Pricniples of Anesthesia (Mod 1) Flashcards
What is Anesthesia?
- Generalized vs regional?
When there is a reduction and lack of perception of all sensations (sensation and motor nerve signals). Often described as a state of reverisble loss of sensation and unconsciousness.
- General anethestics induce generalized, reversible depression of the CNS involving the entire body via combo of IV agents and inhalation agents
- Regiona Anesthetics usually involves full/partial depression of sensation in a area via spinal cord block or local anesthetics
What does the Anesthetic state include? (4)
- aka what are the primary desired affects?
- loss of consciousness
- Amnesia
- Immobility (lack of response to noxious stimuli)
- Some analgesia
What are secondary desirable effects provided by anaesthetics that could be useful during Sx?
- Muscle relaxation
- Loss of autonomic reflexes
- Analegsia
- Anxiolysis
Where is generalized anaesthetics most concentrated?
Distribute well to all parts of the body, but most concentrated in the fatty tissue
Where is the primary site of action that is affected/disrupted by Anesthesia?
The CNS
- Ensue from action in the brainstem, midbrain, and cerebral cortex (Suprasternal region)
How is immobility caused by Anesthesia?
Caused by depression of both the supraspinal and spinal sensory and motor pathways
What are the 4 stages of Anesthesia?
- Induction
- Maintenance
- Emergence
- Recovery
What is the Induction phase of Anesthesia?
Induction is the rapid and safe transition in states of unconsciousness
- Time elapsed between the admin of anesthetic and the development of effective surgical anesthesia
What is the Maintenance phase of Anesthsia?
Time during which the Pt is surgically anesthetize
What is the Emergence phase of Anesthsia?
Transition from general anesthesia to consciousness
What is the Recovery phase of Anesthsia?
Time from d/c of anesthetic drugs until consciousness if fully recovered
- when fully conscious, they’re in recovery
4 Stages of Anesthesia?
- Analegsia or Disorentation
- Excitement (hyperexcitable state)
- Surgical Anesthesia
- Medullary Depression/Overdose
Can stages of Anesthesia be skipped?
No, they need to transition from stage to stage.
- The most dangerous stage is stage 2 (hyperexcitable state)
What is Stage 1 Anesthesia (Analgesia/disorientation)?
Period between admin of induction agent and loss of consciousness
- Pt is sedated but conversational
- Breathing is slow and regular
- stage ends w/loss of consciousness
What is Stage 2 Anesthesia (Excitement)?
Short Dangerous stage, you wanna move quick in this stage. Depends on dose and admin.
- Paradoxical excitation from loss of conscious to onset of automatic breathing
- Uncontrolled movements; period of involuntary movements
- Resp can be irregular w/breath holding
- Excitement, delirium and combativeness.
- Eyelash reflex disappears, but other reflexes remain intact
- Elevated hemodynamic status
What is Stage 3 Anesthesia (Surgical Anesthesia)?
Sweet spot for Anesthesia
- Normal automatic function but unconscious
- Big risk of resp depression bc of intercostal paralysis which means shallow rests
- loss of laryngeal reflexes (safe to intubate/extuabte)
What is Stage 4 Anesthesia (Medullary depression)?
Overdose; too much anesthetic agent relative to amount of surgical stimulation
- Respiratory arrest (cardiac can occur too)
- Fixed and dilated pupils (eyes don’t react)
- Hypotensive, weak, and thready pulse bc of suppression of cardiac pump and vasodilation
Generally what are the hallmarks for each planes of stage 3 surgical anesthesia?
- Hint what is the hemodynamic, muscle, and/or vital profile of each stage
- 4 planes
- Light anesthesia (normal vital profile and tone, poor/no swallow)
- Moderate anesthesia (Elevated normal vitals, relaxed muscle tone, loss of laryngeal reflex)
- Deep anesthesia (target) (closed eyes + resp depression, low vitals and flaccid tone)
- Overdose ( jerky, irregular RR; apnea, no reflexes)
Nystagmus?
Eyes jitter back and forth rapidly
- Agents like Propofol and ketamine can cause this reaction to the eyes
What is Plane 1 of Stage 3 Anesthesia?
