Surgery 2 Flashcards
Hoof bandage
Can be wet or dry
After surgical procedures-softening
Extends under fetlock
3-5 days
Distal limb bandage
Surgical sites or intraarticular injections
From coronary band to carpus or tarsus
Fixed to hoof capsule by impermeable tape
Robert-Jones bandage
Immobilization of the limb and joints!
Standard bandage with additional sheet cotton
1.5x the circumference of the limb
Split can be applied to strengthen
Carpal bandaging
From coronary/fetlock to above the carpus
Hole/pressure releasing pads over acc carpal bones to prevent pressure sores or pressure necrosis of skin
Normal bandage plus strengthening additional layers
Splints can be applied for more restriction of movements
Carpal splint
When need stabilization of the limb- luxation, fracture, tendon rupture
On top of Robert-Jones
Proper protection of acc!!!
Split from coronary band/fetlock to under the elbow
Tarsal bandaging
Same as carpal but this time pressure releasing pads over the common calcaneal tendon
Common problems of bandages
Slipping/rotation of bandage and splint Too tight or too loose Pressure necrosis of skin Uneven tension of bandage Contamination
What is neuroleptanalgesia
sedatives and analgesic
for standing position procedures and diagnosis
head comes down to carpal level- head support may be needed
Partial unconsciousness and muscle relax– can add analgesia for surgical procedures
Combos for neuroleptanalgesia
ACP and Butorphanol
Xylazine and Butorphanol
Detomidin and Butorphanol
ACP and Xylazine and Butorphanol
Cardiopulmonary effects of alpha2 agonists
- Vagal tone incr– bradycard– decr CO
- Hypertension at beginning.. then hypotension
- if give IV– temp grade I and II AV block
- Dysrhythmia or arrhythmia
- Central resp depression
GI effects of alpha2 agonists
Block the swallow reflex
Reduced visceral motility and perfusion to the organs
Hyperglycaemia
Are good visceral analgesics– therefore good for colic
Cardiopulmonary effect of opioids
Resp depression
Hypotension
Bradycardia
Opioid drugs used: agonists
Methadone: 3-4x more potent than morphine
Morphine
Morphinum hydrochlorium
Fentanyl- lipophilic so use a patch
Opioid drugs used: agonists-antagonist
Butorphanol
Pentazocin
Opioid drugs used: antagonist
Naloxon
Nalorphin
Local anaestheisa: physical methods
Ties and tourniquets: nerve press and anaemia
Cool: at 4degrees- stops the potency of nerve stim
Local anaesthesia: chemical
Esters: cocaine, procaine and tetracaine.. are hydrolysed by plasma pseudo-cholinesterase
Amides: lidocaine, mepivacaine and bupivacaine- are metab by the liver and so are better
Cannot be absorbed through intact skin
Local anaesthetic used in optho
Oxibuprocaine and proparacaine
These are 10-15x more effective than procaine
Can be toxic for the corneal epithelium
Local anaesthetics for mucus membranes and skin
Lidocaine: most stable, good penetration: 1.5-2hrs
Bupivacaine: 4-6 hrs
Mepivacaine: fast effect! only lasts 1-2hrs
Methods of local anesthesia
Topical Infiltration Regional IV Intrasynovial Perineural Paravertebral Epidural
Local anaesthesia: Infiltration
Safest
2% lidocaine
SE: hematoma
Local anaesthesia: Regional IV
IV catheter and Esmarch tourniquet
2% lidocaine (same as for infiltration)
Local anaesthesia: Intrasynovial
Intraarticular
Intrathecal bursa
Tendon sheath: Mepivacaine, bupivacaine, lidocaine
Local anaesthesia: Perineural uses and types
Lameness diagnosing
Palliative- laminitis hoof cast
Surgery of the head
Periorbital
Dental and muzzle
Corneal
Local anaesthesia: Paravertebral anaesthesia
Laparoscopy and flank laparotomy
If successful block– vasodilation, sweating– Horner’s syndrome like
Local anaesthesia: Epidural
Sedation Btw Cc1 and Cc2 Drugs used: 2%lidocaine Xylazine (and saline) Detomidne and morphine Morphine
ASA classification of risk categories for surgery
- Healthy horse
- Mild systemic disease– mild anemia, RAO
- Severe systemic disease– severe RAO
- Severe systemic that is life-threatening– colic, polytrauma
- Moribound horse, not expected to survive for more than 24hrs– foal with uroperitoneum
E. Emergency
Preoperative evaluation
Goal: to define the risk for the owner
To select the best strategy to minimize the risks
- Free airway- intubation
- O2 supply
- IPPV= intermittent Postive Pressure Ventilation
- Venous Pressure Catheter
- CPR= cardio pulmonary resuscitation
Patient prep for surgery
