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Resp-K -Year 3 > Respiratory failure > Flashcards

Respiratory failure Flashcards

1
Q

Whats resp failure?

What 2 things can cause it?

A

Common medical emergency in A&E with non specific sx, eg mild confusion or agitation.
Oximeter: o2 sats from finger or earlobe- falsy reassuaring - not good when :1. pt is on oxygen. They will not detect alveolar hypoventilation, producing high levels of pCO2.

All unconscious patients should have ABGs taken.

Causes: 1. Resp pump failure 2. I trinsic lung disease

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2
Q

What happens in respiratoty pump failure?

A

Arterial pCO2 is ⬆️.

  1. Severe airflow limitation. Eg COPD
  2. Neurological depression- coma, sedatives, overdose.
  3. Chest wall problem: flail chest, pneumothorax.
  4. Neuromuscular prob- Guillain Barre, old poliomyelitis.
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3
Q

What happens in intrinsic lung disease?

A

(Apart from COPD)- Hypoxaemia is often combined with a reduced PaCO2.

Hypoxaemia arises from V/Q miscmatch. - ventilation perfusion in the pulmonary alveolar bed.
Hypoxic stimulation of ventilation coupled with abnormal respiratoty sensation–> leads to a reduced arterial pCO2 (alveolar hyperventilation).
⬆️ PaCO2 indicated impending resp arrest as it suggests:
1. Either a reductiom in ventilatory effort or
2. A Failure of the respiratory pump.

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4
Q

What should we consider in hypoxia and reduced PaCO2?

A
  • ie HYPERVENTILATION- breathing fast to clear that CO2 out, but no right time to fill lungs with oxygen.
    Infection- eg pneumonia
    Shock- eg sepsis, hypovolaemia, acute lung injury .
    Asthma
    Cardiac disease: eg LVF, pulmonary HTN.
    Pulmonary embolism
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5
Q

Why are ABGs necessary in resp failure?

A

Asses severity
Identify type, alveolar hypo and hyperventilation
Any compensation? Chronicity of problem
A coexisting metabolic acidosis- Base excess.

In ABGS essential to note FiO2- inspiratory o2 concentration.

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6
Q

Respiratory acisosis- what happens?

A
  1. CO2 clearance is reduced.
  2. There is alveolar hypoventilation.
  3. PaCO2 + (H+) rise.
  4. Examples: COPD, flail chest, Guillain -Barre syndrome.
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7
Q

What happens in resp alkalosis?

A
  1. Alveolar hyperventilation and both PaCO2 + H+ are ⬇️.
  2. HCO3 slightly ⬇️.
  3. Examples: Asthma, anxiety attack.
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8
Q

What hapoens in metabolic acidosis?

A
  1. Disturbance of bicarbonate regulation(drops) or H+ production.(goes up?)
  2. HCO3 ⬇️
    Sooooo 3. PaCO2 falls due to resp compensation.- trying to create balance.
  3. Examples: DKA, Renal failure, shock.
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9
Q

Metabolic alkalosis: what hapoens?

A
  1. HCO3 ⬆️. +
  2. Relative hypoventilation–> smaller compensatory increase in PaCO2.
  3. Examples: Xs vomitting, profound hypokalaemia.
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10
Q

What are the common ABG values?

A 
FiO2- 21%. 
pH~7.4
PaO2->10 kPa
PaCO2- 4.5-6 kPa
HCO3- 24-28mmol/L

To convert from kPa to mmHg- multiply by 7.5.
The pH changes by 0.1 per 1kPa change in PaCO2.

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11
Q

What are some common ABG abnormalities?

A
  1. Life threatening asthma
  2. Acute or chronic respiratory F in Pts w/ COPD
  3. Severe pneumonia.
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11
Q

What happens in life threatening asthma attacks?

A 
pH: 7.2
PaO2- 15.4
PaCO2: 6
HCO3: 16.2
BE: -7.3

Note high O2.. Supplemental O2 provided. Metabolic acidosis- pH and BE. As a result of metabolic demands exceeding O2 delivery and producing a lactic acidosis. Airflow limitation limits the normal respiratory compensation to this profound acidosis.

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12
Q

What happens in Resp F in COPD pts?

