Hypovolaemia Health Dictionary

Usually a second infection with a different serotype of the dengue virus (see dengue fever). A primary infection at a young age is common finding. Age of patient with DHF is often less than 5 years, but young adults may be affected. Severe illness with abnormal vascular permeability, hypovolaemia and abnormal clotting mechanisms. Bleeding into skin or internally. Dengue shock syndrome may also be a complication.... dengue haemorrhagic fever

Fainting, or SYNCOPE, is a temporary loss of consciousness caused by inadequate supply of blood to the brain. It may be preceded by nausea, sweating, loss of vision, and ringing in the ears (see TINNITUS). It is most often caused by pooling of blood in the extremities, which reduces venous return (see CIRCULATORY SYSTEM OF THE BLOOD) and thus cardiac output: this may be due to hot weather or prolonged standing. Occasionally, fainting on standing occurs in people with low blood pressure (see HYPOTENSION), autonomic neuropathy (in which normal vasomotor re?exes are absent), or those taking antihypertensive drugs. A prolonged rise in intrathoracic pressure caused by coughing, MICTURITION, or VALSALVA’S MANOEUVRE also impedes venous return and may cause fainting. HYPOVOLAEMIA produced by bleeding, prolonged diarrhoea, or vomiting may also cause fainting, and the condition can be produced by severe pain or emotional upset. Cardiac causes, such as severe stenotic valve disease or rhythm disturbances (particularly complete heart block or very rapid tachycardias), may result in fainting (see HEART, DISEASES OF). Treatment must be directed towards the underlying cause, but immediate ?rst aid consists of laying the patient down and elevating the legs.... fainting

A core body temperature of less than 35 °C. As the temperature of the body falls, there is increasing dysfunction of all the organs, particularly the central nervous and cardiovascular systems. The patient becomes listless and confused, with onset of unconsciousness between 33–28 °C. Cardiac output at ?rst rises with shivering but then falls progressively, as do the oxygen requirements of the tissues. Below 17– 26 °C, cardiac output is insu?cient even to supply this reduced demand for oxygen by the tissues. The heart is susceptible to spontaneous ventricular FIBRILLATION below 28 °C. Metabolism is disturbed and the concentration of blood GLUCOSE and POTASSIUM rises as the temperature falls. Cooling of the kidneys produces a DIURESIS and further ?uid loss from the circulation to the tissues causes HYPOVOLAEMIA.

Severe hypothermia is sometimes complicated by gastric erosions and haemorrhage, as well as pancreatitis (see PANCREAS, DISORDERS OF). Infants and the elderly are less e?cient at regulating temperature and conserving heat than other age groups, and are therefore more at risk from accidental hypothermia during cold weather if their accommodation is not warm enough. Approximately half a million elderly people are at risk in Britain each winter from hypothermia. The other major cause of accidental hypothermia is near-drowning in icy water. Deliberate hypothermia is sometimes used to reduce metabolic rate so that prolonged periods of cardiac arrest may occur without tissue HYPOXIA developing. This technique is used for some cardiac and neurosurgical operations and is produced by immersion of the anaesthetised patient in iced water or by cooling an extracorporeal circulation.

Treatment of hypothermia is by warming the patient and treating any complications that arise. Passive warming is usual, with conservation of the patient’s own body heat with insulating blankets. If the core temperature is below 28 °C, then active rewarming should be instituted by means of warm peritoneal, gastric or bladder lavage or using an extracorporeal circulation. Care must be taken in moving hypothermic patients, as a sudden rush of cold peripheral blood to the heart can precipitate ventricular ?brillation. Prevention of hypothermia in the elderly is important. Special attention must be paid to diet, heating the home and adequate clothing in several layers to limit heat loss.... hypothermia

n. see hypovolaemia.... oligaemia

n. the rapid breakdown of skeletal muscle cells, with the release of myoglobin and other potentially toxic cell components. Blood levels of *creatine kinase are raised. It can result in *hyperkalaemia, *hypovolaemia, *myoglobinuric acute renal failure, and *disseminated intravascular coagulation. Causes include muscle trauma and crush injury, alcohol abuse, seizures, and medications (notably statins).... rhabdomyolysis