What are the precautions when using a compression cuff?

There must be many people who don’t know about the tool called a cuff, but people who study medicine, especially nurses in hospitals, must be very familiar with this thing called a cuff. When nurses are giving patients infusions or injections, they need to find a vein on their hands. At this time, they need to use a rubber tube, which actually plays the role of a cuff. So what should nurses pay attention to when using a cuff?

Precautions for using a compression cuff:

The purpose of applying a compression cuff is to increase local venous filling and facilitate puncture. If the compression cuff is applied for more than 1 minute, the local blood oxygen content may decrease, lactic acid may increase, and pH may decrease.

If compression lasts for 3 minutes, bilirubin, cholesterol, AST, ALP, etc. can increase by more than 5%.

The correct operation is to first tighten the compression cuff and then observe the direction of the blood vessel, loosen the cuff in time, and then disinfect it. Then tighten the cuff again before puncture and draw blood immediately. Blood collection should be quick and blood should be drawn with one needle. This is especially important for specimens for coagulation testing, and it should be completed within 1 minute.

The compression time of the cuff should not be too long or too tight

Using a compression cuff for too long will obstruct blood flow and cause blood vessels to dilate, which will increase blood pressure in the capillaries and reduce blood flow, resulting in fluid loss. Continuous high vein pressure reduces the return of water and electrolytes to tissues, and increases the concentration of protein and protein complexes. Blood flow is obstructed, and fibrin activity increases. Cells continue to metabolize, which increases the metabolic product lactic acid. Therefore, the compression cuff should be used for less than 1 minute, and after the needle enters the blood vessel, it is advisable to relax the cuff.

When using a compression cuff, local ischemia (hypoxia) occurs, which will cause changes in the concentration of some components. For example, the concentration of BuN begins to decrease 80 seconds after the compression cuff is applied, and can decrease by 4% between 120 and 200 seconds, and returns to normal at 240 seconds. After tying the cuff for 3 minutes, the concentrations of ALB, Ca, ALP, AST, Fe, CHo, etc. can increase by 5% to 10%, respectively. The hypoxia caused by bandaging for 3 minutes is obviously more serious than that caused by bandaging for 1 minute. At this time, the anaerobic glycolysis of sugar increases, lactic acid increases, and the pH decreases. Calcium and magnesium ions are separated from the binding proteins and released. Similarly, the concentration of free drugs will also increase. Therefore, it is recommended to relax the cuff immediately after the needle punctures the blood vessel (<1 minute) to avoid blood stasis, intravascular hemolysis or changes in certain blood components. In particular, a cuff should not be used when measuring lactate.

If the tourniquet is not applied properly or is kept on for too long, water will be transferred from the blood vessels to the tissues, but large molecules and large particles (cells) cannot be filtered through, causing the blood to become concentrated. Experiments have confirmed that excessive tourniquet pressure or prolonged hemostasis can enhance fibrinolysis or accelerate platelet activation.