A new study has found that placing older, sedentary adults in a simulated high-altitude environment with reduced oxygen for a week before major surgery greatly improved their hemoglobin levels, addressing a common preoperative problem, anemia, that can lead to surgical complications.
Some factors related to higher rates of surgical complications and postoperative mortality include a patient’s low fitness levels, high BMI, sedentary lifestyle, and anemia, which is where the blood has lower-than-normal levels of oxygen-carrying hemoglobin. Multiple review studies have found that pre-operative anemia is a particular problem, seen in between 30% and 40% of patients about to undergo major surgery, and is a poor prognostic indicator. Often, anemia is treated with blood transfusions during surgery, which has been found to result in worse outcomes.
Aware that athletes using altitude or hypoxic training – exercising in, living in, or otherwise breathing oxygen-reduced air – have improved hemoglobin levels and physical wellness, a study led by researchers from King’s College London investigated whether exposing older, sedentary adults to a simulated high altitude environment pre-operatively would provide any health benefits.
“We know that athletes can use hypoxic canopies over their bed to simulate altitude exposure and that altitude can induce performance benefits after two to three weeks, even in people who are extremely fit,” said Thomas Smith, the study’s corresponding author. “We were interested in whether this approach could also benefit older patients ahead of major surgery, who, due to sedentary lifestyles and low levels of fitness, are more at risk of negative postoperative outcomes.”
The study recruited eight unfit volunteers with an average age of 64 to spend two weeks undergoing ‘altitude prehabilitation,’ living at the National Altitude Training Center in Ireland, a ‘hypoxic house’ in which the oxygen levels in the air are tightly controlled. For one week, the house contained normal air (21% oxygen); during the second week, the oxygen levels were mildly reduced to 15%, the equivalent of flying in an aircraft at around 8,000 ft (2,438 m). Participants underwent repeated cardiopulmonary exercise tests during their two-week stay.
The researchers found that simulated high altitude produced a substantial (13%) increase in hemoglobin but had no overall effect on aerobic fitness. While there was an indication that participants could exercise longer and harder following a week of reduced oxygen, these changes were not statistically significant overall when compared with the control week. The period of hypoxia was well-tolerated by participants.
The researchers say that if the increase in hemoglobin induced by simulated altitude were translated to the clinical setting, it would be considered highly likely to improve patient outcomes as it may remove the need for pre- or intraoperative blood transfusion to treat anemia. The benefits may even extend to non-anemic patients.
In practice, the researchers say that small-scale hypoxic canopies could be provided to patients to use in the weeks before surgery, noting that some gyms already have hypoxic chambers and training rooms.
The study’s findings suggest this novel concept should be researched further.
“While this study suggests that simulated altitude exposure may have potential advantages for older and sedentary patients, further studies are needed to explore this for home-based altitude prehabilitation,” Smith said.
The study was published in the journal Anaesthesia.
Source: King’s College London