medicine lecture note

1. Pre, Peri and Post-
Operative Care
ASR Certification Prep

2. Pre Operative Care
Pre-Surgical Planning:
Pre-surgery Examination & Blood work
Fasting
Set-up of prep area and operating room
Thermo regulation
Aseptic Preparation
Analgesic Regimen
Anesthesia
Aseptic Transfer to Surgical Field

3. Pre-surgery Examination
Examination should include:
Physical examination and blood work in large
animals
Check animal identification
Take and record temperature, HR, CRT, RR, BW
Check cage for signs of loose stool or vomiting
Observe animal in home cage for normal behaviors
Review animal medical record

4. Pre-surgical Fasting
Rodents & Rabbits (mice, rats, guinea pigs, hamsters,
rabbits):
High metabolic rate
No fasting prior to surgery
Rodents DO NOT have vomit reflex, no regurgitation
Monogastric animals (e.g. dogs, cats, swine):
Fast 6-24 hours prior to surgery
Ruminants (e.g. sheep, goats, cattle)
Fast for 12-36 hours prior to surgery.
Reduces fermentation in the rumen
Placing stomach tube reduces rumenal tympany.
All animals should have free access to water.
Restricting water results in dehydration and more difficult anesthesia.

5. Set-up of Prep Area and OR
Ensure prep area has:
Working heat support on table
Functioning anesthesia machine (if required)
Stethoscope
Appropriate drugs and reversal agents (analgesics and anesthetics)
Functioning monitoring equipment
Prep supplies and clippers
Vacuum
Ensure OR area has:
Working heat support on table
Functioning anesthesia machine (with ventilator)
Functioning monitoring equipment
Fluid support as needed
Emergency supplies (Ambu bag, and crash cart supplies)

6. OR Set Up

7. RECOMMENDED HARD SURFACE DISINFECTANTS
(e.g., table tops, equipment)
Always follow manufacturer's instructions for dilution and expiration periods
AGENT EXAMPLES* COMMENTS
Alcohols 70% ethyl alcohol
85% isopropyl alcohol
Contact time required is 15 minutes. Contaminated surfaces
take longer to disinfect. Remove gross contamination before
using. Inexpensive
Quaternary
Ammonium
Sodium hypochlorite
(Clorox ® 10% solution)
Chlorine dioxide
(Clidox®, Alcide®, MB-10®)
Corrosive. Presence of organic matter reduces activity.
Chlorine dioxide must be fresh; kills vegetative organisms
within 3 minutes of contact.
Glutaraldehydes Glutaraldehydes
(Cidex®, Cetylcide®, Cide
Wipes®)
Rapidly disinfects surfaces
Phenolics Lysol®, TBQ® Less affected by organic material than other disinfectants
Chlorhexidine Nolvasan® , Hibiclens® .Presence of blood does not interfere with activity. Rapidly
bactericidal and persistent. Effective against many viruses.
* The use of common brand names as examples does not indicate a product endorsement.

8. Aseptic Technique
• Preparation of the patient
Bland ophthalmic ointment to
eyes
remove hair from the surgery
site ( #40 blade, vacuum)
initial or preparative scrub
– Povidone-iodinefollowed by alcohol
rinse
– Chlorhexidine followed by saline rinse
move to surgical room / area
final surgical scrub/paint
– Povidone-iodine followed by alcohol
rinse
– Chlorhexidine followed by saline rinse
– Duraprep®, Chloraprep®
sterile draping of surgical site
 establish a sterile field

9. RECOMMENDED SKIN DISINFECTANTS
Alternating disinfectants is more effective than using a single agent.
AGENT EXAMPLES* COMMENTS
Idophors Betadine®, Prepodyne®,
Wescodyn®
Reduced activity in presence of organic matter. Wide range
of micobicidal action Works best in pH 6-7
Cholorhexadine Nolvasan®, Hibiclens® Presence of blood does not interfere with activity. Rapidly
bactericidal and persistent. Effective against many viruses.
Excellent for use on the skin.
* The use of common brand names as examples does not indicate a product endorsement.

10. Peri-Operative Monitoring
Allows:
• Adequate anesthesia.
• Adequate analgesia
• Adequate immobilization
• Early notice of trends which may develop
into life-threatening conditions

11. Checking Anesthetic Depth
• Reflexes
• Jaw tone
• Eye position, pupil size and pupillary
light response
• Heart and respiratory rates
• Response to surgical stimuli

12. Reflexes
• Palpebral (blink) - tested by lightly tapping the
medial or lateral canthus of the eye
• Pedal - Elicited by pinching a digit or footpad
• Corneal - Tested by touching the cornea with a
sterile object
• Laryngeal - Stimulated when the larynx is touched
by an object.

13. Parameters to Monitor
(every 10-15minutes)
• ECG (EKG)
• Peripheral Perfusion
• Pulmonary Monitoring
• Temperature
• Blood Pressure

14. ECG (EKG)
An EKG measures the electric currents
generated by the heart.
Monitors heart function
Continuous monitoring with an EKG allows
early recognition of electrical changes
associated with disorders of conduction in
the heart and arrhythmias that may need
to be treated.