- History- prev anaesthesia
- Physical exam- focus on resp, CV, musculoskeletal and CNS
- For emergency cases- first treat shock and stabilize
- Lab tests: elective selection: PCV, TPP sometimes hematology
- Fasting– no water for 6 hrs prev–lung function, decr chance of stomach rupture and decr risk of postop ileus
- Body weight- drug dosages
Surgical Complications and emergencies
Cardiopulmonary resuscitation Anaphylaxis Intraoperative hypotension During maintenance Hypoxemia and Hypoxia Hypercapnia Postop myopathy Postop neuropathy Postop laryngeal edema
Cardiopulmonary resusitation
Intraop mortality 30% due to cardiac arrest
Caused by deep hypotension and the anesthesia
Signs: EtCO2 decreases Weak pulse Cyanotic mm Dilated pupils Kussmaul type breathing
Tx: discontinue anesthetic admin IPPV Chest compression 60x/min O2 supply IV drugs
Anaphylaxis
Causes:
vasoD and incr vessel permeability
AB’s- penicillin and aminoglycosides
Just after drug admin there is: spO2 decr, weak pulse, bronchospasm, pulmonary edema
Tx: Stop giving the drug IPPV O2 Give epinephrine, AH's etc
Intraoperative hypotension: what it is and causes:
Happens with inhalational more so than TIVA or PIVA
Make sure ABP is over 70mmHg, foals should be lower
Myocardial depression- endotoxaemia
Bradycard
Hypovolemia, acidosis and electrolyte imbalance–shock
Intraoperative hypotension: consequences
Poor tissue perfusion Postop myopathy SC ischaemia Cerebreal necrosis Myocardial dysfunction
Intraoperative hypotension: treatment
Infusion– electrolyte, colloid, hypertonic
(+)inotrop– dobutamin
calcium
During maintenance
hypovent– V/Q mismatch– hypoxemia
decr CO
Hypoxemia and hypoxia: what it is and causes
Hypoxemia: paCO2 is less than 60mmHg
Hypoxia: inadequate tissue oxygenation
Causes: Failure in O2 supply Hypoventilation Problems with endotracheal tube Distended abdomen putting pressure on thorax RAO Acute pulmonary edema Shunt
Hypoxemia and hypoxia: Methods of improving
Early vent–IPPV
Increase FiO2
Albuterol bronchoD
Pulsed delivered NO
Hypercapnia: What it is, causes, effects and treatment
When paCO2 is greater than 45mmHg
Causes:
Resp centre depression
Hypovent
Incr CO2 prod
Effects:
Symp stim
Arrhythmia, resp acidosis
Intracranial P incr
Tx:
IPPV– get to anesthesia depth
Postop myopathy: causes and treatment
Causes: Large body Long anesthesia time Inadequate padding Intraop hypotension and hypoxemia
Tx: Adequate padding Assistance in standing Mild cases- exercise and walking Mannitol infusion Vit E and selenium Massage
Postop neuropathy
Caused by inadequate padding and conditioning, overextension of limbs
Radial, femoral and facial nerve injury
Treatment similar to myopathy
Postop laryngeal edema: what it is, causes and treatment
Spinal cord myelomalacia– very severe
in young- hypotension, embolus
“dog-sit position- loss of deep pain- poor prognosis
Cerebral cortical necrosis- severe and fatal
Causes:
Bilateral nasal/ laryngeal edema
Bilateral laryngeal neuropathy- hemiplagia
Negative pressure pulmonary edema
Tx:
Temp tracheostomy
Anesthesia of risk patients: foals– considerations
Pulm changes within the first few hours
Circ changes within 3 days
PaO2 is less in lateral recumbency (10-15mmHg) than it is in standing– provide O2 if in lateral recumbency
Lung and chest compliance is less than in adult
Anesthesia of risk patients: foals- preoperative evaluation
Congenital heart defect very high risk because the ductus arteriosus can reopen- hypoxemia or acidosis
Colostrum intake- measure IgG- if less than 800mg/dl- give plasma infusion or colloids
Blood glucose- hypoglycaemia- not sucking, bacteremic
Anesthesia of risk patients: foals– fasting
Neonatal- allowed to suck
If tube fed- withold milk- sick foals have delayed gastric emptying
Foals over 3 months- max 4-6 hrs fasting
Anesthesia of risk patients: foals- Newborns thermoregulation
CO2 production is HR dependent so avoid bradycardia
Small body mass, low fat, large surface area leads to significant heat loss
High metabolic rate- leads to hypoxia and hypoglycaemia faster than it would in adult horses
Effects of hypothermia: decr MAC bradycard and decr CO decr perfusion decr metab incr bleeding time delayed recovery with incr O2 consumption
Anesthesia of risk patients: foals- sedation
T=Young easily become recumbent
Have to prevent hypotension and hypoglycaemia
Always provide O2!!!
