Anesthesia Systems & Vaporizers Overview
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Questions and Answers

Which of the following statements accurately describes nonprecision vaporizers?

  • They provide a pollution-free environment.
  • They are temperature compensated and easy to use.
  • They are difficult to monitor anesthetic concentration. (correct)
  • They are suitable for use with rebreathing systems.

    • What is a potential issue when using a nonprecision vaporizer with low oxygen flow rates?

  • Sufficient temperature compensation.
  • Increased efficiency of anesthetic uptake.
  • High risk of hypercarbia. (correct)
  • Decreased cost of anesthesia.

    • Which factor does NOT affect the output of vaporizers?

  • Anesthetic agent concentration.
  • Type of surgical procedure. (correct)
  • Oxygen flow rate.
  • Barometric pressure.

    • What is a disadvantage of using a nonprecision vaporizer in anesthesia?

    <p>It is hard to estimate anesthetic agent uptake.</p> Signup and view all the answers

    How can the removal of the wick in a vaporizer affect its operation?

    <p>It allows for the use of halothane or isoflurane.</p> Signup and view all the answers

    In a semiclosed system, what is a requirement concerning oxygen flow rates?

    <p>They need to exceed 2-3 mL/lb/min.</p> Signup and view all the answers

    What characteristic of unidirectional valves is true?

    <p>They help manage the direction of gas flow effectively.</p> Signup and view all the answers

    Which of the following is a possible effect of back pressure on a vaporizer?

    <p>Inconsistent output of anesthetics.</p> Signup and view all the answers

    Which of the following statements about the effects of D. α-2 Agonists is true?

    <p>They decrease salivation, which can be a concern for excessive saliva producers.</p> Signup and view all the answers

    What is one of the primary actions of acetylpromazine in veterinary medicine?

    <p>Provides sedation often for extended periods.</p> Signup and view all the answers

    Which adverse effect is associated with the use of acetylpromazine?

    <p>Abortion in cattle during the last trimester.</p> Signup and view all the answers

    Which characteristic is NOT associated with D. α-2 Agonists?

    <p>They facilitate renal vasodilation.</p> Signup and view all the answers

    What is an analgesic effect of acetylpromazine?

    <p>Enhances the effectiveness of opioids.</p> Signup and view all the answers

    In which situations should D. α-2 Agonists be avoided?

    <p>In horses and ruminants.</p> Signup and view all the answers

    How do D. α-2 Agonists primarily exert their effects?

    <p>By reducing the level of norepinephrine centrally and peripherally.</p> Signup and view all the answers

    What effect may occur in dogs as a result of D. α-2 Agonist use?

    <p>Cyanosis due to peripheral vasoconstriction.</p> Signup and view all the answers

    What is the primary goal of pharmacologic pain control in veterinary practice?

    <p>To ensure the patient sleeps and moves around comfortably</p> Signup and view all the answers

    Which method of analgesic delivery is least likely to be effective for providing preemptive analgesia?

    <p>Application of local anesthetics after pain onset</p> Signup and view all the answers

    Which of the following combinations represents a balanced analgesia protocol?

    <p>Opioids and NSAIDs</p> Signup and view all the answers

    What is the maximum dose of bupivacaine that can be safely administered to dogs?

    <p>2.0 mg/kg</p> Signup and view all the answers

    Which analgesic is considered effective for visceral pain?

    <p>Butorphanol</p> Signup and view all the answers

    What is a contraindication for administering epidural morphine?

    <p>Septicemia</p> Signup and view all the answers

    Which of the following statements about opioids is true?

    <p>They effectively manage sore or achy pain</p> Signup and view all the answers

    Which of the following methods is NOT a route of analgesic administration?

    <p>Intranasal</p> Signup and view all the answers

    What does an increase in ventilation primarily affect in terms of anesthetic dosing?

    <p>It will increase the alveolar concentration.</p> Signup and view all the answers

    Which statement correctly describes the relationship between MAC and brain partial pressure?

    <p>MAC reflects the brain partial pressure because the alveolar partial pressure is in equilibrium with the brain.</p> Signup and view all the answers

    What is the consequence of a decrease in ventilation during anesthesia?

    <p>It will lower the alveolar concentration of anesthetics.</p> Signup and view all the answers

    Which factor is LEAST likely to affect the rate of rise of the alveolar anesthetic concentration?

    <p>Tissue blood flow.</p> Signup and view all the answers

    What effect does solubility have on anesthetic uptake from the alveoli?

    <p>Lower solubility decreases the rate of blood uptake.</p> Signup and view all the answers

    What causes a positive feedback during circulatory depression in anesthesia?

    <p>Increased anesthetic concentration leads to further circulatory effects.</p> Signup and view all the answers

    In the context of inhaled anesthetics, which statement about the MAC is true?

