Inhaled Anesthetics Flashcards
Inhaled Anesthetics
Goal is to have enough pressure so the anesthetic gas goes from a higher pressure to a lower pressure. This involves getting gas from machine to the lungs, then from the lungs to the blood, then from the blood to the brain
Ultimate goal is _______ so the anesthetic level is maintained and doesn’t fluctuate
Equilibrium
Blood/Gas Partition Coefficient
Halothane (most _____ in blood)
Isoflourane (second most ____ in blood)
Sevoflourane
Nitrous Oxide
Desflourane
- 4, Soluble
- 4, Soluble
- 65
- 47
- 42
Inhaled Anesthetic/GABA
Binding of GABA is _____ by inhaled anesthetics, resulting in greater entry of _____ ions
Entry of Cl- hyperpolarizes the cell, making it more difficult to ______, therefore reducing neuronal excitability
Enhanced, Cl-
Depolarize
Partial Pressure (P)
Dalton’s Law: The total pressures (Ptot) of a mixture of gases is the ____ of the pressures each gas would exert if it were present _____
The goal is to achieve a _____ and _____ brain partial pressure of inhaled anesthetic
Sum, Alone
Constant and Optimal
Partial Pressure (P)
Brain (Pbr) and all other tissues _____ with the partial pressure of inhaled anesthetics delivered by arterial blood (Pa)
Arterial blood _____ with _____ partial pressure of anesthetics (PA)
Equilibrate
Equilibrates, Alveolar
Partial Pressure (P)
PA mirrors ____
PA is an index of _____ of anethesia, _____ from anesthesia, and anesthetic equal potency or (____)
Pbr
Depth, Recovery, MAC
Ventilation Rate
Minute Ventilation: ____ of all exhaled gas volume in ___ minute
Minute Ventilation Formula?
Normal minute ventilation?
Ex: At rest, normal person moves about 450 mL /breath at about 10 breaths/minute = 4,500 mL/min = 4.5 L/min
Sum, 1
MV = Tidal Volume x Breaths/min
Around 5L/min
Alveolar Ventilation
Volume of inspired gases actually taking part in ____ ______
_____ indicates alveolar ventilation
AV = ( ____ _____ - _____ _____) x Breaths/min
Gas Exchange
PC02
(Tidal Volume - Dead space)
Dead Space (Vd)
Any volume of inspired air that does not enter the ____ ______ areas of the lung
Airway (______) dead space: portion of breath which goes to the mouth, pharynx, etc., but does not enter the alveoli
______ dead space: portion of breath that enters alveoli which are ventilated, but not perfused
Gas Exchange
Anatomic
Alveolar
Determinants of Alveolar Partial Pressure (PA)
PA is determined by _____ (input) of inhaled anesthetic into alveoli minus the _____ (loss) of drug from alveoli into arterial blood
Delivery depends on: inhaled ______ ______ (PI), ______ ______ (how many lung units are being ventilated), and the ______ of the anesthesia breathing system (delivery)
Uptake (alveoli to pulmonary capillary blood) depends on: ______ of anesthetic in body tissues, _____ _____, and _____ to _____ partial pressure difference (A-vD)
Delivery, Uptake
Partial Pressure, Alveolar Ventilation, Characteristics
Solubility, Cardiac Output, Alveolar to Venous
Determinants of Alveolar Partial Pressure (PA) **Recap**
_______ ventilation
_______ breathing system
________
______ ______
______ to _____ partial pressure differences
Alveolar
Anesthetic
Solubility
Cardiac Output
Alveolar to Venous
Inhaled Partial Pressure (PI)
•Concentration Effect•
Impact of PI on the rate of rise of PA of onhaled anesthetic
The ______ the inspired concentration of the anesthetic agent, the more _____ the relative rise in _______ _______ of the agent
Anesthetic agents follow a ______ ______ from machine to ______ to ______ then to the ______
Higher ____ equals higher ______ ______
Higher, Rapid, Alveolar Concentration
Concentration Gradient, Alevoli, Blood, Brain
PI (inspired pressure of gas), Alevolar Concentration
Second Gas Effect
Reflects ability of high volume uptake of one gas to ______ the rate of increase of PA of a _______ administered “companion” gas
Large volume uptake of Nitrous Oxide ______ the rate of rise of PA of other gases (O2, volatile anesthetics)
Reflects increased tracheal inflow of all the inhaled gases (1st and 2nd) and concentration of 2nd gas in _____ lung volume due to ____ volume uptake of the 1st gas (concentrating effect)
Accelerate, Concurrently
Accelerates
