Anaesthetics Flashcards
How to evaluate a difficult airway?
LEMON Look Evaluate (3-3-2) Mallampati score Obstruction Neck mobility
How to assess for ventilation difficulty?
BONES Beard Obesity No teeth Elderly Snoring hx
What is the 3-3-2 rule?
3 fingers should fit in mouth
3 fingers from mandible to hyoid (hyoid-mental distance)
2 fingers in superior laryngeal notch (thyroid mouth distance)
What are the Mallampati scores?
1 = full view of uvula 2 = body + base of uvula 3 = base of uvula 4 = only hard palate + tongue, no other structures visible
What are the indications for CBC pre-op?
Major surgery needing group + screen or X match
Chronic CV, pulmonary, renal or hepatic disease
Malignancy
Anaemia
Bleeding diathesis
Myelosuppression
Pt <1 y/o
What are the indications for sickle cell screen pre-op?
Genetically predisposed pt
What are the indications for INR + aPTT pre-op?
Anticoagulant therapy
Bleeding diathesis
Liver disease
What are the indications for electrolytes + creatinine pre-op?
HTN Renal disease DM Pituitary or adrenal disease Vascular disease Digoxin Diuretics
What are the indications for fasting glucose pre-op?
DM
What are the indications for ECG pre-op?
Heart disease DM SAH/ ICH CVA Head trauma
What are the indications for chest xray pre-op?
New or worsening resp symptoms
What are the ASA grades?
1 = healthy, fit 2 = mild systemic disease eg controlled HTN 3 = severe systemic disease eg COPD 4 = incapacitating disease, constant threat to life eg acute resp failure 5 = moribund pt not expected to survive eg ruptured AAA 6 = brain dead
What medications should be stopped pre-op + in what timeframes?
Oral antihyperglycaemics - avoid on morning of surgery
ACEi + ARBs = avoid on day of surgery
Warfarin (bridge with heparin), aspirin, clopidogrel etc
Stop herbs 1 week before
What medications should be adjusted pre-op?
Insulin, prednisone, bronchodilators
What is the BP target pre-op?
<180/110
What considerations should be taken pre-op with someone with CAD?
Min 60 days after MI before non-cardiac surgery in absence of coronary intervention
If operation has to occur, invasive ICU monitoring is required
Consider giving BB peri-op (particularly for high risk surgery eg vascular surgery)
What advice should be given re smoking pre op?
Abstain for 8 weeks pre-op
If unable, 24hrs increases O2 availability
What are non-selective BB?
Labetalol, nadolol = block both B1 + B2
What considerations are involved with asthma?
Increased risk of bronchospasm with intubation Short course (1 week) of pre-op corticosteroids + inhaled B2 agonists decreases risk Use cardio-selective BB such as metoprolol + atenolol Delay surgery by 6 weeks if URTI develops
What increases risk of aspiration?
Decreased LOC Delayed gastric emptying (narcotics, DM, non fasted for 8 hrs) Decreased sphincter competence Increased abdo pressure Unprotected airway
Fasting guidelines
8hrs = meal including meat, fried or fatty food 6hrs = light meal eg toast or infant formula 4hrs = breast milk 2hrs = clear fluids
Considerations for pts with haematological disorders
Pre-op treatment to increase Hb (iron, erythropoietin)
Modify anti-coagulants
Administer reversal agents if needed
Considerations for pts with DM
Target blood glucose <10 in critical pts, <7.8 in stable pts
Use insulin therapy
Hold oral hypoglycaemics
Consider cancelling surgery if metabolic abnormality present eg DKA, HHS or if glucoe over 22.2-27.7
Considerations for pts with hyperthyroidism
Can cause sudden release of thyroid hormone (thyroid storm) so treat with BB and pre-op prophylaxis
What is the pre-anaesthetic checklist?
