Summary: This chapter is devoted to developing the physical/chemical properties of the volatile (inhalation) anesthetics so that the specific advantages and disadvantages associated with each agent so that appropriate decisions can be made by the anesthetist. The pharmacokinetics (uptake, distribution, metabolism and elimination) as well as the pharmacodynamics, particularly as it applies to the cardio-respiratory systems and quality of anesthesia are further developed to assist the practitioner in making the best choice(s) of agent(s) based on the a animal’s health, procedure, mitigating circumstances etc.
Questions: 1. The authors cite eleven (11) characteristics of the “ideal” volatile anesthetic. One such quality is “low solubility in the blood”. This characteristic will directly determine ___________________ of the agent.
a. the cost of the procedure in terms of consumed anesthetic material
b. the rapidity with which the animal can be induced and recovered
c. the potential for adversely affecting respiratory control centers
d. the need to premedicate the animal patient with anticholinergic drugs.
2. The rate of equilibration of the inhaled anesthetic with brain tissue is a function of ________________________________
a. the percent (%) setting on the vaporizer selector
b. the rate and volume of breathing (minute ventilation)
c. the blood and fat solubility of the agent
d. the brain blood flow and blood solubility of the agent
3. The vapor pressure of a volatile anesthetic ______________________________.
a. is inversely related to the rate at which the animal can be anesthetized
b. may require than an inert gas like nitrogen be used as part of the carrier mixture
c. is directly related to the maximum concentration that can be achieved in the inhaled volume
d. determines the speed at which the brain tissue can be equilibrated at an anesthetic level
4. The more soluble a volatile anesthetic is in blood compared to air, ________________________.
a. brain tissue will reach equilibrium with the anesthetic in the blood compartment more quickly
b. one can anticipate that a large percentage of the volatile agent will be metabolized in the liver
c. the lower is the required alveolar concentration of anesthetic for brain tissue equilibrium
d. correspondingly greater time will be required to bring brain tissue into equilibrium and anesthesia.
5. T/F. The smaller the animal, the more rapid brain tissue is brought into equilibrium with the inhaled alveolar concentration.
6. Of the following, __________________________________ would be most likely responsible for decreased rate of anesthetic induction.
a. uptake of anesthetic gas by the material of the anesthetic circuit.
b. fresh soda lime in the chamber of the vaporizer
c. a vaporizer indicating ½ full on the glass cage of the loading tank
d. using a volatile anesthetic with a high vapor pressure
7. T/F. The larger the animal, the more quickly will the brain can come into equilibrium with the partial pressure of a volatile anesthetic in the blood compartment, and the more rapid will be induction.
8. The Minimum Alveolar Concentration (MAC) [equivalent to the ED50 for pharmacological dose response curves], is _________________________________
a. the volume of alveolar gas exchanged with each breath multiplied by the rate of breathing
b. the concentration of volatile anesthetic in the blood that will produce anesthesia
c. the concentration of volatile anesthetic in the brain that will produce anesthesia in 50% of the test subjects.
d. the concentration of volatile agent in the alveolar air required to produce analgesia in 50% of the test subject.
9. The Isoflurane MAC for dogs, people and monkeys is the same, i.e., ~1.28 0.05%. This means
a. isoflurane has the same potency in these three species
c. the higher metabolic rate of dogs will make isoflurane more potent in this species
d. people would have to positioned as quadrupeds in order to have isoflurane potency equivalent to dogs.
10. Several factors, including age, core temperature, circadian rhythm and concomitant use with other depressant agents influence MAC values. For methoxyflurane and halothane, this effect has been determined to be 5% for each degree centigrade loss of body heat. This being so, the lowering of the core temperature in a dog anesthetized with halothane (MAC = 0.87%) from 37.5 to 36.0 would reduce the MAC to ___________
a. 0.93% b. 0.0825% c. 0.08% d. 0.072%
11. Factors that do influence (increase or decrease) MAC for any agent include _____________________
a. age, catecholamine releasers, other volatile anesthetics, and sedatives
b. catecholamine releasers, sedatives, sex, weight and strain
c. other volatile anesthetics, sex, strain, and blood pressure
d. arterial oxygen saturation . 40 mm Hg, sedatives, strain, and blood pressure
12. Metabolism of some halogenated volatile anesthetics leads to toxic end products that target the ___________________________ and ________________.
