Which of the following species is commonly associated with the manifestation of malignant hyperthermia during an anesthetic event?
Correct Answer: C
Malignant hyperthermia is most commonly associated with people and swine. Malignant hyperthermia, also known as Porcine Stress Syndrome (PSS), occurs commonly in pigs and is associated with an autosomal recessive gene that predisposes them to manifest clinical signs of the syndrome in times of stress when given gas anesthetics or other medications. It can cause: *Muscle and tail tremors *Dyspnea *Blanching alternating with reddening of the skin *Hyperthermia *Cyanosis *Muscle rigidity *Death Once signs become evident, treatment includes: *Removal of the stress *Applying external cooling *IV dantrolene sodium blocks the sarcoplasmic reticulum's calcium release from skeletal muscles, causing muscle relaxation. Classified as a skeletal muscle relaxant, it is the only treatment available to date for the disease.
Question 167
When using ocular signs to monitor anesthetic depth, which patient response describes a present palpebral reflex?
Correct Answer: D
A brisk palpebral reflex is consistent with a lighter anesthetic plane. It will progressively become slow, weak, and absent as depth increases. The term "palpebral" refers specifically to the eyelids and does not involve the globe or cornea, as referred to in the other answer options. Tapping the skin medially or laterally by the canthus induces this response. When assessing eye position, rotation of the globes ventromedially is an indicator of intermediate anesthetic depth. Fixation of the pupils centrally and dilated indicates a deep plane. Blinking or retraction of the globe when the corneal surface is in contact is called the corneal reflex; its loss indicates a late sign shown with a deep anesthetic plane.
Question 168
When developing an anesthetic plan for a 1-hour procedure, all of the following would be examples of commonly used drug combinations for TIVA for a horse, except for which of the following?
Correct Answer: B
TIVA, or total intravenous anesthesia, allows general anesthesia sans inhalant. Rather than maintain an animal on gas such as isoflurane and provide intermittent boluses of IV anesthetics/sedatives such as xylazine or ketamine intraoperatively, all injectable medications are used. Combinations commonly used for TIVA include a dissociative such as ketamine with a variety of alpha2-agonists +/- guaifenesin, ketamine, and a benzodiazepine or a propofol CRI or intermittent boluses of propofol. Ketamine alone would be insufficient for total anesthesia because, while it provides some somatic analgesia, it does not produce any muscle relaxation, simply a state of immobilization or catalepsy. When given alone, it can increase the risk of excitement on recovery or induce prolonged or unreliable recoveries. When used alone, dissociatives do not produce a state of general anesthesia and thus, would not be sufficient for a TIVA protocol. Additionally, dissociatives increase muscle tone and sensitivity to sound and light, maintain intact reflexes, and can increase both heart rate and blood pressure. By giving other medications, you can balance out these effects to reach a normal steady-state for the heart and body.
Question 169
Which medication is effective in the management of moderate levels of pain?
Correct Answer: B
Buprenorphine is a partial mu agonist which provides mild to moderate pain relief for six to eight hours with typical dosing. NSAID medications, such as meloxicam, can treat low to moderate levels of pain associated with inflammation or prostaglandin production. Butorphanol is a mixed agonist-antagonist used to treat mild levels of pain of short duration and, more commonly, used for its sedative effects. Ketamine is a dissociative best used in conjunction with other analgesics to prevent wind-up (central-sensitization).
Question 170
What is the optimal level of anesthesia for most invasive surgical procedures?
Correct Answer: A
During stage III, the animal loses pain sensations. Some reflexes are inhibited, while necessary bodily functions continue. Stage III is divided into light stage III, surgical, and deep stage III. These planes correspond to inadequate, optimal, and excessive depth of anesthesia. Stage II, the excitement stage, refers to the point at which the animal begins breathing irregularly and no longer has voluntary control. Here we may see vocalization or paddling. Stage II, medium plane, is an incorrectly used combination of terms. Stage III, deep stage anesthesia, is incorrect because this level of anesthesia is where the patient is almost at the point of not breathing and should be avoided.
