Anaesthetics Flashcards
(188 cards)
1
Q
How to evaluate a difficult airway?
A
LEMON Look Evaluate (3-3-2) Mallampati score Obstruction Neck mobility
2
Q
How to assess for ventilation difficulty?
A
BONES Beard Obesity No teeth Elderly Snoring hx
3
Q
What is the 3-3-2 rule?
A
3 fingers should fit in mouth
3 fingers from mandible to hyoid (hyoid-mental distance)
2 fingers in superior laryngeal notch (thyroid mouth distance)
4
Q
What are the Mallampati scores?
A
1 = full view of uvula 2 = body + base of uvula 3 = base of uvula 4 = only hard palate + tongue, no other structures visible
5
Q
What are the indications for CBC pre-op?
A
Major surgery needing group + screen or X match
Chronic CV, pulmonary, renal or hepatic disease
Malignancy
Anaemia
Bleeding diathesis
Myelosuppression
Pt <1 y/o
6
Q
What are the indications for sickle cell screen pre-op?
A
Genetically predisposed pt
7
Q
What are the indications for INR + aPTT pre-op?
A
Anticoagulant therapy
Bleeding diathesis
Liver disease
8
Q
What are the indications for electrolytes + creatinine pre-op?
A
HTN Renal disease DM Pituitary or adrenal disease Vascular disease Digoxin Diuretics
9
Q
What are the indications for fasting glucose pre-op?
A
DM
10
Q
What are the indications for ECG pre-op?
A
Heart disease DM SAH/ ICH CVA Head trauma
11
Q
What are the indications for chest xray pre-op?
A
New or worsening resp symptoms
12
Q
What are the ASA grades?
A
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
13
Q
What medications should be stopped pre-op + in what timeframes?
A
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
14
Q
What medications should be adjusted pre-op?
A
Insulin, prednisone, bronchodilators
15
Q
What is the BP target pre-op?
A
<180/110
16
Q
What considerations should be taken pre-op with someone with CAD?
A
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)
17
Q
What advice should be given re smoking pre op?
A
Abstain for 8 weeks pre-op
If unable, 24hrs increases O2 availability
18
Q
What are non-selective BB?
A
Labetalol, nadolol = block both B1 + B2
19
Q
What considerations are involved with asthma?
A
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
20
Q
What increases risk of aspiration?
A
Decreased LOC Delayed gastric emptying (narcotics, DM, non fasted for 8 hrs) Decreased sphincter competence Increased abdo pressure Unprotected airway
21
Q
Fasting guidelines
A
8hrs = meal including meat, fried or fatty food 6hrs = light meal eg toast or infant formula 4hrs = breast milk 2hrs = clear fluids
22
Q
Considerations for pts with haematological disorders
A
Pre-op treatment to increase Hb (iron, erythropoietin)
Modify anti-coagulants
Administer reversal agents if needed
23
Q
Considerations for pts with DM
A
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
24
Q
Considerations for pts with hyperthyroidism
A
Can cause sudden release of thyroid hormone (thyroid storm) so treat with BB and pre-op prophylaxis
25
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
26
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
27
What routine monitoring is required for all cases?
Pulse oximeter, BP, electrocardiography, capnography (for GA + sedation 4-6), agent specific gas monitor
28
What other monitoring should be available?
Temp probe, nerve stimulator, stethoscope, lighting, spirometry, manometer to measure ETT cuff pressure
29
How is anaesthetic depth monitored?
End tidal inhaled anesthetic monitoring, EEG monitoring (Bispectral index monitor)
30
What findings suggest inadequate depth of anaesthesia?
Blink reflex present, HTN, tachycardia, tearing or sweating
31
What elements need monitoring?
```
Anesthetic depth
Oxygenation
Ventilation
Circulation
Temperature
Urine output
```
32
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)
33
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
```
34
What equipment is needed for intubation?
```
Monitors
Drugs
Suction
O2 source + oro/ naso airways
Laryngoscope
ETT
Stylet + syringe for tube cuff inflation
```
35
What meds can be given through the ETT?
```
NAVEL
Naloxone
Atropine
Ventolin
Epinephrine
Lidocaine
```
36
What are the indications for an ETT?
```
Pt airway
Protects against aspiration
Positive pressure ventilation
Pulmonary toilet (suction)
Pharmacological administration
```
37
What is the sizing for LMA?
```
40-50kg = 3
50-70kg = 4
70-100kg = 5
```
38
What is the sizing for ETT?
Male = 8-9mm
Female = 7-8mm
Paed uncuffed >2 = age/ 4 + 4mm
39
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)
40
Where is the laryngoscope tip placed?
