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Table of contents:
- Preparation for surgery: Pre-op fluid management; IV access; Local anesthetic agents; Anesthesia; Airway management; Muscle relaxant and Malignant hyperthermia; Acute dystonic reaction
- Blood products - cross matching
- Circulatory support; Hypovolemia
- Nutrition; Refeeding syndrome; Feeding
- Post-op: Fluids; POCD; PE; Thrombo-prophylaxis; Atropine
- Surgical complications
- Gases for laparoscopy
- Sterilization
- Sutures; Wound closure; Bleeding management; Tissue reconstruction
- Surgical drains; Diathermy; Electrosurgery
- Skin lesions
- Nutrition options in surgical pts
High-yield / Revision Questions:
Tricky Q’s: 🌟
What is the expected abnormality in a pt given several liters of 0.9% normal saline?
- Hyperchloremic metabolic acidosis
Pt on warfarin requires immediate surgery. What should be given initially?
- Prothrombin complex
Note that Vitamin K is not given, since it takes time to take effect.
What is the ideal target INR for pt taking warfarin for superficial femoral thrombosis?
- Ideal INR = 2-3
What is the long-term mx of pt w/ post phlebitis syndrome (thrombophlebitic syndrome)? - Compression stockings and analgesics; Low dose heparin; Leg elevation; Warm compress
- Ans: Compression stockings and analgesics
Q: 7 days post-laparotomy, the pt becomes confused. Serosanguinous discharge is observed seeping out of the wound. Most likely explanation? - Anastomotic leak; Abscess collection; Wound dehiscence; Infection; Hematoma
- Ans: Wound dehiscence
- Answer is NOT anastomotic leak, as it will happen much earlier when pt is eating by then; also if hypoalbuminemia, will be more likely to leak as a result of edema 🌠
Q: POD 7 pt w/ anterior resection and colonic anastomosis develops abdominal pain, pyrexia, tachycardia and hypotension. Likely cause? - Septic shock; Ruptured abdominal aneurysm; Cardiogenic shock; Intra-abdominal hypertension
- Ans: Septic shock
Note on postoperative fever / pyrexia 🌠
Q’s re: Pharmacology: 🌟
Q: A pt was sedated with midazolam, however, she became hypoxic. What is the most appropriate agent to reverse this?
- Flumazenil - a benzodiazepine antagonist (inhibits by competition at GABA binding sites)
- Interestingly, benzodiazepine is an antidote to cocaine overdose 🌠
Q: Which of the following can be administered via peripheral route in a non-cardiac arrest setting? - Milrinone; Noradrenaline; Adrenaline; Metaraminol; Dobutamine
- Ans: Metaraminol - an alpha1 receptor agonist (causing peripheral vasoconstriction and thus, high BP)
- Note that inotropes and vasopressors can only be administered via a central vein!
- Metaraminol is an exception.
Q: Neostigmine is administered to a pt who received a non-depolarizing muscle relaxant. It is most likely to result in? - Prolonged muscle relaxation; Tachycardia; Hypertension; Bradycardia; Decreased gut peristalsis
- Bradycardia - hence, atropine is administered to counter this effect (atropine is an anti-muscarinic, blocks receptors from ACh, hence, increases HR)
Q’s re: parenteral feeding & nutrition: 🌟
Q: Which of the following does not need monitoring during home parenteral nutritional support? - Folate levels; Zinc levels; Vitamin D; Thyroid function; Bone densitometry
- Ans: Thyroid function
Q: Which is not typically included in total parenteral nutrition solutions? - Fiber, lipid, potassium, glucose, magnesium
- Ans: Fiber
- Note that TPN = delivered into venous system (should not have fiber in it).
