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Fever - body temp over:
- rectal 38.0° C (100.4° F)
- oral 37.8° C (100.0° F)
- axillary 37.2° C (99.0° F)
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Mechanisms of Heat Loss:
- 1. Convection - air mvmt
- 2. Vasodilation - blood moved to skin, most effective with moderate temp elecations
- 3. Dec. Muscle tone - washed out feeling
- 4. Evaporation - sweat
- 5. Inc. respiration - Inc. RR
- 6. Voluntary mechanisms - stretch out, slow down, clothing
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Why do the elderly have poor temperature regulation?
They have decreased circulation, shivering, metabolic rate, vasoconstrictor response, perception of heat/cold, and absent sweating.
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What is the diurnal variation in temperature for adults?
36.8° ± 0.4° C. (98.2° ± 0.7° F.)
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How is fever different from hypothermia?
- Increase in hypothalmic set point.
- Shivering
- Peripheral vasoconstriction
- Increase heat production from liver
- Responds to antipyretics
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How is hypothermia different from fever?
- Unchanged hypothalamic set point
- Increase in heat>than indv ability to decrease heat
- No response to antipyretics
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Causes of hyperthermia:
- Heat stroke - exertional and nonexertional
- exercising in heat
- anticholinergics/rubber suits
- Drug induced
- Stimulants, MAO inhibitors, PCP, TCAs,hallucinogens
Endocrinology
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Central Serotonin Syndrome (Etiology)
Iatrogenic complication from use ofdrugs/dietary supplements with CNS 5-HT(serotonin) activity
Excess stimulationof 5-HT receptors in CNS.
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Central Serotonin Syndrome (Sx)
- Confusion, agitation, anxiety
- Hyperthermia, diaphoresis, tachycardia/tachypnea
- Myclonus, muscle rigidity, tremor, restlessness/ataxia
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Central Serotonin Syndrome (Tx)
D/C medications
- Basic support
- IV fluids
- Benzodiazepines for muscular rigidity or nondepolarizingneuromuscular blockers
- Cooling blankets
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Neuroleptic Malignant Syndrome (etiology/patho)
From therapeutic doses of neuroleptic medications –mortality up to 30%
- Rapid increase in dose orparenteral admin may increase risk of:
- Severe muscular rigidity
- Altered sensorium
- Hyperthermia
- Autonomic lability
- Myglobinemia
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Neuroleptic MalignantSyndrome (treatment)
Supportive &aggressive cooling, CV support
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Malignant Hyperthermia (Etiology/Patho/Prevention)
Disorder of skeletal musclemanifested ashypermetabolic statewhen given certain anesthetics (or succinylcholine)
Genetic Susceptability
Prevention: Avoidance
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Malignant Hyperthermia (Treatment)
Dantrolene
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Endocrine causes of hyperthermia
Thyrotoxicosis
Pheochromocytoma – catecholamine-secretingtumors of adrenal medulla
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Pyrogens (Il-1,IL-6, TNF, IFN) --> Fever
_____ released by macrophages and endothelial cells in response to infections, inflammation, and immune reactions --> targets hypothalmic endothelium -->release PGE2 --> inc. cyclic AMP --> Elevated thermoregulatory set point --> Heat production --> ____
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Exogenous pyrogens
- Microbial products
- Lipopolysaccharide complex in cell wall of Gram positive bacteria, viruses
- Microbial toxins
- E.g. Gram negative endotoxin
- Whole microorganisms
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Endogenous Pyrogens
- Small proteins that regulate immune,inflammatory, hematopoieticprocesses
- IL-1, IL-6
- tumor necrosis factor (TNF)
- Ciliary neurotrophic factor (CNTF)
- Interferon (IFN) α
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Cytokine stimulation
- ______ stimulated by:
- Bacterial
- fungal
- viral infection
- Inflammation
- Trauma
- Tissue necrosis
- Antigenantibodycomplexes
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Cytokines produced by
- Monocytes
- Lymphocytes
- Neutrophils
- other - glial cells
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