Pre-surgical evaluation

1. Pre-surgical evaluation • 1. Reasons for a pre-surgical evaluation. • Diversity • of individuals of differing age, breed, species • and their varied reactions to different anesthetic protocols resulting in • different risks necessitating • different choices based on the • individual patients and their • individual needs.

2. Pre-surgical evaluation • Minimum Data base. • Patient history • procedure to be performed • complete physical exam • diagnostic tests requested by supervising veterinarian including radiography, electrocardiography, u/a, hematology, serology and others. • Determination of patient risk in consultation with the vet.

3. Pre-surgical evaluation • History questions: Why? • 1. Procedure. Don’t want to euthanize an animal in for a spay. • 2. Age- geriatrics require special attention and workup. • 3. Previous illness. May affect response to anesthetic chosen • 4. Recent illness in last day.- may affect anesthetic response. • 5. Exercise tolerance. May indicate anemia or heart disease.

4. Pre-surgical evaluation • History questions: Why? • 6. Recent drugs or chemicals. Affect metabolism. • 7. Allergies or drug reactions. Anaphylaxis cautions. • 8. Last vaccine. May be susceptible to disease in clinic. • 9. Reproductive status. Female in heat shouldn’t be spayed. • 10. Any symptoms of seizures, fainting, bleeding, xs thirst, or difficultly urinating or defecating?

5. Pre-surgical evaluation • Summary of take home message. If you short cut your procedures when it comes to anesthesia it will come home and “bite you on your backside”. • Laziness and inattention to detail can lead to DEATH!!!

6. Physical examination • Physical examination major components • Signalment (Age, breed, sex, weight, species) • Disposition & Activity level. Is he BAR, depressed, painful, viscous, etc.

7. Physical examination • Physical examination major components • Examination of Organ Systems. • Include: overall body condition, temperature, head, pupillary light reflex, heart and lung auscultation, compare pulse to heart rate, determine respiratory rate, examine skin and coat, examine for pain and lameness, palpate lymph nodes, abdominal palpation, check mammary glands.

8. Physical examination • Physical exam in order that makes sense to you: • mouth, gums, teeth, eyes, ears, chest and abdomen, limbs, tail, claws, heart, lungs, temperature, anal sacs. • Just make sure you develop a technique which prevents you from missing something.

9. Physical examination • Diagnostic test: Information provided • CBC anemia, infection, allergies, et al • u/a kidney, liver, hydration, et al • serum chemistry organ function, hydration, nerve electrolytes function, et al • clotting tests healing function et al • blood gases ability to transport O2and CO2 et al • ECG heart function, electrolytes et al • radiography organ function, tumors, et al

10. Practical Application Activity • Make a “ patient history form” and put it in your black book for future reference. • Make a pre-surgical screen form and put it in your black book

11. Fasting • Pre-anesthetic fasting • Prevents regurgitation of stomach contents during induction, surgery or recovery resulting in aspiration pneumonia. • If unfasted, we can induce vomiting with apomorphine (dogs) or xylazine (cats) or premedicate with antiemetic like acepromazine • If we can’t induce vomiting, make sure patient is intubated with cuff inflated. • Monitor patients closely during induction and recovery to assist in keeping airway open during twilight stages. • Can make young animal hypoglycemic so we fast puppies and kittens less time

12. Fasting • Timeframe for fasting

13. Fasting • Don’t withhold water from dehydrated patients. First start them on IV to re-hydrate • Vomiting • anti-emetic pre-anesthetic like acepromazine • use of cuffed endotracheal tube • pre-med with an emetic before anesthesia • GIT surgery. Withhold food 24 hours and water 12 hours. Give pre-op enema. Should be on IV fluids with dextrose when possible to maintain strength and prevent protein catabolism.

14. Fasting • Precautions before GIT surgery • no food 24 hours/ no water 8 hours before stomach surgery. • One or more enemas within 12 hours of colon surgery.

15. Fasting • Fasting contraindications • when animal is • too sick • too painful, • too frightened, or • too weak to eat for an extended period before the surgery.

16. Contraindications to Fasting • Cachexia • prolonged anorexia • hypoglycemia in toy puppies • diabetes • other digestive disturbances

17. Benefits to IV line • 1. Allows safe use of irritating IV anesthetic • 2. Simultaneous injection of incompatible drugs. • 3. Rapid administration of emergency drugs. • 4. Allows administration of balanced electrolytes during surgery • 5. Allows constant infusion of drugs like antibiotics. • 6. Easier to administer anesthetics to effect.

