Estimated Blood Loss (EBL) is a measurement made during surgery to approximate the amount of blood a patient has lost. This calculation is closely monitored by the surgeon and anesthesiologist. The EBL is not a passive observation; it actively guides the medical team’s actions and decisions throughout the procedure.
The Importance of Monitoring Blood Loss
Tracking blood loss is an important part of patient safety in the operating room. The primary reason for this monitoring is to determine if a blood transfusion is necessary. Decisions about transfusion are guided by the EBL, along with the patient’s hemoglobin levels and overall condition, as a significant drop in blood volume can lead to serious complications.
Excessive blood loss can lead to hypovolemic shock, a condition where the heart cannot pump enough blood to the body. Continuous EBL monitoring acts as an early warning system, allowing the team to intervene before a patient’s condition becomes unstable. The information also influences post-operative care, especially in managing anemia resulting from the surgery.
The EBL provides a shared point of reference for the surgical team, facilitating clear communication between the surgeon and the anesthesiologist. This shared number ensures everyone is aligned on the patient’s status and the potential need for intervention. This collaborative tracking helps prevent both under- and over-resuscitation.
How Blood Loss is Estimated
One common technique involves measuring the contents of suction canisters that collect blood and irrigation fluids from the surgical site. To determine the blood volume, the team subtracts the amount of saline irrigation fluid used from the total volume collected. This method can be prone to overestimation because it is difficult to measure how much irrigation fluid is mixed with the blood.
Another technique is the gravimetric method, which involves weighing surgical sponges and laparotomy pads. Before the procedure, the dry weight of all sponges is known, and as they become saturated with blood, they are collected and weighed. The original dry weight is subtracted from the saturated weight to calculate the volume of blood absorbed, assuming one gram of weight equals one milliliter of blood.
Surgical teams also rely on visual estimation, though it is considered the most inaccurate method. The surgeon and anesthesiologist look at the surgical field, sponges, and suction canister to make an educated guess about the volume of blood lost. Despite its imprecision, it is often used with other methods to form a consensus. To improve accuracy, some hospitals use advanced technologies like colorimetric analysis, which measures the hemoglobin concentration in collected fluids.
Factors Influencing Blood Loss During Surgery
The amount of blood lost during an operation is influenced by the type of procedure. Major surgeries involving highly vascular organs, like liver resections or certain cardiac procedures, have a higher potential for bleeding. Extensive spinal surgeries are also known for substantial blood loss, while less invasive procedures involve minimal EBL.
Patient-specific characteristics also determine surgical blood loss. Individuals with pre-existing bleeding disorders may have difficulty forming clots, leading to increased bleeding. The use of anticoagulant medications (blood thinners) must be managed before surgery to reduce this risk. The patient’s initial hemoglobin and hematocrit levels are also considered when calculating how much blood loss they can tolerate.
The techniques used by the surgical and anesthesia teams can impact the amount of bleeding. The surgeon’s skill and operative approach contribute to how well bleeding is controlled at the source. Anesthesiologists can also employ strategies to help manage blood loss during the procedure.
Strategies for Minimizing Blood Loss
Surgical teams use a variety of tools and techniques to control bleeding in the operating room.
- Electrocautery is a device that uses a high-frequency electrical current to cut tissue or seal bleeding vessels with heat, allowing surgeons to stop small vessels from bleeding as they work.
- Pharmacological agents, such as tranexamic acid, are administered to prevent the breakdown of blood clots, which enhances the body’s natural clotting mechanisms and reduces the need for transfusions.
- Controlled hypotension is an anesthetic technique where the patient’s blood pressure is intentionally lowered during surgery, lessening the rate of bleeding from cut vessels and creating a clearer surgical field.
- Intraoperative cell salvage may be used when significant blood loss is anticipated. A machine collects the patient’s lost blood, which is then washed, filtered, and returned in a closed-circuit loop, reducing the need for donor blood.