Medically the evaluation by Debra Sullivan, Ph.D., MSN, R.N., CNE, COI — created by Rachel Nall, MSN, CRNA — to update on July 18, 2017

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The lot of blood in the person body is usually equivalent to 7 percent of human body weight. The mean amount that blood in her body is one estimate since it have the right to depend on how much you weigh, your sex, and also even whereby you live.

Babies: Babies born full-term have about 75 milliliters (mL) of blood every kilogram of their body weight. If a infant weighs around 8 pounds, they’ll have about 270 mL that blood in their body, or 0.07 gallons. Children: The mean 80-pound kid will have around 2,650 mL of blood in your body, or 0.7 gallons. Adults: The mean adult weighing 150 come 180 pounds have to have around 1.2 to 1.5 gallons that blood in your body. This is about 4,500 come 5,700 mL. Pregnant women: To assistance their farming babies, pregnant women generally have all over from 30 come 50 percent more blood volume than women who are not pregnant. This is around 0.3 come 0.4 extr gallons the blood.

Sometimes the quantity of blood in the person body can differ based on where friend live. Because that example, people who live in ~ high altitudes have much more blood because there isn’t as much oxygen at higher altitudes.

If you lose too much blood, your mind doesn’t get sufficient oxygen to support life. Civilization who experience significant injury and also trauma, such together a vehicle accident, may shed blood really quickly. Shedding an too much amount the blood is well-known as hemorrhagic shock. Physicians categorize hemorrhagic shock into four classes based on how much blood is lost. In course IV, the lot of blood loss deserve to be fatal.

Here are the great of hemorrhagic shock:

class Iclass IIclass IIIclass IV
blood ns (mL)up to 750750 to 1,0001,500 to 2,000greater 보다 2,000
blood lose (% that blood volume)up to 1515 come 3030 come 40greater than 40
pulse price (per minute)less than 100100 come 120120 to 140greater than 140
blood pressurenormal or increaseddecreaseddecreaseddecreased
respiratory rate (per minute)14 come 2020 to 3030 come 40greater 보다 35
urine calculation (mL every hour)greater 보다 3020 to 305 to 15negligible
mental statusslightly anxiousmildly anxiousanxious, confusedconfused, lethargic

Your blood pressure and heart price will remain close to regular as you lose up to 30 percent of your blood, or as much as 1,500 mL that blood (0.4 gallons). After losing this amount of blood, friend will experience the following:

You’ll begin to have a rapid heart rate greater than 120 beats per minute.Your blood pressure will drop.Your breathing price will walk up.

If you lose an ext than 40 percent of her blood, you will certainly die. This is about 2,000 mL, or 0.53 gallons the blood in the typical adult.

It’s crucial to obtain to a hospital to start receiving blood transfusions to prevent this.

Learn more: just how long go a blood transfusion last? »

Your physician won’t usually directly measure the amount of blood that you have due to the fact that they deserve to estimate it based upon other factors and tests. For example, a blood test well-known as a hemoglobin and hematocrit test can estimate exactly how much blood is in your body compared with the amount of fluid in your body. Then, your physician can consider your weight and also how hydrated you most likely are. Every one of these factors can indirect measure how much blood volume you have.

If you suffer a significant trauma that reasons blood loss, physicians will commonly use your weight as the starting point come guess exactly how much blood friend have. They will certainly then use factors like her heart rate, blood pressure, and also breathing price to estimate just how much blood may have been lost. They’ll also shot to store track that any additional blood loss therefore they can quickly replace it through a blood transfusion.

Read more: how to lower your heart rate »


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Medically reviewed by Debra Sullivan, Ph.D., MSN, R.N., CNE, COI — created by Rachel Nall, MSN, CRNA — update on July 18, 2017