Final: Chemical Restraint and sedation for minor procedures, Anesthetic considerations for trauma patients and C-sections, Common misconceptions in anesthesia Flashcards
Chemical restraint and sedation for minor procedures
Which drug has a dose dependent length of action that provides good analgesia and sedation in dogs and cats but is short in horses?
Dexmedetomidine
Chemical restraint and sedation for minor procedures
Which drug becomes valuable in fractious or angry patients?
Ketamine
it can be asborbed transmucosally.
Thay also respond well to alfaxalone
Chemical restraint and sedation for minor procedures
What drugs do you use for sick patients? what drugs do you only want to use in healthy patients?
Benzos, alpha 2s
Chemical restraint and sedation for minor procedures
Which drug is discouraged in small animals? What is a go to sedation combination in our small and large animal species?
avoid xylazine
SA: alfaxalone and dexmedetomidine
LA: telazol, ketamine, dexmedetomidine or BAM (butorphanol, azeperone, medetomidine)
Anesthetic considerations for trauma patients
What abnormalities are associated with lung contustions?
Affect oxygenation and ventilation: Prone to atelectasis, Hypoxemia/hypoventilation, Depending on severity
May require IPPV, BUT….
Risk for barotrauma/pneumothorax
Low peak insp. pressures (↑ RR)
PEEP (positive end-expiratory pressure)
Anesthetic considerations for trauma patients
What abnormalities are associated with (TENSION) pneumothorax?
What happens to circulation?
atelectasis, hypoxemia
decreased lung compliance, sudden drop in BP (decreased venous return), CV collapse
TENSION pneumothorax: entrapment of air compressing on things in thorax
Anesthetic considerations for trauma patients
What abnormalities are associated with diaphragmatic hernia?
Decreased FRC (functional residual capacity), atelectasis, hypoxemia
Anesthetic considerations for trauma patients
What abnormalities are associated with myocardial contusions?
What drugs do you want to avoid?
Arrhythmias
VPC, may be worse with anesthesia, treat if it is compromising circulation (O2, fluids, analgesia, lidocaine)
Preop ECG
Avoid arrhythmogenic drugs (alpha 2 agonist, thiopental, halothane)
Anesthetic considerations for trauma patients
What abnormalities are associate with hemorrhage?
How will it effect drug uptake? why?
Hypovolemia, hypotension
Anemia, hypoproteinemia (decreased oxygen delivery, reduced drug binding)
Anesthetic considerations for trauma patients
What abnormalities are seen with a ruptured bladder?
a COMMON occurence*
Uroabdomen, azotemia, decreased Na and Cl, increased K
Hyperkalemia is the most severe, raises resting membrane potential, life-threatening arrhythmias.
Prolonged PR, tented T waves, loss of P waves, widening of QRS, v-fib/asystole
Anesthesia can worsen arrhythmias, have a continuous ECG, normalize K before anesthesia, catheterization (drain urine), supplement with Ca++, sodium bicarb, insulin/dextrose
Anesthetic considerations for trauma patients
What abnormalities are seen with head trauma?
What drugs do you want to avoid?
Increase in intracranial pressure, mentation/ pupil size, cushing’s reflex (hypertension and bradycardia), changes in breathing pattern
Anesthesia can alter blood flow to brain: intubation can spike ICP (lidocaine lowers ICP), IA affects cerebral autoregulation, PaCO2 needs to be maintained WNL (PPV), avoid drugs that increase ICP
Ketamine increases ICP
Propofol and alfaxalone comes with hypotension and apnea but decreases ICP
Anesthetic considerations for trauma patients
What are some neuroleptoanalgesics we use in our veterinary species?
CV sparing drugs…
Opioids and sedative/tranquilizer
Fentanyl and midazolam/diazepam
CV sparring (etomidate?): Etomidate and midazolam/diazepam is the most CV and respiratory sparing. Good in cats (HCM), short immunosuppression, remember to dilute etomidate due to hemolysis.
