Exam 2 Flashcards
(80 cards)
1
Q
Stage I & II of Anesthesia Depth
A
Stage I
• Awake
• = ventilation w/ intercostal & diaphragm
Stage II • Excitement • = ventilation w/ intercostal & diaphragm • irregular breath holding • dilated pupil
2
Q
Stage III of Anesthesia Depth
A
• Surgical stage
Light • = ventilation w/ intercostal & diaphragm • regular breathing • normal pupil • still have palpebral & corneal reflex • causes lacrimation in horses
Medium • = ventilation w/ intercostal & diaphragm • shallow breathing • semi-dilated pupil • only corneal reflex
Deep • Ventilation w/ diaphragm • Jerky breathing • Dilated pupil • small corneal reflex • only time when palpebral reflex is lost in horses
3
Q
Stage IV of Anesthesia Depth
A
- CNS & respiratory depression
- Extremely dilate pupil
- No corneal or palpebral reflex
4
Q
Occulocardiac Reflex
A
- When you put Pressure/traction on eyeball -> bradyarrhythmia
- Treat w/ atropine (or local block in horses)
5
Q
Cushing Reflex & how to treat
A
- Increase intracranial P
- Arterial hypertension, w/ compensatory bradycardia
- respiratory irregularity
- Treat w/ mannitol or hypertonic saline
6
Q
Methods for Taking Body Temp
A
o Rectal
o Esophageal
o Axillary
o Infared auricular
7
Q
Hypothermia
A
o <96.8 F o usually happens w/in 20 mins of anesthesia o decreases O2 consumption o causes peripheral vasoconstriction o compromise immune function o can impair platelets & prolong bleeding time in shock patients o decreases anesthetic requirement o delays drug elimination & recovery
8
Q
Ways a Body Loses Heat
A
o 15% thru conduction or evaporation
o 85% thru convection or radiation
9
Q
Methods to Warm Patient
A
o Warming blankets
o Heated pads
o Fluid warmers
o Heating lamps
10
Q
Methods to Avoid Hypothermia
A
o Avoid cold surfaces o Use warmed towels/blankets o Minimize scrub fluids o Gel for ECG placing o Warm fluid bags o Wrap non-clipped body parts (limbs) o Decrease O2 flow rate
11
Q
Hyperthermia; causes & treatment
A
o >104
Caused by • Malignant hyperthermia syndrome (MHS) • Infection → sepsis • Using rebreathing system with low fresh gas flow in larger-breed • Over heating
Treatment
• MHS: Stop inhalant anesthetics
• Other: ice, ventilate w/ cool air (cool air slowly)
12
Q
Anesthesia Basic Impacts on Organs
A
o Decrease Cardiac output
o Decrease oxygen delivery to all organs
13
Q
Opioids, A-2 agonists, Acepromazime, & Benzodiazepines & Cardiovascular Dz, Respiratory Dz, Hepatic Dz, Renal Dz
A
Opioids • CV - Yes! • Respiratory - Yes! • Hepatic – Yes! (reversible) • Renal – Yes!
Alpha 2 agonists
• CV- No! (Increase cardiac work & vasoconstriction)
• Respiratory - Maybe
• Hepatic – Yes! (reversible but caution in severe dz)
• Renal – Caution is Dz is severe
Acepromazine (no reversal) • CV - Maybe • Respiratory - Yes! • Hepatic – No! (hepatic metabolism) • Renal – Yes!
Benzodiazepine • CV - Yes! • Respiratory - Yes! • Hepatic – Yes! (reversible) • Renal – Yes!
14
Q
Propofol / Alfaxalone, Ketamine / Benzo / Telazol, etomidate, inhalant as
Induction Drugs & Cardiovascular Dz, Respiratory Dz, Hepatic Dz, Renal Dz
A
Propofol / Alfaxalone • CV - Yes in low Dose • Respiratory – Yes in low dose • Hepatic – Yes! • Renal – Yes!
