Ch - 23 Disorders of ventilation and gas exchange Flashcards
What is hypoxemia? Hypercapnia?
Refers to the reduction in the PO2 of the arterial blood. It can result from an inadequate amount of O2 in the air, disease of the respiratory system, dysfunction of the neurologic system or alterations in circulatory function or the neurologic system, or alterations in circulatory function. The mechanisms whereby respiratory disorders lead to a significant reduction in PO2 are hypoventilation, impaired diffusion of gases, inadequate circulation of blood through the pulmonary capillaries, and mismatching of ventilation and perfusion. Pronounced hypoxemia may produce personality changes, restlessness, uncoordinated muscle movements, euphoria, impaired judgement, delirium and eventually stupor and coma.
Diagnosis is clinical observations, diagnostic tests that measure PO2 levels. Blood gases. pulse oximetry
Treatment - oxygen by NP or mask or endotracheal tube. Highflow can be used as well as low flow. But can oxygen toxicity can lead to lung injury.
Hypercapnia - Refers to an increase in the carbon dioxide content of the arterial blood. PCO2 and inversely related to alveolar ventilation. Affects a number of body functions, including acid base balance, kidney, nervous system and cardiovascular function. PCO2 increase usually the body compensates increasing HCO3 renal bicarbonate retention, which results in an inc in serum HCO3 and pH levels.
Treatment - Respiratory muscle retraining aimed at improving the PCO2. Mechanical ventilation may be needed.
Pleuritis? Pleural effusion?
Pleuritis refers to inflammation of the parietal pleura that typically results in characteristic pleural pain. Pain is usually unilateral and abrupt in onset and is usually made worse by chest movement such as deep breathing and coughing that exaggerate pressure changes in the pleural cavity and inc movement of the inflamed or injured pleural surfaces. Usually caused by viral infections or pneumonia.
Treatment - Analgesics and nonsteroidal anti inflammatory drugs’ NSAIDs
Pleural effusion refers to an abnormal collection of fluid in the pleural cavity. Normally, fluid enters the pleural space from capillaries in the parietal pleura and is removed by their lymphatics. It may accumulate when there is excess fluid or dec removal by the lymphatics. The fluid maybe transudate or exudate, purulent, chyle or sanguineous. Clear is a hydrothorax is caused by heart failure. Exudate often contains inflammatory cells.
Empyema refers to an infections in the pleural cavity that results in exudate containing glucose, proteins, leukocytes and debris from dead cells and tissue.
Chylothorax is the effusion of lymph in the thoracic cavity. Chyle a milky fluid containing chylomicrons is found in lymph fluid drained by lacteals in the villi in the small intestine. Caused by trauma, inflammation or malignant infiltration
Hemothorax - is blood. May come from chest injury, a complication of chest surgery, malignancies or rupture of a great vessel like aortic aneurysm.
Mani- dullness to percussion and diminished breath sounds. Hypoxemia may occur because of dec surface area. Dyspnea, most common. when fluid compressed the lung resulting in inc effort or rate of breathing.
Diagnosis and treatment - chest xray, CT, thoracentesis for sample. Chest tube or draining of the fluid
Pneumothorax?
Refers to the presence of air in the pleural space. Causes partial or complete collapse of the affected lung. Can occur without an obvious cause or injury.
Spontaneous - is hypothesized to occur due to the rupture of an air filled bleb, or blister on the surface of the lung. Because alveolar pressure normally is greater than pleural pressure, air flows from the alveoli into the pleural space, causing the involved portion of the lung to collapse as a result of its own recoil. Smoking may be a cause, or a pt who is tall and thin. Secondary is more severe because they already have a lung disease.
Traumatic - caused by penetrating or nonpenetrating chest injuries, usually fractured or dislocated ribs that penetrate the pleura. Some medical procedures could cause it.
Tension - occurs when the intrapleural pressure exceeds atmospheric pressure. A life threatening condition occurs when injury to the chest or respiratory structures allows air to enter but not leave the pleural space
Clinical - it depends on size and integrity of the underlying lung. An immediate inc in respiratory rate, accompanied by dyspnea. Lung sounds are dec or absent over the area. May cause distention of the neck veins, subcutaneous emphysema and shock. Hypoxemia immediately after.
