Oxygenation

Care of the Patient's Respiratory Needs  1. Anatomy of the respiratory system a. upper respiratory tract i. composed of five parts a. nose, sinuses, pharynx, larynx, trachea b. lower respiratory tract i. left lung a. composed of two lobes 1. superior, inferior 2. left lung is narrower than the right to accommodate the heart b. one left mainstem bronchi c. two secondary (lobar) bronchi 1. one into each lobe of the left lung d. numerous tertiary (segmental) bronchi e. numerous subsegmental bronchi f. numerous bronchioles g. numerous terminal bronchioles h. numerous alveolar ducts i. numerous alveoli 1. the basic unit of gas exchange ii. right lung a. composed of three lobes 1. superior, middle, inferior b. one right mainstem bronchi 1. shorter, straighter, wider than the left 2. most aspirated foreign objects lodge in this mainstem bronchi c. three secondary (lobar) bronchi 1. one into each lobe of the right lung d. numerous tertiary (segmental) bronchi e. numerous subsegmental bronchi f. numerous bronchioles g. numerous terminal bronchioles h. numerous alveolar ducts i. numerous alveoli 1. the basic unit of gas exchange 2. Normal function of the respiratory system a. distribution of air in the lungs (ventilation) i. the physical process of moving air into and out of the lungs ii. influenced by volume and intrapulmonary (inside the lung) and intrapleural (inside the pleura) pressure changes in the thoracic cavity a. at rest 1. intrapulmonary pressure normally is 760 mm Hg 2. intrapleural pressure normally is 756 mm Hg 3. atmospheric pressure normally is 760 mm Hg b. during inspiration 1. the diaphragm contracts and flattens out to increase the diameter of the thoracic cavity 2. the external intercostal muscles contract, elevating the rib cage and moving the sternum forward to expand the lateral and anteroposterior diameter of the thoracic cavity intrapulmonary pressure drops to 758 mm Hg (2 mm Hg below atmospheric pressure) intrapleural pressure drops to 754 mm Hg the above sets up a pressure gradient as a result, atmospheric air rushes into the lungs from an area of high pressure (the atmosphere) to an area of low pressure (the lungs) during expiration 1. the diaphragm relaxes and rises to its resting state 2. the external intercostal muscles relax, the rib cage descends, and the sternum moves back to its resting state 3. intrapulmonary pressure elevates to 763 mm Hg 4. intrapleural pressure returns to 756 mm Hg 5. the above sets up a pressure gradient 6. as a result, pulmonary air rushes out into the atmosphere from an area of high pressure (the lungs) to an area of low pressure (the atmosphere)

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b. gas diffusion i. influenced by the partial pressures of oxygen (PaO 2) and carbon dioxide (PaCO 2) a. partial pressure is the pressure exerted by each of these gases in a mixture according to its concentration in the mixture b. typical partial pressures of oxygen and carbon dioxide in the alveoli 1. PaO 2 = 100 mm Hg 2. PaCO 2 = 40 mm Hg c. typical partial pressures of oxygen and carbon dioxide in the venous capillaries 1. PaO 2 = 60 mm Hg 2. PaCO 2 = 46 mm Hg diffusion of oxygen and carbon dioxide between the alveoli and venous capillaries goes from an area of higher concentration or pressure to an area of lower ii. concentration or pressure, e.g.:

a. oxygen diffuses from the alveoli into the venous capillaries during inhalation because the PaO 2 is higher in the alveoli (100 mm Hg) and lower in the venous capillaries (40 mm Hg)

b. carbon dioxide diffuses from the venous capillaries into the alveoli during exhalation because the PaCO 2 is higher in the venous capillaries (46 mm Hg) and lower in the alveoli (40 mm Hg)

c. gas transport i. transportation of O 2 a. 97% of oxygen combines loosely with the hemoglobin in the red blood cells and is transported in the plasma as oxyhemoglobin b. 3% of the oxygen is dissolved and transported in the fluid of the plasma and cells ii. transportation of CO 2 a. 65% of carbon dioxide is transported in the form of bicarbonate (HCO 3-) inside the RBCs b. 30% of carbon dioxide is transported by reduced hemoglobin, which combines with carbon dioxide to form carbaminohemoglobin c. 5% of carbon dioxide is transported in solution in the plasma as carbonic acid, which is a compound formed when carbon dioxide combines with water

