Lab

Objectives At the conclusion of this lesson, the nurse will be able to: Identify blood sample tubes and their use Describe proper use of Lab Requisition Form Describe common errors of lab specimen collection and transport "A lab test is only as accurate as the integrity of the specimen." General Information about Lab Testing   A standard panel of lab tests are done on all patients at screening after informed consent  is obtained for blood testing.  HIV testing requires a specific explanation and consent. All additional lab tests must be ordered by a doctor. Types of blood tests performed on board include: Hematology  Chemistry  Coagulation tests  Serology  Blood Bank to prepare whole blood for transfusion  Microbiology lab tests (including cultures and sensitivities to antibiotics) are also performed on urine, stool, sputum, blood and wound drainage specimens.   Blood samples are most often drawn by nurses and occasionally by lab technicians.  The following guidelines should be followed when drawing blood: All blood tubes should be filled to capacity, if possible Tubes should be mixed gently by inverting the tube several times IMMEDIATELY after drawing the sample to prevent clotting and ensure the blood mixes with the additives. Pediatric-size tubes and butterfly needles should be used for drawing blood on children. When drawing multiple tubes, the "non-additive" tubes  (red) should be drawn before others (blue, purple, green, gray, pink).   Standard Precautions should be followed and gloves should be worn when drawing blood samples. Needle protection devices should be used whenever possible.  Sharps should be immediately disposed of in appropriate sharps disposal containers.  IMMEDIATELY following any accidental needle stick, self first aid must be performed and the Charge Nurse, Nursing Supervisor/Ward Supervisor and Crew Physician/Duty Doctor must all be notified of the incident.  HIV prophylaxis is available but it must be started immediately to be effective. Blood Collection Techniques There are four techniques for collecting blood: Straight Vacutainer with needle protector Butterfly Vacutainer with needle protector Needle and syringe Lancet for fingerstick/heelstick There are three types of tubes: Regular sized blood tubes Pediatric sized blood tubes Microtainer tubes for fingerstick   Guidelines for handling specimens All specimens should be clearly labeled with the: Patient name and number Date, time, nurse initials Specimens should be taken to the lab in a plastic bag with a Lab Requisition Form                                  Click here to view  Lab Requisition Form Blood specimens should be refrigerated if they are not delivered to the lab within one hour of collection.   Specimens for culture should not be refrigerated and may sit at room temperature for a short period of time before they are put onto culture plates. Specimens should be collected and taken to the lab as early as possible in the morning.  There is usually only one lab tech on board at a time and this allows him/her to process the specimens during normal working hours.  If at all possible, do not collect specimens for culture on Thursday, Friday or Saturday as this will necessitate the lab tech working through the weekend to process the results. The lab technician can  be called or paged (during work hours) for questions. After work hours, a duty lab tech will have a beeper for emergencies Try to avoid calling tech during off hours if possible Charge nurses can plate cultures and do finger-stick Hemoglobin tests. Some charge nurses have been trained to do malaria smears, CBCs, HIVs, and Electrolytes after hours Click here to view  Hematology Report Special Considerations for Various Types of Blood Tests Performed Hematology   Use Purple top tube Tests include: CBC = Complete Blood Count DIFF= WBC Differential Malaria Smear (Lab or Charge Nurse can obtain) For CBC & Diff, fill Purple tube at least halfway & mix well IMMEDIATELY after drawing Remember that dehydration (which is a chronic condition in people from West Africa due to the unavailability or poor quality of good drinking water) may mask anaemia by artificially raising the Hgb/Hct levels.  It is common to see Hgb/Hct levels drop dramatically after the patient is hydrated with oral or IV fluids to reveal chronic anaemia. Use Red or Pink top tube Tests include: Electrolytes BUN and Creatinine Liver enzymes Glucose Cholesterol Cerebro-spinal fluid tests   Chemistry Coagulation Studies          Use Blue top tube but call the lab for special instructions BEFORE drawing specimen  Tests include: PT - protime PTT - active partial thromboplastin time If using a vacutainer, another tube of blood (preferably a red top) must be drawn before the Blue tube is filled Tube must be completely full for accurate results Use a Red or Pink top tube Tests include: HIV RPR - Syphilis Serum pregnancy tests Mono spot Rubella Surgeons will order specific patients to have HIV test at admission HIV testing is carefully regulated in each nation we visit A separate HIV consent form and specific HIV explanation is required before HIV testing is done Patients with positive HIV results are usually referred to their local health care system's HIV program for re-testing and counseling.  The positive results are not given on the ship. Serology   Blood Bank Use a Red and a Purple top tube, and special blood bank arm band and labels Tests include: Blood type Crossmatch Antibody screen Africa Mercy crew serve as a living blood bank and are screened by the crew clinic Patients normally receive blood in OR or Recovery Room Patients may have tubes already drawn for T&C (type and cross-match) - Call lab to see if patient’s blood is available before drawing another set Urinalysis Samples for urine cultures must be collected with clean catch-midstream technique or catheterization, with a minimum of 12cc, in a sterile urine cup Urine-based pregnancy tests, glucose, nitrites, specific gravity, protein, blood, etc. may be done with dipsticks on the ward.  A non-sterile collection cup may be used. Microbiology  Culture and sensitivity to antibiotics can be done on: Wound drainage Urine  Stool Sputum Blood When possible, collect cultures during day shift so they can be plated immediately When bacterial culturette swabs are used for specimen collection, the tube should be clearly labeled with: Patient’s name, number Date, time, nurse’s initials Source of sample (left foot, chin wound, etc.) After specimen is obtained, swab is placed back into the sterile tube and the tube is squeezed to break the preservative capsule in tube The sample should be left at room temperature and not refrigerated. The sample should be taken to the lab immediately. If lab tech is not available, a charge nurse may "plate" the specimen on petri dishes. Cultures are not considered 'STAT' or 'call-in'. If blood cultures are drawn, label and place them in 35' incubator and leave a note for techs. Common Errors of Blood Collection Problem:  Insufficient mixing of blood in tube Result: Platelet clumps or clots Problem:  Using wrong tube for the desired test Result: Delay in lab results, re-stick Problem:  Traumatic or difficult draw Result: Hemolysis (destruction of red blood cells) Problem:  Mislabeling or failing to label specimen Result: Possible error in report Problem:  Drawing from a vein above an IV Result: Diluted specimen, inaccurate results Problem:  Poor transport and storage of specimen Result: Inaccurate results Bedside Tests For OR/ICU use, we also have a Hemocue machine for measurement of hemoglobin, and an i-Stat portable analyser for blood gases and quick result-electrolytes. Cartridges for the i-Stat are expensive and should be used only for critical, ventilated patients. Pulse oximetry will generally guide ventilation changes. One-Touch II Glucose meter is also used for a variety of patients.  < Previous menu   /   ^Top   /   Next page >