Goals Epidural anaesthesia Mechanical ventilation Cardiopulmonary rescucitation
Why administer an epidural analgesic? Gold standard pain relief for hind limb surgery, single injection lasts for 18-24 hours Low adverse reaction risk Cheap Simple technique to learn Animal welfare The patient s wellbeing, great PR with your clients and your staff Lowers patient mortality and morbidity No client objection to cost of analgesia
contraindications hypovolaemia fixed cardiac output sepsis/local skin infection coagulation disorders
ligamentum flavum spinal cord cauda equina CSF epidural space
Location of the lumbosacral space Most dorsally prominent points of the wings of the ilium
L7 S1
Lumbosacral space
epidural analgesia you will need: morphine (10 mg per ml, preservative free) bupivicaine 0.5% 22g spinal needles (1.5 & 3 inches) 2, 5 or 10 ml glass syringe (or plastic loss of resistance syringe) sterile paper drape syringes, gloves etc
sterile, single use, plastic loss of resistance syringe
epidural analgesia dose rates 0.5% bupivicaine 0.2 ml/kg morphine (10 mg/ml) 0.1 mg/kg The drugs are mixed in the one syringe prior to injection.
Open all of the sterile items
morphine 10mg/ml
morphine 10mg/ml
bupivicaine 0.5%
Add the morphine to the bupivicaine and mix
epidural analgesia position» ventral or» lateral iv fluids» 10-20 ml/kg bolus
Prepare as for aseptic surgery» iodine scrub» chlorhexidine/ alcohol» iodine solution epidural analgesia
epidural analgesia palpate dorsal prominence of wings of the ilium palpate lumbosacral space
epidural analgesia 22 g spinal needle insert at the lumbosacral space advance until just through ligamentum flavum
epidural analgesia remove stylet observe for CSF
epidural analgesia remove stylet observe for CSF If CSF, discard 2/3 of solution and top up morphine to 0.1 mg/kg
Injection of local anaesthetic into the CSF is often termed spinal anaesthesia. Compared to epidural anaesthesia, a smaller volume is used to avoid excessive cranial spread of the solution. Onset of analgesia is more rapid with spinal anaesthesia than with epidural anaesthesia. If CSF appears in the hub of the needle or can be aspirated then the loss of resistance test is not needed
epidural analgesia remove stylet observe for CSF observe for blood if blood is seen, withdraw needle, clean & try again
epidural analgesia loss of resistance test glass syringe or plastic Loss of resistance syringe tight fit on needle air or saline
Loss of resistance Disposable syringe
epidural analgesia inject drugs over 30-60 seconds onset of action: bupivicaine 20 min lignocaine 10 min morphine 40 min
epidural analgesia The epidural local anaesthetic results in a blockade of the somatic nervous system and sympathetic nervous system Total peripheral resistance falls about 30% Administer IV fluids bolus prior to surgery 10-20ml/kg replacement fluids over 10 minutes
epidural analgesia Position in dorsal or lateral recumbency for 5-10 minutes to bathe sensory (dorsal) spinal nerve roots. :
epidural analgesia Position in dorsal or lateral recumbency for 5-10 minutes to bathe sensory (dorsal) spinal nerve roots. : With lateral recumbency, the patient should be positioned so that the the surgical site is dependent.
epidural analgesia Next... reduce concentration of volatile anaesthetic maintain light level of general anaesthesia monitor arterial pressure
epidural analgesia during recovery from anaesthesia: give NSAID empty bladder re-warm duration of analgesia: epidural morphine = 12-24 hours epidural bupivicaine = 4-6 hours
epidural analgesia during recovery from anaesthesia: With» give bupivicaine, NSAID the sensory block lasts longer than the motor block.» empty Very occasionally, bladder some block will persist for more than» re-warm 12 hours after the injection. duration of analgesia: epidural morphine = 12-24 hours epidural bupivicaine = 4-6 hours
potential problems neurological damage vanishingly rare infection extremely rare (1 in 5,000) provided aseptic technique hypotension common, but easily managed with IV fluid load Hypotension with local anaesthetics (TPR 30%) Segmental sympathetic blockade T12 greater splanchnic nerve Cardio-acceleratory sympathetic nerves RHS T1-4 Supraspinal effects especially hydrophilic morphine absorption into CSF systemic absorption
potential problems Constipation occasional urinary retention common, easily managed by expressing or catheterising bladder after surgery pruritis unusual inadvertent subarachnoid (spinal) injection especially cats and young dogs inadvertent IV injection causing cardiac arrest rare, treat CPR + IV 20% Intralipid 1.5ml/kg
Artificial ventilation
Artificial ventilation For full presentation on artificial ventilation please go to www.stah.net.au and select the tab labelled For Veterinarians
Artificial ventilation A practical guide
adverse effects of IPPV circulation reduction of blood flow to right atrium increase in pulmonary input impedance reduced capacitance of pulmonary bed
adverse effects of IPPV Try not to exceed a maximum inspiratory pressure of 20cm H 2 O Unless the airway pressure is measured with a manometer, you don t know!