In epiglottic vallecula
41
What is the DDx for poor bilateral breath sounds after intubation?
```
DOPE
Displaced ETT
Obstruction
Pneumothorax
Esophageal intubation
```
42
What is the foreign body reflex in the trachea?
Sympathetic response due to stimulation of CN9 + 10
| Causes tachycardia, dysrhythmias, myocardial ischaemia + increased BP
43
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
44
Where should the tip of the ETT be?
Midpoint of trachea, 2cm above carina
| Proximal end of cuff at least 2cm below vocal cords
45
What cm mark should be at the corner of the mouth for the ETT?
Men - 20-23cm
| Women = 19-21cm
46
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
```
47
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
```
48
What to do if intubation unsuccessful after induction?
Call for help
Ventilate with bag mask
Consider returning to spontaneous ventilation/ waking pt
49
What is the goal of O2 therapy?
O2 sats >90%
50
When is cyanosis detected (+ frank cyanosis)?
SaO2 <85%
| Frank cyanosis at <67&
51
What are low flow systems?
0-10L/min
Acceptable if tidal vol 300-700ml, RR <25, consistent ventilation pattern
eg nasal cannula
52
What FiO2 is supplied with a nasal cannula?
At 1-6L/min = 24-44%
53
What are reservoir systems?
Reservoir accumulates O2 eg face mask or non-rebreathe mask
54
What FiO2 is supplied with a face mask + non-rebreathe mask?
Face mask = 55% at 10L
| Non-rebreathe = 80% at 10-15L
55
What are high flow systems?
Flow up to 50-60L
| E.g. venturi mask ranging from 24-50%
56
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
57
What are the airway complications of mechanical ventilation?
Tracheal stenosis, laryngeal oedema
Ventilator induced lung injury (barotrauma)
Nosocomial pneumonia
58
What are the cardiac complications of mechanical ventilation?
Reduced venous return
Reduced cardiac output
Hypotension
59
What are the neuromuscular complications of mechanical ventilation?
Muscle atrophy
| Increased ICP
60
What are the metabolic complications of mechanical ventilation?
Hyperventilation = decreased CO2
| Alkalemia
61
How do you monitor ventilator therapy?
Pulse oximetry, end tidal CO2
| Regular ABGs
62
Pts who develop a pneumothorax while being ventilated need what?
Chest tube
63
How can ventilation help with hypoxaemic resp failure?
Helps improve V/Q match
Provides O2
Recruits atelectatic lung segments
Decreases interpulmonary shunt
64
How can ventilation help with hypercapnic resp failure?
Augments alveolar ventilation
Decreases work of breathing
Allows resp muscles to rest
65
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
66
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
67
What is synchronous intermittent mandatory ventilation?
Ventilator provides controlled breaths (either with VC or PCV)
Pts can breathe spontaneously between controlled breaths
68
What is pressure supported ventilation?
Pt initiates all breaths + ventilator supports each breath with pressure
Useful for weaning off ventilator
69
What is high frequency oscillatory ventilation?
High breathing rate, very low tidal volumes
| Used in neonatal/ paeds resp failure
70
What is non-invasive positive pressure ventilation?
BiPAP + CPAP
71
Causes of decreased end tidal CO2?
```
Hyperventilation
Hypothermia
Decreased pulmonary blood flow
V/Q mismatch
PE
Pulmonary edema
Air embolism
```
72
Causes of increased end tidal CO2?
Hypoventilation
Hyperthermia
Improved pulmonary blood flow eg after resuscitation or hypotension
Low bicarbonate
73
Causes of hypothermia intra-op
Environment
| Open wound
74
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
75
Causes of hyperthermia intra op
```
>37.5
Drugs - atropine
Blood transfusion reaction
Infection
Thyrotoxicosis
Malignant hyperthermia
Over-zealous warming efforts
```
76
Which cardiac arrests are shockable vs not?
```
Shockable = VT + VF
Not = PEA + asystole
```
77
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)
```
78
What are the SVTs?
```
Narrow complex
Sinus tachycardia
AF/ flutter
Accessory pathway mediated
Paroxysmal atrial tachycardia
```
79
What are the wide complex tachycardias?
VT, SVT with aberrant conduction
80
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
81
What is the boundary for tachy + bradycardia?
Tachy >150
| Brady <50
82
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
83
What are the causes of intra-op shock?
```
SHOCA
Sepsis or spinal
Hypovolaemia/ haemorrhagic
Obstructive
Cardiogenic
Anaphylactic
```
84
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
```
85
What is the total requirement for fluids?
Total = maintenance + deficit + ongoing loss
86
What is the average total requirement due to what losses?
