Be your clinic’s “go to” Anesthesia Technician

2. Be your clinic’s “go to” Anesthesia Technician Chad R. Brown, DVM Assistant Professor of Veterinary Technology Mountwest Community & Technical College

3. After 15 years of general mixed practice and 4 years in academia, It is my opinion…….

4. That most anesthesia problems and deaths are our faults!

5. Role of the Veterinary Anesthetist Minimum patient database Proper patient fasting Preinduction patient care All supplies are available All equipment is in working order Preanesthetic medication

6. In a perfect world…… It is imperative for the anesthesia team to have a working knowledge of anesthetic and analgesic drugs, including advantages, disadvantages and potential side effects.

7. In a perfect world….. The team should also be aware of anticipated or potential complications based on the patient status, underlying disease, procedure and drug selection and have a plan of action should they occur, without compromising patient safety.

8. Minimum Patient Database (MPD) Patient history Physical examination and assessment Preanesthetic diagnostic workup

9. Patient History—Signalment Species Species have unique responses to anesthetic agents Horses and cats—opioids Dosing requirements Recovery—horses Anticholinergics avoided in ruminants Ventilation support—large animals Excess airway secretions—cats and ruminants Exotic animals are handled differently

10. Patient History—Signalment (Cont’d) Breed Differences in anatomy and physiology Sighthounds—sensitive to barbiturates Boxers and giant breeds—sensitive to acepromazine Terriers—resistant to acepromazine Brachiocephalic dogs—difficult to intubate Draft horses—sensitive to sedatives

11. Patient History—Signalment (Cont’d) Age Plays a factor in drug choice Neonates and pediatric patients Geriatric patients

12. Patient History—Medications Current or past May influence effect of anesthetic agents Sympathomimetics Tricyclic antidepressants Antibiotics Monoamine oxidase inhibitors Antihistamines

13. Patient History—Past/Current Illnesses Preexisting disease Anorexia, vomiting, diarrhea, coughing, sneezing, polyuria, polydipsia, tenesmus, dysuria General signs of illness Stabilized prior to anesthesia Change in behavior CNS disorder Pain Systemic illness

14. Patient History—Past/Current Illnesses (Cont’d) Exercise intolerance Heart disease Anemia Musculoskeletal pain Weakness A nonspecific sign Fainting or seizures Often difficult to differentiate Have different etiologies

15. Past History—Past/Current Illnesses Unexplained bleeding Bruising Blood in feces or urine Prolonged bleeding after injury Associated with coagulation disorders Increased risk of intra- and postoperative hemorrhage

17. Physical Status Classification Classification is based on an evaluation of the Minimum Patient Database Rates patient anesthetic risk American Society of Anesthesiologists Class P1 = minimal anesthetic risk Class P5 = extreme anesthetic risk Classes P1 and P2 use standard anesthetic protocol Classes P3 to P5 need special protocols and stabilization

18. Anesthetic Protocols Established by the veterinarian Factors considered Facilities and equipment Familiarity with anesthetic agents Nature of the procedure Circumstances specific to a procedure Cost Urgency

19. Fluid comparison

21. Fluid Selection Healthy animal undergoing routine surgery Isotonic, polyionic, replacement fluids Sick patients PCV =>20, TP =>3.5 g/dL Isotonic, polyionic replacement fluids

22. Administration Rate During routine anesthesia and surgery SMALL and LARGE ANIMAL dose 10 mL/kg/hr during the first hour 5 mL/kg/hr during remainder of the procedure

23. Fluid Administration Rate—Isotonic Crystalloids Excessive hemorrhage or hypotension 40 mL/kg/hr (dogs and large animals) – maximum of 1 hr 20 mL/kg/hr (cats) Shock 90 mL/kg/hr as rapidly as possibly (dogs and large animals) 55 mL/kg/hr as rapidly as possible (cats) Shock and blood loss (large and small animals) 7% hypertonic saline 3-4 mL/kg slowly over 5 minutes Followed by isotonic crystalloid solution

24. Fluid Administration Rate—Colloids 10-20 mL/kg/day (dogs and large animals) 5-10 mL/kg/day (cats) Monitor to prevent overload, coagulation disorders, and allergies Administer as a slow bolus Over 15-60 minutes (dogs and large animals) Over 30-60 minutes (cats)

25. Ideal Objectives of Surgical Anesthesia Patient doesn’t move Patient isn’t aware Patient doesn’t feel pain Patient has no memory of the procedure

26. Assessment of Anesthetic Depth To make sure the patient is at a depth that provides immobility, unconsciousness, and lack of awareness of pain while avoiding conditions that endanger the patient such as hypoventilation, hypoxemia, hypotension, and hypothermia.

