Anesthetic Principles Test 1

A comprehensive vocabulary review of 120 key principles, drug classifications, monitoring parameters, and clinical protocols for veterinary anesthesia.

Anesthesia

The loss of sensation in a patient.

General Anesthesia

A reversible state of CNS depression produced by anesthetic agents, characterized by loss of consciousness, amnesia, loss of pain, and immobility.

Local Anesthesia

Anesthetic technique that targets small, localized areas of tissue.

Regional Anesthesia

Anesthetic technique that affects larger nerve areas, often administered as nerve blocks.

Topical Anesthesia

Anesthesia that is strictly limited in effect to the skin and subcutaneous tissues.

Neuroleptanalgesia

A profound state of sedation and analgesia induced by administering an opioid and a tranquilizer concurrently.

Anxiolytics

Any pharmacological agents that reduce anxiety, a broad drug category that includes sedatives and tranquilizers.

Sedatives

Drugs that reduce awareness, induce CNS depression and drowsiness, and leave the patient minimally aware.

Tranquilizers

Drugs that induce a state of calm without drowsiness, leaving the patient aware but unconcerned, unwilling to move, and rousable.

Anesthesia Continuum of Care

The concept that anesthesia is a continuous, multi-phase process managing patient safety, comfort, and physiological stability from start to finish, beginning and ending at home.

Visual Anesthetic Safety Aids

Tools such as checklists, algorithms, and tip boxes that enhance guideline usability and allow rapid information access.

Individualized Anesthetic Plan

A customized anesthetic protocol tailored to high-risk patients ($\text{ASA Class III}$ and above) and non-routine surgical procedures.

Standardized Anesthetic Plan

A routine anesthetic protocol best suited for lower ASA category patients undergoing standard procedures, promoting staff familiarity with expected outcomes.

Balanced Anesthesia

Combining multiple drugs for safety and efficacy, reducing adverse risks through constant vital monitoring and patient-tailored dose adjustments.

Preanesthesia Phase

The initial phase of anesthesia dedicated to patient planning, assessment, and equipment setup.

Induction Phase

The second phase of anesthesia that transitions the patient from a conscious state into unconsciousness.

Maintenance and Recovery Phases

The third phase sustaining a surgical plane of unconsciousness, followed by the fourth phase where administration ends and the patient regains consciousness.

Preanesthetic Patient Evaluation

Comprehensive clinical assessment incorporating patient history, physical examination, diagnostic tests, and factors like age, breed, size, and temperament.

Admission Anesthetic History

Pre-procedure inquiry verifying concurrent illnesses, concurrent medications, prior anesthetic history, fasting status, and confirmation of the scheduled procedure.

Recommended Pre-anesthetic Diagnostics

Baseline screening tests including PCV and TP, CBC, blood chemistries, urinalysis, radiographs/imaging, and ECG.

Anesthetic Release Forms

Clinic documentation encompassing informed consent, emergency contact numbers, a written cost estimate, and CPR resuscitation status ($\text{ALS}$ or $\text{BLS}$).

ASA Class I and Class II

Patient physical status classifications representing minimum anesthetic risk (Class I / C1) and slight anesthetic risk (Class II / C2).

ASA Class III (C3)

The patient physical status risk classification defined as moderate anesthetic risk.

ASA Class IV and Class V

Patient physical status risk classifications representing high anesthetic risk (Class IV / C4) and grave anesthetic risk (Class V / C5).

Pre-anesthetic Food Fasting

The standard protocol of withholding food for $4\text{--}6\text{ hours}$ and up to $12\text{ hours}$ prior to general anesthesia.

Pre-anesthetic Water Access

The recommendation to allow water access until premedication is administered to avoid patient dehydration.

Fasting Protocol Exceptions

Patient groups exempt from standard fasting: neonates, birds, rabbits, laboratory animals, adult patients weighing $< 2\,\text{kg}$, and diabetics.