2500 =
200 GI loss
800 insensible losses (resp, sweat)
1500ml urine
87
What should the maintenance rate not exceed?
No more than 3ml/kg/hr
88
When are there increased requirements for fluids?
```
Fever
Sweating
GI losses
Adrenal insufficiency
Hyperventilation
Polyuric renal disease
```
89
When are there decreased fluid requirements?
Anuria
SIADH
Highly humidified atmospheres
CHF
90
What are the maintenance electrolyte requirements?
```
Na+ = 3 mEq/kg/d
K+ = 1 mEq/kg/d
```
91
How much is the total body water?
60% of male body weight
| 50% of female body weight
92
What does the total Na content + [Na+] determine?
```
Content = ECF volume
Conc = ICF volume
```
93
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)
```
94
How should chronic hyponatraemia be corrected?
Slowly over 48hrs to avoid central pontine myelinosis
95
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
```
96
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
97
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
98
What is the blood volume of infants, males + females?
Blood volume:
Infant = 80ml/kg
Female = 60ml/kg
Male = 70ml/kg
99
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
```
100
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
```
101
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
102
Which volatile anaesthetics are most soluble to least soluble?
Halothane > Isoflurane > Sevoflurane > Desflurane > NO2
103
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
104
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
105
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
106
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
```
107
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
108
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
```
109
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
```
110
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
```
111
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
```
112
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
```
113
What is the MAC + effect cardiac system of N20?
```
MAC = 104
CVS = decrease HR in paeds pts with existing heart disease
```
114
What is MAC?
Minimum alveolar conc needed to prevent movement in 50% of pts in response to surgical stimulus
115
What factors increase MAC?
Chronic alcohol use, hyperthyroidism, hyperthermia, stimulants, young age
116
What factors decrease MAC?
Acute alcohol intoxication, hypothermia, sedating drugs, advanced age, drugs (opioids + benzos)
117
How does MAC change for every decade of life?
Decreases by 6%
118
What is MAC-intubation?
1.3
119
What is MAC-block adrenergic response?
1.5
120
What is MAC-awake?
0.3-0.4
121
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
122
Contraindications to SCh?
MH, myotonia, high risk for hyperkalaemia
| Relative: myasthenia gravis, open eye injury
123
What is the intubating dose, onset, duration + metabolism of mivacuronium?
Intubating dose = 0.2
Onset = 2-3 mins
Duration = 15-25 mins
Metabolism = cholinesterase
124
What is the mode of action of non-depolarising muscle relaxants?
Competitive blockage of postsynaptic ACh receptors preventing depolarisation
125
What is the order or non-depolarising muscle relaxants, from short to long acting?
```
Short = Mivacuronium - Rocuronium
Int = Vecuronium - Cisatracurium
Long = Pancuronium
```
126
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)
127
What is the intubating dose, onset, duration + metabolism of vecuronium?
Intubating dose = 0.1
Onset = 2-3 mins
Duration = 45-60 mins
Metabolism = Liver
128
What is the intubating dose, onset, duration + metabolism of cisatracurium?
Intubating dose = 0.2
Onset = 3 mins
Duration = 40-60 mins
Metabolism = Hofmann eliminations
129
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)
130
Which non-depolarising muscle relaxants release histamine?
Mivacuronium
131
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
132
What is the action of reversal agents?
Sugammadex = selective relaxant bnding agent
| Neostigmine, edrophonium = ACh inhibitors
133
Dose, recommended anticholinergic + onset of pyridostigmine?
Slow onset
0.1-0.4 mg/kg
Give with glycopyrrolate 0.05mg
134
Dose, recommended anticholinergic + onset of neostigmine?
Intermediate onset
0.04-0.08 mg/kg
Give with glycopyrrolate 0.2 mg
135
Dose, recommended anticholinergic + onset of edrophonium?
Intermediate onset
0.5-1 mg/kg
Give with atropine 0.014mg
136
What is the dose + action of sugammadex?
Action - encapsulates roco + vecu + decreases amount of agent available at NMJ
2-16 mg/kg
137
What are the complications of early extubation?
Aspiration
| Laryngospasm
138
What are the complications of late extubation?
transient vocal cord incompetence, oedema, pharyngitis, tracheitis
139
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)
140
What is regional anaesthesia?
LA applied around peripheral nerve
| No CNS depression
141
What landmarks indicate L4 + T7?
```
L4 = between iliac crests
T7 = tip of scapula
```
142
What is the classic presentation of a dural puncture headache?
Onset 6h - 3d after puncture
Postural component
Occipital or frontal localisation
+/- tinnitus, diplopia
143
What structures are penetrated outside to inside for a spinal/ epidural?
