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Flashcards in Quiz 2 Deck (34):
1

MAC

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

2

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.

 

 

Pros

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

 

 

 

3


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)

 

4

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

Methoxyflurane

5

Sevoflurane

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

 

Pros

Low blood gas parition = rapid induction and recovery than isoflurane

Minimum cardiovascular depression

Eliminated by lungs

Maintains cerebral blood flow

Induces good muscle relaxation

 

6

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

 

7

Heart Rate/Rhythm  Instruments

Stethoscope

Esophageal Stethoscope

Electrocardiography

BP monitor (Doppler blood flow detector)

8

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)

9


MAP

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

10

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

11

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)

 

 

12


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.

Types: 

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

Reflective probes on hollow organ - esophagus or rectum

 

Blood gas analyzers: Measures Partial pressure

13

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

14

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 

15

Tachypnea

 Rapid respiratory rate

 

 

16

Tidal Volume (VT)

 

Hypoventilation

Hyperventilation

Apneustic

Dyspnea

  • 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

17

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

18

Capnograph

  • 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

 

19


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

 

20


Local Anesthesia Pros and Cons

Advantages

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

 

Disadvantages

Tissue Irritation

Systemic toxicity

Loss of motor neuron function

Allergic reactions

 

21

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

 

Routes

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

 

Types

  • Lidocaine
  • Bupivacaine
  • Procaine
  • Mepivacaine

 

 

22

Epidural

In dogs:  between L7 and S1

 

23

Ring Block

Line of local anesthetic that completely encircles the anatomic part

24

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

25


Physiologic pain


"Ouch pain"

Minimal tissue injury

26

Multimodal

Use of more than one type of analgesic

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

27

Untreated pain

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

28

Physiological changes from pain

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

29

Pain Scale

Verbal rating scales

simple descriptive scales - overall assessment of pain

numeric rating scales

visual analogue scales

comprehensive scales

30


Buprenex vs Butorphanol

31

Good nursing care


Comfortable bedding

quiet surrounding

clean cage

Opportunity to urninate and deficate

comfortable postion

 

32

ET Tube

Complications

  • 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

 

 

33

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

34

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