Lecture 1 8/21/24 Flashcards
What is anesthesia?
loss of sensation in a body part/whole body
What are the characteristics of general anesthesia?
-drug-induced, reversible, and controlled
-patient is not arousable by painful stimulus
-signs of anesthetic depth vary
What are the characteristics of local anesthesia?
-drug-induced loss of pain sensation
-occurs in circumscribed body area
What are the characteristics of regional anesthesia?
-drug-induced loss of pain sensation
-in a larger but limited body area
What is analgesia?
absence of pain in response to a normally painful stimulus
What is balanced anesthesia?
general anesthesia achieved through use of multiple drugs and techniques
What is dissociative anesthesia?
cataleptic state induced by use of agents that transiently disrupt neurotransmission between thalamocortical and limbic systems
What is nociception?
neural process encoding noxious stimuli that can still occur during unconsciousness
What is sedation?
state of CNS depression with muscle relaxation and lack of awareness of surroundings
What is tranquilization?
behavioral change resulting from stress relief
What are the components of the pre-anesthetic patient evaluation?
-history
-physical exam, including BP and pain assessment
-lab testing
-imaging
Which aspects of patient history are most important for anesthesia?
-co-morbidities
-all medications
-prior anesthetic events/records
What aspects of the cardiovascular system should be evaluated prior to anesthesia?
-hx of exercise intolerance/cardiac disease
-murmurs and their characteristics
-pulse rate and quality
-heart rate
-rhythm
-blood pressure
-imaging of chest
What aspects of the respiratory system should be evaluated prior to anesthesia?
-hx of respiratory distress
-respiratory effort
-breathing pattern
-resp rate
-auscultation
-brachycephalic vs normal airway
-imaging of chest
What aspects of the CNS should be evaluated prior to anesthesia?
-hx of central neurologic disease
-mentation
-potential for increased intracranial pressure
-recovery concerns
Which patient-related considerations need to be considered when selecting anesthetic regimen?
-species and size
-age
-temperament
-species and/or breed specific sensitivities
-co-morbidities
Which procedure-related considerations need to be considered when selecting anesthetic regimen?
-duration
-nature
-invasiveness
-expected degree of pain at sx site
What is pre-anesthetic stabilization?
optimizing the current condition of the patient to improve prognosis
What should be corrected during pre-anesthetic stabilization?
-hypotension
-intravascular volume
-electrolyte and acid-base imbalances
-anemia and/or thrombocytopenia
-hypoproteinemia
-clotting abnormalities
-cardiac dysrhythmias
-respiratory abnormalities
What are the ASA scales?
1: normal patient with no disease
2: patient with mild systemic disease that does not limit normal function
3: patient with severe systemic disease that limits normal function
4: patient with severe systemic disease that constantly threatens life
5: patient that is moribund and not expected to live 24 hours without surgery
E: emergency patient
What are the uses of sedation?
-restraint
-minor diagnostic procedures
-medical procedures
-improved quality of GA induction, maintenance, and recovery
-euthanasia
Which routes of administration are most commonly used for general anesthesia?
IM and IV
What are the effects of IM administration?
-onset within 10-15 minutes
-peak effect within minutes to hours
-less predictable and more prolonged effects
What are the effects of bolus IV administration?
-onset almost instantaneous
-peak effect obtained rapidly
-short duration of action
-effects generally more intense
What are the effects of continuous IV administration?
-effect remains as long as it is delivered
-recovery after termination is slower
What are the effects of inhalation administration?
-peak effect occurs rapidly
-effect remains as long as it is delivered
-recovery after termination is rapid
What are the uses of anesthesia?
-surgery
-major diagnostic procedures
-medical procedures
-euthanasia
What are the three main components of general anesthesia?
-analgesia
-unconsciousness
-muscle relaxation
What is the dose-dependent continuum of events in general anesthesia?
-alert wakefulness
-lethargy and drowsiness
-unconsciousness
-coma
-death
What are the characteristics of Stage 1 anesthesia?
-right after administration of inhalant/injectable anesthetic starts
-consciousness still present
-patient exhibits CNS stimulation, ataxia, analgesia
What are the characteristics of Stage 2 anesthesia?
-consciousness altered
-common with inhalants
-uncommon with injectables
-patient exhibits intense CNS stimulation that may involve excitement and/or delirium
-potential for laryngospasm
What are the three planes of Stage 3 anesthesia?
-light
-medium/surgical
-deep
What is exhibited by patients in Stage 3 anesthesia?
-ceased eye movements
-eyes in ventromedial position
-intense muscle relaxation
-depressed breathing
What are the characteristics of Stage 4 anesthesia?
-severe medullary depression
-patient exhibits eyes in central position with no reflexes, muscle flaccidity, severe cardiovascular depression/arrest, and severe respiratory depression/arrest
-not reversible and precedes death
What occurs during the anesthetic maintenance period?
-patient is monitored for anesthetic depth and cardiorespiratory parameters
-patient’s organ function is supported with IV fluids, drugs to support CV system, and mechanical ventilation
-changes in inhalant/injectable anesthetic titrations are made to adjust patient’s depth
What are the possible morbidities experienced during anesthesia?
-hypotension
-hypoventilation
-regurgitation
-hypothermia