SAMMM
Suction - connected + working
Airways - all equipment present
Machine - connected, pressures ok, vaporizers full
Monitors - connected + working
Medications - IV fluids ready, emergency meds ready
What are the guidelines to the practice of anesthesia + patient monitoring?
An anesthetist present
Completed pre-anesthetic checklist - ASA class, NPO policy, Hx + Ix
Peri-op record: HR + BP every 5 mins, O2 sats, end tidal CO2, dose + route of drugs + fluids
What routine monitoring is required for all cases?
Pulse oximeter, BP, electrocardiography, capnography (for GA + sedation 4-6), agent specific gas monitor
What other monitoring should be available?
Temp probe, nerve stimulator, stethoscope, lighting, spirometry, manometer to measure ETT cuff pressure
How is anaesthetic depth monitored?
End tidal inhaled anesthetic monitoring, EEG monitoring (Bispectral index monitor)
What findings suggest inadequate depth of anaesthesia?
Blink reflex present, HTN, tachycardia, tearing or sweating
What elements need monitoring?
Anesthetic depth Oxygenation Ventilation Circulation Temperature Urine output
Describe the anatomy of the airway - the borders of the pharyngeal airway, what the glottic opening is + where the trachea begins + bifurcates
Pharyngeal airway extends from posterior aspect of nose to cricoid cartilage
Glottic opening is narrowest segment of laryngeal opening
Trachea begins at level of thyroid cartilage, C6, and bifurcates at T4-5 (approx sternal angle)
What are the definitive + non-definitive methods of supporting the airway?
Definitive = ETT, surgical airway Non = jaw thrust, oro + nasopharyngeal airway, bag mask ventilation, LMA
What equipment is needed for intubation?
Monitors Drugs Suction O2 source + oro/ naso airways Laryngoscope ETT Stylet + syringe for tube cuff inflation
What meds can be given through the ETT?
NAVEL Naloxone Atropine Ventolin Epinephrine Lidocaine
What are the indications for an ETT?
Pt airway Protects against aspiration Positive pressure ventilation Pulmonary toilet (suction) Pharmacological administration
What is the sizing for LMA?
40-50kg = 3 50-70kg = 4 70-100kg = 5
What is the sizing for ETT?
Male = 8-9mm
Female = 7-8mm
Paed uncuffed >2 = age/ 4 + 4mm
What is the proper positioning for intubation?
Align 3 axis (mouth, pharynx + larynx)
Sniffing position = flexion of C5/6, bow head forward, extension of C spine at atlanto-occipital joint (C1)
Where is the laryngoscope tip placed?
In epiglottic vallecula
What is the DDx for poor bilateral breath sounds after intubation?
DOPE Displaced ETT Obstruction Pneumothorax Esophageal intubation
What is the foreign body reflex in the trachea?
Sympathetic response due to stimulation of CN9 + 10
Causes tachycardia, dysrhythmias, myocardial ischaemia + increased BP
Risks of ETT too deep or too shallow
Too deep = right sided tension pneumothorax, left sided atelectasis
Too shallow = extubation, vocal cord trauma, laryngeal palsy
Where should the tip of the ETT be?
Midpoint of trachea, 2cm above carina
Proximal end of cuff at least 2cm below vocal cords
What cm mark should be at the corner of the mouth for the ETT?
Men - 20-23cm
Women = 19-21cm
How to confirm ETT placement?
Direct = visualising ETT pass through cords, visualising ETT in trachea Indirect = ETCO2, auscultate breath sounds, bilateral chest movement, condensation, no abdo distension, refilling of reservoir bag
What is the Cormack-Lehane classification of laryngeal view?
1 = all laryngeal structures revealed 2 = posterior laryngeal 2A (posterior vocal cords) 2B (arytenoids) 3 = larynx concealed, only epiglottis 4 = neither glottis nor epiglottis
What to do if intubation unsuccessful after induction?
Call for help
Ventilate with bag mask
Consider returning to spontaneous ventilation/ waking pt
What is the goal of O2 therapy?