d. regulation of breathing i. chemosensitive area in the pons and medulla oblongata a. highly sensitive to increases in PaCO 2 and hydrogen ion concentration 1. increased PaCO 2 and hydrogen ion concentration (acid pH) leads to increased rate and depth of respiration 2. decreased PaCO 2 and hydrogen ion concentration (alkaline pH) leads to decreased rate and depth of respiration ii. chemoreceptors in the carotid and aortic bodies a. highly sensitive to decreased PaO 2 1. decreased PaO 2 leads to increased rate and depth of respiration 2. increased PaO 2 leads to decreased rate and depth of respiration b. also known as the "hypoxic" drive to breath 1. chronic lung conditions, such as emphysema, cause clients to live with continuously increased PaCO 2 levels so they are dependent on this drive, not in decreased PaCO 2 levels, to breath

2. consequently, clients with chronic lung conditions should receive only low concentrations of supplemental O 2! e. defenses of the respiratory tract i. hairs at the entrance of the nose and in the nasal turbinates, which filter large and small particles and/or organisms ii. respiratory mucus membranes, which entrap large and small particles and/or organisms iii. cilia (hairlike projections of the respiratory mucus membranes), which beat entrapped large or small particles and/or organisms toward the pharynx to be

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expectorated a. upper respiratory tract (nasal) cilia beat downward b. lower respiratory tract cilia beat upward iv. the cough reflex, which rids the lower respiratory tract of large or small particles and/or organisms v. the sneeze reflex, which rids the upper respiratory tract of large or small particles and/or organisms Factors influencing respiration a. body position i. upright position allows greatest ease of lung expansion a. abdominal contents are pulled down away from the diaphragm by gravity ii. lying position causes the greatest difficulty of expansion a. abdominal contents are pushed against the diaphragm by gravity b. activity and exercise i. strenuous exercise increases oxygen demand by the body and carbon dioxide production which results in increased rate and depth of respiration ii. routine activity and exercise has a training effect (or efficiency in oxygen utilization) and, consequently, decreases oxygen demand, carbon dioxide production, and rate and depth of respiration during activity and exercise c. age i. changes in the respiratory system as a result of aging: a. decreased elastin and increased collagen, which decreases lung recoil and compliance b. enlargement of the alveoli, which increases dead space and residual volume c. hypertrophy of the bronchial mucus glands d. decreased respiratory muscle strength, which decreases effectiveness of cough and respiration e. decreased number and motility of the cilia d. pregnancy i. during the last trimester of pregnancy, the pregnant uterus is large enough to displace the diaphragm upward ii. extra work of carrying excess weight due to pregnant uterus increases oxygen demand and carbon dioxide production which results in increased rate and depth of respiration e. body weight i. protuberant abdomen displaces the diaphragm upward ii. extra work of carrying excess weight increases oxygen demand and carbon dioxide production which results in increased rate and depth of respiration f. environment i. partial pressure of oxygen in the atmosphere a. decreased partial pressure of oxygen in higher altitudes (e.g., the partial pressure of oxygen in the atmosphere at 10,000 feet above sea level is 60 mm Hg compared to 100 mm Hg at sea level) increases oxygen demand and carbon dioxide production which results in increased rate and depth of respiration ii. heat a. increased environmental temperature is accompanied by vasodilatation that increases oxygen demand and carbon dioxide production which results in increased rate and depth of respiration iii. pollutants g. life-style i. cigarette smoking ii. occupation a. stone blasters: predisposed to silicosis b. asbestos workers: predisposed to asbestosis c. coal miners: predisposed to anthracosis d. farmers: predisposed to organic dust disease

d. farmers: predisposed to organic dust disease iii. sedentary life-style a. lack of routine activity or exercise that prevents a training effect (or efficiency in oxygen utilization) and, consequently, increases oxygen demand, carbon dioxide production, and rate and depth of respiration during activity and exercise

4. Common alterations in respiratory function: hypoxia a. inadequate cellular oxygen b. etiology of hypoxia i. any condition that decreases ventilation, e.g.: a. weakened respiratory muscles 1. e.g., aging, neuromuscular diseases (e.g., multiple sclerosis, muscular dystrophy), neurological injury (e.g., spinal -cord injury) b. shallow breathing 1. e.g., bedrest, pain, administration of opioid analgesics or anesthesia c. decreased lung compliance (the ability of the lungs to expand during inspiration) 1. e.g., inflexibility of the rib cage, deformed rib cage (kyphosis), inelasticity of the lungs (emphysema) d. decreased lung recoil (the tendency of the lungs to contract during expiration) 1. e.g., inflexibility of the rib cage, deformed rib cage (kyphosis), inelasticity of the lungs (emphysema) e. decreased production of surfactant in the alveoli 1. a lipoprotein that decreases alveolar surface tension which prevents the alveoli from totally recoiling between each breath and, consequently, the pressure needed to inflate the alveoli on subsequent breaths

