Venipuncture Procedures

Transcription

1 Venipuncture Procedures C/E Update: by Jean M. Slockbower, Ph.D. Special Topics I Category A-1 continuing education credit is available to anyone who studies a C/E Update series and completes a written exam. Exams can be ordered from the ASCP and will be sent to participants following the appearance of the final article of each series in LABORATORY MEDICINE. After receipt of a completed answer sheet at ASCP prior to the deadline stated on the exam, a certificate of credit will be awarded to each participant. An exam order form appears on page 768 in this issue. Introduction Jean M. Slockbower, Ph.D., is with the Department of Laboratory Medicine at the Mayo Clinic and Mayo Foundation in Rochester, Minnesota, and Chairholder of the Subcommittee for the Standardization of Blood Collection Procedures in Hematology, Biochemistry and Serology of the National Committee for Clinical Laboratory Standards, Villanova, Pennsylvania. This article is based on standards developed by the Subcommittee for the Standardization of Blood Collection Procedures in Hematology, Biochemistry and Serology, one of many subcommittees of the National Committee for Clinical Laboratory Standards (NCCLS). The NCCLS develops and publishes voluntary laboratory standards in an effort to avert regulation imposed by external agencies. The idea for an independent voluntary consensus standards organization was proposed by the Standards Committee of the College of American Pathologists. M u c h is made of the necessity for accurate and precise methodology in the laboratory, yet not enough attention has been devoted to the establishment of quality control measures to be followed when collecting and handling a blood specimen. Proper specimen collection and specimen handling are of the utmost importance, for today the likelihood of error occurring in these areas is probably greater than the likelihood of error occurring in the laboratory procedure itself. Studies have indicated that 8% of errors that are made in patient name, age, sex and identification number are undetected despite extensive manual checking procedures. 1 It is hoped that biologically representative patient specimens for laboratory testing can be obtained as individuals develop procedures in their own institutions utilizing the NCCLS standards for b l o o d collection. 2-4 Facilities and Supplies A well-planned, attractive environment in w h i c h to perform venipunctures can reduce patient anxiety while increasing efficiency and accuracy on the part of the venipuncturist. The venipuncturist needs a complete assortment of equipment available for use so that the most appropriate materials for each individual patient can be judiciously selected. Venipuncture Procedure Performance of the venipuncture procedure requires both knowledge and skill. The trained venipuncturist must execute the f o l l o w i n g basic steps when drawing a blood specimen: Assign an accession number. Identify the patient. Check the patient's diet restrictions. Reassure the patient. Position the patient. Assemble supplies. Verify accuracy of paperwork and tube selection. Close the patient's hand. Select the vein site. Cleanse the venipuncture site. Apply the tourniquet. Inspect the needle and collection tube or syringe. Grasp the patient's arm. Perform the venipuncture. Release the tourniquet. O p e n the patient's hand. Position the gauze pad. Remove the needle and apply pressure. Bandage the arm. Copyright 1979 Mayo Foundation Downloaded from 747

2 Fill the tubes if syringe and needle are used. Dispose of the. puncturing unit. Chill the specimen if necessary. Eliminate the patient's diet restrictions. Record the date and time of venipuncture. Send blood samples to the proper laboratories. 1. Assign Accession 4. Reassure the Patient The venipuncturist must gain the patient's confidence. The patient should be t o l d that the venipuncture will be slightly painful but of s h o r t d u r a t i o n. Patients should never be t o l d, "This w o n ' t h u r t. " 5. Position the Patient Number Each request for a blood specimen must be accessioned in order to provide a means of identifying all paperwork and supplies associated w i t h each individual patient. "Accessioning" is the act of assigning a number (known as the accession number) to all collection tubes and laboratory forms relating to a specific specimen. Every institution in which venipunctures are performed needs an organized system to insure that the various forms used in performing a venipuncture and in analyzing and reporting test results are processed promptly and accurately. The patient should be seated comfortably in a chair with arm extended on the slanting armrest to f o r m a straight line from the shoulder to the wrist. The arm and elbow should be supported firmly by the armrest and should not be bent at the elbow. If hospitalized, the patient may lie on his or her back in a comfortable position. Place a pillow under the arm f r o m which the specimen is being drawn if additional support is needed. Again, the patient's arm should be extended to form a straight line from the shoulder to the wrist. 