    <p>Lower MAC indicates a higher potency of the anesthetic.</p> Signup and view all the answers

    How do combinations of inhaled anesthetics affect MAC?

    <p>They cause a synergistic effect reducing MAC overall.</p> Signup and view all the answers

    What is the primary characteristic of butorphanol regarding its cardiovascular effects?

    <p>It shows little cardiovascular depression.</p> Signup and view all the answers

    Which of the following statements about buprenorphine is true?

    <p>Its duration of action is clinically around 4 to 6 hours.</p> Signup and view all the answers

    What should be done when administering thiopental to hypoproteinemic animals?

    <p>Reduce the dose of thiopental.</p> Signup and view all the answers

    How long does butorphanol primarily act in animals?

    <p>1 to 2 hours.</p> Signup and view all the answers

    What is a notable side effect that can occur with butorphanol in certain cases?

    <p>Dysphoria.</p> Signup and view all the answers

    Which animal group may experience prolonged recovery due to thiopental's redistribution?

    <p>Sighthounds.</p> Signup and view all the answers

    What major clinical issue is addressed with the use of cyclohexamines such as ketamine?

    <p>They induce dissociative anesthesia or catalepsy.</p> Signup and view all the answers

    What should be considered when injecting an alkaline solution perivascularly?

    <p>Treat with saline, lidocaine, and steroids.</p> Signup and view all the answers

    What is an approximate size for a rebreathing or reservoir bag for a patient?

    <p>30 mL/lb</p> Signup and view all the answers

    What is the recommended oxygen flow rate for the Bain system to allow some rebreathing?

    <p>100 mL/lb/min</p> Signup and view all the answers

    Which of the following statements about CO2 absorption canisters is correct?

    <p>2 tidal volumes is the recommended volume for CO2 canisters.</p> Signup and view all the answers

    What is a characteristic feature of the universal or Mera 'F' system?

    <p>Coaxial configuration with inspiratory limb contained within expiratory.</p> Signup and view all the answers

    What can happen if the Inner limb of the Bain system disconnects?

    <p>Respiratory acidosis.</p> Signup and view all the answers

    What issue may occur if moisture causes the endotracheal tube to stick?

    <p>Patient could experience atelectasis.</p> Signup and view all the answers

    Which of the following statements about the length of the endotracheal tube outside the mouth is true?

    <p>Is considered mechanical dead space if too long.</p> Signup and view all the answers

    What is a potential risk of using a low oxygen flow rate in a Bain system?

    <p>Decreased CO2 removal efficiency.</p> Signup and view all the answers

    What is the primary reason for using three times the volume of a balanced electrolyte to replace blood loss?

    <p>Only a portion of the fluid remains in the vascular compartment.</p> Signup and view all the answers

    What could cause low tidal CO2 values during anesthesia?

    <p>Overzealous ventilation</p> Signup and view all the answers

    In terms of ECG use during anesthesia, which statement is true?

    <p>ECG is used to monitor the electrical rhythm of the heart.</p> Signup and view all the answers

    What is a primary action of acetylpromazine in veterinary medicine?

    <p>Decreases MAC</p> Signup and view all the answers

    What is a significant consequence of failing to return the tidal CO2 curve to baseline?

    <p>It signifies rebreathing.</p> Signup and view all the answers

    What initial physiological change is typically observed with α-2 Agonist administration?

    <p>Initial hypertension followed by hypotension</p> Signup and view all the answers

    Which side effect is associated with the use of acetylpromazine?

    <p>Vomiting in small animals</p> Signup and view all the answers

    What should be considered when using high-molecular-weight solutions like hetastarch for blood replacement?

    <p>A smaller volume is sufficient for replacement.</p> Signup and view all the answers

    Which statement accurately reflects a contraindication for the use of D. α-2 Agonists?

    <p>Should be avoided in patients with hypotension</p> Signup and view all the answers

    Which artifact can interfere with ECG readings during monitoring?

    <p>Movement of the patient</p> Signup and view all the answers

    What effect does the use of α-2 Agonists have on salivation?

    <p>Decreases salivation significantly</p> Signup and view all the answers

    How does the replacement of blood loss differ when using whole blood compared to a balanced electrolyte?

    <p>Whole blood requires a 1:1 replacement ratio.</p> Signup and view all the answers

    What is an indicator of hyperventilation during anesthesia based on CO2 levels?

    <p>Values below 40 mm Hg</p> Signup and view all the answers

    What adverse effect can be caused by high doses of acetylpromazine?

    <p>Hypotension</p> Signup and view all the answers

    Which neurotransmitter is primarily reduced by D. α-2 Agonists?

    <p>Norepinephrine</p> Signup and view all the answers

    Acetylpromazine is effective as an antiemetic when used before which type of medication?

