Respiratory Failure Flashcards
What is adult respiratory distress syndrome
Fluid accumulation in alveoli due to increased permeability
Non cardiac pulmonary oedema
What are pulmonary causes of adult respiratory distress
Pneumonia Direct lung injury Smoke inhalation Vasculitis Aspiration
What are other causes of RDS
Sepsis Shock Massive haemorrhage Blood transfusion - within 6 hours usually known as TRALI Trauma Head injury = sympathetic = pulmonary hypertension DIC Pancreatitis Liver failure Bypass Drugs / toxins
What are symptoms of RDS
Acute + severe SOB Tachycardia Tachypnoea Cyanosis Bilateral crackles - fine Low sats Hyperaemia Multi-organ failure Signs of hypercapnia if rises
What are symptoms if on ventilatory
Rising ventilatory pressure
What is the criteria for diagnosing RDS
Within 1 week of trigger
Pulmonary oedema on CXR (not explained by collapse or effusion)
Non-cardiogenic cause
PaO2 <40kPa
How do you treat RDS
ITU Oxygen Negative fluid balance - diuretic / haemodialysis Ventilation - low TV CPAP but most need ventilation Organ support Vasopressor to maintain CO Nutrition Treat cause
What are complications of RDS
Scarring
Decreased lung function
What causes atelectasis (collapse)
Post-op
Obstructed airway - COPD / asthma
Basal alveolar collapse
When should you consider atelectasis post op
72 hours
What are the symptoms
SOB Hypoxaemia Resp difficulty Decreased expansion Decreased breath sounds
How do you treat
Chest physio
What is type 1 respiratory failure
PaO2 <8
PaCo2 normal
What causes type 1 respiratory failure
V/Q mismatch
Hypoventilation
Abnormal diffusion
R-L shunt
What can cause a V/Q mismatch (poor perfusion due to barrier to gas exchange)
Pneumonia Pulmonary oedema PE Asthma Emphysema Fibroids RDS
What are the symptoms of type 1
Features of cause Features of hypoxia Restless SOB Agitated Confusion Cyanosis
What happens in long standing type 1
Polycythaemia
Hypertension
Cor pulmonale
How do you Dx
FBC, U+E, CRP ABG CXR Sputum and blood Spirometry
How do you treat type 1
Treat cause Oxygen Monitor O2 with ABG and increase if CO2 stable Assisted ventilation if PaO2 <8 CPAP
Why do you want to control O2 delivery even in type 1
As want to be able to see if condition worsens and sats drop
Why is CPAP only indicated in type 1
Decreases ventilation as no pressure differenece
Can’t be used in type 2 which is due to decreased ventilation
Useful for pulmonary oedema as pushes fluid out
What does CPAP do
Stops lungs collapsing so increases O2 delivery
Can be delivered through high flow nasal cannula - 40l
What is O2 a good marker of
Diffusion i.e. in oedema / infection
What is CO2 a good marker of
Poor ventilation
Very soluble so shouldn’t be affected by diffusion issues
What is type 2 resp failure
PaO2 <8
PaCO2 >6
What causes type 2 respiratory failure
Alveolar hypoventilation with or without V/Q mismatch Ventilation issue Asthma COPD OSA Fibrosis Drugs CNS tumour Trauma Neuromuscular Thoracic wall disease
How does type 2 present
Hypercapnia Headache Peripheral vasodilation Tachycardia Bounding pulse Tremor Papilloedema Confusion Drowsy Coma
How do you treat type 2
Treat underlying cause Beware of hypoxic drive Controlled O2 Check ABG regularly Consider NIPPV if CO2 rising Bipap Intubation if this fails ECMO
What do you start at
24%
What do you aim sats to be
88-92%
Consequences
Acidosis
What is cor pulmonale
RHF due to pulmonary hypertension caused by respiratory disease
What causes cor pulmonale
Chronic lung disease
- COPD = most common
- Fibrosis
- Severe asthma
- Bronchiectasis
- CF
Pulmonary vascular - PE - Vasculitis - PPH - ARDS - Sickle Neuromuscular - MS / MG Chest deformity / scoliosis Hypoventilation - OSA / adenoids Cerebrovascular
What are symptoms of cor pulmonate
Asymptomatic Dyspnoea = main Sx Fatigue Syncope CYanosis Tachycardia Raised JVP RV heave Loud P2 Pansystolic murmur - tricuspid regurgitation Hepatomegaly Peripheral oedema