6. Assemble Supplies 2. Identify the Patient Identification of the patient is crucial to insuring that the blood specimen is being drawn from the individual designated on the request f o r m. Ask the patient to give his or her full name and address. Compare this information with the information on the request form and the patient's identification bracelet. Report any discrepancy, however minor, to the appropriate person and have that person identify the patient by name and identification number before drawing any specimen. If the patient is unconscious, very young, deaf, or unable to speak the language of the venipuncturist, a nurse, relative or friend should be asked to identify the patient by name, address and identification number. Identification standards established by the American Association of Blood Banks provide clear guidelines to be used when collecting blood specimens from unidentified emergency patients: "The patient must be positively identified when the blood specimen is collected. The unidentified emergency patient should be given some temporary but clear designation until positive identification can be made. In all cases, the name and hospital number of the emergency identification should be attached to the patient's body either by wristband or some similar device." 5 3. Check the Patient's Diet Restrictions Ask the patient if he or she has followed diet restrictions if specimens are for tests which require the patient to fast or to eliminate certain foods f r o m the diet prior to the blood collection. Assemble the necessary supplies for the venipuncture. The type of needle chosen should be based on the patient's physical characteristics and the amount of blood needed. The appropriate system to be used for drawing the blood specimen should be selected. Generally, a syringe is used only when drawing a specimen f r o m individuals w i t h fragile, thready or " r o i l y " vein walls. The evacuated tube system is the most commonly used means of collecting specimens. This system is generally preferable to the needle and syringe since it allows the blood to pass directly from the vein into the evacuated t u b e. The system is composed of three basic elements: a sterile blood collection needle, a holder that is used to secure both the needle and evacuated tube, and an evacuated tube containing a premeasured vacuum and in some cases a premeasured additive. Refer to NCCLS Standard ASH Verify Accuracy of Paperwork and Tube Selection Check paperwork and collection tubes to insure that no mistakes have been made in labeling or in selection of appropriate tubes. The color-coded tube stoppers and labels facilitate the performance of this step. 8. Close the Patient's Hand Ask the patient to close his or her hand so that the veins will become more prominent and thus easier to enter. Vigorous hand exercise or " p u m p i n g " should be avoided. 9. Select the Vein Site Selection of vein site is very important because a patient's life may depend on vein patency. The larger LABORATORY MEDICINE VOL. 10, NO. 12, DECEMBER 1979 Downloaded from

3 and fuller median cubital veins (superficial veins of the anterior surface of the upper extremity) are used most frequently; however, wrist and hand veins are also acceptable for venipuncture. than one m i n u t e ; to do so may result in either hemoconcentration orvariation in bloodtestvalues. 6 The following factors should be considered in site selection: Inspect the tip of the needle visually to determine if it is free of hooks at the end of the point, and if its opening is clear of any small particles that w o u l d obstruct the flow of b l o o d. a. Extensive scarring. Healed burn areas should be avoided. b. Mastectomy. Because of lymphostasis resulting from mastectomy, specimens should not be taken from the side on which a mastectomy was p e r f o r m e d. c. Hematoma. Specimens collected from an area of hematoma may yield erroneous test results. If another vein site is not available, the specimen should be collected distal to the hematoma. d. Intravenous (IV) therapy. Specimens should be collected from the arm not involved in intravenous therapy. If this should prove impossible, the attending physician should be consulted. The IV should be turned off for at least two minutes before venipuncture is performed on the arm involved in IV therapy, and the site chosen should be below the IV entrance. Use the following procedure for vein selection: Palpate and trace the path of veins several times with the index finger. (Unlike veins, arteries pulsate, are more elastic, and have a thick wall. Thrombosed veins lack resilence, feel cordlike, and roll easily.) If superficial veins are not readily apparent, blood can be forced into the vein by gently massaging the arm from wrist to elbow. Several sharp taps at the vein site with index and second finger will cause the vein to dilate. Application of heat to the site may have the same result. Lowering the extremity over the bedside will allow the veins to fill to capacity. 10. Cleanse the Venipuncture Site The venipuncture site must be cleansed to prevent any chemical or microbiologic contamination of either the patient or the specimen. Usually, the vein site is cleansed with 70% isopropyl alcohol solution on a gauze pad, using a circular motion from the center of the site to the periphery. Allow the area to dry in order to prevent hemolysis of the sample and a burning sensation to the patient when the venipuncture is being performed. 