    <p>Opioids</p> Signup and view all the answers

    What is the purpose of using preemptive analgesia in pain management?

    <p>To prevent the development of windup in the spinal cord</p> Signup and view all the answers

    Which two classes of analgesics are commonly combined for balanced analgesia?

    <p>Opioids and local anesthetics</p> Signup and view all the answers

    What is the maximum safe dosage of bupivacaine for dogs?

    <p>2 mg/kg</p> Signup and view all the answers

    Which delivery method is least effective for preemptive analgesia?

    <p>Post-operative oral medication</p> Signup and view all the answers

    What is the effect of opioids on different types of pain?

    <p>Effective against sore and achy pain but less so for sharp pain</p> Signup and view all the answers

    Which of the following is a contraindication for administering epidural morphine?

    <p>Septicemia</p> Signup and view all the answers

    Which local analgesic method involves the administration of a solution into a specific joint?

    <p>Intraarticular morphine</p> Signup and view all the answers

    What is the recommended dosage range for bupivacaine in cats?

    <p>0.5 to 1 mg/kg</p> Signup and view all the answers

    What is a notable characteristic of the function of oxygen cylinders?

    <p>A full oxygen cylinder contains pressure between 1900 to 2200 psi.</p> Signup and view all the answers

    Which statement correctly describes one of the disadvantages of circle anesthesia machines?

    <p>They often have difficulty in predicting inspired concentration at low gas flows.</p> Signup and view all the answers

    What is the purpose of the device present in newer anesthesia machines regarding nitrous oxide?

    <p>To shut off nitrous oxide if oxygen supply is interrupted.</p> Signup and view all the answers

    In the context of nitrous oxide use, what does diffusion hypoxia refer to?

    <p>The rapid outpouring of nitrous oxide into the alveoli upon cessation of use.</p> Signup and view all the answers

    What is the metabolic requirement for oxygen during anesthesia?

    <p>2 to 3 mL/lb/min (4 to 6 mL/kg/min).</p> Signup and view all the answers

    What color coding is typically used for oxygen cylinders in the United States?

    <p>Green</p> Signup and view all the answers

    Which characteristic is NOT a feature of nitrous oxide?

    <p>It is always used in a 1:1 ratio with oxygen.</p> Signup and view all the answers

    What potential issue arises from the complex structure of circle anesthesia machines?

    <p>They have challenges in maintenance and cleaning.</p> Signup and view all the answers

    What is the normal heart rate range for cats during anesthesia?

    <p>180 to 200 beats/min</p> Signup and view all the answers

    What physiological effect occurs as a result of the second gas effect in anesthesia?

    <p>Enhanced uptake of concomitantly inhaled gases</p> Signup and view all the answers

    What is the character of hyperventilation according to arterial blood gas levels?

    <p>PaCO2 level is lower than 40 mm Hg</p> Signup and view all the answers

    Which monitoring method can be used to assess pulse strength during anesthesia?

    <p>Using an esophageal stethoscope</p> Signup and view all the answers

    Which term describes a fast breathing rate in anesthesia monitoring?

    <p>Tachypnea</p> Signup and view all the answers

    What is the acceptable heart rate range prior to surgery for cats if color, jaw tone, and pulse are acceptable?

    <p>80 to 90 beats/min</p> Signup and view all the answers

    Which of the following locations is NOT a common site to palpate for a superficial pulse?

    <p>Jugular vein</p> Signup and view all the answers

    What is the significance of a PaCO2 level higher than 40 mm Hg during anesthesia?

    <p>Indicates hypoventilation</p> Signup and view all the answers

    What is the primary function of a rebreathing or reservoir bag in anesthesia?

    <p>To assist in the prevention of atelectasis</p> Signup and view all the answers

    Which characteristic of the Bain system is most beneficial for small patients?

    <p>It minimizes resistance to breathing</p> Signup and view all the answers

    What occurs if the inner limb of the Bain system becomes disconnected?

    <p>Potential for hypoxia and respiratory acidosis</p> Signup and view all the answers

    How should the oxygen flow rate be adjusted to minimize rebreathing in a Bain system?

    <p>Use a flow rate of approximately 3 times the minute ventilation</p> Signup and view all the answers

    What role does the CO2 absorption canister play in an anesthesia machine?

    <p>It helps to eliminate carbon dioxide during respiration</p> Signup and view all the answers

    What material composition is typical of soda lime used in CO2 absorption?

    <p>94% calcium hydroxide, 5% sodium hydroxide, and 1% potassium hydroxide</p> Signup and view all the answers

    What is a significant risk associated with the endotracheal tube length being outside the mouth?

    <p>Increased mechanical dead space</p> Signup and view all the answers

    Which factor is most likely to contribute to endotracheal tube sticking during use?

    <p>Presence of moisture in the tube</p> Signup and view all the answers

    What is a disadvantage of using a circle anesthesia machine?

