S1 B - Oxygenation - Lecture notes 1 PDF

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oxygenation and respiratory care...

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S1 B - Oxygenation Common Respiratory Tests and Methods

Oxygenation Tests Pulse oximetry: A pulse oximeter is a device used to measure pulse rate and oxygen concentration in arterial blood (SaO2). A sensor is attached to the patient's finger, toe, nose, earlobe, or forehead. Accuracy is directly related to the perfusion of the probe area, a systolic blood pressure >90 mm Hg, and the hemoglobin level. Decreased levels correlate well with arterial oxygen levels and are used to trend oxygenation over time. Normal SaO2 values are 98%–100%. An SaO2 below 70% is life-threatening. Arterial blood gas: A radial or femoral artery is punctured to obtain arterial blood. Tests measure the oxygen concentration in the blood, the hydrogen ion concentration (pH), partial pressure of carbon dioxide (PaCO2), and the partial pressure of oxygen (PaO2).

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Normal values are as follows: • pH 7.35–7.45 • PaCO2 35–45 mm Hg • PaO2 80–100 mm Hg • SaO2 95%–100%

Pulmonary Function Tests Pulmonary function tests measure lung volume (the amount of air moving into and out of the lungs) and capacity (how much air the lungs can hold). Respiratory therapists usually conduct these tests.

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Imaging •

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Chest X-ray examination: Usually posteroanterior and lateral films are taken to adequately visualize all of the lung fields. A radiograph of the thorax is used to observe the lung fields for fluid, infiltrates (e.g., pneumonia), masses (e.g., lung cancer), fractures, pneumothorax, and other abnormal processes. Computed tomography (CT) scan: A CT scan provides visualization of fine detail of the lungs and other structures in the thorax. It is often used as part of the assessment of patients with pneumonia, lung masses, and suspected pulmonary emboli. Ventilation/perfusion (nuclear medicine) lung scan: This scan is used to detect pulmonary emboli. The results from two separate scans are compared: the perfusion scan uses an injected radioactive tracer to measure pulmonary blood flow, and the ventilation scan shows the pulmonary distribution of a different inhaled tracer. Mismatches (areas of ventilation without corresponding perfusion or blood flow) indicate pulmonary emboli.

Methods of Obtaining Respiratory Specimens for Analysis

Sputum Sample: Sputum is mucus from the respiratory system that is expectorated through the mouth. Sputum specimens are obtained when the patient coughs up sputum from the bronchi and trachea; specimens are easier to obtain in the morning when the secretions are coughed up upon awakening.

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Sputum tests include: A. Sputum culture and sensitivity (C and S) test, used to identify a specific microorganism growing in the sputum and to identify drug resistance and sensitivities; B. Sputum for acid-fast bacillus (AFB), a test used to screen for the presence of AFB for detection of TB by early-morning specimens on three consecutive days; and C. Sputum for cytology, used to identify abnormal lung cancer and differentiates the type of cancer cells (small cell, oat cell, large cell).

Tracheal aspiration via endotracheal tube in intubated patients: Secretions are collected by passing a flexible suction catheter through the endotracheal tube.

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Bronchoscopy: A narrow, flexible, fibreoptic scope is passed into the trachea and bronchi to enable visual examination of the tracheobronchial tree. The procedure is performed to obtain fluid, sputum, or biopsy samples, and to remove mucous plugs or foreign bodies.

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Thoracentesis: This involves surgical perforation of the chest wall and pleural space with a needle to aspirate fluid for diagnostic or therapeutic purposes or to remove a specimen for biopsy. The procedure is performed using aseptic technique and local anaesthetic. The patient usually sits upright with the anterior thorax supported by pillows or an overbed table.

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Nasopharyngeal aspirate or swab:  

This swab is used to detect respiratory viruses. Aspirates are the best specimens from young children, whereas swabs can be used for obtaining samples from older children and adults.

Nursing Diagnostic Process Assessment Activities

Defining Characteristics

Ask patient or family about patient's mood, attentiveness, memory, and activity level.

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Confusion Decreased activity Fatigue Irritability Restlessness Sleepiness

Observe patient's respirations.

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Dyspnea Impaired gas exchange related to collapsed alveoli Nasal flaring Tachypnea Use of accessory muscles

Inspect skin and mucous membranes.

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Diaphoresis Pallor Moist skin

Auscultate chest.

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Decreased respiratory excursion Abnormal, distant lung sounds

Nursing Diagnosis Impaired gas exchange related to decreased lung expansion

Patients with impaired oxygenation require a nursing care plan directed toward meeting the actual or potential oxygenation needs of the patient. For example, the goal of maintaining a patent airway can be evaluated by specific outcomes for the patient. These might include the following expected outcomes:    

Patient's lungs are clear to auscultation. Patient achieves maintenance and promotion of bilateral lung expansion. Patient coughs productively. Tissue oxygenation (SaO2) is maintained or improved

Methods of Oxygen Delivery  

Oxygen delivery devices can be considered low-flow or high-flow systems. Low-flow devices such as nasal cannulas, simple face masks, and reservoir masks provide oxygen in concentrations that vary with the patient's respiratory pattern.