Ketamine / Benzo / Telazol • CV – Maybe (May increase cardiac work) • Respiratory - Yes! • Hepatic – Maybe (some hepatic metabolism) • Renal – Maybe (some renal clearance)
Etomidate • CV - Yes! • Respiratory - Yes! • Hepatic – Maybe (some hepatic metabolism) • Renal – Yes!
Inhalant
• CV - No!
• Respiratory - Yes!
• Hepatic – No! (decreased respiration -> decreased hepatic O2)
• Renal – No! (decreased respiration -> decreased renal O2)
15
Q
Maintenance Dugs & CV Dz
A
o Can use inhalant
o Keep vaporizer VERY low
o Add analgesia
16
Q
Maintenance Dugs & Respiratory Dz
A
o If procedure involves airway -> CRI
o If airway not involved -> intubate & inhalant
o VERY low vaporizer
o May need to manually ventilate
17
Q
Maintenance Dugs & Hepatic & Renal Dz
A
o Inhalants - caution hypotension and Vasodilation
o CRIs – opioids
o Intravenous anesthesia w/ propofol or alfaxalone
o Local Anesthesia techniques: regional or local
o Mechanical ventilation if needed
o Blood pressure management w/ Fluids, Inotropes, vasopressors
o Reversal of agents may be needed
18
Q
What causes recovery complications
A
o Higher ASA status
o Adverse reactions to anesthesia during procedure
o Issues with the procedure; bleeding etc
o Long anesthesia
o Excessive anesthesia depth
o Cold body temp
19
Q
Prolonged Recovery form Anesthesia
A
o Maybe a complication, may just be ‘normal’
o Can reverse Alpha-2 agonists, benzodiazepines, opioids if the patient is recovering dangerously slowly or is having complications.
o Be sure to address pain!
many things other than drugs impact recovery time,
• duration of anesthesia (long anesthesia = long recovery)
• body temperature (biggest contributing factor)
20
Q
When to Extubate
A
Most Patients
• wait until they swallow and then extubate before they are awake & bite the tube!
Patients with upper airway dysfunction
• wait until they won’t tolerate the tube or until fully conscious
o Be prepared to reintubate
21
Q
4 Signs of Pain
A
Vocalization
• Often #1 sign of pain listed as indicative of pain.
• Not really very specific.
• Not useful in most large animals
Physiology
• Heart rate, respiratory rate, blood pressure, etc…
- Advantages
- Easy & inexpensive
- Change w/ stress; pain=stress
- Disadvantages
- Not specific for pain
- Change with stress; stress=stress
- Diseases and drugs can also cause changes
Changes in gate or posture
Changes in Behavior
22
Q
Best Way to Assess Pain
A
o Evaluate patient response to analgesic
o Use rapid opioids -> does behavior, posture, etc change?