2. production of surfactant is normally stimulated by yawning, sighing, or taking deep breaths 3. e.g., atelectasis, prematurity ii. any condition that decreases diffusion of gases, e.g.: a. alveolarhypoventilation 1. e.g., pulmonary edema (alveoli filled with fluid), pneumonia (alveoli filled with inflammatory exudate), atelectasis (alveoli collapsed) iii. any condition that decreases transportation of gases, e.g.: a. decreased cardiac output (CO) 1. e.g., heart muscle damage, shock, pooling of blood in the extremities b. decreased number of erythrocytes 1. e.g., anemia iv. any condition that decreases the partial pressure of oxygen in the atmosphere, e.g.: a. e.g., high altitudes v. any condition that increases the demand for oxygen a. e.g., activity and exercise, fever (basal metabolic rate increases 7% for each degree increase in temperature) vi. any condition that shunts blood from the right side to the left side of the heart (mixes oxygenated with unoxygenated blood) a. e.g., patent ductus arteriosus (opening between pulmonary artery and the aorta), ventral-septal defects, atrial-septal defects vii. any condition that alters the binding of hemoglobin with oxygen a. e.g., carbon monoxide poisoning, cyanide poisoning c. signs/symptoms of hypoxia i. increased, rapid pulse ii. rapid, shallow respirations and dyspnea iii. increased restlessness or lightheadedness iv. flaring of the nares v. substernal and/or intercostal retractions vi. cyanosis a. bluish discoloration of the skin, nail beds, and mucus membranes 5. Common alteration in respiratory function: hypoxemia a. reduced oxygen tension in arterial blood b. signs/symptoms i. PaO 2 less than 80 mm Hg ii. does not necessarily mean cells are receiving less oxygen iii. signs/symptoms of hypoxia occur when the PaO 2 drops below 50 mm Hg (oxygen-hemoglobin dissociation curve) a. at a PaO 2 of less than 50 mm Hg, the affinity of oxygen and hemoglobin decreases, less oxygen binds with hemoglobin, more oxygen is unloaded from hemoglobin to the cells, and oxygen saturation drops; therefore: 1. if PaO 2 is more than 50 mm Hg, signs/symptoms of hypoxia are usually not present

2. if PaO 2 is less than 50 mm Hg, signs and symptoms of hypoxia are usually present 6.

Common alteration in respiratory function: hypercapnia a. increased carbon dioxide tension in arterial blood b. signs/symptoms i. PaCO 2 greater than 45 mm Hg

7. Common alteration in respiratory function: hypocapnia a. decreased carbon dioxide tension in arterial blood b. signs/symptoms i. PaCO 2 less than 35 mm Hg 8. Common interventions for alterations in the respiratory system a. promoting healthy respirations i. positioning the client to allow for maximum chest expansion, e.g.: a. semi-fowler’s position 1. sitting in bed at 45° of flexion b. high-fowlers position 1. sitting in bed at 90° of flexion c. orthopneic position 1. sitting in bed and leaning over an overbed table ii. encouraging or providing frequent changes in position iii. encouraging ambulation iv. implementing measures that promote comfort, such as giving pain medications b. deep-breathing and coughing

