513CHAPTER 26 Respiratory System

Continued

TABLE 26-10 DIAGNOSTIC STUDIESRespiratory System

STUDY DESCRIPTION AND PURPOSE NURSING RESPONSIBILITYBlood StudiesHemoglobin Test reflects amount of hemoglobin available for

combination with oxygen. Venous blood is used.Male: 13.2-17.3 g/dL (132-173 g/L).Female: 11.7-16.0 g/dL (117-160 g/L).

Explain procedure and its purpose.

Hematocrit Test reflects ratio of red blood cells to plasma. Increased hematocrit (polycythemia) found in chronic hypoxemia. Venous blood is used.Male: 39%-50% (0.39-0.50).Female: 35%-47% (0.35-0.47).

Explain procedure and its purpose.

ABGs Arterial blood is obtained through puncture of radial or femoral artery or through arterial catheter. Performed to assess acid-base balance, ventilation status, need for oxygen therapy, change in oxygen therapy, or change in ventilator settings.* Continuous ABG monitoring is also possible via a sensor or electrode inserted into arterial catheter.

Indicate whether patient is using O2 (percentage, L/min). Avoid change in oxygen therapy or interventions (e.g., suctioning, position change) for 20 min before obtaining sample. Assist with positioning (e.g., palm up, wrist slightly hyperextended if radial artery is used). Collect blood into heparinized syringe. To ensure accurate results, expel all air bubbles, and place sample in ice, unless it will be analyzed in less than 1 min. Apply pressure to artery for 5 min after specimen is obtained to prevent hematoma at the arterial puncture site.

Oximetry Test monitors arterial or venous oxygen saturation. Probe attaches to finger, toe, earlobe, bridge of the nose for SpO2 monitoring or is contained in a pulmonary artery catheter for SvO2 monitoring. Oximetry is used for intermittent or continuous monitoring and exercise testing.

Apply probe. When interpreting SpO2 and SvO2 values, first assess patient status and presence of factors that can alter accuracy of pulse oximeter reading. For SpO2 these include motion, low perfusion, cold extremities, bright lights, acrylic nails, dark skin color, carbon monoxide, and anemia. For SvO2, these include change in O2 delivery or O2 consumption.

Sputum StudiesCulture

and sensitivitySingle sputum specimen is collected in a sterile

container. Purpose is to diagnose bacterial infection, select antibiotic, and evaluate treatment. Takes 48-72 hr for results.

Instruct patient on how to produce a good specimen (see Gram stain). If patient cannot produce specimen, bronchoscopy may be used (see Fig. 26-12).

Gram stain Staining of sputum permits classification of bacteria into gram-negative and gram-positive types. Results guide therapy until culture and sensitivity results are obtained.

Instruct patient to expectorate sputum into container after coughing deeply. Obtain sputum (mucoidlike), not saliva. Obtain specimen in early morning after mouth care because secre-tions collect during night. If unsuccessful, try increasing oral fluid intake unless fluids are restricted. Collect sputum in sterile container (sputum trap) during suctioning or by aspirating secre-tions from the trachea. Send specimen to laboratory promptly.

Acid-fast smear and culture

Assesses sputum for acid-fast bacilli (e.g., Mycobac-terium tuberculosis). A series of three early-morning specimens is used.

Instruct patient how to produce a good specimen (see Gram stain). Cover specimen and send to laboratory for analysis.

Cytology Determines presence of abnormal cells that may indi-cate malignant condition. Single sputum specimen is collected in special container with fixative solution.

Send specimen to laboratory promptly. Instruct patient on how to produce a good specimen (see Gram stain). If patient cannot produce specimen, bronchoscopy may be used (see Fig. 26-12).

RadiologyChest x-ray Used to screen, diagnose, and evaluate changes

in respiratory system. Most common views are anterior-posterior (AP) and lateral.

Instruct patient to undress to waist, put on gown, and remove any metal between neck and waist.

Computed tomography (CT)

Performed for diagnosis of lesions difficult to assess (e.g., mediastinum, hilum, pleura) by conventional x-ray studies. Common types are helical or spiral CT (contrast media is usually used) and high-resolution CT scan (contrast media is not used). Spiral CT used to diagnose a pulmonary embolism.

Same as for chest x-ray. Contrast media may be given IV. Evalu-ation of BUN and serum creatinine is done before contrast to assess renal function. Assess if patient is allergic to shellfish (iodine) as the contrast is iodine based. Be sure the patient is well hydrated before and after procedure (to excrete contrast). Know that contrast injection may cause a feeling of being warm and flushed. Instruct the patient that he or she will need to lie very still on a hard table and the scanner will revolve around the body with clicking noises.

Magnetic resonance imaging (MRI)

Used for diagnosis of lesions difficult to assess by CT scan (e.g., lung apex) and for distinguishing vascular from nonvascular structures.