adverse effects of IPPV circulatory effects minimised by: increase in tone of capacitance vessels minimise depression of the sympathetic nervous system adequate circulating volume minimise mean airway pressure Inspiratory to expiratory time ratio I:E ratio < 1:2 abolition of thoracic& abdominal m. tone maximise inspiratory flow rate fast & slow alveoli
adverse effects of IPPV barotrauma High inspiratory pressures can lead to pneumothorax or pneumomediastinum closed chest: damage with inflation pressures > 70 cm H 2 O open chest: damage with inflation pressures > 40 cm H 2 O
adverse effects of IPPV Barotrauma or volutrauma? Hyperinflation (volutrauma) injures the diseased lung Overdistension is more insidious and ultimately more injurious than barotrauma Hyperinflation leads to gross oedema, increased lung weight and cellular damage
adverse effects of IPPV Barotrauma or volutrauma? Total lung volume is reduced in pulmonary disease associated with trauma or sepsis Ventilation with a normal tidal volume may approach total lung capacity Damage is diffuse & heterogenous in the diseased lung.(slow and fast alveoli)
adverse effects of IPPV Volutrauma and the diseased lung Extensive research on ARDS and animal models of acute lung injury Lung injured animals subject to high airway pressures & normal tidal volumes gross pathology changes similar to paired control high tidal volumes led to gross oedema, increased lung weight & cellular damage Damage due to overdistension is synergistic with toxininduced pulmonary endothelial injury
adverse effects of IPPV In Summary: There is a considerable differences in the ventilatory requirements of a patient with healthy lungs compared to that with lung damage or disease. Provision of artificial ventilatory must match individual patient needs in order to optimise outcomes.
Measure peak inspiratory pressure circle absorber Bain
Choices of ventilator 1. Direct patient ventilator 2. Anaesthetic machine ventilator 3. Using a direct patient ventilator to run as an anaesthetic machine ventilator o Bag in the bottle (2 separate circuits) o Connect ventilator by a long 22mm corrugated tubing to the connection site of the rebreathing bag in the anaesthetic machine s patient breathing circuit (circle, Bain or T piece)
Direct patient ventilator
Anaesthetic machine ventilator
Using direct patient ventilator as an anaesthetic machine ventilator
Artificial ventilation: Monitor!
Cardiopulmonary rescucitation
Latest on CPR Journal of Veterinary Emergency and Critical Care 22(2) 2012, pp 148 159 Updates in the American Heart Association guidelines for cardiopulmonary resuscitation and potential applications to veterinary patients Barbara L. Maton, DVM and Sean D. Smarick, VMD
Latest on CPR: technique Be selective. Acute arrest: Yes Chronic underlying disease: result of many slowly developing derangement until cumulative effect is catastrophic: No ABCDEF for pets CABDEF for people Airway, breathing, circulation drugs, electrical defibrillation, follow up
Latest on CPR: technique Dog < 15kg cardiac pump 3 rd -6 th rib lower third chest 100-130 beats/min Dog > 15kg thoracic pump 7 th -8 th rib at widest chest 100 beats/min
Latest on CPR: ABC or CAB ABC in pets as most arrests are PEA, asystole and associated with respiratory disease and hypoxia Right lateral recumbency, preferably head down Continuous chest compressions 100-120/min. Do not stop (at most 10 sec interruptions) IPPV but don t stop chest compressions Between breaths allow lungs to fully deflate (to FRC) Dog < 15kg cardiac pump 3 rd -6 th rib lower third chest Dog > 15kg thoracic pump 7 th -8 th rib at widest chest Internal cardiac massage after 2-5min esp. big dogs
Latest on CPR: Defibrillation o Electrical defibrillation o External o 2 5 Joules/kg (up to 10) monophasic. o Biphasic defibrillators 30% (higher survival) o Internal 0.1-0.5 Joules kg -1 o Lowest energy setting, then step dose up after each unsuccessfully shock o Cardiac massage inter discharge for 2 minutes
Latest on CPR: drugs Adrenalin 0.1mg/kg (0.1ml/kg 1:1000) iv Then maintenance 0.1ug/kg/min (1ml 1:1000 to 1L Hartmann s soln, infuse at 1ml/10kg/min) Vasopressin Vasoconstrictor 0.8 u/kg iv. Can repeat once Asystole, VF, VT & PEA (pulseless electrical activity), EMD Electromechanical dissociation, Non-perfusing rhythm Superior to adrenalin for VT in animals
Latest on CPR: drugs Anti-arrythmics Lidnocaine 1-4mg/kg. VT or relapsing VF after CPR Amiodarone 5mg/kg IV over 10 mins. Shock resistant VT & VF, AF, narrow complex SVT. Do not use: Ca, glucose, atropine, HCO3
Latest on CPR: drugs Administration of drugs IV, followed by saline chaser, elevate arm 10-20 sec IV is best IO (Intra-osseous administration) is good, IT (intra-tracheal) is last resort. Double dose except adrenalin 10x dose and dilute in 5-10ml sterile water. IC (intra-cardiac) not recommended
Latest on CPR: drugs IV Fluids Only shock doses if pre-arrest hypovolemia Euvolemia: Crystalloids D 20ml/kg bolus C 10ml/kg bolus Hetastarch D 5ml/kg bolus C 2.5ml/kg bolus 7.5% saline D 2-4ml/kg Hypothermia. 33-34oC is OK post-arrest Success =Team work. Requires leaning and practice
Practise
CPR Protocol latest recommendations For free copies www.stah.net.au