Dr. Jhanvi Bajaj

DNB June 2026 Paper 1 Discussed By Dr. Jhanvi Bajaj: MAC Question| What Residents Should Revise 

by with No Comment Anesthesia

Estimated reading time: 6 minutes

The DNB June 2026 Paper 1 included several questions that were closely aligned with previously asked concepts. One of the recalled questions focused on Minimum Alveolar Concentration (MAC), its definite. 

Let’s break it down the way you would actually revise it before an exam. 

First things first: What exactly is MAC? 

Minimum Alveolar Concentration (MAC) is the minimum alveolar concentration of an inhalational anesthetic at 1 atmosphere pressure that prevents movement in response to a standard surgical incision in 50% of patients. 

That definition can look unnecessarily complicated when you first read it. 

The easiest way to understand it is: 

MAC tells you how much of a volatile anesthetic is needed to prevent movement during surgery in 50% of patients. 

And there is one relationship you should not forget: 

Lower MAC = Higher potency 

Higher MAC = Lower potency 

For example, the MAC of sevoflurane is around 2%, whereas desflurane has a MAC of around 6%. 

So, a lower concentration of sevoflurane is needed to achieve the same endpoint. 

That means: 

Sevoflurane is more potent than desflurane. 

This is why MAC is useful when comparing the potency of inhalational anesthetic agents. 

Important MAC values to revise 

You don’t need to turn this into a memory exercise where you keep staring at numbers for hours. Start by knowing the approximate values and, more importantly, their order. 

Inhalational agent Approximate MAC 
Methoxyflurane 0.16% 
Halothane 0.75% 
Isoflurane 1.4% 
Sevoflurane 2% 
Desflurane 6% 
Nitrous oxide 104% 

Methoxyflurane has a very low MAC, which means high potency. However, it is not commonly used because of its nephrotoxicity. 

For exams, knowing the commonly tested values is more useful than trying to memorise every possible number. 

Factors that decrease MAC 

Now comes the part that is often tested in MCQs and theory questions. 

Think about it this way: 

If the patient is already more sedated or more sensitive to anesthetic effects, you need less volatile anesthetic. 

So MAC goes down. 

Important factors include: 

  • Increasing age 
  • Hypothermia 
  • Hypoxia 
  • Pregnancy 
  • Opioids 
  • Benzodiazepines 
  • Alpha-2 agonists such as dexmedetomidine and clonidine 
  • Acute alcohol intoxication 

A simple revision line: 

Elderly + hypothermia + pregnancy + CNS depressants → ↓ MAC 

Pregnancy 

Pregnancy is a particularly important association. 

The requirement for inhalational anesthetic decreases during pregnancy. Increased progesterone levels are one of the factors associated with this increased sensitivity. 

So, for a quick recall: 

Pregnancy → ↓ MAC 

Acute alcohol vs chronic alcohol: Don’t mix them up 

This is one of those small differences that can easily cost you a mark. 

Acute alcohol intoxication → ↓ MAC 

The patient is already under the sedative effects of alcohol, so less anesthetic is required. 

Chronic alcohol use → ↑ MAC 

With chronic exposure, tolerance develops. The patient is therefore less sensitive to the sedative effects, and the anesthetic requirement increases. 

So remember: 

Acute alcohol = decrease 

Chronic alcohol = increase 

Factors that increase MAC 

Now flip the concept. 

If the patient is more stimulated, has increased metabolic activity, or has developed tolerance to a sedative substance, the anesthetic requirement can increase. 

Important factors include: 

  • Hyperthermia 
  • Hypernatremia 
  • Acute cocaine use 
  • Chronic alcohol use 
  • Chronic amphetamine use 
  • Infancy, particularly around 6 months of age 

Again, don’t just memorise the list. Try to understand the pattern. 

Age and MAC 

Age is an important one. 

MAC is relatively high in infancy and reaches its maximum around 6 months of age. 

After that, it gradually decreases with age. 

So: 

Infant → higher MAC 

Elderly → lower MAC 

This comparison is worth remembering because it can easily appear as an MCQ. 

What does not significantly affect MAC? 

Not every patient characteristic changes MAC. 

The commonly recalled points include: 

  • Gender 
  • Thyroid disease 
  • Duration of anesthesia 

These are useful to remember because they can be used as distractors in exam questions. 

What about the CNS effects? 

