Medical Diagnostics and Procedures Review

• Diagnostic testing objectives include recalling blood cells and their functions, identifying blood tests, and describing the nurse's role pre-, during, and post-testing.

Normal Structure and Function of Blood Cells

• Erythrocytes (RBCs) transport O2 and CO2.
• Thrombocytes (platelets) trigger clotting factors.
• Leukocytes (WBCs) have an inflammatory/immune response, found primarily in bone marrow.
  • Exceptions are T lymphocytes, which are produced in the thymus.
  • Lymphocytes (T and B), monocytes, eosinophils, neutrophils, and basophils are key leukocytes.
• Plasma is the fluid portion of blood that transports electrolytes to and from cells
  • Plasma contains nutrients, proteins, hormones, glucose, vitamins, amino acids, fatty acids, and waste products.
• Albumin maintains fluid balance by providing colloidal osmotic pressure and enhances bioavailability of drugs.
• Fibrinogen is important for blood coagulation and converts into fibrin threads with ionized calcium.
• Globulins (alpha, beta, gamma) function as antibodies or for enzymatic functions, and transport lipids, iron, and copper.
• Urea and creatinine are waste products that blood transports for renal excretion.

Laboratory Tests: Blood

• Blood samples can be venous, arterial, or capillary.
  • Venous samples are the primary source for sampling.
  • Arterial samples determine arterial blood gases (ABGs).
  • Capillary samples measure glucose, cholesterol, clotting times, hemoglobin, and hematocrit.
• A complete blood count (CBC) provides information on oxygen and carbon dioxide transport as well as information on immune/inflammatory responses.
• CBC components include red blood cell (RBC) count, hemoglobin level, hematocrit, RBC indices, white blood cell (WBC) count, and differential WBC count.
• Coagulation studies related to blood vessel injury include vascular spasm, plug formation, and blood clotting.
• Platelets measure the number, size, and shape of cells.
• A prothrombin time (PT) test can detect bleeding disorders caused by abnormalities of the extrinsic clotting system
  • PT is used to monitor effectiveness of warfarin therapy.
• International normalized ratio (INR) monitors the effect of anticoagulant therapy.
• Activated partial thromboplastin time (APTT) can detect bleeding disorders caused by abnormalities of the intrinsic clotting system
  • APTT is used to monitor effectiveness of heparin therapy.
• Fibrinogen can identify suspected bleeding disorders and monitor progressive liver disease.
• Blood chemistry tests include electrolytes, a basic metabolic panel (BMP), glucose, and hemoglobin A1c.
  • Electrolytes: Cations are positively charged, and anions are negatively charged.
  • BMP measures sodium, potassium, chloride, CO2, BUN, and serum creatinine.
  • Glucose is controlled by glucagon and insulin; serum glucose levels detect abnormal glucose metabolism.
  • Hemoglobin A1c (Hgb A1c) evaluates blood glucose levels over 2 to 3 months.
• Kidney function tests include blood urea nitrogen (BUN), serum creatinine, and glomerular filtration rate (GFR)
  • BUN is a by-product of protein metabolism.
  • Serum creatinine is a waste product of skeletal muscle metabolism.
  • GFR measures mLs filtered by the kidneys per minute.
• A lipid profile shows the total cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglycerides LDL cholesterol transports lipids from the liver to the body. HDL cholesterol transports excess cholesterol back to the liver. Triglycerides are fatty acids, protein, and glucose stored in adipose tissue and muscle.
• Liver tests (liver profile) include albumin, prealbumin, bilirubin, alanine aminotransferase (ALT), alkaline phosphatase (ALP), aspartate aminotransferase (AST) and Gamma-glutamyl transpeptidase (GGTP)
  • Albumin is a plasma protein that is synthesized by the liver, is responsible for colloidal oncotic pressure, and indicates nutritional status.
  • Prealbumin has much shorter half-life than albumin.
  • Bilirubin is synthesized in the liver, spleen, and bone marrow, is one of the components of bile, and also a by-product of hemolysis.
  • Alanine aminotransferase (ALT) found primarily in the liver is also a catalyst for amino acid production for liver disease.
  • Aspartate aminotransferase (AST) found primarily in the heart is an indicator for liver and bone disease.
  • Gamma-glutamyl transpeptidase (GGTP) found primarily in the liver and biliary tract assists the transportation of amino acids across cell membranes.
• Cardiac markers are proteins that leak out of injured heart muscle cells into the bloodstream.
  • Creatine kinase, found primarily in skeletal, cardiac, and brain tissue, usually indicates damage.
  • CK-BB (brain), CK-MB (heart), and CK-MM (skeletal muscle) are types of creatine kinase.
  • Myoglobin is an oxygen-transporting and storage protein released with muscle damage.
  • Troponin, can be detected 4 hours after an MI and is a complex in cardiac and skeletal muscle.
  • Homocysteine, folates, and vitamins B6 and B12 are necessary for the body to metabolize
• Brain natriuretic peptide (BNP) is a hormone produced by myocardial cells during times of increased pressure or overload.
  • Plasma concentrations of BNP reflect the severity of cardiac failure.
  • C-reactive protein (CRP) is used as inflammatory or autoimmune disorders.
• Arterial blood gas (ABG) examine arterial blood to assess a patient's oxygenation status and acid-base balance.

