlessness and a chesty “smokers cough.”
Source: The Physiological Society