O2 sats >90%
When is cyanosis detected (+ frank cyanosis)?
SaO2 <85%
Frank cyanosis at <67&
What are low flow systems?
0-10L/min
Acceptable if tidal vol 300-700ml, RR <25, consistent ventilation pattern
eg nasal cannula
What FiO2 is supplied with a nasal cannula?
At 1-6L/min = 24-44%
What are reservoir systems?
Reservoir accumulates O2 eg face mask or non-rebreathe mask
What FiO2 is supplied with a face mask + non-rebreathe mask?
Face mask = 55% at 10L
Non-rebreathe = 80% at 10-15L
What are high flow systems?
Flow up to 50-60L
E.g. venturi mask ranging from 24-50%
What are the indications for mechanical ventilation?
Apnea
Hypoventilation
Acute resp acidosis
Intraoperative positioning
To deliver positive end expiratory pressure (PEEP)
If there is increased intrathoracic pressure
What are the airway complications of mechanical ventilation?
Tracheal stenosis, laryngeal oedema
Ventilator induced lung injury (barotrauma)
Nosocomial pneumonia
What are the cardiac complications of mechanical ventilation?
Reduced venous return
Reduced cardiac output
Hypotension
What are the neuromuscular complications of mechanical ventilation?
Muscle atrophy
Increased ICP
What are the metabolic complications of mechanical ventilation?
Hyperventilation = decreased CO2
Alkalemia
How do you monitor ventilator therapy?
Pulse oximetry, end tidal CO2
Regular ABGs
Pts who develop a pneumothorax while being ventilated need what?
Chest tube
How can ventilation help with hypoxaemic resp failure?
Helps improve V/Q match
Provides O2
Recruits atelectatic lung segments
Decreases interpulmonary shunt
How can ventilation help with hypercapnic resp failure?
Augments alveolar ventilation
Decreases work of breathing
Allows resp muscles to rest
What is assist-control or volume control ventilation?
Every breath has pre-set tidal volume + rate or minute ventilation
Ventilator initiates breath if no pt effort
What is pressure control ventilation?
Minimum frequency set, pt may trigger breaths above ventilator
All breaths delivered at preset constant inspiratory pressure
Changes in compliance + resistance affect tidal volume
What is synchronous intermittent mandatory ventilation?
Ventilator provides controlled breaths (either with VC or PCV)
Pts can breathe spontaneously between controlled breaths
What is pressure supported ventilation?
Pt initiates all breaths + ventilator supports each breath with pressure
Useful for weaning off ventilator
What is high frequency oscillatory ventilation?
High breathing rate, very low tidal volumes
Used in neonatal/ paeds resp failure
What is non-invasive positive pressure ventilation?
BiPAP + CPAP
Causes of decreased end tidal CO2?
Hyperventilation Hypothermia Decreased pulmonary blood flow V/Q mismatch PE Pulmonary edema Air embolism
Causes of increased end tidal CO2?
Hypoventilation
Hyperthermia
Improved pulmonary blood flow eg after resuscitation or hypotension
Low bicarbonate
Causes of hypothermia intra-op
Environment
Open wound
What is the impact of hypothermia (<36)?
Increased risk of wound infections due to impaired immune function
Increased period of hospitalisation
Reduced platelet function increasing blood loss
Triples incidence of VT
Decreases metabolism of anaesthetics prolonging recovery
Causes of hyperthermia intra op
>37.5 Drugs - atropine Blood transfusion reaction Infection Thyrotoxicosis Malignant hyperthermia Over-zealous warming efforts
Which cardiac arrests are shockable vs not?
Shockable = VT + VF Not = PEA + asystole
What are the reversible causes of cardiac arrest?
5Hs + 5Ts Hypothermia Hypovolaemia Hypoxia Hydrogen ions (acidosis) Hypo/hyperkalaemia Tamponade Tension pneumothorax Toxins Thrombosis (pulmonary or cardiac)
What are the SVTs?