Smaller, High
Second Gas Effect
Ability of large volume _____ of one gas (first gas) to _____ the rate of rise of alveolar partial pressure of a co-administered second gas
______ is used as the first gas
The effect is more applicable to an agent with _____ blood:gas solubility (solubility discussed more later)
Uptake, Accelerate
Nitrous (N2O)
Higher
Alveolar Ventilation
_____ alveolar ventilation promotes ______ (input) of anesthetics to offset uptake
Causes a more ____ rate of _____ in PA toward PI (inhaled partial pressure), resulting in _______
Decreased ______ is produced by ________ of the lungs, resulting in a decrease in _____ ______ ______
Increased, Delivery
Rapid, Rise, Induction
PaCO2, Hyperventilation, Cerebral Blood Flow
Alveolar Ventilation
A ______ in alveolar ventilation decreases ______ (delivery) and slows the establishment of PA and Pbr for ______
The ______ the alveolar ventilation: FRC ratio, the more rapid the rise of PA
5:1 in neonates (greater metabolic rate) and 1.5:1 in adults
_____ is _____ in neonates because of the ______ _____
Decrease, Input, Induction
Greater
Induction, Quicker, Metabolic Rate
Alveolar Ventilation
Inhaled anesthetics have a _____ dependent ______ effect on alveolar ventilation
______ _______ protective mechanism exists to prevent excessive depth of anesthesia when high PI is administered with _______ breathing
______ decreases parallel to _______ ventilation; anesthetic is _______ from tissues of high _______ to tissues of low _______
When concentration in brain falls below a certain threshold, ventilation _______ and the delivery of anesthetic to lungs is _______
Dose, Depressive
Negative Feedback, Spontaneous
Input (delivery), Decreased, Redistributed
Concentration, Concentration
Increases, Increased
Alveolar Ventilation
When a patient is breathing in a volatile anesthetic, you will typically see a ______ tidal volume and ______ respiratory rate (shallow, rapid breathing pattern)
Alveolar minute ventilation ______ because more anesthetic is going to the dead space. Low tidal volume breaths _____ alveolar minute ventilation
______ ______ is reduced by all volatile anesthetics. All inhaled anesthetics ______ the natural ventilatory response to ____ and ____
If CO2 increases, normally you would breathe _____, but inhaled anesthetics _____ that response
Decreased, Increased
Decreases, Decrease
Airway Resistance, Depress, CO2 and O2
Faster, Depress
Alveolar Ventilation
Normally, if we become ______, our body will respond with _______, but this response is greatly ______ by volatile anesthetics
Inhaled anesthics are altering peripheral and chemoreceptor functioning in a ____ dependent manner
The body’s protective ______ ______ mechanism (discussed earlier) is _____ with mechanical ventilation, especially when you ______ them and assume control for all of the patient’s _______
Hypoxic, Hyperventilation, Depressed
Dose
Negative Feedback, Lost, Paralyze, Breathing
Impact of Solubility
Alveolar ventilation influences the rate of rise of PA toward PI _____ in _____ anesthetics than in _____ soluble ones
In ______ soluble anesthetics, the rise of PA is _____, regardless of other factors (less soluble gas is in blood, faster it enters alveoli)
More soluble anesthetics have a greater _____ (in the blood), so increase in _____ will ______ rate of rise of PA; Hence why mechanical ventilation _____ the depth of anesthesia produced by a more blood _____ anesthetic
More, Soluble, Poorly
Poorly, Rapid
Uptake, Ventilation, Increase
Increases, Soluble
Solubility
Solubility in tissues and blood is denoted by a _____ _____; a ______ ratio describing how inhaled anesthetic distributes itself between two phases of _______
A blood:gas partition coefficient of _____ = the concentration of inhaled anesthetic in blood is ____ that of alveolar gases when _____ _____ is equal in both phases
A blood:brain partition coefficient of ___ = the concentration in blood is ____ that in the _____
Partition Coefficient; Distribution
Equilibrium
0.5, 1/2, Partial Pressure
2, Twice, Brain
Solubility
Partition coefficient reflects the relative ______ of each phase to ______ anesthetic, and is _______ dependent
