Anaesthetics and Acute Care Flashcards
Malignant Hyperthermia
Hyperpyrexia and muscle rigidity following anaesthetic
RF - AD susceptibility (excessive Ca2+ release from SR)
Causes - halothane, suxamethonium
Inv - ^CK, contracture tests
-> dantrolene (prevents calcium release)
Acute Limb Ischaemia
Causes - thrombus (atherosclerosis) or embolus (AF, recent MI)
= pale, pulseless, painful, paralysis, paresthesia or perishingly cold
Inv - handheld arterial doppler, ABPI
-> A-E, IV opioids, IV UH, vascular review, thrombolysis/ embolectomy/ angioplasty/ bypass/ amputation
Compartment syndrome
Raised pressure within a closed space, compromises tissue perfusion, necrosis
Causes - supracondylar and tibial shaft fractures
= excessive pain on movement (incl passive), use of breakthrough analgesia, paralysis of the muscle group, pallor, may still have pulses
Inv - intercompartmental pressure (>40mmHg to diagnose), normal XR
-> fasciotomy, IV fluids for myoglobinuria
Wallaces Rule of Nines
Each of the following represents 9% TBSA
Head and neck
Each arm
Each anterior leg
Each posterior leg
Anterior chest
Posterior chest
Anterior abdo
Posterior abdo
Palms = 1%
Lund and Browder chart is more accurate
Organophosphate Poisoning
Inhibition of acetylcholinesterase (^nicotinic and cholinergic), farmers
= Dumbels
Defecation
Urination
Miosis (small)
Bradycardia, v BP
Emesis
Lacrimation
Salivation, sweating
-> atropine
Ecstasy OD
= agitated, anxious, confused, ataxia, hyperthermia, rhabdomyolysis, ^HR, ^BP, v Na
-> supportive, may use dantrolene for temp
Ethylene Glycol
Alcohol used as coolant/ antifreeze
= three stages
1 - alcohol intoxication symptoms
2 - metabolic acidosis (high anion gap)
3 - AKI
-> fomepizole (alcohol dehydrogenase inhibitor), haemodialysis if refractory
LSD
Synthetic hallucinogen, potent psychoactive compound
= variable, impaired judgement, amplifies current mood, withdrawn, drug-induced psychosis, may get palp, dry mouth, tremor, ^HR, ^BP, mydriasis, fever, resp arrest
-> calm then, benzos, anti-psych
Methanol Poisoning
Due to formic acid build up
= alcohol symptoms + blindness
-> fomepizole, haemodialysis if fails, folinic acid (v eyes)
Paracetamol OD
RF - increased hepatotoxicity if taking cyp inducers, malnourished (acute alcohol may protect)
-> activated charcoal if present <1hr, N-acetylcysteine infused over 1hr
Acetylcysteine if
- staggered OD
- above treatment line (100 at 4hrs, 15 at 15hrs)
- 8-24hrs had >150mg/kg
- >24hrs with jaundice/ hepatic tenderness/ ^ALT
Comp - anaphylactoid reaction (stop, restart at slower rate, non-IgE mediated mast cell release)
Prog - pH <7.3 at 24hrs for liver transplant (KCH)
Salicylate OD
= hyperventilation (resp centre stim), tinnitus, sweating, n+v, seizures
Inv - mixed respiratory alkalosis and met acidosis
-> charcoal <1hr, urinary alkalinisation (IV sodium bicarb), haemodialysis
Tricyclic OD
E.g., amitriptyline, clomipramine, dosulepin, imipramine
= anti-Ach early (mydriasis, blurry), arrhythmias, seizures
Inv - ABG (met acidosis), ECG (sinus tachy, broad QRS, ^QT)
-> IV bicarb
Opioid OD
E.g., morphine, buprenorphine, methadone
= runny nose, pinpoint pupils, drowsy, watering eyes, yawning, needle tracks
-> naloxone in acute OD, methadone/ buprenorphine for opioid detox
LA Toxicity
-> IV 20% lipid emulsion
Adrenaline can be added to prolong the duration of action at the injection site, permits higher dose of LA
Beta-blocker OD
= v HR, v BP, HF, syncope
-> atropine if brady, glucagon if resistant
Carbon monoxide poisoning
High affinity for Hb and myoglobin, left-shift of oxygen dissociation curve
= headache, n+v, vertigo, confusion, subjective weakness, pink skin, fever, arrythmia, coma, death
Inv - falsely high sats, ABG/VBG, carboxyhaemoglobin levels (<3% normal, <10% smokers), ECG
