NCLEX: Respiratory

Following lung surgery, a chest tube is inserted into the pleural space to create a negative vacuum to re-inflate the lung and prevent air from re-entering the space.

A client with a chest tube should be assessed for signs of air/fluid in the chest (eg, diminished breath sounds), excessive drainage (>100 mL/hr), pain, and infection at the drainage site. The collection chamber should be inspected every hour for the first 8 hours following surgery, then every 8 hours until it is removed. Excess drainage of frank red blood is indicative of hemorrhage and must be managed immediately. The priority action is to contact the health care provider for further management.

In clients with asthma, the airways are chronically inflamed with varying degrees of airway obstruction that can be exacerbated by exposure to triggering agents. Common asthma triggers include:

Allergens: Dander (eg, cat, dog), dust mites, pollen Drugs: Beta blockers; nonsteroidal anti-inflammatory agents, including aspirin Environmental: Chemicals, sawdust, soaps/detergents Infectious: Upper respiratory infections Intrinsic: Emotional stress, gastrointestinal reflux disease Irritants: Aerosols/perfumes, cigarette smoke (including secondhand smoke), dry/polluted air

Clients should be taught to understand that symptoms of pneumonia (eg, cough, sputum production, shortness of breath, fatigue, and activity intolerance) remain after discharge even though the bacteria are no longer present and will dissipate over a 2-4 week period, depending on current health status and preexisting conditions. Discharge teaching includes the following instructions:

Avoid the use of over-the-counter cough suppressant medicines. Unless prescribed by the HCP, cough suppressants are avoided as they impair secretion clearance, especially in clients with chronic bronchitis. Schedule a follow-up with the HCP and chest x-ray. Follow-up is needed at about 2 weeks after completion of antibiotic therapy. X-ray may be needed at a later time in certain high-risk clients to make sure the pneumonia is resolved with no underlying cancer. Use a cool mist humidifier in your bedroom at night. Humidifiers keep mucus membranes moist, maintain effectiveness of the mucociliary escalator, and facilitate expectoration of mucus. A warm bath also loosens the secretions. Continue using the incentive spirometer at home. Deep breathing and coughing promote lung expansion, ventilation, oxygenation, and airway clearance. Drink 1-2 liters of water a day to help thin secretions and facilitate mobilization. Limit caffeine and alcohol as they can dry mucus membranes due to diuretic effects. Notify the HCP of any increase in symptoms (eg, shortness of breath, cough, sputum production, chest pain, fever, confusion). Avoid all tobacco products and second-hand smoke as these irritate the airways and impair mucociliary clearance and oxygenation. Eat a balanced diet, increase activity slowly over about 2 weeks, and take rest periods when needed to help maintain resistance to infection.

A peak flow meter is a portable, inexpensive, hand-held device used to measure the client's ability to push air out of the lungs. Flow meters are available in low ranges for measuring smaller volumes and for small children, and in a standard range for older children, teenagers, and adults. To obtain the most accurate readings to help guide, maintain, and evaluate treatment in clients with moderate to severe asthma, the procedure is carried out in the following order:

Before using, slide the indicator on the numbered scale on the flow meter to 0 or lowest number and instruct the client to stand or sit as upright as possible Instruct the client to breathe in deeply, place the mouthpiece in the mouth, and the close lips tightly around it to form a seal Instruct the client to exhale as quickly and forcibly as possible and note the reading on the numbered scale Repeat the procedure 2 more times with a 5-10-second rest period between exhalations Record the highest reading achieved (personal best)

diphenhydramine

Benadryl Antihistamine H1 blocker prototype: used in hayfever, motion sickness, dystonias. Tox: antimuscarinic, anti−alpha, sedative OD on sleeping pill. Hot skin, blurry vision, urinary retention, dry mucous membranes, tachycardia, decreased bowel sounds. What is the pill?

