ACVAA flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

MAC definition

Minimum alveolar concentration at one atmosphere preventing movement in 50% of subjects given a supramaximal stimulus; a comparative potency index, not a procedure-specific ED50.

Isoflurane MAC dog

Approximately 1.3-1.6% in dogs; clinically useful as the reference point for judging vaporizer settings and depth in canine inhalant anesthesia.

Sevoflurane MAC dog

Roughly 2.1-2.6% in dogs, about half the isoflurane value; lower blood solubility also speeds induction and recovery compared with isoflurane.

MAC-sparing effect

Reduction in inhalant requirement when injectable anesthetics, opioids, or alpha-2 agonists are co-administered; typical reductions are 20-50% depending on drug and dose.

Hypothermia and MAC

Body temperature is directly related to MAC; hypothermia lowers anesthetic requirement, so a patient cooled during surgery may be relatively overdosed at a fixed vaporizer setting.

Preoxygenation purpose

Breathing 100% oxygen for 3-5 minutes before induction increases functional residual capacity oxygen stores and prolongs safe apnea time in critical or brachycephalic patients.

Capnography phase III

The alveolar plateau of the capnogram; its presence confirms gas from alveoli and its slope reflects ventilation-perfusion mismatch rather than airway integrity alone.

Esophageal intubation sign

Absent or rapidly declining end-tidal CO2 with a waveform lacking a normal alveolar plateau; capnography is the standard confirmation of tracheal tube placement.

Low-flow circle system

Fresh gas flow near metabolic oxygen consumption (about 5-10 mL/kg/min) with an active CO2 absorber; requires leak testing and absorber inspection before use.

Extubation readiness

Judged by return of swallowing, jaw tone, and airway reflexes with the patient able to maintain sternal recumbency; a fixed time interval is not a reliable criterion.

Anesthetic depth assessment

Composite of palpebral, laryngeal, and pedal reflexes, jaw tone, eye position, and autonomic signs; no single reflex is reliable across species or drug protocols.

Vaporizer agent specificity

Vaporizers are calibrated for one agent; using a sevoflurane-calibrated vaporizer with isoflurane delivers a concentration different from the dial setting and is unsafe.

Pulse oximetry limitation

Hemoglobin oxygen saturation reflects oxygen binding, not ventilation or perfusion; values can be normal despite hypoventilation if supplemental oxygen is delivered.

Multimodal analgesia

Combining drugs acting at different sites (peripheral transduction, dorsal horn sensitization, descending modulation) to lower individual doses and adverse effects while improving analgesia.

NMDA antagonist role

Subanesthetic ketamine (~0.5 mg/kg IV) attenuates central sensitization and opioid tolerance; it is an adjunct and not a sole analgesic.

Buprenorphine pharmacology

Partial mu agonist with high receptor affinity and a ceiling effect; slow dissociation gives long duration but limits maximal analgesia compared with full agonists.

Butorphanol pharmacology

Kappa agonist and mu antagonist with short duration; useful for mild visceral pain and sedation but weak for moderate to severe somatic pain.

COX-1 versus COX-2

COX-1 is constitutive in gastric mucosa, kidney, and platelets; COX-2 is largely inducible at inflammation sites. COX-1 sparing reduces but does not eliminate GI and renal risk.

Local anesthetic mechanism

Blockade of voltage-gated sodium channels prevents axonal depolarization; weak bases are less effective in acidic infected tissue where ionized drug cannot cross membranes.

Bupivacaine maximum dose

Approximately 2 mg/kg in dogs for infiltration or block; exceeding the limit risks cardiotoxicity, and doses must be calculated before administration.

Lidocaine maximum dose

Approximately 4-6 mg/kg in dogs for local infiltration; cumulative dose across all sites must be summed before injection to avoid systemic toxicity.

Alpha-2 agonist analgesia

Dexmedetomidine and medetomidine activate alpha-2 adrenoceptors in the dorsal horn; predictable bradycardia and vasoconstriction occur, and atipamezole reverses effects.

Tramadol mechanism

Analgesia via mu agonism plus monoamine reuptake inhibition; oral bioavailability and efficacy vary widely among species and individual patients.

Preemptive analgesia

Administering analgesia before the noxious stimulus reduces central sensitization and subsequent analgesic requirements compared with treating pain once established.

Feline Grimace Scale

Validated composite of ear position, orbital tightening, muzzle tension, whisker position, and head position used to score acute pain in cats.

Glasgow pain scale

Composite measure pain scale for dogs combining behavioral and interaction items with physiologic variables; validated for scoring acute postoperative pain.

Physiologic pain indicators

Heart rate, respiratory rate, blood pressure, and pupil size change with pain but are insensitive and nonspecific; they must be combined with behavioral assessment.

Wind-up phenomenon

Repeated C-fiber input progressively amplifies dorsal horn neuron responses, producing central sensitization and hyperalgesia that NMDA antagonists can attenuate.

Opioid ceiling effect

Partial agonists such as buprenorphine reach a maximum analgesic response; increasing dose beyond it adds duration or side effects rather than greater analgesia.

NSAID renal caution

Prostaglandin synthesis supports renal blood flow in hypovolemic or hypotensive patients; NSAIDs in these states risk acute kidney injury and should be avoided.

Constant rate infusion

Drug delivery at a fixed rate calculated as dose (mg/kg/min) times body weight divided by concentration; maintains steady plasma levels for sustained analgesia.

Maropitant antiemetic use

NK-1 receptor antagonist used perioperatively to control vomiting and visceral pain; it complements rather than replaces analgesic drugs.