Multiprofessional Critical Care Review: Pediatric 2024 (MCCRCP24ON)-Mech Ventilation and CRI

Mech Ventilation and CRI

Pdf Summary

Dr. Ira M Cheifetz discusses mechanical ventilation, focusing on the optimal use of various modes and their physiological implications. The presentation covers a range of ventilation modes (e.g., NAVA, PAV, APRV, SIMV, CPAP) and emphasizes the importance of understanding how to use available modes effectively rather than having access to every mode. It notes that definitive outcome data proving the superiority of one mode over another are lacking, so the choice should match the patient's pathophysiology.<br /><br />Key concepts in defining ventilator breaths include the type of breath (mode), quantity of gas flow (limit), factors initiating the breath (trigger), end of inspiratory flow (cycle), and inspiratory flow pattern. Modes can be categorized into control (all mechanical breaths), support (all spontaneous breaths), and mixed (e.g., SIMV).<br /><br />Question points in the presentation address the definition of a spontaneous breath and the concept of elastance (pressure/volume). Respiratory mechanics, such as compliance (volume/pressure), elastance, and resistance (pressure/flow), are crucial for understanding mechanical ventilation. The concept of the time constant (TC), borrowed from electrical engineering, explains the time required for a given percentage of a passively exhaled breath to be exhaled, dependent on lung compliance and airway resistance.<br /><br />The talk also covers deadspace, differentiating between physiological and anatomical deadspace, and the ventilation-perfusion ratio. Cardiorespiratory interactions outline the determinants of oxygen delivery and consumption, emphasizing the importance of optimizing cardiac output and pulmonary function.<br /><br />The presentation concludes with the effects of positive pressure ventilation (PPV) on right and left ventricular function, noting that while PPV can reduce right ventricular preload and potentially increase pulmonary vascular resistance, it generally supports left ventricular afterload. The importance of understanding mechanical breaths, basic equations, and the time constant is emphasized, along with the insight that mechanical ventilation typically favors the left ventricle over the right.

Keywords

mechanical ventilation

ventilation modes

NAVA

PAV

APRV

SIMV

CPAP

respiratory mechanics

positive pressure ventilation

cardiorespiratory interactions

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