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Plane 1
- Depth: Light anesthesia
- Regular RR
- Strong pulse
- Normal BP
- May respond to surgery with movement
- Normal pupil size; PERRLA; nystagmus may be present; Eyelid reflex lost
- Muscle tone present
- Reflexes: Swallowing is poor or absent; others present but diminished
What is Plane 2 of Stage 3 Anesthesia?
edit
Plane 2:
- Depth: Moderate
- RR is automatic and regular with intermittent cessations of respiration
- HR strong, approaching tachycardic
- Loss of laryngeal reflex
- Hypotension
- HR and RR may increase in response to surgery
- Pupils slightly dilated. Pupil response is sluggish
- Relaxed muscle tone
- Majority of reflexes absent
What is Plane 3 of Stage 3 Anesthesia?
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Plane 3:
- Depth: Deep
- Targeted level of procedures requiring general anesthesia
- Closed eyes(hallmark)
- Respiratory depression (hallmark)
- Complete relaxation of the intercostal and abdominal muscles
- Pulse less strong
- Increasing hypotension
- No response to surgery
- Loss of pupillary light reflex
- Flaccid tone
What is Plane 4 of Stage 3 Anesthesia?
edit
Plane 4:
- Depth: Overdose
- Jerky, irregular RR; apnea
- Paradoxical ribcage movement (diaphragm paralysis)
- Bradycardia
- Significant hypotension
- No response to surgery
- Flaccid tone
- No reflexes
what are the 3 phases of Anethesia care
- Preoperative phase
- Intraoperative phase
- Post operative phase
What is involved in the Preopartive phase of Anethesia Care?
- Preop assessment; involves detailed assessment of risk that determines if they are fit for the procedure
- Choice of Anesthesia (options based on pt status and procedure
- Premedication
What is included in the preoperative assessment?
Detailed assessment of comorbid disease, fitness level, addressing patient concerns. **determines if they are fit for the procedure)
- What is the indication of the proposed surgery
- Addressing patient concernns
What are premedication considerations of anethesia care?
What conditions require stabilization before surgery (uncontrolled htn)
- What can be prescribed to optimize the surgery
- What can be d/c to optimize surgery
What considerations are included in the intraoperative phase of Anesthesia care?
Plans in relation to monitoring need to be kept in mind when procedure is ongoing.
- Physiologic monitoring and vascular access (plan based on preop assessment)
-
General anesthesia
(plan of induction, maintaince, and emergence meds used for each stage, airway/vent management?) -
Regional Anesthesia
(plan for anesthetic block, i.e epidural)
What are types of ames ethic blocks?
Infiltration via spinal route, epidural, or peripheral
What are considerations for postoperative anethesia care?
Patient is recovering (PACU)
- special monitoring or treatment based on surgery or anesthetic where they basically follow up with the pt post op
- Pt may require differing levels of post op pain control via pea, opioids, acetaminophen, nsaids etc. etc.
How does vapor pressure relate to anesthetic gas?
- Don’t worry about memorizing
edit
Most anesthetic gasses are volatile liquids in closed containers.
- Basically, the molecules transition from a liquid to gas phase really easy, directly correlated w/temperature.
- don’t worry about this last bit but…increase in temp increases ratio of gas:liq molecules, which increases vapor pressure
Boiling points of
- Sevoflurane
- Desflurane
- N20?
- Don’t worry about memorizing
All in deg celsius
- Sevoflurane: 58.5
- Desflurane: 22.8
- N2O: -88
- Remember, the greater the pressure, the higher the boiling point
Why is Desflurane a unique anesthetic gas?
It a volatile gas that requires a special vaporizer for proper utilization of the gas. W/O it, the gas would boil off and the patient would most likely wake up.
- the vaporizer provides a external heat source for sig heat loss associated w/desflurane vaporization
What is latent heat of vaporization
- Don’t worry about memorizing, just review if you have time.
latent heat of vaporization = number of calories needed to change 1g of liquid into a vapor w/o changing temp
Why is the hyperexcitable state of anesthesia (stage 2) dangerous?
The excitement or delirium stage is dangerous due to increased sympathetic nervous system activity. The following can be expected:
- increased HR, BP, and RR
- Delirium and involuntary movement
- Laryngospasm and hypertension
What are the hallmarks of stage 3 Anesthesia (surgical anesthesia) ?
- Respiratory depression (needs vent support)
- Ceased eye movements
What does paradoxical ribcage movement suggest?
Diaphragm paralysis
What sections of the body are included within the supraspinal region?
- Brainstem
- Midbrain
- Cerebral cortex
