الفهرس 
Body Temperature RegulationOnly 14 pages are availabe for public view
 |  | from | 143 |  |  |
| | | from | 143 | | |
Abstract
Body temperature is well regulated through a balance between heat production and heat loss at any given time. However, core temperature is maintained with a few tenth of 1oc by a complicated system of senses, depending on various positive and negative feedback mechanisms. The skin temperature is directly affected by the environment. The gradient between skin and core temperature (usually2-4oc) is inconstant and varies both between different individuals and within the same individual.
The ideal system for measuring temperature should provide reliable and reproducible values safely and conveniently. In order of accuracy, the most accurate methods for temperature measurement are pulmonary artery and urinary bladder thermistors, oesophageal and rectal probes, while less accurate methods include oral probes, infrared ear thermometers, axillary thermometers and chemical dots.
Fever is being defined as a core temperature above 38oc. However, a variety of definitions are acceptable depending on how sensitive an indicator of thermal abnormality an ICU practitioner wants to utilize.Fever is an adaptive process where normal body temperature is set at a higher level in response to circulating pyrogens. Fever is a sign of inflammation not a sign of infection, so any event which can provoke an inflammatory response is capable of elevating body temperature. There is no relationship between the degree of elevation of body temperature and the severity of tissue injury. In fact, approximately 50% of fevers in the ICU are not the direct result of infection.
ICU patients frequently have multiple infectious and non-infectious causes of fever, necessitating a systematic and comprehensive diagnostic approach. Pneumonia, sinusitis and blood stream infections are the most common infectious causes of fever. Other non-infectious causes of fever are diagnosed only after exclusion of all infectious causes of fever at first and they may include, cerebral infarction, cerebral hemorrhage, seizures, myocardial infarction, pulmonary emboli, systemic lupus erythematosus, pancreatitis, deep venous thrombosis, drug fever and postoperative fever within the 1st 48hours.
Hyperthermia has multiple effects on various organs and systems as well as on metabolism. It may cause cardiac ischemia, arrhythmia and hypotension in patients with underling heart disease. It may also worsen the condition of neurosurgical and cerebrovascular accidents patients as it increases the levels of circulating catecholamine and increases oxygen consumption leading to more tissue injury. On The other hand, it has been proven that hyperthermia inhibits bacterial growth and viral replication.
Fever is managed through general and definitive measures. The general measures include, external cooling techniques, antipyretics and antishievering drugs. The definitive measures are directed towards the offending cause of fever, whether, infectious or non-infectious, while providing appropriate cardiovascular and metabolic support.