What usually causes Endocrine Diseases?
Abnormal amounts of Hormones
What are Hormones?
Substances made by one cell type that signals a response from another cell type
What are considered Peptide/Protein Hormones?
Insulin
Growth Hormone
ADH
Most Common
What are considered Steroid Hormones?
Cortisol & Aldosterone
Which types of hormones are water soluble?
Peptide/Protein & Catecholamines
What types of hormones are Lipid Soluble?
Steroid & Thyroid
Where do hormones work?
On specific receptors on the surface or inside the cell to start a cascade of reactions
How does the body control hormonal response?
Positive and Negative Feedback
What is Metabolic Rate?
Rate of Heat Liberation during chemical reactions
What is the difference b/t Direct & Indirect Calorimetry?
- Direct: Direct measure of heat made; difficult to peform, used in research
- Indirect:Measures O2 Consumption & CO2 Production
What increases Metabolic Rate?
Thyroxine (T4)
Testosterone
Growth Hormone
Fever
What decreases Metabolic Rate?
Inadequate Thyroxine (T4)
Sleep
Malnutrition
Which monitoring sites are defined as core body temperature?
Esophagus
Nasopharynx
External Auditory Meatus
Pulmonary Artery Catheter
How does Skin, Axillary, and Rectal temperature compare to core body temperature?
Skin: 3-4 C lower
Axilla: 1 C lower
Rectum: 1 C higher
Which part of the brain regulates body temperature and is the “Set-Point”?
Hypothalamus/Preoptic Nuclei
What are the Cardiac effects of Hypothermia?
↑O2 Consumption d/t Shivering
Arrhythmias
Ischemia
Can’t Defib < 30 C
What are the Pulmonary effects of Hypothermia?
↑Pulm. Vascular Resistance
Depressed Ventilatory Drive
↓Blood CO2
What are the Renal effects of Hypothermia?
Cold Diuresis & ↓Plasma Volume
How is the CNS effected by Hypothermia?
↓Cerebral O2 Consumption 7% per 1°C
↓MAC 5-7% per 1°C
Delayed Emergence
How does Hypothermia affect coagulation?
Decreases Coagulation and Platelets
Why does Hypothermia prolong NMBs and Delay Emergence?
50% Metabolism Reduction @ 30°C
60% Metabolism Reduction @ 25°C
Increased Plasma Concentration of Propofol & Fentanyl
How does Hypothermia contribute to Wound Infection?
Directly impairs immune system
Vasoconstriction = poor tissue perfusion
↓ABX Penetration
↓Phagocytic & Neutraphil Function
What are the Two Compartments of Body Temperature
Peripheral: limbs, skin, subq tissue - 1/3 of body’s heat
Core: thoracic & abdominal organs, brain - 2/3 of body’s heat
What are the temperature ranges for the core vs. peripheral?
Core: 36.6 - 37.4°C
Peripheral: 0 - 40°C
Maintained by Vasoconstriction
What is the normal Basal Heat production?
1.2°C per hour
How effective is shivering in producing heat?
Increases heat production by 300%
In what ways is Heat Loss?
- Radiation - 60% - pt. to environment
- Convection - 25% - air near skin moves heat away
- Evaporation - skin prep, open abdomen, respiration
- Conduction - 5% - direct contact b/t pt. & table
When would you see the biggest drop in temperature in the OR?
1st hr. after induction d/t vasodilation
Anesthesia inhibits vasoconstriction and decreases metabolic rate by 20-40%
1 unit of cold PRBC or 1 L of Fluid can decrease core temperature by ______?
0.25°C
Which population would heat loss be more pronounced?
Elderly: decreased BMR & autonomic neural fxn
Neonates: decreased autonomic neural fxn & increased surface area
Which med used to be the most commonly used for Post-Op Shivering?
Meperidine (Demerol) 25-50 mg - works on Mu & Kappa receptors
What are causes of Hyperthermia?
Thyrotoxicosis
Pheochromocytoma
Hypothalamic Injury
Neuroleptic Malignant Syndrome
What is the treatment for Malignant Hyperthermia?
Dantrolene: 2.5mg/kg q5min