Diagnosis and Treatment - chest xray, CT, US. Blood gas and pulse oximetry. Treatment - oxygen and air can be removed by needle aspiration or closed drainage system. Sucking chest wounds, should be treated by promptly covering the area with an airtight covering. Chest tubes are inserted as soon as possible
Atelectasis?
Refers to an incomplete expansion of a lung or portion of a lung. Caused by airway obstruction, lung compression or inc recoil of the lung due to loss of pulmonary surfactant. Primary is a newborn that the lung has never been inflated. Adults is usually an airway obstruction, mucus plug or by external compression of the airway from fluid. can inc after surgery.
Mani - tachypnea, tachycardia, dyspnea, cyanosis, signs of hypoxemia, diminished chest expansion, absence of breath sounds, and intercostal retraction. signs of respiratory distress
Diagnosis and treatment - chest xray, CT
Treatment - reducing airway obstruction or lung compression and at reinflation of the collapsed area of the lung. Ambulation, deep breathing and body positions that favor inc lung expansion are used when appropriate. Oxygen maybe needed.
Obstructive airway disorders? Asthma?
Are caused by conditions that limit expiratory airflow. Bronchial asthma represents an acute and reversible form of airway disease, COPD, bronchiectasis, CF.
The contraction and relaxation of the smooth muscle layer, which is innervated by the ANS controls the diameter of the bronchial airways and consequent resistance to airflow. Parasympathetic stimulation through the vagus nerve and cholinergic receptors produces bronchoconstriction, whereas sympathetic stimulation, through B2 adrenergic receptors, produces bronchodilation. The inflammatory mediators, such as histamine act directly on bronchial smooth muscle cells to produce bronchoconstriction.
Bronchial asthma - affects adults and children and occurs in all populations and locations throughout the world. It is a chronic inflammatory disease of the airways involving recurring symptoms of airflow obstruction and bronchial hyper responsiveness. By episodic wheezing, difficulty breathing, feeling of chest tightness, and cough.
Atopic - is typically initiated by a type I hypersensitivity reaction induced by exposure to an extrinsic antigen or allergen. Like hay fever, urticaria, and eczema. Airborne allergens. Early phase response 10-20 mins. late phase response - 4-8 hours after exposure
Nonatopic asthma - triggers from respiratory tract infections, exercise, hyperventilation, cold air, drugs and chemicals, hormonal changes and emotional upsets, airborne pollutants and gastroesophageal reflux.
Mani - from episodes of wheezing and feeling of chest tightness to acute immobilizing attacks. During an asthma attack the airways narrow because of bronchospasm, edema of the bronchial mucosa and mucus plugging. Air trapped produces an inc in residual volume along with a dec in inspiratory reserve capacity and forced vital capacity. Depends on the severity.
Diagnosis and treatment - history and examination.
Quick relief medications - Short acting B2 agonists, anticholinergic agents and systemic corticosteroids. Usually by inhalation.
Long term - is taken on a daily basis to achieve and maintain control of persistent asthma symptoms. Inhaled corticosteroids, longacting bronchodilators, chromoly and nedocromil, leukotriene receptor antagonists and theophylline.
COPD? Emphysema? Chronic Bronchitis?
Denotes a group of respiratory disorders characterized by chronic and recurrent obstruction of airflow in the pulmonary airways. Most common cause is smoking.
- Emphysema - by a loss of lung elasticity and abnormal enlargement of the air spaces distal to the terminal bronchioles, with destruction of the alveolar walls and capillary beds. 2 types - centriacinar or centrilobular and panacinar
- Chronic bronchitis - represents airway obstruction of the major and small airways. Earliest feature is hypersecretion of mucus in the large airways. Viral and bacterial infections are common in persons with chronic bronchitis.
Mani - have a insidious onset and persons seek medical attention in the fifth and sixth decade of life. excessive cough, sputum production, and shortness of breath. Productive cough in morning and dyspnea more severe as the disease progresses.
Diagnosis and treatment - history and physical exam, pulmonary function tests, chest xrays, and lab tests. Respiratory infections could be life threatening in pt with severe COPD. Oxygen therapy continuous low flow, using portable oxygen
Bronchiectasis?
is characterized by a permanent dilation of bronchi caused by destruction of the bronchial muscle wall and elastic supporting tissue. It occurs secondary to a number of abnormalities that profoundly obstruct the airways, or produce persistent infection, including atelectasis, obstruction of the smaller airways, diffuse bronchitis, an CF. TB was commonly associated.