i. abdominal (diaphragmatic) breathing ii. pursed-lip breathing a. creates resistance to air flowing out of the lungs and prolongs exhalation iii. apical or basal expansion exercises a. apical expansion exercises 1. the nurse a. places his/her hands below the clavicles exerting moderate pressure 2. the client: a. concentrates on expanding the upper chest forward and upward while inhaling b. holds his/her breath for 3 - 4 seconds c. exhales passively and slowly through the mouth or nose b. basal expansion exercises 1. the nurse a. places his/her hands on the lower ribs along the midaxillary lines exerting moderate pressure 2. the client a. concentrates on expanding the lower chest outward while inhaling b. holds his/her breath for 3 - 4 seconds c. exhales passively and slowly through the mouth or nose c. hydration i. encourage a fluid intake of 2,000 - 3,000 milliliters a day a. promotes moist respiratory mucus membranes and thin respiratory tract secretions that can be readily moved by ciliary action and expectorated ii. add water vapor to inspired air with room humidifiers if the environment has a low humidity a. promotes moist respiratory mucus membranes and thin respiratory tract secretions that can be readily moved by ciliary action and expectorated d. medications i. nonselective adrenergic receptors a. stimulate b 2 receptors in bronchial smooth muscle, thereby promoting bronchodilation through relaxation of bronchial smooth muscle 1. also have a STRONG b 1 receptor response 2. also have a STRONG a 1 and a 2 receptor response 3. examples: a. epinephrine b. ephedrine ii. nonselective b -adrenergic receptors a. stimulate b 2 receptors in bronchial smooth muscle, thereby promoting bronchodilation through relaxation of bronchial smooth muscle b. also have a STRONG b 1 receptor response 1. examples: a. isoproterenol (Isuprel) iii. selective b 2 - adrenergic receptors a. stimulate b 2 receptors in bronchial smooth muscle, thereby promoting bronchodilation through relaxation of bronchial smooth muscle b. also have a WEAK b 1 receptor response 1. examples: a. isoetharine inhalation solution (Bronkosol) b. albuterol aerosol (proventil) c. metaproterenol (Alupent) d. terbutaline (Brethine) iv. methylxanthines a. inhibit phosphodiesterase, which breaks down cyclic adenosine monophosphate (AMP) that constricts bronchial smooth muscle, thereby promoting

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bronchodilation through relaxation of bronchial smooth muscle 1. examples: a. theophylline (Elixophyllin, Theo-Dur, Slo-bid, Theolair, Aerolate) adrenal glucocorticoids a. decrease vascular permeability, inhibit leukocyte aggregation and arachidonic acid metabolism, and limit the release of lysosomal enzymes, thereby reducing inflammation and the inflammatory response in respiratory passages b. examples: 1. Prednisone 2. Beclomethasone (Vanceril) centrally acting antitussives a. depress the cough center in the medulla of the brainstem, thereby reducing cough production b. examples: 1. narcotic a. codeine 2. nonnarcotic a. dextromethorphan (Robitussin) b. diphenydramine (Benylin) c. benzonatate (Tessalon Perles) peripherally acting antitussives a. anesthesize the stretch receptors in the respiratory passages, lungs, and pleura, thereby reducing cough production b. examples: 1. benzonatate (Tessalon Perles) mucolytics a. split disulfide links of mucoproteins, thereby reducing the viscosity of respiratory mucus secretions and facilitating their removal by coughing, postural drainage, and mechanical means b. examples: 1. water 2. acetylcysteine (Mucomyst, Mucosil) expectorants a. stimulate the flow and reduce the viscosity and surface tension of respiratory mucus secretions, thereby rendering the cough more productive b. examples:

1. guaifenesin (Anti-Tuss) 2. Terpin Hydrate 3. potassium iodide x. decongestants a. stimulate a adrenergic receptors, thereby causing vasoconstriction and shrinkage of swollen mucus membranes in nasal passages b. examples: 1. ephedrine sulfate (Efedron) 2. pseudoephedrine hydrochloride (Sudafed) xi. antihistamines a. bind competitively with histamine at H1-receptor sites to antagonize the effects of histamine at the receptor sites, thereby reducing rhinnorhea and respiratory mucus secretions

b. examples: 1. diphenhydramine hydrochloride (Benadryl) 2. terfenadine (Seldane) e. lung inflation devices i. used to promote the following: a. improved pulmonary ventilation b. counteract the effects of anesthesia and/or hypoventilation c. loosen mucus secretions from the respiratory tract d. facilitate respiratory gaseous exchange e. expand collapsed alveoli ii. example: a. incentive spirometer (sustained maximal inspiration device [SMI]) b. the nurse teaches the client to: 1. hold or place the spirometer in an upright position 2. exhale normally 3. seal lips around mouthpiece 4. take slow, deep breath to elevate the balls or cylinder and then hold for 2 seconds, increasing to 6 seconds 5. remove mouthpiece and exhale normally 6. cough f. percussion i. forceful striking of the skin with cupped hands to mechanically dislodge viscous mucus secretions from congested lung segments in the respiratory tract g. vibration i. vigorous quiverings against the chest wall produced by the hands to increase the turbulence of exhaled air and loosen viscous mucus secretions from congested lung segments in the repiratory tract

