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Flashcards in Quiz 2 Deck (34):


Minimum Aveolar Concentration

  • Measures potency of drug
  • Determines average setting used to produce surgical anesthesia
  • Lower the MAC, the  more potent the anesthetic agent and lower vaporizer setting
  • Isoflurane in dog: 1.3% MAC

Vaporizer setting:

1XMAC = Light surgical anesthesia

1.5XMAC = Moderate

2XMAC = Deep

MAC may be altered by age, metabolic activity, body temperature, disease, pregnancy, obesity, and other agents present


Isoflurane & adverse effects/Pros

Halogenated Organic Compound

Vapor pressure:  240mm Hg (high)

MAC: 1.3% - 1.63%

Blood gas parition coefficient: 1.46 (low)


Adverse effects

Depresses respiratory system

Provides no analgesia after anestheisa

Can provide carbon monoxide when exposed to desiccated (dry) carbon dioxide absorbent.




Maintains cardiac output, heart rate, rhythm

Few cardiovascular adverse effects

maintains cerebral blood flow

Eliminated through the lungs

Induces good muscle relaxation

Low rubber solubility

Stable at room temp

no preservatives

Low blood gas partition=rapid induction & recovery





Blood gas partition


Sponge effect

Measures solubility of gas anesthetic in the blood compared to alveolar gas (air).

Indicates Speed of induction & recovery

Low blood gas parition agent -> more soluble in alveolar gas and less in blood -> faster induction & recovery


Sponge effect

Agent is absorbed into blood & tissues (high blood gass partition coefficient. More soluble in blood than alveolar gas)



Vapor Pressure


Volatile agent vs Nonvolatile agent

Tendency to evaporate

Volatile agents: High vapor pressure, needs precision vaporizer to control delivery

Sevoflurane, Isoflurane, Desflurane, halothane


Nonvolatile agent: Low vapor pressure




High vapor pressure

Halogenated organic compound


MAC: 2.34% - 2.58%

Vapor pressure: 160mm Hg (High) - needs precision vaporizor

Blood gas partition coefficient:  lower than isoflurane


Adverse effects

Depresses respiratory system

Some paddling & excitment during recovery

No analgesic effect



Low blood gas parition = rapid induction and recovery than isoflurane

Minimum cardiovascular depression

Eliminated by lungs

Maintains cerebral blood flow

Induces good muscle relaxation



Monitoring Patient safety (anesthesia)



Vital signs: Response to homeostatic mechanisms to anesthesia

  • Heatr rate
  • Heart rythmn
  • Mucous membrane color
  • Capillary refill time
  • Respiratory rate
  • Respiratory depth
  • Blood pressure
  • Pulse strength
  • Temperature


Reflexes: Involuntary response to stimuli

  • Palpebral
  • Corneal
  • Pedal
  • Swallowing
  • Laryngeal
  • Papillary light Reflex


Other Indicators of Anesthetic Depth: spontaneous movements

  • Muscle tone
  • Eyeball position
  • Puspil Size
  • Nystagmus (rapid eye movement)
  • Salivary/Lacrimal secretions
  • Heart rate
  • respiratory rates
  • response to surgical stimuli



Heart Rate/Rhythm  Instruments


Esophageal Stethoscope


BP monitor (Doppler blood flow detector)


Circulation Instruments & Indictators

Capillary Refill Time:  Should be less than 2 seconds

Blood Pressure:  Force exerted on arterial walls

Systolic: contraction of lt. ventricle (Measureable by all  BP monitors)

Diastolic: Pressure that remains in the arteries during rest phase between contractions. (Not always measurable)

Pulse Strength:  Rough indictor of BP

  • Difference b/w systolic, diastolic, vessel size etc.
  • Palpate peripheral artery (femoral, lingual, dorsal pedal, facial etc)



Mean Arterial Pressure

The average pressure through the cardiac cycle

Best indicator of blood perfusion to internal organs


Normal: 60-150mm Hg

Below 60mm Hg is critical


Blood Pressure Monitors

Blood Pressure:  Force exerted on arterial walls

Systolic: contraction of lt. ventricle (Measureable by all  BP monitors)

Diastolic: Pressure that remains in the arteries during rest phase between contractions. (Not always measurable)


Direct readings

  • Catheter inserted into artery.
  • Most accurate
  • Invasive

Indirect readings

  • External sensor and cuff
  • Noninvasive
  • cuff is placed over superificial artery
  • Doppler and oscillonmetric common methods
  • Sphygmomanometer


PaO2 vs SaO2 Physiology

PaO2: Partial Pressure

  • Measures unbound, free O2
  • Dissolved in Plasma
  • Adequate O2 for metabolic process
  • Normal:  80-120mm Hg in arterial blood (1.5% total content)


SaO2: O2 Saturation percent

  • % of hemoglobin bingding sites occupied by oxygen
  • Normal:  Greater 97%


PaO2 decreases: SaO2 decreases (not at the same time)




PaO2 vs SaO2 Instruments

Pulse Oximeter: Measures O2 Saturation & heart rate

  • Normal: 95%+
  • Hypoxemic:  90-95%
  • Therapy required: 90%
  • Medical emergency: 85% for more than 30 secs.