a. lung , liver and bone marrow
b. liver and kidney
c. exocrine pancreas and kidney
d. bone marrow and kidney
13. A precise molecular mechanism for anesthesia with volatile agents is not know. Much attention is currently focused on the movement of ions in membrane channels as influenced by the __________________ neurotransmitter(s) and associated receptors as a molecular mechanism of anesthesia with these agents.
a. alpha2 adrenergic
b. beta adrenergic
d. gamma aminobutyric acid
14. For the canine, the MAC for nitrous oxide is calculated to be 188 35%. Based on this information, _____________________________________.
a. surgical anesthesia can be safely produced in dogs with 94% nitrous oxide and 6% oxygen
b. surgical anesthesia can not be produced without concomitant hypoxemia
c. at least 70% of neutered dogs would not feel a pinch at this inhaled concentration
d. the nitrous oxide would have to be administered under hypobaric conditions to produce anesthesia
15. T/F. Nitrous oxide is very soluble in blood and tissue fluids, requiring a very long time for equilibrium to be reached, surgical anesthesia to be produced and the animal to return to consciousness.
16. Methoxyflurane (metofane) is the most potent of currently used volatile anesthetics but is rarely used in the human arena and its recent removal from the U.S. market drastically reduced its use for laboratory animals species. The central reason for the drastically reduced use in both arenas is due to ________________________-.
b. the need for very expensive, calibrated high flow, temperature insensitive vaporizers
c. the toxicity of the metabolic products, even at low concentrations over long periods of time
d. the inability of F-air activated charcoal filters to absorb this agent
17. Halothane has a low solubility in blood and tissue, a high vapor pressure of about 1/3 of an atmosphere (33%) and the MAC for halothane 0.87%. This combination of features ____________________________.
a. provides for slow equilibrium of brain with the alveolar concentration and increased time for surgical anesthesia
b. assures the anesthetist that the patient can not received more than one or two times the MAC value during the surgery
c. initiates a very rapid induction to surgical anesthesia but a prolonged recovery
d. provides for a both a rapid induction and a rapid recovery.
Isoflurane is roughly twice as safe as halothane under the same conditions and in the same species because _________________________________.
isoflurane has less depressant activity on the myocardium
isoflurane exhibits increased tendency to sensitize the myocardium to exogenous catecholamines
isoflurane is not a hepatic microsomal p450 induction agent while halothane is
isoflurane is so rapidly metabolized it does not build up toxic levels of the agent in the liver.
For an accurate assessment of the alveolar concentration of a volatile anesthetic, ____________.
the gas mixture on the intake side of the endotracheal tube should be sampled
the gas mixture after being scrubbed by the soda lime chamber should be sampled
the gas mixture that is expelled at the beginning of expiration should be sampled
the gas mixture that is expelled at the end of the expiration should be sampled
Infrared excitation spectroscopy can be used to measure the concentration of a volatile anesthetic in the expired air since each of the agents has a unique spectral profile, little influence by water vapor, etc. This allows ________________
for sampling of several agents being used simultaneously
only the maximum concentration of any one agent to be determined
only the minimum concentration of any one agent to be determined
the anesthetist to adjust the venitlator to change the depth of anesthesia
Anesthesia and Analgesia in Laboratory Animals
Chapter 3 Summary: Chapter looks at the site(s) of interaction of the major chemical classes of analgesics and how they ameliorate pain, triggered by a number of stimuli in the peripheral and central nervous system.
1. Non-steroidal anti-inflammatory drugs (NSAIDS) detailed mechanism is not always known. However, a common effect of all these agents is inhibition of _______________.
a. arachidonic acid synthetase
b. phospholipase A
2. T/F. Prostaglandins increase the sensitivity of noccioceptors to other chemicals and/or medicines and/or thermal stimuli.
3. T/F. Cyclooxygenase may be inhibited in an irreversible manner by some NSAIDS.
4. The inhibition of the prostaglandin,____________, is fundamental to the antipyretic effects of the NSAIDs that possess this activity.
5. The side effects associated with aspirin use are considered to be subsequent to inhibition of the enzyme __________________.
a. phospholipase 2
c. prostaglandin synthetase
d. alanine aminoasparatase
e. concanavillin C
6. Inhibition of _________________production due to the pharmacologic effect of prostaglandins results in gastric ulceration when this function is blocked by NSAIDS.
a. hydrochloric acid
e. phospholipase A
7. The platelet aggregating agent released when prostaglandins are synthesized normally from arachidonic acid metabolism is __________________.