-> 100% high-flow oxygen via a non-rebreather mask for at least 6hrs, hyperbaric oxygen
Antidotes:
BNZD
Lithium
Iron
Cyanide
Lead
BNZD - Flumazenil if severe (GABA ant, risk of seizures)
Lithium - volume resus if mild, haemodialysis if severe
Iron - desferrioxamine
Cyanide - hydroxocobalamin
Lead - penicillamine, calcium edetate, dimercaprol
Pain Management
Analgesic Ladder
1 - non opioid
2 - weak opioids e.g., codeine, tramadol
3 - strong opioids e.g., morphine, oxycodone
Post Op:
Patient controlled analgesia - IV morphine infusion
Pain Physiology
Nociceptors detect pain, two fibres to transmit the signal
C Fibres - small diameter, slow and dull
A delta - myelinated, larger, sharp and localised
Enter the CNS up the ST tract
Post-Op Pyrexia
0-5 days:
Atelectasis
Cellulitis
UTI
Physiological (systemic inflam, <24hrs)
Blood transfusion
5+ days
Pneumonia
VTE
Wound infection
Anastomotic leak
Propofol
GABA agonist
Use: maintaining sedation on ITU, total IV anaesthesia and daycase surgery
Positives
Anti-emetic properties
Rapid induction
Rapidly metabolised
Negatives
Pain on injection
Hypotension – myocardial depression
Sodium Thiopentone
GABA agonist
Use: rapid sequence of induction
Positives - Very quick onset
Negatives - myocardial depression, laryngospasm, cant use as maintenance and no analgesic properties
Ketamine
NMDA antagonist
Use: induction of anaesthesia
Positives - useful in trauma/ haem instability as little myocardial depression, strong pain relief
Negatives - disorientation, hallucination, nightmares
Etomidate
GABA potentiator
Use: induction in hemodynamic stability
Positives - less hypotension caused
Negatives - primary adrenal suppression if prolonged (can’t use for maintenance), myoclonus, sig post-op vomiting, no analgesia
Fluranes
Isoflurane, desflurane, sevoflurane
Use: induction and maintenance of anesthesia
MOA - combination of GABA, glycine and NMDA
Negatives - myocardial depression, malignant hyperthermia, hepatotoxic (halothane)
NO
NMDA, nACh, 5-HT3, GABA and glycine receptors
Use: maintenance of anesthesia and analgesia (e.g. during labour)
Avoid in Pneumothorax
Tracheo-Oesophageal Fistula
RF - prolonged mechanical ventilation, traumatic intubation
= air leak and recurrent pneumonias secondary to aspiration
Methaemoglobinaemia
Hb that has been oxidised from fe2+ to fe3+, tissue hypoxia as Fe3+ cannot bind oxygen
Causes - (congenital) Hb variants, NADHm reductase deficiency, (acquired) sulphonamides, nitrates e.g., poppers, sodium nitroprusside, primaquine, aniline dye
= chocolate cyanosis, SOB, headache
Inv - normal pao2 but v sats
-> IV methylene blue, ascorbic acid if def
Curlings Ulcer
Peptic stress ulcer, acute gastric erosion linked to burns, ^children, ^duodenum
= bloody vomit, ^HR, v BP
Metformin and surgery
Day before - normal
Day of - only change if TDS, omit lunchtime dose
Sulfonylureas and surgery
Day before - normal
Morning op - omit OD dose or omit morning dose if BD
Afternoon op - omit all doses
GLP1, DPP4 and SGLT2
GLP1 (-tides) and DPP4 (-gliptins) - normal
SGLT2 (-flozins) - omit on the day
Once and Twice Daily Insulin
Once daily (Lantus, Levemir) - decrease by 20% on day before and day of
Twice daily (Novomix 30) - 50% morning of dose, rest normal
*If poorly controlled (Hba1c >69) then use VRII
Drugs to stop before surgery
Clopidogrel (^bleeding) - stop 7d before elective surgery
HRT (^VTE) - stop 4wks before
ACE inhibitors/ furosemide (exacerbate hypotension periop) - omit on the day
Betablockers confer protection against major adverse cardiac events and should be continued
Diabetes - target HbA1c <69, first on operating list
Anaphylaxis doses
<6 months = 100-150mcg
6 months - 6 years = 150mcg
6-12 = 300mcg
12yrs+ = 500mcg
Repeat every 5mins, IM anterolateral aspect of middle 1/3 of thigh (vastus lateralis)
