Flashcards in 2. oxygen Deck (33):
Oxygen diffuses from the capillary through the capillary wall to the interstitial fluid. At this point, it diffuses through the membrane of the tissue cells, where it is used by the mitochondria for cellular respiration. The movement of carbon dioxide occurs by diffusion in the opposite direction – from cell to blood.
o Diffusion – higher concentration to lower concentration (either side)
After these tissue capillaries exchange, blood enters the systemic veins and travel to the pulmonary circulation. The oxygen concentration in blood within the capillaries of the lung is lower then in the lung air sacs (alveoli). Because of the concentration gradient, oxygen diffuses from the alveoli to the blood. Carbon dioxide, which has a higher concentration in the blood. Then, in the alveoli, diffuses from the blood into the alveoli. Movement of air in and out of the airways (ventilation) continually replenishes the oxygen and removes the carbon dioxide from the airways and lungs.
o Alveoli – covered in capillary bed with oxygen molecules
During inspiration, air flows from the environment into the trachea, bronchi, bronchioles, and alveoli. During expiration, alveolar gas travels the same route in reverse. Physical factors that govern airflow in and out of the lungs are collectively referred to as the mechanics of ventilation and include air pressure variances, resistance to airflow, and lung compliance.
Mechanism of ventilation
pressure changes with inhaling/exhaling (3 components)
3 components of Mechanism of ventilation *
1. air pressure variance
2. resistance to flow – determined by the diameter of the airway (conditions that can narrow diameter: smoking, collapsed lung)
3. compliance – either increased or decreased – how elastic the lungs are, how they recoil and expand
air pressure variance
- air flows from a region of higher pressure to a region of lower pressure. During inspiration, movement of the diaphragm and other muscles of respiration enlarges in the thoracic cavity and thereby lowers the pressure inside the thorax to a level below that of atmospheric pressure. As a result, air is drawn through the trachea and bronchi into the alveoli. During expiration, the diaphragm relaxes in the lungs recoil, resulting in a decrease in the size of thoracic cavity. The alveolar pressure, then exceeds atmospheric pressure, and air flows from the lungs into the atmosphere.
resistance to flow
resistance is determined chiefly by the radius or size of the airway through which the air is flowing. Any process that changes the bronchial diameter or width affect airway resistance and alters the rate of airflow for a given pressure gradient during respiration with increased resistance, greater than normal respiratory effort is required to achieve normal levels of ventilation.
- or distendability (elasticity), is the elasticity or expandability of the Lungs and thoracic structures. Compliance allows the lung volume to increase when the difference in pressure between the atmosphere and thoracic cavity (pressure gradient) causes air to flow again. Factors that determine lung compliance are the surface tension of the alveoli and the connective tissue of the lungs. Compliance is determined by examining the volume pressure relationship in the lungs in the thorax. Compliance is normal. If the lungs and thorax easily stretch and expand when pressure is applied. High or increase compliance occurs if the lungs have lost their elasticity in the thorax is over distended (emphysema). Low or decrease compliance occurs if the lungs and thorax are “stiff” conditions associated with decreased compliance include morbid obesity, pneumothorax, hemothorax, pleural effusion, pulmonary edema, atelectasis, pulmonary fibrosis, acute respiratory distress syndrome. Measurement of compliance is one method used to assess the progression and improvement in patients with acute respiratory distress syndrome. Lungs with decreased compliance require greater than normal energy expenditure by the patient to achieve normal levels of ventilation. Compliance is usually measured under static conditions.
- COPD – lungs injured so increase compliance; can get air in but CO2 can’t get out
- Decreased – lungs stiff; actleticsis, difficult to get oxygen in because lung can’t expand to let in; pulmonary edema, puenothorax, cystic fibrousos
Lung Volumes and Capacities
lung function, which reflects the mechanics of ventilation, as viewed in terms of lung volumes and lung capacities. Lung volumes are categorized as tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume. Lung capacity is evaluated in terms of vital capacity inspiratory capacity, functional residual capacity in total lung capacity.
