Respiratory failure Flashcards
Define respiratory failure:
Syndrome of inadequate gas exchange due to dysfunction of one or more components of the respiratory system
What 3 main areas can be affected by respiratory failure?
Nervous system;
CNS/Brainstem
Peripheral nervous system
Neuro-muscular junction
Respiratory Muscle;
Diaphragm & thoracic muscles
Extra-thoracic muscles
Pulmonary:
Airway disease
Alveolar-capillary
Circulation
What is the epidemiology of Chronic respiratory disease?
Chronic respiratory disease 3rd leading cause of death* (2017) 39.8% rise from 1990
Males: Smoking biggest risk factor
Women: Household air pollution from solid fuels
Costs: EU 380m Euro’s annually (2019) care for chronic respiratory disorders
Accounts for: Inpatient care, lost productivity
Despite extensive costs: limited granular data
What is the epidemiology of Acute respiratory failure?
Limited data:
Heterogenous disease presentation
Acute respiratory distress syndrome
Prevalence: 6-7 per 100,000 = 6-700 people/yr in UK
30 to 40% Mortality (ALIEN/Esteban)
35, 40 and 46% (Severity dependent. Bellani)
Severity and advance age
increase mortality
What are the causes for Acute respiratory failure?
Pulmonary: Infection, aspiration, Primary graft dysfunction (Lung Tx)
Extra-pulmonary: Trauma, pancreatitis, sepsis,
Neuro-muscular: Myasthenia/GBS
What are the causes for Chronic respiratory failure?
Pulmonary/Airways: COPD, Lung fibrosis, CF, lobectomy
Musculoskeletal: Muscular dystrophy
What are the causes for Acute on Chronic respiratory failure?
Infective exacerbation
COPD, CF
Myasthenic crises
Post operative
What are the reasons for & criteria for Type 1 Respiratory failure?
Reasons; Collapse Aspiration pulmonary oedema Fibrosis Pulmonary embolism Pulmonary hypertension
Criteria; (PaO2 <60 at sea level): Failure of oxygen exchange n Increased shunt fraction (Q S /QT ) n Due to alveolar flooding n Hypoxemia refractory to supplemental oxygen
What are the reasons for & criteria for Type 2 Respiratory failure?
Nervous system Neuromuscular Muscle failure Airway obstruction Chest wall deformity
(PaCO2 >45): Failure to
exchange or remove carbon dioxide
n Decreased alveolar minute ventilation (V A )
n Dead space ventilation
What are the features of Type 3 Respiratory failure?
Increased atelectasis due to low functional residual capacity
(FRC) with abnormal abdominal wall mechanics
n Hypoxaemia or hypercapnoea
n Prevention: anesthetic or operative technique, posture,
incentive spirometry, analgesia, attempts to lower intra- abdominal pressure
What are the features of Type 4 Respiratory failure?
Type IV describes patients who are intubated and ventilated
During shock (Septic/cardiogenic/neurologic)
n 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 risk factors for Chronic Respiratory failure?
COPD Pollution Recurrent pneumonia Cystic fibrosis Pulmonary fibrosis Neuro-muscular diseases
What are the risk factors for Acute Respiratory failure?
Infection Viral Bacterial Aspiration Trauma Pancreatitis Transfusion
What is the first thing to look for in Acute Respiratory failure?
Origin of shortness of breath
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 is the alveolar macrophage response in ARDS?
Release cytokines; IL-6,8, TNF-alpha.
Alveolar fluid build up, inactivation of surfactant, alveolar expansion defficiency.
Increased Oedema causes greater distance between the alveolus & capillary. Greater distance for gas exchange response, less efficient.
What are the mechanisms that lead to inefficient gas exchange in the lung in ARDS?
Leucocytes
Inflammation
Infection
Immune response
What happens in Neutrophil lung migration?
Inflammation causes migration of neutrophils out of the blood vessels into the interstitium where they cause damage through secretion of cytokines and proteases.
Increased Oedema causes greater distance between the alveolus & capillary. Greater distance for gas exchange response, less efficient.
What are some possible explanations as to why certain patients have a more severe response to viral infections?
TNF signalling implicated in vivo and in vitro
Leucocyte migration and activation
DAMP release; HMGB-1, RAGE.
Cytokine release IL-6,8,1B,IFN-y
Cell death - necrosis in lung biopsies
- Apoptotic mediators; FAS, FAS-I, BCI-2.
What are some Pharmacological interventions available for ARDS?
Steroids Salbutamol Surfactant N-Acetylcysteine Neutrophil esterase inhibtitor GM-CSF Statins
How do you treat the underlying disease in Respiratory failure?
Inhaled therapies Bronchodilators Pulmonary vasodilators Steroids Antibiotics Anti-virals
Drugs Pyridostigmine Plasma exchange IViG Rituximab
What respiratory support would you provide in respiratory failure?
Physiotherapy Oxygen Nebulisers High flow oxygen Non invasive ventilation Mechanical ventilation Extra-corporeal support
What organ support would you provide in respiratory failure?
Cardiovascular support Fluids Vasopressors Inotropes Pulmonary vasodilators Renal support Haemofiltration Haemodialysis Immune therapies Plasma exchange Convalescent plasma
What happens sequentially in ARDS?
Poor gas exchange
Inadequate oxygenation
Poor perfusion
Hypercapnoea
Infection
Sepsis
Inflammation
Inflammatory response
Systemic effects
What are the 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
What is Compliance
amount of lung that opens for the amount of pressure that you use.
What is the upper inflection point?
Above this pressure additional alveolar recruitment requires disproportionate increases in applied airway pressure.
What is the lower inflection point?
Can be thought of as the minimum baseline pressure needed for optimal alveolar recruitment.
What are some of the Pitfalls of ventilation?
In complications with asthma and COPD you can get trapping of air in the lung which leads to breath stacking, so the chest becomes fuller and fuller, making CO2 management harder.
What scoring system is used to escalate therapy?
Murray score 0 = normal 1-2.5 Mild 2.5 Severe 3 ECMO
What is the Inclusion criteria for ECMO 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 for ECMO treatment?
- Contraindication to continuation of active treatment;
- Significant co-morbidity dependency to ECMO support
- Significant life limiting co-morbidity
What is the process for ECMO?
Cannula through femoral vein, pumps blood from IVC out where it comes across an artificial membrane that oxygenates the blood, and returns it to the patient also through a femoral vein.
What are some issues with ECMO?
Time to access Referral system - geographical inequality Obtaining access; Internal jugular subclavian femoral Circuit Haemodynamics Clotting/Bleeding Cost
Name 2 imaging modalities that can be used to guide diagnosis and treatment in the management of the acute respiratory distress syndrome?
CT scan
Lung ultrasound