    <p>It is composed of many parts, leading to greater maintenance.</p> Signup and view all the answers

    Which characteristic is true about nitrous oxide (N2O) usage?

    <p>The second gas effect enhances the efficacy of other anesthetics.</p> Signup and view all the answers

    What happens during diffusion hypoxia when a patient is removed from nitrous oxide anesthesia?

    <p>Nitrous oxide rapidly exits the body, leading to oxygen dilution.</p> Signup and view all the answers

    What is the full pressure range of an oxygen cylinder when full?

    <p>1900 to 2200 psi</p> Signup and view all the answers

    What safety feature do newer anesthesia machines have regarding nitrous oxide?

    <p>Nitrous is automatically shut off if oxygen supply fails.</p> Signup and view all the answers

    What is a critical mistake to avoid when using a low oxygen flow rate in a Bain system?

    <p>Allowing the patient to breathe room air too early.</p> Signup and view all the answers

    Which of the following statements about oxygen cylinders is incorrect?

    <p>Oxygen is always compressed to a pressure of 700 psi.</p> Signup and view all the answers

    What is the metabolic requirement for oxygen during anesthesia?

    <p>2 to 3 mL/lb/min</p> Signup and view all the answers

    What is the appropriate dose of dexmedetomidine for intravenous administration in dogs?

    <p>0.5 mcg/lb (1 mcg/kg)</p> Signup and view all the answers

    Which of the following is NOT recommended for treating hypotension due to dexmedetomidine overdose?

    <p>Vasopressors like epinephrine</p> Signup and view all the answers

    What is a potential side effect of using dexmedetomidine in dogs?

    <p>Splenic enlargement</p> Signup and view all the answers

    Which drug can be used to reverse the effects of medetomidine?

    <p>Yohimbine</p> Signup and view all the answers

    What is a known characteristic of midazolam compared to diazepam?

    <p>Water soluble and better for IM injections</p> Signup and view all the answers

    Which side effect can be caused by opioids such as morphine in animals?

    <p>Bradycardia</p> Signup and view all the answers

    What effect does diazepam have as an anticonvulsant in animals?

    <p>It is sometimes ineffective</p> Signup and view all the answers

    Which reflex is used primarily in cats during anesthesia?

    <p>Ear-flick reflex</p> Signup and view all the answers

    What type of pain is characterized by its abrupt onset and short duration?

    <p>Acute pain</p> Signup and view all the answers

    What effect can happen due to the administration of high doses of opioids?

    <p>Respiratory depression</p> Signup and view all the answers

    Which reflex is NOT typically present during inhalation anesthesia?

    <p>Pedal reflex</p> Signup and view all the answers

    What type of pain results from physical damage to a nerve?

    <p>Neuropathic pain</p> Signup and view all the answers

    Which reflex can be used to assess the depth of anesthesia but is considered not reliable?

    <p>Ear-flick reflex</p> Signup and view all the answers

    What kind of pain is described as well-localized and typically sharp?

    <p>Somatic pain</p> Signup and view all the answers

    Which term refers to pain that is felt in a different part of the body from where it originated?

    <p>Referred pain</p> Signup and view all the answers

    What is the main function of nociceptors?

    <p>To detect noxious stimuli</p> Signup and view all the answers

    What is the approximate recommended size for a rebreathing or reservoir bag for an animal?

    <p>30 mL/lb</p> Signup and view all the answers

    Which characteristic of the Bain system makes it suitable for small patients?

    <p>Absence of dead space</p> Signup and view all the answers

    What is the effect of disconnecting the inner limb of the Bain system?

    <p>Respiratory acidosis</p> Signup and view all the answers

    Which formulation of CO2 absorption canisters does NOT contain barium hydroxide?

    <p>Soda lime</p> Signup and view all the answers

    What is a consequence of having too low of an oxygen flow in a Bain system?

    <p>Enhanced rebreathing</p> Signup and view all the answers

    What is the primary purpose of the rebreathing or reservoir bag?

    <p>To act as a reservoir for exhaled gases</p> Signup and view all the answers

    What is the purpose of using a flow rate of 100 mL/lb/min in a Bain system?

    <p>To allow some rebreathing</p> Signup and view all the answers

    What could potentially cause the endotracheal tube to stick during use?

    <p>Excessive humidity</p> Signup and view all the answers

    What heart rate range is acceptable for cats prior to surgery if certain physiological signs are acceptable?

    <p>80 to 90 beats/min</p> Signup and view all the answers

    What is the high range for a normal heart rate in dogs during anesthesia?

    <p>150 to 160 beats/min</p> Signup and view all the answers

    What happens when the pressure in a cylinder exceeds 200 psi?

    <p>The pressure regulator will reduce it to 50 psi.</p> Signup and view all the answers

    In the context of tachypnea, what does this term indicate regarding breathing rate?