The recalled DNB question also asked about the effects of inhalational anesthetic agents on the CNS. 

Volatile anesthetics produce dose-dependent CNS depression. Their effects include changes in: 

  • Consciousness 
  • Memory 
  • Cerebral activity 
  • Immobility 

They can also alter cerebral blood flow and intracranial dynamics, which is why their CNS effects are clinically important rather than being just a theory topic. 

When preparing this part for theory, don’t learn it as a random list. Try to connect each effect with its clinical relevance. 

How should you write this answer in DNB theory? 

If you get a similar question in your exam, don’t start writing everything you remember about inhalational anesthetics. 

Keep the answer organised. 

A simple structure would be: 

1. Definition of MAC 

2. Relationship between MAC and potency 

3. Important MAC values 

4. Factors decreasing MAC 

5. Factors increasing MAC 

6. Factors with little or no effect on MAC 

7. CNS effects of inhalational anesthetics 

This makes your answer easier to follow and also reduces the chance of leaving out one part of a multi-component question. 

Five-minute revision before the exam 

If you are revising MAC at the last minute, ask yourself: 

Can I define MAC in one sentence? 

Can I explain why lower MAC means greater potency? 

Do I remember the approximate MAC of sevoflurane and desflurane? 

What happens to MAC in pregnancy? 

What happens in elderly patients? 

Can I differentiate acute and chronic alcohol use? 

Which drugs decrease MAC? 

Which conditions increase MAC? 

If you can answer these without looking at your notes, your basic MAC revision is in good shape. 

The bigger lesson from this DNB paper 

The important takeaway isn’t just MAC. 

The June 2026 Paper 1 recalls show why residents should not ignore previously asked and repeatedly tested concepts while preparing for DNB theory. 

A topic that looks simple can still become a full-length theory question when the examiner asks for its definition, clinical factors, numerical values and physiological effects together. 

So while revising, don’t just ask: 

“Have I read this topic?” 

Ask: 

“Can I write this topic as a structured answer if it comes in my paper tomorrow?” 

That small change in the way you revise can make your preparation much more exam-oriented. 

Note: This discussion is based on student recalls of the DNB June 2026 Paper 1. The exact question paper was not available at the time of the discussion. 
 
Watch Video: DNB JUNE 2026 – PAPER 1 | MAC Question Discussion | Dr. Jhanvi Bajaj 

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Dr. Jhanvi Bajaj

Regional Anesthesia PYQs: Important for NEET SS – Discussed by Dr. Jhanvi Bajaj

by with No Comment Anesthesia

Estimated reading time: 5 minutes

If you’re preparing for the regional anesthesia exam, most of you tend to ask what the best resources are. Dr Jhanvi Bajaj advises that the reference book of choice is Shemby’s Regional Anesthesia. It has both MCQs and theoretical answers to questions across nearly all subjects. The other useful resource is the Ganga Hospital Handbook of Regional Anesthesia, and you can generally obtain this as a PDF from past fellows. In combination, these are good to use to prepare for the exam.

Let’s go through some high-yield MCQs discussed in detail:

MCQ 1: Sudden Drop in Blood Pressure After Spinal Anesthesia
Scenario:

A 48-year-old man with well-controlled type 2 diabetes is scheduled for a total hip replacement. He receives 12 mg of hyperbaric bupivacaine. Seven minutes later, his blood pressure drops from 140/85 to 90/60 mmHg. He is alert, comfortable, and has no chest pain, palpitations, or shortness of breath.

Question: What is the most likely explanation for this acute hypotension?
Option Analysis:
  1. Acute myocardial ischemia: Typically presents with chest pain, palpitations, sweating, arrhythmias, or restlessness. None of these are noted, so it is unlikely.
  2. Systemic toxicity of local anesthetic (LAST): Features include peri-oral paresthesia, numbness, headache, tinnitus, metallic taste, seizures, or arrhythmias. None of these is described.
  3. Accidental intravascular injection: 2.5 mL of hyperbaric bupivacaine is insufficient to be toxic.
  4. Normal sequence of spinal anesthesia ✅
Why:

Spinal anesthesia suppresses nerve fibres in the sequence: autonomic → sensory → motor. Thoracolumbar spinal nerves’ sympathetic fibres are blocked initially. This results in vasodilation and leads to a precipitous fall in blood pressure.

