Respiratory 4

oelomar's version from 2016-04-20 15:14


Question Answer
What is a pneumothorax?Air in the pleural space that causes an uncoupling of the lung from the chest wall.
What is the difference between a primary (spontaneous) and a secondary pneumothorax?A primary pneumothorax is one that occurs spontaneously without an apparent cause and in the absence of significant lung disease, whereas a secondary pneumothorax occurs in the presence of existing lung pathology.
What is a traumatic pneumothorax?A pneumothorax caused by physical trauma to the chest, or as a complication of medical or surgical intervention.
In which group of patients do spontaneous pneumothoraces most commonly occur?Young males, the male-to-female ratio being 6:1. These males are often tall and thin.
What are the clinical features of a pneumothorax?Sudden onset pleuritic pain localised to the affected side and breathlessness.
How is a pneumothorax diagnosed?The combination of absent breath sounds and resonant percussion is diagnostic of pneumothorax. An x-ray illustrates the collapse of the lung as extra black space.
How is a primary pneumothorax treated?Treated with needle aspirations (2nd intercostal space at the midclavicular line) if patient is short of breath or rim of air is >2cm on x-ray; otherwise discharge.
How is a secondary pneumothorax treated?If patient is short of breath, >50 years old, and the rim of air is >2cm on an X-ray then a chest drain is required. Otherwise aspiration should be attempted if the rim of air is between 1-2cm. If the pneumothorax is less the 1cm then give oxygen and admit for 24 hours. The chest drain is inserted in the 4th-6th intercostal space in the midaxillary line, connected to a Heimlich valve.
What is a Heimlich valve?A one-way valve used with a chest tube to stop air from coming into your chest through the tube when you breathe in.
What is a tension pneumothorax?A pneumothorax (primary spontaneous, secondary spontaneous, or traumatic) that leads to significant impairment of respiration and/or blood circulation. Trapped air accumulates in the pleural space and the intrapleural pressure rises. The pressure causes mediastinal displacement towards the opposite side, with compression of the opposite normal lung and impairment of systemic venous return.
What are the clinical features of a tension pneumothorax?Tension pneumothorax causes severe breathlessness, cyanosis, tachycardia, hypotension, grossly elevated jugular venous pulse, and evidence of mediastinal shift (trachea and apex displaced away from the side of the chest under tension, which may appear unduly prominent).
How is a tension pneumothorax treated?In a suspected tension pneumothorax treat the patient, do not wait to confirm diagnosis with chest x-ray. Insert large-bore needle with a syringe, partially filled with 0.9% saline into the 2nd intercostal space at the midclavicular line. Remove plunger to allow the trapped air to bubble through the syringe until a chest tube can be placed.


Question Answer
What is pleural effusion?Excess fluid that accumulates in the pleural cavity which can therefore impair breathing by limiting the expansion of the lungs.
What is an exudate?Any fluid that filters from the circulatory system into lesions or areas of inflammation.
What is a transudate?Extravascular fluid with low protein content and a low specific gravity.
What is the difference between an exudate and a transudate?A transudate has a lower protein content and a lower specific gravity. Other differences include that the main causes of a transudate are an increase in hydrostatic pressure and a decrease in colloid osmotic pressure, whereas in an exudate the main cause is due to inflammation.
What test can be used to distinguish between an exudate and a transudate, and how is it carried out and interpreted?The Rivalta test. A test tube is filled with distilled water and acetic acid is added. To this mixture one drop of the effusion to be tested is added. If the drop dissipates, the test is negative, indicating a transudate. If the drop precipitates, the test is positive, indicating an exudate.
Name some causes of exudate pleural effusions.Pneumonia, malignancy, TB, trauma, sarcoidosis.
Name some causes of transudate pleural effusions.CHF, nephrotic syndrome, hepatic cirrhosis.
How is a pleural effusion diagnosed?Thoracocentesis with ultrasound guidance if the effusion is small.
What are the clinical features of a pleural effusion?Can be asymptomatic or present with dyspnoea and pleuritic chest pain. There is also decreased chest expansion and a stony dull percussion note. Diminished breath sounds occur on the affected side.
What is pleurodesis?A medical procedure performed to prevent the recurrence of pneumothorax or recurrent pleural effusion. The pleural space is artificially obliterated. It involves the adhesion of the two pleurae.
What is the “Light’s criteria”?Criteria for distinguishing between exudative and transudative pleural effusions. An exudate is likely if at least one of the following criteria are met: pleural fluid protein:serum protein ratio > 0.5; pleural fluid LDH: serum LDH ratio > 0.6; pleural fluid LDH > two-thirds of the upper limit of normal serum LDH.


Question Answer
What is peak expiratory flow rate?A test that measures how quickly a person can exhale.
What are the normal values of FEV1 and FVC?4L and 5L respectively (or the normal ratio is 80%).
What is the nitric oxide exhalation test used for?Exhaled nitric oxide can be measured in a breath test for asthma or other conditions characterised by airway inflammation. It is an indicator of airway inflammation, and can be increased in asthma.
What does yellow/green coloured sputum suggest?It indicates neutrophils, therefore suggesting bacterial colonisation or infection.
What does the presence of blood in the sputum suggest?Neoplasm or pulmonary infarct.
What does serous/frothy/pink sputum suggest?Pulmonary oedema.
What does foamy/white sputum suggest?May come from obstruction or even oedema.
What does rusty-coloured sputum suggest?Pneumococcal bacteria.


Question Answer
What is acute respiratory distress syndrome (ARDS)?A medical condition characterised by widespread inflammation in the lungs. The hallmark of ARDS is diffuse injury to cells which form the alveolar barrier, surfactant dysfunction, activation of the innate immune response, and abnormal coagulation. In effect, ARDS results in impaired gas exchange within the lungs at the level of the microscopic alveoli. It occurs in critically ill patients, and is associated with a high mortality rate (20-50%).
What are the most common causes of ARDS?Pneumonia, aspiration of gastric contents, sepsis, severe trauma with shock and multiple transfusions.
What are the clinical features of ARDS?The first sign is often an unexplained tachypnoea, followed by increasing hypoxaemia, with central cyanosis, and breathlessness. Fine crackles are heard throughout both lung fields. Later, the chest X-ray shows bilateral diffuse shadowing, interstitial at first, but subsequently with an alveolar pattern and air bronchograms that may then progress to the picture of complete “white-out”.
How is ARDS managed?This is based on treatment of the underlying condition (e.g. eradication of sepsis), supportive measures, and avoidance of complications such as ventilator-associated pneumonia. ARDS is usually treated with mechanical ventilation in the intensive care unit, usually through oro-tracheal intubation or tracheostomy whenever prolonged ventilation (2 weeks or more) is necessary.

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