What is cough? Cough is a protective and physiological reflex aimed at maintaining an open airway. Cough involves rapid expulsion of air at high velocity from the respiratory airway which expel irritants and excessive secretions from respiratory tract. Cough
Coughing is under voluntary and involuntary control and consists of 3 phases. Inspiratory : initiated by taking a deep breathe Phase and results in maximal dilation of the lungs. Compressive : closure of the glottis followed by phase contraction of thoracic and abdominal muscles against a fixed diaphragm. Expiratory : sudden glottis opening results in phase the explosive release air. Cough - Physiology
Classification of Cough: A cough can be classified by its - Duration , Character , Quality , and Timing. Classification as per the Duration of Cough: Acute (of sudden onset): Present < 3 weeks, Subacute : Present between 3 and 8 wks, Chronic : L asting > 8 weeks. Types of Cough
1. Acute Cough Cough which comes all of a sudden, 1. Dry cough 2. Productive cough 3. Bronchospastic / Asthmatic cough Most commonly relates to - 1. Viral – induced lower respiratory tract infections. 2. Post-nasal drip resulting from rhinitis or sinusitis. 3. Throat - clearing secondary to laryngitis or pharyngitis. Types of Cough
Cough is present between 3 and 8 weeks . The most common causes: Post infectious Cough. Acute Sinusitis. Asthma . 2. Sub-acute Cough:
Cough lasting for more than 3 weeks. Most Important Causes :
It frequently wakes up the patient during the night or the early hours of the morning.
6. Bronchospastic (Asthmatic) Cough
Characteristics of Cough Originating at Various Levels of Respiratory Tract : Origin Causes Characteristics Pharynx Post nasal drip Usually Persistent. Larynx Laryngitis, tumor, whooping cough, croup Harsh, barking, painful, persistent, often associated with strider. Trachea Tracheitis Painful Bronchi Acute Bronchitis and COPD Asthma. Bronchial Carcinoma Dry or Productive, , worse in mornings. Dry or productive, worse at night. Persistent often with haemoptysis. Lung Parenchyma Tuberculosis Pneumonia Bronchiectasis Pulmonary edema Interstitial Fibrosis Productive, often with haemoptysis. Initially Dry, Productive later. Productive Often at night ( may be productive) Dry, irritant and distressing.
Respiratory tract fluid - increases during infections
During RTIs or when lungs are exposed to foreign particles secretion increase in order to:
Dilute irritants, if any,
Drive away foreign bodies and unwanted particles,
Respiratory Tract Fluids
When respiratory tract is contaminated by – Oropharyngeal cells, bacteria, food particles and saliva, … it is called sputum. What is Sputum? ⁺ Phlegm is a sticky material from patient ’ s mucous membranes in the respiratory system. During Cold it might be yellowish brown . During an infection, it might be greenish brown. Normal phlegm is usually clear .
Actions of Anti-Cough Preparations Mucolysis Mucokinesis Expectoration Breaking down of the long, complex, muco polysaccharide fibers to facilitate better expectoration. Upwards movement of the mucous (mainly, gel layer of the Respiratory Tract Fluid). Driving away of respiratory tract fluid, done by liquefying the secretions so that extraneous (foreign particles, bacteria and the line) material can easily be thrown out
Rarely : Respiratory failure and coma, leading to death
Reduce ciliary motility of respiratory tract.
Interact with alcohol, antipsychotics, anti-depressants, anti-histaminics and anti-cholinergics.
Contra-indicated in respiratory, liver, cerebral diseases and endocrine disorders.
Anti-tussives (Narcotics) – Side Effects
These are a group of centrally acting anti-tussives without the narcotic properties which include – Noscapine and Dextromethorphan . Non- Narcotic Anti- Tussive
Drug Therapy of Cough Class Drug Name Action Antihistamines Cetirizine, Levocetrizine, Diphenhydramine, Chlorpheniramine maleate (CPM) Block effects of histamine in allergic cough. Anti-tussive (Cough suppressants) Codeine, Pholcodeine, Noscapine, Dextromethorphan To suppress the cough reflex. Demulcents (Soothing Agents) Lozenges, cough drops, linctuses containing syrup. (glycerin, liquorice), and menthol (local action) To sooth the respiratory mucosa. Expectorants Reflexly acting - Ammonium chloride (local action), Potassium chloride. Directly- Guaiphenesin (local action), Sodium and Potassium citrate, Potassium iodide. To increase mucus clearance. Mucolytics Bromhexine (local action), Carbocisteine to liquefy the respiratory secretions for easy expectoration. Decongestant Ephedrine, phenylephrine , and topical drugs like oxymetazoline, xylometazoline are widely used as decongestants. Phenylephrine HCL a synthetic sympathomimetic agent, Sympathomimetic agents are a vasoconstrictor and pressor drug chemically related to epinephrine and ephedrine.