Anaesthetics Flashcards
3 components of anaesthesia?
hypnosis (amnesia)
analgesia
muscle relaxation (akinesis)
3 levels of hypnosis? how do anaesthetic agents therefore act?
awake (LA)
sedation (sedation)
asleep (GA)
3 local techniques:
local - minor surgery - laceration repair
regional - target specific nerves (brachial plexus or sciatic) - for post-op pain relief
neuraxial - spinal/epidural - intra-op, post-op use
what is the difference between spinals and epidurals?
Spinal (subarachnoid block) goes through both ligaments and dura to CSF via an injection at lumbar region, single bolus, faster onset, smaller dose, anaesthetic only
Epidural - needle goes between ligaments and dura and a catheter is passed
continuous infusion, slow onset, larger dose required, anaesthesia+analgesia, T or L spine
where are spinals and epidurals incisions done?
below the highest nerve root affected by the block
normally this is T10 dermatome - umbilicus
why is incision for epidurals/spinals not done above this level?
GA would be required
also epidurals would be insufficient post-op analgesia
MODA: LA:
reversibly blocks Na+ channels
inhibits generation of action potentials in nerve cells
smaller diameter, unmyelinated fibres blocked first
order of block: L.A:
b fibres (autonomic - vasoconstriction)
C and A(d) - pain and temp
A(b) - light touch and pressure
A(a) and A(Y) - motor and proprioception
what is often used in combination with LA? why?
adrenaline - vasoconstriction leads to reduced bleeding and prolonged effects of the LA through reduced absorption from tissues
where should adrenaline not be used?
in end arteries such as fingers
examples of L.A?
lidocaine
bupivicaine
lidocaine onset and duration, when used?
immediate onset, lasts 15m
small procedures - laceration repairs, chest drains, large cannulae
bupivicaine onset and duration, when used?
regional, spinal, epidural
10m onset - lasts 2h anaesthetic, 12-24h as analgesic
what do epidural infusions have running through them commonly and what should this indicate?
opioids
do not prescribe further opioids
what does induction and maintenance mean regarding general anaesthesia?
induction - sending to sleep
maintenance - keeping asleep
how are hypnotic drugs given?
inhaled or IV
3 examples of inhalational hypnotic drugs:
Isoflurane - cheapest - maintains sedation
Desflurane - maintains sedation - quick wears off
Sevoflurane - induces+/-maintains sedation
3 examples of IV hypnotic drug:
Propofol - quick onset - commonest - also antiemetic - fast redistribution (fast recovery of consciousness)
Thiopenthal - quick - emergency anaesthetics
Ketamine - used in CVS instability - also analgesic
pros and cons of induction via inhaled and IV:
IV - commoner, requires cannula, rapid onset, depresses airway reflexes, apnoea common
Inhaled - good for needle phobics, slow onset, irritates airway, usually keep breathing
once GA has taken effect, patients often stop breathing, how is their airway managed? (2)
spontaneous breathing
controlled ventilation
t1rF caused by what specific problem?
alveolar collapse or fluid in alveoli
name an agent which reverses the effects of midazolam?
Flumazenil
which drug is hepatotoxic and also can harm theatre staff if accumulated use?
halothane
name an anaesthetic agent which has anti emetic properties
propofol
Propofol features:
GABA receptor agonist
Rapid onset of anaesthesia
Pain on IV injection
Rapidly metabolised with little accumulation of metabolites
Proven anti emetic properties
Moderate myocardial depression
Widely used especially for maintaining sedation on ITU, total IV anaesthesia and for daycase surgery
Sodium thiopentone
features:
Extremely rapid onset of action making it the agent of choice for rapid sequence of induction Marked myocardial depression may occur Metabolites build up quickly Unsuitable for maintenance infusion Little analgesic effects
Ketamine features:
NMDA receptor antagonist
May be used for induction of anaesthesia
Has moderate to strong analgesic properties
Produces little myocardial depression making it a suitable agent for anaesthesia in those who are haemodynamically unstable
May induce state of dissociative anaesthesia resulting in nightmares
Etomidate features:
Has favorable cardiac safety profile with very little haemodynamic instability
No analgesic properties
Unsuitable for maintaining sedation as prolonged (and even brief) use may result in adrenal suppression
Post operative vomiting is common
A seventy-two-year-old woman with rheumatoid arthritis is recovering on the ward 6 days following a left hemi-colectomy for a tumour in the descending colon. She complains to the nurse looking after her that she has developed pain in her abdomen. The pain is diffuse and came on suddenly but has gradually been getting worse since onset. She ranks it an 8/10. She has not opened her bowels or passed flatus since the procedure. dx? iX?
anastamotic leak
diagnosed with abdominal CT
what is contraindication of using LMA?
being non-fasted
LMA doesn’t isolate the airway and cannot provide control against gastric reflux - risk of asapiration
also obesity (morbid)
contraindications for nasopharyngeal airway?