Anaphylactic shock has an acute onset, and manifestations usually develop quickly (20-30 minutes). It is caused by a systemic IgE-mediated hypersensitivity allergic reaction to drugs, foods, and venom. Anaphylactic shock results in hypotension and respiratory manifestations, including laryngeal edema (from inflammation) and bronchoconstriction (primarily from release of histamine); these can lead to cardiac and respiratory arrest. The management of anaphylactic shock includes:

Call for help (activate emergency management systems) - first action. Maintain airway and breathing - administer high-flow O2 via non-rebreather mask. Epinephrine, intramuscular - the drug of choice and should be given next. Epinephrine stimulates both alpha- and beta-adrenergic receptors, dilates bronchial smooth muscle (beta 2), and provides vasoconstriction (alpha 1). The IM route is better than the subcutaneous route. The dose should be repeated every 5-15 minutes if there is no response. Elevate the legs. Volume resuscitation with IV fluids. Bronchodilator such as albuterol is administered to dilate the small airways and reverse bronchoconstriction. Antihistamine (diphenhydramine) is administered to modify the hypersensitivity reaction and relieve pruritus. Corticosteroids (methylprednisolone [Solu-Medrol]) are administered to decrease airway inflammation and swelling associated with the allergic reaction

Pneumonia is an acute infection of the lungs. Findings in a client with pneumonia include:

Crackles - Fine or coarse crackling sounds caused by air passing through alveoli and small airways obstructed with mucus. Fever, chills, productive cough, dyspnea, and pleuritic chest pain. Increased vocal/tactile fremitus - Transmission of palpable vibrations (fremitus) is increased when transmitted through consolidated versus normal lung tissue. Bronchial breath sounds in peripheral lung fields - High-pitched, harsh sounds conducted through consolidated lung tissue, which are abnormal when heard in an area distant from where normally heard (ie, trachea); this finding can be an early sign of pneumonia. Unequal chest expansion - Decreased expansion of affected lung on palpation Dullness - Percussion of medium-pitched sounds over consolidated lung tissue (pneumonia) or fluid-filled space (eg, pleural effusion, a complication of pneumonia)

A thoracentesis involves the insertion of a large-bore needle through an intercostal space to remove excess fluid. The procedure has the following advantages:

Diagnostic - analysis of fluid to diagnose the underlying cause of the pleural effusion (eg, infection, malignancy, heart failure), including cytology, bacterial culture, and related testing Therapeutic - removal of excess fluid (>1 L) improves dyspnea and client comfort Complications from insertion of the needle and removal of large amounts of fluid include iatrogenic pneumothorax, hemothorax, pulmonary edema, and infection. After the procedure, the nurse assesses for pain and difficulty breathing; monitors vital signs and oxygen saturation; and observes for changes in respiratory rate and depth, symmetry of chest expansion, and breath sounds. If any abnormalities are noted, a post-procedure chest x-ray is obtained. Decreased chest expansion with inspiration and breath sounds on the affected side, tachypnea, tracheal deviation to the opposite side, and hyperresonance (air) on the affected side are manifestations of a pneumothorax. These should be reported immediately.

In pneumonia, the lung is filled with infectious debris and exudate. This increase in secretions and a simultaneous decrease in mucociliary clearance result in possible airway obstruction. Interventions to facilitate airway clearance include the following:

Hydration - IV fluids, oral intake (2-3 L/day), and respiratory humidification help thin secretions, maintain moisture of mucous membranes, and promote mucociliary clearance. Huff coughing technique - the most effective way to raise secretions from the lower to the upper airway for expectoration. If pain limits deep breathing and coughing, analgesia can be prescribed. Chest physiotherapy (percussion, vibration, and postural drainage) to open airways and break up thickened secretions. Fowler's position - Sitting upright with the head of the bed at 45-60 degrees promotes lung expansion and facilitates coughing and secretion removal.

Obstructive sleep apnea (OSA) is characterized by partial or complete airway obstruction during sleep that occurs from relaxation of the pharyngeal muscles. The result is repeated episodes of apnea (≥10 seconds) and hypopnea (≤50% normal ventilation), which cause hypoxemia and hypercarbia. Common symptoms include frequent periods of sleep disturbance, snoring, morning headache, daytime sleepiness, difficulty concentrating, forgetfulness, mood changes, and depression.