Drugs:
Butorphanol
BZD: diazepam midazolam give exact dose IV
Xylazine and detomidine- only to not critically sick and older- because of the CV SE’s
Medetomidine and romifidine IV
All low doses to effect
Avoid giving in the sick neonatal foal
Drugs to neonatal foals
Injectable Considerations: High sensitivity of receptors High TBW and plasma fluid Permeable BBB Low albumin therefore low plasma protein binding .. but weaker drug metabolism-- longer lasting effect Inhal can have a lower MAC
Anesthesia of risk patients: foals– Induction
INHALATIONAL ANESTHETICS ARE NOT RECOMMENDED
In neonates after minimal sedation
Facemask/ nsotracheal tube
Very quick uptake of these drugs
With IV Drugs:
Light plane: ketamine and xylazine
Deep plane: ketamine and xylazine and alpha2 agonist
Propofol on its own
Anesthesia of risk patients: foals– maintenance
Inhal or TIVA or PIVA
PIVA: ketamine, isoflurane and lidocaine
Anesthesia of risk patients: foals– Monitoring
They have a lower blood pressure
bradycardia <50 beats
High RR- this is why the inhal an are very rapidle acting
Endotracheal intubation difficult– therefore easier to get hypercapnia
PaCO2 is less than 50-60mmHg- small volume breathing circle needs to be used
Active heating
Check blood glucose– give IV dextrose if very low
During recovery get to sternal recumbency ASAP because of the compliance of thorax
Anaesthesia of Geriatric Horse: general considerations
Over 20 years of age Loss of functional reserve Lower ABP Lower ventricular filling Lower TBW Lower metab, liver, kidney and heart function
Anaesthesia of Geriatric Horse: sedation
ACP IM and xylazine and butorphanol IV
Anaesthesia of Geriatric Horse: anesthesia
Not a good option
Inhal, TIVA, PIVA– IPPV is essential
Preferred: Neurolept- analgesia and local anesthetics– in standing position
Anaesthesia of Geriatric Horse: monitoring
positioning body temp thermoreg decr ABP supporting- hypovol ECG dysrrhythmias Blood gas analysis
Anaesthesia of Geriatric Horse: some age associated diseases
RAO
Cushings
Aortic valve insufficiency
Hypothyroidism
Recovery with assistance
Anaesthesia of donkeys and mules: general considerations
Narrower, deeper larynx and trachea– smaller ET
Jugular catheterization is more difficult
Faster elim of drugs- therefore more freq dosing needed– around 30% higher than for a horse
Plasma GGT is 3x greater than horses
Sedation: IM first then give IV alpha2
Anaesthesia of donkeys and mules: maintenance
TIVA: triple drip: alpha2 and ketamine and GGE- small donkeys can be easily OD, GGE sensitivity- hemolysis
PIVA
Inhal an
NSAIDS- shorter elim half life than horse
Opioids
Prone to hypoxemia
Anaesthesia of horses with intestinal emergencies (colic): general considerations
10x greater risk–which is multifactorial- CV compromise and endotoxemia
Anaesthesia of horses with intestinal emergencies (colic): Preop Evaluation
Hypovolaemic shock: HR, Pulse and CRT all incr
cyanotic and pale mm
Abdominal pain, shock- stomach and intestinal distension
Endotoxaemic shock
Anaesthesia of horses with intestinal emergencies (colic): Preparation
- Stomach tube- for better resp and CV function
- Fluid therapy:
Isotonic fluids– maybe intestinal edema and reflux
Hypertonic saline
Colloids
Acid-base correction
Anaesthesia of horses with intestinal emergencies (colic): Sedation and analgesia
Xylazine NSAIDS Opioids can combo with alpha2 agonist Antiendotoxin like polymixin B ABx- penicillin or gentamicin before induction
PHENOTHIAZINES ARE CONTRA!!