Use Anticholinergic if there is bradycardia (atropine, glycopyrrolate)
Anesthetic considerations for trauma patients
What do consider for maintenance and continuous infusions?
balanced anesthesia, easily titratable, reduce MAC
Continuous infusions with: opioids, low dose ketamine, low dose lidocaine (not for cats, increased sensitivity and negative cardiovascular effects), regional anesthesia
Anesthetic considerations for c-section and neonates
What are some physiologic changes and perioperative concerns during pregnancy?
cardio changes, respiratory changes, amount of anesthesia, GI
increased blood volume, plasma greater than RBC, can be seen as “anemic”
a pregnant uterus displaces the abdomen, O2 consumption increases by 20% (ventilation, TV, RR). increased progesterone increases sensitivity to PaCO2 (Preoxygenate!!)
anesthetic requirements decrease 25-40%, there is a high risk of overdose
GI changes, emptying, regurge
Anesthetic considerations for c-section and neonates
What are the basic anesthetic protocols to maintain?
Maintain BP, avoid rapid desaturation (hypoxemia), correct electrolytes (Ca++), minimize doses
Anesthetic considerations for c-section and neonates
(LA and SA) What kind of drugs do you want to use?
premed, induction, maintenance and post op
Reversible or short acting, minimize CV effects, pros and cons to premeds, local anesthesia, titrate drugs carefully.
Premeds
SA: opioids and anticholinergics.
LA: alpha 2 agonists
Ruminants: benzos or no premedication
Induction IV only (mask induction too long and stressful)
Propofol or alfaxlaone preferred in small animal. Etomidate or fentanyl in special cases.
Ketamine and propofol (benzo) in LA
Give time (about 15 minutes) for drug induction
Maintenance IA, avoid nitrous oxide, low dose, with local anesthetic
Post op: incision block, morphine epidural, systemic opioids, NSAIDs
Anesthetic considerations for c-section and neonates
What is the care involved for a neonate post c-section?
Should have one person for every neonate.
Resuscitation: Clear oropharynx of secretions. Antagonize drugs. Rub chest vigorously to stimulate respiration. Intubate if not breathing. Acupuncture at GV26 (at the nose to stimulate breathing)
Doxapram is controversial, increases O2 consumption but not if the patient is already hypoxemic.
Anesthetic considerations for c-section and neonates
What are some anesthetic concernc for the neonate post c-section?
Decreased ability to metabolize drugs (low liver enzymes), hypoglycemia (again with the liver, low glycogen stores, want to maintain glucose >70 mg/dl), hypothermia (greater surface area to body weight), bradycardia (immature sympathetic nervous system. Avoid bradycardia, anticholinergics if necessary), hypotension (want MAP>50 mmHG), this is less than an adult, ephedrine if it gets too low), hypoventilation (they have increased thoracic compliance and weak muscles) > which makes them susceptible to atelectasis.
if drugs cross BBB, they cross the placenta
Common misconceptions in anesthesia
What are some anesthetic considerations for our greyhound breeds?
With Thiobarbiturates, they have a delayed recovery (3-4x) longer and because of their lower liver enzymes, they do not metabolize the drugs as rapidly.
Hyperkalemia: etiology is unknown and is often subclinical but it can be life-threatening.
Their mutant DEPOH gene makes them prone to bleeding disorders and post-operative hemorrhage. There is hyperfibrinolysis; antifibrinolytic drugs help.
Common misconceptions in anesthesia
What are some anesthetic considerations for our collie breeds?
what about in cats?
The MDR1 genes in collies (first identified with ivermectin) (shelties, Aussie shepherds, and whippets) predisposes them to prolonged sedation as this is the gene that provides a functional p-glycoprotein which is needed for the BBB. So, may want to avoid acepromazine and butorphanol.
Also, have a MDR1 mutation. Experience neurotxicity with eprinomectin. Seen in NON-PURE bred Maine coons.
Common misconceptions in anesthesia
T/F you should not use acepromazine in Boxers ever
Acepromazine increases vagal response and can lead to collapse. But have been used without issues, use with caution.
Common misconceptions in anesthesia
Myth: a strong pulse indicates good blood pressure and tissue perfusion
What is the truth?
A strong palpable pulse just means the difference between systolic and diastolic pressures, it does not rule out hypotension. Not only old and sick patients get hypotensive during anesthesia, many young and healthy, too. Decrease anesthetic depth, give a bolus of IV fluids and inotropes. Can only tell a patient is hypotensive if you measure it*
