Cardio - Respiratory Failure Flashcards
(48 cards)
What is respiratory failure?
Syndrome of inadequate gas exchange due to dysfunction of one or more components of the respiratory system
What are the 3 parts of the respiratory system that could be affected?
→ nervous system
→ respiratory muscle
→ pulmonary
What are the 3 ways of classifying respiratory failure?
→ acute
→ chronic
→ acute on chronic
What are the different types of acute respiratory failure?
→ pulmonary : infection, aspiration, primary graft dysfunction ( Lung Tx)
→ extra-pulmonary : trauma, pancreatitis, sepsis
→ neuro-muscular : myasthenia / GBS
What are some examples of chronic respiratory failure?
→ pulmonary / airways : COPD, lung fibrosis, CF, lobectomy
→ musculoskeletal : muscular dystrophy
What is acute on chronic respiratory failure?
→ infective exacerbation (e..g COPD, CF)
→ myasthenic crises
→ post-operative
What is ARDS?
Acute Respiratory Distress Syndrome
What factors are considered in order to classify ARDS?
→ timing : within 1 week of a known clinical insult or new or worsening symptoms
→ chest imaging : bilateral opacities - not fully explained by effusions, lobar / lung collapse, or nodules
→ respiratory failure not fully explained by cardiac failure or fluid overload
→ oxygenation levels determine severity
How is respiratory failure physiologically classified?
→ Type 1 or Hypoxemic
→ Type 2 or Hypercapnic
What is Type 1 respiratory failure?
→ Hypoxemic
→ failure of oxygen exchange
→ increased shunt fraction (QS / QT) due to alveolar flooding
→ hypoxemia refractory to supplemental oxygen
What oxygen levels are classified as Type 1 RF?
PaO2 < 60
What are the causes of Type 1 RF?
→ collapse → aspiration → pulmonary odema → fibrosis → pulmonary embolism → pulmonary hypertension
What is Type 2 RF?
→ hypercapnic
→ failure to exchange or remove CO2
→ decreased alveolar minus ventilation
→ dead space ventilation
What CO2 levels classify as Type 2 RF?
PaCO2 > 45
What are the causes of Type 2 RF?
→ nervous system → neuromuscular → muscle failure → airway obstruction → chest wall deformity
What is Type 3 RF?
→ peri-operative respiratory failure
→ Increased atelectasis (lung collapse) due to low functional residual capacity
→ (FRC) with abnormal abdominal wall mechanics
→ Hypoxaemia or hypercapnoea
How can Type 3 RF be prevented?
anesthetic or operative technique, posture,
incentive spirometry, analgesia, attempts to lower intra- abdominal pressure
What is Type 4 RF?
→ shock
→ 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 risk factors for chronic RF?
→ COPD → pollution → recurrent pneumonia → CF → pulmonary fibrosis → neuro-muscular diseases
What are the risk factors for acute RF?
→ infection (viral, bacterial) → aspiration → trauma → pancreatitis → transfusion
What are some pulmonary causes of ARDS?
→ aspiration → trauma → burns (inhalation) → surgery → drug toxicity → INFECTION
What are some extra-pulmonary causes of ARDS?
→ Trauma → Pancreatitis → Burns (extra-thoracic) → Transfusion → Surgery → BM transplant → Drug Toxicity → INFECTION
What are the 4 major steps that drive ARDS?
→ infection or damage to the lung
→ immune response form macrophage already existing in the lung occurs - release IL-6, IL-8 + TNF-alpha
→ inflammation occurs due to signalling pathway, causing oedema
→ leucocyte migration into alveolar causes oedema to worsen
What has been the in vivo evidence for the mechanism of action for ARDS?
→ TNF signalling implicated → leucocyte activation + migration → DAMP release → cytokine release of IL-6, IL-1B, IFN-y → cell death (becrosis in lung biopsies, apoptotic mediators, FAS, FAS-1, BCI-2)