Mani - by a chronic productive cough, often with several hundred milliliters of foulsmelling, purulent sputum a day. Hemoptysis is common. Dyspnea and wheezing occur in about 76% of pt. Weight loss, anemia, and other systemic mani are common in severe disease. Hypoxemia is seen in moderate to severe cases.
Diagnosis and treatment - history and imaging studies. Chest xray or CT. Early management of infections along with regular postural drainage and chest physical therapy.
Cystic Fibrosis CF?
Major cause of severe chronic respiratory disease in children and young adults, is an inherited disorder involving fluid secretion by the exocrine glands in the epithelial lining of the respiratory, gastrointestinal, and reproductive tracts. Is manifested by pancreatic exocrine deficiency and elevation of sodium chloride in the sweat. Nasal polyps, sinus infections, pancreatitis, and cholelithiasis are common. Is an inherited as an autosomal recessive trait. CF is caused by mutations in a single gene on the long arm of chromosome 7 that encodes for the CF transmembrane regulator, which functions as a chloride channel in epithelial cell membranes. Are relatively impermeable to the chloride ion.
Mani - of CF are caused by an accumulation of viscid mucus in the bronchi, impaired mucociliary clearance, and lung infections. Leads eventually to bronchiectasis.
Diagnosis and Treatment - Early diagnosis and treatment are important in delaying the onset and severity of chronic illness in children with CF. Presence of respiratory and gastrointestinal manifestations typical of CF, a history of CF in a sibling, or a positive newborn screening test. Chest physical therapy and mucolytic agents to prevent airway obstruction, and nutritional therapy including pancreatic enzyme replacement. 90% of pt with CF have complete loss of exocrine pancreatic function and inadequate digestion of fats and proteins. Require supplemental vitamins and minerals and enteric coated pH sensitive pancreatic enzyme supplements. Today pt can live into their 40s and beyond. Transplantation for end stage disease.
Interstitial lung dieseases?
Diffuse parenchymal lung diseases are a diverse group of lung disorders that produce similar inflammatory and fibrotic changes in the interstitium or interalveolar septa of the lung. May be acute or insidious, rapid or slow or static. Over a 100 see chart 23-1. Thought that these disorders are initiated by some type of injury to the alveolar epithelium, followed by an inflammatory process that involves the alveoli and interstitium of the lung.
Clinical - the interstitial lung diseases are characterized by clinical changes consistent with restrictive rather than obstructive changes in the lung. Have dyspnea, tachypnea, eventual cyanosis, without evidence of wheezing or signs of airway obstruction. Chest xrays to follow disease progress.
Idiopathic pulmonary fibrosis - in severe cases results in severe hypoxemia and cyanosis. Smoking inc risk. by patchy interstitial fibrosis that causes collapse of alveolar walls and formation of cystic spaces lined by hyperplastic type II alveolar cells or bronchial epithelium. Diagnosis is confirmed by surgical biopsy. Mean survival is 3-5 years.
Sarcoidosis - is a multisystem disorder in which granulomas are found in many tissues and organs, particularly the lung. Affects adults younger the 40 years of age although can happen in older. Diagnosis on an incidental chest film or because of insidious onset respiratory symptoms or constitutional signs and symptoms. By either progressive chronicity or periods of activity interspersed with remissions, sometimes permanent that may be spontaneous or induced by corticosteroid therapy.
Treatment - corticosteroid drugs are used,
Disorders of the Pulmonary circulation?
Pulomonary embolism - develops when a blood-borne substance lodges in a branch of pulmonary artery and obstructs blood flow. May consist of a thrombus, air that has accidentally been injected during IV, fat that has been mobilized from the bone marrow after a fracture or from a traumatized fat depot, or amniotic fluid that has entered the maternal circulation during childbirth.
Mani - Moderate emboli often present with breathlessness accompanied by pleuritic pain, apprehension, slight fever, and cough productive of blood streaked sputum. Tachycardia often occurs to compensate for dec oxygenation, and the breathing pattern is rapid and shallow. Massive present with sudden collapse, crushing substernal chest pain, shock, and sometimes loss of consciousness. Pulse is rapid and weak, BP is low skin is cyanotic and diaphoretic. Often are fatal.