Basilar skull fracture and underlying coagulopathy
periorbital ecchymosis and clear fluid leaking from one nostril
which manouvres can open the airway? (3)
head tilt
chin lift
jaw thrust
is xray needed commonly pre-op in patients?
no
what do nice commonly recommend ix for pre-op?
ECG in over 65
renal disease - FBC, ECG
On approaching the bedside of an elderly obese man, you find him quite drowsy. When you call out his name, you hear a grunting noise. You call out for the nurse’s help. Oxygen saturations are 82% on air.
What is the next step in the immediate management of this patient?
head tilt, chin lift, jaw thrust first
A 17-year-old man undergoes an elective right hemicolectomy. Post operatively he receives a total of 6 litres of 0.9% sodium chloride solution, over 24 hours. Which of the following complications may ensue?
hyperchloric acidosis
A 45-year-old woman is admitted with acute pyelonephritis. She requires intravenous access for antibiotics and maintenance fluids as she is currently taking limited fluids due to vomiting. She is haemodynamically stable. which cannula?
1x20G cannula
A 3-year-old is injured in a road traffic accident and is hypotensive and tachycardic due to a suspected splenic injury, she is peripherally shut down. how to get access?
Intraosseous
A 73-year-old man with Dukes C colonic cancer requires a long course of chemotherapy. He has poor peripheral veins. access??
Hickmann line
which site is preferred for central line access?
internal jugular as femoral high infection rate
50M RTC The helicopter emergency service attends the scene. GCS is 7 (E2, V1, M5) and he has no air entry on the left side of the chest, with an open fractured neck of femur on the right hand side.
Temperature: 37.6ºC.
Heart rate: 110bpm.
Blood pressure: 60/40mmHg.
SpO2: 95% on air.
Respiratory rate: 22/min.
His fractured femur is reduced at the scene but in view of his low GCS the decision is made to intubate him at the scene. What is the best agent for induction of anaesthesia?
Ketamine
as good for those who are haemodynamically unstable
healthy, non-smoker, minimal or no alcohol use - ASA?
1
Including, but not limited to, well-controlled diabetes, hypertension. Social drinker. Smoker - ASA?
2
ncluding, but not limited to: poorly control diabetes/asthma, hypertension. BMI > 40. Previous MI > 6m ago. ASA?
3
also ESRD
ncluding, but not limited to: recent MI (<3m), severe reduction in ejection fraction - ASA?
4
Including, but not limited to: ruptured AAA, massive trauma. ASA?
5
cause of RLL consolidation in pt who has been ventilated post op for 14/7?
tracheo-oesophageal fistula formation
A 22-year-old lady undergoes a total thyroidectomy for Graves disease. 6 hours post operatively she develops respiratory stridor and develops a small haematoma in the neck - mx?
immediate reoval of sx clips on ward
44-year-old lady undergoes a total thyroidectomy for recurrent multinodular goitre. 3 days post operatively she is still troubled by a hoarse voice. mx?
laryngoscopy
48-year-old lady undergoes a redo thyroidectomy for a multinodular goitre. 24 hours post operatively she develops oculogyric crises and diffuse muscle spasm. mx?
iv calcium - hypocalcaemic tetany caused this
pts taking prednisolone long term - what important thing needs prescribing pre-op?
hydrocortisone
why is Suxamethonium is contraindicated for patients with penetrating eye injuries ?
increases intra-ocular pressure
25-year-old lady has developed disseminated intravascular coagulation due to an acute peripartum haemorrhage. After general resuscitation measures, what treatment should be administered first?
FFP
what can cause hypovolaemia and electrolyte disturbances BEFORE nausea and vomiting becomes apparent?
ileus
what is disrupted in ileus?
peristalsis
43M surgical ward four days after a laparotomy and right hemicolectomy for cancer. Temperature of 38.2ºC and is tachycardic at 121 bpm and tachypnoeic at 24 breaths per minute. Abdomen is soft and not distended but tender around his midline wound. There is some discharge seeping through the dressing. His chest is clear and he has no signs of a deep vein thrombosis.
