Anaesthesia Machine, Breathing Systems and Ventilators MCQs

Anaesthesia · 23 free questions with answers & explanations.

1. In a Mapleson D breathing system (Bain circuit) used for spontaneously breathing patients, which feature distinguishes it from the Mapleson A system?
2. An increase in inspired carbon dioxide (CO2 rebreathing) is detected on the capnograph waveform during general anaesthesia with a circle system. The MOST likely cause is:
3. In a Mapleson D breathing system (Bain circuit), the fresh gas flow required to prevent rebreathing during spontaneous ventilation is approximately:
4. The fail-safe mechanism on an anaesthesia machine is designed to prevent delivery of a hypoxic mixture. This device:
5. The Mapleson D breathing system (Bain circuit) is considered more efficient for controlled ventilation than spontaneous breathing. What minimum fresh gas flow (FGF) is required for controlled ventilation in an adult to prevent rebreathing?
6. Soda lime (carbon dioxide absorbent) reacts with certain volatile anaesthetics to produce toxic compounds. Specifically, sevoflurane reacts with desiccated soda lime to produce which toxic compound?
7. A pressure-volume loop displayed on modern anaesthesia workstations shows a rightward shift of the inspiratory limb with decreased peak pressure but unchanged tidal volume. This finding is most consistent with which condition?
8. The Mapleson D circuit (Bain coaxial modification) is commonly used for controlled ventilation. What is the minimum fresh gas flow (FGF) required to prevent rebreathing during IPPV in an adult?
9. The anaesthesia ventilator bellows do not ascend to the top of the bellows housing during the expiratory phase. Which of the following is the most likely cause?
10. Pressure support ventilation (PSV) mode on the ICU ventilator helps wean patients from mechanical ventilation. What is the minimum level of pressure support that overcomes endotracheal tube resistance during a spontaneous breathing trial?
11. The Mapleson A (Magill) system is considered the most efficient breathing system for spontaneous ventilation. The minimum fresh gas flow (FGF) required to prevent CO2 rebreathing during spontaneous ventilation with a Mapleson A system is:
12. Barotrauma during mechanical ventilation in theatre is MOST closely related to which ventilator parameter?
13. During a low-flow anaesthesia technique, the inspired CO2 concentration on the capnograph begins to show a steady baseline rise above zero. The MOST likely cause is:
14. During a low-flow anaesthetic at 0.5 L/min with sevoflurane, a nurse bumps the CO2 absorber canister and desiccated soda lime (not replaced for 4 days) is present. Which dangerous compound can form from the interaction of sevoflurane with desiccated soda lime?
15. The Mapleson classification of breathing systems is based on a functional principle. In which Mapleson system is CO2 rebreathing LEAST likely during controlled ventilation at moderate fresh gas flows?
16. During pressure-controlled ventilation on an anaesthesia machine, the compliance of the breathing system is 4 mL/cmH2O. At a set peak inspiratory pressure of 20 cmH2O above PEEP 5, what volume is 'lost' to circuit compression per breath?
17. A Mapleson D breathing system is used for spontaneous ventilation in a 70 kg adult. The fresh gas flow (FGF) required to prevent rebreathing during spontaneous ventilation is approximately:
18. Regarding low-flow anaesthesia (LFA) with FGF <1 L/min in a circle absorber system, which statement is MOST accurate about the risk of accumulation of potentially harmful gases?
19. During anaesthesia with a circle system, the CO₂ absorbent changes from white to violet. However, EtCO₂ remains normal. The MOST likely explanation is:
20. The Mapleson A (Magill) system is MOST efficient for which clinical scenario?
21. An anaesthetist notices a sudden increase in peak airway pressure from 18 to 38 cmH₂O with unchanged plateau pressure during volume-controlled ventilation. The MOST likely cause is:
22. The Mapleson A (Magill's) breathing system is MOST efficient for spontaneous ventilation. What is the minimum fresh gas flow (FGF) required for spontaneous ventilation to prevent rebreathing in Mapleson A?
23. The fail-safe valve (hypoxic guard/pressure sensor shut-off) on the anaesthesia machine is designed to prevent delivery of a hypoxic mixture. What is the key limitation of this device?