Respiratory Failure Flashcards
What is a respiratory infection?
Syndrome of inadequate gas exchange due to dysfunction of one or more components of the respiratory system
Where does a respiratory infection affect?
Nervous system
CNS/Brainstem
Peripheral nervous system
Neuro-muscular junction
Respiratory muscle
Diaphragm & thoracic muscles
Extra-thoracic muscles
Pulmonary
Airway disease
Alveolar-capillary
Circulation
In men and women, what is the biggest risk factor for chronic respiratory disease?
Males: Smoking biggest risk factor
Women: Household air pollution from solid fuels
How does ventilation across the lung work?
PPL is more negative (-8 cmH2O)
Greater transmural pressure gradient (0 vs. -8)
Alveoli larger and less compliant
Less ventilation
PPL is less negative (-2 cmH2O)
Smaller transmural pressure gradient (0 vs. -2)
Alveoli smaller and more compliant
More ventilation
How does perfusion across the lung work?
Lower intravascular pressure (gravity effect)Less recruitment
Greater resistance
Lower flow rate
Higher intravascular pressure
(gravity effect)
More recruitment
Less resistance
Higher flow rate
Describe oxygen transport when loading in the lungs?***
Describe the pulmonary transit time?
Ventilation perfusion matchin?
Describe the structural properties of lung tissue*
COMPLIANCE
The tendency to distort under pressure
𝑪𝒐𝒎𝒑𝒍𝒊𝒂𝒏𝒄𝒆= ∆𝑽/∆𝑷
ELASTANCE
The tendency to recoil to its original volume
𝑬𝒍𝒂𝒔𝒕𝒂𝒏𝒄𝒆= ∆𝑷/∆𝑽
What is an acute respiratory disorder
Pulmonary: Infection, aspiration, Primary graft dysfunction (Lung Tx)
Extra-pulmonary: Trauma, pancreatitis, sepsis,
Neuro-muscular: Myasthenia/GBS
What is a chronic respiratory disorder
Pulmonary/Airways: COPD, Lung fibrosis, CF, lobectomy
Musculoskeletal: Muscular dystrophy
What is an acute on chronic respiratory disorder
Infective exacerbation
COPD, CF
Myasthenic crises
Post operative
Lung volumes and capacities?*
How to work out minute ventilation?
Gas entering and leaving the lungs
Tidal volume x Breathing frequency
How to work out alveolar ventilation?
(Tidal volume - Dead space) x Breathing Frequency
What is the physiologic classification in terms of type I?
Type I or Hypoxemic (PaO2 <60 at sea level):
Failure of oxygen exchange
-Increased shunt fraction (Q S /QT )
-Due to alveolar flooding
-Hypoxemia refractory to supplemental oxygen
What is the physiologic classification in terms of type II?
Type II or Hypercapnic (PaCO2 >45): Failure to
exchange or remove carbon dioxide
-Decreased alveolar minute ventilation (V A )
-Dead space ventilation
What is the physiologic classification in terms of type III?
Type III Respiratory Failure: Perioperative respiratory
Failure
-Increased atelectasis due to low functional residual capacity
(FRC) with abnormal abdominal wall mechanics
-Hypoxaemia or hypercapnoea
-Prevention: anesthetic or operative technique, posture,
incentive spirometry, analgesia, attempts to lower intra- abdominal pressure
What is the physiologic classification in terms of type IV?
-Type IV describes patients who are intubated and ventilated
During shock (Septic/cardiogenic/neurologic)
-Optimise ventilation improve gas exchange and to unload the
respiratory muscles, lowering their oxygen consumption
Ventilatory effects on right and left heart
Reduced afterload (good for LV) Increased pre-load (bad for RV)
What are the chronic risk factors?
COPD
Pollution
Recurrent pneumonia
Cystic fibrosis
Pulmonary fibrosis
Neuro-muscular diseases
What are the acute risk factors?
Infection
Viral
Bacterial
Aspiration
Trauma
Pancreatitis
Transfusion
In acute respiratory failure, what can the origin of shortness of breath be?