Narrow complex Sinus tachycardia AF/ flutter Accessory pathway mediated Paroxysmal atrial tachycardia
What are the wide complex tachycardias?
VT, SVT with aberrant conduction
What are causes of sinus tachycardia?
Shock/ hypovolaemia/ blood loss
Anxiety/ pain/ light anaesthesia
Full bladder
Anaemia
Febrile illness/ sepsis
Drugs - atropine, cocaine, dopamine, epinephrine, ephredrine, isoflurane, isoproterenol, pancuronium
Addisonian crisis, hypoglycaemia, malignant hyperthermia + transfusion reaction
What is the boundary for tachy + bradycardia?
Tachy >150
Brady <50
What are the causes of sinus bradycardia?
Increased parasympathetic tone vs decreased sympathetic tone
Hypoxemia
Arhythmias
Baroreceptor reflex due to increased ICP or BP
Vagal reflex
Drugs - opioids, edrophonium, neostigmine, halothane, digoxin, BB
High spinal anaesthesia
What are the causes of intra-op shock?
SHOCA Sepsis or spinal Hypovolaemia/ haemorrhagic Obstructive Cardiogenic Anaphylactic
What are the causes of intra-op HTN?
Inadequate anaesthesia causing pain Pre-existing HTN Hypoxemia Hypervolemia Increased ICP Full bladder Drugs - ephedrine, epinephrine, cocaine, phenylephrine, ketamine Allergic reaction Malignant hyperthermia NMS/ serotonin syndrome
What is the total requirement for fluids?
Total = maintenance + deficit + ongoing loss
What is the average total requirement due to what losses?
2500 =
200 GI loss
800 insensible losses (resp, sweat)
1500ml urine
What should the maintenance rate not exceed?
No more than 3ml/kg/hr
When are there increased requirements for fluids?
Fever Sweating GI losses Adrenal insufficiency Hyperventilation Polyuric renal disease
When are there decreased fluid requirements?
Anuria
SIADH
Highly humidified atmospheres
CHF
What are the maintenance electrolyte requirements?
Na+ = 3 mEq/kg/d K+ = 1 mEq/kg/d
How much is the total body water?
60% of male body weight
50% of female body weight
What does the total Na content + [Na+] determine?
Content = ECF volume Conc = ICF volume
What causes Na+ loss?
GI losses Insensible losses Haemorrhage Renal loss Diuretics Osmotic diuresis Hypoaldosteronism Salt wasting nephropathies Diabetes insipidus Decreased CO Hypoalbuminaemia (cirrhosis, nephrotic syndrome) Capillary leakage (pancreatitis, rhabdomyolysis, ischemic bowel, sepsis)
How should chronic hyponatraemia be corrected?
Slowly over 48hrs to avoid central pontine myelinosis
What % body water loss classifies mild, mod + severe dehydration, and what are the S+S?
3% = decreased skin turgor, sunken eyes, dry mucus membranes, dry tongue, reduced sweating 6% = oliguria, hypotension, tachycardia, cool extremities, reduced filling of veins, haemoconcentration, apathy 9% = profound oliguria, compromised CNS function +/- altered sensation
What are crystalloid fluids - which ones are used + what is the fluid: blood loss ratio?
Salt-containing solutions distributed in ECF only
Use Ringer’s lactate for routine replacement + large infusions as saline can cause hyperchloraemic acidosis
3ml infusion for 1ml of blood loss
What are colloid fluids - which ones are used + what is the fluid: blood loss ratio?
Includes protein colloids (albumin + gelatin) + non-protein (dextrans + starches)
Distributes in intravascular volume
1:1
What is the blood volume of infants, males + females?
Blood volume:
Infant = 80ml/kg
Female = 60ml/kg
Male = 70ml/kg
What are the transfusion infection risks for HIV, Hep C + B, HTLV, bacterial sepsis, West Nile virus?
