Respi - pathophysiology of RF

Question 1

respiratory failure definition

Answer 1

inadequate gas exchange due to dysfunction of the resp system
-> inability to maintain O2/CO2 (hypoxia/hypercapnia)

due to alveolar problems or ventilation problems

Question 2

measurement of oxygenation

Answer 2

• pulse oximeter

- arterial blood gas

Question 3

parts of the resp system that failes -> resp failure

Answer 3

CCAAP

• CNS and nerves - controls ventilation
• chest wall, diaphragm

within lungs

• airways
• alveolar-capillary barrier
• pulmonary circulation

Question 4

symptoms of resp failure

Answer 4

• breathlessness - air hunger
• hypoxia: confusion, coma
  long standing hypoxia: pulmonary HTN, right heart strain
  cause of hypoxia -> compensatory response: stimulated erythropoietin release from kidney = polycythaemia

Question 5

type 1 resp failure

- causes

Answer 5

hypoxaemia w/o hypercapnia (decrease CO2 cause of hyperventilation compensation)

caused by alveolar-capillary barrier (PALL)

• alveolar spaces filled w/ fluid/pus
• pulmonary embolism: ventilate but cannot perfuse
• lung collapse
• irreversible loss of alveoli

should observe closely to prevent progression to type 2 resp failure

Question 6

type 2 resp failure

- causes

Answer 6

hypoxemia w/ hypercapnia
cause of poor ventilation -> retention of CO2

causes: (CAN)
- failure of neuromuscular system
- failure of chest wall mechanics
- airway obstruction

Question 7

vascular diseases

Answer 7

• pulmonary edema
• pulmonary HTN
• cor pulmonale
• pulmonary embolism
• vasculitis
• atelactis

Question 8

pulmonary edema causes

Answer 8

• pulmonary capillary congestion due to LH failure (backpressure effect)
• > increased extravated fluid in interstitium - fluid in alveolar spaces

-> capillary could also rupture -> leakage into interstitium

Question 9

pulmonary HTN causes

Answer 9

• left heart failure/ mitral regurgitation : backpressure effect on pulmonary system
• L->R shunt : increase blood flow through pulmonary circulation
• chronic lung disease - loss of normal capillaries + hypoxic vasoconstriction of arterioles
• pulmonary embolism
• idiopathic causes

Question 10

pulmonary HTN pathogenesis

Answer 10

sustained increase in pressure in the pulmonary system -> irreversible changes in arteries

• arteries become hypertrophied/ proliferate
• > narrowing/ occlusion
• > increase pressure even more in arteries

Question 11

cor pulmonale

Answer 11

heart failure secondary to lung failure (lung failure caused the HF)
cause of high pressure in pulmonary system - RH needs to pump against the high pressure

Question 12

pulmonary emboli effects

Answer 12

• circulatory collapse (large)
• infarction - rare (cause lung got dual blood supply from bronchial artery also)
  haemorrhagic , wedge shaped peripheral lesions -> peripheral scar when healed
• V/Q mismatch
• recurrent small thromboemboli may progress to permanent occlusion -> pulmonary HTN

Question 13

vasculitis cause

+ syndromes associated

Answer 13

inflammatory destruction of blood vessels -> bleeding into lungs

• Wegener’s granulomatosis - affects nose, lungs, kidneys
• Churg-strauss syndrome - infiltration by eosinophils. pt presents w/ asthma

Question 14

atelectasis

Answer 14

lung collapse

lung cannot expand fully - decrease lung vol

Question 15

causes of atelectasis (3)

Answer 15

• resorption: airway obstruction
• compression: post-op/ pneumo/haemothorax/ effusion
• contraction: scarring of lungs - restricts expansion