(decrease lung compliance, increase airway resistance)*; The right ventricle of the heart is affected ultimately by lung disease because it must pump blood through the lungs against greater resistance. Dyspnea may be associated with neurological or neuromuscular disorders that affect respiratory function. Dyspnea can also be after physical exercise in people without disease. It is also common. At the end of life in patients with a variety of disorders. In general, acute diseases of the lung, produce a more severe grade of dyspnea, then do chronic diseases. Sudden dyspnea and a healthy patient may indicate pneumothorax, acute respiratory obstruction, allergic reaction, or myocardial infarction. In immobilized patients, sudden dyspnea may denote pulmonary embolism. Dyspnea and tachypnea, accompanied by progressive hypoxemia in a person who has recently experienced lung trauma, shock, cardiopulmonary bypass, and multiple blood transfusions may signal acute respiratory distress syndrome
inability to breathe easily. Except in the upright position may be found in patients with heart disease, and occasionally in patients were COPD; dyspnea with an expiratory wheeze occurs with COPD. Noisy breathing may result from a narrowing of the airway or localized obstruction of a major bronchus by tumor or foreign body. The high-pitched sound heard usually on inspiration when someone is breathing through a partially blocked upper airways called stridor. The presence of both inspiratory and expiratory wheezing usually signifies asthma, if a person does not have heart failure. Because dyspnea can occur with other disorders. These disorders also need to be considered when obtain the patient’s health history.
cough is a reflex that protects the lungs from the accumulation of secretions or that inhalation of foreign bodies. Its presence or absence can be a diagnostic because some disorders cause coughing and others suppress it. The cough reflex may be impaired by week or paralyzed respiratory muscles, prolonging inactivity, the presence of a nasogastric tube, or depressed function of medullary centers in the brain. Cough results from irritation of the mucous membranes anywhere in the respiratory tract. The stimulus that produces a cough may arise from an infectious process or from an airborne irritants such as smoke, small, dusk, or a gas. A persistent infrequent cough can be exhausting and cause pain. Cough may indicate serious pulmonary diseases or a variety of other problems as well, including cardiac disease, medication reaction, smoking, acid reflux. To help determine the cause of the cough, the nurse describes the cough: dry, hacking, brassy, wheezing, lose, or severe. A dry, irritative cough is characteristic of an upper airway infection of viral origin, or it may be a side effect of ace inhibitor medication. And irritative, high pitched cough can be caused by laryngitis. A brassy cough is a result of tracheal lesion, while a severe or changing cough may indicate bronchial genic carcinoma. Pleuritic chest pain that accompanies coughing may indicate plural or chest wall involvement.
patient who coughs long enough almost invariably produces sputum*. Sputum production is a reaction to the lungs to and constant reoccurring irritant. It also may be associated with the nasal drainage. The nature of the sputum is often indicative of its cause. A profuse amount of purulent sputum (thick yellow, green, or rust colored) or a change in color of the sputum is a common sign of bacterial infection*. Thin, mucoid sputum frequently results from viral bronchitis. A gradual increases sputum over time may occur with chronic bronchitis. Pink tinge, mucoid sputum suggests a lung tumor. Profuse frothy pink material, often wells up into the throat may indicate pulmonary edema*. Foul-smelling sputum in bad breath points to the presence of lung abscess.
is a high-pitched, musical sound heard mainly on expiration (asthma) or inspiration (bronchitis). It is often the major finding in a patient with bronchial constriction or airway narrowing. Rhonchi are low pitch continuous sounds heard over the lungs in partial airway obstruction. Depending on their location and severity, the sounds may be heard with or without the stethoscope.
is a symptom of both pulmonary and cardiac disorders. The onset of hemoptysis is usually sudden, and it may be intermittent or continuous. Signs, which vary from bloodstained sputum to a large, sudden hemorrhage, always requires an investigation. The most common causes are: pulmonary infection, carcinoma of the lung, abnormalities of the heart or blood vessels, pulmonary artery or vein abnormalities, pulmonary embolism in infarction. Diagnostic evaluation to determine the cause include chest x-ray, chest angiographic, and bronchoscopy. A careful history and physical exam are necessary to identify the underlying disorder, irrespective of whether the bleeding involved a small amount of blood in the sputum or a massive hemorrhage. The amount of blood produced is not always proportional to the seriousness of the cost.