    <p>Rapid breathing rate</p> Signup and view all the answers

    What is the purpose of a vaporizer in anesthesia delivery?

    <p>To convert liquid anesthetic to a vapor state.</p> Signup and view all the answers

    What physiological effect does nitrous oxide (N2O) have when rapidly uptaken during anesthesia?

    <p>It decreases available oxygen.</p> Signup and view all the answers

    Which factor is critical for flow meters to function properly?

    <p>Gas flow must exceed 30% of total flow for nitrous oxide.</p> Signup and view all the answers

    What does the abnormal PaCO2 level indicate in the context of hypoventilation?

    <p>Greater than 40 mm Hg</p> Signup and view all the answers

    During anesthesia, which of the following heart rate ranges is considered normal for horses?

    <p>26 to 40 beats/min</p> Signup and view all the answers

    What is the minimum alveolar concentration (MAC) range for achieving moderate anesthesia?

    <p>1.3 to 1.5%</p> Signup and view all the answers

    What is a notable side effect of D. α-2 Agonists affecting salivation in animals?

    <p>Decreased saliva production</p> Signup and view all the answers

    Which of the following describes a cardiovascular effect associated with D. α-2 Agonists?

    <p>Initial hypertension followed by hypotension</p> Signup and view all the answers

    What does the pressure regulator do when attached to the anesthesia machine?

    <p>It reduces the cylinder pressure to a safe level.</p> Signup and view all the answers

    What is an indicator that the pulse strength is appropriate?

    <p>Strength correlating with pulse pressure</p> Signup and view all the answers

    What is one of the primary actions of acetylpromazine in veterinary medicine?

    <p>Provides sedation</p> Signup and view all the answers

    What happens to alveoli during nitrous oxide uptake in relation to other gases?

    <p>Contraction of the alveoli</p> Signup and view all the answers

    Which characteristic is typically associated with precision vaporizers?

    <p>They adjust automatically for temperature fluctuations.</p> Signup and view all the answers

    When should an oxygen cylinder be replaced?

    <p>If less than 200 psi remains in the cylinder.</p> Signup and view all the answers

    Which side effect is most commonly associated with large doses of acetylpromazine?

    <p>Hypotension</p> Signup and view all the answers

    What potential adverse effect can result from using excessive doses of acetylpromazine?

    <p>Respiratory depression in some dogs</p> Signup and view all the answers

    What is a common misconception about the handling of oxygen tanks?

    <p>It is acceptable to tip them over during use.</p> Signup and view all the answers

    In which type of animals are D. α-2 Agonists likely to be contraindicated?

    <p>Equines and ruminants</p> Signup and view all the answers

    What is a potential adverse effect of the antihistamine effect of acetylpromazine?

    <p>Decreased seizure thresholds</p> Signup and view all the answers

    What mechanism do D. α-2 Agonists primarily use to exert their pharmacological effects?

    <p>Reducing norepinephrine levels</p> Signup and view all the answers

    Which reflex is not typically present during inhalation anesthesia?

    <p>Pedal reflex</p> Signup and view all the answers

    Which type of pain is characterized by a sudden onset and brief duration?

    <p>Acute pain</p> Signup and view all the answers

    What is the primary characteristic of nociceptors?

    <p>Nerve endings sensitive to noxious stimuli</p> Signup and view all the answers

    Which reflex is used primarily in cats to assess anesthesia depth?

    <p>Ear-flick reflex</p> Signup and view all the answers

    What is hyperesthesia?

    <p>Increased sensitivity to stimuli</p> Signup and view all the answers

    How is referred pain best explained?

    <p>Pain perceived in an area other than the source</p> Signup and view all the answers

    Which of the following statements about nociception is accurate?

    <p>It includes the reception and central processing of pain signals.</p> Signup and view all the answers

    Which statement about preemptive analgesia is correct?

    <p>It is meant to create analgesia before the occurrence of pain.</p> Signup and view all the answers

    Study Notes

    Vaporizers

    • Ohio no. 8 (ether 8) is historically used with methoxyflurane
    • Most vaporizers are rarely used
    • Factors that affect the output of vaporizers:
      • Temperature
      • Carrier gas flow rate
      • Barometric pressure
      • Back pressure

    Anesthesia Systems

    • Nonprecision:
      • Oxygen flow rate determines classification
      • No pollution
      • Can estimate anesthetic agent uptake and oxygen consumption
      • Heat and humidity conservation
      • Economy
      • Closer monitoring and more knowledge required
      • Difficult to reanesthetize a patient that wakes up
      • Danger of hypercarbia
      • Buildup of trace toxic materials, such as carbon monoxide, acetone, methane, hydrogen
    • Semiclosed:
      • Oxygen flow rate greater than 2-3 mL/lb/min
      • Some resistance
      • Some dead space
      • The rebreathing tubes are not part of the dead space