HIV = 1 in 21 million Hep C = 1 in 13 million Hep B = 1 in 7.5 million HTLV = 1 in 1-1.3 million Bacterial sepsis = 1 in 40,000 from platelets + 1 in 250,000 from RBC West Nile virus = No cases since 2003
Describe the process of routine induction
Equipment prep 100% O2 for 3 mins or 4-8 vital capacity breaths Use induction agent Use muscle relaxant Bag mask ventilation Posterior pressure on thyroid cartilage Intubate, inflate cuff, confirm ETT position Secure ETT + begin ventilation
Describe the process of RSI
Equipment prep
100% O2 for 3 mins or 4-8 vital capacity breaths
Use fast-acting induction agent - pre-determined dose
Use muscle relaxant (Sch or Roc) immediately after
Selick maneuver (cricoid pressure)
Intubate once paralysed, inflate cuff, confirm ETT position
Secure ETT + begin ventilation
Which volatile anaesthetics are most soluble to least soluble?
Halothane > Isoflurane > Sevoflurane > Desflurane > NO2
What is the class, action, indication, cautions, dosing + special considerations for propofol?
Class = alkylphenol - hypnotic
Action = inhibitory at GABA synapse, decreased cerebral metabolic rate, decreased ICP, SVR, BP + SV
Indication = induction, maintenance, TIVA
Cautions = pts who can’t tolerate sudden BP drop (eg fixed cardiac output/ shock)
Dosing = 2.5-3mg/kg
Special considerations = reduce burning at IV site by giving with lidocaine.
Decreased post-op sedation, less N+V
What is the class, action, indication, cautions, dosing + special considerations for thiopental?
Class = short-acting barbiturate - hypnotic
Action = inhibitory at GABA synapse. Decreased CPP, CO, BP, respiration + reflex tachycardia
Indication = induction, anticonvulsants, obstetrics
Cautions = uncontrolled hypotension, shock, cardiac failure
Dosing = 3-5mg/kg
Special considerations = long lasting post-op sedation
Accumulates with repeat dosing
What is the class, action, indication, cautions, dosing + special considerations for ketamine?
Class = phenylcyclidine derivative
Action = NMDA antagonist, increased HR, BP, SVR, resp depression, smooth muscle relaxation
Indication = trauma, hypovolaemia, asthma
Cautions = TCA meds interact causing HTN, also caution in psychotic pts
Dosing = 1-2mg/kg
Special considerations = emergence reactions.
Pretreat with glycopyrrolate to decrease salivation
What is the class, action, indication + cautions for benzos?
Class = Anxiolytic Action = Inhibitory at GABA. Minimal cardiac depression Indication = sedation, amnesia, anxiolysis Cautions = marked respiratory depression
What is the class, action, indication, cautions, dosing + special considerations for etomidate?
Class = imadazole derivative - hypnotic
Action = decreases conc of GABA required to activate receptor. CNS depression
Indication = induction, poor cardiac function, uncontrolled HTN
Cautions = PONV, venous irritation
Dosing = 0.3mg/kg
Special considerations = causes adrenal suppression, causes myoclonic movements during induction
What is the MAC + effect on CNS, resp + cardiac system of sevoflurane?
MAC = 2 CNS = increased ICP Resp = decreased TV, increased RR, bronchodilation CVS = less decrease of contractility, stable HR
What is the MAC + effect on CNS, resp + cardiac system of desflurane?
MAC = 6 CNS = Increased ICP Resp = decreased TV, increased RR, bronchodilation CVS = tachycardia w/ increase in concentration
What is the MAC + effect on CNS, resp + cardiac system of isoflurane?
MAC = 1.2 CNS = decreased cerebral metabolic rate, increased ICP Resp = decreased TV, increased RR, bronchodilation CVS = decreased BP + CO, increased HR
What is the MAC + effect on CNS, resp + cardiac system of enflurane?