23
Q
Analgesia for Discharge
A
Usually NSAIDs plus something else
• NSAIDs treat pain of inflammation
Infusions (if staying in hospital)
Opioids – efficacy & diversion concerns
• Transmucosal buprenorphine (especially in cats), simbadol
• Oral: codeine and other more potent opioids
• Transdermal: fentanyl patch
o One of the best ways to provide postoperative analgesia is to be aggressive with pain meds during maintenance & to use long duration drugs/techniques
24
Q
When to Administer NSAIDs
A
o Preemptive NSAIDs for healthy, hydrated patients undergoing brief elective procedures
o Postoperative NSAIDs for most other cases
o Postoperative does not mean post recovery
o Give injectable NSAID as surgery is finishing
o Don’t wait until the next day
25
Fasting Horses
o Overnight for 8-12hr
o May increase risk of postoperative ileus (not supported)
o Longer than 4hr increases acidity & viscosity of gastric content
26
Drugs Used for Pre-anesthetic Sedation for Horses
o Acepromazine
o Alpha-2 Adrenergic
o Xylazine
o Opioids
27
Using Acepromazine as Pre-anesthetic Sedation for Horse
* 0.03–0.05 mg/kg IV
* Block dopamine receptors in the CNS (central tranquillizing effect)
* Vasodilation resulting in hypotension (due to alpha1 blockade)
* Penile prolapse (a rare occurrence in stallions) is a dose-dependent effect
* Less tranquillizing effect in than xylazine but potently decreases MAC
28
Using Alpha-2 Agonists as Pre-anesthetic Sedation for Horse
* Xylazine, Detomidine, Romifidine
* Excellent sedative effects
* Decrease catecholamine release from central nervous system
* Somatic and visceral analgesia
* Increase urine output
* Temporary secondary AV block
Phase 1
• Reflex bradycardia
• Increase BP
• Peripheral vasoconstriction
Phase 2
• Reduction of sympathetic tone
• Bradycardia
• Decrease CO
29
Using Xylazine as Pre-anesthetic Sedation for Horse
* Maximal sedation 5 minutes after IV administration
* Lasts 30–60 minutes depending on the dose
* Horses may remain very sensitive to touch
* Pregnant mares? Yes! but Increase in uterine tone
* Reversal: Yohimbine 0.1 mg/kg
30
Using Opioids as Pre-anesthetic Sedation for Horse
* Inconsistent results in literature
* Butorphanol, Morphine
* Decrease GI motility
* Excitement/dysphoria (must combine with sedatives)
* Must administer sedative then opioid
31
Behavior of Horses when thoroughly pre-medded
* Low head carriage,
* relaxed facial muscles,
* pendulous lower lip
32
Induction Drugs for Horses
o Mix both drugs in one syringe
o Administer FULL dose
```
Ketamine
• 2.2 mg/kg IV
• NMDA receptors
• CNS anesthesia and analgesia
• Sympathetic-parasympathetic effect
• Pour muscle relaxation
```
Benzodiazepines (Midazolam- Diazepam)
• Muscle relaxation
• Effects on cardiovascular function are minimal
• Effects on respiration are minimal
33
How to Intubate a Horse
```
o Blind technique
o Lateral or sternal recumbency
o Head moderately extended
o Gag or bite block put in place
o Tongue pulled forward
o Et tube, lubricated on its outside
```
34
Problems Associated w/ Laying a Horse Down
Myopathy
• result from ischemia due to compression of blood vessels in dependent muscles
• During lateral recumbency it is common triceps myopathy
• Bilateral hindlimb lameness may occur following dorsal recumbency
Neuropathy,
• especially of peripheral nerves
• result from pressure on the nerve or stretching the nerve
35
How to Position Horse to Avoid Issues
o Padding should be 10–12 inches thick and covered with a waterproof material
o Entire body should be situated on the padding
o Lower thoracic limb pulled forward
to protect the triceps & reduce pressure on radial nerve
o Upper limbs are supported parallel to the table top
o Head in a neutral position