Capacity, Accept, Temperature
Blood:gas Partition Coefficent
Rate of increase of PA toward PI is _____ ______ to the solubility of anesthetic in the blood
If blood:gas partition coefficient is high, a _____ amount dissolves in blood before _____ can occur between PA and Pa toward PI; meaning induction is _____
If blood:gas partition coefficent is low, a _____ amount dissolves in blood before _____ is reached; meaning rate of rise of PA and Pa is _____, and induction is _____
Inversely Proportional
Larger, Equilibrium, Slow
Smaller, Equilibrium, Rapid, Rapid
Blood:gas Partition Coefficent
Can offset high blood:gas partition coefficient (slower induction) by increasing ___ above that required for maintenance of anesthesia. This is called an ______ ______
This _____ induction, but sustained delivery at this level can cause _______
PI, Overpressure Technique
Speeds, Overdose
Blood:gas Partition Coefficent
Blood:gas partition coefficient is influenced by variations in ____, ____, and _____ content, as well as ____ of blood
There is ______ solubility of anesthetics in ______ blood, meaning these patients will have a more _____ induction (anesthetic agent won’t stay in blood- it will quickly move to lungs/brain)
Water, Lipid
Protein, Hct
Decreased, Anemic, Rapid
Blood:gas Partition Coefficent
(Recap)
States how ______ the anesthetic is in the blood
It is ______ related to ______ time of the anesthetic agent
_____ ______ gas in the blood = ______ induction via inhalation
______ ______ gas in the blood = ______ induction via inhalation
Soluble
Inversely, Induction
Less Soluble, Faster
More Soluble, Slower
Tissue:blood Partition Coefficient
Determines _____ of anesthetic into ______ and time necessary for ______ of tissues with Pa
Time for _______ is estimated calculating a _____ ______ for each tissue
For volatile anesthetics, __ time constants (5-15 minutes for Pa and Pbr to equilibrate and cause induction)
Uptake, Tissues, Equilibration
Equilibration, Time Constant
3
Tissue:blood Partition Coefficient
____ has a large anesthetic holding capacity with ____ blood flow, so time to equilibrate is ______ (25-46 hours)
Clinical Example: ________ may be a better agent for obese patient’s (quick off time) versus _______, which has more of a tendency to harbor in fat when gas is turned off
Fat, Low
Prolonged/Slower
Desoflurane, Sevoflurane
Tissue:gas Solubility
Concerns ____ tissues (muscles, vessel rich organs: heart, liver, kidney, brain) _____ for a given anesthetic agent
Predicts ______ ______ from anesthesia
______ tissue:gas ratios indicate that the gas is relatively ______ in tissues, therefore, emergence will be more _____
Lean, Affinity
Emergence Time
Lower, Insoluble, Rapid
Stages of Anesthesia
Stage 1
Begins with ______
Ends with loss of _______ (no _____ reflex)
Patient can still sense _____ (evidenced by increased HR and BP)
Induction
Consciousness, Eye-lid
Pain
Stages of Anesthesia
Stage 2
Delerium ______, uninhibited ______
Pupils ______ with divergent gaze
Potentially ______ response to noxious stimuli (Do not want patient stimulated at this time)
Stimulation may lead to ______ holding, muscular _____, ______, or ________
Excitement, Excitation
Dilated
Dangerous
Breath, Rigidity, Vomiting, Laryngospasm
Stages of Anesthesia
Stage 3
Where we want to be for ______
Centralized gaze with ______ of pupils
Regular ______
Anesthesia depth is ______ for noxious stimuli (when the noxious stimuli does not cause an increase in ______ response)
Surgery
Constriction
Respirations
Sufficient, Sympathetic
Stages of Anesthesia
Stage 4
Stay ____ from, this is too ____
Will cause _____
Pupils are ______ and ____-______
_______ resulting from complete CV collapse is possible
Away, Deep
Apnea
Dilated, Non-Reactive
Hypotension (may be a big sign that you need to turn your gas down)
Cardiac Output and Induction
Represented by ______ blood flow
Influences uptake and PA by _____ _____ either more or less anesthetic from alveoli
Increased CO: More _____ uptake and _____ induction
Decreased CO: speeds rate of rise in PA, _____ uptake and _____ induction
Pulmonary
Carrying Away
Rapid, Slowed
Less, Faster
Cardiac Output and Induction
