Term
| Inhalants have been used for over ___ years. |
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Definition
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Term
| What is the oldest inhalation anesthetics? Youngest? |
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Definition
-Nitrou Oxide
-Sevoflurane |
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Term
| What is the significance of Bromine and Chlorine groups on organic inhalation anesthetics? |
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Definition
| -more Br or Cl means more soluble and thus more potent |
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Term
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Definition
| -the pressure that a molecule exerts while changing from a liquid to a gas |
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Term
| In which conditions does vapor pressure reach equilibrium? |
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Definition
| -in a closed container at constant temp |
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Term
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Definition
| -temp at which the vapor pressure of liquid is equal to the ATM |
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Term
| As altitude increases, boiling point (decreases/increases). |
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Definition
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Term
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Definition
| -an agent that exists in its gaseous form at roomp temp and at sea level pressure |
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Term
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Definition
| -a gaseous state of a substance that at ambient temp and pressure is a liquid |
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Term
| What is the major difference between administration of a gas and a vapor? |
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Definition
| -gas can be administered from 0-100% while a vapor has a ceiling that is dictated by its vapor pressure |
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Term
| What is the major difference i admin of IV drugs and that of inhalants? |
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Definition
| -inhalant delivery depends on uptake by blood from within the lungs followed by delivery to the CNS |
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Term
| Inhalants that have a higher blood:gas partition coefficient take a (longer/shorter) time to reach equilibrium between the amount inhaled and exhaled due to the (greater/lower) uptake into the blood and tissues. |
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Definition
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Term
| How is the solubility coefficient expressed? |
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Definition
| -as the partition coefficient |
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Term
| What is the blood/gas partition coefficient? |
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Definition
| -the means for predicting speed of anethetic induction, recovery, change in depth of anesthesia |
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Term
| Does a low blood/gas partition coefficient indicative of a fast or slow change in depth of anesthesia? What about a high one? |
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Definition
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Term
| True or False: The oil/gas partition coefficient is in direct correlation with anesthetic potency. |
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Definition
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Term
| The higher the tissue solubility, the (longer/shorter) it will take to saturate. |
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Definition
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Term
Order the following anesthetic agents from highest to lowest blood:gas coefficient:
isoflurane, desflurane, halothane, nitrous oxide, sevoflurane |
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Definition
| haltohane > isoflurane > sevoflurane > desflurane > nitrous oxide |
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Term
| How are inhalaltion anesthetics similar to gases of respiration? |
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Definition
| -move down series of partial pressure gradients, areas of higher tension to lower tension, until equilibrium is established |
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Term
| What makes the following statement true: "By knowing and controlling the alveolar pressure in essence the brain partial pressure is controlled as well" |
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Definition
| -the arterial pressure is very close to the alveolar pressure and hte brain partial pressure closely follows alveolar |
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Term
| What two major factors are related to rapid changes in alveolar anesthetic tension? |
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Definition
1. inc alveolar delivery: inc inspired anesthetic concentration & inc alveolar ventilation
2. dec removal from the alveoli |
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Term
| Why does in inspired anesthetic concentration inc the alveolar delivery? |
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Definition
| - inc vaporization of agent, inc vaporizer setting, inc fresh gas flow, dec gas volume of patient breathing system |
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Term
| How does inc alveolar ventilation lead to inc alveolar delivery? |
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Definition
-inc MV
-dec dead space ventilation |
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Term
| How does dec removal fro mthe alveoli lead to rapid changes in alveolar anesthetic tension? |
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Definition
-dec blood solubility of anesthetic
-dec CO
-dec alveolar-venous gradient |
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Term
| What is the second gas effect? |
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Definition
| -when adding in N2O the rate in rise of Halothane is increased during the arly admin (used to speed up anesthetic induction) |
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Term
| Is an inc or dec in CO associated with inc in the rate of induction? Why? |
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Definition
| -dec b/c causes an increase in alveolar concentration of anesthetic |
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Term
| What part of the body uses the most of CO? |
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Definition
| -brain, liver, and kidneys |
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Term
| The same 3 factors that account for induction account for recovery. what are they? |
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Definition
-solubility
-CO
-alveolar to venous partial pressure difference |
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Term
| What causes diffusion hypoxia? |
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Definition
