LIBRO + ANEXOS NEUMOLOGÍA PEDIÁTRICA

Neumología Pediátrica. Anexos ❚ 221 f. Know the functional sequelae that may be associated with a highly compliant chest wall 5. Static mechanics of the combined lung & chest wall a. Know how the pressure-volume curve of the lung and that of the chest wall are combined to describe the mechanical characteristics of the respiratory system b. Know that end-expiratory volume in infants is actively determined c. Be able to calculate total respiratory system compliance 6. Pleural pressure a. Understand the relationships among pleural pressure, transpulmonary pressure, static alveolar pressure, and the pressure drop across the chest wall b. Know that intrapleural pressure in a patient who is at rest and breathing quietly is negative compared to atmospheric pressure throughout the breathing cycle c. Know how intrapleural pressure varies topographically within the thorax in a gravitational field d. Know that esophageal pressure approximates pleural pressure e. Know methods of measuring esophageal pressure f. Know that chest wall distortion, esophageal muscle contraction, and cardiac motion influence esophageal pressure independent of changes in pleural pressure B. Airway mechanics 1. Definitions a. Know the definitions of resistance and conductance b. Know the definitions and determinants of frequency dependence of resistance c. Understand how turbulent and laminar flow regimes influence airway resistance d. Understand how gas density and viscosity influence airway resistance during turbulent and laminar flow e. Understand the relationship between resistance and radius in a rigid tube under laminar flow conditions f. Know how resistance and compliance of a system determine the rate at which the system will empty passively (the time constant) g. Understand the functional significance of the expiratory time constant h. Know that increased flow rates can require a geometric increase in driving pressure under turbulent conditions (i.e., that resistance is not constant) i. Know that a helium-oxygen gas mixture can be used to reduce the work of breathing in airway obstruction where flow is highly turbulent (e.g., croup, tracheal narrowing) j. Know that a time constant of a lung region can be calculated as its resistance times it compliance k. Understand that lung regions with the shortest time constants fill first on inspiration and empty first on expiration and that they are generally the best ventilated lung regions l. Understand how pulmonary time constants impact optimal mechanical ventilator strategies in patients with obstructive or restrictive lung disease 2. Airway resistance/conductance a. Understand the relative contributions of the upper airway, central tracheobronchial tree, and peripheral airways to total airway resistance