Increased cardiac output ______ capacity of the blood to ____ anesthetic. This has the most infuence on _____ anesthetics
Some volatile agents _____ cardiac output, resulting in a ______ ______ response (Decreased CO due to excessive _____ leads to increased PA, increased ____, and subsequently, further reduced CO and cardiac ______ secondary to the increased anesthetic depth
Increases, Hold
Soluble (agents prone to dissolve more in blood)
Decrease, Positive Feedback
Dose, Depth, Depression
Recovery from Anesthesia
Rate of _____ of Pbr is reflected by decrease in PA
At conclusion of anesthesia, ______ of anesthetic in ______ depends on its _______ in the tissue and ______ of administration
Some tissues may not reach _____ with PA during maintenance
This is seen mostly in ______ anesthetics; Time to recover is ______ proportional to the duration of administration mostly in ______ anesthetics
Exhaled gases will be _____, unless fresh gas flow rate is _____
Decrease
Concentration, Tissues, Solubility, Duration
Equilibrium
Soluble, Prolonged, Soluble
Rebreathed, Increased
Recovery from Anesthesia
If your patient is not waking up, make sure you turned gas ____
Also make sure that you _____ oxygen flow rate (8-10 L/min)
Off
Increase
Diffusion Hypoxia
Happens _____ use of nitrous
When the nitrous is discontinued, nitrous diffuses rapidly out of the _____, into the _____, subsequently into the _____
This rapid _____ into the alveoli _____ alveolar gas and ______ oxygen, causing ______
Net result will be _______
After
Tissues, Blood, Alveoli
Flood, Dilutes, Displaces, Hypoxia
Hypoventilation
EEG Effects of Anesthetics
At ______, increase in frequency and voltage similar for all anesthetics (all gases have same effect at this point)
At ______, shift of voltage activity from ______ to ______ portions of brain
At ______, ______ in cerebral O2 requirement (may reflect transition from wakefulness to unconsciousness)
< 0.4 MAC
~ 0.4 MAC, Posterior to Anterior
~ 0.4 MAC, Decrease
CNS Effects - Seizure Activity
______ has fast frequency and high voltage on EEG, indistinguishable from changes produced by _____ activity
Twitching of ______ and ______ muscles occurs and can be initiated by repetitive ______ stimuli
_____, _____, and _____ are agents that have no seizure activity on EEG; they actually ______ convulsant properties
_____ may induce increased motor activity; withdraw in animals may indicate _____ ______
Enflurane, Seizure
Facial, Extremity, Auditory
Iso, Sevo, Des; Suppress
N20, Acute Dependence
CNS Effects
Evoked Potential
Volatile anesthetics cause a dose-related ______ in amplitude and ______ in latecy of cortical component of the ______ nerve somatosensory, visual, and auditory evoked potentials
Decrease, Increase
Medial
Cerebral Blood Flow
Volatile anesthetics at ______, produce cerebral _______, decreased cerebral vascular ______, and dose-dependent _____ in cerebral blood flow
At ______, _______ is most potent CNS vaodilator, secondary to ______, with ______ and _______ producing equal and less significant CNS effect
____ also increases CBF
Increased CBF occurs within _____ of anesthetic administration
Increased CBF and dilation not good for what patient population?
> 0.6 MAC, Vasodilation, Resistance, Increase
At 1.1 MAC, Halothane, Enflurane
Isoflurane and Desoflurane
N2O
Minutes
Patient’s with increased ICP or brain bleeds
Cerebral Metabolic O2 Requirements
Dose dependent ______
Decreases _______ requirement, leading to _____ CO2 production, causing ______ and ______ in CBF
Agents such as ______, ______, and ______ will equally reduce _____ and decrease CO2 production, causing _______ effects
For Neuro patients, use ____, _____, or ____ and avoid ______ or _____
Decrease
Metabolic, Decreased, Vasoconstriction, Decrease
Iso, Sevo, Des, CBF, Vasocontricting
Iso, Sevo, Des, Halothane, N2O
Cerebral Protection
In humans undergoing carotid endarterectomy, _______ appears to provide a degree of cerebral ______ (The CBF at which _____ changes appear is lower during administration, compared to other agents)
(may reduce the transient cerebral ischemia that happens with this procedure)
For carotid endarterectomies, use ______
Isoflurane
Protection, Ischemic
Isoflurane