Transmission probes (clothes pin) on tongue, pinna, lip

Reflective probes on hollow organ - esophagus or rectum


Blood gas analyzers: Measures Partial pressure


Respiration vs Ventilation

Respiration: Process where O2 is supplied to the tissues and CO2 is eliminated from the tissues


Ventilation: Movement of gas in and out of the aveoli


Ventilation indicators

(RR rate)

  • Observe thoracic wall movement
  • Observe breathing bag resevior
  • Esophageal stethoscope
  • Auscultation of breath sounds with stethoscope
  • Use respiratory monitor
  • capnography

RR: number of breaths per min

Tidal Volume (VT) - amount of air inhaled during one breath 



 Rapid respiratory rate




Tidal Volume (VT)






  • Amount of air inhaled during one breath 
  • Watch chest wall movements
  • watch reservoir bag
  • Use respirometer

Hypoventilation:  shallow breathing, subnormal tidal volume. Can cause atelectasis (collapsed lung)

Hyperventilation: elevated tidal volume. can cause Hypercapnea (increase in CO2 in blood)

Apneustic:  prolonged paused b/t inspiration and expiration

Dyspnea: labored breathing


Respiration Instruments

Apnea Monitor

Warns if patient hasn't taken a breath in a set time

Detects temperature differences b/t inspired air and expired air



  • Measures CO2 in air that is inhaled and exhaled
  • End Tidal CO2 monitor (ETCO2)
  • Reflects Arterical CO2 levels


Mainstream: sensor placed b/t endotracheal tube and breathing circcuit

Sidestream:  sensor located in computer monitor where air is pulled by a tube that is attached b/t endotracheal tube and breathing circuit

Inspiration:  CO2 is 0mm Hg

Expiration:  CO2 is 35-45mm Hg



ACVA Objectives of recording information during anesthesia

Record all drugs administered from pre anesthetic period to recovery (dose, route, time etc.)

Monitor variables every 5-10 mins. (HR, RR, BP)

Record any unusual circumstances for legal reasons



Local Anesthesia Pros and Cons


  • Low cardiovascular toxicity
  • Inexpensive
  • Minimum recovery time
  • Excellent pain control



Tissue Irritation

Systemic toxicity

Loss of motor neuron function

Allergic reactions



Local Anesthesia Routes & Type

Chemical agent on sensory neurons to disrupt nerve impulse transmission

Not the same as general anesthesia - does not affect the brain

does not have sedative effect



Topical - applied to skin, Lidocaine, Bupivacaine

Infiltration - Local anestheticinjected into tissues proximal to target nerve (SQ, IM, ID)

Epidural - deposited in epidural space b/t spinal cord and vertebrae



  • Lidocaine
  • Bupivacaine
  • Procaine
  • Mepivacaine





In dogs:  between L7 and S1



Ring Block

Line of local anesthetic that completely encircles the anatomic part


Pain Pathway

aka Nociceptor: tissue injury

  • Transduction - Transforms stimuli into sensory electrical signal (Action potential)
  • Transmission - Impulse travels to spinal cord
  • Modulation - Impulse is amplified or suppressed
  • Perception - Impulses transmits to the brain and processed


Physiologic pain

"Ouch pain"

Minimal tissue injury



Use of more than one type of analgesic

Targeting 2 or more of the receptors. Different drug will target different receptors


Untreated pain

  • Immune system suppression
  • inflammation and delayed wound healing
  • patient suffering
  • Anesthetic risk and increase in anesthesia doses
  • wasting


Physiological changes from pain

  • Change in activity
  • Reluctant to lie down
  • Vocalization
  • Change in facial expression
  • Change in attitude
  • Constantly shifting postion


Pain Scale

Verbal rating scales

simple descriptive scales - overall assessment of pain

numeric rating scales

visual analogue scales

comprehensive scales


Buprenex vs Butorphanol


Good nursing care

Comfortable bedding

quiet surrounding

clean cage

Opportunity to urninate and deficate

comfortable postion



ET Tube


  • Overinflation of cuff
  • Obstructed ET tube
  • waiting too long to remove the tubes
  • improper cleaning
  • vagus nerve stimulation


Proper placement of ET Tube

  • Check the resevoir bag
  • Check for fogging on ET during exhalation
  • palpate neck
  • revisualize larynx
  • any coughing




Anesthetist role during recovery

  • discontinue administration of all anesthetic agent
  • monitor patient on continual basis
  • administer O2
  • Administer reversal agents
  • Extubate patient
  • Nursing care: warm patient, patient hygiene
  • Provide analgesia


Cause of hypothermia

  • exposed skin and body cavity
  • inability to shiver
  • less heat generation due to lowered metabolic rate
  • vasodilation from anesthesia
  • patients on a non re-breathing system