    Tranquilizers and Sedatives

    • Acetylpromazine (acepromazine) (a phenothiazine tranquilizer):
      • Actions:
        • Sedation; sometimes for long periods
        • Antidysrhythmic
        • Antiemetic; recommended to be used before opioids
        • Antihistamine effect
        • Decreases seizure threshold
        • Decreases MAC
        • Little or no analgesic effect but will make opioids more effective
      • Side effects:
        • Hypotension after large doses
        • Bradycardia, atrioventricular (AV) block
        • Sensitization to epinephrine
        • Respiratory depression in some dogs; dogs may look cyanotic because of peripheral vasoconstriction
        • May cause bloat in dogs susceptible due to gastrointestinal (GI) stasis
        • Personality changes
        • Hyperglycemia; increased urine production
        • Abortion in cattle during last trimester

    MAC

    • MAC reflects the brain partial pressure because the alveolar partial pressure is in equilibrium with the brain
    • MAC relates very closely to the concentration of the inhalant anesthetic required for maintenance anesthesia
    • 1.3 the MAC will keep 99% of the animals anesthetized
    • Combinations of inhaled anesthetics have additive effects of MAC

    Solubility

    • Solubility (partition coefficients) of anesthetics in blood and tissues determines the time necessary for equilibration between two phases to occur
    • Blood-gas solubility coefficient determines uptake from the alveoli into the blood and thus the rate of induction of anesthesia
    • Blood will hold more halothane (solubility coefficient 2.5) than isoflurane (solubility coefficient 1.4)

    Rate of Induction of Anesthesia

    • The rate of induction of anesthesia is determined by the rate of rise of the alveolar partial pressure
    • Factors that determine the rate of rise of alveolar concentration:
      • Alveolar ventilation
      • The inspired Concentration: If you use a higher concentration of anesthetic, the alveolar concentration will rise faster

    Tissue Uptake of Anesthetic

    • Factors that determine tissue uptake of anesthetic:
      • Solubility
      • Cardiac output
      • Alveolar to venous gradient

    Recovery

    • Duration is 1 to 3 hours

    Thiopental

    • Be careful in animals with cardiac disease
      • Give more slowly
      • Preoxygenate
      • Give thiopental with lidocaine
    • Reduce dose of thiopental if animal is hypoproteinemic (< 3.0 g/dL), acidotic, or extremely thin

    Sighthounds

    • Tend to overdose at beginning
    • Leads to long recovery as redistribution sites become filled
    • Hepatic metabolism is slower in sighthounds

    Critically Ill Animals

    • Shunt blood to brain and other internal organs
    • Thiopental shows greater potency in these animals

    Perivascular Injection Alkaline Solution

    • Treat with saline, lidocaine, steroids, antibiotics

    Excitement During Induction or Recovery

    • Injection too slow
    • Port on IV line distant from catheter
    • Incorrect dose

    Analgesia

    • More than one class of analgesic may be the best protocol (balanced analgesia)
      • Opioid nonsteroidal anti-inflammatory drug (NSAID)
      • Goal is to have the patient sleep and move around comfortably
    • Methods of delivery injection (including epidural, intraarticular), oral, transdermal
    • Administer pain drugs before the pain occurs (preemptive analgesia) to prevent “windup,” or the buildup of chemical mediators within the spinal cord
    • Opioids: Effective against “sore” or “achy” pain but not so effective for sharp pain
      • Morphine, hydromorphone, oxymorphone, Demerol (meperidine), fentanyl, butorphanol (mild to moderate pain, visceral pain), buprenorphine (oral in cats)
      • Intraarticular morphine: Instilled in the joint immediately before or after closure of the joint capsule
      • Epidural morphine: Contraindications include septicemia
    • -2 agonist: Medetomidine
    • Dissociative: Ketamine
    • Total intravenous anesthesia (IVA)
      • Fentanyl
      • Lidocaine
      • Morphine
      • Ketamine
      • MLK (morphine, lidocaine, ketamine)
      • Propofol

