Chem and Phys Test 1 Flashcards
(115 cards)
Perioperative Heat Loss Timeframe
The patient core temperature drops the most in the first hour of induction.
Due to impairment of vasoconstriction and shivering responses.
Temperature stops dropping once it reaches 34.5 C
General anesthesia and temperature
Vasoconstriction is reduced and heat in the core moves to the periphery allowing core temperature to drop to anesthetic induced lowered threshold for vasoconstriction. Core to peripheral heat redistribution causes 0.5-1.55C drop in core temperature in the first hour of anesthesia
Thermoregulatory Vasoconstriction
Maintains temperature gradient between the core and periphery between 2-4C. Core (head, chest, and, pelvis) is insulated from environment by peripheral compartment
Most significant process in which patients experience heat loss during anesthesia
Radiation; accounts for 60% of heat loss
Which type of heat loss occurs when skin is prepped Chloaprep
Evaporation: warm heat from body causes liquid skin prep to turn to vapor.
Evaporation
Process in which liquid is changed to gas; requires energy to break hydrogen bondsBreathing causes heat loss through exhaled water vapor. Decrease gas flow rates, use humidification with patient who are intubated.
Complications of Hypothermia ( <35C)
surgical site infection due to impaired vasoconstriction and decreased blood flow to area dehiscence bleeding due to impaired coagulation ventricular ectopy delayed drug metabolism increased length of hospital stay higher blood transfusion rates impaired host defenses thermal discomfort
Newton’s first law of motion
A body at rest or moving at a constant speed in a straight line will remain at rest or continue in a straight line at a constant speed unless it is acted upon by a force
Newton’s second law of motion
Force = mass x acceleration
The rate of change of momentum of an object is directly proportional to the momentum of the force applied.
Newton’s third law of motion
Every action has an equal and opposite reaction
When one object exerts a force on a second object, the second object exerts a force that is equal in magnitude and opposite in direction
Heat loss
Transfer of energy from a higher concentration of the a lower concentration
Radiation
Charged particles are accelerated and release electromagnetic wavelengths. Heat is then transferred from body to cooler environment. Vasodilation effect of anesthesia causes increased blood flow from body’s core to periphery. Cover body surfaces not being operated on lessens heat loss.
Convection
Heat has higher kinetic energy and rises due to less density. Cold air lower energy molecules due to greater density. As heat rises from body, colder molecules fall and are heated by the body’s warmth; creating air currents. Heat is lost from the body and air is warmed. Decrease the temperature in the room.
Conduction
Heat is transferred from warmer object physically touching cooler object. Ex: warm patient body on cool OR table. Place warm blankets on OR table.
Standard measure of force
Newton; kg*meter/second^2
average gravity on Earth
9.80665 m/s^2
1 newton
force of 100,000 dynes, Ex: SVR, PVR measurement
Vectors
magnitude and direction displacement: distance with direction velocity: speed with direction acceleration: how quickly speed changes force
Scalars
magnitude only; volume density speed mass time temperature distance work pressure
Resultant
addition of 2 vectors; must take into account value and direction
Velocity
displacement/time, 0 if end at the same location
meter/sec
Work
Work = force x distance (or displacement)
Amount of energy necessary to move an object from one point to another
If work is done on you –> you gain heat
If you do work on something –> you lose heat
Unit: Joule = kg* m^2 / s^-2
(no change in volume/energy/distance = no work done)
penetrating injury damage depend on what 3 factors
- type of wounding instrument (knife, missile (bullet or fragment)
- velocity of the missile at time of impact
- characteristics of tissue which it passes (bone, fat, muscle, blood vessels, nervous tissue, organs)
Lower velocity wounds
inflict injury by lacerating and cutting tissue.