o In dorsal recumbency avoid long periods with the pelvic limbs in extension
36
PIVA Vs TIVA in Horses
PIVA
• Partial intravenous anesthesia
• Inhalation + sedatives, analgesics, muscle relaxants
TIVA
• Total intravenous anesthesia
• 2g of Ketamine + 500mg of xylazine + 1L of 5% guaiphenesin
37
Arteries Used for Arterial Pulse & BP in horses
o Reflects peripheral perfusion
```
Arteries Used
• Facial
• Transverse facial
• Metatarsal,
• Digital
• Coccygeal
```
Doppler
• On tail
• Measures systolic
38
Treatment of Intraop Hypotension in Horses
Inotropes
• Dobutamine infused to effect ( 0.5–5 μg/kg/min)
• Ca can be infused simultaneously (10–20 mg/kg) over the course of the surgery if the measured ionized calcium is low or likely to be low (e.g. intestinal emergencies)
Correct volume deficits
• A balanced electrolyte solution may be used alone, or combined with a colloid
• Hypertonic saline 7.5 % ( 4-6ml/kg)
Check anesthetic depth
39
Fasting for Ruminants
o Fasting and water deprivation decrease tympany and regurgitation
o Pulmonary functional residual capacity better preserved
Calves, sheep, goats, and camelids
• solids 12–18 h
• water 8–12 h
Adult cattle
• solids 18–24 h
• water for 12–18 h
Fasting of neonates is not advisable (hypoglycemia may result)
40
Vascular Access in Cows & Goats
Cows
• Coccygeal A or V
• Auricular A or V
• Jugular V
```
Goats
• Auricular A or V
• Jugular V
• Cephalic V
• Saphenous V
```
41
Vascular Access in Camelids
o Jugular V ventral to cervical vertebral transverse processes
o Jugular bifurcation at back corner of mandible
o Blood draw between bifurcation and cranial to the ventral process of the 5th cervical vertebra
o have four to five jugular venous valves that prevent flow of venous blood
42
Sedation of Ruminants with Xylazine
* much more potent in ruminants than in horses
* Dose dependent sedation
* Low doses 0.02– 0.05 mg/kg IV or IM, typically sedation without recumbency
* 0.1 mg/kg IV or 0.2 mg/kg IM will induce recumbency
```
Reported side effects
• Bradycardia
• Second degree AV block
• Hyperglycemia
• Oxytocin like effect on the uterus of pregnant cattle and sheep
• Sheep pulmonary edema
```
43
Sedation of Ruminants with Benzos & Opioids
```
Benzodiazepine
• None licensed
• Minimal CV & resp depression
• Useful w/ ketamine for muscle relaxation
• Dose varies 0.02-0.25 mg/kg
```
```
Opioids
• None licensed
• Enhance sedative effect of alpha 2
• Butorphanol: 0.02-0.1 mg/kg IV
• Morphine: 0.1-0.3 mg/kg IM-IV
```
44
Induction Meds for Ruminants
Ketamine
• Ketamine at 4.5 mg/kg IV can be used in domestic ruminants
• Usually combined with a benzodiazepine
Propofol
• Induction is smooth, as is recovery
• 4–6 mg/kg IV
• If injected too rapidly, apnea may occur
Tiletamine-zolazepam
• Elimination not uniform
• Differential clearance of the two drugs can affect recovery quality
45
Intubation Concerns for Ruminants
o If anesthetic plane is insufficient (regurgitation risk)
o Mouths do not open widely
o Intermandibular space is narrow
Camelids
• Semi-obligate nasal breathers
• Glottal folds (difficulty visualizing epiglottis)
46
How to Intubate a Ruminant w/ Laryngoscope
o Head and neck are hyperextended (orotracheal axis 180°)
o A laryngoscope with a 250–350 mm blade is required
o The epiglottis is depressed to visualize the larynx
o A guide tube or stylet can be used to facilitate intubation
o The endotracheal tube inserted into the larynx
47
How to Intubate a Ruminant w/ Digital Palpation
o The anesthetist’s hand should be in the mouth
o Locate and depress epiglottis
o Two fingers between the arytenoid cartilages
o The tube should inserted into the trachea
o If stylet needed, use equine nasogastric tube
48
Dealing with Ruminant Regurgitation During Anesthesia
o Remove ingesta from the buccal cavity