11. AppJy the Tourniquet A tourniquet allows the veins to fill with b l o o d, thus making the veins more prominent and easier to enter. Do not leave the tourniquet on for longer 12. Inspect the Needle and Syringe If using a syringe, move the plunger within the barrel to demonstrate syringe and needle patency and freedom of plunger movement. 13. Grasp the Patient's Arm The patient's arm should be grasped firmly, using the t h u m b to anchor the vein by drawing the skin taut. 14. Perform the Venipuncture a. Venipuncture procedure using needle and syringe: 1) Place the patient's arm in a downward position if possible. 2) Line up the needle and syringe with the vein from which the blood will be drawn. 3) Turn the needle so that the bevel side is in an upward position. 4) Push the needle into the vein. A sensation of resistance will be felt, followed by ease of penetration as the vein is entered. 5) Withdraw the desired amount of blood into the syringe. 6) If additional blood is needed, replace the first syringe with another; the needle should remain in the vein while this is done. Slip a clean dry gauze pad under the needle to catch the blood while changing syringes. b. Venipuncture procedure using evacuated tubes: 1) Thread the appropriate needle into the holder until it is secure, using the needle sheath as a w r e n c h. 2) Use a sterile blood collection t u b e. Tap all tubes that contain additives before use to insure that all of the additive is dislodged from the stopper and wall of the t u b e. 3) Push the stopper of the blood collection tube into the needle within the holder up to the recessed guideline on the needle holder. Do not push the tube beyond the guideline as a premature loss of vacuum may result. 4) If possible, make sure that the patient's arm or other venipuncture site is in a d o w n ward position and maintain the tube below the site throughout the procedure. This will LABORATORY Downloaded from MEDICINE VOL, 10, NO. 12, DECEMBER

4 5) 6) 7) 8) 9) 10) 11) insure that any backflow from the tube will not go into the patient's vein. Push the needle into the vein. Grasp the flange of the needle holder and push the tube forward until the butt end of the needle punctures the stopper, exposing the full lumen of the needle. Remove the tourniquet as soon as blood flow is established. Once the b l o o d begins flowing, do not change the position of the tube until it is withdrawn from the needle. Maintain constant but slight forward pressure (in the direction of the needle) on the end of the tube. This prevents release of the shutoff valve and stoppage of b l o o d flow. Do not vary pressure nor reintroduce pressure after completion of the blood draw. Allow the tube to fill until vacuum is exhausted and blood flow ceases in order to insure the correct ratio of anticoagulant to b l o o d. The tube normally will not be filled completely. When the blood flow ceases, remove the tube f r o m the holder. If a multispecimen needle is used, the shutoff valve re-covers the butt end of the needle, stopping blood flow until the next tube is inserted. After drawing each tube that contains an additive, mix immediately by gently inverting the tube five to ten times. To avoid hemolysis, do not mix vigorously. To obtain additional specimens, insert the next tube into the holder and repeat the procedure. 19. Bandage the Arm Apply an adhesive or gauze bandage over the venipuncture site. Tell the patient to leave the bandage o n for 15 minutes. If the patient continues to bleed, apply pressure to the site with a gauze pad until the bleeding stops. 20. Fill the Tubes if Syringe and Needle are Used Fill appropriate collection tubes. If evacuated tubes are used, the stoppers should not be removed. Puncture the diaphragm of the rubber stopper on the appropriate tube with the syringe needle, and allow the correct amount of b l o o d to flow slowly into the tube. Never force blood into a tube. 21. Dispose of the Puncturing Unit Needles should be disposed of promptly to prevent their reuse and to prevent any personnel f r o m being injured accidentally. Use a needle cutter to cut off the t i p, or insert the needle back into its shield and discard it in a box designated and appropriately labeled for this purpose. 22. Chill the Specimen if Necessary Some tests require that blood specimens be cooled in ice water immediately following the venipuncture in order to slow d o w n metabolic processes w h i c h may cause alteration of some chemical values. 