Interventions include: Continuous positive airway pressure device at night to keep the structures of the pharynx and tongue from collapsing backward. Limiting alcohol intake at bedtime as it can cause muscles of the oral airway to relax and lead to airway obstruction. Weight loss and exercise can reduce snoring and sleep apnea-associated airway obstruction. Obesity contributes to the development of OSA. Avoiding sedating medications (eg, benzodiazepines, sedating antidepressants, antihistamines, opiates) as they may exacerbate OSA and worsen daytime sleepiness

The nurse prioritizes nursing actions for the hospitalized client with pneumonia in the following order:

Oxygen per nasal cannula at 4 L/min - This client is in respiratory distress (respirations 30/min, dusky nail beds). Oxygen administration is the priority action. NS at 125 mL/hr - Most elderly clients with pneumonia present with dehydration (dry mucus membranes, low blood pressure). Initiation of IV fluids is important to thin secretions, facilitate expectoration of mucus, and provide access for antibiotic therapy. Blood cultures x 2 for temperature >102 F (38.9 C) - Cultures should always be drawn before antibiotic administration, as these can be inaccurate if drawn afterward. Identifying the causative pathogen is necessary to ensure that the appropriate antibiotic is prescribed. Cultures are drawn x 2 (from 2 different venipuncture sites) to rule out contaminants. Levofloxacin 750 mg IV every 24 hours - Levofloxacin (Levaquin) is a fluoroquinolone antibiotic recommended for the treatment of pneumococcal pneumonia. Antibiotics should be administered as soon as possible after the pneumonia diagnosis is made and cultures have been drawn. Incentive spirometer every 2 hours - Deep breathing can be performed after the initiation of antibiotics. Incentive spirometry increases alveolar expansion, facilitates removal of secretions, and prevents atelectasis.

Acute severe asthma exacerbations (status asthmaticus) occur when severe airway obstruction and lung hyperinflation (air trapping) persist despite aggressive treatment with bronchodilators and corticosteroid therapy. Clinical manifestations indicating impending respiratory failure include:

PaCO2 ≥45 mm Hg (6.0 kPa): Indicates hypercapnia and hypoventilation resulting from fatigue and labored breathing. As initial tachypnea subsides and respiratory rate returns to normal, PaCO2 rises and respiratory acidosis develops. PaO2 ≤60 mm Hg (8.0 kPa): Indicates hypoxemia resulting from increased work of breathing, decreased gas exchange (hyperinflation and air trapping), and inability of the lungs to meet the body's oxygen demand. Paradoxical breathing (ie, abnormal inward movement of the chest on inspiration and outward movement on expiration): Indicates diaphragm muscle fatigue and use of respiratory accessory muscles. Mental status changes (eg, restlessness, confusion, lethargy, drowsiness): Sensitive indicators of hypoxemia and hypoxia. Absence of wheezing and silent chest (ie, no sound of air movement on auscultation): Ominous signs indicating severe hyperinflation and air trapping in the lungs. Single-word dyspnea: Inability to speak >1 word before pausing to breathe due to shortness of breath

The nurse activates a rapid response because the client is in acute respiratory distress. While waiting for the team, the nurse should implement the following actions in order:

Place in high Fowler's position - quickly maximizes ability to expand lungs, promotes oxygenation, and helps to decrease risk of further aspiration Perform oropharyngeal suctioning - the priority is clearing the airway after the client has been placed in a position that prevents further aspiration Administer 100% oxygen by nonrebreather mask - corrects hypoxemia/hypoxia once the airway has been cleared to allow passage of oxygen. The nurse has already gathered focused assessment data and determined the need for emergent oxygen delivery (eg, tachycardia, tachypnea, hypoxia, cyanosis, decreased level of consciousness). Assess lung sounds - determines air movement and presence of adventitious sounds (eg, crackles, wheezing, stridor) that can indicate obstruction, secretions, atelectasis, or fluid. This assessment is performed once emergency measures are in place (eg, oxygen) and the client has been stabilized. Notify the primary HCP - to report the situation and assessment data To provide more efficient care, any of these tasks can be delegated to a second RN.

To help identify the presence of elevated levels of CO in the home, the nurse can ask about the following:

Similar symptoms in other family members that developed at the same time. A sick indoor pet with sick family members (pets do not share viral illnesses or eat the same food as people). Heating and cooking sources (fuel-burning appliances); the risk of CO toxicity from malfunctioning heaters and inadequate ventilation increases during the fall and winter months.

