Day 3 - anaesthesia Flashcards
Risk factors of an.
Age
Type of surgery (fracture and colic)
Body position
Premedication (use acepromacine!)
Duration
Time of an
Provide .. to anaesthesia
- Free airway (intubation)
- O2 supply
- IPPV (intermittent positive pressure ventilation)
- Venous access-catheter
- CPR=Cardio-Pulmonary Resuscitation
Prior to sedation; give .. (4)
Antimicrobials
Anti-inflammatories
IV. Catheter in jugular vein
Flushing the oral cavity with tap water
Drugs for premedication (4)
Phenothiaxines (Acepromazine)
Alpha2 adrenergic drug
Opioids (never alone, cause excitement)
Benzodiazepines (young foals)
Combinations of premedications (4)
o Alpha2- agonists
o Alpha2agonists + Phenothiazine/opioid
o Phenothiazine + alpha2- agonist/ + opioid
o Benzodiazepine (neonates)
Drugs for induction
Ketamine
Guaiphenesin (GGE)
Barbiturates (thiopental – best choice (short acting))
Propofol
Example of premedication (4)
- Ketamine + Diazepam
- GGe: + Ketamin or + thiopental
- Tiletamine + zolazepam, not narcotic drug
- Propofol
- Inhalational anestetics (foal)
Maintanance of an (3)
LEARN THE INFO
TIVA (total intravenous anesthesia)
Inhalational anesthesia
PIVA (Partial intravenous anesthesia) (balanced an.)
TIVA advantages/disadv
ADV:
* Less depression on cardioresp.
* TIVA stress < inhalation anesthesia
* Good analgesia
* Less complication/mortality
* Nice recovery
* Min. tissue toxicity
DISADV.:
* drug accumulation, infusion pump is needed
* Methods of drug delivery:
o Intermittent injection (bolus)
o Drip technique (infusion/syringe pump) – continus infusion
TIVA 2 groups
1ST GROUP: SHORT ANESTHESIA (<30 MINS)
Alpha2-agonist (1/4 dose) + dissociative anesthesia (1/2 dose) –> 5-10 min
Thiopental
2ND GROUP: MID LONG ANESTHESIA (30-60 MINS)
Hypoxia can develop, give extra O2, Boluses/CRI (continuous rate infusion)
TIVA combinations (3)
- Triple drip in CRI
- GGE 5% + xylazine + ketamine
- Ketamine + Xylazine + diazepam
Inhalation an
- Adv/disadv
- Drugs
ADV:
* Depth can be changed rapidly
* Can be monitored
* Min. drug accumulation
* Elimination is ventilation dependent
DISADV:
* Pollution
* Cardiorespiratory depression
* Min. analgesia
* Expensive
* Recovery is not as good as TIVA
MAC- minimal alveolar concentration
1. Isoflurane (MAC: 1.31%)
2. Sevoflurane (MAC: 2.31%)
3. Desflurane (MAC: 7.6%)
PIVA
Combined use of inhalational and intravenous anesthesia
Adv/disadv
ADV.
* Cardiorespiratory depression decrease (MAC decr.)
* Analgesia increase
* Organ toxicity decrease
* Movement decrease
* Recovery increase
* Mortality decrease
* Muscle-relaxing effects of inhalational anesthesia
DISADV.
* Pollution
* Cardiovascular depression ßinhalation drugs
* Equipment: IV + inhalation drugs
* Long procedures
IV drugs accumulation
PIVA - drugs (5)
- Ketamine
- Alpha2-agonist:
- medetomidine
- Romifidine
- Xylazine - Ketamine + alpha2-agonists
- Lidocaine – colic patients in continuous iv drip
- Lidocane + ketamine - approx. 60% - colic patients
Fluid loss - replacement
Replace fluid loss: 5-10 ml/kg/h
Methods to decrease surgical stress (3)
- Increase tissue perfusion: avoid hypotension, hypovolemia (circulatory system)
- Local anesthesia: prevent nociceptive signals to CNS
- Butorphanol: decrease cortisol response
Recovery
Use of part-dose of alpha2-agonists in recovery, keep in lateral recumbency, dark, quiet box, urethral catheters
Complications and emergencies (8)
- Cardiopulmonary resuscitation
- Anaphylaxis
- Intraoperative hypotension
- Hypoxemia and hypoxia
- Hypercapnia
- Postoperative myopathy
- Postoperative neuropathy
- Postoperative laryngeal oedema
Resuscitation drugs (4)
Vasoconstriction - epinephrine
Positive ionotrop - dobutamine
Vagolytic - atropine
Ventricular tachycardia - lidocain
Treatment of anaphylaxis
IPPV
Ventilate with O2
Fluid therapy
Give: epinephrine, bronchodialator, corticosteroids, antihistamines
Check ABP, ECG
Treatment of intraoperative hypotension
- Hypotension
- Poor tissue perfusion
- Postop myopathy
- Spinal cord ischemia
- Cerebral necrosis
- Myocardial dysfunction
- Treatment
Infusion: electrolyte/colloid/hypertonic
+ inotrope: dobutamin
Preoperative evaluation - important things - ana of foals
-Auscultation on heart
-Congenital cardiac
-Heart murmur
-Colostrum intake
-Blood glucose
-Substitute glucose
Effects of hypothermia - ana of foals
-MAC ̄
-Bradycardia – decreased CO
-Tissue perfusion ̄, metabolism ̄, bleeding time
-Delayed recovery, increased O2 consumption (shivering)
ana of foals - sedation
-Diazepam, midazolam
-Prevent: hypothermia, hypoglycemia!!
-Provide extra O2!!!