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High-flow devices deliver oxygen rates above the normal inspiratory flow rate and thus provide a fixed FiO2 (fraction of inspired oxygen) regardless of the patient's inspiratory flow and breathing pattern. The Venturi mask is an example of a high-flow device.

Nasal Cannula      

A nasal cannula is a low-flow device used for oxygen delivery. The two cannulas, approximately 1.5 cm long, protrude from the centre of a disposable tube and are inserted into the nares. Oxygen is delivered via the cannulas with a flow rate of up to 6 L/minute. Flow rates greater than 4 L/minute are not often used because of the drying effect on the mucosa and the relatively little increase in delivered oxygen concentration. Know what flow rate produces a given percentage of inspired oxygen concentration Also be alert for skin breakdown over the ears and in the nares from too tight an application of the nasal cannula.

Approximate FiO2 with Different Oxygen Delivery Devices**********!!!!!!!!! Oxygen Delivery Device Nasal cannula

Simple face mask

Venturi mask

Required Litre Flow (L/minute)

Approximate Percent Oxygen

1–2

24–28

3–4

32–36

5–6

40–44

5–6

40

6–7

50

7–8

60

4

24–28

8

35–40

12

50–60

Oxygen Masks    

The simple face mask is used for short-term oxygen therapy. It fits loosely and delivers oxygen concentrations from 40% to 60%. The mask is contraindicated for patients with carbon dioxide retention because retention can be worsened. The partial rebreathing mask and the non-rebreathing mask are low-flow devices with a reservoir bag.

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The partial rebreather mask provides an oxygen concentration of 40% to 70% with a minimum flow rate of 10 L/minute The non-rebreather provides a high concentration of oxygen at 60% to 80% with a minimum flow rate of 10 L/minute Oxygen flows into the reservoir bag and mask during inhalation; one-way valves on the nonrebreather mask prevent expired air from flowing back into the bag. Frequently inspect the bag to make sure it is inflated. If it is deflated, the patient may be breathing large amounts of exhaled carbon dioxide. The Venturi mask, a high-flow device, can be used to deliver oxygen concentrations of 24% to 60% with oxygen flow rates of 4 to 12 L/minute. This mask entrains room air to achieve a consistent and precise oxygen concentration. The Venturi mask is helpful for patients with COPD who need low, constant oxygen concentrations.

Reading 2 (pg’s 924-935)

Oxygen Therapy         

Oxygen therapy is widely available and used in a variety of settings to relieve or prevent tissue hypoxia The goal of oxygen therapy is to prevent or relieve hypoxia. Any patient with impaired tissue oxygenation can benefit from controlled oxygen administration. Oxygen is not a substitute for other treatment, however, and should be used only when indicated. Oxygen should be treated as a drug. It has dangerous side effects, such as atelectasis or oxygen toxicity As with any drug, the dosage or concentration of oxygen should be continuously monitored. Routinely check the physician's orders to verify that the patient is receiving the prescribed oxygen concentration. The seven rights of medication administration also pertain to oxygen administration !!! Left untreated, hypoxia can produce cardiac dysrhythmias and death. Presence of airway secretions decreases the effectiveness of oxygen delivery.

Methods of Oxygen Delivery 

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Oxygen delivery devices can be considered low-flow or high-flow systems. Low-flow devices such as nasal cannulas, simple face masks, and reservoir masks provide oxygen in concentrations that vary with the patient's respiratory pattern High-flow devices deliver oxygen rates above the normal inspiratory flow rate and thus provide a fixed FiO2 (fraction of inspired oxygen) regardless of the patient's inspiratory flow and breathing pattern The Venturi mask is an example of a high-flow device

Nasal Cannula     

A nasal cannula is a low-flow device used for oxygen delivery The two cannulas, approximately 1.5 cm long, protrude from the centre of a disposable tube and are inserted into the nares Oxygen is delivered via the cannulas with a flow rate of up to 6 L/minute. Flow rates greater than 4 L/minute are not often used because of the drying effect on the mucosa and the relatively little increase in delivered oxygen concentration. Also be alert for skin breakdown over the ears and in the nares from too tight an application of the nasal cannula.

If oxygen flow rate is >4 L/minute, determine the need for humidification.

Home Oxygen Therapy  

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Indications for home oxygen therapy include a PaO2 of 55 mm Hg or less or an SaO2 of 88% or less on room air at rest, on exertion, or with exercise. Patients with a PaO2 from 56 to 59 mm Hg may receive oxygen if there is also evidence of cor pulmonale, pulmonary hypertension, erythrocytosis, central nervous system dysfunction, impaired mental status, or increasing hypoxemia with exertion. Home oxygen therapy has a beneficial effect for patients with chronic cardiopulmonary diseases. This therapy improves patients' exercise tolerance and fatigue levels and in some situations assists in the management of dyspnea. When home oxygen is required, it is usually delivered by nasal cannula. When a patient has a permanent tracheostomy, however, a T tube or tracheostomy collar is necessary. Three types of oxygen are used: compressed oxygen, liquid oxygen and oxygen concentrators. Patients requiring home oxygen need extensive teaching to be able to continue oxygen therapy at home efficiently and safely

Restoration of Cardiopulmonary Functioning    

If a patient's hypoxia is severe and prolonged, cardiac arrest may result. A cardiac arrest is a sudden cessation of cardiac output and circulation. When this occurs, oxygen is not delivered to tissues, carbon dioxide is not transported from tissues, tissue metabolism becomes anaerobic, and metabolic and respiratory acidosis occurs. Permanent heart, brain, and other tissue damage occurs within four to six minutes.

