Pre, Peri and Post-Operative Care

ASR Certification Prep

Pre Operative Care

Pre-Surgical Planning:Pre-surgery Examination & Blood workFastingSet-up of prep area and operating roomThermo regulationAseptic PreparationAnalgesic RegimenAnesthesiaAseptic Transfer to Surgical Field

Pre-surgery Examination

Examination should include:

Physical examination and blood work in large animals

Check animal identificationTake and record temperature, HR, CRT, RR, BW

Check cage for signs of loose stool or vomitingObserve animal in home cage for normal

behaviorsReview animal medical record

Pre-surgical Fasting

Rodents & Rabbits (mice, rats, guinea pigs, hamsters, rabbits): 

High metabolic rateNo fasting prior to surgeryRodents 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 rumenPlacing stomach tube reduces rumenal tympany.

All animals should have free access to water. Restricting water results in dehydration and more difficult anesthesia.

Set-up of Prep Area and OR

Ensure prep area has: Working heat support on tableFunctioning anesthesia machine (if required)StethoscopeAppropriate drugs and reversal agents (analgesics and anesthetics)Functioning monitoring equipmentPrep supplies and clippersVacuum

Ensure OR area has: Working heat support on tableFunctioning anesthesia machine (with ventilator)Functioning monitoring equipmentFluid support as neededEmergency supplies (Ambu bag, and crash cart supplies)

OR Set Up

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.

Aseptic Technique

• Preparation of the patient Bland ophthalmic ointment to

eyesremove 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

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.

Peri-Operative Monitoring Allows:

• Adequate anesthesia.

• Adequate analgesia

• Adequate immobilization

• Early notice of trends which may develop into life-threatening conditions

Checking Anesthetic Depth

• Reflexes

• Jaw tone

• Eye position, pupil size and pupillary light response

• Heart and respiratory rates

• Response to surgical stimuli

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.

Parameters to Monitor(every 10-15minutes)

• ECG (EKG)

• Peripheral Perfusion

• Pulmonary Monitoring

• Temperature

• Blood Pressure

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.

ECG (EKG)Cardiac dysrhythmias:

• Tachycardia: excessive rapidity of the heart

• Bradycardia: slowing of the heart

• Ventricular fibrillations: total disorganization of the ventricular activity

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

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

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

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

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.)

Pulse OximetrySensor 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

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.

Pulse Oximetry Monitors

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.

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

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

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

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

RespirationTachypnea: 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

• 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

• 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

Respiratory Acidosis

Respiratory Alkalosis• Enhanced Elimination Of C02• Elimination Of C02 Exceeds Production• Causes: Increased Effective Alveolar

VentilationFrom:– High Intra-alveolar pressure– Hyperoxemia– Hypotension– Pulmonary edema– Interstitial fibrosis – Endogenous catecholamines (from stress) – Mechanical ventilation

• Diagnosis: EtCO2 < 35 mm Hg

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.

Body TemperatureAnesthetized 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

Body TemperatureMonitor Temperature throughout surgery

Ways to prevent HypothermiaKeep 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

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

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

Blood PressureNoninvasive/Indirect- accurately reflects trendsOscillometric method Ultrasonic Doppler

Blood Pressure

Invasive/ Direct – accurate quantitative value

Arterial catheter connected to pressure transducer

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.

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.

Daily evaluation parameters:appearance attitude appetite HydrationTPRSigns of painSurgical Incision - for clinical signs of infection, seroma, hematoma,

suture breakdown, wound dehiscence.

Post-Operative Care

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

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_animals.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