Cause of this man’s raised temperature?
wound infection
where is intraosseus access commonly gained?
proximal tibia
distal femur, humeral head also used sometimes
The WHO Surgical Checklist identifies the following stages of a surgical procedure:
Sign in - before induction
Time out - before the first incision
Sign out - after last incision and before patient leaves the operating room
A 22-year-old female is extubated following an uncomplicated laparoscopic appendicectomy. However, no respiratory effort is made and she is re-intubated and ventilated. She is monitored in the intensive care unit and all observations are normal. She is weaned from the ventilator 24 hours later successfully. What complication has occurred?
suxamethonium apnoea
small subset of the population has an autosomal dominant mutation, leading to a lack of the specific acetylcholinesterase in the plasma which acts to break down suxamethonium, terminating its muscle relaxant effect. Therefore, the effects of suxamethonium are prolonged and the patient needs to be mechanically ventilated and observed in ITU until the effects of suxamethonium wear off.
suxamethonium features:
Depolarising neuromuscular blocker
Inhibits action of acetylcholine at the neuromuscular junction
Degraded by plasma cholinesterase and acetylcholinesterase
Fastest onset and shortest duration of action of all muscle relaxants (RSI)
Produces generalised muscular contraction prior to paralysis
Adverse effects include hyperkalaemia, malignant hyperthermia and lack of acetylcholinesterase
atracurium features:
Non depolarising neuromuscular blocking drug
Duration of action usually 30-45 minutes
Generalised histamine release on administration may produce facial flushing, tachycardia and hypotension
Not excreted by liver or kidney, broken down in tissues by hydrolysis
Reversed by neostigmine
vecuronium features:
Non depolarising neuromuscular blocking drug
Duration of action approximately 30 - 40 minutes
Degraded by liver and kidney and effects prolonged in organ dysfunction
Effects may be reversed by neostigmine
pancuronium features:
Non depolarising neuromuscular blocker
Onset of action approximately 2-3 minutes
Duration of action up to 2 hours
Effects may be partially reversed with drugs such as neostigmine
lidocaine features:
An amide
Local anaesthetic and a less commonly used antiarrhythmic (affects Na channels in the axon)
Hepatic metabolism, protein bound, renally excreted
Toxicity: due to IV or excess administration. Increased risk if liver dysfunction or low protein states. Note acidosis causes lidocaine to detach from protein binding. Local anesthetic toxicity can be treated with IV 20% lipid emulsion
Drug interactions: Beta blockers, ciprofloxacin, phenytoin
Features of toxicity: Initial CNS over activity then depression as lidocaine initially blocks inhibitory pathways then blocks both inhibitory and activating pathways. Cardiac arrhythmias.
Increased doses may be used when combined with adrenaline to limit systemic absorption.
cocaine features;
Pure cocaine is a salt, usually cocaine hydrochloride. It is supplied for local anaesthetic purposes as a paste.
It is supplied for clinical use in concentrations of 4 and 10%. It may be applied topically to the nasal mucosa. It has a rapid onset of action and has the additional advantage of causing marked vasoconstriction.
It is lipophillic and will readily cross the blood brain barrier. Its systemic effects also include cardiac arrhythmias and tachycardia.
Apart from its limited use in ENT surgery it is otherwise used rarely in mainstream surgical practice.
bupivicaine feautres:
Bupivacaine binds to the intracellular portion of sodium channels and blocks sodium influx into nerve cells, which prevents depolarization.
It has a much longer duration of action than lignocaine and this is of use in that it may be used for topical wound infiltration at the conclusion of surgical procedures with long duration analgesic effect.
It is cardiotoxic and is therefore contra indicated in regional blockage in case the tourniquet fails.
Levobupivicaine (Chirocaine) is less cardiotoxic and causes less vasodilation.
prilocaine features:
Similar mechanism of action to other local anaesthetic agents. However, it is far less cardiotoxic and is therefore the agent of choice for intravenous regional anaesthesia e.g. Biers Block.
During the operation her temperature is recorded at 34.8 ºC. Her blood pressure is 98/57 mmHg. The surgeon notes that the patient is bleeding more than would be expected.
Which of the following may account for the excessive bleeding?
hypothermia - clotting factors function at specific temp and pH so deviation from that means ++bleed
sign in checklist:
Patient has confirmed: Site, identity, procedure, consent
Site is marked
Anaesthesia safety check completed
Pulse oximeter is on patient and functioning
Does the patient have a known allergy?
Is there a difficult airway/aspiration risk?
Is there a risk of > 500ml blood loss (7ml/kg in children)?