Laboratory Tests: Urine and Stool

• Urinalysis diagnoses urinary tract infections and detects diseases/disorders unrelated to the renal system.
• Stool tests identify disorders of the gastrointestinal (GI) tract, liver, and pancreas.
  • Stool tests analyze occult blood, fecal fat, urobilinogen, ova, and parasites.
  • Black, and tarry stools indicate an upper GI bleed.
  • Bright red blood in stool indicates lower GI bleed.
• Common sources for specimens from a culture include blood, throat, sputum, stool, urine, and wounds
• A culture comes back positive when there is sufficient bacteria.
• After the pathogen has been identified following a culture, its sensitivity to various antibiotics will be tested in order to determine which antibiotic therapy would be most efficient.

Diagnostic Examinations

• Radiography includes non-contrast and contrast studies.
  • Noncontrast studies include X-rays of the chest, bones, and abdomen as well as mammograms.
  • Contrast studies have the potential to cause allergic reactions and include intravenous pyelograms and upper & lower GI.
    • Intravenous pyelograms: GU, GI = KUB
    • Upper GI (barium swallow): esophagus, stomach, duodenum, and upper portion of the jejunum.
    • Lower GI (barium enema): ascending, transverse, descending colons, sigmoid colon, and rectum.
• Computed tomography uses a special scanner to visualize cross-sectional images.
  • CT scans may or may not use contrast medium and can be used on the abdomen, brain, chest, kidneys, and ureters.
• Magnetic resonance imaging (MRI) produces a cross-sectional image of the body without radiation exposure.
  • The MRI is the most common diagnostic examination for brain pathology and joint visualization but is costly.
• Positron emission tomography (PET) uses a nuclear study performed following an IV injection of radioactive chemicals to analyze color-coded images.
  • PET can be used for the brain, heart, and oncology.
• Electrocardiogram (ECG, EKG) uses waveform changes to indicate cardiac injury, disorders of the electrical conduction system, or cardiac enlargement.
• Endoscopy examines an organ/cavity using a fiberoptic video endoscope.
  • Separate ports allow instillation of drugs, suction, and the insertion of instruments for tissue/foreign object removal.
• Ultrasound provides visualization of soft-tissue organs.
• Needle aspirations and biopsies: Paracentesis removes ascites fluid from the peritoneal cavity
  • Thoracentesis removes fluid from the pleural space.
  • A Biopsy can surgically remove something through laparoscopic and endoscopic methods, by scraping, punch, or a scalpel.

