What Is a Distal Pulse & Why Does It Matter in Bleeding Emergencies?
When talking about tourniquet application, rescuers are instructed to feel for a "distal pulse"— or, more specifically, to confirm the absence of a distal pulse and thus ensure that the tourniquet has stopped the blood flow. But what exactly is a distal pulse and how do you feel for it?Â
Having an awareness of the distal or peripheral pulses, where they are located, and how to check them can help you ensure that you've applied a tourniquet correctly in an emergency. For the untrained lay responder, this knowledge can be instrumental in saving the life of a bleeding victim.
What Is a Distal Pulse?
In medical jargon, "distal" or "peripheral" refers to pulse points that are the furthest from the trunk whereas "proximal" or "central" refers to the pulse points that are closest to the trunk.Â
The distal pulses include the:
- Radial artery (on the inner thumb side of the wrist)
- Ulnar artery (in the inner middle of the wrist)
- Dorsalis pedis (on the top of the foot)
- Posterior tibial artery (behind the outer ankle)
The medial pulses include the:
- Brachial artery (inside the elbow)
- Popliteal artery (under the knee)
Central or proximal pulses include the:
- Carotid arteries (in the neck)
- Axillary artery (in the underarm)
- Femoral artery (in the groin)
When we talk about pulse, we're talking about the rate of blood flowing through the arteries rather than the veins. The arteries are the blood vessels that carry oxygen-rich blood away from the heart whereas veins are the blood vessels that carry carbon dioxide-rich blood back to the heart.
In clinical medicine, medical professionals use distal pulse palpation to detect abnormalities like:
- Deep venous thrombosis
- Arterial insufficiency
- An irregular pulse, which could be evidence of atrial fibrillation
Where Is the Distal Pulse?
There are four main distal pulse points: two on the wrist and two on or around the feet. Injuries higher than the elbow or knee may warrant checking the brachial or popliteal pulses, respectively. There’s no reason to check the axillary pulse or femoral pulse as tourniquets can’t be used on the trunk.
Using these descriptions, practice finding these pulse points on your body and a family member or friend so that you'll have an easier time finding them on a bleeding victim in an emergency situation.
Location of the Radial Pulse
The radial pulse is located on the flexor aspect of the wrist. You can find it by extending and flexing your wrist and looking for the tendon. The radial artery is just next to the tendon on the outside.
Location of the Medial Pulse
The medial pulse is in the middle of the inside of the wrist, just next to the medial tendon on the inside. When you extend and flex your wrist, you should be able to see both of the tendons and locate their respective arteries.
Location of the Brachial Pulse
The brachial pulse is located medial to the biceps tendon in the antecubital fossa, or in simple terms, slightly to the inside of the middle of your inner elbows.
Location of the Dorsalis Pedis Pulse
The dorsalis pedis artery is located on the dorsum (top) of the foot, just inside the extensor tendon that connects to the big toe.Â
Location of the Posterior Tibial Pulse
The posterior tibial artery is located just behind the "medial malleolus," or the outer ankle.
Location of the Popliteal Pulse
The popliteal artery is located in the middle underside of the knee (the popliteal space). It's easier to find if the knee is flexed. You might need to press quite hard to find it.
How to Check the Distal Pulse
To check the distal pulse, compress each artery near the surface of the body with the pads of your index, middle, and ring fingers:
- The pad of the index finger occludes the pulse pressure.
- The pad of the middle finger gives you an approximate sense of the blood pressure.
- The pad of the ring finger helps to cancel out the effect of the ulnar pulse in your own hand.
While performing distal pulse palpation on someone else, it can help to place three fingers on your neck to make sure you're feeling their pulse rate and not your own. It's also recommended to start with the more distal (distant) pulses and work your way toward the heart. For an injury above the elbow or knee, you might not feel a pulse on the foot or wrist but could still feel a pulse in the elbow or knee.
Why Is the Distal Pulse Important in Cases of Traumatic Bleeding?
Distal pulse palpation is important in the context of traumatic bleeding because rescuers need to make sure a tourniquet is tight enough to stop arterial blood flow from a wound on an upper or lower limb. When palpating for a distal pulse in the case of life-threatening bleeding, the point is to ensure that there is no pulse, proving that you've effectively stopped the blood flow below the point of tourniquet application.
Tourniquets can be found in bleeding control kits and are used to stop blood flow temporarily when a wound to the upper or lower extremities is causing severe bleeding. If the tourniquet is not tight enough, blood can continue to flow past the tourniquet and exit through the wound.Â
What Happens If a Tourniquet Isn’t Tight Enough to Stop the Distal Pulse?
Remember, the goal when using a tourniquet is to stop the distal pulse completely. A tourniquet that isn't quite tight enough could obstruct only venous blood flow—blood flowing back to the heart through the veins. This increases the likelihood of compartment syndrome and muscle and nerve damage without decreasing the victim's risk of bleeding out.Â
Insufficient pressure is one reason why rescuers should always use a commercial tourniquet if available rather than improvising with a bandana or scarf. Improvised tourniquets are often 60-90% ineffective. Please refer to our guide on how to apply a tourniquet correctly when using a commercial or improvised tourniquet.
How Reliable Is Distal Pulse Palpation?
Studies have shown that distal pulse palpation isn't 100% reliable. In fact, research shows that medical professionals can assess distal pulse incorrectly up to 30-60% of the time, especially in busy outpatient clinics.Â
When feeling for a distal pulse in a victim with severe bleeding or a crushed limb, remain calm, take your time and compare the pulse with the same pulse point on the other side. If in doubt, check whether blood is still flowing from the wound and tighten the tourniquet (or apply a second tourniquet underneath the first one) until the blood flow stops or is reduced to a slow dark-red ooze.
Cutting off blood flow through an artery is necessary to prevent a patient with severe bleeding from bleeding out (which can be fatal). However, if a tourniquet is left on for too long, the tissues can experience severe ischemia (lack of blood flow and hence oxygen) and become damaged or die. Based on studies, tourniquet use is now limited to two hours after application, after which any damage to the muscles, tissues, and nerves will usually resolve in a few weeks.Â
Please note: A tourniquet should only be removed by a medical professional once the victim reaches a hospital. A lay rescuer should never remove or loosen a tourniquet.
Knowing How to Check a Distal Pulse Could Save Somebody's Life
Even if you're not a medical professional, it’s valuable to know where to find the distal arteries and how to ensure the absence of a distal pulse upon tourniquet application. In doing so, you can better ensure that the tourniquet has been applied tightly enough to stop blood flow to a wound on an upper or lower extremity. This, in turn, will prevent the patient from losing too much blood and will reduce the likelihood of compartment syndrome.
Before an emergency occurs, practice feeling for the distal pulse on yourself and any willing volunteers. When you're in the heat of an emergency, you'll have a much easier time remembering where to find the distal pulse so that you can check that the tourniquet is tight enough to stop blood flow to the wound.