h. postural drainage (PD) i. placement of a client in a wide variety of positions to drain particular lung segments of secretions by gravity ii. the nurse needs to: a. schedule (PD) for shortly before, not after, meals to prevent nausea and vomiting b. monitor client’s tolerance of postural drainage position by checking his/her vital signs and for pallor, diaphoresis, and fatigue i. suctioning i. aspiration of secretions from the upper or lower respiratory tract through a rubber or polyethylene catheter connected to a suction machine or wall outlet ii. types of suctioning a. oropharyngeal 1. insertion of a catheter through the mouth into the pharynx to aspirate secretions from the upper respiratory tract b. nasopharyngeal 1. insertion a catheter through the either of the nares to the pharynx to aspirate secretions from the upper respiratory tract c. endotracheal 1. insertion of a catheter through either of the nares or an endotracheal or tracheostomy tube to the trachea and bronchi to aspirate secretions from the lower respiratory tract

j. oxygen therapy i. common low-flow delivery systems for oxygen therapy a. deliver oxygen at flow rates that supplement the oxygen contained in ambient (room) air b. examples: 1. nasal cannula a. a rubber or plastic tube that extends around the client’s face with curved prongs that fit into the nares b. FiO 2 delivered i. 24% @ 1L/min ii. 28% @ 2L/min iii. 32% @ 3L/min iv. 36% @ 4L/min v. 40% @ 5L/min vi. 44% @ 6L/min 2. simple face mask a. a mask that covers the client’s face and nose b. FiO 2 delivered i. 40% @ 5L/min ii. 45% - 50% @ 6L/min iii. 55% - 60% @ 8L/min 3. partial rebreather mask a. a mask with an oxygen reservoir bag attached to it in which: i. the first part of the client’s exhaled air is mixed with 100 oxygen in the oxygen reservoir bag ii. the remaining part of the client’s exhaled air exits through vents iii. during the next inhalation, the client rebreathes about one-third of his/her previously expired air from the oxygen reservoir bag iv. FiO2 delivered a. 70% - 90% @ 6- 15 L/min, a liter flow rate high enough to maintain the oxygen reservoir bag two-thirds full during inspiration

4. nonrebreather mask a. a mask with an oxygen reservoir bag attached to it in which: i. no part of the client’s exhaled air is mixed with 100% oxygen in the oxygen reservoir bag because of a one-way valve ii. all the client’s exhaled air exits through vents on the face mask because of one-way valves iii. during the next inhalation, the client breathes all of his/her air from the oxygen reservoir bag because of the one -way valves over the vents of the face mask

b. Fi0 2 delivered i. 60% - 100% @ 6 - 15 L/min, a liter flow rate high enough to maintain the oxygen reservoir bag two-thirds full during inspiration ii. common high-flow oxygen delivery systems for oxygen therapy a. deliver oxygen at flow rates that meet or exceed the client’s inspiratory flow rate allowing an accurate delivery of inspired oxygen b. examples: 1. venturi mask a. a mask with wide bore tubing attached to it with various color -coded jet adapters that allows delivery of precise amounts of oxygen to the client

b. Fi0 2 delivered i. green jet adapter a. 24% @ 3 L/min b. 26% @ 3 L/min c. 28% @ 6 L/min d. 30% @ 6 L/min ii. white jet adapter a. 35% @ 9 L/min b. 40% @ 12 L/min c. 50% @ 15 L/min 2. face tent a. a tent that partially covers the client’s nose and mouth b. FiO 2 delivered i. 24 - 100%, with flow rates of at least 10 L/min k. artificial airways i. oropharyngeal tube a. a s-shaped, plastic tube that is inserted through the mouth and terminates in the posterior pharynx ii. nasopharnygeal tube a. a plastic tube that is inserted through a nostril and terminates in the pharynx below the upper edge of the glottis iii. endotracheal tube a. a curved, polyvinylchloride tube that is inserted through either the mouth or nose into the trachea just superior to the bifurcation of the trachea with the guide of a laryngoscope

iv. tracheostomy tube a. a curved, polyvinylchloride tube that is inserted through a tracheotomy (surgical incision into the trachea just below the first or second tracheal cartilage) just superior to the bifurcation of the trachea

l. chest tubes and drainage systems i. a tube inserted through the skin and intercostal space into the pleural cavity and connected to a one, two, or three bottle closed system to remove a collection of air or fluid from the pleural cavity and help reexpand the lung

