Respiratory failure Flashcards
what is the consequences of oxidising the atmosphere
- Some anaerobes sought anaerobic microenvironments
- Organisms developed defences against oxygen and free radicals
- Animal kingdom developed aerobic metabolism - required mitochondria
how do you work out inspired gas
- Concentration of oxygen in air = 20.94%
- Barometric pressure = 101.3 kPa
- 0.2094 x 101.3 = 21.2
- PO2 of dry air at sea level is 21.2 kPa
why does the partial pressure of oxygen drop when you go up a mountain
- Get PaO2 if you multiply the concentration of oxygen in air x barometric pressure
- When you go up high the barometric pressure drops this is why the partial pressure of oxygen decreases as the oxygen parital pressure remains the same
what causes the PO2 to decrease in tracheal gas
• = PO2 decreases after humidification
how do you work out tracheal gas
- Fractional concentration of oxygen in the dry gas phase x (barometric pressure - SVP)
- FiO2 x (PB - SVP)
- Quantity in parentheses = dry barometric pressure = 95 kPa
- = 0.2094 x (101.3 – 6.3)
- = 19.9 kPa
what factors affect alveolar PO2
- Ventilation
- Oxygen consumption/carbon dioxide production
how do you work out alveolar PO2
- PAO2 = dry barometric pressure x (FiO2-VO2 / VA)
- PAO2 = PiO2 – (PaCO2 / R)
- VO2 – oxygen consumption 3.5ml per kilo per minute
- Pa CO2 – arterial partial pressure
- R – respiratory equation
How do you work out arterial PO2
- The alveolar to arterial PO2 difference is determined by shunting
- The normal A-a O2 difference is not normally greater than 2 kPa
- Normal PaO2 = 13.6 – (0.044 x age in yrs) kPa
- e.g. most of us will have 12.7 kPa 20 yrs, 10.7 kPa 66 yrs
what is a pulmonary shunt
A pulmonary shunt is a pathological condition which results when the alveoli of the lungs are perfused with blood as normal, but ventilation (the supply of air) fails to supply the perfused region
what is the normal range of potassium in the body
the normal range of potassium in the body is 3.5-5.3
how does potassium link to the partial pressure of oxygen and venous blood
the normal range of potassium in the body is 3.5-5.3
10kpa is 94% then you start to desaturate very quickly after than
P50 – this is the parital pressure of oxygen at which haemoglobin is 50% saturated, this is 3.5 KPa
If take venous blood Sv02 this is 5.3
- this is the same reference of potassium
what does oxygen delivery depend on
- oxygen saturation
- haemoglobin concentration
- cardiac output
what is the equation of oxygen delivery
- oxygen delivery = haemoglobin x oxygen saturated of Hb x 1.34x10 x cardiac output
what are the signs of respiratory compensation
- Tachypnoea
- Use of accessory muscles
- Nasal flaring
- Intercostal or suprasternal recession
what are the signs of increased sympathetic tone
- Tachycardia
- Hypertension
- Sweating
what are the signs of respiratory failure
End-organ hypoxia • Altered mental status • Bradycardia and hypotension (late) Haemoglobin desaturation • Cyanosis – don’t go blue until 8Kpa on the partial pressure of oxygen CO2 Retention • Flap • Bounding pulse
what is the definition of type I respiratory failure
– Hypoxaemia only – type I respiratory failure is only type I
– PaO2 < 8 kPa
what is the definition of type II respiratory failure
– Hypoxaemia and hypercapnia
– PaO2 < 8 kPa
– PaCO2 >6.5 kPa
what are the examples of type I respiratory failure
- Pneumonia
- Pulmonary oedema
- Asthma / COPD
- Pulmonary embolism
- Pneumothorax
- Obesity
- Atelectasis
- Collapse
- Pulmonary contusion
what are examples of respiratory failure type II
• Type I with fatigue
• Hypoventilation
Commesnt cause of type II respiratory failure is type I with fatigue
what are types of type II respiratory failure
Causes of hypoventilation (type II respiratory failure) • Brainstem • Metabolic encephalopathy • Depressant drugs • Spinal cord • Nerve root injury • Nerve trauma • Neuropathy • Neuromuscular junction • Respiratory muscles • Airway obstruction • Decreased lung or chest wall compliance
what is treatment of respiratory failure
- oxygen
what is a Hudson mask
- Breath to breath, respiratory rate, tidal volume
- Person to person
- Size of mask, type of mask, vents in mask, fit of mask
the sicker the patient when using the Hudson mask..
the less oxygen they are getting