Specimen Collection: Principles for Practice (Part II)

• Correct specimen collection, monitoring patient outcomes, and laboratory tests must be completed.
• Sharing results with the interdisciplinary team, using proficiency/judgment in obtaining specimens, and minimize patient discomfort.
• To ensure accuracy of the quality of diagnostic procedures wear hand hygiene, clean gloves or personal protective equipment, and label containers.
• Test value may vary by agency and its important to use normal, high, and low results. Consult the laboratory for questions.

Urine Specimen Collection

• Urinalysis provides information about kidney or metabolic function, nutrition, and systemic diseases.
• Types of urine tests and specimens include random urine specimen for routine urinalysis as well as culture and sensitivity (C&S).
• Timed urine specimen for quantitative analysis and analyzing chemical properties of urine are important.
• Assistive personnel can be delegated the skill of collecting urine specimens and should be informed to:
  • obtain the specimens at a specified time.
  • position patient as is necessary.
  • report to the nurse if the urine is not clear or if a patient is burning or unable to start stream.
• Unexpected outcomes and related interventions: If a urine specimen is contaminated with stool/toilet paper, the patient will be catheterized. Alternatively;
  • Repeat urine specimen collection instruction with patients.
• For a urine culture to be performed it must be positive for bacterial growth.
  • Findings must be reported to the healthcare provider including test findings.
  • Medications must be administered as ordered and patient monitored for fever and dysuria
• Lumen leading to balloon that holds catheter in place is punctured so make sure to notify provider for removal of existing for new insertion.

Collecting a Timed Specimen

• Some renal function and urine composition tests require that the urine collected stays over 2 to 72 hours
  • Elements such as amino acids, creatinine, hormones, glucose, and adrenocorticosteroids are often measured over this period
  • This process requires teamwork; and the skill for this can be tested by an assistive person (AP)
  • With timed collection and the correct methods to store it place urine collection is in progress and saving all urine.

Measuring Occult Blood in Stool:

• Hemoccult testing screens "not visible" blood in stool, while a DNA stool sample test identifies non-bleeding polyps with abnormal DNA.
  • Nursing staff should ask the skill of testing stool samples on patient in order to assist with blood removal
  • Report any if blood is detected to test and make to discard the original blood sample

Collecting Nose and Throat Specimens for Culture

• Nose or throat culture serve as a simple diagnostic tool.
  • These identify the presence of microorganisms.
  • Culture specimens should be obtained prior to any antibiotic regiment.
  • The task of collecting these culture specimens is to be delegated to assistive personnel to stop specimen contamination.
• To ensure that all unexpected outcomes follow test and that the bacteria grows after a notification procedure.
• Minor nasal bleeding in patients can cause applying pressure over the original bridge/ ice pack.

Blood Glucose Monitoring:

• Blood glucose monitoring (BMG) can be achieved with Glucose reflectance meters, and glucose monitoring with implantable sensors.
  • Blood and delegation of a patients condition by AP staff can lead to a glucose test based of what is used in the puncture procedure.
• In the event that a puncture site is bleeding or has a bruise, apply pressure over the site and notify the provider for further assistance.
  • If a patient’s glucose is above the target/ continues to monitor this issue by the nurse.

Diagnostic Procedures: Safety Guidelines

• Diagnostic procedures have safety guidelines that should be performed at patients' bedsides or in special equipped setting to ensure safety of all patients.
  • The nurse is responsible for this process: assessing a patient's knowledge/ procedure/ discharge teaching and also setting/ following instructions.
• It is important to ensure that the patient the post process they are using, which could be IV sedation along with the gastrological process.

Before a medical procedure:

• Ensure a patient’s documentation before sedatives are administered, and proper equipment is avaliable.

During a medical procedure:

• When using radioactive equipment and exposure is necessary, staff should be made aware of the safety measures to ensure harm is done to them.

After a medical procedure:

• Assess the patient’s ability to know and understand the sedatives that will be administered.
• Fall precautions are in place to limit harm.

Questions covering lab tests like CBC and urinalysis, plus procedures like colonoscopy, bronchoscopy, and bone marrow biopsy. Focus is on interpretation, pre/post-care, and nursing interventions. Review key concepts in medical diagnostics.