o Place a rumen tube to decrease the risk of aspiration
o Facilitate fluid drainage lowering the mouth
o Buccal lavage prior to extubation (suctioning)
49
Injectable Maintenance Drugs in Ruminants
o Recommended duration limited to 60 min
o Intubation is highly recommended
o Induction (xylazine–ketamine)
```
CRI (constant rate infusion)
• 1 liter of guaifenesin (5%)
• Ketamine (2 g)
• Xylazine (100 mg)
• Infused at a rate of 2–3 ml/kg/h
```
50
Inhalable Maintenance Drugs in Ruminants & anesthesia machine to use
o Isoflurane and sevoflurane
Small animal or human anesthesia machines
• Ruminants up to 200kg
Large animal anesthesia machines
• Cattle weighing over 200kg
51
Surgical Positioning for Ruminants
o Improper positioning and padding are associated with myopathy–neuropathy
o Adult cattle require 10–15 cm foam pads
o The dependent eye should be closed and lubricated
o The dependent foreleg is drawn cranially
o Weight of the thorax rests on the triceps
o Uppermost legs
Elevated and parallel to the table surface
o Head w/ mouth on lower plane
52
Monitoring Ruminants Under Anesthesia
Pulse
• Auricular, radial, and saphenous arteries
Mucous membranes (pink)
Capillary refill time
• should occur in 1–2 s
Respiratory system
• adult cattle 20–30 breaths/min
• calves, sheep, and goats 20–40 breaths/min
Eye position
• pupil toward rostral corner in surgical plane
MAP 70mmHg or higher
53
CV Supportive Therapy in Ruminants
o Hypotension can cause myopathy or neuropathy
Dobutamine
• Synthetic β‐adrenergic receptor agonist
• Increases myocardial contractility
• Increases heart rate at higher doses
Calcium borogluconate (23% solution)
• Increase myocardial contractility
• Can be given as a slow infusion (0.5–1 mL/kg/h IV)
• Bradycardia if too fast administration
54
Recovery of Ruminants after Surgery
o Quiet place
o Sternal position
o Extubation when laryngeal reflex returned
o If regurgitation remove endotracheal tube with the cuff inflated
Camelids are semi-obligate nasal breathers
• Confirm nasal airway after extubation
• Nasal phenylephrine 0.5 % if congestion
55
• Is Pain Ever Beneficial?
o YES!
o Acute pain causing a protective reflex is beneficial or has ‘biological value’
o ‘Physiologic’ or ‘Protective’ pain
56
• Chronic Pain
o ‘pathologic pain’
o pain without apparent biological value which has persisted
o Physical & pathologic changes in the pain pathway
o Can persist without the initial cause
o May not respond to traditional therapy
57
• Pathologic Pain
o maladaptive pain’
o ‘Unhelpful pain that tends to be out of all proportion to actual tissue damage and which persists long after the tissues have healed
58
• Causes of Chronic Pain
```
o Most common cause = osteoarthritis (OA) or Degenerative Joint Disease (DJD) in all species (at least mammals)
o Disc disease
o Nerve injury
o Laminitis
o Cancer (more in small animals)
```
59
• Where do we start to treat Chronic Pain?
```
o NSAIDs
o Analgesic
o Anti-inflammatory
o Treat pain at its SOURCE
o Mild to severe inflammation
```
60
NSAIDs for cats, horses, cows
Cats
• Metacam (1 dose only)
• Onsior (3 dose only)
```
Horses
• Flunixin meglumine
• Phenylbutazone
• Ketoprofen
• Firocoxib
• Diclofenac Sodium (topical)
```
Cows
• Topical flunixin meglumine
61
• Gabapentin
o anti- seizure drug in both humans and animals
o Also used to treat ‘neuropathic pain’
o Sedation is main ‘adverse’ effect (easy to see, can be good)
Dose for dogs & cats
• Range 3-20 (up to 50) BID-QID mg/kg
• Start with ~5 mg/kg BID
• Increase by ~25% every 3-7 days until the patient gets relief or sedate
Dose for horses
• as high as 160 mg/kg (one time) did not cause adverse effects
• Nonlinear pharmacokinetics
• Clinical dose? Not sure but don’t be afraid to escalate!
