One of the most common procedures children undergo is a venipuncture for a blood sample. Recently, I have questioned a number of variables that affect the trauma of having a venipuncture. One of these factors is the size of the needle that can be used to obtain blood. I initially became interested in this question because phlebotomists at some hospitals stated that the smallest gauge that they could use to draw blood was 23. I knew that this was incorrect since blood is often drawn using a 25-gauge needle. However, since the size of the needle is directly related to the pain from the needle puncture, I began to question if smaller gauge needles could be used. I was unable to find anything from a literature search that confirmed that 27-gauge needles or smaller could be substituted. (If you are unconvinced about the difference needle size can make, compare 23-, 25-, and 27-gauge needles to appreciate the different widths.)
However, one phlebotomist, who has been extremely concerned with preventing trauma in children from venipunctures, agreed to do a small pilot study using 27-gauge needles to draw blood. Although her sample size is only 10 children, these are her findings: there is no difficulty drawing blood with a 27- gauge needle provided a small amount of blood, 1 to 1 ½ ml, is needed. This small amount of blood is sufficient for many routine tests performed on a blood sample in microtainers. Some of these tests are Chem7,12, etc., K+, glucose, drug levels, and so on. Blood must be withdrawn carefully to avoid excessive pressure, which could hemolyze the cells. Children reported that the 27-gauge needle caused almost no pain; an additional benefit may be less scarring of the vein. The 27-gauge needle has a length of one-half inch and is appropriate only for prominent veins. She has been so impressed with the patients' reaction to having blood draw with this small needle and no reports of hemolysis, that she is planning a controlled study that will include complete blood counts. Since a monocyte is the largest blood cell, it might be damaged by the small gauge needle, which could alter the WBC. If that study is successful, she will then try a 29- and 30-gauge needle.
I have also contacted different children's hospitals to ask about their use of 27-gauge needles and have found two neonatal intensive care units that are using or have used this size in the infants. Both report no difficulty drawing blood, no incidence of hemolysis, and possibly less pain inflicted on the infant. One of the NICUs no longer uses the 27-gauge size (uses 25 gauge) because the hospital no longer purchases this item.
Another issue that I have investigated is the length of time that blood can be saved by the lab for additional testing. In my clinical experience, it is not unusual for a child to have more than one blood draw within a short period of time, because new orders are written for blood tests. Again the phlebotomist has informed me that at her institution, blood is routinely kept for one week, and their reference department has been known to keep children's serum even longer. Numerous tests can be performed on a saved serum sample. Since the volume of blood drawn on very young children must not be excessive, the phlebotomist must know in advance that additional blood should be saved for testing.
This phlebotomist, from Tulsa, Oklahoma, describes her experience with a child, who over the course of a few days, needed numerous blood tests, some of which were done from the saved blood.
A 13-month-old, white male developed upper respiratory symptoms. He was taken to the doctor and diagnosed with acute otitis media and treated with antibiotics. That night and the next morning, the child had decreased oral intake, decreased urine output, and decreased level of activity. He was again taken to the doctor, who admitted him to the hospital with dehydration. After treatment for the dehydration, the patient was not improving and developed a petechial rash. He was transferred to Pediatric Intensive Care Unit.
Initial lab work included a DIC (disseminated intravascular coagulation) profile (pt,ptt, fsp, and fibrinogen with a CBC), a blood culture, and chemistry. Since this initial lab work required 7.6 ml of blood, no extra blood was saved. The next morning, a repeat DIC profile was ordered. The mother was quite upset because her child "had been stuck several times and the doctor finally had to get the blood sample." The child's extremities were edematous, capillary refill was 4-5 seconds, and the skin was cool to the touch and slightly mottled with a petechial rash. Emla had been applied to both antecubital areas about 1 ½ hr. earlier; a vein was accessed on the first attempt with a 23g. butterfly needle and a 5cc syringe. Although only 3.2 ml of blood was needed for the tests ordered, 5 ml were drawn and the balance saved as a hold tube. Later, a repeat blood culture was ordered and 6 ml of blood drawn, with 2 ml placed in a pediatric blood culture bottle and the balance in a red-top tube to hold.
The next morning titers for Rocky Mountain spotted fever, tularemia, and Erlichia were ordered. Because of the "hold" blood that had been drawn over the last two days, the tests were done using saved blood.
Many ways exist to provide atraumatic care to children and reducing stress for any type of blood vessel puncture. A very simple intervention is to keep all the equipment covered until it is needed. Young children have the concept of animism, which means that they attribute life-like qualities to inanimate objects. Therefore a toddler or early preschooler who sees a syringe on a table believes that it has the power to move on its own and strike the child. Therefore, "out of sight" often means "out of mind". This phlebotomist has ingeniously created a movable "train engine" that is her phlebotomy cart. It houses all of the phlebotomy equipment and a smoke stack which stores small donated gifts (from staff at the hospital and some former patients) that are given to the children after the procedure. Of course, the gifts are given regardless of the child's degree of cooperation. The train has proved to be a wonderful addition to the children's hospital. When children see the train, they do not immediately react with fear but more with anticipation of the "treats" that come from the train. And the train has been rumored to have had a passenger or two around the halls of pediatrics! While the train is an elaborate method of keeping the equipment out of sight, simpler methods such as covering the carrying box for the supplies with a decorative piece of fabric are also effective.
Of course, this phlebotomist strongly advocates for all children to have EMLA applied whenever possible. When the use of EMLA is not possible, the use of fluori-methane spray and a 25- or 27-gauge needle have minimized the child's distress. She has had no problems with vein constriction with the cooling spray but cautions that the cannulation must be very quick since the numbing effect of the spray is only a few seconds. On the few occasions that vein constriction may have occurred with EMLA, a hot-pack applied to the site quickly dilates the vein, and some patients believed that the heat enhanced the effect of EMLA.
Whatever method is used, the parents or staff members can overcome children's pain and learned fears and greatly enhance their positive health care experiences. As health care professionals, we have two choices: help the child get through an unpleasant experience with minimal distress, or set the stage for perpetuating the child's stress by creating a combative and terrified child. The choice is ours.
March 15, 2002
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