8. The target organ for the non-enteric aspirin toxicity in most animals is the __________________________.
e. urinary bladder
9. When given 44 mg/kg of aspirin, intravenously, the following elimination half- lives (hrs) were noted for the species: cat (37.6), dogs (9.6), pig (5.9), pony (1.03) and goat (0.78). This very large difference between the cat and the other species is due to ___________________________________________in the cat and _________________in the other species.
a. decreased metabolism: decreased glomerular filtration rate
b. increased metabolism: alkaline urine
c. increased metabolism: acid urine
d. decreased hepatic metabolism; relatively alkaline urine
e. increased enterohepatic recirculation: acid urine
10. All of the NSAIDS are highly bound to _________________________ and displacement by endogenous chemicals or agents administered to the patient may affect the ___________________________ of the supplied NSAID
a. myoglobin: absorption
b. serum albumin: distribution, metabolism and elimination
c. serum gamma globulin: absorption and elimination
d. hemoglobin: distribution and elimination
e. sarcoplasmic reticulum: metabolism and elimination
11. An alpha adrenergic receptor agonist NOT associated with analgesia in animals is _____________________.
a. detomidine b. clonidine c. phenylepherine
d. xylazine e. medetomidine
12. The action of alpha-adrenergic agonist agents for sedation and analgesia is localized to neurons in _________________________
a. the nucleus of the trigeminal nerve
b. the locus coeruleus
c. the optic chiasma
d. the amygdale
e. the livery nucleus
13. The tissue receptor most involved in the analgesic mechanism of action of opioids is the _________________receptor.
14. Central analgesia and respiratory depression of opioid analgesics is associated with the ____________________receptor.
15. T/F. Opioids are most effective for pain of the sharp, intermittent type that is associated with the viscera.
16. T/F. Opioids are not very effective at the control of neuropathic pain (pain associated with nerve damage)
17. A group of animals that appears to be unaffected by morphine, in terms of analgesia, are the ____________________.
18. Currently, there are several NSIADS on the market that tout a more specific cyclooxygenase 2 inhibitors. These agents belong to the __________________
b. Propionic acid derivative
19. Kappa receptors, promoting analgesia when activated by the appropriate agonists, are located primarily in _____________________-
a. the cerebral cortex
b. the spinal cord
c. the hypothalamus
d. the pituitary gland
e. the limbic system
20. Fentanyl is considered to be _________________times more potent than morphine.
a. ~40 times
b. ~80 times
c. ~ 300 times
d. ~ 10 times
e. ~ 25 times
21 If one wanted to acutely reverse an opioid induced respiratory depression in a patient, one agent that might be given would be ___________________.
Chapter 4 - Paralytic Agents. 1. T/F. Hypothermia exacerbates and prolongs neuromuscular blockade.
2. T/F. Current neuromuscular blocking agents with a mechanism of action peripheral to the brain are classified as (a) depolarizing and (b) non-depolarizing agents.
3. T/F. Guaifenesin in a 5 or 10% solution in saline or 5% dextrose can be used intravenously to make horses and cattle loose control of tonic (supporting) muscle groups and become recumbent
4. T/F. Succinylcholine, an example of a depolarizing neuromuscular blocking agent, is a competitive antagonist at the postjunctional (motor endplate) acetylcholine receptor site.
5. T/F. The muscle of the face are more resistant to the effects of neuromuscular blocking agents than are those of the limbs.
6. T/F. The ED50 (dose required to cause a 50percent reduction in evoked twitch) is the level of blockade used for comparison of one agent with another.
7. T/F. Curare and the other agents in this class (benzylisoquiniloniums) cause histamine to be released when they are used as neuromuscular blocking agents.
8. Succinylcholine by itself but more often combined with the use of halothane puts an animal patient at risk for development of _____________________ during the anesthetic protocol.
a. paroxysmal tachycardia
b. orthostatic hypotension
c. runs of ventricular ectopic beats
d. malignant hyperthermia
8. Nondepolarizing neuromuscular blocking agents are __________________________ and ______________________ in their action at the postjunctional membrane receptor.
a. non-competitive with acetylcholine: nondepolarizing
b. competitive with acetylcholine: nondepolarizing
c. competitive with acetylcholine: depolarizing
d. non-competitive with acetylcholine: depolarizing
9. Curare and some of its new analogs have prominent sympathetic ganglion blocking activity (nicotinic effect) which might produce __________________ in an animal patient.