| -when a patient on N2O breaths room air immediately rather than inc FiO2, a large volume of N2O will diffuse out of the blood into the alveoli and will displace all other gases (such as oxygen) within the lung, thus will cause dec tensions in the arterial oxygenation and lead to hypoxia |
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Term
| Where is the majority of anesthetic biotransformed? |
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Definition
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Term
| Definition: Minimum alveolar concentration (MAC) |
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Definition
-the minimum alveolar concentrationf of anesthetic at 1 atmosphere that produces immobility in 50% of the population exposed to a supramaximal noxious stimulus
-corresponds to the ED 50 |
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Term
| Is anesthetic potency directly or inversely proportional to the MAC? |
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Definition
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Term
| What can cause decreses in MAC? |
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Definition
-hypothermia
-hyponatremia
-severe hypotension < 50 mmHg
-advanced age
PaO2 < 40 mmHg
-PaCO2 > 95 mmHg
-pregnancy
-drugs: ketamine, lidocaine, thiopental, ace, benzo, alpha-2, merperidine, opioids, etc |
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Term
| What can cause increases in MAC? |
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Definition
-hyperthermia
-hyperthyroidism
-young animals: high metabolism
-drugs: meth, cocaine, morphine, etc |
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Term
| True or False: Duration of anesthesia and metabolic acid/base can have large effects on MAC. |
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Definition
| -FALSE, neither affect MAC |
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Term
| Inhalants are generally more promiscuous in their molecular targets. While the receptors they affect are inhibitory, they are numerous. Can you name a few? |
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Definition
-GABA rc
-Glycine Rc
-5-HT3 rc
-AMPA rc
-NMDA rc
-Na chh
-Ca chh
-Background K chh |
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Term
| Which parts of the CNS are targeted to induce unconsciousness? |
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Definition
| -cortex, thalamus, brainstem |
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Term
| What parts of the CNS are targeted to induce amnesia? |
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Definition
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Term
| What part of the CNS is targeted to induce immobility? |
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Definition
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Term
| What part of the CNS is targeted to induce anagesia? |
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Definition
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Term
| What is the significance of a MAC of 0.8-1.0? |
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Definition
| -can decrease but don't abate wind-up and central sensitization and can help prevent heightened post-op pain sensitivity |
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Term
| What is the significance of a MAC of 0.4-0.8? |
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Definition
| -decrease withdrawal response to noxious stimulus, but lower concentrations can actually cause hyperalgesia with a peak effect at 0.1 times MAC due to potent nicotinic, cholinergic receptro inhibition |
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Term
| What are the non-anesthetic effects of inhalation anesthetics on the respiratory system? |
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Definition
-blunt hypoxicc and hypercapnic ventilatory response
-hypoxic suppression can occur for several hourse after cessation of anesthesia
-wakness of repsiratory muscles
-bronchodilation: block the voltage gated Ca chh to relax airway smooth msucle |
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Term
| What non-aensthetic effects does halothane specifically have? |
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Definition
-dramatic suppression of ventilatory response
-can produce reactive oxygen species |
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Term
| What non-anesthetic effects does Desflurane specifically have on the respiratory system? |
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Definition
| -minimal respiratory effects except in equine |
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Term
| What non-anesthetic effect does Isoflurane have on the respiratory system? |
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Definition
| -moderate inhibition of ventilatory response |
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Term
| How do we avoid suppression of hte respiratory response by halothane and isoflurane? |
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Definition
| -pretreatment with antioxidants |
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Term
| What are the 4 factors primarily influencing the respiratory effects of inhalation anesthetics? |
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Definition
-mode of ventilation
-duration of anesthesia
-surgery and other noxious stimulation
-concurrent drugs |
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Term
| What are some of the CV effects of inhalation anesthetics?/ |
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Definition
-dose dependent myocardial depression
-alterations in Ca+ entry and SR function
-negative inotrope with subsequent dec in SVR
-prolong the QT interval
-inc HR
-adrenergic agonsit associated dysrhytmias exaggerated
-reduce overall blood flow |
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Term
| Which inhaled anesthetic is the worst at overall dec in CO? |
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Definition
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Term
| True or False: All horses need ionotropic support at some point. |
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Definition
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Term
| LOOK AT THE CHART ON SLIDE 31 OF INHALATION ANESTHETICS PP!!! |
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Definition
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Term
| What are the 5 factors that influence the circulatory effects on inhalation anesthetics? |
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Definition
-anesthetic dose
-mode of ventilation: inc PaCO2 = heart/SM depression
-noxious stimulus: modifies the circulatory effect via stim of SNS
-duration of anesthesia
-concurrent drugs |
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Term
| What effects do inhaled anesthetics have on cerebral metabolism? |
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Definition
| -dec and thus dec oxygen consumption |
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Term
| How do inhaled anesthetics affect cerebral blood flow? |
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Definition
| -either no hcange or inc (vasodilation) |
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Term
Rank the following inhaled anesthetics from leas effects to most regarding cerebral blood flow and metabolism:
enflurane, desflurane, sevoflurane, halothane, isoflurane |
