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The State Education Institution of Higher Professional Training The First Sechenov Moscow State Medical University under Ministry of Health of the Russian Federation. Department of Pathophysiology. Disorders of thermoregulation. Fever. Lecture presentation. Professor Pirozhkov S.V.
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The State Education Institution of Higher Professional Training The First Sechenov Moscow State Medical University under Ministry of Health of the Russian Federation Department of Pathophysiology Disorders of thermoregulation. Fever. Lecture presentation Professor Pirozhkov S.V. 2014-2015 education year
DISORDERS OF THERMOREGULATION HYPERTHERMIC STATES HYPOTHERMIC STATES FEVER HYPERTHERMIA HYPOTHERMIA ► Overheating ► Heat stroke ► Sun stroke ► Malignant hyperthermia ► Supercooling HYPERTHERMIC REACTIONS
Types of hypothermia Core body temperature Mild32°-35°С Moderate28°-32°С Severe < 28°C
PATHOLOGICAL COSEQUENCIESOFHYPOTHERMIA Decrease in bodyt° Posterior pituitary Dehydration Decreasedsecretion ofvasopressin Haemocon- centration Decrease insystemic BP Decreased reabsorption of water andNa+ Thrombotic diathesis Inhibition of clotting factors activation DIC-syndrome Poor clotting of blood. Significant blood loss in minor trauma.
Fever: ● typicalpathologicalprocess ● characterizedby an increase in body temperature ● caused by the effect of pyrogenic substances ● resulting from an increase in the set point of thermoregulation
PYROGENS ENDOGENOUS ЕXOGENOUS Products Products Non-infectious of tissueof hemolysis decay Infectious LPS Lipoteichoic (Gram--bacteria) acids (Gram+-bacteria)
SYMPTOMS THAT ACCOMPANY FEVER ● Backache ● Arthralgias ● Anorexia ● Somnolence ● Chills, rigor (profound chill with piloerection) ● Sweats ● Convulsions ● Changes in psychological status: irritability – delirium – obtundation
PATHOGENESIS OF FEVER Neuron of the thermoregulation center cAMP Brain cortex Behavioralresponse Adrenals Centers of the sympathetic n.s. Thyroid gland Shivering Spasm of the skin arterioles Increase in thermogenesis Preservation of heat
STAGES OF FEVER • The stage of temperature elevation. • The stage of maintenanceof increased body temperature. • The stage of normalization of body temperature.
TYPES OF FEVER according to the extent of the body temperature increase (in the arm pit) Subfebrile < 38°С Febrile 38°С - 39°С Pyretic 39°С - 41°С Hyperpyretic > 41°С
TYPES OF FEVER by the pattern of circadian body temperature fluctuation Sustained not exceeding 1°С Remittent 1.5°-2.0°С Intermittent > 2.0°С Hectic (septic) 3.0°-5.0°С
Causes of hyperthermia Failure of the heat loss mechanisms under the conditionof high environmental temperature Great increase in heat production surpassingthe capacity of the heat dissipation mechanisms
PATHOGENESISOF THE SUN/HEAT SHOCK OVERHEATING OF THE HEAD ACCRUINGARTERIALHYPEREMIA INCREASEDFILTRATION OF FLUIDIN THE BRAIN TISSUE COMPRESSION OF THE BRAIN. INCREASED INTRACRANIAL PRESSURE. PROGRESSIVEVENOUS HYPEREMIA HYPOXIA. ISCHEMIA. INJURY TO THE NERVOUSCENTERS OF THE BRAIN. DECREASED SYMPATHETIC TONEIN THE PERIPHERAL VESSELS, COLLAPSE SHOCK SEVERE POLYORGANICINSUFFICIENCY,DEATH