Intracranial Pressure
Increases in ICP parallel increased ____ that is produced by anesthetics
_______ of lungs decreases PaCO2, therefore producing _______ and reducing tendency for increased ____
____ increases ICP ____ _____ volatile anesthetics (mostly because of the low dose it’s given in) (N2O safer than volatiles)
Avoid elevated ICP in _____ _____
CBF
Hyperventilation, Vasocontriction, ICP
N2O, Less Than
Head Injuries
Circulatory Effects
Mean Arterial Pressure
Agents ____, ____, ____, and ____ have dose dependent ____ on MAP due to decrease in the _____
______ decreases map due to decrease in cardiac ______
True circulatory affect of agents may not be reflected by BP since the BP may be elevated due to _____ stimulation elicited from surgery
Halo, Iso, Des, Sevo Decrease, SVR
Halothane, Contractility
SNS
Circulatory Effects
Heart Rate
Agents that increase HR are ____, ____, and ____
Confounding Variables: increased HR with ____ only with ______
Increased HR may also be due to _____ or _____ activity
______ may disrupt baroreceptor reflex and decrease ______ system of the heart
_____ affect on HR not determinable (it’s always given with other drugs)
Iso, Des, Sevo
Sevo, > 1.5 MAC
Opioids, SNS
Halothane, Conduction
N2O
Cardiac Output/Stroke Volume
______ has dose dependent decrease in _____ ______
____ and ____ have no effect on CO/SV
________ decreases CO up to _____, but when ______, CO recovers
Left SV _____ with all anesthetics
____ increases CO slightly
Halothane, Cardiac Output
Iso, Des
Sevoflurane, 2 MAC, > 2 MAC
Decreases
N2O
Systemic Vascular Resistance
Decreased SVR reflects increased ______ ______ and ______ blood flow (patient may appear flushed), which results from excess ______ relative to O2 needs
Decreased SVR also reflects loss of ____ ____, with enhanced drug delivery to the ______ ______
_______ dilates ONLY _____ and _____ vessels
Skeletal Muscle, Cutaneous
Perfusion
Body Heat, Neuromuscular Junction
Halothane, Cerebral, Cutaneous
Pulmonary Vascular Resistance
Volatile anesthetics have ____ to ____ effect
____ increases PVR; exaggerated effect in those with ______ ______, ______, and patients with congenital _____ ______
Little to No
N2O, Pulmonary HTN, Neonates, Heart Disease
Cardiac Dysrhythmias
Anesthetics ______ the dose of ______ required to produce ______ dysrhythmias
Effect greatest with ______
Interference with _______ rate of cardiac impulses through conduction system of heart
Decrease, Epinephrine, Ventricular
Halothane
Transmission rate
Coronary Blood Flow
Volatile anesthetics cause coronary _____, mostly in vessels 20-200 um ( ______ vessels)
______ dilates small coronary vessels more than larger conductance vessels
____ is capable of causing a maldistrubution of blood flow from ______ to ______ areas. This is called _____ ______ _____
Ischemia has resulted in patients with CAD when ____ and ____ were used
Vasodilation, Small
Isoflurane
Iso, Ischemic, Non ischemic
Coronary Steal Sydrome
N2O and Isoflurane
Coronary Blood Flow
No increased risk of acute ___ with volatile anesthetics as long as _______ are maintained
**May need to pretreat patients with _____ or a ____ _____
(If patient is already on beta blocker, ask if they took their dose the morning of surgery. If not, esmolol or similar agent may need ti be administered)
MI, Hemodynamics
Opioids, Beta Blocker
Neurocirculatory Response
______’s solubility make it a good choice to treat abrupt increases in systemic ___ and ____ associated with changes in intensity of _____ stimulation (This does NOT occur with Sevo)
Pre-existing _____ may influence the significance of ______ effects produced by inhaled anesthetics
A decrease in ______ associated with anesthetics is significant if there is diseased or ______ cardiac muscle
Neurocirculatory responses are a concern for patients with ____
Desflurane
BP, HR, Surgical
Disease, Circulatory
Contractility, Failing
CAD
Mechanism of Circulatory Effects
Direct myocardial _______
Inhibition of ____ _____ outflow
Peripherla autonomic _____ blockage
Attenuation of _____ _____ reflex activity
Decreased formation of ____, Decreased release of ______, Decreased influx of ____ ion
Depression
CNS Sympathetic