is the administration of oxygen and at a concentration greater than that found in any environment atmosphere. At sea level, the concentration of oxygen in room air is 21%. The goal of oxygen therapy is to provide adequate transport of oxygen in the blood, while decreasing the work of breathing and reducing stress on the myocardium. Oxygen transport to the tissue depends on factors such as cardiac output, arterial oxygen content, concentration of hemoglobin, and metabolic requirement. These factors must be kept in mind when oxygen therapy is considered.
indications of oxygen therapy
A change in the patient’s respiratory rate or pattern may be one of the earliest indicators of the need for oxygen therapy. These changes may result from hypoxemia or hypoxia
(Hypoxemia – low O2 in blood leads to hypoxia)* is a decrease in the arterial oxygen tension in the blood, it manifested by changes in mental status (progressing through impaired judgment, agitation, disorientation, confusion, lethargy, and coma), dyspnea, increase in blood pressure, changes in heart rate, dysrhythmias, central cyanosis (late sign), diaphoresis, and cold extremities
(Hypoxia – low blood in the tissues so s/s: blueness)* a decrease in oxygen supply to the tissues, which can also be cause by problems outside the respiratory system. Severe hypoxia can be life-threatening. The signs and symptoms signaling the need for oxygen may depend on how suddenly this need occurs. With rapidly developing hypoxia, changes occur in the central nervous system, because the higher neurological centers are very sensitive to oxygen deprivation. The clinical picture may resemble that of alcohol intoxication, with the patient exhibiting lack of coordination impaired judgment. With long-standing hypoxia (COPD) , fatigue, drowsiness, apathy, inattentiveness, and delayed reaction time may occur. The need for oxygen is assessed by arterial blood gas analysis, pulse ox, imagery, and clinical evaluation
complications of oxygen
oxygen is a medication, and except in an emergency situation it is administered only when prescribed by a physician. In general, patients with respiratory conditions are given oxygen therapy, only to increase arterial oxygen pressure back to the patient’s normal baseline, which may vary from 60 to 95 mm hg, the blood at these levels is 80% to 98% saturated with oxygen; higher fraction of inspired oxygen (FiO2) flow values add no further significant amounts of oxygen to the red blood cells or plasma. Instead of helping, increased amounts of oxygen may produce toxic effects on the lungs and central nervous system or may depressed ventilation. It is important to observe for subtle indicators of in adequate oxygenation when oxygen is administered by any method. Therefore, the nurse assesses the patient frequently for confusion, restlessness, progressing to lethargy, diaphoresis, pallor, tachypnea, tachycardia, and hypertension. Intermittent or continuous pulse ox imagery is used to monitor oxygen levels.
may occur when to higher concentration of oxygen (greater than 50%) is administered for an extended period (longer than 48 hours). It is caused by overproduction of oxygen free radicals, which are byproducts of cell metabolism. If oxygen toxicity is untreated, these radicals can severely damage or kill cells. Antioxidants such as vitamin E, vitamin C, and beta-carotene may help defend against oxygen free radicals. The dietitian can adjust the patient’s diet so that it is rich in antioxidants; supplements are also available for patients who have a decreased appetite, or who is unable to eat.
oxygen toxicity s/s
include substernal discomfort, paresthesia, dyspnea, restlessness, fatigue, malaise, progressive respiratory difficulty, factory hypoxemia, alveolar atelectasis, and alveolar infiltrates evident on x-ray. Prevention of oxygen toxicity is achieved by using oxygen only as prescribed. High concentrations of oxygen are necessary, is important to minimize the duration of administration and reduce the concentration as soon as possible.
suppression of ventilation
in many patients with COPD, the stimulus for respiration is a decrease in blood oxygen rather than an elevation of carbon dioxide levels. The administration of a high concentration of oxygen removes the respiratory drive that has been created largely by the patient’s chronic low oxygen tension. The resulting decrease in alveolar ventilation can cause a progressive increase in arterial carbon dioxide pressure (PaCO2). This hypoventilation can, in rare cases, lead to acute respiratory failure secondary to carbon dioxide narcosis, acidosis, and death. Oxygen-induced hypoventilation is prevented by administering oxygen at a low flow rate (1-2 L/Min) and by closely monitoring the respiratory rate and the oxygen saturation as measured by pulse oximetry.