-Butorphanol
-Benzodiazepines: diazepam/diazolam – Safest combo! -Exact dose, careful IV injection, dilute!
a2 agonists: (over 4 weeks, not so sick)
-xylazine
-detomidine
-medetomidine
-romifidine
Induction with inhalation - ana foals
not recommended
Induction with IV - ana foals
Light plane anesthesia/short (eg. joint lavage):
-Ketamine + diazepam
Deep plane an./long
-Ketamine + diazepam +/- a2 agonist -Propofol (apnea, minimal analgesia)
Ana geriatic horse - sedation
Acepromacine, Xylazine, butorphanol
Age restrictive diseases - ana (4)
RAO
Cushing syndrome
Aortic valve insufficiency
Hypothyroidism
Ana of colic horses - preop
-Hypovolemic shock
-Abdominal pain-shock
-Endotoxemic shock
1. Stomach tube
2. Rapid fluid therapy
-Isotonic fluids
-Hypertonic saline
-Colloids
-Acid-base correction: metabolic acidosis (mixed)
Ana of colic horses - sedation, analgesia
-a2 agonist: xylazine
-NSAIDs (antiendotox-flunixin, analgesic)
-Opioids: with a2 agonist combo
-Phenotiazines contraindicated!! Don’t for shock patients!
Anti-endotoxin: polymixin B, anti-endotoxin serum, flunixin, DMSO
AB: b-lactam (penicillin) + aminoglycoside (gentamicin) before induction
Ana of preggo - maintanance
inhalation, isoflurane
ANESTHESIA AND HYPERKALEMIC PERIODIC PARALYSIS
Hyperkaema
Tachy/bradycardia
ECG changes
Hypotension
Muscle tremor
Hypercapnia
Normothermia
Tx: Ca-gluconate inf., Dextrose inf., insulin (K+) ̄ IV
ana of cardiovascular horse
-Hypovolemic shock (severe hemorrhage)
-Endotoxemia, sepsis (colic)
-Profound electrolyte imbalance
-Stabilize prior to an.!
-Low doses of sedatives, pre-emptive analgesic drugs
Induction: GGE/benzodiazepins + ketamine
Balance an., monitoring: ABP, ECG, blood gas
IPPV
-increase volume
-increase pressure
Volume increase – injury to lung Pressure increase – less injury to lung
Tidal volume
10 ml/kg for a 500kg horse 5 liter
O2 consumption
Average: 5ml/kg/minute for a 500kg horse 2,5 liter/minute
Monitoring during general anaesthesia
Physical signs
ECG
Blood pressure
Pulse- oximetry
Capnography
Blood gas analysis (additional) Other (eg. EEG, not often)
Depths og anaesthesia (3)
- Stadium analgesiae
- Stadium excitationis
- Stadium tolerantiae
Leads of ECG
o Positive electrode on the left thorax, caudal to the olecranon
o Negative electrode on the right thorax, caudal to the olecranon
o Neutral electrode to the loose skin about the junction of the neck
HR of horses
- Normal: 35 – 45/min
- Bradycardia: < 25/min
- Tachycardia: > 55/min
Causes of bradycardia
- Drugs: alfa2 agonist, opioid agonist, overdose of any anesthetics
- Increased vagal tone: ETT, abdominal nociception, traction of ocular muscles, high blood pressure
- Metabolic: hypothermia, end-stage hypoxemia, hyperkalaemia
- Heart disease
Causes of tachycardia
- Light level of anesthesia: nociceptive response during surgery
- Drugs: ketamine, parasympatholytics, sympathomimetics
- Metabolic: hypovolemia, hypoxia, hypercapnia, hyperthermia, postoperative pain
- Endocrine disorders: pheochromocytoma, hyperthyreoidosis
- Heart disease
Hypotension - causes and consequences
Causes:
o Hypovolemia
o ̄ cardiac output
o Vasodilatation
Consequences
o Compromised cerebral and coronary perfusion
Hypertension - causes and consequences
Causes:
o Vasoconstriction
Consequences (acute):
o Edema and bleeding in organs (brain, lungs)
Capnography
- Non invasive
- Monitoring the cardiopulmomary system
- Lot of information:
o Carbon dioxide content of exhaled gas
o End tidal carbon dioxide partial pressure/concentration
o Respiratory status
o Ventilation
o Perfusion
o Metabolism
Normal EtCO2: 35- 45 mmHg
ALPHA2 ADRENERGIC RECEPTOR AGONIST
Sedative effect, muscle relaxation, analgesia (visceral). Side effect: peripheral vasoconstriction, reflex bradycardia, bradyarrythmias.
Xylasine
Detemodine
Romifidine
NSAIDS
Anti-inflammatory, Antipyretic, Painkiller
Side effects
o GI ulcer, GI bleeding
o Nephrotoxic
o Hepatotoxic
o Antithrombotic effect
o Chondrotoxic
- Ketoprofen (foal)
- Flunixin melgumine (Visceral pain, inflammation, potent COX inhibitor, tissue irritant)
- Phenylbutazone: Orthopaedic pain, muscle and skeletal disorders. SE: Gi problems, tissue necrosis
- Meloxicam, foals
- Firocoxib
- Diclofenac
NMDA RECEPTOR ANTAGONISTS
Ketamin
Anaesthetic and maintenance, analgesic properties
Increased heart rate, cardiac output, arterial blood pressure
Opioids
Excitement, agitation, increased locomotor activity, BUT calming. In combo w/ alpha2-a.
- Butorphanol: in combo
- Buprenorphine: In combo
- Morphine
- Methadone
- Fentanyl