Ganglion
Carotid Sinus
cAMP, Catecholamines, Ca++
All volatiles produce dose dependent _____ in BP
_____ produces the most profound _____ in SVR
_____ does NOT cause decrease in BP when administered _____
Decrease
Isoflurane, Decrease
Nitrous, Alone
Heart Rate
HR increases the most with the use of ____, closely followed by ____
____, ____, and ____ produce coronary vasodilation
_____ causes least amount of coronary vasodilation
______ is the most _____ of the volatile anesthetics, and is also a potent coronary _______
Des, Iso
Iso, Des, Sevo
Sevo
Isoflurane, Potent, Vasodilator
Cardiac Preconditioning
Can use concentrations of Isoflurane as low as ______
May protect against ______ ______ and _____ ______ injury
APC limits infarct ____
___ ______ elevation decreases
______ production decreases
0.25 MAC
Prolonged Ischemia, Reperfusion Injury
Size
ST Segment
Lactate
Possible mechanisms of Cardiac Preconditioning
Release of ______ (a vasodilator substance) that binds to adenosine receptors A1 and A2
Binding to A2 receptors: increased ____ leads to stimulation of ___ channels, leading to ________, causing relaxation of vascular _____ _____
Binding to A1 receptors: decreased ____ leads to inhibition of ___ entry, causing a decreased _____ _____ of the ___ _____
Adenosine
cAMP, K+, Hyperpolarization, Smooth Muscle
cAMP, Ca++, Action Potential, SA Node
Possible mechanisms of Cardiac Preconditioning
Opening of ___ channels is critical for beneficial cardioprotective effects of IPC
K+ channels can be closed by ______, abolishing anesthetic preconditioning (Should be discontinued 24-48 hours prior and administer sliding scale ____)
_______ also antagonizes the function of K+ channels
K+
Sulfonylureas, Insulin
Ketamine
Possible mechanisms of Cardiac Preconditioning
_____ and _____ may mimic IPC
______ antagonizes APC, use in caution in patients at risk for _______ ____
Adenosine, Opioids
Ketamine, Perioperative MI
Pulmonary Effects
Inhaled anesthetics cause a dose dependent _____ in frequency of breathing
_____ _____ decreases with increased _______ (rapid and shallow breathing pattern)
This causes decreased ______ ______ and increased _____, leading to _______ ______
Increase
Tidal Volume, Frequency
Minute Ventilation, PaCO2
Respiratory Acidosis
Pulmonary Effects
Inhaled agents cause dose dependent ______ in ______ evidenced by decreased ventilatory response to CO2 and _____ in PaCO2
_____ may accentuate increased _____ production
Mechanism of depression pertains to depressant effects on the ______ _____ ______
Depression, Ventilation
Increases
COPD, PaCO2
Medullary Ventilatory Center
Pulmonary Effects
Anesthetics produce decreased ______ ______
Nitrous causes an ______ incident of pulmonary vascular resistance, but ______ agents cause a decrease in PVR (except Des)
Airway Resistance
Increased, Volatile
Hypoxic Pulmonary Vasocontriction
Ability of pulmonary vasculature to ______ in response to _______
Results in more optimal ______ to ______ match
Volatile agents mildly _____ the HPV mechnism
Read Flood, Page 599
Hepatic Effects
Anesthetics may interfere with _____ due to decreased ______ blood flow or inhibition of _______
Inhibition may be _______ specific; more important than ______ in blood flow
Transient ______ in LFT’s (surgical stimulation increases all LFTs
Increase in _____ with ______ and ______, none with ______
Clearance, Hepatic, Enzymes
Enzyme, Decrease
Increase
ALT, Enflurane, Des, None with Iso
Hepatic Effects
Anesthetics produce mild _____ _____ due to inadequate hepatic ______
Metabolism of anesthetic agent can result in _____ liver protein which can produce a _____ ______ response
Potential for hepatic ______, is _______ proportional to the degree of ______
Hepatic Dysfunction
Acetylated
Severe Antibody
Injury, Directly, Metabolism
Hepatic Effects
____ is NOT metabolized to _____ _____, so no antibody production to _____ liver proteins can occur
_____ can be degraded by CO2 absorbents to produce _______, which is hepatotoxic in animals, but the concentration in the breathing circuit is ______ toxic levels
Sevo, Acetyl Halide, Acetylated
Sevo, Compound A, Below
Renal Effects
