Disoders of Ventilation

1
Disoders of Ventilation

• Sung Chul Hwang, M.D.
• Dept. of Pulmonary and Critical Care Medicine
• Ajou University School of Medicine

2
Chemoreceptor

• Central
• Medulla Oblongata
• pH, PaCO2, PaO2
• fall in pH of ECF and Carotid body
• Fine regulation

• Peripheral
• Aortic and Carotid body
• PaO2
• dominant during Chronic hypoxia
• Coarse regulation

3
Alveolar Hypoventilation

• Increased PACO2 PaCO2 above normal
• Impaired respiratory drive brain stem, carotid
  body trauma
• Reduction in over all minute ventilation resp.
  muscles, spinal cord, peripheral nerves
• Impaired respiratory apparatus chest wall,
  airways and lung

4
Neuromuscular Disorders

• Spinal cord, peripheral nerves, respiratory
  muscle disease
• orthopnea, paradocxical movement of abdomen and
  diaphragm
• Dx Rapid deterioration of MVV, reduced Pimax,
  Pemax, reduced transdisphragmatic pressures and
  response to phrenic nerve stimulations

5
Pathophysiology

• Increased PACO2 PaCO2
• Respiratpory Acidosis
• Metabolic compensation -- increase in HCO3 --
• Decrease in Cl -
• Decrease in PAO2 PaO2
• Pulmonary vasoconstriction, Pulmonary
  hypertension, RV hypertrophy, CHF
• (Cor pulmonale)

6
Mechanoreceptor

• Stretch receptor smooth muscle of trachea and
  main bronchus
• Irritant receptor beneath the epithelium of
  larynx, trachea, bronchi
• J- receptor periphery of lung
• C- receptor pulmonary interstitial space near
  pulmonary and bronchial circulation

7
Clinical features

• Hypoxemia, cyanosis, polycythemia
• chronic hypoxemia , hypercapnea, pulmonary HTN,
  CHF
• ABG abnormality esp. in sleep and sleep
  disturbances
• Sx morning headache, fatigue, daytime
  somnolence, mental confusion, intellectual
  impairment
• specific features of underlying diseases

8
Diagnosis

• Defect in Control System impaired response to
  chemical stimuli, able to hyperventilate
  voluntarily
• Defects in N-M System Unable to hyperventilate,
  abnormal static and dynamic lung measurements
• Defects in Chest wall, Lungs, Airways Abnormal
  airway resistance and compliance, widened (A-a)
  DO2

9
Treatment

• Treat individual underlying disease
• Correction of Metabolic Alkalosis
• O2 supplements
• Respiratory Stimulants (medroxyprogesterone)
• Mechanical Ventilation especially during sleep
• Diaphragmatic pacing

10
Primary Alveolar Hypoventilation(Ondines Curse)

• Chronic hypoxemia and hypercapnea without
  identifiable cause
• defect in metabolic respiratory control
• 20 - 50 yrs of age males
• Sx and Signs of alveolar hypoventilation
• treatment general supportive care for
  hypoventilation

11
Obesity-Hypoventilation SD (Pickwickian SD)

• Massive obesity
• reduced FRC
• Underventilation of Lung base and widening of
  (A-a)PO2
• Chronic hypercapnia, hypoxemia, polycythemia,
  pulmonary HTN, Right heart failure
• Sx OSA, sleep induced hypoventilation
• Tx stop smoking, weight reduction, correct OSA,
  medroxy progesterone