Anaesthesia of horses with intestinal emergencies (colic): Maintenance and recovery
IPPV- can actually further compromise CV
give low dose Isoflurane, make sure there is adequate oxygen
PIVA: Lidocain CRI
If theres hypocalcaemia give Dobutamine in an infusion slowly with calcium
Recovery is usually slow
Anaesthesia of pregnant mare: general considerations
Paramount to maintain BP and normal O2
Minimal surgery time– minimize the fetal exposure
Big belly presses against thoracic cavity- intraop hypovent and hypoxemia– IPPV is therefore NB!!!
Anaesthesia of pregnant mare: sedation
alpha2
opioids– but they can cross the placental barrier
Flunixin can block PGF2alpha release- ensures fetus is not lost after uterine manipulation
Anaesthesia of pregnant mare: Maintenance
Inhal:
isoflurane
half-lateral recumbency to avoid v.cava compression
TIVA can cause fetal bradycard if continuously given
PIVA lidocaine can be toxic
Anaesthesia of pregnant mare: Monitoring
ABP
Blood gas analysis
Fetal HR
If doing C-section- give oxytocin to prevent blood loss
Trendelenberg position- worst position for pregnant mare becuase put more P on the thorax
Anaesthesia of pregnant mare: Recovery
Myopathy: because large body, hypotonia and hypoxemia
Mare is exhausted so needs assistance
Fracture risks: so calcium decreases
Hyperkalemic periodic paralysis (HYPP)
Signs and treatment
GA can act as a trigger Signs: Hyperkalemia Tachy/ bradycardia ECG changes Hypotension Muscle tremor Hypercapnia Normothermia
Treatment: Ca-gluconate infusion Dextrose inf insulin all act to move K out of blood into the IC space
Anaesthetic and equine malignant hyperthermia
Freq: QH’s, thoroughbred, appaloosa, arabian, pony
When an. for more than 3hrs
ETCO2 incr PaCO2 incr Muscle rigidity Tachpnea Body temp incr 2nd metab acidosis- arrhythmia, CK and K incr
Mechanism: the volatile anesthetic stim Ca release from the SR into the myoplasm– muscle contration– heat and acid prod
Tx:
Pure O2 IPPV
TIVA and good monitoring is preferred
Dantrolene to block the calcium release
Anaesthesia of horse with RAO:
Prior to surgery: Secretolytic and bronchodilator Inhal an: IPPV and O2 supplementation is essential Longer insp and exp phase- defective elastic recoil- airway closure Albuterol into ET- Ventolin spray
Anaesthesia of horse with CV problem
Rare!! is usually secondary
Anaesthesia Practice- principles
Physical exam Catheter site Lavage of oral cavity Premed Induction Intubation Reflexes in surgery-plane Recovery
Anaesthesia Practice: physical exam
CV and resp systems!!! Heart beat auscultation at least 5 mins on both sides ]Auscultate lungs both sides RR and quality of breath Intestinal- colic Conjunctiva and mm CRT in the mouth Core temp
Anaesthesia Practice: Catheter site
Clipping
Clean with soap
Disinfection with alcohol containing solutions
No LA or sedation to be used through it
Secure with one-stitch suture- short term
Anaesthesia Practice: premedication drugs
IM in semitendinous muscle
IV for sedative e.g xylazine
Anaesthesia Practice: Reflexes in surgery plane
Remains:
Corneal reflex
Ventromedial rotated eyeball
Pupillary light reflex
Gone:
Palpebral reflex
Nystagmus
Tears
Anaesthesia Practice: recovery
Stop inhal an and disconnect the breathing circuit
Move to recovery box
ET remains with the inflated cuff- give O2 and then remove it
Cover shoes with tape
Keep in lat recumbency for as long as possible
Anaesthesia practice: IPPV
Volume icr– injury to lung
Pressure incr– less injury to lung
small: 10 H2Ocm
large: 20 H2Ocm
Anaesthesia practice: TV
In generak 10ml/kg bw, for a thin horse it is more
Anaesthesia practice: O2 consumption
Minimum 2-3ml/kg
Types of narcosis systems
Open
Semi-open
Semi-closed
Closed
Narcosis system- open
No
- rebreathing balloon
- CO2 absorption
- re-breathing
Narcosis system- semi-open
Yes- rebreathing balloon
No- CO2 absorption
Partial- rebreathing -pendulum like cyst