Anesthetics cause ______ renal blood flow, decreased ____, and decreased _____ _____, which is most likely related to the effects that anesthetic agents have on ____ and ____
Preoperative _______ helps prevent this
Decreased, GFR, Urine Output
BP and CO
Hydration (IV Fluids)
Renal Effects
*Fluoride Induced Nephrotoxicity*
Observed with ________, which is highly metabolized to ______ _____, which is a renal toxin
Current volatile anesthetics have decreased solubility, so most are _____ and never metabolize into _____ ______
Toxicity may include _____, ______, _______, increased serum _____, and the inability to concentrate ______ (think dehydration symptoms)
Methoxyflurane, Inorganic Fluoride
Exhaled, Inorganic Fluoride
Polyuria, Hyper Na+, Hyperosomlarity, Creatinine, Urine
Renal Effects
_____ is metabolized to ______ ______, which doesn’t impair renal function in patient’s without pre-existing ______ ______
_____ has greater _______ metabolism of inorganic fluoride
______ has greater ______ metabolism of inorganic fluoride
Sevo, Inorganic Fluoride
Renal Disease
Enflurane, Intrarenal
Sevoflurane, Hepatic
Renal Effects
*Vinyl Halide Nephrotoxicity*
CO2 absorbents such as ______ or _____ _____, react with ______ to form breakdown product known as ________, a vinyl ether
Need to use at least ______ fresh gas flow rate with Sevo to minimize concentration of ______ that may accumulate in the breathing circuit
Baralyme, Soda Lime, Sevo
Compound A
2L/Minute, Compound A
Skeletal Muscle Effects
Skeletal muscle ______ produced with most _____-derived anesthetics, but not with ______ or _____
_____ derivates can cause dose dependent _______ of NM blockers
Relaxation, Ether
Halothane, N2O
Ether, Enhancement
Skeletal Muscle Effects
Malignant Hyperthermia
______ susceptible patients
______ is the most potent trigger
Genetically
Halothane
Malignant Hyperthermia
Can develop _____ or _____ GA
Volatile anesthetics and ________ cause an increase in _______ ___ concentration in susceptible patient, resulting in persistent _____ contraction
________ state with increased ___ and unexplained increase in _____
Will also see ______, ______, _____, and ____
Rise in temperature is a _____ sign
During, After
Succinylcholine, Sarcoplasmic Ca++
Muscle
Hypermetabolic, HR, ETCO2
Acidosis, Rhabdo, Arrythmias, Hyper K+
Late
Malignant Hyperthermia
Unexplained increase in _____ (most sensitive indicator in the OR)
_____ _____ fever
Skeletal _____ rigidity
Lactic ______ (hyper metabolism)
Constant leak of SR ____ through defective ______ receptor
ETCO2
High Grade
Muscle
Acidosis
Ca++, Ryanodine
Malignant Hyperthermia
Must use ____ ____ anesthesia for these patients
Notify _____ immediately, _____ triggering agents, ______ with 100% O2 (with ____, not anesthesia circuit)
____ procedure
IV ______ (prevents release of Ca++ from the SR)
Give _____, Cool patient, _____ and _____ for Hyper K+, Monitor _____ output to watch for _____ to kidneys or _____
Total IV
Surgeon, Stop, Hyperventilate, TANK
Abort
Dantrolene
Bicarb, Insulin and D50, Urinary, Shock, ATN
Obstetric Effects
Dose dependent ______ in _____ smooth muscle contraction and blood flow
Relaxation is beneficial and may help remove retained _____, but may also contribute to blood loss in _____ ______
Anesthetics rapidly enter _____, but are rapidly _____
Decrease, Uterine
Placenta, Uterine Atony
Fetus, Exhaled
Resistance to Infection
Normal functions of the immune system may be _____ after anesthesia and surgery
Causes decreased ____ _____; affecting influenza and measles viruses
Inhaled anesthetics do not have ______ effects, but the liquid form of volatile anesthetics may be ______
Decreased
DNA Synthesis
Bateriostatic, Bactericidal
Metabolism
Metabolites may be toxic to ____, _____, or ______ organs (always check a _______ test in women of child bearing age)
Degree of metabolism may be influenced by rate of decrease of PA at end of anesthesia case
Assess magnitude of metabolism by measuring ______ or a comparison of total amount recovered in exhaled gases with amount taken up during administration (_____ _____)
Kidney, Liver, Reproductive, Pregnancy
Metabolites, Mass Balance
Metabolism of Volatile Agents
Metabolism is affected by what four main factors?
