Quiz 2 Flashcards
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
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
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
Methoxyflurane
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
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
Stethoscope
Esophageal Stethoscope
Electrocardiography
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)
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
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.
Types:
Transmission probes (clothes pin) on tongue, pinna, lip
Reflective probes on hollow organ - esophagus or rectum
_Blood gas analyzer_s: 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
Tachypnea
Rapid respiratory rate
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
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
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
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
Advantages
- Low cardiovascular toxicity
- Inexpensive
- Minimum recovery time
- Excellent pain control
Disadvantages
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
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
Epidural
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
Multimodal
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
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
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
