PHTY300 Lecture Notes - Lecture 2: Pulmonary Edema, Kyphoscoliosis, The New England Journal Of Medicine
Document Summary
Week 2: non-invasive ventilation and acute respiratory failure. Increasingly used in managing hypoxemia rather than cpap (continuous positive airway pressure) Evidence still limited (frat, n engl j med 2015; stephan, jama 2015) More reliably reduces eti than niv (ni, chest 2017) Aims to deliver adequately heated and humidified gas at flow rates up to 60l/min. Physiological effects: good humidification preserves mucociliary function, anatomical deadspace co2 washout, high nasal inspiratory flow, small amount of peep - lung volumes or recruit collapsed alveoli, constant fraction of inspired oxygen. Cpap: delivery of a constant single level of pressure during both inspiration and expiration. Provides a distending pressure, increases pressure within the airway or alveoli. Primarily used for hypoxemia: acute cardiogenic pulmonary oedema or obstructive sleep apnea. Risk of over inflation and alveolar dead space. To improve gas exchange - paco2 and correct acidosis. Reduce the work of breathing relieve dyspnoea. Goals: prevent the need for invasive ventilation.
