Altitude and Diving Physiology Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Altitude and Diving Physiology. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Altitude and Diving Physiology Indian Medical PG Question 1: Which of the following statements are correct regarding primary survey/management of traumatic head injury patient?
I. Ensure adequate oxygenation and circulation
II. Exclude hypoglycaemia
III. Check for mechanism of injury
IV. Check pupil size and response
Select the answer using the code given below :
- A. II, III and IV
- B. I, III and IV
- C. I, II and III
- D. I, II and IV (Correct Answer)
Altitude and Diving Physiology Explanation: ***I, II and IV***
- **Primary survey** in trauma management, including head injury, focuses on immediately life-threatening conditions (Airway, Breathing, Circulation, Disability, Exposure). Ensuring adequate **oxygenation and circulation** (Statement I) is paramount to prevent secondary brain injury.
- Exclude **hypoglycemia** (Statement II) is critical because altered mental status due to low blood sugar can mimic head injury and delay appropriate treatment, making it an essential part of the 'D' (disability) assessment. Checking **pupil size and response** (Statement IV) is also part of the 'D' assessment, providing vital information about potential brain stem compromise or intracranial pressure changes.
*II, III and IV*
- While excluding hypoglycemia and checking pupil response are crucial parts of the primary survey, Statement III, "Check for mechanism of injury," is typically part of the **secondary survey** or initial assessment but not immediately life-saving like ABCD.
- The primary survey prioritizes immediate threats to life, and while understanding the mechanism of injury informs subsequent care, it does not directly address a patient's immediate physiologic stability.
*I, III and IV*
- This option includes checking the mechanism of injury (Statement III) as part of the primary survey, which is generally conducted after the **life-threatening conditions** are addressed.
- It omits the critical step of excluding **hypoglycemia** (Statement II), which is an immediate reversible cause of altered mental status that must be ruled out during the primary assessment.
*I, II and III*
- This option correctly includes ensuring adequate **oxygenation and circulation** (Statement I) and excluding **hypoglycemia** (Statement II) as part of the primary survey.
- However, it incorrectly includes checking for the **mechanism of injury** (Statement III) as a primary survey component and omits checking **pupil size and response** (Statement IV), which is an essential part of the 'Disability' assessment in the primary survey for head injury.
Altitude and Diving Physiology Indian Medical PG Question 2: A 45-year-old woman presents with shortness of breath and cyanosis. Arterial blood gas shows a low oxygen saturation despite a normal PaO2. What is the most likely diagnosis?
- A. Pulmonary embolism
- B. Carbon monoxide poisoning (Correct Answer)
- C. Asthma
- D. Pneumonia
Altitude and Diving Physiology Explanation: ***Carbon monoxide poisoning***
- **Carbon monoxide** binds to **hemoglobin** with a much higher affinity than oxygen, forming **carboxyhemoglobin (COHb)**, which prevents oxygen transport [1].
- This leads to a low-oxygen saturation reading by pulse oximetry, even when the **partial pressure of oxygen (PaO2)** in the blood is normal, because the PaO2 measures dissolved oxygen, not oxygen bound to hemoglobin [1], [2].
- Furthermore, CO causes a leftward shift of the oxyhemoglobin dissociation curve affecting the offloading of oxygen from hemoglobin to the tissue [1], [2].
*Pulmonary embolism*
- A **pulmonary embolism** typically causes **hypoxemia** and a low **PaO2** due to ventilation-perfusion mismatch, which contradicts the normal PaO2 in this case.
- While it can cause shortness of breath and cyanosis, the **ABG** findings of **normal PaO2** despite **low oxygen saturation** are not characteristic.
*Asthma*
- **Asthma** involves **bronchoconstriction** and airflow obstruction, leading to **hypoxemia** and a **low PaO2** in severe cases.
- It would not typically present with a normal PaO2 alongside a significantly desaturated pulse oximeter reading, as the PaO2 directly reflects the amount of dissolved oxygen in the blood.
*Pneumonia*
- **Pneumonia** causes impaired gas exchange due to inflammation and fluid in the alveoli, resulting in **hypoxemia** and a **low PaO2**.
- The coexistence of **normal PaO2** with **low oxygen saturation** points away from pneumonia, as the primary issue in pneumonia is usually a failure to oxygenate the blood effectively, thus lowering PaO2.
