Blood Urea Nitrogen (BUN) Posted: 05 Sep 2010 10:11 PM PDT
Urea is the chief end product of protein metabolism. Formed in the liver from ammonia and excreted by the kidneys, urea constitutes 40% to 50% of the blood's nonprotein nitrogen. Because the level of reabsorption of urea in the renal tubules is directly related to the rate of urine flow through the kidneys, the blood urea nitrogen (BUN) level is less reliable indicator or uremia than is the serum creatinine level. The BUN test measures the nitrogen fraction. Purpose of Blood Urea Nitrogen Test - To confirm bacterecemia.
- To identify causative organism in bacterecemia and septicemia.
- To determine the cause of fever with an unknown origin.
Procedure for Blood Urea Nitrogen Test Patient Preparation - Tell the patient that the BUN test is used to evaluate kidney function.
- Inform the patient that he need not to restrict food and fluids, but should avoid diet high in meat.
- Tell the patient that the test requires a blood sample. Explain who will perform the venipuncture and when.
- Explain to the patient that he may experience slight discomfort from the tourniquet and needle puncture.
- Notify the laboratory and physician of medications the patient is taking that may affect test results; they may need to be restricted.
Implementation - Clean the venipuncture site first with an alcohol swab and then with a providone-iodine swab, starting at the site and working outward in a circular motion.
- Wait at least 1 minute for the skin to dry.
- Perform a venipuncture and draw 10 to 20 ml of blood for an adult, or 2 to 6 ml for a child.
- Clean the diaphragm tops of the culture bottles with alcohol or iodine and change the needle on the syringe.
- If using broth, add blood to each bottle until achieving a 1:5 or 1:10 dilution. For example, add 10 ml of blood to a 100-ml bottle. Note that the size of the bottle may vary depending on hospital protocol.
- If using a special resin, add blood to the resin in the bottles according to facility protocol, and invert gently to mix it.
- Draw the blood directly into special collection processing tube if using lysis-centrifugation technique (Isolator).
- Document the tentative diagnosis and current or recent antimicrobial therapy on the laboratory request.
- Send each sample to the laboratory immediately.
- Collect blood cultures before giving antimicrobial agents whenever possible because previous or current antimicrobial therapy may give false-negative results.
- To detect most causative agents, it's best to perform the blood cultures on 2 consecutive days.
Nursing Interventions - Use alcohol to remove the iodine from the venipuncture site.
- Monitor the venipuncture site for bleeding and signs of infection.
Interpretations Normal Results - BUN values normally range form 8 to 20 mg/dl (SI, 2.9 to 7.5 mmol/L)
- In elderly patients, BUN will show slightly higher values, possibly to 69 mg/dl (SI, 25.8 mmol/L).
Abnormal Results - Elevated BUN levels occurs in renal disease, reduced renal blood flow (due to dehydration), urinary tract obstruction, and increased protein catabolism (such as with burns).
- Low BUN levels occur in severe hepatic damage, malnutrition, and overhydration.
Interfering Factors - Hemolysis from rough handling of the sample.
- Use of chloramphenicol may possible decrease the BUN.
- Aminoglycosides, amphoterecin B, and methicillin may increase BUN by nephrotoxicity.
Complications - Hematoma at the puncture site.
Precaution - Handle the sample gently to prevent hemolysis.
Related posts: - Alpha-fetoprotein Blood Test
- Arterial Blood Gas Analysis
- Blood Chemistry Definitions
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Bone Marrow Aspiration and Biopsy Posted: 05 Sep 2010 10:04 PM PDT
Bone marrow, the soft tissue contained in the medullary canals of long bone and the interstices of cancellous bone, may be removed by aspiration or needle biopsy under local anesthesia. In aspiration biopsy, a fluid specimen in which pustulae of marrow is suspended is removed. In needle biopsy, a core of marrows – cells, not fluid – its removed. These methods are commonly used concurrently to obtain the best possible marrow specimens. Red marrow, which constitutes about 50% of an adult's marrow, actively produces stem cells that ultimately evolve into red blood cells, white blood cells and platelets. Yellow marrow contains fat cells and connective tissue and is inactive, but it can become active in response to the body's needs. Bleeding and infection may result from bone marrow biopsy at any site, but the most serious complications occur at the sternum. Such complications are rare but include puncture of the heart and major vessels, causing severe hemorrhage, and puncture of the mediastinum, causing mediastinitis of pneumomediastinum. Purpose of Bone Marrow Aspiration and Biopsy - To diagnose thrombocytopenia, leukemia, granulomas, anemias, and primary and metastatic tumors.