62
• Amantadine
o Originally released as an antiviral agent
o NMDA- receptor antagonist
o Same mechanism as ketamine
o Anti ‘wind-up’
63
• Adequan
o Joint health modifier
o Multimodal therapy for arthritis
o 5 mg/kg SQ twice a week x 4 weeks, once monthly thereafter
64
• Ketamine Infusion for Chronic Pain
o 0.25-0.5 mg/kg loading bolus
o 2-4 microg/kg/min for 4+ hours (as long as possible)
o Most effective duration of administration would be until obvious alleviation of pain
o Can administer with an opioid (small animal) and/or lidocaine
65
• Bisphosphonates drug name
o Tiludronate
| o normalize bone metabolism via inhibition of bone resorption
66
Normal Vitals in Rabbits
Heart rate
• 200-300 (beats/min)
Respiratory rate
• 32-60 (breaths/min)
Temperature
• 101.3 – 103.1(F)
67
Anatomical Considerations for Rabbits
o Obligate nasal breathers
o Small thorax relative to abdomen
o Do not fast
68
Vascular Access on Rabbits
```
o Jugular
o Cephalic
o Saphenous
o Auricular vein
o Auricular artery
```
69
Pre-meds & analgesia for rabbits
o High metabolic rate = higher dose than in dogs
o Acepromazine
o Midazolam
o Xylazine
o Dexmedetomidine
o Glycopyrrolate
o Atropine (usually inactivated by enzyme in rabbits)
o Opioids
o NSAIDs
70
Intubation Considerations in Rabbits
o Long narrow oropharynx
o Soft palate is long and the epiglottis is large
o Epiglottis must be displaced ventral to the soft palate
o Head and neck hyperextended
o align the larynx and trachea with oropharynx
o may use supraglottic airway device
71
Blind & Direct Visulazation Intubation of Rabbits
Blind Technique
• Sternal or dorsal position
• Head and neck hyperextended
• Introduce the ET tube into the oral cavity while listening
• Tube over the glottis (sound of air movement is the loudest)
• Rotate 180° to displace epiglottis
Direct Visualization
• Laryngoscope guided intubation
• Laryngoscope # 0-1 blade
72
Recovery of Rabbits
o Requires intense monitoring during preanesthetic and intra-anesthetic periods
o Many anesthetic deaths occur in the postanesthetic period
o Risk of obstruction, hypoventilation, and hypoxemia
o Even after extubation, deliver 100% Oxygen with face mask
o Stress-free, warm, dark, recovery cage
73
Anatomical Considerations for Ferrets
* The spinal cord can be subject to damage
* Risk heavily pregnant or lactating
* Short gastric transit time
* Fast for 3-4hrs
* Susceptible to hypothermia
* Common DCM & HCM
74
Normal Vitals for Ferrets
Heart rate
• 180–250 beats per minute
Blood volume
• 5–7% body weight
Temp
• 100 – 103 °F
PCV
• 40 – 60 %
75
Vascular Access on Ferrets
* Cephalic,
* saphenous,
* jugular veins
* tail artery
76
Intubation of Ferrets
* Direct visualization (laryngoscope)
* Local anesthetic over glottis
* 2-4 mm ET tube
77
Pre-meds for ferrets
* Ace
* Midazolam
* Medetomidine
* Dex
* Atropine
* Glyco
78
Monitoring Ferrets under anesthesia
Eye
• palpebral reflex only present at a very light plane
• Pupil diameter is difficult to assess but increases diameter at deeper planes of anesthesia
Jaw tone
• Increased at light anesthesia plane
Autonomic responses
• increased HR and BP to surgical stimuli even at adequate planes of anesthesia
Doppler
• placement on the tail (1 neonatal size cuff) with sphygmomanometer
79
Concerns for monitoring ferrets under anesthesia
* Blood pressure is difficult to accurately measure in ferrets
* Prone to significant thermoregulatory depression
* May experience severe respiratory depression when anesthetized
80
Recovery of ferrets
* Consider administration of reversal drugs
* Maintain oxygen after extubation until fully conscious
* Quiet warm place animal
* Sternal position
