Visual Estimation of Blood Loss in Emergency Situations
Blood loss estimation is an important skill for emergency services personnel to have when treating victims of bleeding. It helps medical professionals assess the patient’s risk of hypovolemic shock and mortality, and decide whether to give a blood transfusion for optimal patient blood management.
While estimating blood loss as accurately as possible is important for medical professionals, the top priorities if you witness an accident or trauma are to call the emergency services and to act quickly to stop any further blood loss.
Techniques Used to Estimate Blood Loss
A systematic review of 140 different studies on blood loss estimation was conducted by Gerdessen et al. in 2020, in relation to obstetric blood loss. This study focused mostly on the immediate postpartum period and compared different blood loss estimation techniques.
In this study, it was noted that visual estimation of blood loss is one of the most widely used techniques, but that it has serious shortcomings—even in clinical settings. The study also noted that using pictograms and other visual measures didn't lead to notable improvements in the estimations made by trained physicians.
In addition to visual estimation of blood loss, there are several other methods that were mentioned in this study:
- Gravimetric: Blood loss is estimated by weighing surgical material saturated with blood and subtracting the dry weight of the material.
- Direct Measurement: Collection bags are placed under the patient (in this study, the patient who is giving birth) in order to collect all liquids lost during and after birth.
- Calculated Blood Loss: Various formulas are used to calculate the amount of blood lost compared to the patient’s total blood volume. These formulas typically take into account the patient's weight, height, and sex.
- Colorimetric Blood Loss Estimation: A smartphone app called Triton has shown promise in calculating blood loss. This app calculates the estimated blood loss by taking photos of used surgical gauze and canisters.
Estimating Blood Loss Using Gauze
Algadiem et al. (2016) proposed a visual blood loss estimation system to help estimate surgical blood loss using gauze. This method can be used both by laypeople and trained medical personnel.
Though it's challenging to determine actual blood loss with any certainty, this method can go some way to predicting blood loss in cases of traumatic injuries, in surgical settings (intraoperative blood loss), and during and after childbirth.
How to Predict Spilled Blood Volume Using Gauze
If you have a bleeding control kit, you’ll have at least a couple of wound dressings on hand, including gauze. As you apply direct pressure to a bleeding wound with gauze, you’ll notice the approximate saturation of the gauze and can use Algadiem et al.’s visual blood loss estimation guide (pictured below) to work out roughly how much blood has been lost.
For a more reliable blood loss estimation, this guide should be interpreted using the following guidelines:
- Estimate blood loss based on the size of the gauze and how much the blood has saturated the gauze.
- Change the gauze before it becomes supersaturated and drips with blood for a more accurate estimation.
- In surgical settings, keep in mind that saline-infused gauze is less absorbent than regular gauze.
Stemming Blood Loss Is Always the Priority
As noted by researchers, visual estimation of blood loss is a fairly unreliable method of estimating blood loss in cases of trauma and in surgical settings. While first responders might check your blood-soaked dressings to estimate how much blood a casualty has lost, your priority as a rescuer is to minimize how much blood is lost in a traumatic bleeding situation.
How to Reduce External Blood Loss Using a Bleeding Control Kit
Stopping severe blood loss requires swift and decisive action. The techniques you use to treat the injury will largely depend on the severity of the injury and where it is located on the body.
Using a Tourniquet to Stem Bleeding from an Arm or Leg
Tourniquets are the first line of defense for traumatic bleeding from limbs. Knowing how to apply a tourniquet can help to save a life in cases of extremity trauma.
Military-grade tourniquets such as the Combat Application Tourniquet® are ideal for controlling traumatic bleeding from an arm or a leg. In the worst-case scenario, you may need to make an improvised tourniquet. However, improvised tourniquets are often ineffective, which is why it’s far better to purchase a trauma kit before an accident occurs.
Using Hemostatic Gauze to Stem Bleeding
Hemostatic gauze is used to help blood clot more quickly and can be used to stop arterial bleeding if the wound is located on the trunk or if a tourniquet hasn’t been sufficient to stem bleeding from an extremity. To use hemostatic gauze:
- Push the hemostatic gauze into the wound and apply direct pressure for at least three minutes.
- Elevate the bleeding limb.
- If bleeding continues, additional gauze can be added to the wound. Never remove the initial gauze, as that can reverse some of the clotting benefits achieved.
Using a Chest Seal for Penetrating Chest Trauma
A chest seal should be used in the case of a gunshot wound that penetrates the chest. Chest seals stop air from entering the chest, making breathing much easier. To apply a chest seal:
- Uncover the chest and locate the wound.
- Place the seal over the wound, following the instructions on the packet.
- Look for an exit wound on the other side of the body; if there is one, place a seal over it too.
When It Comes to Blood Loss, Prevention Is Better than Cure
Although estimating blood loss is an important factor in successful emergency medicine, stopping blood loss should be the absolute priority in any case of traumatic bleeding. Workplaces, households, and even vehicles should be equipped with trauma kits so that you can treat severe blood loss immediately and reduce a patient’s chances of bleeding out.
Once medical professionals arrive on the scene and stabilize the patient, they may assess any blood-soaked dressings or clothing that traveled with the patient to estimate how much blood the patient has lost. They can then decide on the most appropriate course of treatment to help the patient recover.