23. Eliminate the Patient's Diet Restrictions If the patient is hospitalized, remove the patient's name f r o m the " h o l d breakfast" list. 24. Record the Date and Time of Venipuncture 15. Release the Tourniquet Remove the tourniquet as soon as blood flow is established. Tourniquet release allows the blood circulation to return to normal and also reduces bleeding at the venipuncture site. 16. Open the Patient's Hand Ask the patient to open his or her hand after enough blood has been collected; this reduces the amount of venous pressure. Once the blood sample has been drawn, the venipuncturist should record the date and time that the venipuncture is completed. Data necessary for permanent record includes the m o n t h, day, year and time. Consideration should be given to additional comments useful for laboratory personnel or the physician, such as IV, nonfasting, etc. 25. Send Blood Samples to the Proper Laboratories 17. Position the Gauze Pad Send blood sample tubes to the appropriate laboratories designated to perform the required testing procedures. Lightly place the gauze pad above the venipuncture site. Venipuncture in Children 18. Remove the Needle and Apply Pressure Apply slight pressure to the gauze pad. Remove the needle slowly while keeping the bevel in an upward position. Exercise care not to scratch the patient's arm. Slip the gauze pad d o w n over the site, continuing mild pressure. If a venipuncture is performed on a child under two years of age, the site should be limited to superficial veins (i.e., the femoral vein is not recommended). Venipunctures should be performed with either a tuberculin or a 3-ml syringe w i t h a 21- or 23-gauge needle, or a 20- to 23-gauge butterfly needle with attached t u b i n g, or a butterfly LABORATORY MEDICINE VOL. 10, NO, 12, DECEMBER 1979 Downloaded from

5 needle and t u b i n g attached to a vacuum tube holder. When possible, microspecimens should be collected by skin puncture. Additional Considerations 1. Prevention of Hematoma a. Puncture only the uppermost wall of the vein. b. Remove the tourniquet before removing the needle. c. Use only the major veins, not superficial veins. d. Make sure that the needle fully penetrates the uppermost wall of the vein. Partial penetration may allow blood to leak into the soft tissue surrounding the vein by way of the needle bevel. e. Apply a small amount of pressure to the area with the gauze pad when bandaging the arm. 2. Prevention of Hemolysis a. Mix anticoagulated specimens thoroughly by inverting each tube gently five to ten times. b. Avoid drawing blood from an area of hematoma. c. Avoid drawing the plunger back too forcefully when using a needle and syringe. d. Avoid using a needle that is too small. e. Make sure that the needle is fitted securely on the syringe to avoid frothing of the b l o o d. f. Ascertain that the venipuncture site is dry w i t h out touching it. g. If a sterile glass syringe is used, it must be dry. 3. If a Blood Sample is Unobtainable a. Change the position of the needle. If the needle has penetrated too far into the vein, pull it back a bit. If it has not penetrated far e n o u g h, advance it farther into the vein. Rotate needle a half t u r n. b. Try another t u b e ; the tube may not have any vacuum. c. Loosen the tourniquet. It may have been applied too tightly, thereby stopping the blood flow. Reapply the tourniquet loosely. This procedure can be accomplished easily when using the velcro-type tourniquet by releasing it and quickly pressing it together again. d. Probing for the vein is not recommended as it is painful to the patient. In most cases, another puncture in a site below the first site is advised. e. Never attempt a venipuncture more than twice. Request that another person attempt to draw the specimen or notify the physician. Special Situations 1. Timed Intervals Some specimens must be drawn at timed intervals because of medications or biologic variations (cir- cadian rhythms). It is important that specimens for timed tests be obtained at the precisely specified interval and that specific directions to that effect be given to the venipuncture team. Examples of tests r e q u i r i n g t i m e d specimens are: a) tests where diurnal or other time effects may be anticipated, such as corticosteroids, serum iron and glucose tolerance, and b) therapy-monitoring tests, such as prot h r o m b i n time, APTT, salicylic acid and digoxin. In these cases, the dose of the medication and the time of the specimen collection should be recorded accurately on the request slip or in the laboratory computer system. 2. Specific CoJiection Techniques Specific techniques and systems should be developed by laboratories for collection of blood specimens for alcohol, heavy metals, and legal studies. 3. The Isolated Patient Patients are isolated for two reasons: to prevent the disease from spreading to other patients, relatives and employees, and to protect the patient from outside contamination. In the latter case, the patient's normal protective mechanism has been reduced to such a point that infection could be fatal. The isolation system makes use of a color-coded card that is placed on the door or w i n d o w of the patient's r o o m. The card describes the type of isolation and the precautions that must be taken by those entering the r o o m. There are five types of isolation: strict, respiratory, w o u n d and skin, protective, and enteric. Before entering the isolation r o o m, one should read the isolation sign on the d o o r ; it will explain the type of isolation and what must be w o r n and done. Follow these instructions carefully. Check your orders and assemble the equipment needed for the patient. Take in the m i n i m u m equipment needed. Remember that anything taken into the room must be left there, discarded, or cleansed carefully if taken f r o m the r o o m. 4. Prevention of Hepatitis and Other Infections Hepatitis is classified into t w o types, each caused by a different virus: type A or infectious hepatitis, and type B or serum hepatitis. The viral agents may be present in all body fluids, including urine and intestinal contents. The patient known to have infectious hepatitis is placed in enteric isolation during the acute phase of the disease. All laboratory requisitions must indicate that the patient is infected with hepatitis. All laboratory specimens must be labeled clearly as coming f r o m a patient with hepa- LABORATORY Downloaded from MEDICINE VOL. 10, NO. 12, DECEMBER