10. The neuromuscular blocking action of curare and curare-like agents can be prolonged and intensified by the use of the ________________________antibiotics.
11. Of the following, _______________ have not been recognized as good models for various aspects of the pharmacologic and pharmacokinetic effects of nondepolarizing neuromuscular blocking agents.
a. pigs and cats
b. sheep and dogs
c. ferrets and ponies
d. calves and badgers
12. When monitoring an animal patient that has been paralyzed with a neuromuscular blocking agent, ______________________ would not be an appropriate way to assess depth of anesthesia.
a. acceleration or slowing of the heart beat
b. jaw tone
c. arterial blood gas sampling
d. arterial blood pressure.
13. The chemical released from the motor nerve, onto the motor endplate, resulting in depolarization and contraction of the muscle under normal conditions, is __________________________.
a. norepinephrine b. serotonin c. gallamine d. GABA e. acetylcholine
Chapter 5: Monitoring Anesthesia Summary: This chapter briefly underscores the importance of anesthesia monitoring from the view point of the safety of the animal patient and the impact that uncontrolled events during anesthesia might have on utility of that information for a data point. The emphasis is always that the anesthetists powers of observation are of primary importance with the support of technology. Different technologies are reviewed for monitoring the effect of anesthesia on the cardio-respiratory and central nervous systems.
1. The acute welfare of the patient under general surgical anesthesia is dependent upon the integrity of the _____________________________ systems.
a. central nervous ; renal; and musculo-skeletal
b. central nervous ; cardiovascular; and respiratory
c. musculo-skeletal; respiratory; and cardiovascular
d. cardiovascular; respiratory and musculo-skeletal
2. T/F. Electronic monitoring of anesthetized patients should be used to reinforce the clinical observations of the anesthetist.
3. A component of monitoring the cardiovascular system that is not observational would be _______________________.
4. Bradycardia, signifying a(n) _______________heart rate is/ is not species dependent and does/does not suggest a potential problem when it occurs during surgical anesthesia.
a. accelerating; is; does not
b. decelerating; is ; does
c. decelerating; is; does not
d. accelerating; is not; does
5. All of the following might be associated with a tachycardia during a surgical procedure except _____________________.
a. administering a alpha-adrenergic blocking agent
e. administering atropine
6. T/F. The absence of a palpable pulse during anesthesia, but present before induction, is always considered a significant sign of a potential problem.
7. A prolonged capillary refill time might be caused by all of the following except ________________________.
a. administration of xylazine
b. decreased cardiac output
e. administration of ketamine
8. T/F. A normal configuration in an electrocardiogram “strip” confirms that the cardiac output is normal.
9. By convention, a mean arterial pressure of ________________or less, is considered inadequate for tissue perfusion.
a. 80 b. 75 c. 70 d. 60
10. During anesthesia, a systolic pressure of 119 mm Hg (torr) and a diastolic pressure of 44 mm Hg (torr), would result in a mean arterial pressure of ________________mm Hg (torr).
a. 64 b. 69 c. 76 d. 60
11. Conventional Swan-Ganz catheters, introduced into the pulmonary artery, can measure all of the following except __________________.
a. pulmonary artery “wedge” pressure
b. cardiac output
c. central venous pressure
d. systolic pressure
e. diastolic pressure
12. A “rule of thumb” for setting ventilator volumes when mechanically ventilating an anesthetized patient is 10-15 ml/kg. This value is considered as the ______________ for this animal.
13. T/F. There is usually an inverse relationship between the rate of breathing and metabolic rate of an animal.
14. Of the following, ____________________ partial pressure is the blood is considered the major stimulation on the medulla respiratory control centers for increasing the rate of breathing.
a. increased carbon dioxide
b. increase nitrogen
c. decreased oxygen
d. decreased carbon dioxide
e. increased carbon monoxide
15. Assessing partial pressure of carbon dioxide in the expired air of anesthetized patients is referred to as _________________________.