    Anesthesia Machines and Systems

    • Circle anesthesia machine: Conserves heat and moisture. Allows for gradual changes in anesthetic depth. The PaCO2 in arterial gas is determined by ventilation, not fresh gas flow.
    • Disadvantages of circle anesthesia machine: Multiple parts. Higher resistance. Difficult to clean. Not easily portable. Difficult predicting inspired concentration at low gas flows.
    • Oxygen cylinders: Green in the US and white in other parts of the world. Full cylinders contain 1900-2200 psi of oxygen.
    • Oxygen flowmeter: Indicates the flow of oxygen in liters per minute. Pressure reduction valve ensures a safe flow.
    • N2O: Compressed liquid at 750 psi when the liquid is present. Newer machines shut off N2O if oxygen is not flowing.
    • N2O - Second-gas effect: Increases the concentration of the “second gas” that is administered with nitrous oxide.
    • Circle system: The length of the endotracheal tube outside the mouth serves as the mechanical dead space. Prevents animals from rebreathing. Moisture can cause the parts to stick. Can be dislodged during cleaning.
    • Nonrebreathing coaxial system (Bain system): Oxygen flow rate of 100 mL/lb/min is recommended. This rate allows for some rebreathing. Little or no dead space. Low resistance to breathing. Sudden large flows can overpressurize and damage lungs. Disconnecting the inner limb causes respiratory acidosis.
    • CO2 absorption canister: The recommended volume is two tidal volumes. Two formulations - soda lime and baralyme.
    • Capnography: Measures the amount of CO2 exhaled. The curve shows a plateau (baseline), a spike, and an upstroke. The highest point is the end tidal CO2. If the curve does not reach the baseline, it is termed rebreathing. Low values are due to excessive ventilation, hypothermia, open thoracic surgery, tube in the esophagus, or cardiac arrest. High values are due to hypoventilation, hyperthermia, premedication effects, or anesthesia.
    • ECG: Monitors the electrical rhythm of the heart. Primarily used to detect dysrhythmias and monitor heart rate. There are many artifact causes - patient movement, lead movement, poor contact, or cauterization.
    • Reflexes: Swallowing reflex – can be assessed to assess anesthesia depth. Pupillary light reflex – can be used to assess anesthesia depth.

    Pain Control

    • Analgesia: Use multiple classes of analgesics for optimal pain control (balanced analgesia).
    • Opioids: Morphine, hydromorphone, oxymorphone, Demerol (meperidine), fentanyl, butorphanol, and buprenorphine. Not as effective for sharp pain.
    • NSAID: Use alongside opioids to provide broader pain relief.
    • Local anesthetics: Lidocaine and bupivacaine. Do not exceed 2mg/kg in dogs and 0.5-1 mg/kg in cats with bupivacaine.
    • Alpha-2 agonist: Medetomidine.
    • Dissociative: Ketamine.
    • Total intravenous anesthesia (IVA): Fentanyl, lidocaine, morphine, ketamine, MLK, propofol.

    Anesthesia Machines and Systems

    • Conservation of heat and moisture, absence of abrupt changes in anesthetic depth and a partial pressure of carbon dioxide in arterial gas (PaCO2) that depends on ventilation, not on fresh gas flow are characteristics of a circle anesthesia circuit.
    • The ideal ratio for nitrous oxide to oxygen is 2:1.
    • N2O tanks should be equipped with a device that shuts off N2O if oxygen is not flowing.
    • The Bain system (nonrebreathing coaxial system) should be used with oxygen flow rate of 100 mL/lb/min, to avoid rebreathing.
    • Do not flush the Bain system to avoid overpressurizing and damaging the lungs.

    Monitoring the Anesthetized Patient

    • Hyperventilation is a PaCO2 level in the arterial blood lower than 40 mm Hg.
    • Hypoventilation is a PaCO2 level in the arterial blood higher than 40 mm Hg.
    • Tachypnea describes a fast breathing rate.
    • The swallowing reflex should be elicited before removing the endotracheal tube (ETT).
    • The pedal reflex is not present during inhalation anesthesia.
    • The ear-flick reflex is present at all levels of anesthesia.
    • The corneal reflex is present until deep levels of anesthesia are attained.
    • The laryngeal reflex can be elicited by squirting eye-washing solution into the eye.
    • The pedal, lingual, and metacarpal arteries are all sites for superficial pulse palpations.
    • The strength of the pulse is correlated to blood pressure: a strong pulse indicates the animal is in light anesthesia.
    • The normal heart rate for horses under anesthesia is 26 to 40 beats/min.
    • The heart rate can be monitored by electrocardiogram (ECG), using an esophageal stethoscope, counting pulse rate, using a pulse oximeter, or hand palpating the chest.

    Pain Management

    • Acute pain is defined as abrupt onset with a short duration.
    • Chronic pain is slow onset and long duration.
    • Referred pain is felt in a different part of the body but is caused by injury to a different body part.
    • Hyperesthesia is an increased sensitivity to a stimulus.
    • Neuropathic pain is caused by physical damage to a nerve.
    • Allodynia is pain resulting from a stimulus that does not normally provoke pain.
    • Preemptive analgesia describes analgesia established before the onset of pain.
    • Somatic pain is sharp, stabbing, well-localized pain typically arising from skin, skeletal muscle, and the peritoneum.

