Excessive Oxygen Increases Mortality in Severely Ill Patients

A new review suggests that supplemental oxygen, when given too liberally to acutely ill adult patients, increases the risk of death without providing added benefit.

Researchers at McMaster University (Hamilton, ON, Canada) and St. Joseph's Healthcare (St. Joe’s; Hamilton, Canada) searched electronic academic databases from inception through October 2017 for randomized controlled trials that compared liberal and conservative oxygen therapy protocols and death rates, as well as their impact on disability, infection, and hospital length of stay. A total of 25 studies encompassing 16,037 adult patients with sepsis, stoke, trauma, emergency surgery, heart attack, or cardiac arrest were identified.

The results revealed that compared to a conservative oxygen strategy, a liberal oxygen strategy--defined as a median baseline peripheral oxygen saturation (SpO2) of 96%--increased mortality by an average of 21%, signifying an additional death for every 71 patients treated with a liberal oxygen strategy. Further analyses suggested that the more supplemental oxygen patients were given, the higher their risk was for death, but the incidence of other conditions, such as infections or length of hospital stay, were similar between the two groups. The study was published on April 28, 2018, in The Lancet.

“Patients are frequently given supplemental oxygen and at excessive levels. Our results provide much-needed clarification by showing, with high-quality evidence, that administering too much supplemental oxygen increases mortality among a broad range of acute illnesses,” said lead author Derek Chu, MD, of McMaster University. “A simple change to current practice, being more moderate and cautious with how much oxygen is administered to acutely unwell patients, could save lives.”

The use of oxygen in medicine became common around 1917, and is believed to be the most common treatment given in hospitals in the developed world. It can be delivered by a nasal cannula, facemask, or inside a hyperbaric chamber. In most conditions a SpO2 saturation of 94–98% is recommended, while those at risk of carbon dioxide (Co2) retention saturations of 88–92% are preferred, and in those with carbon monoxide (CO) toxicity or cardiac arrest they should be as high as possible. Air is typically 21% oxygen by volume, while oxygen therapy increases this by some amount up to 100%.

Related Links:
McMaster University
St. Joseph's Healthcare