Pre-anesthetic Drug Benefits

Calming or sedating the patient, producing synergistic dose reductions of induction and maintenance agents, and counteracting negative drug side effects.

Opioid Premedications

Analgesics that bind to CNS opioid receptors to block pain signals; used with caution in patients with head trauma, respiratory depression, or bradycardia.

Alpha-2 Agonists

Agents stimulating alpha-2 receptors to decrease norepinephrine release, producing sedation, analgesia, and muscle relaxation; reversible with antisedan.

Benzodiazepines

Drugs enhancing GABA activity to cause anxiolysis, muscle relaxation, and anticonvulsant effects; avoided in liver disease and may cause excitement in young animals.

Phenothiazines

Dopamine receptor antagonists providing tranquilization and antiemetic effects; contraindicated in hypotension, seizures, liver dysfunction, or geriatrics.

Third Eyelid Prolapse

A characteristic clinical sign commonly observed following the administration of phenothiazine tranquilizers such as acepromazine.

Dissociatives

NMDA receptor antagonists producing dissociative anesthesia and analgesia; contraindicated in patients with head trauma, seizures, or cardiac disease.

Neurosteroids

GABA-modulating agents used for IM sedation and IV induction; convenient for IM use in fractious cats, though carry respiratory depression risks in large volumes.

Pre-Visit Pharmaceuticals (PVP)

Anxiolytics like gabapentin or trazodone that modulate GABA and serotonin to reduce fear, anxiety, and stress (FAS) before clinic visits.

Fentanyl

A profound full mu/kappa opioid agonist lasting $20\text{--}30\text{ minutes}$; administered via bolus, CRI, or patch, with risks of bradycardia and respiratory depression.

Morphine

A profound opioid analgesic lasting $2\text{--}4\text{ hours}$; causes vomiting when given IM and histamine release when given IV; often co-administered with a tranquilizer.

Hydromorphone

A profound opioid analgesic lasting $2\text{--}4\text{ hours}$; similar to morphine without histamine release, but carries a risk of hyperthermia in cats.

Methadone

A profound opioid analgesic lasting $2\text{--}4\text{ hours}$; functions as an NMDA antagonist, causes less vomiting than morphine, and produces sedation.

Buprenorphine

A partial mu agonist providing moderate analgesia lasting $4\text{--}8\text{ hours}$; has a slow onset, minimal sedation, and is well-suited for cats.

Butorphanol

A kappa agonist / mu antagonist providing mild to moderate analgesia lasting $20\text{--}90\text{ minutes}$; acts as an effective sedative when paired with a tranquilizer.

Antisedan (Atipamezole)

The specific reversal agent used to antagonize the sedative and physiological effects of alpha-2 agonists.

Anticholinergic Premedication Decline

The decrease in pre-anesthetic anticholinergic use because they wear off prior to induction, do not improve outcomes, and do not reduce maintenance gas requirements as well as analgesics.

Anticholinergic Physiological Effects

Parasympatholytic actions causing decreased heart rate and respiratory rate, pupil constriction, increased respiratory secretions, and increased gastrointestinal peristalsis.

Anticholinergic and Alpha-2 Agonist Contraindication

Concurrent administration causes competing sympathetic stimulation that raises blood pressure to $150\text{--}160\,\text{mmHg}$ and excessively elevates myocardial oxygen demand.

Role of Induction Agents

Injectable or inhalant drugs used to take a patient from a conscious state to unconsciousness, amnesia, and analgesia.

Preoxygenation

Delivering $100\%$ oxygen for $3\text{ minutes}$ prior to induction, which saturates hemoglobin for approximately $6\text{ minutes}$.

Dosing to Effect

Drawing the calculated dose but injecting one-quarter to one-half aliquots at short intervals until jaw relaxation and laryngeal reflex loss permit intubation.

Post-Bolus Apnea

Transient respiratory depression following rapid IV bolus administration of induction agents, most commonly seen with thiopental, propofol, and alfaxalone.

