Face Masks and Oxygen Delivery Devices Flashcards
Which of the following complications could be caused by an ill-fitting mask?
A. Injury to the branches of the facial or trigeminal nerves
B. Decreased apparatus dead space
C. Loss of air-tight seal over the face
D. Trauma to the eyes
E. Increased FiO2 delivered to patient
A, C & D
A. True. Excessive pressure can cause injury to the branches of the facial or trigeminal nerves.
B. False. An ill-fitting mask can increase the apparatus dead space. This is of particular importance in paediatric anaesthesia.
C. True. For edentulous patients or those with a naso-gastric tube, it can prove difficult to maintain an air-tight seal over the face if the mask is ill-fitting.
D. True. Imprecise application of the mask on the face can cause trauma to the eyes.
E. False. It is very difficult to predict the FiO2 in an ill-fitting face mask as it depends on the proportion of ambient air entrainment.
True or false:
Rebreathing of CO2 is of little clinical significance for all patients
False. The rebreathing of CO2 from the body of the mask is usually of little clinical significance in adults but may be a problem in some patients, especially children.
True or false:
Children usually compensate for rebreathing of CO2 by increased alveolar ventilation
False. Children are unable to compensate by increasing their alveolar ventilation.
True or false:
CO2 elimination can be improved by increasing the flow of fresh oxygen
True
True or false:
CO2 rebreathing increases when the mask body is large in relation to the patient’s face
True
True or false:
CO2 rebreathing decreases when the resist
False. The opposite is true: CO2 rebreathing increases in a well-fitting mask when the resistance to flow from the side holes is high.
The following statements apply to Venturi oxygen face masks.
The side holes on the mask are used to entrain ambient air
False. The side holes are used to expel exhaled gases. Ambient air is entrained via the Venturi device itself.
The following statements apply to Venturi oxygen face masks.
The narrower the Venturi constriction, the higher the FiO2 achieved
False. The narrower the constriction is, the lower the pressure. Thus, the more entrainment of ambient air, the lower the FiO2.
The following statements apply to Venturi oxygen face masks.
There is no rebreathing
True
The following statements apply to Venturi oxygen face masks.
They can be used in adult patients only
False. Venturi devices can be used for both adult and paediatric patients.
The following statements apply to Venturi oxygen face masks.
They are useful in patients who are dependent on the hypoxic drive
True
The following statements relate to oxygen delivery devices.
In an MC mask, the higher the inspiratory flow rate, the lower the FiO2
True
The following statements relate to oxygen delivery devices.
In a Venturi device, kinetic energy is related to pressure
False. Kinetic energy is related to velocity, whereas potential energy is related to pressure
The following statements relate to oxygen delivery devices.
Omitting the one-way valve in an MC mask with a reservoir bag, has no effect on its performance
False. The one-way valve improves the performance by preventing rebreathing.
The following statements relate to oxygen delivery devices.
A reservoir bag is usually added to a Venturi mask to improve its performance
False. There is no need to add a reservoir bag to the Ventui mask. The Venturi mask can cope with any inspiratory flow rate generated by the patient.