Refractory: 2+ doses of adrenaline, give IV fluids and consider IV adrenaline infusion
Airway devices
Oropharyngeal
= easy to use, not well tolerated if awake
Nasopharyngeal
= good for v GCS or seizures, contra in basal skull fracture
Supraglottic
= used in low risk cases or if needed short time (arrest)
Laryngeal mask
= very easy, poor control against gastric reflux, used in day surgery
Only ET tube and tracheostomy protect from aspiration
Multiple facial injuries/ fractures ?cricothyroidotomy
ASA Grades
1 - Healthy, no smoking, no/ minimal alcohol
2 - Mild systemic disease e.g., current smoker, social drinker, pregnancy, BMI 30-40, well controlled DM/ HTN
3 - Severe systemic e.g., poor control, COPD, BMI > 40, ESRD with regular dialysis
4 - Severe and constant threat to life e.g., MI <3m
5 - Would die without surgery e.g., ruptured AAA
6 - Brain dead
Burns: Subtypes
Superficial epidermal (first degree) - red, painful
Partial thickness (second degree)
- Superficial dermal - pale pink, blistered, slow CR
- Deep dermal - white, v sensation
Full thickness (third degree) - white/ brown, painless
Management of Burns
-> A-E, consider early intubation, irrigate with cold water and layer with clingfilm, just water if chemical
Superficial epidermal -> analgesia, emollients
Superficial dermal -> leave blisters intact, no creams, review in 24hrs
Circumferential -> escharotomy
Fluids in Burns
Fluid resus if >15% TBSA in adults (>10% kids)
Parkland formula to calculate
% of surface area x kg x 4 = 24hr requirement
- 50% in first 8hrs, 50% in next 16hrs
Referral in burns
All deep dermal and full thickness
Superficial dermal if >3% TBSA in adults or 2% in kids, or if affects hands, face, feet, flexures or genitals
All circumferential, inhalation, electrical, chemical, NAI
Brainstem Death
- No light reflex (fixed pupils)
- No corneal reflex
- No oculo-vestibular reflex (caloric test; eye movement when ice water into ear)
- No cough or gagging reflex
- No observed respiratory effort
Deep tendon reflexes are intact (monosynaptic reflex not directly controlled by the brain)
Shockable and Unshockable
‘shockable’ rhythms: VF, pulseless VT
‘non-shockable’ rhythms: asystole, pulseless-electrical activity
GCS to I+V
GCS < 8 indicates the patient cannot protect their own airway
-> urgent intubation and ventilation
Trauma and Tachycardia
Location of traumatic haemorrhage
= the floor (external haemorrhage), chest, pelvis, long bones and abdomen (internal)
BP may be normal - exclude clinically significant bleeding before attributing tachycardia to pain alone
Beware beta blockers (no tachy response)
Pre-op bloods (elective)
Minor
No routine bloods (unless ASA 3/4 and indicated)
Intermediate
ASA2 consider U&E, ECG if indicated.
ASA3+ consider FBC, coag. Yes U&Es and ECG
Major
FBC in all
ASA2+ yes U&Es and ECG. consider coag ASA3
Muscle Relaxants
Depolarising NM blocker
Suxamethonium
MOA - inhibits action of acetylcholine at NMJ
**fastest onset, shortest duration
SE: generalised contraction prior to paralysis, ^K, malignant hyperthermia, v AChE, ^intra-ocular pressure, fasciculation
Non-Depolarising NM Blocker (neostigmine reverses)
Atracurium
**Duration of action 30-45mins
SE: general histamine release on administration may produce facial flushing, ^HR, v BP
Vecuronium
Degraded by liver and kidney
Pancuronium
**Onset in 2mins, duration <2hours
Post-Op Ileus
Paralytic ileus, post-bowel surgery
= distention, abdo pain, n+v, no flatus
-> NBM, IV fluids, correct electrolytes
ALS Adrenaline Doses
Anaphylaxis: 0.5mg so 0.5ml of 1:1,000 IM
Cardiac arrest: 1mg so 10ml of 1:10,000 IV or 1ml of 1:1000 IV
Quinine Toxicity
Use - antimalarial
SE: broad QRS, ^QT, ^PR, into VT/VF, v glucose, tinnitus, visual blurring, flushing, dry skin, abdominal pain, pulmonary oedema