Management:
  • Give IV fluids to restore intravascular volume.
  • If required, administer vasoconstrictors such as phenylephrine, ephedrine, or mephentermine.
MCQ 2: Caudal Block in a Child
Scenario:

A 4-year-old boy is to undergo circumcision using general anesthesia. For pain relief postoperatively, a caudal block is done. One feels a definite “pop” or give-way as the needle traverses the sacral hiatus.

Question: What ligament causes this sensation?
Discussion:
  • Caudal anesthesia is essentially an epidural block, but is done via the sacral hiatus.
  • Usually reserved for children younger than 8, since the sacral cornu ossifies and closes the hiatus after this age.
Landmarks for Caudal Block:
  • Palpate the posterior superior iliac spines (PSIS).
  • Concept an equilateral triangle below the PSIS – the sacral hiatus is the central depression.
  • The sacral cornua are palpable on either side.
Needle Pathway:
  1. Skin
  2. Subcutaneous tissue
  3. Sacrococcygeal ligament ✅ – this is the “pop” felt.

After piercing the ligament, the needle enters the caudal space, and local anesthetic is administered.

Tip: The sensation of “pop” is the feeling of crossing the sacrococcygeal ligament and entering the caudal epidural space.

MCQ 3: Femoral Nerve Block Anatomy
Scenario:

A 62-year-old woman with advanced knee osteoarthritis undergoes elective total knee arthroplasty. Post-op analgesia will be achieved with a USG-guided femoral nerve block by the anesthetist.

Question: Where is the femoral nerve in relation to the femoral artery?
Discussion:

Femoral nerve blocks are less frequent for TKA since they cause weakening of the quadriceps, complicating early mobilization. Adductor canal block or local infiltration is used by surgeons for analgesia while maintaining the patient mobile.

Anatomy:
  • Two fasciae enclose the nerve: fascia lata superiorly and fascia iliaca, which come into contact with the nerve.
  • The femoral nerve is lateral and posterior to the femoral artery.
  • Remember VAN: Vein → Artery → Nerve, medial to lateral.
  • The Sartorius muscle courses from lateral to medial, assisting in localising the nerve.

Technique: Use an in-plane approach, following the nerve from the knee to the inguinal crease before branching.

✅ Answer: Lateral to the femoral artery

MCQ 4: Pudendal Nerve Block
Scenario:

A 38-year-old man with perineal and genital pain (pudendal neuralgia) needs a USG-guided pudendal nerve block.

Question: If the drug diffuses too laterally past the internal pudendal artery, what nerve might be blocked as well?
Discussion:
  • The pudendal nerve arises from S2–S4 and supplies the perineum, external genitalia, and anal region.
  • It passes from the greater sciatic foramen, between sacrospinous and sacrotuberous ligaments, and re-enters the pelvis via the lesser sciatic foramen, lying near the internal pudendal artery and vein.
  • Lateral spread of the drug beyond the artery may block the sciatic nerve.

✅ Answer: Sciatic nerve

MCQ 5: Nerve Blocks for Complete Foot Anesthesia
Scenario:

A 45-year-old man with chronic gout is undergoing surgery on the foot. The anesthetist desires a USG-guided ankle block for the whole foot.

Question: What nerves require blocking for complete anesthesia?
Discussion:

Dorsal surface:

  • Superficial peroneal nerve – the greater part of the dorsal foot
  • Deep peroneal nerve – first web space
  • Sural nerve – lateral half
Plantar surface:
  • Saphenous nerve – medial foot
  • Tibial nerve (TBL) → medial & lateral plantar branches
  • Sural nerve – lateral foot

✅ Answer: Superficial peroneal, deep peroneal, tibial (medial & lateral plantar), saphenous, and sural nerves

Conclusion:

Dr. Jhanvi Bajaj’s discussion emphasises how anatomy, nerve physiology, and clinical reasoning must be mastered in order to excel on regional anesthesia exams. These MCQs are just a small subset of what you must learn for success with both exams and patient care.

For access to more high-yield questions, detailed explanations, and focused preparation for SS, NEET, and fellowship exams, subscribe to Conceptual Anesthesia. You’ll get carefully curated MCQs, step-by-step discussions, and expert guidance to boost your preparation.

Subscribe to Conceptual Anesthesia today and take your regional anaesthesia skills to the next level!
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