Respiratory failure Flashcards

1
Q

what is the consequences of oxidising the atmosphere

A
  1. Some anaerobes sought anaerobic microenvironments
  2. Organisms developed defences against oxygen and free radicals
  3. Animal kingdom developed aerobic metabolism - required mitochondria
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2
Q

how do you work out inspired gas

A
  • 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
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3
Q

why does the partial pressure of oxygen drop when you go up a mountain

A
  • 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
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4
Q

what causes the PO2 to decrease in tracheal gas

A

• = PO2 decreases after humidification

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5
Q

how do you work out tracheal gas

A
  • 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
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6
Q

what factors affect alveolar PO2

A
  • Ventilation

- Oxygen consumption/carbon dioxide production

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7
Q

how do you work out alveolar PO2

A
  • 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
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8
Q

How do you work out arterial PO2

A
  • 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
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9
Q

what is a pulmonary shunt

A

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

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10
Q

what is the normal range of potassium in the body

A

the normal range of potassium in the body is 3.5-5.3

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11
Q

how does potassium link to the partial pressure of oxygen and venous blood

A

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
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12
Q

what does oxygen delivery depend on

A
  • oxygen saturation
  • haemoglobin concentration
  • cardiac output
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13
Q

what is the equation of oxygen delivery

A
  • oxygen delivery = haemoglobin x oxygen saturated of Hb x 1.34x10 x cardiac output
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14
Q

what are the signs of respiratory compensation

A
  • Tachypnoea
  • Use of accessory muscles
  • Nasal flaring
  • Intercostal or suprasternal recession
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15
Q

what are the signs of increased sympathetic tone

A
  • Tachycardia
  • Hypertension
  • Sweating
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16
Q

what are the signs of respiratory failure

A
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
17
Q

what is the definition of type I respiratory failure

A

– Hypoxaemia only – type I respiratory failure is only type I
– PaO2 < 8 kPa

18
Q

what is the definition of type II respiratory failure

A

– Hypoxaemia and hypercapnia
– PaO2 < 8 kPa
– PaCO2 >6.5 kPa

19
Q

what are the examples of type I respiratory failure

A
  • Pneumonia
  • Pulmonary oedema
  • Asthma / COPD
  • Pulmonary embolism
  • Pneumothorax
  • Obesity
  • Atelectasis
  • Collapse
  • Pulmonary contusion
20
Q

what are examples of respiratory failure type II

A

• Type I with fatigue
• Hypoventilation
Commesnt cause of type II respiratory failure is type I with fatigue

21
Q

what are types of type II respiratory failure

A
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
22
Q

what is treatment of respiratory failure

A
  • oxygen
23
Q

what is a Hudson mask

A
  • Breath to breath, respiratory rate, tidal volume
  • Person to person
  • Size of mask, type of mask, vents in mask, fit of mask
24
Q

the sicker the patient when using the Hudson mask..

A

the less oxygen they are getting

25
Q

how can you give oxygen

A

Oxygen masks (Hudson mask), nasal cannulae
• Patient with normal vital signs (post-op)
Face mask with reservoir bag
• Higher O2 concentration needed (asthma attack, pneumonia, sepsis)
Venturi mask
• Controlled treatment in long-term respiratory failure (COPD)
• Also called fixed performance systems

26
Q

what are the venturi colour and the flow rate and the oxygen delivered

  • blue
  • white
  • yellow
  • red
  • green
A
  • blue - 2 l/min 24 oxygen delivered
  • white - 4l/min 28 oxygen delivered
  • yellow 6 l/min 35 oxygen delivered
  • red 8 l/min 40 oxygen delivered
  • green - 12 l/min 60 oxygen delivered
27
Q

what is the critical saturation of oxygen threshold

A

• A pulse oximetry saturation (SpO2) ~94% is a critical threshold. Below this level a small fall in PaO2 produces a sharp fall in SpO2

28
Q

what does pulse oximetry tell us about

A

• Pulse oximetry only tells us about oxygenation NOT ventilation

29
Q

what are the sources of error of pulse oximetry

A
  • Poor peripheral perfusion
  • Dark skin (oximeter over-reads slightly)
  • False nails or nail varnish
  • Lipaemia / hyperlipidaemia / propofol infusion
  • Bright ambient light
  • Poorly adherent probe
  • Excessive motion
  • Carboxyhaemoglobin (SpO2 > SaO2)
30
Q

if the SpO2 is greater than 94% then the PaO2 is…

A

• If the SpO2 is >94% the the PaO2 should be >10kPa

31
Q

what do high concentration of oxygen do

A

• High concentrations of oxygen produce free radicals that can damage the body

32
Q

why does carbon dioxide decrease in type 1 respiratory failure

A

In type I respiratory failure the carbon dioxide goes down as your trying to get rid of the carbon dioxide

33
Q

what is the COPD retainer type of patient

A

• Only 10% of all COPD Patients

If uncertain if CO2 retainer and acutely unwell
• Start high flow oxygen.
• Monitor for drowsiness / signs of CO2 retention.
• Check ABGs after 30 minutes
• They relie on the hypoxia to drive there breathing
• So if you give them oxygen and there no longer hypoxic then they stop breathing
• Therefore they are given the venturi masks

34
Q

how do you treat at COPD patient normally

A
  • Controlled mask
  • Titrate - use lowest O2 possible
  • Aim for sats 90% - 92% (may need 85%+)
  • Measure ABGs ASAP
  • Repeat ABGs after 30 mins of O2 change
  • Requiring 60% oxygen to maintain sats
  • Severe tachypnoea (e.g. > 30 bpm)
  • Confusion / LOC
  • pH < 7.20
  • pCO2 > 8kPa
35
Q

when is ventilation used

A
  • Not for hypoxia
  • Used for hypercapnea
  • i.e. give oxygen in hypoxia and ventilate in hypercapnea (= hypoventilation)