39F obese undergoes an elective laparoscopic cholecystectomy for gallstone disease. Day 1 post-op patient is complaining of severe right upper quadrant pain. Tachycardic, normotensive and apyrexial. RUQ tender to palpation but there is no evidence of jaundice. The intra-abdominal drain in-situ has a small volume of green liquid draining from it. What post-operative complication is most likely?
biliary leak
The anaesthetist elicits a family history from the patient, which reveals that his father and paternal grandfather both experienced malignant hyperthermia following the administration of a general anaesthetic.
His mother and his paternal grandmother have never had an adverse reaction following a general anaesthetic.
What is the chance of this patient having the same reaction after a general anaesthetic? (AD)
50%
malignant hyperthermia causes:
halothane
suxamethonium
mx of malignant hyperthermia:
dantrolene - prevents Ca2+ release from the sarcoplasmic reticulum
what potential, and serious, cause of new onset atrial fibrillation following gastrointestinal surgery?
anastamotic leak
look for feculent matter in drain
what classically presents with severe abdominal pain and the passage of bloody stools.?
ischemic colitits
75m SAU prior to an elective Hartmann’s procedure in 7 days due to bowel cancer. He has a past medical history of atrial fibrillation, hypertension and previous cerebrovascular accident. Your registrar asks you to review him prior to his procedure next week. You notice that he is currently taking warfarin and his INR today is 2.6. His remaining blood tests are normal. What is the most appropriate management for his anticoagulation peri-operatively?
stop warfarin and commence LMWH tx dose
patient is administered local anaesthetic at the end of an operation. The surgeon infiltrates 20ml of 2% lidocaine.
How many mg of lidocaine does this amount to?
A 2% strength liquid medicine means that 2g of the drug are dissolved in 100ml
= 400mg
what autosomal dominant disorder presenting as a hypermetabolic crisis characterised by an increased end-tidal carbon dioxide [ETCO2] (hypercapnia), tachycardia, muscle rigidity, rhabdomyolysis, hyperthermia, and arrhythmia.??
malignant hyperthermia
anastamotic leak mx:
surgical emergency and patients must be taken back to theatre as soon as possible
what is dehydration a risk factor for in surgical prep?
VTE
Isolated fever in well patient in first 24 hours following surgery? Think..
physiological reaction to operation
how should TPN be administered?
Total parenteral nutrition should be administered via a central vein as it is strongly phlebitic (subclavian)
how to generally reduce abdominal adhesions in surgery?
laparoscopic approach vs open
72-year-old male is recovering from a partial colectomy that he had 3 days ago. The patient complains of worsening pain at the wound site. On closer examination there is pink serous discharge, separation of the wound edges and bowel can be seen protruding. The patient has no other obvious symptoms. How should this patient immediately be managed?
senior help immediately
large sterile swab soaked in 0.9% saline can be used while waiting for senior help to arrived.
?sepsis
41-year-old man is assessed on the orthopaedic ward with pyrexia and shortness of breath. He had an intramedullary nail to fix a fracture of his right tibia 7 days ago. Which of the following is most likely the cause of his delayed (> 5 days) post-operative pyrexia?
VTE
commonly 5-10days post-op
28-year-old man is comatose, from head injuries, on the neurosurgical intensive care unit. There is no evidence of a basal skull fracture. He is recovering well and should be extubated soon. - feeding?
NG feed
56-year-old man has undergone a potentially curative oesophagectomy for carcinoma. feeding?
jejunostomy
43-year-old man is recovering from a laparoscopic low anterior resection with loop ileostomy. feeding?
normal oral intake
pre-op assessment includes:
hx of PC surgical, medical, anaesthetic hx systems review DH and allergies - HRT, OCP smoking, weight and exercise tolerance
what pre-op assessment ranked 1-4 assesses the upper airway access based on visibility of the oral pharynx?
mallampti
ranging from complete visualization including tonsilar pillars to no visualization with the uvula pressed against the tongue.
what other measures can be used to assess upper airway access apart from mallampti?
thyromental distance
sternomental distance
ASA 6 means ?
brain dead. organ harvest
NCEPOD classification determines how quickly an op should occur:
1 - immediate life/limbs saving intervention - minutes (AAA)
2 - urgent acute deterioration threat to life/limb - hours (perforation)
3 - expediated - stable needing early intervention - days (tumour removal)
4 - planned elective
grounds for operation cancellation:
Current respiratory tract infection Poor control of drug therapy Recent MI Poor bloodwork Inadequate preparation Untreated hypertension, uncontrolled AF Logistical issues
whole process of a GA: (7)
Preoxygenation Opioid Induction agent Inhalational agent Bag valve mask ventilation Muscle relaxant Endotracheal intubation
whole RSI process: (3)
why is it used, example of drug
Reduces risk of aspiration Preoxygenation Sellick’s manoeuvre Induction then immediately muscle relaxant Classic: thiopentone + suxamethonium
mx of LA overdose?