A 
pH: 7.3
PaO2: 25.2
PaCO2: 12.6
HCO3:42.1- renal compensation
BE: +4.3

Acute or chronic respiratory acidosis exacerbated by a high FiO2 using masks. (40-60% O2)
Patient changed to 28%.
As high oxygen will stop resp drive, letting CO2 to accumulate.

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13
Q

What happens in severe pneumonia? (FiO2 60%)

A 
pH: 7.15
PaO2: 4.8
PaCO2: 3.5
HCO3: 12.5 
BE: -9.3

Despite a high FiO2- pt hypoxaemic cz of ventilation perfusion mismatch. This profound hypozaemia-
Need for urgent intubation and IPPV and are a reflection of circulatory failure resulting from septic shock.

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14
Q

How so we manage resp F?

A

🔸CXR,
🔹Call anaesthetist?
🔸Semi-elective intubation preferred to resp arrest; performed in ward, b4 ICU transfer.

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15
Q

How do we recognise resp arrest?

A

🔹Tachycardia >120
🔸Tachypnoea, RR >30
🔹Hypotension
🔸Sympathetic activation: pale and sweaty, agitation, confusion
🔹Progressive increase in PaCO2 or fall in PaO2
🔸Rapid desaturation on disconnection from O2- eg when drinking or coughing.

Evaluation: end of bed- is pt tired?

16
Q

Treating the cause

A

♦️Tension Pneumothorax- intercostal drain- or large pleural effusion.
🔹Neurological coma: intubation necessary for airway protectiom or to manage ⬆️ICP by hyperventilation.
🔶Drug induced resp F- can be confired by a theraputic trial pf specific antidote- i.e bolus injection naloxone for opiates and flumazanil for benzodiazepines.

🔷Oxygen supplementation- via fixed performance mask in COPD.

17
Q

What are coarse crackles an indication for?

A

Retained secretions eg in COPD.

18
Q

65 Y Male with advanced COPD ADMITTED WITH HX OF COUGH AND PURULENT SPUTUM. his RR was 35, BP 170/90, sweaty, O2 sats 72%, PaO2:5.8, paCO2: 8.1, HCO3: 28.
What do these gases mean?

A

Hypoxaemia withn mild acute resp acidosis. No evidence of chronic resp F with chronically elevated PCO2 as HCO3 is normal. Ie no compensation.

Initial tx at A+E

  1. Nebulised bronchodilators- salbutamol 5mg nebulised. + ipatropium bromide 500mikrograms.
  2. 28% O2 by Venturi mask- controlled mask.
  3. IV amoxicillin( erythromycin if pt pen allergic)
  4. IV steroids- hydrocortisone 100mikrog x3 daily.
  5. Encourage to clear secretions- sit pt up attend physiotherapist.
  6. CXR to exclude pneumothorax or demonstrate assc pneumonia.
19
Q

What do we mean by controlled mask?

A

Venturi mask- leads to intermittent therapy- not tolerated well by agitated or confused breathless patients.

Nasal prongs oxygen at 1/2L/min is more effective and continuous but not controlled.

20
Q

What is non invasive ventilatory support?

A

BiPap with tight fitting facial mask
“Spontaenous pressure support or time breaths” (pressure controlled ventilation.
An exhalation valve reduces re-brreathing.
NIV is succesful in~ 70% of pts with Resp F from COPD.
SHOULD NOT PROCEED if intubation more appropriate.

21
Q

What are some CI of NIV?

A 
Unconsious/ uncooperative
Vomiting
Large amount of resp secretions
Cardiovascularly unstable (beware hypotension)
Recent facial or upper airway surgery
Recent Upper GI surgery
Inability to protect airway by reflexes.
22
Q

Whats mechanical ventilation?
What are the aims of intubation and mechanical ventilation?

Why is hypotension after intubation very common?

A

In an unstable situation- essential to maintain oxygentation.
Refer to ITU for hard intubation pts.

aims of intubation and mechanical ventilation:

  1. Immediat correction of hypoxaemia
  2. Slower correction of hypercapnia
  3. Allow effective suctioning of resp secretions.

Hypotension:

  1. Vasodilation caused by sedatives.
  2. High airway pressures limiting venous return and causing a fall in CO.
  3. A fall in sympathetic tone.

Resp-K -Year 3 (10 decks)

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