Propofol

A phenol induction agent with rapid onset and short duration, easily titrated to effect, but lacking analgesia and causing dose-dependent cardiorespiratory depression.

Propofol Emulsion Vehicle

An unpreserved lipid formulation that supports rapid bacterial proliferation once an ampoule or vial is opened.

Alfaxalone

A neurosteroid induction agent suitable for IV induction or IM sedation in fractious cats; cons include hypotension, apnea, and muscle twitching during recovery.

Ketamine

A cyclohexamine dissociative agent providing analgesia and aggressive animal restraint, but causing muscle rigidity, tachyarrhythmias, and potential rough recoveries.

Catalepsy

A dissociative anesthetic state where the patient appears awake with open eyes and central pupils, accompanied by muscle rigidity.

DKT (Kitty Magic)

An off-label feline anesthetic mixture combining dexmedetomidine, ketamine, and butorphanol in equal $1:1:1$ volumes within a single syringe.

DKT Formulation Strengths

The standard constituent strengths used in Kitty Magic: dexmedetomidine ($0.5\,\text{mg/mL}$), ketamine ($100\,\text{mg/mL}$), and butorphanol ($10\,\text{mg/mL}$).

Thiopental

An ultra-short-acting barbiturate used for rapid induction and seizure control, discontinued in Canada and the US due to severe tissue necrosis and cardiorespiratory depression.

Phenobarbital

A barbiturate class medication categorized as short-acting and most commonly used.

Dissociative-Benzodiazepine Co-administration

The practice of combining ketamine with a benzodiazepine to alleviate adverse muscle rigidity and catalepsy.

Diazepam Administration Constraints

A benzodiazepine that must be administered strictly IV and can only be safely combined in the same syringe with ketamine.

Mask or Chamber Induction

An inhalant induction method indicated for fractious patients, associated with stress, excitement phases, delayed airway access, and staff waste gas exposure.

Inhalant Maintenance Advantages

Rapid depth titration, minimal drug metabolism allowing longer and safer anesthesia, and controlled oxygen supplementation via an endotracheal tube.

Inhalant Maintenance Disadvantages

Requirement for specialized equipment, higher financial costs, waste gas production, and environmental contamination.

Ideal Anesthetic Gas

A theoretical agent that is non-toxic, non-flammable, inexpensive, causes minimal organ depression, allows rapid depth changes, and provides muscle relaxation and analgesia.

Vaporizer Delivery System

Equipment where liquid anesthetic evaporates and blends with carrier oxygen to form fresh gas delivered to the patient breathing circuit.

Inhalant Gas Concentration Gradient

The pharmacokinetic pathway where anesthetic vapor diffuses from alveoli into blood and traverses into the brain along concentration differences.

Vapour Pressure

The physical tendency of a liquid anesthetic to evaporate at room temperature, with higher pressure reflecting greater volatility.

Ideal Vapour Pressure

A low vapour pressure rating, ensuring the liquid agent is less volatile, easier to control, and less prone to accidental excessive delivery.

Solubility Coefficient

A measure of how easily an anesthetic gas dissolves in blood compared to alveolar gas; in theory, the most important determinant of induction and recovery speed.

Ideal Solubility Coefficient

A low solubility coefficient, allowing the anesthetic to remain in alveolar gas and rapidly establish brain tension for fast induction and recovery.

Minimum Alveolar Concentration (M.A.C.)

The measure of anesthetic potency, defining the lowest alveolar concentration preventing gross purposeful movement in response to noxious stimulation.

Ideal M.A.C. Value

A low MAC value, indicating greater anesthetic potency so that a lower concentration is required to maintain surgical anesthesia.

Isoflurane

The most commonly used inhalant in small animal clinics; features low MAC and minimal liver metabolism, but possesses a pungent odor and lacks post-op analgesia.