```
Skin
SC fat
Supraspinous ligament
Interspinous ligament
Ligamentum flavum
EPIDURAL
Dura
Arachnoid
SPINAL
```
144
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
145
Mode of action of LA
Bind to receptors on cytosolic side of Na+ channel, inhibiting Na+ flux + blocking impulse conduction
146
How is LA metabolised?
```
Esters = broken down by plasma + hepatic esterases, excreted by kidneys
Amides = broken down by hepatic oxidases (P450) + excreted by kidneys
```
147
What are the types of LA?
```
Ester = procaine, tetracaine
Amide = lidocaine, bupivacaine
```
148
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
149
What is the order of duration, from short to long, of LA?
Short: chloroprocaine (15-30 mins)
Lidocaine
Bupivacaine
Ropivacaine (2-8hrs)
150
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
```
151
What are the effects on the CVS of LA toxicity?
Vasodilation
Hypotension
Decreased contractility
Bradycardia
152
What is the treatment for LA toxicity?
```
Get help
100% O2, manage ABCs
Diazepam to prevent seizures
Manage arrhythmias
Intralipid 20%
```
153
Where not to use LA with epinephrine?
```
Ears
Fingers
Toes
Penis
Nose
```
154
How to treat PONV?
```
Dimenhydrinate (Gravol)
Metoclopramide (Maxeran) - not with bowel obstruction
Prochlorperazine (Stemetil)
Ondansetron (Zofran)
Granisetron (Kytril)
```
155
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
156
How can post-op HTN be treated?
IV nitroglycerin, hydralazine, CCB ot BB
157
What is the definition of pain + nociception?
```
Pain = perception of nociception, occurs in brain
Nociception = detection, transduction, transmission of noxious stimuli
```
158
How is pain classified?
Temporal eg acute vs chronic
| Mechanism eg nociceptive vs neuropathic
159
When should NSAIDs be used with caution?
```
Asthma
Coagulopathy
GI ulcers
Renal insufficiency
Pregnancy, 3rd trimester
```
160
What are the common SE of opioids?
```
N/V
Constipation
Sedation
Pruritus
Abdo pain
Urinary retention
Resp depression
```
161
What to consider prescribing alongside opioids?
Breakthrough dose
Anti-emetics
Laxative
162
What are the PCA parameters?
```
Loading dose
Bolus dose
Lockout interval
Continuous infusion
Maximum 4h dose
```
163
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
```
164
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
```
165
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
166
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
```
167
What CVS differences are there for paeds?
High HR + low BP
| CO is dependant on HR
168
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
169
What is malignant hyperthermia?
Hypermetabolic disorder of skeletal muscle
Uncontrolled increase in intracellular Ca+
Autosomal dominant
Triggered by inhalational agents + SCh
170
What are the signs of MH?
```
Increased O2 consumption
Rise in ETCO2
Increase in minute ventilation
Tachycardia
HTN
Rigidity
Hyperthermia
```
171
What are the muscular symptoms of MH?
Trismus (masseter spasm)
Rhabdomyolysis
Rigidity
172
Complications of MH
```
Coma
DIC
Rhabdomyolysis
Hyperkalaemia
ARDS
```
173
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
```
174
What is abnormal pseudocholinesterase?
Hydrolyzes SCh + mivacurium
| Abnormal = prolonged muscular blockage
175
When are naso + oropharyngeal airways useful?
Naso - better tolerated but not to be used in ?basal skull fracture
176
What is the most common cause of obstruction when a pt is under GA?
Tongue
177
How do you measure endotracheal tube size?
Internal diameter in mm
178
What is the best indicator that the endotracheal tube is in place?
Expired CO2
179
What is the WHO checklist for surgery?
Checklist for surgery safety
Before induction of anaesthesia
Before skin incision
Before patient leaves operating room
180
How to measure oro + nasopharyngeal airways?
```
Oro = incisors to angle of jaw
Naso = tip of nose to tragus of ear
```
181
What are supraglottic airways?
Sit abutting the larynx above vocal cords
Not definitive due to risk of aspiration
Good for short/ low risk procedures
182
What is a laryngeal mask airway?
Reusable supraglottic device
183
What is an iGel?
Single use supraglottic device
184
What is Yankaur suction used for?
To clear oropharynx
185
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
186
What is a bougie used for?
Can be moulded + used for difficult airways
187
What are neuromuscular blockers + the 2 types?
Muscle relaxants used in GA
| Non-depolarising (compete with acetylcholine = "iums") or depolarising (suxamethonium)
188
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
```