MAC = 1.7 CNS = ECG seizure like activity, increased ICP Resp = decreased TV, increased RR, bronchodilation CVS = stable HR, decreased contractility
What is the MAC + effect on CNS, resp + cardiac system of halothane?
MAC = 0.8 CNS = increased ICP + cerebral blood flow Resp = decreased TV, increased RR, bronchodilation CVS = decreased BP, CO, HR + conduction
What is the MAC + effect cardiac system of N20?
MAC = 104 CVS = decrease HR in paeds pts with existing heart disease
What is MAC?
Minimum alveolar conc needed to prevent movement in 50% of pts in response to surgical stimulus
What factors increase MAC?
Chronic alcohol use, hyperthyroidism, hyperthermia, stimulants, young age
What factors decrease MAC?
Acute alcohol intoxication, hypothermia, sedating drugs, advanced age, drugs (opioids + benzos)
How does MAC change for every decade of life?
Decreases by 6%
What is MAC-intubation?
1.3
What is MAC-block adrenergic response?
1.5
What is MAC-awake?
0.3-0.4
What is the action, intubating dose, onset, duration, metabolism, indications + SE of succinylcholine (SCh)?
Action - mimics Ach causing prolonged depolarisation, initial fasciculations seen then paralysis secondary to block ACh receptors
Intubating dose = 1-1.5
Onset = 30-60s
Duration = 3-5 mins
Metabolism = hydrolysed by plasma cholinesterase
Indications = intubation, increased risk of aspiration, short procedures, ECT, laryngospasm
SE = low HR, increased salivation, hyperkalaemia, trigger malignant hyperthermia, increased ICP/ IOP, fasciculations
Contraindications to SCh?
MH, myotonia, high risk for hyperkalaemia
Relative: myasthenia gravis, open eye injury
What is the intubating dose, onset, duration + metabolism of mivacuronium?
Intubating dose = 0.2
Onset = 2-3 mins
Duration = 15-25 mins
Metabolism = cholinesterase
What is the mode of action of non-depolarising muscle relaxants?
Competitive blockage of postsynaptic ACh receptors preventing depolarisation
What is the order or non-depolarising muscle relaxants, from short to long acting?
Short = Mivacuronium - Rocuronium Int = Vecuronium - Cisatracurium Long = Pancuronium
What is the intubating dose, onset, duration + metabolism of rocuronium?
Intubating dose = 0.6-1
Onset = 1.5 mins
Duration = 30-45 mins
Metabolism = Liver (major) + renal (minor)
What is the intubating dose, onset, duration + metabolism of vecuronium?
Intubating dose = 0.1
Onset = 2-3 mins
Duration = 45-60 mins
Metabolism = Liver
What is the intubating dose, onset, duration + metabolism of cisatracurium?
Intubating dose = 0.2
Onset = 3 mins
Duration = 40-60 mins
Metabolism = Hofmann eliminations
What is the intubating dose, onset, duration + metabolism of pancuronium?
Intubating dose = 0.1
Onset = 3-5 mins
Duration = 90-120 mins
Metabolism = renal (major) + liver (minor)
Which non-depolarising muscle relaxants release histamine?
Mivacuronium
How are reversal agents used?
Administered when there is some recovery of blockade (muscle twitch)
Reverse effects of non-depolarising
Anticholinergic agents (atropine, glycopyrrolate) are given simultaneously to minimised muscarinic effect of reversal agents
What is the action of reversal agents?
Sugammadex = selective relaxant bnding agent
Neostigmine, edrophonium = ACh inhibitors
Dose, recommended anticholinergic + onset of pyridostigmine?
Slow onset
0.1-0.4 mg/kg
Give with glycopyrrolate 0.05mg
Dose, recommended anticholinergic + onset of neostigmine?
Intermediate onset
0.04-0.08 mg/kg
Give with glycopyrrolate 0.2 mg
Dose, recommended anticholinergic + onset of edrophonium?