Chemical structure, Enzyme activity, Blood concentration, Genetic factors
Metabolism
N2O
Very _____ metabolism, mainly by ______ bacteria in the GI tract
An O2 concentration of _____ than ____ inhibits metabolism of N2O
Little, Anaerobic
Greater, 10%
Metabolism
Halothane
15-20% metabolized by _______ enzymes
Oxidative metabolism produces ______ _____ that may acetylate hepatic proteins resulting in formation of _______
Reductive metabolism in hepatocyte hypoxia produces _____ _____
Cytochrome P-450 Enzymes
Trifluoroacetyl Halide, Antibodies
Inorganic Fluoride
Metabolism
Enflurane
3% metabolized by _______ enzymes
Oxidative metabolism may produce _______ hepatic ______ complexes
Low _____ in tissues
_______ increases nephrotoxic potential
Cytochrome P-450
Fluoroacetylated, Protein-Ab
Solubility
Isoniazid
Metabolism
Isoflurane
0.2% metabolized by ______ enzymes
Oxidative metabolism to _______ ____, possibility of producing acetylated hepatic ______ complexes
Low ______
Concentration of inorganic flouride produced is less than with _____
Cytochrome P-450
Trifluoroacetric acid, Protein-Ab
Solubility
Enflurane
Metabolism
Desflurane
0.02% metabolized by _______ enzymes
Oxidative metabolism to _______ _____, possibility of producing acetylated hepatic ______ complexes
Low ______
Cytochrome P-450
Trifluoroacetic acid, Protein-Ab
Solubility
Metabolism
Sevoflurane
5% metabolozed by _______ enzymes
Oxidative metabolism does NOT produce _____ _____, therefore, there is no possibility of hepatic _______ complexes
Degraded by CO2 ______ to potentially nephrotoxic _______, which is more likely to happen with _______
Renal exposure to flouride concentration is not concerning because most ______ is through the lungs
Cytochrome P-450
Acetyl Halides, Protein-Ab
Absorbents, Compound A, Baralyme
Elimination
Carbon Monoxide Toxicity
CO formation is a product of _____ of anethetics
_____, followed by _____, have the highest production of CO
_____ and _____ have no _____ group, therefore, they do not produce CO
CO toxicity increases intraoperative _______ concentration
____ detection difficult since oximeter can’t detect Carboxy-Hgb versus Oxy-Hgb
CO toxicity may produce delayed ________ effects (cognitive effects), ______ changes, _____ distrubance - can occur 3-21 days later
Degradation
Desflurane, Enflurane
Halothane, Sevoflurane
Carboxyhemoglobin
CO
Neurophysiological
Metabolism
(Factors that increase magnitude of CO production)
Dryness of ___ ______ - Prevented by ______
High ______ of absorbent - occurs during _____ fresh gas flows or increased metabolic production of ____
Prolonged ____ fresh gas flows (contribute to _____ of absorbent)
______ absorbent predispositioned to CO production more than ______ absorbent
CO2 Absorbent, Hydration
Temperature, Low, CO2
High, Dryness
Baralyme, Soda Lime
CO2 Absorber Fires
______ reacts with dessicated CO2 absorbents to produce CO and ______ organic compounds such as ______ or _______
This reaction produces _____, which increases chemical reaction _____ so that _____ breaks down rapidly
_______ metabolites can spontaneously ______ at high temperatures
Most often associated with ______
Sevoflurane, Flammable, Methanol, Formaldehyde
Heat, Speed, Sevoflurane
Flammable, Combust
Baralyme
Minimal Alveolar Concentration
Each gas has a different _____
A _____ (or 1 MAC) is the % of anesthetic agent (gas) which ceases movement in response to noxious stimuli in _____ of patients
An increase to a MAC of ____ will prevent movement in _____ of patients
See Table 4.6 in Stoelting Book
MAC is _____ in women with natural red hair due to mutations of the _______ receptor gene
MAC
MAC, 50%
1.3, ~95%
Increased, Melano-cortin-1
MAC
MAC _____ : opposite of MAC
MAC Awake is where ____ of patients will respond appropriately to verbal command and stimuli
Nitrous (About 60%) will decrease the MAC by ____ (roughly)
______ of a MAC should produce MAC Awake for volatiles
Awake
50%
1/3
1/10
Xenon (Inert Gas)
MAC is gender dependent, being less in ______
Non-explosive, Not pungent, minimal ______ depression
Main issue is the high _____ & needs more studies to prove ______
Lowest blood:gas coefficient of ______
Does have a tendency to _____, like N2O
Does not contribute to ______ ______
Emergence is _____ faster than nitrous or Sevo
Females
Cardiac
Cost, Morbidity
0.115
Bubble
Malignant Hyperthermia
2-3 x
