Session Number 208 LAB POTPOURRI WHAT EVERY CRITICAL CARE NURSE NEEDS TO KNOW ABOUT COMMON LABS

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1 Session Number 208 LAB POTPOURRI WHAT EVERY CRITICAL CARE NURSE NEEDS TO KNOW ABOUT COMMON LABS Content Description Hank Geiter, RN, CCRN-CMC Owner: Critical Care Transport RN: Sunstar EMS Although clinical assessment is the mainstay of the critical care nurse's detective work in determining what is going on with the critically ill patient and what they need; batteries of laboratory tests are run on these patients daily and hold a wealth of complementary information. In addition to guiding clinical assessment focus and frequency, as in the case of sodium or bicarbonate levels, they can also tell us about the patient's metabolic state (ph, pco2, lactate), whether they are dehydrated or in renal failure (BUN/creatinine ratio), what potential diagnoses may be responsible for the patient's acidosis (anion gap/mudpiles), and what other conditions may be present that are not revealed on clinical assessment... YET, and much, much more! Also, there is other important information regarding these tests that the critical care nurse needs to know. Proper collection, who do we run tests on (besides cost is there any other reason we don't run tests on everyone), and what are the tests' limitations (specificity vs. sensitivity, positive predictive value vs. negative predictive value) and more. What constitutes normal and how does the lab determine the normal range for a given test? Are all normal ranges the same? What about the effects of one value on another. Many nurses already know the relationship between magnesium and potassium. - but, what about calcium and albumin? What does the CO2 in the chemistry panel really measure (hint - the answer is not really CO2)? Beside blood tests, there are other tests that are done less frequently but are equally important. The results of these "low use - high value" tests can help the critical care nurse understand when an assessment finding is expected and benign or is critical. Join us as we cover common blood and body fluid (urine, CSF and pleural fluid) tests ordered in critically ill patients, what they test for and their implications to nursing care and assessment using an interactive case study approach. Learning Objectives At the end of this session, the participant will be able to: 1. Discuss factors that affect lab ordering, collection, testing, and interpretation. Henry Geiter, Jr, RN, CCRN-CMC 1 Common Labs, Uncommon Knowledge

2 2. Describe the relationship between diagnostic exams and the diagnosis and treatment of patients 3. Discuss common blood tests, what they are testing for, limitations and at least two diagnoses associated with abnormalities in each component 4. Discuss common body fluid tests, what they are testing for, limitations and at least two diagnoses associated with abnormalities in each component Outline I. Introduction A. Why Do Lab Analysis? 1. Establish baseline data 2. Observe trends and changes over time 3. Provide support in the diagnosis of disease 4. Aid in determining the acuity B. General Guidelines 1. Right specimen in the right container 2. Appropriate collection technique 3. Appropriate labeling i. Date ii. Time iii. Patient name 4. What results mean i. What is test sensitivity? a. Probability test will be positive in the presence of disease ii. Specificity a. Probability test will be negative in the absence of disease. iii. Limitations of the Test a. Positive predictive value b. Negative predictive value iv. Stability of the substance v. Where the test is being done vi. What disease is being tested? vii. Who is being tested? viii. Relying on labs a. One view? b. Snapshot c. Complements clinical assessment II. Blood tests A. Complete Blood Count 1. Metabolism Henry Geiter, Jr, RN, CCRN-CMC 2 Common Labs, Uncommon Knowledge

3 a. Hematocrit b. Hemoglobin c. Red blood cell count 2. Immunity a. White blood cells b. Platelets B. Blood Chemistry 1. Why do it? a. Electrolyte balance information b. Metabolic state 2. Components of CMP a. Glucose i. Hgb A 1c b. BUN i. Role in body ii. Where does it come from? c. Creatinine d. BUN/Creatinine ratio i. in renal failure ii. In dehydration e. Sodium i. In Dehydration ii. Seizures/cerebral edema iii. Diuretics iv. Calculating fluid volume deficit f. Potassium i. Hypokalemia ii. Hyperkalemia iii. DKA iv. False elevation g. CO 2 i. What is it really measuring? h. Albumin i. Calcium i. Binds to proteins ii. Corrected calcium levels iii. Role in muscle/heart/vasculature/neuro function iv. Ionized j. Bilirubin i. Conjugated ii. Unconjugated Henry Geiter, Jr, RN, CCRN-CMC 3 Common Labs, Uncommon Knowledge

4 iii. Liver disease iv. Bleeding q. Iron D. Drug levels 1. Role of albumin a. Total drug levels b. Free drug levels 2. Distribution 3. Role of cytochrome enzyme pathways E. Pancreatic tests 1. Amylase 2. Lipase F. Lactate 1. Arterial 2. Venous 3. Uses III. Body fluid tests A. Urinalysis 1. Color a. Can I make a rainbow? 2. Odor 3. Appearance 4. Specific Gravity 5. ph 6. RBCs 7. Protein 8. Glucose 9. Ketones 10. Nitrates 11. Bacteria 12. Leukocyte esterase 13. Bilirubin 14. Urobilinogen 15. Casts 16. Crystals B. Spot urine tests 1. Urine electrolytes 2. Urine creatinine 3. Urine protein 4. Other Henry Geiter, Jr, RN, CCRN-CMC 4 Common Labs, Uncommon Knowledge

5 C. Pleural fluid/ CSF 1. Cell count/differential 2. Glucose 3. LDH 4. Cytology 5. Protein 6. Other IV. Other Lab Tests V. Case Studies Selected References 1. Wedding, ME and Toenjes, SA: Medical Laboratory Procedures, FA Davis, Philadelphia, Rodak, B. F. (2007) Hematology: Clinical Principles & Applications (3 rd ed.). Philadelphia: W.B. Saunders Company. 3. Pagana, K. D., & Pagana, T. J. (2008) Manual of Diagnostic and Laboratory Tests (9 th ed.). St. Louis: Mosby. 4. Bakerman, S., Bakerman, P., & Strausbach, P. (2002). Bakerman's ABC's of Interpretive Laboratory Data. Scottsdale, AZ: Interpretive Laboratory Data. 5. D. McAule, P. (2011). Common Lab Values. Retrieved February 1, 2011, from Global RPH: 6. Goldman, L., & Ausiello, D. (2003). Cecil Textbook of Medicine. Boston: Little, Brown and Co. 7. Harmening, D. (2008). Clinical Hematologyand Fundementals of Hemostasis. Philadelphia: F.A. Davis. 8. Keith Conover, M. (2006, May 25). Blood Gases: Not as Compllicated as they Seem. Retrieved January 13, 2011, from Pittsburgh Mercy Hospital Departments of Emergency Medicine: 9. Pagana, K., & Pagana, T. (2009). Mosby's Manual of Diagnostic and Laboratory Tests. St. Louis: Mosby. 10. Richard McPherson, M., & Matthew Pincus, M. (2006). McPherson & Pincus: Henry's Clinical Diagnosis and Management by Laboratory Methods, 21st ed. Retrieved February 1, 2011, from mdconsult: u1.0-b cesec32&isbn= &type=bookpage&sectioneid=4-u1.0-b cesec68&uniqid= Speaker Contact Henry Geiter, Jr, RN, CCRN-CMC 5 Common Labs, Uncommon Knowledge

6 Henry Geiter, Jr, RN, CCRN-CMC 6 Common Labs, Uncommon Knowledge

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