Intermediate onset
0.5-1 mg/kg
Give with atropine 0.014mg
What is the dose + action of sugammadex?
Action - encapsulates roco + vecu + decreases amount of agent available at NMJ
2-16 mg/kg
What are the complications of early extubation?
Aspiration
Laryngospasm
What are the complications of late extubation?
transient vocal cord incompetence, oedema, pharyngitis, tracheitis
How to treat laryngospasm?
Sustained pressure with bag mask valve at 100%
Low dose propofol (0.5-1 mg/kg)
Low dose succinylcholine (0.25 mg/kg)
What is regional anaesthesia?
LA applied around peripheral nerve
No CNS depression
What landmarks indicate L4 + T7?
L4 = between iliac crests T7 = tip of scapula
What is the classic presentation of a dural puncture headache?
Onset 6h - 3d after puncture
Postural component
Occipital or frontal localisation
+/- tinnitus, diplopia
What structures are penetrated outside to inside for a spinal/ epidural?
Skin SC fat Supraspinous ligament Interspinous ligament Ligamentum flavum EPIDURAL Dura Arachnoid SPINAL
What are the differences between spinal + epidural?
Epidural has a slower onset (15 mins)
Effectiveness can be variable with epidural
Spinal uses smaller dose of LA
Epidural can give continuous infusion due to catheter
Mode of action of LA
Bind to receptors on cytosolic side of Na+ channel, inhibiting Na+ flux + blocking impulse conduction
How is LA metabolised?
Esters = broken down by plasma + hepatic esterases, excreted by kidneys Amides = broken down by hepatic oxidases (P450) + excreted by kidneys
What are the types of LA?
Ester = procaine, tetracaine Amide = lidocaine, bupivacaine
What factors affect choice of LA?
Onset of action (lower pKa = higher conc of LA = faster onset)
Duration of effects (influenced by protein binding)
Potency (influenced by lipid solubility)
Potential for toxicity
What is the order of duration, from short to long, of LA?
Short: chloroprocaine (15-30 mins)
Lidocaine
Bupivacaine
Ropivacaine (2-8hrs)
What are the effects in order of appearance of LA toxicity?
Numbness of tongue, metallic taste, tingling Disorientation, drowsiness Tinnitus Visual disturbances Muscle twitching Unconsciousness Convulsions CNS depression
What are the effects on the CVS of LA toxicity?
Vasodilation
Hypotension
Decreased contractility
Bradycardia
What is the treatment for LA toxicity?
Get help 100% O2, manage ABCs Diazepam to prevent seizures Manage arrhythmias Intralipid 20%
Where not to use LA with epinephrine?
Ears Fingers Toes Penis Nose
How to treat PONV?
Dimenhydrinate (Gravol) Metoclopramide (Maxeran) - not with bowel obstruction Prochlorperazine (Stemetil) Ondansetron (Zofran) Granisetron (Kytril)
What are RF for PONV?
Young age
Female
Hx of PONV
Non-smoker
Type of surgery = ophtho, ENT, abdo/ pelvic, plastics
Type of anaesthetics = N2O, opioids, volatile agents
How can post-op HTN be treated?
IV nitroglycerin, hydralazine, CCB ot BB
What is the definition of pain + nociception?
Pain = perception of nociception, occurs in brain Nociception = detection, transduction, transmission of noxious stimuli
How is pain classified?
Temporal eg acute vs chronic
Mechanism eg nociceptive vs neuropathic
When should NSAIDs be used with caution?
Asthma Coagulopathy GI ulcers Renal insufficiency Pregnancy, 3rd trimester
What are the common SE of opioids?
N/V Constipation Sedation Pruritus Abdo pain Urinary retention Resp depression
What to consider prescribing alongside opioids?
Breakthrough dose
Anti-emetics
Laxative
What are the PCA parameters?