9. Diagnostic studies a. blood tests i. red blood cell count a. collection of a specimen of blood to measure the total amount of red blood cells in a cubic milliliter of blood ii. hemoglobin a. collection of a specimen of blood to measure the amount of hemoglobin in the blood iii. hematocrit a. collection of a specimen of blood to measure the volume of red blood cells found in 100 milliliters of blood expressed as a percentage iv. arterial blood gases a. insertion of a needle into an artery (usually the radial or ulnar) to collect an arterial blood sample to ascertain the following: 1. PaO 2 (normal 80 - 100 mm Hg) 2. PaCO 2 (normal 35 - 45 mm Hg) 3. pH (normal 7.35 to 7.45) 4. HCO3- (normal 21 - 28 mEg/L) b. sputum tests i. collection of mucous from the lower respiratory tract to ascertain the following: a. the presence of gram-positive or gram-negative bacteria (gram stain) b. number and types of pathogens in the sputum (sputum for culture and sensitivity) c. presence of tuberculosis (sputum for acid-fast bacillus) d. typical and/or atypical cells (sputum for cytology) c. indirect visualization studies i. chest x-ray a. plain radiograph of the chest to determine gross anatomic features and/or abnormalities of the lower respiratory tract b. can be performed in the following positions: 1. anteroposterior (AP): front to back 2. posteroanterior (PA): back to front 3. right lateral (RL) 4. left lateral (LL) ii. computed tomography a. use of computerized tomograms (serial radiographs) to provide three-dimensional information about the gross anatomic features and/or abnormalities of the upper and/or lower respiratory tract

iii. bronchogram a. instillation of a radiopaque contrast medium into the trachea followed by plain radiographs to determine gross anatomic features and/or abnormalities of the lower respiratory tract

iv. pulmonary arteriography a. injection of a radiopaque contrast medium into an artery (usually pulmonary) to assess the arterial blood supply to the lower respiratory tract v. renography (lung scan) a. injection of a radionuclide medium into a vein and monitoring its uptake and then inhalation of a radioactive gas and monitoring its uptake to provide gross information about alveolar perfusion and ventilation and lower respiratory tract structure and function

d. direct visualization studies i. bronchoscopy a. insertion of a bronchoscope into the lower respiratory tract to directly visualize the lower respiratory tract ii. laryngoscopy a. insertion of a laryngoscope into the upper respiratory tract to directly visualize the larynx e. pulmonary function tests i. inhalation or exhalation through a mouthpiece connected to a spirometer to ascertain the following lung volumes and/or calculate the following pulmonary

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capacities: a. tidal volume (TV) 1. amount of air inhaled or exhaled with each breath under resting conditions b. inspiratory reserve volume (IRV) 1. amount of air that can be forcefully inhaled after a normal tidal volume inhalation c. expiratory reserve volume (ERV) 1. amount of air that can be forcefully exhaled after a normal tidal volume exhalation d. residual volume (RV) 1. amount of air remaining in the lungs after a forced exhalation e. total lung capacity (TLC) 1. maximum amount of air contained in the lungs after a maximum inspiratory effort 2. TLC = TV + IRV + ERV + RV f. vital capacity (VC) 1. maximum amount of air that can be expired after a maximum respiratory effort 2. VC = TV + IRV + ERV (should be 80% of the TLC) g. inspiratory capacity (IC) 1. maximum amount of air that can inspired after a normal expiration 2. IC = TV + IRV h. functional residual capacity (FRC) 1. volume of air remaining in the lungs after a normal tidal volume of expiration 2. FRC = ERV + RV thoracentesis i. insertion of a needle through the skin surface to aspirate pleural fluid or air from the pleural cavity percutaneous lung biopsy i. insertion of a trocar through the skin surface into the lung and then passing a biopsy needle through the trocar to obtain a tissue specimen to assess abnormalities of lung cell structure skin tests i. intradermal injection of a purified protein derivative of an infectious microorganism (antigen) to determine exposure to the infectious microorganism pulse oximetry i. noninvasive device attached to a finger, toe, nose, or earlobe that uses spectrophotometry to measure the amount of red and infrared light absorbed by oxygenated and unoxygenated hemoglobin in arterial blood to assess hemoglobin saturation end