16. Oximeters are used to measure ______________________.
a. the iron content of hemoglobin in the patient’s blood
b. the saturation of blood hemoglobin with oxygen
c. the saturation of muscle myoglobin with oxygen
d. the partial pressure of nitrogen in the blood
e. the rate of hemoglobin saturation or desaturation with oxygen
17. The units of the numbers appearing in the oximeter readout are _________________.
a. mm Hg b mg/L. c. torr d. beats per minute e percent
18. Thermoregulation, often upset by sedative drugs and general anesthesia, has its control center in _______________ of the brain.
a. the hypothalamus
b. the neurohypophysis
c. the thalamus
d. the amygdale
e. the pituitary
19. All of the following, excepting _________________, would be recommended methods to allay and/or reverse hypothermia in an anesthetized patient.
a. placing the animal on an electric heating pad
b. injection of warm electrolyte solutions under the skin
c. giving warm saline enemas
d. wrapping the limbs with insulating materials
e. minimizing the time the abdominal cavity is opened.
30. Describe the formalin and carrageenan models of chronic pain
31. Name clinical signs commonly seen with nerve injury models
BB Anesthesia Chapter 7: Anesthesia Equipment: Types and Use 1). By definition of their use, intubation guides become tube exchangers when they are used to replace an existing endotracheal tube. True or False.
2). The tube exchangers are used to switch an exciting endotracheal tube during this process there is no delivery of breathing gases. True or False
3). Which of the following statements are false.
a). Endotracheal tubes made of rubber are opaque, polyvinyl tubes are the lightest and those of made of silicone can be repaired by the manufacturer.
b). The tube size is determined by the internal diameter and as this increases so does the length of the tube.
c). Endotracheal tubes can be modified or manufactured to have an opening near its distal end called a Murphy's eye which serves as an alternative respiratory pathway in the event the tip should be blocked by secretions.
d). High pressure, high volume cuffs require large volumes of gas forming a greater area of tracheal seal which reduces the chance of necrosis.
4). The H tanks are designed to fit the smaller anesthetic units by connecting directly to the anesthetic machine by a yoke. True or False
5). Match the following:
Oxygen a). Yellow tank, one of the three ost Common compressed gases
Nitrogen b). Black tank, gas of choice on Pneumatic drills
Carbon Dioxide c). Green tank commonly mixed with nitrous To achieve effect
Nitrous Oxide d). Gray tank, used to insufflate for laproscopic procedures
Compressed Air e). Blue tank, used as a supplemental gas For anesthesia
6) All small cylinder yokes should conform to the PIN Index Safety System to assure minimal safety standards. True or False.
7). What is DISS?
8). Dual flowmeters allow for the more precise control of different types of gases. True or false?
9). Name two gases that are used that are partially in a liquid phase in the tanks?
10). The oxygen flush valve can be regulated by the flowmeter so it is best set low to minimize the chance of barotrauma in rodents?
11). The common gas outlet if conforms to the ASTM standard is a female 15mm fitting which is the same size as the endotracheal tube this prevents accidental connections to the wrong port. True or False?
12). The APL valve diameter is a male fitting which is identical to the breathing circuit valves this allow for the same tubing to be used. True or false ?
13). A reservoir bag should be 3- 5 times the volume of the gas entering or leaving the patient which is commonly referred to as tidal volume True or False?
14). Precision vaporizers can be used with the following agents except _____ which requires a heated pressurized vaporizer designed for that agent?
15). Define linearity as it pertains to variable bypass vaporizers and name two physical factors that impact it.
16). Due to their flexability, ease of use and safety makes the nonprecision vaporizers the preferred choice for laboratory animal medicine. T or F
17). In an active scavenging system the positive pressure relief valve serves to protect the breathing circuit from high pressures while the negative pressure relief valve serves to prevent excess vacuum from being applied to the breathing circuit. T or F
18). Define physiologic dead space.
19). Hypoventilation can occur in small patients that are mechanically ventilated under adequate volume settings due to circuit compliance. T or F.
20). Which commonly used Mapleson non-rebreathing circuit has fresh air delivered near the endotracheal tube or mask connection. As a result changes in vapor pressure are rapidly detected in the circuit and the patient?
21). The Harvard pump is a generic name for what type of ventilator and state the type of injury that can occur using standard volume settings?
22). If induction chambers are used, a good rule of thumb is to match the size of the animal to the size of the chamber to facilitate the induction. T or F
23). When using pure oxygen as the carrier gas there is no advantage in using an in the circuit oxygen-sensing port when operating a closed circuit or low flow technique to determine low oxygen level. T or F
24). Both oxygen and carbon dioxide levels can be detected using by infrared analysis, Raman spectroscopy and mass spectroscopy T or F