Sevoflurane

An inhalant used in exotics, avian, and referral medicine with rapid depth changes, but $7\text{--}8\times$ more expensive and possessing a higher MAC than isoflurane.

Halothane

A historical inhalant withdrawn in Canada that causes cardiac dysrhythmias, hypotension, and $20\%$ liver metabolism associated with staff exposure risks.

Thimol Preservative

A chemical stabilizing additive in halothane that accumulates in precision vaporizers over time, necessitating frequent servicing.

Methoxyflurane

A historical inhalant characterized by very slow induction and recovery due to high blood solubility, severe respiratory depression, and risks of renal and hepatic toxicity.

Diethyl Ether

A volatile historical agent that caused operating room fires and explosions, post-operative nausea, and long-term risks of liver disease and cancer.

Diffusion Hypoxia

A complication where nitrous oxide rapidly diffuses out of blood into alveoli upon discontinuation, diluting alveolar oxygen and causing hypoxemia.

Diffusion Hypoxia Prevention

Administering $100\%$ oxygen for at least $5\text{ minutes}$ immediately after terminating nitrous oxide delivery.

Stage I Anesthesia

The initial stage of disorientation just prior to loss of consciousness, featuring normal vitals, intact reflexes, and reduced pain sensitivity.

Stage II Anesthesia (Excitatory Stage)

The excitement and dysphoria stage characterized by fluctuating vitals and exaggerated reflexes, which is ideally bypassed during induction.

Stage III Anesthesia (True Anesthesia)

The sleep and surgical stage consisting of four planes, characterized by unconsciousness, decreased heart rate and respiratory rate, and muscle relaxation.

Stage IV Anesthesia (Terminal Stage)

The terminal stage marked by respiratory arrest and circulatory collapse, requiring immediate life support interventions.

Purpose of Patient Monitoring

Identifying, preventing, and responding to extreme physiological instability in a timely manner to reduce anesthetic mortality.

Hands-on Continual Monitoring

Continual physical assessment performed by a dedicated anesthetist alongside electronic devices, requiring full and constant attention.

Intraoperative Recording Frequency

The mandatory recording of patient vital signs and anesthetic parameters at least once every $5\text{ minutes}$.

Post-Extubation Monitoring Schedule

The protocol of recording patient vital statistics every $15\text{ minutes}$ after extubation until normal values and sternal recumbency are reached.

Vital Signs (TPR)

Ongoing physiological measurements of body function that are altered by anesthetic depth but are never completely extinguished.

Cardiovascular Monitoring Methods

Assessing circulatory function using pulse palpation, stethoscope auscultation, ECG, pulse oximetry, and Doppler or oscillometric blood pressure units.

Respiratory Monitoring Methods

Assessing ventilation via visual observation of chest and rebreathing bag excursions, tactile air flow sensation, and capnography.

Temperature Monitoring Modalities

Tracking body temperature using digital rectal or axillary thermometers, or continuous esophageal temperature probes.

Eye Position Depth Indicators

The rotation of the globe ventromedially during moderate surgical planes of anesthesia, returning to central position during light or dangerously deep planes.

Muscle Tone in Anesthesia

The amount of resistance encountered when manipulating or flexing jaw, limbs, or anal sphincter to gauge anesthetic depth.

Jaw Tone Assessment

Evaluating mouth opening resistance; a tight jaw indicates light anesthesia, while a flaccid jaw indicates excessive depth.

Peripheral Muscle Tone Assessment

Checking the tightness of the anal sphincter, tail resistance, or limb flexion resistance to corroborate anesthetic depth.

Palpebral Reflex

The protective blinking response elicited by gently touching the medial or lateral canthus of the eyelid.

Pedal Reflex

The withdrawal response of a limb in small animals triggered by pinching an interdigital toe web.

Swallowing (Laryngeal) Reflex

A pharyngeal throat reflex whose return signals recovering consciousness and readiness for extubation in dogs.