Anaphylactic shock has an acute onset (20-30 minutes) caused by a systemic IgE-mediated hypersensitivity allergic reaction to drugs (eg, antibiotics), foods (eg, shellfish, peanuts), diagnostic agents (eg, contrast), biologic agents (eg, blood, vaccines), and venom (eg, bees, snakes) and results in circulatory failure, laryngeal edema, and severe bronchoconstriction. Management of anaphylactic shock includes:

Stop the infusion that is causing the reaction and call for help (eg, rapid response team). Ensure patent airway, then administer oxygen via a high-flow nonrebreather mask and prepare for intubation if needed. Give epinephrine intramuscularly. Epinephrine counteracts the effect of the histamines released, dilating bronchial smooth muscles and providing vasoconstriction. Most deaths from anaphylaxis are due to delaying epinephrine. Maintain blood pressure with normal saline IV fluid. Administer adjunctive therapies: Bronchodilators (eg, albuterol) to dilate the small airways and reverse bronchoconstriction, antihistamines (eg, diphenhydramine) to modify the hypersensitivity reaction, and corticosteroids (eg, methylprednisolone) to decrease airway inflammation and swelling associated with the allergic reaction. Continue to reassess vital signs for any changes

Carbon monoxide (CO) is a toxic inhalant that enters the blood and binds more readily to hemoglobin than oxygen does. When hemoglobin is saturated with CO, the pulse oximeter reading is falsely normal as conventional devices detect saturated hemoglobin only and cannot differentiate between CO and oxygen.

The diagnosis of CO poisoning is often missed in the emergency department because symptoms are nonspecific (eg, headache, dizziness, fatigue, nausea, dyspnea) and the pulse oximeter reading often appears within normal limits. A serum carboxyhemoglobin test is needed to confirm the diagnosis. Normal values are <5% in nonsmokers and slightly higher (<10%) in smokers. A client with CO poisoning requires immediate administration of 100% oxygen to increase the rate at which CO dissipates from the blood to prevent tissue hypoxia and severe hypoxemia.

During the initial postoperative period,

a client needs respiratory interventions to keep the lungs expanded and prevent atelectasis and postoperative pneumonia. Atelectasis is maximal during the second postoperative night. Clients can be asymptomatic or have increased work of breathing, hypoxia, and basal crackles. Postoperative pain, opioid respiratory depression, limited mobility, and reluctance to take a deep breath due to anticipated pain contribute to postoperative atelectasis. The elderly and postoperative abdominal and thoracic surgery clients are at increased risk for atelectasis. The incentive spirometer encourages the client to breathe deeply with maximum inspiration. This action improves ventilation and oxygenation by expanding the lungs, encourages coughing, and prevents or improves atelectasis. It is the most appropriate prescription for this client.

Chest tubes

are indicated to drain air or fluid from the pleural space and reestablish negative pressure, which allows for proper lung expansion. When the lung has reexpanded or fluid drainage is no longer needed, the chest tube can be discontinued. The client should be given an analgesic 30-60 minutes prior to the procedure. A suture removal kit, petroleum gauze, and occlusive dressing supplies will be needed. The client should be instructed to take a deep breath, hold it, and bear down (Valsalva maneuver) while the tube is being removed. This will prevent air from being pulled back into the pleural space and possibly causing a pneumothorax. A post-procedure chest x-ray must be performed to ensure there is no reaccumulation of air or fluid in the pleural space.

Some clients with COPD

breathe in response to low arterial oxygen levels (hypoxemia). If they receive more oxygen than they need to maintain an arterial saturation, the increased level can decrease the drive to breathe. Therefore, supplemental oxygen should be administered in the lowest concentration possible to maintain a pulse oxygen saturation of 90%-93% or a PaO2 of 60-70 mm Hg. When oxygen is delivered via a nasal cannula, the concentration of inspired oxygen will vary with changes in ventilation and respiratory pattern. In a deep sleep, with smaller tidal volumes and decreased respiratory rate, the concentration of inspired oxygen increases. In some clients with COPD, too high a level of inspired oxygen can depress the respiratory drive to breathe, causing alveolar hypoventilation. If the saturation of a pt remained constant at 91% while the sleeping soundly, the nurse should remove the nasal oxygen, recheck the saturation, and re-evaluate. Removing the supplemental oxygen may actually increase the reading.

