Oxygen Therapy And Ventilation Flashcards
What is the max amount of o2 used in a nasal cannula?
4L/min
What are the approx FiO2s for each litre of o2 given through a nasal cannula? (4)
• 1L / min – 24%
• 2L/ min – 28%
• 3L/ min – 32%
• 4L / min – 36%
Why should patient keep mouth closed when using a nasal cannula?
Positive end expiratory pressure is used with nasal cannulas
If mouth open then the effect this has is reduced
What are the 6 colours of Venturi mask? What are the FiO2 they give and what are the litres?
Blue = 24%, 2l
White = 28%, 4L
Orange = 31%, 6l
Yellow = 35%, 8l
Red = 40%, 10L
Green = 60%, 15l
What amount of o2 can be given through a simple (Hudson) face mask?
5-10L
What amount of o2 is given through a non-rebreather mask?
15L
What is the mechanism of a non-rebreather mask?
A one-way valve prevents exhaled air from entering the reservoir bag (the exhaled air exits via vents on the sides of the mask)
What is positive airway pressure?
Positive airway pressure = the pressure outside the lungs being greater than the pressure inside of the lungs. This results in air being forced into the lungs (down the pressure gradient), requiring less respiratory effort (offloading respiratory muscles to reduce the work of breathing).
When is CPAP used in a chronic setting? In an acute setting?
Chronic = OSA
Acute = T1RF
What is the mechanism of CPAP?
Constant fixed positive pressure
Not a form of ventilation
Splints airways open
What is the mechanism of NIV?
NIV delivers differing air pressure depending on inspiration and expiration.
The inspiratory positive airways pressure (iPAP) is higher than the expiratory positive airways pressure (ePAP).
Therefore, ventilation is provided mainly by iPAP, whereas ePAP recruits underventilated or collapsed alveoli for gas exchange and allows for the removal of the exhaled gas.
When is NIV indicated? (3)
• COPD with respiratory acidosis (pH <7.35)
• Hypercapnic respiratory failure secondary to chest wall deformity (scoliosis, thoracoplasty) or neuromuscular disease
• Weaning from tracheal intubation
What are some contraindications of CPAP/NIV? (8)
• Vomiting/excess secretions (aspiration risk)
• Confusion/agitation
• Impaired consciousness
• Bowel obstruction
• Facial burns/trauma
• Recent facial/upper gastrointestinal/upper airway surgery
• Inability to protect airway
• Pneumothorax (undrained)
What is extracorpeal membrane oxygenation?
• Blood is removed from the body, passed through a machine where oxygen is added, and carbon dioxide is removed, then pumped back into the body.
When is extracorpeal membrane oxygenation used?
Short term
Only in potentially reversible causes of Resp failure
