Quiz 114 · Pulmonary Function Tests

Answers to Quiz 113 · Artificial Ventilation and Cardiopulmonary Resuscitation

1. What is the main drawback of positive-pressure artificial ventilation?

   Answer: It impairs venous return

   Your book's stated drawback is impaired venous return. The method is in fact the routine one in operating theatres, and it can deliver air or an air–O₂ mixture. Revise artificial respiration

2. In Drinker's iron-lung method, inspiration occurs when:

   Answer: The chamber pressure is lowered below atmospheric

   With the head and neck outside the airtight chamber, lowering the pressure around the body lets the chest expand and draw air in. Raising the chamber pressure compresses the chest and gives expiration. Revise artificial respiration

3. In the Holger Nielsen (back pressure–arm lift) method, which step produces inspiration?

   Answer: Raising the prone patient's arms until resistance is felt

   Lifting the arms expands the thorax, so the pressure inside it falls and air flows in. The back pressure that follows gives expiration. Revise artificial respiration

4. Which method of rescue breathing is preferred for infants and young children?

   Answer: Mouth-to-nose breathing

   Mouth-to-mouth is the method for adults, and mouth-to-nose is preferred in infants and children. Holger Nielsen is kept mainly for respiratory causes such as drowning. Revise artificial respiration

5. At what rate is mouth-to-mouth breathing kept up?

   Answer: 10–15 per minute

   Mouth-to-mouth runs at 10–15 breaths a minute. 10–12 a minute is the Holger Nielsen cycle rate, and 80–100 is your book's chest-compression rate. Revise artificial respiration

6. Artificial respiration on its own can save a patient only if:

   Answer: The heart and circulation are still working

   Ventilating the lungs helps only while the heart and circulation can carry the O₂ onward. If the heart has stopped too, full CPR is needed. Revise artificial respiration

7. Which two mechanisms account for most cardiac arrests?

   Answer: Asystole and ventricular fibrillation

   The heart stops pumping either because it is at a standstill (asystole) or because the ventricles fibrillate and make no effective contractions. Revise cardiopulmonary resuscitation (cpr)

8. During basic life support, how long does your book advise feeling for the carotid pulse?

   Answer: At least 10 seconds

   At least 10 s, so that a slow, irregular or very faint pulse is not missed. Current guidelines instead cap the check at 10 s, so compressions are not delayed. Revise cardiopulmonary resuscitation (cpr)

9. Which set matches your book's technique of external cardiac massage?

   Answer: 4–5 cm deep, 80–100 per minute, ratio 5:1

   Your book presses the sternum 4–5 cm at 80–100 a minute, with 5 compressions to each breath. Current guidelines use 5–6 cm, 100–120 a minute and 30:2. Revise cardiopulmonary resuscitation (cpr)

10. In cardiac arrest due to ventricular fibrillation, what is the major determinant of survival?

    Answer: The time from arrest to successful defibrillation

    A fibrillating heart pumps no blood, so survival depends above all on how soon a shock restores an effective rhythm. That is why defibrillation is started as early as possible. Revise cardiopulmonary resuscitation (cpr)

11. After a long resuscitation, a patient stays deeply unconscious, with no breathing, no reflex responses and no pupillary reaction to light. What do these signs suggest?

    Answer: Cerebral death; further resuscitation is futile

    Persistent deep coma with no breathing, no reflex responses and no pupillary light reaction points to cerebral death, when resuscitation stops being productive. Revise cardiopulmonary resuscitation (cpr)

12. Why is induced hypothermia used after a prolonged cardiac arrest?

    Answer: To lower metabolic demand and cerebral edema

    A long arrest causes hypoxic encephalopathy and cerebral edema. Cooling cuts the brain's metabolic demand and reduces the edema. Revise cardiopulmonary resuscitation (cpr)

13. What does the head tilt–chin lift maneuver achieve?

    Answer: It lifts the tongue clear and opens the airway

    Tilting the head back while supporting the chin extends the neck and raises the tongue away from the back of the throat. A stuck foreign body needs the Heimlich maneuver instead. Revise cardiopulmonary resuscitation (cpr)

14. In CPR, atropine sulphate 0.5 mg IV every 5 minutes is given mainly for:

    Answer: Bradycardia

    Your book gives atropine for bradycardia, and says it may help in asystole. Sodium bicarbonate (1 mEq/kg) is the one for hyperkalemia or acidosis, and VF needs defibrillation. Revise cardiopulmonary resuscitation (cpr)

15 questions on chapter 114. Pick one answer for each, then save. Your answers stay in this browser, and the right ones are shown at the top of the next quiz.

1. Which of these CANNOT be measured by a spirometer?

Functional residual capacityExpiratory reserve volumeInspiratory reserve volumeTidal volume

2. Inspiratory capacity is made up of:

IRV + TV + ERVIRV + TVERV + RVTV + ERV

3. In a normal adult, how much of the FVC is blown out in the first second?

65 to 75%95 to 97%50 to 60%80 to 85%

4. Lung compliance is defined as:

Maximum flow reached in the middle third of expirationFrictional resistance to airflow in the conducting airwaysChange in volume per unit change in transpulmonary pressureChange in transpulmonary pressure per unit change in volume

5. The normal peak expiratory flow rate in an adult is about:

40 to 60 L/min1000 to 1200 L/min150 to 250 L/min400 to 600 L/min

6. Which test assesses the strength of the inspiratory muscles?

Maximum mid-expiratory flow rateClosing volumeMaximal inspiratory pressurePeak expiratory flow rate

7. In obstructive lung disease, which of these is increased?

FEV₁/FVC ratioMaximum mid-expiratory flow rateRV/TLC ratioVital capacity

8. Which set of findings is typical of restrictive lung disease?

Reduced FVC with an FEV₁/FVC of 0.45Raised TLC with a reduced MMFRReduced FVC with a normal or supernormal FEV₁/FVCNormal FVC with a raised residual volume

9. A patient with weak inspiratory muscles and otherwise normal lungs would show:

Reduced TLC with a markedly raised RVNormal TLC with an FEV₁/FVC of 0.50Raised TLC with a raised RV/TLC ratioReduced TLC with an unchanged RV and preserved flow rates

10. Which of these decreases static lung compliance?

Bronchial asthmaChronic bronchitisPulmonary edemaEmphysema

11. A young man with episodic wheeze has a reduced FVC, an FEV₁/FVC of 0.50, a raised residual volume and a normal TLC. The pattern is:

Restrictive extraparenchymalRestrictive parenchymalObstructiveNormal for his age and height

12. The normal ratio of ventilation to perfusion in the lung is:

1.00.81.20.5

13. Which cause of hypoxemia leaves the alveolar–arterial O₂ gradient NORMAL?

Generalized hypoventilationRegional hypoventilationRight-to-left shuntDiffusion block

14. Breathing 100% oxygen fails to correct the low arterial PO₂ in:

Regional hypoventilationInterstitial pulmonary edemaA right-to-left shuntGeneralized hypoventilation

15. Expired air for gas analysis is collected using a:

Van Slyke apparatusHaldane–Priestley tubeSwan–Ganz catheterDouglas bag

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