[more high-yield Q’s and tips in our notes]
American Society of Anesthesiologists physical status scoring (ASA)🌟
→ a metric to determine if someone is healthy enough to tolerate surgery and anesthesia
Table of ASA classification and their respective examples: 🌠
- For the following cases, what are their ASA grades? 🌟
- ASA Grade 4 (severe systemic disease that is a constant threat to life)
- ASA Grade 1
- ASA Grade 3
- ASA Grade 5 (moribund patient - aka. at the brink of death - who will not survive without surgery)
- ASA Grade 2
A patient with a recent history of MI / TIA / CVS or has a cardiac stent
A patient with blood tests wnl presents with a lipoma on his back.
A patient with uncontrolled DM / HTN / asthma
A patient with a ruptured abdominal aneurysm
A patient with well-controlled DM / HTN / asthma
Preparation for Surgery
→ a metric to determine if someone is healthy enough to tolerate surgery and anesthesia
Elective cases:
- Consider preadmission to clinic to address medical issues
- Blood tests: FBC, U&E’s, LFT, Clotting profile, Group & Save
- Urine analysis +/- Pregnancy test
- Sickle cell test
- ECG +/- CXR
- Plan for thromboprophylaxis
Note that Further tests are performed depending on the type of surgical procedure and pt’s fitness level.
Emergency cases: 🌟
- (#1) Stabilize when needed (ABCDE protocol)
- (#2) Consider the need for antibiotics and route of administration
- (#3) Inform blood bank for major procedures and where patient has coagulopathy
- Obtain consent (watch out for DNR) and inform relatives
What specific preparations are required for the following? 🌟
Thyroid surgery - check:
- vocal cords
Parathyroid surgery - consider applying:
- Methylene blue (to identify gland)
Sentinel node biopsy - consider applying:
- Radioactive marker or patent blue dye
Surgery involving the thoracic duct - administer:
- Cream (to visualize thoracic duct)
Toggle for images:
Pheochromocytoma surgery - need to give patient: 🌟
- Alpha and beta blockers
Surgery for carcinoid tumors - need covering with: 🌟
- Octreotide
- A synthetic somatostatin that inhibits the release of serotonin and other bioactive agents by carcinoid tumors → this prevents carcinoid crisis (as carcinoid tumor releases a lot of serotonin, especially when triggered by biopsy, surgery or anesthesia)
[more high-yield details in our notes]
Local anesthetic agents 🌟
→ All local anesthetics have a chemical bond linking an amine to either an amide or ester
Most local anesthetics are of animo-amide types, which have ~(characteristics): 🌟
which have more favorable side effect profile and more stable in solution - the (2) exceptions are:
- Procaine and Benzocaine = have amino-ester groups - hence, are NOT amino-amide types
Lidocaine - mechanism of action:
- Affects Na channels in the axon
It can be given in combination with ~(substance) to limit systemic absorption?
- Adrenaline - its vasoconstrictive properties prevent absorption into blood vessels too quickly
- Note that adrenaline should NOT be given peripherally (i.e., at base of finger - aka. ring anesthesia) - as it may result in gangrene 💀
Bupivacaine:
Suitable for ~(type of wound) due to having longer duration of action than lignocaine
- Topical wound infiltration → given at the end of surgical procedures for longer duration of analgesic effect
Adverse effect: 🌟
- Cardiotoxic - hence it is contraindicated in region blockage Biers block (in case tourniquet fails) → use prilocaine instead
Prilocaine - it is the agent of choice for ~(type of anesthesia):
- Intravenous regional anesthesia e.g., Biers Block
- Injection of local anesthetic via IV of an upper or lower extremity that has been exsanguinated by compression or gravity, and has been isolated by means of a tourniquet from central circulation.