Loading dose Bolus dose Lockout interval Continuous infusion Maximum 4h dose
What are the nociceptive pathways in labour + delivery?
Labour = cervical dilation + effacement stimulates visceral nerve fibres at T10-L1 Delivery = distension of vagina causes somatic impulses via pudendal nerve at S2-S4
What are the anaesthetics considerations in pregnancy?
Increased blood volume + increased RBC mass Decreased SVR = decreased BP Decreased MAC Delayed gastric emptying Increased abdo pressure Increased risk of aspiration
What are the options for analgesia during labour?
Psychoprophylaxis = Lamaze method (breathing)
Systemic meds = risk of resp depression (opioids if delivery not expected within 4hrs)
Inhalational analgesia = 50% nitrous oxide
Neuraxial = hypotension most common SE, epidural given as it keeps motor function intact
What respiratory differences are there for paeds?
Anatomical differences = large head, short trachea, large tongue, adenoids + tonsils Narrow nasal passages Epiglottis is longer, U shaped Faster RR Less oxygen reserve Greater V/Q mismatch Greater work of breathing
What CVS differences are there for paeds?
High HR + low BP
CO is dependant on HR
What other differences are there for paeds?
Vulnerable to hypothermia
MAC of halothane increased
NMJ is immature - increased sensitivity to muscle relaxants
Vulnerable to hypoglycaemia
Higher dose requirements because of higher TBW
Greater permeability of BBB - opioids more potent
What is malignant hyperthermia?
Hypermetabolic disorder of skeletal muscle
Uncontrolled increase in intracellular Ca+
Autosomal dominant
Triggered by inhalational agents + SCh
What are the signs of MH?
Increased O2 consumption Rise in ETCO2 Increase in minute ventilation Tachycardia HTN Rigidity Hyperthermia
What are the muscular symptoms of MH?
Trismus (masseter spasm)
Rhabdomyolysis
Rigidity
Complications of MH
Coma DIC Rhabdomyolysis Hyperkalaemia ARDS
Management of MH
Some Hot Dude Better Get Iced Fluids Fast
Stop triggering agents Hyperventilate Dantrolene 2.5mg/kg every 5 mins Bicarbonate Glucose + insulin IV fluids, cool pt to 38 Fluid output, consider furosemide Tachycardia - prepare to treat VT
What is abnormal pseudocholinesterase?
Hydrolyzes SCh + mivacurium
Abnormal = prolonged muscular blockage
When are naso + oropharyngeal airways useful?
Naso - better tolerated but not to be used in ?basal skull fracture
What is the most common cause of obstruction when a pt is under GA?
Tongue
How do you measure endotracheal tube size?
Internal diameter in mm
What is the best indicator that the endotracheal tube is in place?
Expired CO2
What is the WHO checklist for surgery?
Checklist for surgery safety
Before induction of anaesthesia
Before skin incision
Before patient leaves operating room
How to measure oro + nasopharyngeal airways?
Oro = incisors to angle of jaw Naso = tip of nose to tragus of ear
What are supraglottic airways?
Sit abutting the larynx above vocal cords
Not definitive due to risk of aspiration
Good for short/ low risk procedures
What is a laryngeal mask airway?
Reusable supraglottic device
What is an iGel?
Single use supraglottic device
What is Yankaur suction used for?
To clear oropharynx
Describe endotracheal tubes + sizing
7 in women, 8 in men
Small hole in end called Murphy’s eye = used for ventilation if end is obstructed
Tube should sit at 20-24cm at the teeth
What is a bougie used for?
Can be moulded + used for difficult airways
What are neuromuscular blockers + the 2 types?
Muscle relaxants used in GA
Non-depolarising (compete with acetylcholine = “iums”) or depolarising (suxamethonium)
CEPOD surgery classifications + examples
1 = immediate life or limb saving (ruptured AAA) 2 = urgent (hours) eg compound fracture 3 = expedited (days eg tendon/ nerve injury) 4 = elective
