key: cord-0036811-mr7zy63e
authors: Banerjee, Ashis
title: Respiratory Emergencies
date: 2017-03-16
journal: Emergency Clinical Diagnosis
DOI: 10.1007/978-3-319-50718-7_2
sha: db4365e8f62db4e2d11f2168d0c3e6cc83e5b82a
doc_id: 36811
cord_uid: mr7zy63e

Causes of cough: Acute cough (<3 weeks): Respiratory tract infections: viral upper respiratory tract infection, viral rhinosinusitis, common cold, acute bacterial sinusitis, acute bronchitis, pneumonia, acute exacerbation of COPD; pertussis. Inhalation of direct irritants: dust, smoke, ozone, air pollutants. Inhalation of specific allergen in the asthmatic: pollen, or low concentration of non-specific irritants: cigarette smoke, perfume; house dust mites. Allergic rhinitis. Chemical exposure: chloramines in swimming pools. Medication: ACE inhibitors. Subacute cough (3–8 weeks): Post-infectious cough: prior viral upper respiratory tract infection. Bordetella pertussis infection. Subacute bacterial sinusitis. Asthma. Neoplasm. Chronic cough (>8 weeks): Persistent airway inflammation: COPD, asthma, bronchiectasis. Smoking. Neoplasm. Interstitial lung disease: pulmonary fibrosis. Persistent infection: tuberculosis; bronchiectasis. Raised left atrial pressure: mitral stenosis, left ventricular failure. Inhaled foreign body. Iatrogenic: ACE inhibitors, radiation pneumonitis, steroid aerosols. Aspiration syndrome: gastro-oesophageal reflux disease; bulbar dysfunction; oesophageal dysmotility. Psychogenic. Post-nasal drip syndrome (posterior nasal discharge and night cough): sinusitis; rhinitis (allergic; non-allergic; vasomotor). Primary ciliary dyskinesia.

Dyspnoea is the conscious and unpleasant awareness of increased work done during breathing, and may indicate cardiac, pulmonary, cardiopulmonary or neuromuscular disease. Dypsnoea is not synonymous with respiratory distress. There are a number of underlying mechanisms, which may coexist in the same patient.

• Physiological: exercise; high altitude • Pathological: anaemia; increased metabolism (fever, thyrotoxicosis) Impaired performance • Airflow obstruction: upper airway obstruction; obstructive lung disease: asthma, COPD, bronchiectasis; lower airway obstruction: foreign body • Reduced lung volume (restrictive lung disease): pleural disease/effusion; pneumothorax; kyphoscoliosis; massive obesity; spine or chest wall deformities; interstitial lung disease • Impaired gas exchange: alveolar lung disease: consolidation (pneumonia); pulmonary oedema • Loss of lung compliance: interstitial lung disease • Neuro-muscular diseases: Guillain-Barre syndrome; myasthenia gravis; diaphragmatic paralysis; poliomyelitis; spinal cord injury (cervical cord transection); muscular dystrophies • Loss of thoracic cage (chest wall) compliance

Hyperventilation resulting from medullary respiratory centre stimulation in response to chemical or neural stimuli

Increased arterial hydrogen ion concentration, e.g. metabolic acidosis producing air hunger (Kussmaul's breathing) Increased arterial paCO 2 , e.g. respiratory acidosis Decreased arterial PaO 2 via aortic, carotid and brain stem chemoreceptors, e.g. pneumonia, impaired oxygen delivery due to anaemia, shock and stroke Increased central arousal, e.g. exertion, anxiety, thyrotoxicosis, phaeochromocytoma Pulmonary J receptor discharge, e.g. pulmonary oedema

• Fine end-inspiratory crackles over both lung bases: pulmonary oedema • Medium end-inspiratory crackles: pulmonary fibrosis Causes of elevated D-dimer (plasma levels of the degradation product of cross-linked fibrin formed after fibrin lysis by plasmin)

The negative predictive value of D-dimer testing is high, while the positive predictive value is low. A negative D-dimer test measured using a high-sensitivity assay excludes pulmonary embolism when the pre-test probability is low. Causes for an elevated D-dimer include 

Asymmetrical, diffuse, hazy opacity that increases in density within the hemithorax in a cephalo-caudad direction, due to layering of the effusion posteriorly