Diagnosis and treatment - CT d dimer testing, lung perfusion scans, pulmonary angiography. Blood gas and clinical signs . Lab studies and xrays. Thrombolytic therapy using streptokinase, urokinase, or recombinant tissue plasminogen activator may be indicated in person with life threatening pulmonary emboli. Followed by anticoagulant therapy to prevent clot reoccurrence but carries the risk of bleeding complications and is contraindicated in post surgical. With unfractionated or low molecular weight heparin is given IV . Surgical interruption may be needed.
Pulmonary Hypertension? Secondary and Primary?
Is a disorder characterized by an abnormal elevation of pressure within the pulmonary circulation - the pulmonary arterial system. Once present is self perpetuating.
Secondary - refers to an inc in pulmonary pressures associated with other disease condition, Often the COPD, heart failure, sleep apnea, contributes. 1. elevation of pulmonary venous pressure. 2. inc pulmonary blood flow 3. pulmonary vascular obstruction and 4 hypoxemia.
Diagnosis xrays echocardiography, US Vasodilator therapy may be indicated.
Primary - PAH is persistent elevation in pulmonary artery pressure that occurs in the absence of identified cardiopulmonary or other secondary causes of pulmonary hypertension. It is a rare debilitating disorder
Treatment - prostacyclin analogues, endothelin receptor antagonist and phosphodiesterase type 5 inhibitors. Continuous longterm infusion of prostacylcin, a potent pulmonary vasodilator. IV through an indwelling catheter. Oral endothelin antagonists. Lung transplantation.
Cor Pulmonale - refers to right heart failure resulting from primary lung disease or pulmonary hypertension.
Signs of primary lung disease and the signs of right sided heart failure
Acute lung injury/Acute respiratory Distress syndrome ACL/ARDS
By severe dyspnea of rapid onset, hypoxemia, and pulmonary infiltrates. Aspiration of gastric contents, major trauma, sepsis, acute pancreatitis, hematologic disorders, metabolic events and reaction to drugs and toxins. Diffuse alveolar cell damage leads to accumulation of fluid, surfactant inactivation and formation of a hyaline membrane that is fibrous and impervious to gas exchange. As it progressed, the work of breathing becomes greatly inc as the lung stiffens and becomes more difficult to inflate, Inc intrapulmonary shunting of blood, impaired gas exchange and hypoxemia despite high oxygen therapy.
Clinical - is rapid onset 12-18 hours of initiating event of respiratory distress, an inc in respiratory rate, signs of respiratory failure. Chest xray shows diffuse bilateral infiltrates of the lung tissue in absence of cardiac dysfunction. Results in multiple organ failure,
Acute respiratory failure?
Can be viewed as impaired gas exchange due to either pump or lung failure or both. Can occur in the course of a number of conditions that impair ventilation, compromise the matching of ventilation and perfusion, or impair gas diffusion. ARF is a condition in which the respiratory system fails in one or both of its gas exchange functions - oxygenation of mixed venous blood and removal of carbon dioxide.
two types
- Hypoxemic respiratory failure - mismatching ventilation and perfusion - occurs when areas of the lung are ventilated but not perfused or when areas are perfused by not ventilated. In person with COPD by retention of CO2
- Impaired diffusion - describes a condition in which gas exchange between the alveolar air and pulmonary blood is impeded because of an inc in the distance for diffusion or a dec in the permability or surface area of the respiratory membranes to the movement of gases. Commonly in interstitial lung disease, ALI/ARDS pulmonary edema, and pneumonia.
Hypercapnic/Hypoxemia Respiratory failure - Pt are unable to maintain a level of alveolar ventilation sufficient to eliminate CO2 and keep arterial O2 levels within normal range. Occurs when the volume of fresh air moving into and out of the lung is significantly reduced. Caused by conditions outside the lung depression of the respiratory center, diseases of the nerves supplying the respiratory muscles, disorders of the respiratory muscles, exacerbation of chronic lung disease or thoracic cage disorders.
Clinical - by varying degrees of hypoxemia and hypercapnia.
Treatment - establishment of an airway, use of bronchodilating drugs, and antibiotics for respiratory infections. Controlled oxygen therapy and mechanical ventilation are used in treating blood gas abnormalities. Mechanical ventilation may be lifesaving.
