RESP PATHO Flashcards
- Describe dyspnea, orthopnea and paroxysmal nocturnal dyspnea (PND).
Discomfort in breathing (shortness of breath)
Signs include flaring of the nostrils, use of accessory muscles of respiration
Orthopnea: dyspnea upon lying down (causes abdominal contents to put pressure on diaphragm, plus redistribution of blood to the lungs)
PND: awaking at night with dyspnea
- Describe 7 other symptoms/signs of respiratory disease.
Cough – initiated by irritant receptors in the airway. There are few of thesis in the distal portions of the “respiratory tree”, so it is possible for significant secretions to build up before the cough reflex occurs
Abnormal sputum – changes in the amount, colour and consistency (microscopic observation can reveal cellular debris and microorganisms)
Hemoptysis: coughing up of blood (bright red, alkaline pH, frothy sputum)
Abnormal breathing pattern: hypo – or hyperventilation
Cyanosis: bluish discolouration of skin and mucous membranes, caused by increased amounts of deoxygenated hemoglobin in the blood
Clubbing: selective bulbous enlargement of the end of a digit
Pain: originates in pleurae, airways or chest wall. Caused by infection, inflammation, stiff muscles from coughing
- Define hypercapnia (hypercarbia), its immediate cause, and three occurrences that can bring the immediate cause to happen.
Increased carbon dioxide in the arterial blood
Caused by hypoventilation of the alveoli (CO2 passes very readily from the blood to the alveolar space (20x more readily than with O2, so is affected only by exchange in alveolar gases that occurs with ventilation))
Can be a result of anything decreasing drive/ability to breathe, including:
Drugs, diseases of the medulla, chest injuries
- Define hypoxemia and explain the difference from hypoxia.
Reduced oxygenation of arterial blood
Different from hypoxia, which is reduced oxygenation of tissues
- Explain the 3 mechanisms that can reduce oxygenation of the blood, including the following questions: a. By what two means can oxygen delivery to the alveoli be decreased? Be familiar with examples of conditions/diseases that can cause this. b. What does V/Q refer to? c. What is the most common cause of hypoxemia? d. Describe the conditions of low and high V/Q, and be familiar with examples of diseases that cause each. e. Be familiar with conditions that can decrease diffusion across the alveolocapillary membrane.
Hypoxemia results from defects in one or more of the 3 mechanisms of oxygenation: oxygen delivery to the alveoli, diffusion of oxygen from the alveoli into the blood, and anatomical right to left shunting
Oxygen delivery to the alveoli: decreased oxygen in the air/decreased ventilation (a problem with unconscious individuals, those with disease that restricts chest expansion, COPD) & decreased diffusion across the alveolocapillary membrane (due to thickened membrane brought about through edema, or fibrosis)
V: alveolar ventilation & Q: perfusion (the amount of blood perfusing the alveolar capillaries
A mismatch of the V/Q ratio
High V/Q: inadequate perfusion of well-ventilated area, producing alveolar dead space (wasted ventilation) most common cause is pulmonary embolism & low V/Q: inadequate ventilation of well-perfused area of lung (atelectasis, asthma, pulmonary edema)
- What is the result of, and what causes chest wall restriction? Describe flail chest.
Results in a decrease in tidal volume
Occurs when the chest wall is deformed, traumatized, immobilized or heavy from the accumulation of fat (grossly obese, neuromuscular disease)
- Define pneumothorax and its effect on the lung.
Presence of air in the pleural space caused by a rupture in the visceral or parietal pleura
Negative pressure of pleural cavity is destroyed and lung tends to recoil and collapse towards hilum
- What is tension pneumothorax, and how does it develop?
Preventing air from escaping the pleural cavity with exhalation
Develops when a lung or chest wall injury is such that it allows air into the pleural space but not out of it (one-way valve)
- Define pleural effusion and how it usually occurs.
Presence of excess fluid in the pleural space
Usually through migration of fluid through walls of capillaries bordering the pleura
- Define empyema and how it can occur.