Same as for chest x-ray and CT scan, except contrast medium is not iodine based. If closed MRI used and patient has claus-trophobia, provide with relaxation or other modes to cope. Patient must remove all metal (e.g., jewelry, watch) before test. Patients with pacemakers and implantable cardioverter- defibrillators cannot undergo MRI.

ABGs, Arterial blood gases; BUN, blood urea nitrogen; IV, intravenous. *For reference intervals, see Table 26-1.

514 SECTION 5 Problems of Oxygenation: Ventilation

STUDY DESCRIPTION AND PURPOSE NURSING RESPONSIBILITYRadiologycontdVentilation-

perfusion (V/Q)Used to assess ventilation and perfusion of lungs. IV

radioisotope given to assess perfusion. For the venti-lation portion, the patient inhales a radioactive gas (xenon or krypton), which outlines the alveoli. Normal scans show homogeneous radioactivity. Diminished or absent radioactivity suggests lack of perfusion or airflow. Ventilation without perfusion suggests a pulmonary embolus.

Same as for chest x-ray. No precautions needed afterward because the gas and isotope transmit radioactivity for only a brief interval.

Pulmonary angiogram

Used to visualize pulmonary vasculature and locate obstruction or pathologic conditions (e.g., pulmonary embolus). Contrast medium is injected through a catheter threaded into pulmonary artery or right side of the heart. Series of x-rays are taken after contrast medium is injected into pulmonary artery. Chest CT is replacing angiography as it is less invasive.

Same as for chest x-ray. (See CT scan for contrast media precau-tions.) Check pressure dressing site after procedure. Monitor blood pressure, pulse, and circulation distal to injection site. Report and record significant changes.

Positron emission tomography (PET)

Used to distinguish benign and malignant pulmonary nodules. Because malignant lung cells have an increased uptake of glucose, the PET scan, which uses an IV radioactive glucose preparation, can demonstrate increased uptake of glucose in malignant lung cells.

Same as for chest x-ray study. No precautions are needed afterward because isotope only transmits radioactivity for brief interval. Encourage fluids afterward to excrete radioactive substance.

EndoscopyBronchoscopy Flexible fiberoptic scope is used for diagnosis, biopsy,

specimen collection, or assessment of changes. It may also be done to suction mucous plugs, lavage the lungs, or remove foreign objects.

Instruct patient to be on NPO status for 6-12 hr before the test. Obtain signed permit. Give sedative if ordered. After procedure, keep patient NPO until gag reflex returns and monitor for laryngeal edema; monitor for recovery from sedatives. Blood-tinged mucus is not abnormal. If biopsy was done, monitor for hemorrhage and pneumothorax.

Mediastinoscopy Scope is inserted through a small incision in the supra-sternal notch and advanced into the mediastinum to inspect and biopsy lymph nodes. Used to diagnose lung cancer, non-Hodgkins lymphoma, granulom-atous infections, and sarcoidosis.

Prepare patient for surgical intervention. Obtain signed permit. Performed in the operating room (OR) and the patient is given a general anesthetic. Afterward, monitor as for bronchoscopy.

BiopsyLung biopsy Specimens may be obtained by transbronchial or

percutaneous biopsy or via transthoracic needle aspiration (TTNA); video-assisted thorascopic surgery (VATS); or open lung biopsy. Transbronchial biopsy and VATS can be performed in the bronchoscopy suite. TTNA is done under CT guidance in radiology. Open lung is performed in the OR. VATS can also be done in the OR. These tests are used to obtain specimens for laboratory analysis.

Same as bronchoscopy if procedure done with bronchoscope, and same as thoracotomy if open lung biopsy done.

With a TTNA, check breath sounds q4hr for 24 hr and report any respiratory distress. Check incision site for bleeding. A chest x-ray should be done after TTNA or transbronchial biopsy to check for pneumothorax.

With VATS a chest tube may be in postprocedure until lung has reexpanded. Monitor breath sounds to follow chest reexpan-sion. Encourage deep breathing for lung reinflation. Obtain signed permit for all procedures.

Other TestsThoracentesis Used to obtain specimen of pleural fluid for diagnosis,

to remove pleural fluid, or to instill medication. Chest x-ray is always obtained after procedure to check for pneumothorax.

Explain procedure to patient and obtain signed permit before procedure, which is usually performed in the patients room. Position patient upright with elbows on an overbed table and feet supported. Instruct the patient not to talk or cough, and assist during procedure. Observe for signs of hypoxia and pneumothorax and verify breath sounds in all fields after procedure. Encourage deep breaths to expand lungs. Send labeled specimens to laboratory.

Pulmonary function tests

Used to evaluate lung function. Involves use of spirometer to assess air movement as patient performs prescribed respiratory maneuvers.

Avoid scheduling immediately after mealtime. Avoid adminis-tration of inhaled bronchodilator 6 hr before procedure. Explain procedure to patient. Assess for respiratory distress before procedure and report. Provide rest after the procedure.

TABLE 26-10 DIAGNOSTIC STUDIEScontdRespiratory System

NPO, Nothing by mouth.For reference intervals, see Tables 26-12 and 26-13.