Home Oxygen Systems Primary Use Compressed Gas Cylinders

Advantages

Disadvantages

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Intermittent therapy Used for exercise or sleep only

100% oxygen, relatively inexpensive, no loss of gas during storage, relatively portable, delivery of up to 15 L/minute

Bulky, possibly unsightly, frequent refilling necessary with continuous use

100% oxygen, conveniently portable, portable units refilled at home, delivery of up to 6 L/minute

Usually weekly delivery necessary for refill, evaporates if not used, potential for frostbite at connections and if liquid is spilled

Fixed monthly cost, minimal interruption of household by supplier, no refills of “main tank,” most units with delivery of up to 4 or 5 L/minute

Oxygen concentration decreases as litre flow increases (usually 85%–90%), power supply needed, electric bill increase, second system needed for portability, usually E tank gas cylinders

Liquid Oxygen Systems 

Used with active patients

Oxygen Concentrators 

Homebound patients with limited mobility inside or outside home

Restorative and Continuing Care  

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Restorative and continuing care may emphasize cardiopulmonary reconditioning as a structured rehabilitation program. Cardiopulmonary rehabilitation is actively helping the patient to achieve and maintain an optimal level of health through controlled physical exercise, nutrition counselling, relaxation and stress management techniques, prescribed medications and oxygen, and compliance. As physical reconditioning occurs, the patient's complaints of dyspnea, chest pain, fatigue, and activity intolerance should decrease. The patient's anxiety, depression, or somatic concerns also often decrease. The patient and the rehabilitation team define the goals of rehabilitation.

Hydration     

Maintenance of adequate systemic hydration keeps mucociliary clearance normal. In patients with adequate hydration, pulmonary secretions are thin, white, watery, and easily removable with minimal coughing. Excessive coughing to clear thick, tenacious secretions is fatiguing and energy depleting. The best way to maintain thin secretions is to provide a fluid intake of 1500 to 2000 mL/day unless contraindicated by cardiac status. The colour, consistency, and ease of secretion expectoration can determine the adequacy of hydration.

Breathing Exercises  

Breathing exercises include techniques to improve ventilation and oxygenation. The three basic techniques are deep breathing and coughing exercises, pursed-lip breathing, and diaphragmatic breathing.

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Deep breathing and coughing exercises are routine interventions for postoperative patients

Coughing Techniques      

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Coughing is effective for maintaining a patent airway. Coughing enables the patient to remove secretions from both the upper and lower airways. The normal series of events in the cough mechanism are deep inhalation, closure of the glottis, active contraction of the expiratory muscles, and glottis opening. Deep inhalation increases the lung volume and airway diameter, allowing the air to pass through partially obstructing mucous plugs or other foreign matter. The effectiveness of coughing is evaluated by sputum expectoration, the patient's report of swallowed sputum, or clearing of adventitious sounds by auscultation. Patients with chronic pulmonary diseases, upper respiratory tract infections, and lower respiratory tract infections should be encouraged to deep-breathe and cough at least every two hours while awake. Patients with a large amount of sputum should be encouraged to cough every hour while awake and every two to three hours while asleep until the acute phase of mucus production has ended. Coughing techniques include deep breathing and coughing for the postoperative patient, cascade, huff, and quad coughing.

The Cascade Cough   

The patient takes a slow, deep breath and holds it for two seconds while contracting expiratory muscles. Then the patient opens the mouth and performs a series of coughs throughout exhalation, thereby coughing at progressively lowered lung volumes. This technique promotes airway clearance and a patent airway in patients with large volumes of sputum

The Huff Cough  

Stimulates a natural cough reflex and is generally effective only for clearing central airways. While exhaling, the patient opens the glottis by saying the word “huff.” With practice, the patient inhales more air and may be able to progress to the cascade cough.

The Quad Cough  

Technique is used for patients without abdominal muscle control, such as those with spinal cord injuries. While the patient breathes out with a maximal expiratory effort, the patient or nurse pushes inward and upward on the abdominal muscles toward the diaphragm, causing the cough.

Respiratory Muscle Training    

Respiratory muscle training improves muscle strength and endurance, resulting in improved activity tolerance. Respiratory muscle training may prevent respiratory failure in patients with COPD. One method for respiratory muscle training is the incentive spirometer resistive breathing device (ISRBD). Resistive breathing is achieved by placing a resistive breathing device into a volume-dependent incentive spirometer.

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Muscle training is achieved when the patient uses the ISRBD on a scheduled routine (e.g., twice a day for 15 minutes or four times a day for 15 minutes)....