15. ECG (EKG)
Cardiac dysrhythmias:
• Tachycardia: excessive rapidity of the heart
• Bradycardia: slowing of the heart
• Ventricular fibrillations: total disorganization of
the ventricular activity

16. ECG (EKG)
Premature ventricular contractions
(PVCs): early contraction
Heart Block: loss of or non-P-wave
associated QRS complexes
Indicate lack of electrical transmission in the
heart

17. Heart Rate
• Monitored by :
– Palpation of heart beat through chest wall
– Palpation of peripheral pulse for strength and
quality
– Auscultation of heart beat with stethoscope
– Electrocardiogram (EKG, ECG) with
continuous display

18. Know the acceptable HR for the species you are monitoring.
Bradycardia: excessive anesthetic depth, “too deep”
vagal stimulation
hypertension
hypothermia
drug effects
elevated cranial pressure
Tachycardia: inadequate anesthetic level, “too light”
pain/surgical stimulation
hypotension
hypoxemia
hypercarbia
drug effects
Heart Rate

19. Peripheral Perfusion
• Capillary refill time (CRT)
– Measures the time taken for refilling blanched
mucus membranes
– Observe the color of mucus membranes
– CRT should be 1-2 seconds and gums (when
not pigmented) should be pink
• Other sites for color are tongue, buccal mucous
membrane, conjunctiva of the lower eyelid, and the
mucous membranes about the prepuce or vulva
• Pale membranes indicate poor perfusion, blood loss,
or anemia
• Purple/blue membranes indicate cyanosis

20. Pulse Oximetry
• Measures the percentage of oxygenated
hemoglobin and heart rate
• Is broadly accurate for SaO2
• sensory probe needs to be placed on
nonpigmented area (tongue, tail, ear ,etc.)

21. Pulse Oximetry
Sensor beams infrared light through tissue and records
the absorption either of light passing through the
tissue to a receiver on the other side (transmission)
or reflected back to the sensor (reflectance)
Reflector sensor Transmission sensor

22. Pulse Oximetry
• Normally SaO2 is 80-90% in spontaneously
breathing animals and 95-100% in ventilated
animals
– Numbers reflect animal on 100% oxygen
• SaO2 readings are susceptible to lowering by
positional factors (slipping away from tissue, thick
tissue, pigment), vasoconstriction, drying of
contact surface, and confusion with respiratory
artifact
• Without pulse oximetry, early hypoxia can be
difficult to assess as cyanosis only becomes
apparent if values fall below 85% saturation.

23. Pulse Oximetry Monitors

24. End-tidal CO2 (ETCO2)
• Capnography measures ETCO2 concentration,
at the end of an exhalation
• Usually somewhat lower than PaCO2
• A PaCO2 measurement requires blood gas
analyzer and arterial blood samples.

25. End-tidal CO2 (ETCO2)
• Accuracy is subject to mechanical factors with
the breathing circuit such as volume, dead
pockets, tubing diameter, gas flow, etc.
• Animals with ETCO2 over 30-40 mm Hg will
usually breathe on their own
Low ETCO2

26. End-tidal CO2 (ETCO2)
When displayed as a capnographic waveform much
useful information may be derived such as:
“Spiky” topped waves may indicate a waking animal taking
short, sharp breaths
Plateau with a drop to the right may indicate a leak in the
circuit as the pressure of inspiration is not held

27. Respiration
• Monitored by :
Observation of chest wall movement
Observation of breathing bag movement
Auscultation of breath sounds
Audible respiratory monitor
• Respiratory volume may be estimated visually,
by reservoir bag inflation, or by using a ventilator
or ventilometer
• Normal tidal volume is 10-20 mL/kg/respiration
• Normal respiratory sounds are almost inaudible

28. Respiration
• Normal respiratory rates can vary widely
– Should be evaluated along with tidal volume and
respiratory trends
– May indicate an underlying physiologic change
– Arrhythmic breathing patterns are usually the effect of
a medullary respiratory control problem
– However, some abnormal patterns may be normal in
certain species
A Cheyne- stokes pattern is normal for horse
but could be sign of heart failure or
brain damage.
Apneustic breathing (inspiratory hold) seen in
healthy cats, dogs, and animals anesthetized
with ketamine

29. Respiration
Tachypnea: inadequate anesthetic level, “too light”, pain,
hypoxemia, hypercarbia, hyperthermia,
CSF acidosis, drug effects
Hypoventilation : Inadequate or reduced alveolar
ventilation leads to
Atelectasis : partial collapse of the lung
Periodic 'bagging/sighing' (every 5 minutes)
throughout the procedure can prevent this.
Apnea: excessive anesthetic depth, “too deep”,
hypothermia, recent hyperventilation,
musculoskeletal paralysis, drug effects

30. • Harsh noises, whistles or squeaks may indicate
narrow or obstructed airways or the presence of
fluid in the airways.
• Difficult or labored breathing may indicate the
presence of an airway obstruction.
• An abnormally low respiratory rate (<8-10 bpm)
is cause for concern. Apneic animals may need
to be manually ventilated throughout the
procedure at a rate of 8-12 bpm.
Respiration