Clients with acute pancreatitis

can develop respiratory complications including pleural effusions, atelectasis, and acute respiratory distress syndrome (ARDS). These complications are often due to activated pancreatic enzymes and cytokines that are released from the pancreas into the circulation and cause focal or systemic inflammation. ARDS is the most severe form of these complications and can rapidly progress to respiratory failure within a few hours. Therefore, the presence of inspiratory crackles in this client could indicate early ARDS and needs to be assessed further for progression.

Immediately following a thoracotomy

chest tube drainage (50-500 mL for the first 24 hours) is expected to be sanguineous (bright red) for several hours and then change to serosanguineous (pink) followed by serous (yellow) over a period of a few days. A rush of dark bloody drainage from the chest tube when the client is turned following a period of minimal drainage is most likely related to retained blood due to a partial blockage in the tube. Bright red drainage indicates active bleeding and would be of immediate concern.

The incentive spirometer

is a handheld, inexpensive breathing device. It encourages the client to breathe deeply with maximum inspiration, which improves ventilation and oxygenation and encourages coughing. The incentive spirometer is used to prevent or improve atelectasis in clients who are postoperative, have respiratory problems (eg, pneumonia), or have experienced trauma.

Risks associated with suctioning include

hypoxemia, microatelectasis, and cardiac dysrhythmias. Suctioning removes secretions and oxygen. To minimize both the amount of oxygen removed and mucosal trauma, suction is applied when removing, not inserting, the catheter into the artificial airway. If secretions are thick and difficult to remove, increasing hydration, not suctioning time, is indicated. Aerosols of sterile normal saline or mucolytics such as acetylcysteine (Mucomyst) administered by nebulizer can also be used to thin the thick secretions, but water should not be used. Aerosol therapy may induce bronchospasm in certain individuals and can be relieved by use of a bronchodilator (albuterol).

Allergy skin testing

involves introducing common allergens (antigen) into the skin surface and then observing the site for swelling and induration, which indicate that the client is allergic to the antigen. To ensure an accurate result, the client should avoid taking any antihistamines such as diphenhydramine and loratadine for a week or more prior to the test. Antihistamines block mast cell release of histamines that are responsible for allergic symptoms. Systemic corticosteroids, which are used to treat the inflammatory component of asthma, can interfere with the accuracy of allergy skin testing as well; therefore, the use of these medications should be assessed. *Acetaminophen will not interfere with allergy skin testing, but nonsteroidal anti-inflammatory drugs and aspirin may be included in the list of medications to avoid.

Cystic fibrosis (CF),

is a defective protein responsible for transporting sodium and chloride causes the secretions from the exocrine glands to be thicker and stickier than normal. The sticky respiratory secretions lead to the inability to clear the airway and a chronic cough. The client eventually develops chronic lung disease (bronchiectasis) and is at risk for recurrent lung infections. These clients are also at risk for rupture of the damaged alveoli, which results in sudden-onset pneumothorax. Findings of pneumothorax include sudden worsening of dyspnea, tachypnea, tachycardia, and a drop in oxygen saturation. Because many of these findings can be seen with lung infection, a sudden drop in oxygen saturation could be the only early clue. The client with CF will often have a decreased pulse oximetry reading due to the chronicity of the disease process and damage to the lungs; however, a reading of 90% requires urgent intervention. When addressing the multiple needs of a client with cystic fibrosis, airway and oxygen saturation are the priorities. Pneumothorax can be a complication of cystic fibrosis.

An endoscopic bronchoscopy

is a procedure in which the bronchi are visualized with a flexible fiberoptic bronchoscope that is passed down through the nose (or through the mouth, or endotracheal or tracheostomy tube). The client receives mild sedation (eg, midazolam) to provide relaxation and promote comfort. A topical anesthetic (eg, lidocaine, benzocaine) is applied to the nares and throat to suppress the gag and cough reflexes, prevent laryngospasm, and facilitate passage of the scope. The procedure is done to diagnose, obtain tissue samples for biopsy, lavage, and to remove secretions (mucus plugs), foreign objects, or abnormal tissue with a laser. Blood-tinged sputum is common and can occur from inflammation of the airway, but hemoptysis of bright red blood can indicate hemorrhage, especially if a biopsy was performed. Other complications include hypoxemia, hypercarbia, hypotension, laryngospasm, bradycardia, pneumothorax (rare), and adverse effects from medications used before and during the procedure.

