Respiratory Failure Flashcards
Define respiratory failure.
syndrome of inadequate gas exchange due to dysfunction of one or more components of the respiratory system
List the components of the nervous system involved in respiratory function.
CNS/brainstem
PNS
NMJ
List respiratory muscles.
diaphragm
thoracic muscles
extra-thoracic muscles
What is the biggest risk factor for males developing chronic respiratory disease?
smoking
What is the biggest risk factor for females developing chronic respiratory disease?
household air pollution from solid fuels
What does ARDS stand for?
acute respiratory distress syndrome
What two factors increase mortality from acute respiratory disease?
severity
advanced age
Give examples of acute pulmonary respiratory disorders.
infection
aspiration
primary graft dysfunction
Give examples of acute extra-pulmonary respiratory disorders.
trauma
pancreatitis
sepsis
Give examples of acute neuro-muscular respiratory disorders.
myasthenia gravis
guillan barre syndrome
Give examples of chronic pulmonary respiratory disorders.
COPD
lung fibrosis
cystic fibrosis
Give examples of chronic musculoskeletal respiratory disorders.
muscular dystrophy
What is type I respiratory failure?
hypoxemic, failure of O2 exchange
[Increased shunt fraction due to alveolar flooding, hypoxemia refractory to supplemental oxygen]
What is type II respiratory failure?
hypercapnic, failure to exchange/remove CO2
[decreased alveolar minute ventilation, dead space ventilation]
What conditions fall under type I respiratory failure?
collapse aspiration pulmonary oedema fibrosis pulmonary embolism pulmonary hypertension
What conditions fall under type II respiratory failure?
muscle failure
airway obstruction
chest wall deformity
What is type III respiratory failure?
perioperative respiratory failure, hypoxaemia or hypercapnoea
[increased atelectasis due to low FRC w/ abnormal abdominal wall mechanics]
Prevention of type III respiratory failure?
anaesthetic or operative technique, posture, incentive spirometry, analgesia, attempts to lower intra abdominal pressure
What is type IV respiratory failure?
describes patients who are intubated and ventilated during shock (septic/ cardiogenic/ neurologic)
List risk factors for chronic respiratory failure.
COPD pollution recurrent pneumonia CF pulmonary fibrosis neuromuscular diseases
List risk factors for acute respiratory failure.
infection aspiration trauma pancreatitis transfusion
List which criteria are used to classify ARDS.
acute onset, ratio PaO2/FiO2 of >200, regardless of positive end-expiratory pressure, bilateral infiltrates seen on frontal chest radiograph, pulmonary artery wedge pressure >18 mm Hg when measured, or no clinical evidence of LA hypertension.
List pulmonary causes of ARDS.
aspiration trauma burns: inhalation surgery drug toxicity infection
List extra-pulmonary causes of ARDS.
trauma pancreatitis burns transfusion surgery bone marrow transplant drug toxicity infection
Response to acute lung injury
damage to interstitium > macrophages release cytokines > IL-6 +TNF alpha > activates TNFR-1 pathway > protein rich oedema > less efficient expanding
migration of neutrophils increases diffusion distance, increases oedema
In vivo evidence of acute lung injury blocking mechanism
reduced injury in TNFR1 animal KO, blocking macrophage activation/ neutrophil migration, DAMP release e.g. HMGB1, cytokines IL6 IL8 IL1B
Therapies tried as pharmacological intervention for ARDS
steroids salbutamol surfactant N-Acetylcysteine neutrophil esterase inhibitor GM-CSF statins
Therapies being trialled for ARDS
mesenchymal stem cells keratinocyte growth factor microvesicles high dose vit C, thiamine, steroids ECCO2R
Underlying distinct biological processes in ARDS
pulmonary vascular endothelialitis
thrombosis
angiogenesis
poor perfusion
List therapeutic interventions to treat underlying disease of respiratory failure.
inhaled e.g bronchodilators, pulm. vasodilators, steriods, antibiotics, antivirals, drugs e.g. pyridostigmine, plasma exchange, IViG, rituximab
List respiratory support therapeutic interventions of respiratory failure.
physiotherapy, oxygen, nebulisers, high flow, oxygen, non-invasive ventilation, mechanical ventilation, extra corporeal support
List cardiovascular support therapeutic interventions of respiratory failure.
fluids
vasopressors
inotropes
pulmonary vasodilators
List renal support therapeutic interventions of respiratory failure.
haemofiltration
haemodialysis
List interventional immune therapies for multiple organ support of respiratory failure.
plasma exchange
convalescent plasma
ARDS and its sequelae include?
poor gas exchange: inadequate oxygenation, poor perfusion, hypercapnoea
infection: sepsis
inflammation, systemic effects
Types of ventilation?
Volume controlled
Pressure controlled
Assisted breathing modes
Advanced ventilatory modes
How is compliance affected in respiratory failure?
reduced
How do you see change in compliance on a pressure-volume loop?
gradient of inspiratory curve is less steep in ARDS lung
What is upper inflection point?
above this pressure, additional alveolar recruitment requires disproportionate increases in applied airway pressure
What is lower inflection point?
can be thought of as minimum baseline pressure needed for optimal alveolar recruitment
pitfalls of ventilation
minute ventilation (PaCO2 control) alveolar recruitment (PEEP) V/Q mismatch (ventilation without gas exchange)
what is breath stacking?
when patients take a breath in, but are unable to get that air out, so it builds up and up in their lungs
breath stacking often occurs in what populations?
severe bronchospasm
COPD
what is driving pressure?
difference between peak and plateau (static) pressure
how to minimise ventilator induced lung injury?
keep driving pressure appropriate
what imaging modalities used to guide diagnosis and treatment in the management of the ARDS?
lung CT
lung ultrasound
how is escalation of therapy guided?
Murray Lung Injury score
what parameters make up the Murray score?
PaO2/FlO2 (on 100% oxygen)
CXR
PEEP
Compliance (ml/cmH20)
a 0 Murray score indicates?
normal
a 1-2.5 Murray score indicates?
mild
a >2.5 Murray score indicates?
severe
a >3 Murray score indicates?
ECMO
inclusion criteria for ECMO?
severe resp. failure (non cardiac cause)
Murray score > or = 3
positive pressure ventilation is not appropriate
when might positive pressure ventilation not be appropriate?
significant tracheal injury
exclusion criteria for ECMO?
contraindication to continuation of active treatment
significant co-morbidity > dependency to ECMO support
significant life limiting co-morbidity
what does ECMO stand for?
extracorporeal membrane oxygenation
what is ECMO?
technique of providing respiratory support; blood is circulated through an artificial lung consisting of two compartments separated by a gas-permeable membrane, blood on one side and ventilating gas on other