Narcosis system- semi-closed
Yes
- rebreathing balloon
-CO2 absorption
Partial- rebreathing
Narcosis system- closed
Yes
- rebreathing ballon
- CO2 absorption
- rebreathing
Anaesthesia machine: components
Mixing part Breathing circle Endotracheal tube IPPV (when is it indicated) Monitoring
Anaesthesia machine: Mixing part
Gas source Regulator and reductor valves, manometer Flow meter: l/min- max is 10l/min O2 flush valve/bypass Vaporiser= out of circuit
Anaesthesia machine: Breathing circuit
Y-shape rebreathing hoses
Rebreathing balloon/bag- needs to be at least 2x thhe TV
CO2 absorber- sodalime or sodium and Calcium hydroxide
Pop-off valve
Central scaveneger apparatus and tube
One- way inhal and exhal valves
Anaesthesia machine: Endotracheal tubes
Cuffed silicone
Bifurcation at shoulder joint
Anaesthesia machine: IPPV and when is it indicated
When RR <2-6/min Large abd volume causes dyspnoea Open thorax surgery Resp acidosis Hypoxemia nd hypercapnia
It is a pressure limited ventilator- insp pressure should reach 20 H2Ocm at the end of inhalation, at expiration should be >0 H2Ocm
Volume/time limited
To return to spontaneous at the end of IPPV: decr iso and incr O2– and watch capnogram
Anaesthesia machine: Monitoring
Eye Pulse MM Breathing frequency and quality ECG RR Pulsoximetry <90%--- IPPV Capnography: ETCO2> 45Hgmm-- hypercapnia Blood gas analysis- use arterial sample: pH <7.35-- acidosis (ABE < 2.5) PaCO2 > 45mmHg-- resp acidosis-- hypercapnia HCO3 < 20mmol/l-- metabolic acidosis
If ABP > 70mmHg- give Dobutamine
Stages and planes of GA
I stadium analgesiae II stadium excitationis III stadium tolerantiae III/1 superf III/2 surgical- this is the one that has to be reached III/3 deep III/4 stadium paralyticum
General anaesthesia: CV system- ECG
Rate and rhythm
Leads: Left- caud to olecranon and electrode
Right: caud to olecranon
Neutral: on loose skin on chest
General anaesthesia: CV system– heart rate
Normal: 35-45/min
brady < 25/min
tachy > 55/min
Frequency largely determines CO
General anaesthesia: CV system– causes of bradycardia
Dtugs: alpha2, opioids, OD any anaesthetic
Increased vagal tone
Metabolic: hypotherm, end stage hypoxaemia, hyperkalemia
Heart diseases
General anaesthesia: CV system– causes of tachycardia
Light level of anaesthesia- slight nociception during surgery
Drugs- ketamine
Metabolic- hypovolemia, hypoxemia, hypercapnia
Endocrine- pheochromocytoma, hyperthyreoidosis
Heart diseases
General anaesthesia: CV system– Blood pressure
Indirect: not useful in horses but maybe in foals, on forelimb and tail
Direct:
Facial, transv facial and metatarsalis
Normotension
systolic: 90-130 mmHg
diastolic: 60-90 mmHg
mean: 70-110 mmHg
Hypotension
When systolic is under 80mmHg and /or mean is under 60 mmHg– compromised cerebral and coronary perfusion
Hypertension
When systolic pressure is above 180mmHg and/or mean pressure above 140 mmHg– edema and bleedings in the brain and lungs
General anaesthesia: Resp system– changes
Apnea- can even occur during light anaesthesia
Bradypnea– deep anesthesia hypothermia
Tachypnea– occurs during light due to hypoxemia, hypercapnia, atelectasis airway obstruction
General anaesthesia: Resp system– pulse oximetry
Measures HB oxygen saturation, emits red and UV light
Normal: 98-99%
Hypoxaemia: < 95%
Severe hypoxaemia: < 90%
General anaesthesia: Resp system– partial pressure of oxygen in the arterial blood (PaCO2)
Determined by blood-gas analysis Normal: 80-110 mmHg Hypoxaemia- anything under 80 Severe life-threatening hypoxaemia under 60 mmHg Hyperoxaemia- above 110mmHg
General anaesthesia: Resp system– Capnography
Uses infrared light absorption technology- can be side-stream or mainstream CO2 of exhaled air End tidal CO2 partial pressure/conc Resp status Ventilation Perfusion Metabolism
General anaesthesia: Resp system– Temperature
Hypothermia is not a big issue because of the large size, but may be an issue for foals