Stop injecting LA
HELP
A: maintain airway, ?ET tube
B: 100% oxygen, adequate lung ventilation
C: IV access, haemodynamic stability
D: control seizures (benzos/thiopentone/propofol)
E: intralipid
cx of poor post-op pain relief?
pneumonia
ddx post-op fever by day?
Day 1-2: ‘Wind’ - Pneumonia, aspiration, PE
Day 3-5: ‘Water’ - UTI (especially if catheterised)
Day 5-7: ‘Wound’ - site infection/ abscess formation
Day 5+: ‘Walking’ - DVT or PE
Any time: Drugs, transfusion reactions, sepsis, line contamination.
67F oesophagogastrectomy for carcinoma of the distal oesophagus. She complains of chest pain. The following day there is brisk bubbling into the chest drain when suction is applied. dx?
air leak
20M ITU following a difficult appendicectomy for perforated appendicitis with pelvic and sub phrenic abscesses. Now deteriorated further and developed deranged liver function tests.dx?
portal vein thrombosis
63M Ivor - Lewis oesophagogastrectomy for ca of the distal oesophagus. The following day a pale opalescent liquid is noted to be draining from the right chest drain. dx?
chyle leak
lymph related
Four days after undergoing a right hemicolectomy for colon cancer, a 67-year-old woman develops vomiting. On examination she has a distended abdomen and no bowel sounds. Her temperature is 36.8 ºC, her blood results show the following: crp up, wcc normal. dx?
paralytic ileus
which pts very sensitive to non-depolarising agents??
myasthenia gravis
post-colorectal sx - ileus mx?
NG tube NBM
elective total hip replacement surgery NICE recommend commencing a low molecular weight heparin when?
6-12h after surgery
when stop taking COCP before surgery (elective)?
4 weeks
vte baby
Cystectomy - blood products needed to prepare before?
Cross-match 4-6 units depending on local protocols
Appendicectomy - blood products needed to prepare before?
group and save only
also lap choly, elective C-S
Elective abdominal aortic aneurysm (AAA) repair
- blood products needed to prepare before?
cross-match 4-6 units depending on local protocols
(Total gastrectomy, oophorectomy, oesophagectomy
Elective AAA repair, cystectomy, hepatectomy)
post op drop off of urine output - mx?
fluid challenge
A 63-year-old man has been on the intensive care unit for a week with adult respiratory distress syndrome complicating acute pancreatitis. He has required ventilation and is still being mechanically ventilated.
airway?
tracheostomy
used for long term weaning
A 23-year-old man is undergoing an inguinal hernia repair as a daycase procedure and is being given sevoflurane.
airway?
LMA
A 48-year-old man is due to undergo a laparotomy for small bowel obstruction.
airway?
endotracheal tube
use of which meds will slow bone healing?
NSAIDs
A 49-year-old man is having an elective repair of a right-sided inguinal hernia under general anaesthetic. What is the most appropriate advice to give him about eating and drinking before the operation?
no food for 6h before no clear fluids for 2h before
black coffee included under clear fluids
A 20-year-old African lady undergoes an open appendicectomy. She is reviewed for an unrelated problem 8 months later. Wound site is covered by shiny dark protuberant scar tissue that projects beyond the limits of the skin incision. underlying process?
keloid scar
extend beyond the limits of the incision
During a surgical ward round you are asked to request a nurse cleans a patient’s surgical wound when the dressing is changed. The patient is 36 hours post surgery. According to NICE guidelines, what is the most appropriate substance to use to clean the wound?
sterile saline
<48h
can shower/tap water after 48h
how to advise DM patients re surgery pre-op?
should be first on list to avoid poorly controlled BMs
Avoidance of using hypotonic (0.45%) in paediatric patients - risk of
hyponatraemic encephalopathy
A 24-year-old female is due to undergo urgent surgery after sustaining traumatic injuries to her left leg in a car crash. She has a family history of malignant hyperpyrexia and last ate solid food 90 minutes ago.
what is unsafe to use in her?
LMA - risk of aspiration
cannulating a DM patient?
NOT in the foot you idiot
colonoscopy - preparation?
bowel prep - laxatives the day before
don’t eat for 24h before
75M orthopaedic ward for an elective hip replacement. He has been assessed for VTE prophylaxis. Apart from the operation and his age he does not have any additional risk factors and he does not have any risk factors for bleeding. What is the recommended VTE prophylaxis measures for this gentleman?
TED stockings + dalteparin starting 6h post-op
