Question

In measuring pulmonary airway resistance, what does the unit Rn (cmH20.s/ml) mean. Explain in details

Answer 1

airway resistance is the resistance of the respiratory tract to airflow during inhalation and expiration. caused by the forces of friction. It is defined as the ratio of driving pressure to the rate of air flow. Resistance to flow in the airways depends on whether the flow is laminar or turbulent, on the dimensions of the airway, and on the viscosity of the gas. The main determinants of airway resistance are the size of the airway and the properties of the flow of air itself.
Airway resistance can be measured using body plethysmography.
Transpulmonary pressure is the pressure gradient between the inside alveolar pressure and outside pleural pressure. It mainly measures the force of lung elasticity at each point of respiration. Alveolar pressure is the air pressure inside the alveoli. Pleural pressure is the pressure of the fluid present inside the space between visceral pleura (layer adhered to lungs) and parietal pleura (chest wall lining layer). Normally the total compliance of both lungs in an adult is about 200 ml/ cm H2O. Physicians rely on this concept to understand some pulmonary pathologies and help to guide therapy and adjust ventilator pressure and volume settings.