Why we mixed in lignocaine n adrenaline while giving local anesthesia
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Why Adrenaline (Epinephrine) is Mixed with Lignocaine in Local Anaesthesia
Lignocaine (lidocaine) alone works well as a local anaesthetic, but adding adrenaline gives several important practical benefits:
1. Prolongs Duration of Action
Adrenaline is a vasoconstrictor. When injected alongside lignocaine, it constricts the local blood vessels, which:
- Slows the absorption of lignocaine into the systemic circulation
- Keeps the drug concentrated at the injection site for longer
- Significantly extends the duration of anaesthesia
2. Allows a Higher Safe Dose (Raises the Toxic Dose Ceiling)
This is one of the most clinically important reasons. Because adrenaline slows systemic absorption:
- Lignocaine without adrenaline: maximum dose is 3 mg/kg
- Lignocaine with adrenaline: maximum dose rises to 7 mg/kg
This allows the surgeon to use more anaesthetic solution safely for larger or more complex procedures. (Bailey and Love's Short Practice of Surgery, 28th Edition, p. 330)
Similarly, Prilocaine goes from 6 mg/kg to 9 mg/kg with adrenaline.
3. Hastens Onset
Vasoconstriction helps the local concentration of lignocaine remain higher and more available to nerve tissue, which speeds up the onset of the nerve block. (Bailey and Love's, p. 330)
4. Reduces Bleeding at the Operative Site
Vasoconstriction from adrenaline reduces local blood flow, which directly decreases bleeding. This gives better visualization during surgery and is especially useful for:
- Perianal and anorectal procedures
- ENT and nasal surgery
- Dental and oral procedures
- Skin and soft tissue surgery
Pye's Surgical Handicraft notes: "Bleeding is reduced if lignocaine containing adrenaline (1:200,000) is used." (Pye's Surgical Handicraft, 22nd Ed)
5. Reduces Systemic Toxicity Risk
By keeping lignocaine local and reducing the rate of systemic uptake, adrenaline lowers the risk of:
- Cardiovascular toxicity (arrhythmias, cardiac arrest)
- CNS toxicity (convulsions, loss of consciousness)
Standard Concentration Used
Adrenaline is typically added at a concentration of 1:200,000 (5 micrograms/mL). This is enough for vasoconstriction without causing significant systemic adrenergic effects.
When NOT to Use Adrenaline with Lignocaine
Despite its benefits, adrenaline is contraindicated in certain situations:
| Contraindication | Reason |
|---|---|
| End-arterial locations (fingers, toes, nose, ear, penis) | Vasoconstriction can cause ischaemia and tissue necrosis |
| Cardiovascular disease | Risk of cardiac arrhythmia, hypertension |
| Patients on tricyclic antidepressants (TCAs) or MAO inhibitors | Risk of severe hypertensive crisis or arrhythmia |
| Thyrotoxicosis | Exaggerated adrenergic response |
(Bailey and Love's Short Practice of Surgery, 28th Edition, p. 330)
Summary
| Benefit of Adding Adrenaline | Mechanism |
|---|---|
| Longer duration of anaesthesia | Slows local absorption via vasoconstriction |
| Higher permitted dose of lignocaine (up to 7 mg/kg) | Reduced systemic uptake |
| Faster onset | Higher local drug concentration maintained |
| Less bleeding | Direct vasoconstriction of local vessels |
| Reduced systemic toxicity | Drug stays local, slower entry into bloodstream |
In short, adrenaline acts as a "biological tourniquet" at the injection site - keeping the lignocaine where you need it, for longer, at a safer dose.
Where do I get tribhuvan university mbbs past question
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Tribhuvan University IOM MBBS past questions download
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TU IOM MBBS past questions Nepal free download PDF site
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IOM TU MBBS board exam past questions Nepal site:iom.edu.np OR site:nepalmedicalcouncil.org OR medicostuff.com OR merospark.com
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tribhuvan university MBBS past year questions "iom.edu.np" OR "medicostuff" OR "nepalmedicalstudent"
Here are the best places to find TU IOM MBBS past questions (both entrance exam and board/university exam questions):
Official Source
IOM Official Website - Examination Section
The IOM official website (iom.edu.np) has an Examination Control Division section. You can check:
- iom.edu.np → "Examination" or "Exam Section" for results, notices, and some past paper links
- Their archive section at iom.edu.np/archieve has old notices and some documents
However, IOM does not always post past question papers directly on their site - this is a common frustration for students.
Best Websites for TU IOM MBBS Past Questions
| Source | What You'll Find |
|---|---|
| Studocu.com | TU MBBS 1st year subject-wise question banks (Anatomy, Physiology, etc.) - free to view |
| Scribd.com | Search "IOM MBBS past questions" - many students upload PDFs here |
| SlideShare.net | IOM entrance past questions with answers (e.g., 2068 BS) |
| Gyanmark.com | Nepal-based site with CEE/IOM entrance MCQs and old questions |
YouTube Channels
Search these on YouTube - creators share PDF links in their video descriptions:
- Search: "IOM MBBS past questions PDF Nepal"
- The video by Ram Mandal MOE covers past year PDFs for IOM, BPKIHS, KU, and CEE
Facebook Groups & Communities
Some of the most active collections are shared inside Nepali medical student Facebook groups:
- Medical Story Nepal (Facebook page) - shares board exam question leaks and past papers
- Search Facebook: "TU IOM MBBS past questions" and join active groups
Subject-Specific Tips
| Year | Where to Look |
|---|---|
| 1st year (Anatomy, Physiology, Biochemistry) | Studocu, Scribd - very well covered |
| 2nd year (Pathology, Pharmacology, Microbiology) | Scribd, Facebook groups |
| Entrance exam (CEE/IOM) | Gyanmark, SlideShare, YouTube PDF links |
| 3rd/4th year & finals | Mostly in Facebook groups and Telegram channels |
Telegram
Search Telegram for: "TU IOM MBBS questions" or "Nepal MBBS past papers" - there are several active channels where students share past exam PDFs, especially before exams.
Bottom line: The most complete and up-to-date collections are usually on Studocu, Scribd, and Nepali medical student Telegram/Facebook groups rather than the official IOM website. If you are looking for entrance exam questions specifically, Gyanmark and YouTube PDF links are your best bet.
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