    Oxygen Equipment and Use

    • Oxygen is delivered to the anesthesia machine via a pressure regulator that reduces the high pressure in the cylinder to 50 psi.
    • An “E” cylinder holds 650 to 700 liters of oxygen when full.
    • Oxygen supports combustion.
    • Oxygen cylinders should be changed when 100 to 200 psi remain.

    Vaporizers

    • Vaporizers convert liquid anesthetics to a vapor or gas state.
    • A MAC (minimum alveolar concentration) of 1.3 to 1.5 typically results in a moderate level of anesthesia.
    • Vaporizers are expensive and most are agent-specific.
    • Precision vaporizers (e.g. Tecs and Matics) are expensive and are used with anesthetics that have high vapor pressure.

    Oxygen Flow Meters

    • Oxygen flow meters measure gas flow in milliliters or liters per minute.
    • Oxygen flow should meet or exceed metabolic requirement, which is suggested to be 10 to 15 mL/lb/min (20 to 30 mL/kg/min) for a circle system.
    • If nitrous oxide (N2O) is being used, oxygen flow should be at least 30% of the total flow of oxygen and N2O.

    Rebreathing Systems

    • Circle System:
      • The circle system is a closed system that circulates respiratory gases, allowing the patient to re-breathe some of their exhaled gases.
      • The length of the endotracheal tube (ETT) outside of the mouth is considered mechanical dead space.
    • Nonrebreathing Coaxial System (Bain System):
      • The Bain system is used with small patients.
      • It has little or no mechanical dead space and offers little or no resistance to breathing.
      • Do not “flush” a Bain system; a sudden large flow may overpressurize and damage the lungs.

    CO2 Absorption Canister

    • Soda Lime:
      • Soda lime is a common CO2 absorbent, consisting of 94% calcium hydroxide, 5% sodium hydroxide, and 1% potassium hydroxide.
    • Baralyme:
      • Baralyme is another type of CO2 absorbent, consisting of 80% calcium hydroxide and 20% barium hydroxide.

    Tranquilizers and Sedatives

    • Acetylpromazine (Acepromazine):
      • Acetylpromazine is a phenothiazine tranquilizer that has sedative, antidysrhythmic, antiemetic, and antihistamine effects.
      • It also decreases seizure threshold and MAC.
      • Side effects include hypotension, bradycardia, atrioventricular (AV) block, sensitization to epinephrine, respiratory depression, and hyperglycemia.

    Monitoring the Anesthetized Patient

    • Respiratory System
      • Hyperventilation: a PaCO2 level in the arterial blood lower than 40 mm Hg
      • Hypoventilation: a PaCO2 level in the arterial blood higher than 40 mm Hg
      • Tachypnea: a fast breathing rate
    • Reflexes:
      • Pedal Reflex: present until inhalation anesthesia begins.
      • Ear-flick Reflex: present at all levels of anesthesia.
      • Corneal Reflex: present until deep levels of anesthesia.
      • Layngeal Reflex: present until deep levels of anesthesia.
    • Pulse Strength and Blood Pressure:
      • Common pulse sites include radial, femoral, dorsal pedal, lingual, metacarpal, recurrent metatarsal, and palatine arteries.
      • Pulse strength is related to pulse pressure.

    Pain

    • Acute Pain: Abrupt onset and short duration of pain.
    • Chronic Pain: Slow onset and long duration.
    • Referred Pain: Pain from a body part felt in a different part of the body.
    • Hyperesthesia: Increased sensitivity to a stimulus.
    • Neuropathic Pain: Pain from physical damage to a nerve.
    • Allodynia: Pain resulting from a stimulus that does not normally provoke pain.
    • Nociceptor: The afferent nerve ending that is sensitive to a noxious stimulus.
    • Nociception: Reception, conduction, and central nervous processing of nerve signals generated by the stimulation of nociceptors.
    • Preemptive Analgesia: Establishment of analgesia before the onset of pain.
    • Somatic Pain: Sharp, stabbing, well-localized pain typically arising from skin, skeletal muscle, and the peritoneum.

    Cardiovascular Monitoring

    • Heart Rate
      • Acceptable heart rate for cats is 100 beats/min; 80 to 90 beats/min might be acceptable before surgery starting if color, jaw tone, pulse are acceptable.
      • High range for dogs is 150 to 160 beats/min; for cats, 180 to 200 beats/min.
      • Normal heart rate for horses during anesthesia is 26 to 40 beats/min.

    Second Gas Effect

    • Rapid uptake of N2O increases effective minute ventilation and the rate of uptake of concomitantly inhaled gases (isoflurane, oxygen).
    • The uptake of N2O also contracts the alveoli concentrating the remaining gases.

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    Description

    This quiz covers essential concepts related to vaporizers and anesthesia systems, including the factors affecting vaporizer output and classifications of anesthesia systems. It also discusses tranquilizers and sedatives in the context of anesthetic practices. Enhance your understanding of these critical components in anesthesia.

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