Methods of Oxygen Administration
Many different oxygen devices are used, and all deliver oxygen if they are used as prescribed and maintained correctly. The amount of oxygen delivered is expressed as a percentage concentration (70%). The appropriate form of oxygen therapy is best determined by arterial blood gas levels, which indicate the patient’s oxygenation status. Oxygen delivery systems are classified as low flow or high flow delivery systems. Low flow systems contribute partially to the inspired gas the patient breeze, which means that the patient breath some room air along with the oxygen. These systems do not provide a constant or know concentration of inspired oxygen. The amount of inspired oxygen changes as the patient breathing changes. Examples of low flow systems include nasal cannula simple mass, partial rebreather, and non-rebreather mask. In contrast, high flow systems provide a total inspired air. A specific percentage of oxygen is delivered independently of the patient’s breathing. High flow systems are indicated for patients who require a constant the precise amount of oxygen. Examples of such systems include trans tracheal catheters, veni mask, aerosol mask, tracheostomy collars, T pieces, and face tents.
If giving O2 greather than 6 L then
have to humidify O2
is to use when the patient requires a low to medium concentration of oxygen for which precise accuracy is not essential. This method is relatively simple and allows the patient to move about in the bed, talk, cough, and eat without interrupting oxygen flow. Flow rates in excess of 6 to 8 L per minute may lead to swallowing of air or may cause irritation and drying of the nasal oropharyngeal mucosa. When oxygen is administered the percentage of oxygen reaching the lung varies with the depth and rate of respirations, particularly if the nasal mucosa is swollen or if the patient is a mouth breather. Low flow*
are used to administer low to moderate concentrations of oxygen. The body of the mask itself gathers and stores oxygen between breaths. The patient exhales directly through the opening of the ports on the body of the mask. If oxygen flow ceases, the patient can drawl air in through these openings around the mask edges. Although widely used these mass cannot be used for controlled oxygen concentration and must be at adjusted for proper fit. They should not press to tightly against the skin. Because this can cause a sense of claustrophobia, as well as skin breakdown; adjustable elastic bands are provided to ensure comfort and security. Low flow*
Partial- re-breathing mask-
have a reservoir bag that must remain inflated during both inspiration and expiration. The nurse adjusts the oxygen flow to ensure that the bag does not collapse during inhalation. A high concentration of oxygen can be delivered because both the mask in the bag, serve as reservoirs for oxygen. Oxygen enters the masks through small bore tubing that connects to the junction of the mask and bag as the patient inhales, gases drawn from the mass, from the bag, and potentially from room air through the exhalation Port. As the patient exhales, the first third of exhaled filling the reservoir bag. This is mainly dead space and is not participating gas exchange in the lungs. Therefore, it has a high concentration. The remainder of the exhaled gases vented through the exhaled ports. The actual percentage of oxygen delivered is influenced by the patient’s breathing patterns.
Nonrebreather can be partial nonreabreather by
taking white tabs off than 50% O2.
are similar in design to partial rebreathing mask, except that they have additional valves. A one-way valve located between the reservoir bag and the base of the mask allow gas from the reservoir back to enter the mask on inhalation but prevents gas in the mask from flowing back into the reservoir bag during exhalation. One-way valves located at the exhalation ports prevent room air from entering the mass during installation. They also allow the patient’s exhaled gas to exit the mask on exhalation. As with the partial rebreathing mask, it is important to adjust the oxygen flow so that the reservoir bag does not completely collapse on inhalation. In theory, if the non-rebreathing mask fits the patient snugly in both sides. The exhalation ports have one-way valves, it is possible the patient to receive 100% oxygen, making the non-rebreather mask a high flow oxygen system. However, because it is difficult to get an exact fit of the mask on every patient, and some non-rebreathing mask have only a one way exhalation valve, making it a low flow oxygen system. nonrebreather pt breathing in 100% O2*
is the most reliable and accurate method for delivering precise concentration of oxygen through noninvasive means. The mask is constructed in a way that allows a consistent flow of room air blended with a fixed flow of oxygen. It is used primarily for patients with COPD because it can accurately provide appropriate levels of supplemental oxygen, thus avoiding the risk of suppressing the hypoxic Drive.
high flow, used for COPD, allows to dial in how much oxygen. (COPD pt on continuous pulse ox); High flow O2 more than 48 can be dangerous to pt, will cause toxicity; So sooner get off O2 better for pt*