- To determine the causes of infection.
- To help stage disease such as with Hodgin's disease.
- To evaluate chemotherapy.
- To monitor myelosuppression.
Bone Marrow Aspiration and Biopsy Procedure Patient Preparation - Explain the procedure to the patient. A mild sedative will be given 1 hour before the test, if ordered.
- Tell the patient the test usually takes only 5 to 10 minutes and that more than one bone marrow specimen may be required.
- Let him know a blood sample will be collected before the biopsy for laboratory testing.
- Make sure the patient has signed a consent form.
- Check the patient for hypersensitivity to the local anesthetic.
- After confirming with the doctor, tell the patient which bone- sternum, anterior or posterior iliac crest, vertebral spinous process, ribs, or tibia – will be used as the biopsy site.
Implementation Aspiration Biopsy - The doctor prepares the biopsy site and injects a local anesthetic. He then inserts the needle through the skin, the subcutaneous tissue, and the cortex of the bone.
- The doctor removes the stylet from the needle and attaches a 10 to 20 ml syringe. He aspirates 0.2 to 0.5 ml of marrow and withdraws the needle.
- Pressure is applied to the site for 5 minutes while the marrow slides are being prepared. If the patient has thrombocytopenia, pressure is applied for 10 to 15 minutes.
- The biopsy site is cleaned again, and a sterile adhesive bandage is applied.
- If the doctor doesn't obtain an adequate marrow specimen on the first attempt, he may reposition the needle or remove and reinsert it in another site within the anesthetized area. If the second attempt fails, a needle biopsy may be necessary.
Needle Biopsy - After preparing the biopsy site and draping the area, the examiner marks the skin at the site with an indelible pencil or marking pen.
- A local anesthetic is then injected intradermally, subcutaneously, and at the bone's surface.
- The biopsy needle is inserted into the periosteum, and the needle guard is set as indicated. The needle is advanced with a steady boring motion until the outer needle passes through the bone's cortex.
- The inner needle with trephine tip is inserted into the outer needle. By alternately rotating the inner needle clockwise and counterclockwise, the examiner directs the needle into the marrow cavity and then removes a tissue plug.
- The needle assembly is withdrawn, and the marrow is expelled into a labeled bottle containing Zenker's acetic acid solution.
- After the biopsy site is cleaned, a sterile adhesive bandage or a pressure dressing is applied.
Nursing Interventions - While the marrow slides are being prepared, apply pressure to the biopsy site until bleeding stops.
- Clean the biopsy site and apply a sterile dressing.
- Monitor the patient's vital signs and the biopsy site for signs and symptoms of infection.
Interpretation Normal Results - Yellow marrow contains fat cells and connective tissue.
- Red marrow contains hematopoietic cells, fat cells, and connective tissue.
- The iron satin, which measures hemosiderin (storage iron), has a +2 level.
- The sudan black B satin, which shows granulocytes is negative.
- The periodic acid-Schiff (PAS) stain, which detects glycogen reactions, is negative.
Abnormal Results - Decreased hemosiderin levels in an iron stain may indicate a true iron deficiency.
- Increased hemosiderin levels may suggest other types of anemias or blood disorders.
- A positive stain can differentiate acute myelogenous leukemia from acute lymphoblastic leukemia (negative stain).
- A positive stain may also suggest granulation in myeloblasts.
- A positive PAS stain may suggest acute or chronic lymphocyte leukemia, amyloidosis, thalasemia, lymphoma, infectious mononucleosis, iron-deficiency anemia, or sideroblastic anemia.
Complications - Hemorrhage and infection
- Puncture of the mediastinum (sternum)
Precautions - Know that bone marrow biopsy is contraindicated in the patient with a severe bleeding disorder.
- Send the tissue specimen or slide to the laboratory immediately.
Interfering Factors - Failure to obtain a representative specimen.
- Failure to use a fixative for histologic analysis.
