respiratory disease

Diseases of the mammalian Respiratory system are classified physiologically into obstructive (i.e. conditions which impede the rate of flow into and out of the lungs) and restrictive (i.e. conditions which cause a reduction in the functional volume of the lungs).

Anatomically, respiratory disease can be classified into these categories; upper and lower respiratory tract (most commonly used in the context of infectious respiratory disease), parenchymal and vascular lung diseases.

Obstructive lung disease

• Emphysema
• Bronchitis
• Asthma
• Chronic obstructive pulmonary disease (COPD)
• Bronchiectasis
• Byssinosis
• Bronchiolitis
• Asbestosis

Obstructive disease is characterized by an increase in airway resistance that is measured as a decrease in peak expiratory flow rates. In some cases, there is a miss-match between the FEV1/FVC ratio. The normal person exhales most of the inspired air in the 1st second; this ratio on normal subjects is around 0.8, this means that 80% of the expired air is expelled the 1st second.

Restrictive lung diseases

• Fibrosis
• Sarcoidosis
• Alveolar Damage
• Pleural effusion
• Hypersensitivity pneumonitis
• Asbestosis
• Pleurisy
• Lung Cancer

This pattern is characterized by an increase of the force trying to collapse the lung (recoil) and a decrease in lung compliance, measured as a decrease in all lung volumes. This is opposed to Obstructive in which you only have an increment of the values that take in to notice Residual Volumes (RV) such as TLC (Total Lung Capacity) and FRC (Functional Residual Capacity). In this case TLC is smaller than normal since the recoil force in the lung is greater than what it should be, the FEV1/FVC ratio will also be altered but instead of being lower than normal it will be higher than normal.

As previously stated FEV1/FVC should be around 0.8, in Obstructive Disease is lower, in Restrictive Disease since the amount of air going in is a lot less than in a normal or an obstructive pattern, the ratio appears to be higher (more than 80%) this is because a the smaller volume is expired quickly and more completely than in a normal pattern

Infectious lung disease

• Upper respiratory tract infections
• Lower respiratory tract infections or Pneumonia
• Tuberculosis

Vascular lung disease

• Pulmonary edema
• Pulmonary embolism
• Pulmonary hypertension

Respiratory tumors

• Lung Cancer

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