31. • Inadequate Elimination Of C02
• Production Of C02 Exceeds Elimination
• Causes: Reduced Effective Alveolar Ventilation
from:
– Pulmonary Edema
– Pneumonia
– Airway Obstruction
– Interstitial Fibrosis
– Inadequate Ventilation
– (<20 Cm H20 Intra-alveolar Pressure)
– slow Respiratory Rate
– Hypoxemia
• Diagnosis: EtCO2 > 45 mm Hg
RespiratoryAcidosis

32. Respiratory Alkalosis
• Enhanced Elimination Of C02
• Elimination Of C02 Exceeds Production
• Causes: Increased Effective Alveolar
Ventilation
From:
– High Intra-alveolar pressure
– Hyperoxemia
– Hypotension
– Pulmonary edema
– Interstitial fibrosis
– Endogenous catecholamines (from stress)
– Mechanical ventilation
• Diagnosis: EtCO2 < 35 mm Hg

33. Ventilation
• Pressure is introduced into the trachea which
inflates the lungs.
• Causes a significant loss in lung compliance
• Necessary in all procedures in the thoracic
cavity.
• Ventilation can be severely compromised by
pneumothorax, hemothorax, hydrothorax or a
diaphragmatic hernia.
• Routine manual “bagging/sighing” of the
patient can prevent atelectis.

34. Body Temperature
Anesthetized animal lose the ability to
thermoregulate normally.
– Will lose heat via loss of hair to shaving, the evaporation of
prep solutions, evaporation at and chilling of tissues within
surgical incisions, and vasodilatation caused by anesthetic
agents/adjuncts
– Hypothermia will prolong anesthesia recovery
• Should be countered with warmed fluids, heating blankets, and
towels/wraps
– Hyperthermia is also possible and dangerous
• May be due to overheating with heating pads and tables or due to
anesthesia reactions such as malignant hyperthermia in swine
Anesthetized animals lose the ability to thermoregulate normally

35. Body Temperature
Monitor Temperature throughout surgery
Ways to prevent Hypothermia
Keep animal warm during induction
Warm IV Fluids and irrigating solutions
Circulating warm water/air blankets
Pad between animal and metal table
Hot water bags/bottles wrapped in towel
Covering feet, hands, paws, & head
Heat lamps

36. Blood Pressure
BP = hydrostatic force that blood exerts on wall of
vessels
Systolic Pressure= pressure of blood when
ventricles at maximum contraction
Normal range 100 to 160mmHG
Diastolic Pressure= pressure of blood when
ventricles relax
Normal range 60 to 100mmHg
MAP= (2 x DP) + SP divided by 3
Normal range 80 to 120mmHg
Pulse Pressure= systolic – diastolic
Normal ~ 40mmHg

37. MAP < 60 mmHg is hypotension
• Decreased perfusion due to low BP can cause tissue
ischemia
– Susceptibility of tissue to ischemia depends on metabolic rate of
the tissue
Hypertension: Systolic >180 mm Hg and
Diastolic >110mm Hg
• Inadequate anesthesia, partially or fully occluded airway
Controlling Blood Pressure:
anesthetic level
IV fluids
Body temperature
Blood Pressure

38. Blood Pressure
Noninvasive/Indirect- accurately reflects trends
Oscillometric method Ultrasonic Doppler

39. Blood Pressure
Invasive/ Direct – accurate quantitative
value
Arterial catheter connected to pressure
transducer

40. Immediate Post-operative Care
• Move the animal to a warm, dry area and monitor
vital signs every 15 minutes until the animal is
sternal.
• Turn side to side frequently to prevent pooling of
fluid in recumbent side.
• Remove endotracheal tube when
swallowing/chewing this prevents regurgitation and
vomiting.
• Do not return to home cage until able to maintain
body temperature and hold itself in sternal
position.

41. Post-Operative Care
A ”stormy “ recovery could be related to surgical
pain.
All animals subject to major surgery must have
analgesic agents (i.e. painkillers) available to
them for at least the initial 24-48 hours post-
surgery
Provide analgesics as directed by veterinarian.

42. Daily evaluation parameters:
appearance
attitude
appetite
Hydration
TPR
Signs of pain
Surgical Incision - for clinical signs of
infection, seroma, hematoma,
suture breakdown, wound
dehiscence.
Post-Operative Care

43. Administration of drugs
– SID or QD once daily
– BID twice daily
– TID three times daily
– QID four times daily
Suture/Staple Removal
The goal of the staples / sutures are to keep
the skin margins closed.
Evaluate incision healing prior to removal
Normal removal time is 10 to 14 days
Post-Operative Care

44. References
• NIH website http://oacu.od.nih.gov/ARAC/surguide.pdf
• Duke University Animal Care and Use Program
http://vetmed.duhs.duke.edu/guidelines_for_general_surgery_in_animal
s.htm
• Doctors Foster and Smith Website
http://www.peteducation.com/article.cfm?c=0+1302+1478&aid=977
• http://www.ruralareavet.org/PDF/Anesthesia-patient_Monitoring.pdf