Toggle for details re: Bier’s block: 💡
What are the doses of local anesthetics with and without adrenaline? 🌟
Lignocaine - doses:
On its own:
- 3mg/kg
with adrenaline:
- 7mg/kg
Bupivacaine - doses:
On its own:
- 2mg/kg
with adrenaline:
- 2mg/kg
Prilocaine - doses:
On its own:
- 6mg/kg
with adrenaline:
- 9mg/kg
What are the 3 steps in managing local anesthesia toxicity? 🌟
- Stop the injection
- High flow 100% O2 via face mask + Cardiovascular monitoring
Administer lipid emulsion (Intralipid 20%)🌟 In case of toxicity with prilocaine → ~(solution) is given instead:
- Methylene blue
- Prilocaine is a known cause of methemoglobinemia, which is characterized by cyanosis and dyspnea. This occurs due to changes of hemoglobin to ferric states rather than being in ferrous state (Fe2+). This change causes the oxygen dissociation curve to shift to the left, resulting in tissue hypoxia. Methylene blue helps to revert the hemoglobin to its ferrous state, effectively reversing this effect.
Toggle for table summary:
[more high-yield details in our notes]
Adult respiratory distress syndrome
→ defined as acute condition w/ bilateral pulmonary infiltrates + severe hypoxemia (PaO2/FiO2 ratio<200) / dyspnea in the absence of cardiogenic pulmonary edema (either clinically or PCWP<18mmHg)
→ leads to decreased diffusion
Causes of ARDS? (5) 🌟
Essentially by any types of stress:
- Sepsis
- Direct lung trauma/injury
- Acute pancreatitis🌟(commonly asked) - it is known to precipitate ARDS
- Long bone fractures or multiple fractures → via fat embolism
- Head injury → triggers sympathetic system → acute pulmonary hypertension
Clinical features:
- Acute dyspnea and hypoxemia hours to days after the event / stressor
- Multi-organ failure
- Rising ventilatory pressures
Management: 🌠
- Tx underlying cause
- Antibiotics - if any signs of sepsis
- Diuretics - to achieve negative fluid balance
- Alveolar recruitment maneuvers such as: Prone ventilation, the use of PEEP, etc.
- Use of low tidal volumes for mechanical ventilation, as conventional tidal volumes may result in lung injuries
Q: Which of the following is NOT a feature of ARDS? 🌟 - It usually consists of type I respiratory failure; Patients typically require high ventilatory pressures; A Swann Ganz Catheter would typically have a reading in higher than 18mmHg; It may complicate acute pancreatitis; It may heal with fibrosis.
- Ans: Swan-Ganz catheter would typically have a reading of excess 18mmHg
- Under normal circumstances, Right heart pressure should be normal or higher 🌠
- Normal pulmonary artery systolic pressure at rest is 18-25 mmHg, with a mean pulmonary pressure ranging from 12-16 mmHg.
- PAOP is low in ARDS mainly due to severe inflammation causing vasodilatation.
In ARDS, the PAOP is low
Toggle for Berlin’s criteria, which is used to dx ARDS: 📖
[more high-yield details in our notes]
Management of pain
WHO analgesic ladder: 🌟
Initially begin with: (2)
- NSAIDs or paracetamol
If pain is not achieved, consider:
- Weak opioid - i.e., Codeine, or together with detropropoxyphene to minimize side effects
Finally, use:
- Strong opioid - i.e., morphine
Toggle for pain ladder:
Which anesthesia is most appropriate for the following conditions? 🌟
Open abdominal procedures
- Epidural anesthesia
Laparoscopic abdominal procedures
- Transversus abdominal plane block (TAP)
A term neonate who is recovering from an inguinal herniotomy
- Paracetamol - effective analgesic in children; besides, pain following herniotomy is relatively minor
An elderly man who underwent an appendicectomy via a lower midline laparotomy. What is the most suitable analgesia post-op?
- Patient controlled analgesic infusion (PAC)
Different classes of analgesics:
Neuropathic pain management based on NICE guidelines: 🌟
1st line
- Amitriptyline - may cause orthostatic hypotension
2nd line (2)
- Amitriptyline + pregabalin
3rd line (2)
- Give tramadol & refer to pain specialist (Avoid morphine!)
Trigeminal neuralgia is managed w/?
- Carbamazepine
Diabetic neuropathy is managed w/?
- Duloxetine
[more high-yield details in our notes]