Description
Mechanical ventilation is an important strategy for sustaining life in acute or emergent settings, especially in patients with damaged airways, poor breathing, or hypoxic respiratory failure. This treatment uses positive pressure breaths and relies on the airway system's compliance and resistance. Clinicians in critical care units must grasp how mechanical ventilation influences patient physiology and reaction to diverse disease states, highlighting the importance of a thorough understanding of safe use guidelines. A thorough understanding of human physiology and airway mechanics concepts is essential for clinicians treating intubated patients, laying the groundwork for safe and effective breathing techniques. This understanding is critical for recognizing key indications for invasive mechanical ventilation, such as airway compromise, protection in obtunded individuals or those with dynamic airways.
Summary Listen
- The lecture focuses on simplifying ventilator basics for those unfamiliar with their operation, avoiding complex terminology like trigger flow and cycling. The main goal of mechanical ventilation is to control oxygenation and remove CO2 (ventilation). The type of patient's physiology is a key consideration, categorizing them into COPD, ARDS/restrictive lung disease, or metabolic acidosis.
- Mechanical ventilators deliver three types of breaths: controlled, assisted, and supported. Controlled breaths are fully managed by the ventilator, while assisted breaths are triggered by patient effort. Supported breaths involve patient effort with ventilator assistance. Basic settings to adjust on the ventilator include tidal volume, respiratory rate, FiO2 (fraction of inspired oxygen), PEEP (positive end-expiratory pressure), and inspiratory flow rate.
- Tidal volume should be set between 6-8 ml/kg of ideal body weight for lung protection, not ventilation. Respiratory rate is adjusted based on the required minute ventilation, usually aiming for 60-80 ml/kg per minute plus additional space ventilation. Inspiratory flow rate should be set relatively high to allow adequate expiratory time. Initial FiO2 is set to 100%, then reduced to maintain SPO2 between 88-95%, adjusting PEEP according to the ARDS net protocol.
- Plateau pressure, monitored using an inspiratory hold, should be kept below 30 to prevent barotrauma. If plateau pressures are too high, reduce the tidal volume. In severe metabolic acidosis, a higher minute ventilation is needed to compensate, which can be determined using Winter's equation.
- For obstructive patients like COPD, the goal is to increase expiratory time. Set tidal volume at 8 ml/kg, inspiratory flow rate high (80-100 L/min), PEEP between 3-5, respiratory rate low, and IE ratio high (1:4 or 1:5). Permissive hypercapnea is acceptable, targeting a pH above 7.1. Air trapping is a significant concern, and the flow-time graph should be monitored.
- In ARDS patients, the goal is to maintain alveoli open with PEEP to reduce shear forces. Tidal volume should be kept at 6 ml/kg or less. PRVC (Pressure Regulated Volume Control) is an advanced mode delivering set tidal volume with the lowest possible pressures. SIMV (Synchronized Intermittent Mandatory Ventilation) with pressure support allows controlled, assisted, and supported breaths.
- The key takeaway is to become comfortable with one or two modes and learn them well, tailoring settings to the patient's physiology. In severe metabolic acidosis, use higher minute ventilation; in obstructive patients, lower rate and volume mode; and in ARDS, higher PEEP and lower tidal volume.
Sample Certificate
About the Speakers
Dr. Anurag Aggarwal
Director and HOD - Emergency Medicine and Trauma, Fortis Hospital, Noida
Financial Disclosure
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