Blood Infusion
Needle size depends on the size and integrity of a patient's vein. An 18-gauge needle is standard, but a needle or catheter as small as 23-gauge can be used for transfusion if necessary. The smaller the gauge, the slower is the flow rate and the higher is the risk of clotting. Care must be taken to avoid excessive pressure and resulting hemolysis when very narrow devices are used. Diluting red cells with saline or asking the Transfusion Service to split a unit and giving only half at a time may help if the flow rate is too slow.
Leukocyte Removal Filters
Special bedside filters may be provided by the Transfusion Service when pre-storage leukocyte-reduced red cells or platelets are not available. Red cell and platelet filters do not use the same technology for leukocyte removal and are not interchangeable. Some are designed to attach to standard infusion sets; others come with a set already attached. Most leukocyte-removing filters are designed for gravity drip use and have special priming requirements, so it is essential to check the manufacturer's directions before use.
IV Pumps
Mechanical pumps may be useful for controlling the very slow infusion rates required by neonatal and pediatric patients, but care is needed to avoid hemolysis. Only pumps specifically approved for blood transfusion should be used. Some pumps can be used with standard infusion sets; others require special software.Pressure Bags
Pressure bags are needed only in emergency situations when blood must be transfused rapidly, such as 5 minutes per unit. The bag should be inflated only until blood flow through the drip chamber is continuous, about 200 mm Hg. Pressure approaching 300 mm Hg may cause the red cells to Iyse and the blood bag seams to split.
Blood Warmers
Blood warmers are used to prevent cardiac arrhythmia associated with the rapid infusion of large volumes of cold blood. Specific indications include:
- Adults receiving blood at a rate in excess of 100 mL per minute
- Children receiving blood over 15 mL/kg/hour
- Patients with clinically significant cold agglutinins
- Rapid infusion of blood through central lines
Blood should not be warmed to a temperature that causes hemolysis. Only temperature-controlled and monitored in-line devices are acceptable for use, and some require special software. The blood warmer must have a visible thermometer and, ideally, an audible alarm. The warmer should be set up according to the manufacturers' directions and its temperature checked periodically during use.
IV Solutions and Medications
Normal Saline (0.9% sodium chloride) can be added to blood, but drugs and medications must never be added. Compatible plasma or 5% Albumin can be added to blood following approval by the patient's physician. Isotonic electrolyte solutions that do not contain calcium may mix with blood if the FDA approves the solution for such use or if there is adequate documentation of safety. Some solutions should not contact blood in the bag or tubing. Solutions containing glucose (e.g. 5% dextrose) may cause red cells to aggregate and Iyse and those containing calcium (e.g. Ringer's Lactate) may cause blood to clot.
Infusion Rates
Packed red blood cells can be diluted with 0.9% NaCl to decrease viscosity and improve flow rate. Adsol units usually do not require further dilution, because they have already been diluted by the addition of preservative. Red cells should be infused through an IV catheter and a standard 170 micron filter at a rate of 2 mL/minute for the first 15 minutes. The recipient should be observed for evidence of a transfusion reaction during this time period. If no adverse effects occur, the rate can be increased to 4 mL/minute for nonemergent transfusions. An infusion rate of 17mL/min allows an entire unit of blood to be transfused in 30 minutes. The usual recommended time period ranges between 1.5 and 2 hours per unit. The maximum time period allowed for infusion of a single unit of blood is 4 hours. In emergency situations, the infusion rate is not as well established. Infusion rates greater than 60mL/min are dangerous and infusion rates greater than 100mL/min are associated with cardiac arrest. External pressure devices can be used to increase the rate of infusion. The pressure exerted should not exceed 300 mm Hg. Blood pressure cuffs should not be used because they apply pressure non-uniformly and can cause leakage.
Platelets are transfused through platelet filters at a rate which allows a pool of random donor platelets or a single donor platelet to be transfused within 30 to 60 minutes. FFP is usually transfused through a standard blood filter at a rate of 30 to 60 minutes per bag. Cryoprecipitate is infused through a standard blood filter at a rate of 4 to 10 mL/minute. At this rate, a pool of 10 bags can be infused in approximately 30 minutes.
Transfusion Delays
If the start of a transfusion is delayed after a unit of Red Blood Cells has been issued, the unit can be returned to inventory if it has not remained at room temperature for more than 30 minutes. The Red Blood Cell unit's temperature will usually not exceed 10o C for at least the first 30 minutes at room temperature. If a unit remains at room temperature for longer periods of time, glucose and ATP might become depleted and any contaminating bacteria might begin to proliferate.