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Definition
| -sevoflurane < desflurane < isoflurane < enflurane < halothane |
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Term
| True of False: Cerebral vascular autoregulation, CBF, and ICP can be rpeserved at given MAC multiples anethetic when BP, CO2, and OR are maintained in the autoregulatory range. |
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Definition
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Term
| What are the 3 characteristic CNS changes for most anesthetics? |
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Definition
-larger amplitude and lower frequency
-burst suppression with isoelectric
-isoelectric activity |
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Term
| Inhaled anesthetics cause a/an (dec/inc) in overal ICP and this parallels the change in CBF. Any exceptions? |
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Definition
-inc
-except in horses or other LA |
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Term
| What non-anesthetic effects do inhaled anesthetics have on the kindeys? |
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Definition
-dose related dec in renal blood flow and GFR
-smaller V of = inc BUN, creatinine, and PO4
-rehydrate them |
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Term
| Which inhaled anesthetic was pulled form the market for causing nephrotoxicity? Why did this not apply to Sevoflurane? |
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Definition
-Methoxyflurane
-b/c Sevoflurane is not broken down inthe kidneys, it is broken down in the liver |
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Term
| How do inhaled anesthetic agents affect the liver? How is this clinically relevant? |
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Definition
-cause injury via reducing blood flow and O2 delivery
-depression of hepatic function and hepatocellular damage can occur
-causes reduction of intrinsic hepatic clearance of drugs |
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Term
| What are the 3 confounding factors that worsen or increase the likelihood of hepatic damage by inhaled anesthetics? |
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Definition
-use of nitrous oxide
-concurrent hypoxia
-mode of ventilation (PPV): positive pressure ventilation |
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Term
| Describe the two types of hepatotoxicity due to inhaled anesthetic agents. |
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Definition
-Type I: MOST COMMON; asymptomatic elevation in liver enzymes 1-2w after exposure, resolves by itself
-Type II: immune mediated response that leads to fulminant hepatitis and can be delayed up to one month after Sx |
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Term
| How do inhaled anesthetics affect skeletal muscle? |
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Definition
-dose-dependant relaxation: dec deplarizing current at NMJ in response to ACh, diect inh of nicotinic ACh rc, enhancement of spinal cords glycine rc
-potentiates effects of deplarizing and non-depolarizing muscle relaxants |
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Term
| Which type of inhaled inahlants can trigger Procine Stress Sydnrome? Seen in any other animals? What happens? |
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Definition
-all non-organic inhalants
-reports in horses and dogs too
-muscle rigidity, rhabdomyolysis, inc in BT, CO2 pdn, and O2 consumption |
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Term
| How do nitrous oxide and xenon provide analgesia? What effects do you see if it takes a wrong turn? |
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Definition
-inhibition of NMDA receptors
-can produce excitement and euphoria |
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Term
| What are the mutagenic and immunomodulatory effects of inhaled anesthetics? |
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Definition
-generally inhibit inflammatory cytokines
-reduce production of reactive oxygen species |
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Term
| What are the potential metabolic effects of N2O? |
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Definition
-can produce megaloblastic bone marrow changes
-precipitateneuro complications due to vit B12 deficiency |
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Term
| Benefits of halothane? Disadvantages? |
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Definition
-Advantages: not very pungent, compatible with inhalation induction, lower risk of nausea
-Disadvantages: sensitization of myocardium to catecholamine induced arrhythmias, severe hepatic necrosis pediatric patients can have severe cradyarrhythmias |
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Term
| What are the extra effects of sevoflurane? |
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Definition
-swett smelling
-metabolism can lead to relase of inorganic fluoride molecue
-can form CO when exposed to dehydrated CO2 absorbents that can ignite fire
-least amount of vasodilation |
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Term
| Which inhaled anesthetic is the agent of choice for neurosurgery and patients with inc ICP? |
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Definition
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Term
| What are the disadvantages of desflurane? |
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Definition
-inc symp tone at low doses
-can be associated with tachycardia and hypertension
-can be degraded to CO by certain dehydrated CO2 absorvents so always change absorbent after sue |
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Term
| What is the MAC of nitrous oxide in dogs? |
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Definition
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Term
| What are the disadvantages of Nitrous oxide in dogs? |
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Definition
-no skeletal muscle relaxation
-teratogenic effects
-gas transfer into closed spaces
-diffusion hypoxia
-dec myocardial function but inc BP and cardiac arrhythmias
-interferes with RBC and WBC pdn in bone marrow |
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Term
| How should nitrous oxide be used? |
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Definition
| -to speed up induction of other inhalants by utilizing the second gas effect |
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Term
| What is the MAC of xenon? Why do we not use it? |
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Definition
-71%
-high MAC and very, very expensive |
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Term
| When is air contamination with inhaled anesthetics a concern? |
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Definition
-vaporizer filling
-known and unknown leaks in the patient breathing circuit
-spillage of liquid agent
-disconnection of patient fron anesthetic circuit |
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Term
| How do we decrease contamination via inhaled anesthetic agents> |
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Definition
-use wast gas scavnger
-adequate ventilation
-be aware and educate
-monitor room for trace gas levels |
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