Lower respiratory tract infection
Viral
Bacterial
Aspiration
Trauma
Transfusion
Pulmonary vascular disease
Pulmonary embolus
Hemoptysis
Extrapulmonary pancreatitis, new medications
What are the pulmonary causes of ARDS?
Aspiration
Trauma
Burns: Inhalation
Surgery
Drug Toxicity
Infection
What are the extra pulmonary causes of ARDS?
Trauma
Pancreatitis
Burns
Transfusion
Surgery
BM transplant
Drug Toxicity
Infection
What id driving the response in acute lung injury?
The lung
Leucocytes
Inflammation
Infection
Immune response
What is the in vivo evidence for respiratory failure?
TNF signalling implicated in vivo and in vitro
Reduced injury in TNFR-1 animal KO
Leucocyte activation and migration
Macrophage activation: alveolar
Neutrophil lung migration
DAMP release: HMGB-1 and RAGE
Cytokine release IL-6,8,IL-1B, IFN-y
Cell death
Necrosis in lung biopsies
Apoptotic mediators: FAS, FAS-l, BCl-2
What therapies tried pharmacological interventions?
Steroids
Salbutamol
Surfactant
N-Acetylcysteine
Neutrophil esterase inhibtitor
GM-CSF
Statins
What pharmacological interventions being trialled?
Mesenchymal stem cells
Ex-vivo benefit
Keratinocyte growth factor
Repair factor
Microvesicles
High dose Vitamin C, thiamine, steroids…
ECCO2R
What inflammatory endotypes are there in pro-inflammatory ARDS?
Hyper and Hypo
What are 3 therapeutic interventions for respiratory disorders?
Treat underlying disease
Respiratory support
Multiple organ support
Describe how an underlying disease can be treated
Inhaled therapies
Bronchodilators
Pulmonary vasodilators
Steroids
Antibiotics
Anti-virals
Drugs
Pyridostigmine
Plasma exchange
IViG
Rituximab
Describe how respiratory support can be given
Physiotherapy
Oxygen
Nebulisers
High flow oxygen
Non invasive ventilation
Mechanical ventilation
Extra-corporeal support
Describe how multiple organ support can be given
Cardiovascular support
Fluids
Vasopressors
Inotropes
Pulmonary vasodilators
Renal support
Haemofiltration
Haemodialysis
Immune therapies
Plasma exchange
Convalescent plasma
What is the sequelae of ARDS
Poor gas exchange
Inadequate oxygenation
Poor perfusion
Hypercapnoea
Infection
Sepsis
Inflammation
Inflammatory response
Systemic effects
What are specific interventions for ARDS?
Respiratory support
Intubation and ventilation
ARDS necessitates mechanical intervention
Types of ventilation
Volume controlled
Pressure controlled
Assisted breathing modes
Advanced ventilatory modes
Procedures to support ventilation
Explain the parts of the pressure-volume loop?***
What are the pitfalls of ventilation?
Minute ventilation
PaCO2 control
Alveolar recruitment
Positive end exspiratory pressure (PEEP)
V/Q mismatch
Ventilation without gas exchange vice-versa
What is the murray score?
Guides the escalation for therapy
0=normal
1-2.5 = Mild
2.5 = Severe
3 = ECMO
What is the national ARDS approach?
5 national centres
Telephone or online referral
Murray score > 3
pH < 7.2
Consultant case review
Transfer of imaging
Advice
Retrieval
Transfer
Ongoing management
What is the inclusion criteria in terms of treatment?
- severe respiratory failure
non-cardiac cause (i.e. Murray Lung Injury score 3.0 or above) - Positive pressure ventilation is not appropriate (e.g. significant tracheal injury).
What is the exclusion criteria in terms of treatment?
- Contraindication to continuation of active treatment;
- Significant co-morbidity dependency to ECMO support
- Significant life limiting co-morbidity
What is an ECMO?
First major trial EOLIA
Stopped early for futility
Statistically no significant difference….
RBH survival 79%
Best study mortality 24 to 31%
? Case selection important
What are the issues for an ECMO?
What are technicalities?
Time to access
Referral system- Geographical inequity
Consideration of referral
Obtaining access:
Internal jugular
Subclavian
Femoral
Circuit
Haemodynamics
Clotting/Bleeding
