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Introduction to Vent Management

Jared Freitas

Ventilator Settings:

  • See above table in Modes of Oxygen Delivery for variables adjusted in each ventilator mode
  • Trigger: what initiates a breath; time, flow, or pressure (pt triggers are flow and pressure; ventilator breaths are trigged by time)

Static Ventilator Readouts:

  • Plateau pressure (Pplat): measure with inspiratory hold, assesses static lung compliance
  • Auto-PEEP: measure with expiratory hold; occurs when volume of previous breath is not entirely expelled before the next breath is initiated

Dynamic Ventilator Readouts:

  • Measured RR: in most modes, pt may trigger breaths above set RR; if set and measured RR match consider ↓ respiratory drive (sedation, neurologic injury) or iatrogenic over-ventilation
  • VTi / VTe: tidal volume of inspiration (VTi) and expiration (VTe)
    • VTi should approximately equal VTe, if not then concern for air leak (e.g. cuff leak or pneumothorax) or auto-PEEP
  • Minute ventilation: calculated from VTe x RR; higher MV = more CO2 clearance
  • Peak pressure: highest pressure reached in the entire ventilator cycle

Critical Non-ventilator hemodynamic readouts:

  • SpO2: if poor waveform or discordant with PaO2, may need serial ABG
  • HR: quickest indicator of emergencies such as pneumothorax, PE, ventilator disconnection
  • Blood pressure: positive pressure ventilation decreases preload and afterload; depending on the underlying pt physiology, increases in positive pressure may be detrimental or beneficial for BP
Alarm Type What is causing the alarm? Troubleshooting
High Peak Pressure Static compliance issue (stretch of the lung - doesn’t change with airflow) vs dynamic compliance issue (resistance of the circuit when there is air flowing)

Step 1: Check plateau pressure by performing inspiratory hold. Must be in VC mode.

High Peak and Low Plateau = Dynamic compliance issue -> High Resistance

  • Check circuit tubing for excess water condensation or a kink. Ask RT to disconnect and clear circuit
  • Check if pt is biting ETT
  • Incline suction to clear secretions or proximal mucous plug
  • Auscultate for wheezing/stridor to indicate bronchospasm or airway obstruction->give bronchodilators

High Peak and High Plateau = Static compliance issue -> Worsening alveolar process

  • Emergencies to quickly assess for:
    • Tension PTX
    • Main stem intubation (ask about any tube migration, listen to breath sounds, CXR)
  • Consider worsening alveolar process leading to decreased lung compliance: worsening pulmonary edema, PNA, DAH, ARDS or other non-alveolar process such as new pleural effusion, obesity, intraabdominal compartment syndrome
    • CXR, b-lines, tracheal aspirate, bronch, etc
    • Treat according to etiology (chest tube, reposition ETT, diuresis, abx, etc)
Low Tidal Volume/Low Minute Ventilation (VE) Pt is not getting the desired tidal volume/VE that was set in the vent parameters. The alarm reports exhaled VE. May cause inadequate ventilation, CO2 retention, potentially hypoxia

Compare inspiratory tidal volumes (Vti) with expiratory tidal volumes (Vte) on the ventilator. If Vti>Vte, check for a leak in the system

  • Have RT check all connections
  • Listen for a cuff leak – can have RT check a cuff pressure and if low then re-inflate->sometimes need to do an ETT exchange

If low tidal volumes and no leak (ie. Vti = Vte) and RR WNL

  • Pt may need more support, ie switching to a different vent mode (PS to PRVC). Discuss with RT or fellow

If low RR and no leak and Vt at goal

  • Pt may be oversedated
  • Ensure pt has a back-up rate in case they aren’t triggering the vent->may need to switch vent modes for this (i.e. take off pressure support) or increase set/ventilator respiratory rate
Apnea No breaths are being triggered by the vent - your pt is NOT breathing - this is an emergency

***Check that pt hasn’t self-extubated, trach hasn’t fallen out, or been unhooked from vent***

If self-extubated or tracheostomy decannulated, then immediately start bagging the pt (may need to bag from trach stoma if s/p laryngectomy). Have nurse call staff assist for re-intubation if necessary or have trach team called to replace a fresh (<7 days old) trach