6 titis. Blood collection techniques should be evaluated carefully to minimize risk to the laboratory staff: a. Observe aseptic blood-drawing techniques. b. If the outside of the tube is contaminated with b l o o d, the tube should be wiped with disinfectant before further handling or transfer. c. All needles and syringes used should be discarded in a suitable container. d. Wash hands thoroughly between patients. serve as a public relations ambassador for the Department of Laboratory Medicine, as this may be the only contact the patient has with the laboratory. References 5. Doctor/Patient Relationship The doctor has priority in seeing the patient. The venipuncturist should not enter the room while the doctor is visiting the patient, but rather should come back at another time. However, if the order is a Stat order, the venipuncturist should ask politely if the physician w o u l d like the blood sample drawn now or at another time. Training Program W i t h o u t question, a sound training program is needed to produce efficient, well-trained venipuncturists. After proper training, the venipuncture trainee should be able to perform the following tasks: 1. Explain the physical layout of the laboratory blood drawing area and the hospital floors. 2. Identify the various pieces of equipment used in the venipuncture procedure and describe how each is used. 3. Identify the various request forms associated with the venipuncture. 4. Identify the veins normally used in performing a venipuncture. 5. Perform a venipuncture on a simulated arm. 6. Perform the basic steps comprising the venipuncture procedure. Particular emphasis is placed on the procedures used for identifying patients by alphabetical and numerical characters. Summary It is hoped that once the venipuncturist has mastered these tasks, he or she will have acquired a professional attitude and bedside manner. The manner in which the venipuncturist approaches the patient may have a direct bearing on the patient's response to the venipuncture. Emphasis should be placed on the need for a pleasant bedside manner. The venipuncturist should identify himself or herself and explain the procedure to the patient. The venipuncturist must gain the confidence of the patient, reassure the patient, and try to relieve any apprehension the patient may feel. The venipuncturist should LABORATORY MEDICINE VOL. 10, NO. 12, DECEMBER 1979 Downloaded from 1. Taswell, H.F., et al., 1974, Quality control in the blood bank A new approach. Am. J. Clin. Pathol. 62: NCCLS Subcommittee for the Standardization of Blood Collection Procedures in Hematology, Biochemistry and Serology, ASH-1 Standard for Evacuated Tubes for Blood Specimen Collection, Villanova, Pa,, National Committee for Clinical Laboratory Standards. 3. NCCLS Subcommittee for the Standardization of Blood Collection Procedures in Hematology, Biochemistry and Serology, 1979, TSH-3 Standard Procedures for the Collection of Diagnostic Blood Specimens by Venipuncture. Villanova, Pa., National Committee for Clinical Laboratory Standards. 4. NCCLS Subcommittee for the Standardization of Blood Collection Procedures in Hematology, Biochemistry and Serology, TSH-4 Standard Procedures for the Collection of Diagnostic Blood Specimens by Skin Puncture. Villanova, Pa,, National Committee for Clinical Laboratory Standards. 5. Technical Methods and Procedures of the American Association of Blood Banks, th edition. Washington, American Association of Blood Banks. 6. Gerbrandy, J., et al., The binding between electrolytes and serum proteins calculated from an in vivo filtration method. Clin. Sci. 19:181. Review Questions Special Topics I 1. List four factors that should be taken into account when selecting a venipuncture site. 2. Describe the procedure that should be followed if a blood sample must be obtained from an arm involved in IV therapy. 3. State the reason for performing each of the following procedure steps when obtaining blood samples using the evacuated tube system: a. Tap blood collection tubes that contain additives before use. b. Maintain the collection tube in a position below the venipuncture site throughout the procedure. c. Maintain slight but constant pressure on the end of the collection tube in the direction of the needle while obtaining the sample. 4. Describe the procedure for the proper disposal of the puncturing unit. What additional precautions should be taken if contamination with hepatitis virus is suspected? 5. List at least three important considerations that should be observed when obtaining a blood sample from a child under two years of age. 6. Describe the procedures that should be followed when performing a venipuncture on a patient in isolation. Self-assessment exam order form can be found on page 768.