28. Assessment of Anesthetic Depth: Reflexes An unconscious response to a stimulus Conscious animals and protective reflexes Decreased reflexes to stage III, plane 3 level anesthesia (when there are few to none) Reflexes evaluated Swallowing, laryngeal, pedal, palpebral, corneal, papillary light reflex Reported as present, decreased, or absent

29. Palpebral reflex • The blink reflex in response to a light tap on the medial or lateral canthus • May be elicited by lightly stroking the hairs of the upper eyelid • Present in light anesthesia • Often lost during medium anesthesia, although the exact point varies • Slow palpebral response in horses indicates adequate surgical anesthetic depth

30. Swallowing Reflex A normal response to food or saliva in the pharynx Monitored by viewing the ventral neck region Present in light surgical anesthesia Lost in medium surgical anesthesia Returns just before the patient regains consciousness Used to determine when to pull the endotracheal tube

31. Laryngeal Reflex Epiglottis and vocal cords close immediately when larynx is touched by an object Prevents tracheal aspiration Observed during intubation if animal is in the light plane of anesthesia Makes intubation difficult Especially in cats, pigs, and small ruminants May cause laryngospasm in cats, pigs, and small ruminants

32. Corneal Reflex • Retraction of eyeball within orbit and/or a blink in response to corneal stimulation • Touch the cornea with a drop of sterile saline or artificial tears • Most useful in large animals; difficult to elicit in small animals • Present in light and medium anesthesia; absent in deep or excessive anesthesia • Used primarily to determine if a LA patient is too deep

33. Pedal Reflex • Flexion or withdrawal of limb in response to squeezing, twisting, or pinching a digit or pad • Used in small animals only • Varies from subtle muscle contraction to full withdrawal of limb • Varies with depth of anesthesia • Present in light anesthesia • Absent in medium anesthesia • Requires a high intensity stimulus

34. Pupillary Light Reflex (PLR) Constriction of pupils in response to bright light shined on one retina Present in light and medium anesthesia; absent in deep anesthesia Dazzle reflex Blink response to bright light shined on retinas Same significance as PLR Lost very early in anesthesia

35. Other Indicators of Anesthetic Depth Spontaneous movement Muscle tone – jaw, anal tone Eye position – central(light and deep), ventro-medial(medium) Pupil size – mydriasis(stage II), miotic (light) Nystagmus – horses – fast(light), slow (medium) Salivary and lacrimal secretions – decrease with deeper anesthesia Heart and respiratory rates – not good indicators of depth Response to surgical stimulation

36. Stage I Period of voluntary movement Patient begins to lose consciousness Characterized by: Fear, excitement, disorientation, struggling, urination, defecation Increased heart rate and respiratory rate Stage ends with loss of ability to stand and recumbency

37. Stage II Period of involuntary movement; the “excitement stage” – they can hurt themselves or the anesthetist Characterized by: Breathing irregular Vocalization, struggling, paddling Increased heart and respiratory rate, pupils dilated, muscle tone marked, reflexes present Actions are not under conscious control Stage ends with muscle relaxation, decreased respiratory rate, and decreased reflex activity

38. Stage III Period of surgical anesthesia Divided into four planes Plane 1: not adequate for surgery: Regular respiratory pattern, no involuntary limb movements Eyeballs start to rotate ventrally, pupils partially constricted, decreased pupillary light reflex Endotracheal tube may be passed and connected to gas anesthetic machine Other reflexes are still present but decreased response

39. Stage III Plane 2 Suitable depth for most surgical procedures Characterized by: Regular and shallow respiration with decreased rate Blood pressure and heart rate mildly decreased Relaxed muscle tone Pedal and swallowing reflexes are absent Ventromedial eye rotation

40. Stage III Plane 2 (Cont’d) Surgical stimulation may produce: Mild increase in heart rate, blood pressure, or respiratory rate Patient remains unconscious and immobile Pupillary light response is sluggish; pupil size is moderate

41. Stage III Plane 4 Early anesthesia overdose Characterized by: Abdominal breathing Fully dilated pupils; dry eyes All reflexes are absent Marked depression of the cardiovascular system, pale mucous membranes, increased CRT Flaccid muscle tone

42. Stage IV Period of anesthetic overdose Characterized by: Cessation of respiration Circulatory collapse Death Resuscitate immediately to save the patient

43. Stage III in 3 Planes Alternative classification Plane 1: “light” surgical anesthesia Not suitable for surgery Plane 2: “medium” surgical anesthesia Optimum depth for most surgical procedures Plane 3: “deep” surgical anesthesia Excessive depth

44. NEED A FORM for anesthetic depth inserted here

46. Which style of anesthesia monitoring do you use? • Have Amanda take a pic in anesthesia monitoring with only a pulse ox, checking facebook, no masks, eating something

47. Why are we trained to use these?

48. Great RVT’s know the normal values of each line

49. BUT….!!!!! A well-trained, educated, sensitive, alert technician is the best monitor.