Fever and cough.pdf

Fever Body temperature is controlled by the hypothalamus , which receive two kinds of signals: 1- From peripheral nerves that transmit information from warmth/cold receptors in the skin 2- The other from the temperature of the blood bathing the region. A normal body temperature is ordinarily mainta...

Fever Body temperature is controlled by the hypothalamus , which receive two kinds of signals: 1- From peripheral nerves that transmit information from warmth/cold receptors in the skin 2- The other from the temperature of the blood bathing the region. A normal body temperature is ordinarily maintained, despite environmental variations, because the hypothalamic thermoregulatory center balances the excess heat production derived from metabolic activity in muscle and the liver with heat loss from the skin and lungs. The maximum normal oral temperature for healthy individuals is 37.2°C at 6 A.M. and 37.7°C at 4 P.M.;. In light of these values: An A.M. temperature of >37.2°C A P.M. temperature of >37.7°C would define as fever.  Infection , microbial toxins , mediators Fever Microbial toxins of inflammation, immune reaction Exo g pyr enou Heat conservation, oge s n heat production macrophages/ Cyclic moncytes,endothelial AMP cell &others Elevated thermoregulator PGE2 set point Pyogenic mediators : Endogenous IL-2,IL-6.TNF,INF pyrogen Hypothalemic endothelium Circulation Events require for fever AMP, adenosine 5'-monophosphate; IFN, interferon; IL, interleukin; PGE2 , prostaglandin E2 ; TNF, tumor necrosis factor. Chills and Rigor Chills: (felling of Rigor is a sever attack of coldness) ,Occurring shivering which may occur at the onset of due to high fever disease characterised by rapid rise in the temperature Types of fever 1-Continuous fever :temperature remain above normal level throughout the day and does not fluctuate more than 1 C0 in 24 hours e.g:- Lobar pneumonia ,typhoid fever and UTI 2- Intermittent fever :the temperature elevation is present only for a certain period later cycling back to normal e.g:- malaria 3- Remittent fever :temperature remains above normal throughout the day and fluctuate more than 1 C0 in 24 hours e.g:- Infective endocarditis  Hyperpyrexia A fever of >41.5°C is called hyperpyrexia. This extraordinarily high (i.e. hyperpyrexia) fever can develop in patients with:- 1-Severe infections 2- Patients with central nervous system disease the hypothalamic set point is elevated as a result of local irritation as trauma, hemorrhage, tumor, or intrinsic hypothalamic malfunction. The term hypothalamic fever is sometimes used to describe elevated temperature caused by abnormal hypothalamic function.  Hyperthermia Hyperthermia is characterized by an uncontrolled increase in body temperature that exceeds the body's ability to lose heat(with normal hypothalmic set point) In contrast to fever in infections, hyperthermia does not involve pyogenic molecules. It is important to distinguish between fever and hyperthermia since hyperthermia can be rapidly fatal and characteristically does not respond to antipyretics. Hyperthermia is often diagnosed on the basis of the events immediately preceding the elevation of core temperature—e.g. heat exposure , drugs that interfere with thermoregulation(malignant neuroleptic syndrome) ,some kind of cancer(in conjunction with treatment)and endocrine diseases. Hyperthermia associated with elevated muscle enzyme CK-MB Treatment Cooling the patient body Good hydration Antipyretic therapy antipyretic Cough ❖ Definition:- Cough is an explosive expiration , that provides a normal protective mechanism for clearing the tracheobronchial tree of secretions and foreign material. It is also one of the most common symptoms for which patients seek medical attention due to the discomfort from the cough itself and interference with normal lifestyle.  Cough is a normal protective mechanism ❖ Mechanism :- Coughing may be initiated either voluntarily or reflexively. As a defensive reflex it has both afferent and efferent pathways. The afferent limb includes receptors within the sensory distribution of the trigeminal, glossopharyngeal, superior laryngeal, and vagus nerves. The efferent limb includes the recurrent laryngeal nerve and the spinal nerves. The cough starts with a deep inspiration followed by glottic closure, relaxation of the diaphragm, and muscle contraction against a closed glottis. The resulting markedly positive intrathoracic pressure causes narrowing of the trachea. Once the glottis opens, the large pressure differential between the airways and the atmosphere coupled with tracheal narrowing produces rapid flow rates through the trachea. The shearing forces that develop aid in the elimination of mucus and foreign materials. ❖ Causes of cough :- The most common causes of cough can be categorized according to the duration of the cough. Acute cough (8 weeks) in a smoker raises the possibilities of chronic obstructive lung disease or bronchogenic carcinoma, taking an ACE inhibitor, postnasal drip (sometimes termed the upper airway cough syndrome), asthma, and gastroesophageal reflux(GERD). ❖ Approach to the Patient with Cough:- A detailed history frequently provides the most valuable clues for the etiology of the cough. Particularly important questions include: 1. History of chronic rhinitis 2. Voice or altered swallowing, harsh or painful cough/ retrosternal pain 3. Dry or productive 4. haemoptysis 5. worse in mornings/ worse at night 6. Persistent or not The general physical examination may point to a systemic or nonpulmonary cause of cough, such as heart failure or primary nonpulmonary neoplasm. Chest radiography may be particularly helpful in suggesting or confirming the cause of the cough. Pulmonary function testing is useful for assessing the functional abnormalities that accompany certain disorders producing cough. The general physical examination may point to a systemic or nonpulmonary cause of cough, such as heart failure or primary nonpulmonary neoplasm. Chest radiography may be particularly helpful in suggesting or confirming the cause of the cough. Pulmonary function testing is useful for assessing the functional abnormalities that accompany certain disorders producing cough. If sputum is produced, gross and microscopic examination may provide useful information. Fiberoptic bronchoscopy is the procedure of choice for visualizing an endobronchial tumor and collecting cytologic and histologic specimens ❖ Treatment Definitive treatment of cough depends on determining the underlying cause and then initiating specific therapy. Elimination of an exogenous inciting agent (cigarette smoke, ACE inhibitors) or an endogenous trigger (postnasal drip, gastroesophageal reflux) is usually effective when such a precipitant can be identified. In patients with chronic, unexplained cough, an empirical approach to treatment is often used for both diagnostic and therapeutic purposes, starting with an antihistamine-decongestant combination, nasal glucocorticoids, or nasal ipratropium spray to treat unrecognized postnasal drip.  Symptomatic or nonspecific therapy of cough should be considered when: 1. An irritative, nonproductive cough may be suppressed by an antitussive agent, which increases the latency or threshold of the cough center. Such agents include codeine (15 mg qid) or non narcotics such as dextromethorphan (15 mg qid). These drugs provide symptomatic relief by interrupting prolonged, self-perpetuating paroxysms. 2. A cough productive of significant quantities of sputum should usually not be suppressed, since retention of sputum in the tracheobronchial tree may interfere with the distribution of alveolar ventilation and the ability of the lung to resist infection(expectorant).