Adding ice to medics’ kits could help patients survive blood loss | Science News for Students

Adding ice to medics’ kits could help patients survive blood loss

Cooling the face may save lives by keeping blood pressure up
Jun 2, 2017 — 7:10 am EST
ice cubes

Medics may have a new tool to help severely injured patients: ice. A bag of it on the face could help to keep blood pressure up in those suffering severe blood loss.

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Keeping a cool attitude helps when handling an accident victim who has lost a large amount of blood. But keeping patients cool might also help, a new study finds. It might save their lives.

Here’s why: Losing a lot of blood can lead to a dangerous loss of blood pressure. That can limit how much blood, and therefore oxygen, reaches the brain and other vital organs. If deprived of enough oxygen, those tissues — and the patient — could die.

The body doesn’t have to spill most of its blood for this to happen. Losing about 2 liters (a half gallon) out of the 5 liters (1.3 gallons) or so in the body could be fatal. In fact, most deaths among army troops are due to excess blood loss — even if the inflicted wounds do not directly affect a vital organ, says Victor Convertino. A physiologist, he studies body functions at a research institute of the U.S. Army in Houston, Texas. He was not involved in this study.

Convertino thinks medics and others can save some lives if they can maintain adequate blood pressure — and thereby blood flow — to vital tissues until the victim reaches the hospital. (Vital tissues include the heart and brain.) Once there, blood transfusions can take over.

Blair Johnson may have found a way to achieve this. He is a physiologist at the University of Buffalo in New York. There, he focuses on developing effective ways to maintain blood pressure in the body after potentially catastrophic blood loss. He described a potential new first-aid approach to cope with such situations, April 26, at the Experimental Biology meeting in Chicago, Ill. His idea is simple: Just cool the victim’s face.

The concept

Johnson drew inspiration from the body's natural response to a drop in the supply of oxygen to its tissues. Consider when you dive into a swimming pool. The body abides by a simple rule: When in crisis, save the vital organs. So, while underwater, the body turns on a so-called “diving reflex.” It directs to the brain and heart what limited oxygen is available. "Your blood pressure goes up, and your heart rate falls down, especially if the water is cold," Johnson explains.

Think of blood vessels as a system of fluid-filled tubes. When the body is exposed to cold water, these tubes narrow. If the fluid volume stays the same, the overall pressure in the system increases.

Cooling the entire body of an accident victim is impractical. But cooling just the face should be possible, says Convertino — even when dealing with injuries on the battlefield.

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A volunteer lies with his lower body inside a test chamber. A pump sucks the air out of the chamber, tricking the body into believing it has suffered blood loss.
Blair Johnson/University of Buffalo

To test the idea, Johnson's group recruited 10 people to take part in an experiment. None had to actually lose blood. Instead, the scientists tricked their bodies into believing that they had. To do this, they sealed each person’s body from the waist down in a chamber. Then a vacuum sucked air out of the chamber. This dropped the pressure inside. Blood rushed to the lower body of the volunteers because of the pressure difference between the chamber and rest of the room. This mimics how the body reacts to losing about 1 liter (0.3 gallon) of blood.

While the machine simulated blood loss, the researchers treated the recruits’ faces. They placed a bag containing a mix of either ice and water or just water onto the forehead and over the eyes. Placing the cold ice-water bag on the face of volunteers for 15 minutes increased blood pressure, the scientists found. In fact, it pushed blood pressure close to normal. This treatment also decreased the volunteers’ heart rate. Placing a bag of only water on the face of volunteers, though, did not affect their blood pressure and heart rate.

This face-cooling treatment is not a long-term fix, Convertino cautions. It is likely to help most when a hospital can be reached within 15 minutes. "If it gets past 30 to 60 minutes, it may not be so practical," he says. After that time, the tissues may begin experiencing too much oxygen loss and die.

Power Words

(for more about Power Words, click here)

biology     The study of living things. The scientists who study them are known as biologists.

blood pressure     The force exerted against vessel walls by blood moving through the body. Usually this pressure refers to blood moving specifically through the body’s arteries. That pressure allows blood to circulate to our heads and keeps the fluid moving so that it can deliver oxygen to all tissues. Blood pressure can vary based on physical activity and the body’s position. High blood pressure can put someone at risk for heart attacks or stroke. Low blood pressure may leave people dizzy, or faint, as the pressure becomes too low to supply enough blood to the brain.

blood vessel     A tubular structure that carries blood through the tissues and organs.

chemical     A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

diving reflex     A reflex in mammals that can allow them to survive low levels of oxygen when they are in cold water. As soon as mammals plunge their faces into ice water, their veins constrict and their heart rate slows.

heart rate     Heart beat; the number of times per minute that the heart — a pump — contracts, moving blood throughout the body.

organ     (in biology) Various parts of an organism that perform one or more particular functions. For instance, an ovary is an organ that makes eggs, the brain is an organ that makes sense of nerve signals and a plant’s roots are organs that take in nutrients and moisture.

oxygen     A gas that makes up about 21 percent of Earth's atmosphere. All animals and many microorganisms need oxygen to fuel their growth (and metabolism).

physiology     The branch of biology that deals with the everyday functions of living organisms and how their parts function. Scientists who work in this field are known as physiologists.

pressure     Force applied uniformly over a surface, measured as force per unit of area.

tissue     Made of cells, any of the distinct types of materials that make up animals, plants or fungi. Cells within a tissue work as a unit to perform a particular function in living organisms. Different organs of the human body, for instance, often are made from many different types of tissues.

transfusion     The transfer of donated blood or blood products into the circulatory system of a person or animal.

vacuum     Space with little or no matter in it. Laboratories or manufacturing plants may use vacuum equipment to pump out air, creating an area known as a vacuum chamber.

NGSS: 

  • MS-PS1-4

Citation

Meeting:​​ ​B. Johnson et al. Face cooling increases blood pressure during simulated blood loss. Experimental Biology 2017. April 26, 2017. Chicago, Ill. Poster W311, 1087.5.