Infected pleural effusion
Complication of pneumonia, surgery
- Describe atelectasis, its causes and manifestations.
Collapse of lung tissue
External compression (e.g. fluid in pleural space, tumor, abdominal distention), obstructed airways (air is absorbed form obstructed alveoli and they collapse), inhalation of concentrated oxygen (increases rate of absorption of gases, leading to collapse), decreased production of surfactant
Dyspnea and cough
- What medical procedure often results in atelectasis and what measures can be taken to improve patients’ condition?
Tends to develop after surgery (patients that are in pain breathe shallowly. Viscous secretions can result from anaesthesia)
Post-surgery patients are advised to breathe deeply, become ambulatory asap, and change positions frequently when lying down to prevent the thick bronchial secretions produced by narcotics and anaesthesia from obstructing an airway
- Describe bronchiectasis and be familiar with some causes.
Permanent dilation of the bronchi (secondary to other diseases that cause chronic inflammation of bronchial wall)
Chronic inflammation leads to destruction of elastic and muscular components of bronchi walls and permanent dilation
- Describe the pathophysiology behind cystic fibrosis and its treatment.
Mutation produces inability of cell membranes to transport chloride ion. This causes a series of events, resulting in increased absorbance of sodium and water from respiratory secretions. This produces very thick mucous, which is difficult for cilia to move. The mucous then accumulates, increasing the risk of infections
Includes antibiotics to control infections, possible replacement of pancreatic enzymes
- What is a pulmonary embolism, and of what is the most common embolus comprised?
Occlusion of a portion of the pulmonary vascular bed by an embolus
Is a clot from deep venous thrombosis involving the lower leg
- What does obstruction of blood flow cause in the lung?
Obstruction of blood flow causes pulmonary vessels to constrict, resulting in impaired gas exchange (V/Q mismatch) and hypoxemia.
- What is the result if the clot is not dissolved soon enough?
If clot is not dissolved rapidly, the resulting hypertension could possibly lead to right heart failure
- What are the clinical manifestations of a pulmonary embolism?
Depends upon size and location of obstruction
Small emboli may go unnoticed unless patient’s health is otherwise compromised
Moderate emboli: sudden onset chest pain, dyspnea, tachypnea, tachycardia
Massive emboli: sudden collapse, crushing chest pain, shock – often fatal
- Define pulmonary hypertension, and explain how hypoxemia and certain heart conditions can lead to this condition.
Elevated mean pulmonary artery pressure
Most cases develop as a serious complication of many acute and chronic pulmonary disorders, a common cause is continued exposure of pulmonary vessels to hypoxemia, which causes these vessels to constrict (unlike systemic vessels, which dilate)
Can also be caused by mitral valve disorders or left ventricular diastolic dysfunction, which raise left atrial pressure
- What is cor pulmonale, its primary cause and its effects?
Right heart failure brought about through lung disease or chronic pulmonary hypertension
Increased work of the right ventricle causes hypertrophy and eventual failure
Results in systemic venous congestion, peripheral edema, fatigue
- What is pulmonary edema, and describe how this is commonly caused.
Excess fluid in the lungs
Most common cause is left-sided heart failure. Failure of left ventricle causes increased filling pressure, which causes back-up of blood in lungs, increasing pressure in lung capillaries. When this exceeds osmotic pressure of lung capillaries, fluid & RBCs leave capillaries and collect in the interstitial space
- Why does pulmonary edema result in hypoxemia?
When there is too much interstitial fluid for lymph system to collect, edema occurs. Fluid eventually leaks into the alveoli: fewer alveoli available to expand with air, means a reduction in surface area of respiratory membrane, thickening of available respiratory membrane (increased distance for oxygen molecules to diffuse) -> results in reduced oxygen diffusion rate
- Describe clinical manifestations of pulmonary edema.
Dyspnea, cyanosis, increased physical effort in breathing, blood tinged frothy sputum