• Question: How does putting pressure on an open wound stop the bleeding? Wouldn’t it make us bleed more?

    Asked by peter296 on 28 Apr 2020.
    • Photo: Louise Mc Grath

      Louise Mc Grath answered on 28 Apr 2020:

      Hi peter296,

      Great question! By applying pressure to an open wound, essentially you are slowing the blood flow, which gives the blood time to clot. When the blood clots it prevents the blood from escaping through the open wound. The blood can be clotted in various other ways, such as elevating the leg, as the blood will slow down if it has to go against gravity and therefore will clot, or by using gauze, and wrapping it tightly around the wound.

      Think of it like a river, the water will continue to flow unless you block it. If you build a dam, then you are stopping the flow of water.

    • Photo: James Collins

      James Collins answered on 28 Apr 2020:

      Hi peter296, great question! The idea of putting pressure on an open wound is to slow down the blood flow enough so that different things in the blood can cause the blood to clot, a bit like a scab when you scrape your knee! Hope this helps!

    • Photo: Sonia Lenehan

      Sonia Lenehan answered on 28 Apr 2020:

      Hi peter296,

      Louise gave a very clear answer below! The only thing I would add is that putting pressure on the wound slows the blood flow down enough for the plasma and the fibrin in your blood to grab hold of the wound and to form a blood clot in the wound to stop it bleeding and allow it to heal!

    • Photo: Simon Spichak

      Simon Spichak answered on 28 Apr 2020:

      Great question! To find out why, let’s take a look at how open wounds hel! When we start to bleed, our body prepares its response! It has stop the bleeding in order to repair the damage – this involves sending along some special chemicals from the body to relax the muscles around our blood vessels. This will quickly increase their diameter, and allow more blood to flow to the site of the damage! Now in this blood, we’ve got sticky cells called platelets that rush to this site to prevent more blood from exiting. So once we add pressure into the equation, we can stop blood from flowing it and since blood contains platelets – they will clot even faster and stop the blood! In addition, you slow down the blood at the site of the wound increasing the chance that all those platelets will stick together to clot!

    • Photo: Jean O'Dwyer

      Jean O'Dwyer answered on 28 Apr 2020: last edited 28 Apr 2020 8:48 am

      Great question!

      Imagine a garden hose with a puncture in it- water will escape out of the puncture because it is under high pressure. If you cover the hole, no water will come out as you have stabilized the pressure within the hose.

      Same approach for blood, except it’s a bit more complicated. In order to stop bleeding, our blood needs to clot- to do this, it must first form what’s called a platelet plug. These plugs start as a very thin layer of platelets (cells), which are easily broken- if you think of the hose again, all the escaping water/blood will break this layer. BUT, if we apply pressure and stop the blood escaping through the wound, the platelet plug will form in full (takes around one minute) and the proper clotting process will start- once it has clotted, we no longer need to apply pressure, as the ‘hole’ has been filled.

    • Photo: Fiona Malone

      Fiona Malone answered on 28 Apr 2020:

      By applying pressure you are slowing down and hopefully slowing the flow of blood to the site of injury. Elevating helps too! This way you are creating a good environment for clotting and repair to begin in the wound

    • Photo: Min Yap

      Min Yap answered on 28 Apr 2020:

      Applying pressure on an open wound actually slows down the blood flow and helps the blood clot to stop the bleeding.

    • Photo: Aisling Ryan

      Aisling Ryan answered on 28 Apr 2020:

      Great question! When our bodies are functioning on a normal day our blood is running around our body delivering oxygen. When there is a wound some blood begins to escape from the body. Think of a pipe with water running through. If there was a random hole in the pipe water would start to escape from this hole, right? If you put your finger on the hole and press down you would be covering the hole and allowing the water to flow through the pipe as normal. This is the same concept as putting pressure on a wound. By applying pressure you are stopping the blood from flowing out of the wound, or slowing it down depending on how bad the wound is. If you didn’t apply pressure it would flow out as quickly as it can. By applying pressure you make it harder for the blood to flow out. Hope this makes sense!

    • Photo: Florence McCarthy

      Florence McCarthy answered on 30 Apr 2020:

      It restricts the blood flow to allow time for a clot to form

    • Photo: Lucy Blennerhassett

      Lucy Blennerhassett answered on 6 May 2020:

      It helps your blood to clot I believe! And thats about as in depth as I’ll go (I am a geoscientist after all) 🙂