This product was never used before. Recommended for training.
- Displacement of blood from the limbs to the central circulation (exsanguination).
- Blocking arterial blood flow into the limb (tourniquet).
- it brings the patient’s own blood with all of its clotting factors and intact oxygen-carrying capacity into the essential organs, and prevents the heart from having to provide blood flow to the limbs.
he effects of the EED on Left Ventricular and Arterial Pressures
The circulatory effects of application of the EED can be summarized by using the typical cardiac cycle diagram shown above. In this diagram the pressure inside the left ventricle axis is seen (in brown or gray) to increase rapidly at the beginning of the Systole, peak and then fall to near zero pressure. During the Diastole the ventricular pressure increases gradually as the ventricle fills with blood.
The pressure in the aorta and the large arteries follows the ventricular pressure once the aortic valve opens and the rapid ejection starts. The aortic pressure contintues to follow the ventricular pressure until the aortic valve closes. In normal circulation the aortic pressure falls gradually as more and more blood is supplied to the organs and tissues during the Diasotle (orange line in diagram). The rate of diastolic pressure fall is influenced by the resistance of the arteries and arterioles that lead to the organs and tissues. This resistance, called Systemic Vascular Resistance - SVR. The rate of diastolic pressure fall is also dependent on the cardiac output. If the cardiac output is low, or when the SVR is reduced as may happen in shock or during CPR, the pressure during diastole falls much faster than normal as shown by the light blue line.
Changes in the Diagram when the EED is used.
When the EED is used it pushes blood from the limbs (legs usually) to the center. This blood increases the venous return to the heart so that the filling of the left ventricle is improved and the ventricular filling pressure incline during Diastole is steeper (brown line marked as B). This increased ventricular filling increases the End-Diastolic Volume EDV of the ventricle, which, through the Frank-Starling mechanism, increases ventricular contractility, stroke volume and cardiac output. However, the EED has a second effect: it blocks the arterial flow into the limbs the EED is placed on. This effect of the EED impedes the flow out of the aorta to the limbs and has an immediate and direct effect on the SVR. Both effects (increased cardiac output and increased SVR) reduce the rate of fall of pressure in the aorta and main areteries during Diastole as shown schematically in the green line marked as A.
In summary, the overall physiological effects of applying the EED on a patient are:
1. Increased Venous Return to the heart
2. Increased Stroke Volume
3. Increased systolic blood pressure
4. Increased diastolic blood pressure
The use of the EED in Shock
Severe hemodynamic shock is characterized by poor tissue perfusion. This results in reduced organ (e.g. brain, heart, kidney, etc.) function and switch to unaerobic metabolism, acid formation and loss of arteriolar tone. When this happens the arterioles and veins dilate and blood pools in the periphery which further reduces blood pressure and cardiac output.
There are several categories of Shock:
1. Hypovolemic shock where blood volume is lower than normal (bloodloss, dehydration, diarrhea (cholera))
2. Distributive shock where the total volume of the circulation is larger than normal (septic, anaphylactic, neurogenic, toxic)
3. Pump failure shock where the heart fails to pump blood into the circulation (cardiogenic)
4. Obstructive shock where blood flow into the right or left ventricles is impeded (cardiac tamponade, pulmonary emboli, pneumothorax)
The EED is indicated for use in severe shock of categories 1 and 2. It is not currently recommended for categories 3 and 4.
In addition to the standard treatment (fluids, blood, vasoactive drugs, supportive measures), apply EED to one leg and measure blood pressure. If the systolic blood pressure continues to be pathologically low (e.g. below 80 mm Hg) , apply second EED to other leg. In patients who have uncontrolled bleeding (e.g. intra-abdominal hemorrhage), the systolic blood pressure should be kept between 80 to 100 mm Hg or as instructed by a physician (see Blood Pressure Titration by the EED paragraph below). In other types of shock the systolic blood pressure may be allowed to exceed 100 mm Hg.
Blood Pressure Titration by the EED
Rolling the EED up a limb increases the blood pressure. Rolling it down will reduce systolic blood pressure. Rolling is done by manually rolling the ring down the limb (picture). it should be done in small steps of about 15 cm (6") each. After each step, the blood pressure of the patient should be measured. If the blood pressure falls to less than 80 mm Hg, or other symptoms of hemodynamic instability (e.g. excessive tachycardia, cognitive deficit) are seen, consider bringing the EED back up. This should be done by pulling the straps as in the first application of the device.
Marking placement time and removal time
The EED should not be left on a limb for more than 120 minutes (two hours). In order to verify, it is important to mark the time of applying the EED on each limb very clearly using adhesive tape or stickers (see picture).