Carbon monoxide (CO)

is a tasteless, colorless, odorless gas. It is a byproduct of the incomplete burning of carbon-containing materials (eg, oil, kerosene, coal, wood). CO toxicity is most often associated with smoke inhalation during a structure fire. Other potential sources include gas and fuel oil heating systems, gas hot water heaters, coal or wood stoves, gas grills, and engine exhaust. Clients who are victims of a house fire or those found in a closed garage with the car running are easily identified because they have a known history. Most clients who come to the emergency department with CO toxicity have vague, nonspecific signs and symptoms and the diagnosis is often missed. It is essential to ask the right questions during the history to make an accurate diagnosis, initiate appropriate diagnostic testing and treatment, and prevent possible neurologic impairment associated with toxicity.

A pleural effusion

is an abnormal collection of fluid (>15-20 mL) in the pleural space between the parietal and visceral pleurae that prevents the lung from expanding fully. This results in decreased lung volume, atelectasis, and ineffective gas exchange. Clients commonly have dyspnea on exertion and non-productive cough. Examination shows diminished breath sounds, dullness to percussion, and decreased tactile fremitus. If the effusion is large, the trachea (mediastinum) is deviated to the opposite side. Palpable vibration felt on the chest wall is known as fremitus. Sound travels faster in solids (consolidation) than in an aerated lung, resulting in increased fremitus in pneumonia. The presence of egophony, bronchophony, or whispered pectoriloquy also suggests a consolidative process. Fluid or air outside the lung interrupts the transmission of sound, resulting in decreased fremitus in pleural effusion and pneumothorax.

Pleurisy

is characterized by stabbing chest pain that usually increases on inspiration or with cough. It is caused by inflammation of the visceral pleura (over the lung) and the parietal pleura (over the chest cavity). The pleural space (between the 2 layers) normally contains about 10 mL of fluid to help the layers glide easily with respiration. When inflamed, they rub together, causing pleuritic pain. A pleural friction rub is auscultated in the lateral lung fields over the area of inflammation. The sound is produced by the 2 layers rubbing together and can indicate pleurisy, a complication of pneumonia. It is characterized by squeaking, crackling, or the sound heard when the palm is placed over the ear and the back of the hand is rubbed with the fingers. Complications of pneumonia are more prevalent in elderly clients with underlying chronic disease.

Acute respiratory failure (ARF)

is defined as inadequate gas exchange that is intrapulmonary (pneumonia, pulmonary embolism) or extrapulmonary (head injury, opioid overdose) in origin. Respiratory failure associated with an alteration in O2 transfer or absorption is type I hypoxemic failure (eg, acute respiratory distress syndrome, pulmonary edema, shock). Respiratory failure associated with carbon dioxide (CO2) retention is type II hypercapnic, or ventilatory failure (eg, chronic obstructive pulmonary disease, myasthenia gravis, flail chest). ARF is a potential complication of major surgical procedures, especially those involving the thorax and abdomen, as in this client. ABG values that indicate the presence of ARF are PaO2 ≤60 mm Hg (8.0 kPa) or PaCO2 ≥50 mm Hg (6.67 kPa). ARF occurs quickly over time (minutes to hours), and so there is no physiologic compensation and pH is ≤7.30. Immediate intervention with high O2 concentrations is indicated, and noninvasive or invasive, positive-pressure mechanical ventilation may be necessary.

Airway clearance

is impaired with inadequate hydration. A fluid intake of 2,500-3,000 mL/day is recommended in clients with pneumonia, and additional fluids are needed to replace insensible losses associated with fever and tachypnea. Increasing oral and intravenous hydration helps to thin secretions and facilitate expectoration of mucus.

Iron deficiency anemia

is the most common chronic nutritional disorder in children. There are many risk factors for iron deficiency, including insufficient dietary intake, premature birth, delayed introduction of solid food, and consumption of cow's milk before age 1 year. One common cause in toddlers is excessive milk intake, over 24 oz/day. In addition to becoming overweight, toddlers who consume too much milk develop iron deficiency due to the likely exclusion of iron-rich foods in favor of milk, a poor source of available iron. Treatment of iron deficiency anemia includes oral iron supplementation and increased consumption of iron-rich foods (eg, leafy green vegetables, red meats, poultry, dried fruit, fortified cereal). It is also important to limit milk intake (16-24 oz/day) in toddlers to ensure a balanced diet.

