Lost in Space Is It Safe to Lose Consciousness Again and Again

(CNN)The lack of gravity astronauts encounter during spaceflight makes returning to the force of World'south gravity a trivial disorienting. And when they render to World, they faint.

A new study published Friday in Circulation, the American Heart Clan'due south journal, has identified a manner to avert that.

Surgeons assigned to some of the first astronauts to get into space during NASA's Mercury program noticed very few changes when they monitored heart rate, blood pressure and body temperature.

"But what changed was when they returned to Earth," said Nib Carpentier, Apollo 11 flight surgeon. "The middle charge per unit was increased post-flight and claret force per unit area was seen to be lower. And on the concluding Mercury flight, which was 34 hours, when Gordon Cooper got out of the spacecraft and stood up, his heart rate went really high, 170, 180. And his claret pressure dropped, he felt like he was going to faint. But once he started moving, things got better and he was able to walk across the deck."

In that location was business that this could become progressive with longer missions in the Apollo program that could last up to 14 days.

Orthostatic hypotension occurs when the blood rushes to the feet and abroad from the encephalon as someone stands up after sitting or lying down. This causes a temporary drop in blood pressure, which tin atomic number 82 to dizziness or fainting.

"One of the biggest bug since the inception of the manned space program has been that astronauts have fainted when they came downwards to Globe. The longer the fourth dimension in a gravity-gratuitous surround space, the greater the hazard appeared," said Dr. Benjamin Levine, senior study author and a professor of Internal Medicine at UT Southwestern Medical Centre and Managing director of the Found for Exercise and Environmental Medicine, a collaboration between UT Southwestern and Texas Health Presbyterian Hospital Dallas. "This trouble has bedeviled the space programme for a long time, but this condition is something ordinary people frequently experience besides."

People with sure health conditions or using bed rest to recover from an injury tin can also experience this sensation.

The study involved 12 astronauts, eight men and four women betwixt the ages of 43 and 56. They spent 6 months in space aboard the International Space Station between 2009 and 2013.

As is standard exercise for space station astronauts, they exercised for 2 hours each twenty-four hour period of their mission. This included endurance and resistance training. Astronauts on the station regularly exercise to prevent the loss of os mass and muscle, including cardiovascular musculus loss.

This exercise countermeasure evolved over time based on studies, Levine said.

And upon returning to Earth, the astronauts received saline 4 fluids.

"Space causes a loss of plasma volume that is accentuated by the re-entry process," Levine said. "Practice keeps the centre size and function intact and fluid fills it in preparation for Earth'south gravity."

Earlier, during and after their missions, the astronauts heart rate and claret pressure was recorded over a 24-60 minutes catamenia.

Their blood pressure just shifted minimally and none of them fainted or experienced dizziness after landing and performing activities over a 24-hour flow.

Levine said this is the first study to show that astronauts aren't experiencing these symptoms after landing every bit long as they do in flight and receive a saline infusion when they return.

"What surprised me the well-nigh was how well the astronauts did after spending half-dozen months in space," Levine said. "I thought there would exist frequent episodes of fainting when they returned to Globe, but they didn't have any. Information technology'southward compelling evidence of the effectiveness of the countermeasures--the do regimen and fluid replenishment."

There are a few considerations for the written report, including its small samples size and the fact that the researchers don't know if the claret pressure readings happened when the astronauts were awake or asleep. They also don't know what would have happened if the astronauts didn't exercise or receive IVs upon render because all of them did.

But the findings could help people on World also.

"Understanding the physiology of infinite flight tin can be helpful for understanding many weather experienced past not-astronauts. For instance, the exercise program our lab adult for the space program is already helping people with a fainting condition known every bit postural orthostatic tachycardia syndrome (POTS)," Levine said. "Equally we gear up to celebrate the 50th anniversary of the Apollo eleven moon landing, it'southward exciting to think of how our exploration in and of space can lead to of import medical advances here on Earth."

Adjacent, the researchers are studying ways to mitigate other furnishings of spaceflight on the human body.

"We are currently testing strategies to unload the heart and brain at night using a sleeping sac hooked upward to a vacuum pump," Levine said. "We hope that this volition prevent the remodeling behind the heart that is causing some astronauts to take diminished vision. Nosotros just submitted 2 grants to NASA to examine longer durations stays on the ISS, through i year. Nosotros are specially interested in the atria (and risk of atrial fibrillation) and the possibility that spaceflight in general, and infinite radiations in particular could advance atherosclerosis."

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Source: https://www.cnn.com/2019/07/19/health/astronaut-exercise-iv-faint-scn/index.html