The hemidiaphragm is obscured and the lateral costophrenic angle is blunted Opacity over lung apex with a concave interface inferiorly (pleural cap): the apex is the most dependent portion of the thorax tangential to the frontal x-ray beam Absence of air bronchograms and visualization of lung vessels through the density confirms that the increased opacity is extraparenchymal in location

A pleural effusion appears as an anechoic or hypoechoic zone between the parietal and visceral pleura. The lung sliding sign is absent. A transudate is echo-free. An exudate appears as an echoic collection, with floating echogenic debris, with or without pleural thickening and loculation. Empyema and haemothorax appear homogenous and echoic. The presence of floating fragments within a pleural effusion has been referred to as the plankton sign.

• Elliptical or oval pleural-based opacities without air bronchograms • Located along the course of a fissure or between the visceral and parietal pleura when the pleural layers are partly adherent • Does not shift freely within the pleural space with changing patient position • Rapid disappearance with diuresis has led to the term vanishing lung tumour

• Bases: blunting of costophrenic angle, with tenting of diaphragmatic pleura • Apices: apical pleural cap-curvilinear density at lung apex 

• Cervical trachea injury: hoarseness; stridor; haemoptysis; cervical subcutaneous emphysema • Intra-thoracic tracheo-bronchial injury: massive subcutaneous emphysema, unilateral or bilateral pneumothorax/haemothorax, pneumomediastinum, mediastinal haematoma, peribronchial air and partial pulmonary atelectasis; fallen lung sign caused by atelectatic lung falling infero-laterally from the hilum in the lower medial pleural space; failure of reexpansion of the lung after chest tube placement, related to massive air leak from bronchopleural fistula; abnormal migration of tip of endotracheal tube; tension pneumothorax with positive pressure ventilation 

• The commonest injury following blunt chest wall trauma in children • Caused by alveolar capillary disruption, leading to alveolar haemorrhage and interstitial oedema • Focal or multi-focal consolidation, crossing fissures and lobes, with sub-pleural sparing (1-2 mm region of non-opaque sub-pleural lung separating the area of consolidation from the adjacent chest wall) • Chest x-ray signs may take 4-6 h to develop and progress over 24-48 h; resolution within 3-5 days usually

The clinical features of rib fracture include:

• Pleuritic chest pain • Point tenderness • Production of pain by anteroposterior or lateral chest wall compression ("springing") • Local crepitus • Subcutaneous emphysema • 1st and 2nd rib fractures may be associated with vascular injury (aorta, subclavian artery) or brachial plexus injury • 11th and 12th rib fractures may be associated with visceral injury (liver, spleen, kidneys)

• Caused by direct trauma, such as anteroposterior compression from seat belt or steering wheel injuries, with posterior displacement of the distal sternal fragment, or indirect trauma, such as hyperflexion and axial compression, with posterior displacement of the proximal sternal agent. Manubrio-sternal joint dislocation may also result by these mechanisms. • Can be associated with myocardial or pulmonary contusion • Usually diagnosed on a lateral view of the sternum • Isolated sternal fracture with normal 12 lead ECG and normal chest x-ray carries a very low risk of intrathoracic injury 

Inflammatory: granuloma; lung abscess; rheumatoid nodule

arteriovenous malformation; lung cyst; broncho-pulmonary sequestration; bronchial atresia with mucoid impaction • Miscellaneous: pulmonary infarct; intrapulmonary lymph node; mucoid impaction; haematoma; amyloidosis; normal confluence of pulmonary veins; pseudotumour of congestive cardiac failure (loculated pleural effusion) Features suggestive of malignancy • Clinical: older age; COPD; previous malignancy; environmental exposures; haemoptysis; lung cancer in first degree relatives • Radiological: speculated appearance

• Arteriovenous malformations (Osler-Weber-Rendu disease) mucus plug(postoperative)

• Empyema with collapse/consolidation • Post-pneumonectomy: elevated gastric bubble; leftward shift of mediastinum; surgical clips in the left hemithorax in the vicinity of the left main stem bronchus With mediastinum pushed to opposite side • Pleural fluid: large pleural effusion (often malignant); chylothorax; haemothorax; empyema • Mesothelioma • Diaphragmatic hernia

lobar; obstructivesecondary to tumour, foreign body • Cystic adenomatoid malformation • Tension pneumothorax • Diaphragmatic hernia