Altitude and Diving Physiology Indian Medical PG Question 3: In an accident case, after the arrival of medical team, all should be done in early management except;
- A. Glasgow coma scale
- B. Check BP (Correct Answer)
- C. Stabilization of cervical vertebrae
- D. Check Respiration
Altitude and Diving Physiology Explanation: ***Check BP***
- In the **immediate/early management** of trauma (primary survey), while circulation assessment is crucial, the **initial assessment of circulation** focuses on:
- **Pulse rate and quality** (radial, carotid)
- **Capillary refill time**
- **Skin color and temperature**
- **Active hemorrhage control**
- **Formal blood pressure measurement** with a cuff, while important, is typically recorded during or after these rapid initial assessments, as it takes more time to obtain an accurate reading.
- In the context of this question, among the four options listed, BP measurement is relatively less immediate compared to the other life-saving priorities (airway protection, breathing assessment, C-spine stabilization, and GCS).
- **Note:** This is a nuanced distinction - BP is assessed during primary survey, but the other three options have more immediate life-threatening implications if not addressed.
*Glasgow coma scale*
- **GCS assessment** is part of the **"D" (Disability)** step in the ATLS primary survey.
- It is performed early to assess neurological status and level of consciousness.
- GCS <8 indicates need for **definitive airway protection** (intubation).
- This is a critical early assessment that guides immediate management decisions.
*Stabilization of cervical vertebrae*
- **C-spine immobilization** is part of the **"A" (Airway)** step - "Airway with cervical spine protection."
- It is performed **simultaneously** with airway assessment using a **rigid cervical collar**.
- This is the **first priority** in trauma management to prevent secondary spinal cord injury.
- All trauma patients should be assumed to have C-spine injury until proven otherwise.
*Check Respiration*
- **Respiratory assessment** is part of the **"B" (Breathing)** step in the ATLS primary survey.
- This involves checking:
- **Respiratory rate and pattern**
- **Chest wall movement**
- **Air entry bilaterally**
- **Signs of tension pneumothorax or flail chest**
- This is an immediate life-saving priority and must be assessed early.
Altitude and Diving Physiology Indian Medical PG Question 4: Compensating mechanism involved in acclimatization to altitude is:
- A. Respiratory depression
- B. Hypoventilation
- C. Hyperventilation (Correct Answer)
- D. Respiratory acidosis
Altitude and Diving Physiology Explanation: ***Hyperventilation***
- **Hyperventilation** is the primary immediate compensatory mechanism at altitude, increasing alveolar ventilation to improve **oxygen uptake** despite lower partial pressures of oxygen.
- This response is mediated by the **carotid bodies**, which sense the reduced arterial PO2 and stimulate the respiratory center.
*Respiratory depression*
- **Respiratory depression** would worsen hypoxia at high altitude by further reducing **oxygen intake**.
- This is not a compensatory, but rather a detrimental, response in this setting.
*Hypoventilation*
- **Hypoventilation** decreases the amount of air reaching the alveoli, exacerbating the **hypoxia** present at high altitudes.
- This would further reduce the **partial pressure of oxygen** in the blood, which is counterproductive for acclimatization.
*Respiratory acidosis*
- **Respiratory acidosis** results from **hypoventilation** and CO2 retention.
- Acclimatization leads to **respiratory alkalosis** due to increased CO2 excretion from hyperventilation, which is then partially compensated by renal mechanisms.
Altitude and Diving Physiology Indian Medical PG Question 5: Which drug is given to prevent acute mountain sickness?
- A. Acetazolamide (Correct Answer)
- B. Diltiazem
- C. Digoxin
- D. Dexamethasone
Altitude and Diving Physiology Explanation: ***Acetazolamide***
- This drug is a **carbonic anhydrase inhibitor** that acidifies the blood and causes compensatory hyperventilation, increasing oxygenation.
- It is the **first-line prophylactic agent** for acute mountain sickness (AMS) and is best started 24-48 hours before ascent.
- Most effective and widely recommended for AMS prevention.
*Digoxin*
- This is a **cardiac glycoside** used to treat heart failure and irregular heartbeats.
- Its mechanism of action is unrelated to the physiological changes that cause acute mountain sickness.
*Diltiazem*
- This is a **calcium channel blocker** primarily used for hypertension, angina, and certain arrhythmias.
- It has no known role in the prevention or treatment of acute mountain sickness.
*Dexamethasone*
- While **dexamethasone** can be used for AMS prophylaxis, it is typically reserved as an **alternative agent** when acetazolamide is contraindicated or not tolerated.
- It is more commonly used for **treatment** of severe altitude illness including **High Altitude Cerebral Edema (HACE)** and **High Altitude Pulmonary Edema (HAPE)**.
- **Acetazolamide remains the preferred first-line prophylactic agent** due to its mechanism of action that directly addresses the underlying pathophysiology of AMS.
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