Oxygen saturation

is the percentage of hemoglobin molecules in the blood carrying their full potential of oxygen. The partial pressure of oxygen (PaO2) is an indicator of tissue oxygenation, and arterial oxygen saturation (SaO2) is an indicator of arterial oxygenation; both are measured directly with arterial blood gases. SpO2 is an estimate of arterial saturation and is measured indirectly using a pulse oximeter device. SpO2 levels have been shown to correlate well with PaO2 values (ie, SpO2 >95% correlates to a PaO2 of 80-100 mm Hg; SpO2 ≤90% correlates to PaO2 <60 mm Hg). It is the preferred method for measuring saturation because accurate reading can be measured noninvasively. Pulse oximetry readings can be inaccurate if the sensor is loose, does not fit properly, or if circulation is impaired under the sensor site. The nurse should check for these factors before taking other actions.

An elevated carbon dioxide (CO2) level (normal: 35-45 mm Hg [4.7-6.0 kPa])

is usually an indicator of hypercapneic respiratory failure. The bilevel positive airway pressure (BIPAP) machine will provide positive pressure oxygen and expel CO2 from the lungs. A client showing signs of lethargy and confusion, which is usually a late indicator of respiratory decline, should be putt on the BIPAP machine as soon as possible.

Pulmonary embolism (PE)

is usually caused by a dislodged thrombus that travels through the pulmonary circulation, becomes lodged in a pulmonary vessel, and causes an obstruction to blood flow in the lung. The nursing diagnosis of impaired gas exchange involves an alteration in the normal exchange of oxygen and carbon dioxide at the alveolar-capillary membrane, resulting in inadequate oxygenation and hypoxemia (respiratory alkalosis, pO2 <80 mm Hg, restlessness, dyspnea, and tachycardia). Impaired gas exchange related to a ventilation-perfusion (V/Q) imbalance is the highest priority nursing diagnosis. It addresses the most basic physiologic need—oxygen. Clients will not survive without adequate oxygenation.

Central chemoreceptors

located in the respiratory center of the brain (medulla) respond to changes in blood carbon dioxide and hydrogen ions by either increasing or decreasing ventilation to normalize the pH. When the receptors sense a low pH (acidosis), ventilation increases to rid the body of excess carbon dioxide; when the receptors sense a high pH (alkalosis), ventilation decreases to retain carbon dioxide. Peripheral chemoreceptors located in the carotid and aortic bodies respond to low levels of oxygen and stimulate the respiratory center to increase ventilation. Many clients with COPD breathe because their oxygen levels are low rather than because carbon dioxide levels are high. This is commonly referred to as the hypoxemic drive. If they receive too high a level of inspired oxygen, this drive can be blunted. It is therefore important for these clients to receive a "guaranteed" amount of oxygen as an increase in inspired oxygen can decrease the drive to breathe. To promote adequate gas exchange, the nurse should use a high-flow Venturi mask to deliver a specified, guaranteed amount of oxygen. Because this device has a mechanism that controls the mixture of room air, the inspired oxygen concentration remains constant despite changes in respiratory rate, depth, or tidal volume. It is the most appropriate intervention to promote adequate gas exchange.

Normal adult ABG values at sea level are as follows:

pH 7.35-7.45 PaO2 80-100 mm Hg (10.7-13.3 kPa) PaCO2 35-45 mm Hg (4.66-5.98) Bicarbonate (HCO3-) 22-26 mEq/L (22-26 mmol/L) O2 Saturation (SaO2) 95%-99%

Ineffective airway clearance

which is the inability to clear secretions or obstructions from the respiratory tract to maintain a clear airway, is a priority ND as it poses the greatest threat to survival. The most common causes of respiratory complications in the immediate postoperative period include the following: Airway obstruction, which can be due to retained secretions or the tongue falling backward against the soft palate in sedated clients. Suctioning and an artificial oral airway can be used to prevent obstruction until the client becomes more responsive. Hypoxemia, which can be due to atelectasis from increased retained secretions or hypoventilation, aspiration, or bronchospasm. Pulse oximetry and supplemental oxygen are used to maintain pulse oximeter readings >92%; placing the client in side-lying position and administrating antiemetic medications help to decrease aspiration. Hypoventilation, which can be due to depression of the respiratory drive as a result of anesthesia, pain, and opioid analgesia.