How do you investigate
FBC - polycythaemia
ABG
CXR
ECG - RAD / RVH
Wha will CXR show
Enlarged RA and RV
Prominent pulmonary arteries
How do you treat cor pulmonale
Treat cause Treat res failure Treat cardiac failure LTOT often needed Venesection if haemocrit >55% Heart and lung transplant in the young
What causes chronic ventilatory failure
Extreme OSA COPD Bronchiectasis Chest wall abnormality Resp muscle weakness e.g. MND Central hypoventilation
What are the symptoms of chronic ventilatory failure
SOB Orthopnoea Oedema 2 cor pulmonale Morning headache due to rise in CO2 Chest infection Disturbed sleep
What does blood gas show
Elevated CO2
Decreased O2
How do you investigate chronic ventilatory failure
Lung function test
Overnight oximetry
CO2 monitoring
Spirometry
Spirometry shows
Restrictive
Drop in vital capacity lying flat
How do you treat
Non-invasive ventilation
Oxygen
Tracheostomy if pH <7.25
Indications for non-invasive ventilation
COPD with pH 7.25-7.35
Type 2 res failure
Cardiopulmonary oedema resistant to CPAP
Weaning from tracheostomy
What excludes cardiac cause for ARDS
Normal capillary wedge pressure
When is ventilation indicated
pH <7.25
What is CPAP
Continuous +Ve airway pressure
Keeps airway expanded so air can move in and out
What are indications for CPAP
OSA
CCF
Acute pulmonary oedema
What is BiPAP
Bilevel +Ve airway pressure
Involves high or low pressures to correspond to ventilation
When is it used
Type 2 resp failure
Usually due to COPD
If pH <7.35 despite medical therapy
What does non-invasive ventilation mean?
- Non-invasive ventilation (NIV) delivers ventilatory support to improve respiratory failure via an inter- face that does not cross the larynx.
What is CPAP?
- CPAP applies a constant pressure throughout the respiratory cycle and works by splinting open and recruiting collapsed alveoli, thus reducing pulmonary circulatory shunting and improving lung compli- ance.
- This improves oxygenation and reduces the work of breathing.
- CPAP is often included under NIV, technically it does not provide ventilatory support as there is no assistance with inspiration.
Indications for CPAP [3]
- Worsening Type 1 respiratory failure by either bridging to or avoiding intubation.
- Acute cardiogenic pulmonary oedema by improving lung compliance and oxygenation when drug treatment has been optimised. CPAP also assists in the translocation of interstitial fluid to the alveolar capillaries surrounding the alveoli, further improving gas exchange.
- In the domiciliary setting, CPAP can be used as a treatment of obstructive sleep apnoea/ hypoapnoea syndrome (OSAHS) by splinting open the airways and improving oxygenation.
Indications for NIV [3]
- Acute exacerbation of COPD
- Decompensated OSA
- Respiratory failure secondary to neuromuscular weakness or chest wall deformity.
Patient monitoring on non-invasive ventilation or CPAP [2]
- For both CPAP and NIV, there should be continuous pulse oximetry and ECG monitoring for the first 2 hours, and regular RR, pulse, BP measurements and assessments of consciousness.
- ABG should be taken as a minimum at 1, 4 and 12 hours after the initiation of NIV. This will guide changes in settings, escalation plans to intubation and ceilings of treatment.
Contraindications for non-invasive ventilation [7]
- Impaired consciousness or confusion – the patient will not be able to trigger sufficient breaths and should be assessed for intubation immediately.
- Life-threatening hypoxaemia.
- Haemodynamic instability or arrest. NIV reduces preload so can lower blood pressure further, so patients should be considered for admission to ICU.
- Facial surgery or burns.
- Undrained pneumothorax: the positive pressure ventilation may convert a simple pneumothorax to
a tension pneumothorax. - Vomiting.
- Inability to protect airway, e.g. GCS < 8.