18. Safe fluid administration rates • Routine Anesthesia- 10 ml/kg/hr • Cardiovascular or renal disease. 5ml/kg/hr • bleeding or hypotensive • 20 ml/kg/1st 15 minutes • 3 ml of fluid/ ml of blood lost • shock • up to 90 ml/kg/hr in dog • up to 70 ml/kg/hr in cat

19. IV catheter • Benefits of intra-venous catheter • safe use of anesthetic agents that are irritating perivascularly, • allow simultaneous injections of 2 drugs that cannot be mixed together • rapid and easy administration of emergency drugs. • Allows administration of iv fluids • for use on animals that require continuous infusion of drugs or electrolytes. • Easier to give pentobarb and propofol which are dosed to effect.

20. Signs of an over-hydrated patient • Ocular discharge • nasal discharge • chemosis (swelling of conjunctiva) • increased lung sounds • increased respiratory rate • Dyspnea • Others?

21. Types of IV fluids (page 23) • Lactated ringers (not that expensive) • Balanced and complete for acidotic animal • Must have functional liver to convert lactate • Saline 0.9% (isotonic) • dextrose for debilitated, young, and diabetic • 2.5 % • 5.0 % • Colloid • Blood and plasma • Synthetic (hetastarch) • Blood substitute like oxyglobin

22. Practical Application Activity • Add the charts from page 11 of your course pack to your black book. • Drip rate calculations for a 23 Kg dog with a 15 gtt/ml drip set. • standard sx. = 1 drop/sec • bleeding = 2 drops/ sec plus 3 ml fluid/ml blood lost • shock = 9drops/sec

23. Pre-anesthetic agents • Read pages 25 through 47 of text • 4 reasons for using a premed • a. calm or sedate excited or viscious animals • b. Reduce or eliminate bad side effects of anesthetics. • c. reduce amount of general anesthetic • d. Decrease pain and discomfort post-op

24. Pre-anesthetic agents • Contraindications to pre-med • TIME- in an emergency • ALLERGY-Adverse patient history with pre-med • contraindications based on patients physical status.

25. Categories of Premeds Anticholinergics or Parasympatholytics • drugs that counteract the parasympathetic nervous system like atropine or glycopyrrolate • They give the sympathetic system free rein Sedatives • phenothiazine- acepromazine • benzodiazepene- valium • thiazine- xylazine Analgesics- to relieve post op pain They are more effective given before pain occurs -morphine, butorphenol, and oxymorphone

26. Anticholinergics

27. Glycopyrrolate • Lasts 2 times as long • affects heart rate and rhythm less • suppresses salivation more completely • more expensive

28. Atropine contraindications • High heart rate • dogs 140 bpm • cats 160 bpm • Congestive heart failure • constipation or ileus

29. Sedatives • Phenothiazines • no respiratory depression • minimal cardiac problems • good sedation • anti-emetic effect • anti-dysrhythmic effect • anti-histamine effect • peripheral vasodilator • reduces threshold for seizures - careful with epileptics • occasionally excitatory rather than sedating- can make an anxious animal viscious

30. Sedatives • Benzodiazepenes • anti-anxiety and calming effect (not sedating) • skeletal muscle relaxation • anti-convulsant drug of choice for seizure patients that should be used for premedication. • contraindicated in neonates and liver disease • best given iv slowly (fast iv causes bradycardia) • can be mixed with opiods for smooth induction

31. Sedatives • Thiazines • sedation and analgesia and muscle relaxation • decreases anesthetics up to 50-80% • Analgesic effect 16-20 minutes • adverse effects • Bradycardia and second degree heart block • some respiratory depression in some animals • vomiting 50% dogs 90% cats • bloating in ruminants and dogs • hepatic function important for normal recovery • profound sleep in some animals • reduces insulin secretion from pancreas • reversal with Yohimbine

32. Opiods • Opiod vrs. Narcotic…. both pain killers but narcotics are addictive. • CNS depression or excitement depending on the drug and the patient. Cats esp. weird. • Greatest useful effect is analgesia • main adverse effects in vet patients are respiratory depression, bradycardia, hypotension, vomiting and constipation. • Reversed by naloxone. esp useful in capture of wild animals when given the hypnotic dose of drug.

33. Post-op pain relief with opiods • Best given in advance of pain rather than after pain has occurred. • Gov’t regulation requires narcotic logs and triple prescription pads.