Related posts: - Magnetic Resonance Imaging of Bone and Soft Tissue (MRI)
- Pathophysiology of Leukemia
- Nursing Care Plan – Leukemia
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Barium Swallow (Esophagography) Posted: 05 Sep 2010 09:51 PM PDT
Barium swallow, also known as esophagography, is the radiographic or fluoroscopic examination of the pharynx and the fluoroscopic examination of the esophagus after ingestion of thick and thin mixtures of barium sulfate. This test, is commonly performed as part of the upper GI series, is indicated for patients with history of dysphagia and regurgitation. Further testing is usually required for a definitive diagnosis. After the barium is swallowed, it pours over the base of the tongue into the pharynx. A peristaltic wave propels it through the entire length of the esophagus in about 2 seconds. When the peristaltic wave reaches the base of the esophagus, the cardiac sphincter opens, allowing the barium to enter the stomach. After passage of the barium, the cardiac sphincter closes. Normally, it evenly fills and distends the lumen of the pharynx and esophagus, and the mucosa appears smooth and regular. Purpose of Barium Swallow - To diagnose hiatal hernia, diverticula, and varices.
- To detect strictures, ulcers, tumors, polyps, and motility disorders.
Procedure for Barium Swallow Patient Preparation - Explain to the patient that this test evaluates the function of the pharynx and esophagus.
- Instruct the patient to fast after midnight before the test.
- If the patient is infant, delay the feeding to ensure complete digestion of the barium.
- Explain that the test takes approximately 30 minutes.
- Describe the milkshake consistency and chalky taste of the barium preparation the patient will ingest; although it's flavored, it may be unpleasant to swallow.
- Tell him he'll first receive a thick mixture and then a thin one and that he must drink 12 to 14 oz (355 to 414 ml) during the examination.
- Inform him that he'll be placed in various positions on a tilting radiograph table and that radiographs will be taken.
- If gastric reflux is suspected, withhold antacids, histamine-2 (H2) blockers, and proton pump inhibitors, as ordered.
- Just before the procedure, instruct the patient to put a hospital gown without snap closures and to remove jewelry, dentures, hairpins, and other radiopaque objects from the radiograph field.
- Check the patient history for contraindications to the barium swallow, such as intestinal obstruction and pregnancy. Radiation may have teratogenic effects.
Implementation - The patient is placed in an upright position behind the fluoroscopic screen, and his heart, lungs, and abdomen are examined.
- The patient is instructed to take one swallow of the thick barium mixture; pharyngeal action is recorded using cineradiography.
- The patient is instructed to take several swallows of the thin barium mixture. Passage of the barium is examined fluoroscopically; spot films of the esophageal region are taken from lateral angles and from the right and left posteroanterior angles.
- To accentuate small strictures or demonstrate dysphagia, the patient may be asked to swallow a "barium marshmallow" (soft white bread soaked in barium) or a barium pill.
- The patient is then secured to the X-ray table and rotated to trendelenburg position to evaluate esophageal peristalsis or demonstrate hiatal hernia and gastric reflux.
- The patient is instructed to take several swallows of barium while the esophagus is examined fluoroscopically; spot films are taken.
- After the table is rotated to a horizontal position, the patient takes several swallows of the barium so that the esophageal junction and peristalsis may be evaluated.
- Passage of the barium is fluoroscopically observed and the spot films are taken with the patient in the supine and prone position.
- During fluoroscopic examination of the esophagus, the stomach and the duodenum are also carefully studied because neoplasms in these areas may invade the esophagus and cause obstruction.
Nursing Interventions for Barium Swallow - Check the additional films and fluoroscopic evaluations haven't been ordered before allowing the patient to resume his usual diet.
- Instruct the patient to drink plenty of fluids, unless contraindicated, to help eliminate the barium.
- Give cathartic as prescribed.
- Tell the patient to notify the physician if he fails to expel the barium in 2 to 3 days.
- Inform the patient that stools will be chalky and light colored for 24 to 72 hours.
Interpretation Normal Results - The swallowed barium bolus pours over the base of the tongue into the pharynx.
- A peristaltic wave reaches the base of the esophagus, the cardiac sphincter opens, allowing the bolus to enter the stomach. After the passage of the bolus, the cardiac sphincter closes.
- The bolus evenly fills and distends the lumen of the pharynx and esophagus, and the mucosa appears smooth and regular.
Abnormal Results - Barium swallow may reveal hiatal hernia, diverticula, and varices.
- Strictures, tumors, polyps, ulcers, and motility disorders, such as pharyngeal muscular disorders, esophageal spasms, and achalasia (cardiospasm) may be detected.
Complications - Barium retained in the intestine may harden, causing obstruction or fecal impaction.
- Abdominal distention and absent bowel sounds, which may indicate constipation and may suggest barium impaction.
Related posts: - Arthrography
- What is a Barium Enema?
- What is Hiatal Hernia
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