Research ArticleConference Proceedings

Ventilator Graphics: Scalars, Loops, & Secondary Measures

Amanda M Dexter and Kimberly Clark
Respiratory Care June 2020, 65 (6) 739-759; DOI: https://doi.org/10.4187/respcare.07805

Article Figures & Data

Figures

  • Fig. 1.
    Fig. 1.

    Single-compartment model of the respiratory system. From Reference 9.

  • Fig. 2.
    Fig. 2.

    Mechanical ventilation mathematical interpretations. (A) Volume control continuous mandatory ventilation. (B) Fixed settings and affected changes during volume control continuous mandatory ventilation; changes in respiratory mechanics affect the pressure scalar. (C) Pressure control continuous mandatory ventilation. (D) Fixed settings and affected changes during pressure control continuous mandatory ventilation; changes in respiratory mechanics affect the volume and flow scalars. (E) Scalar distortion or patient–ventilator asynchrony in volume control continuous mandatory ventilation. Pvent = ventilation pressure; E = respiratory system elastance; V = volume; R = airway resistance; Embedded Image = flow over time.

  • Fig. 3.
    Fig. 3.

    Flow-time scalar showing air trapping. From Reference 37.

  • Fig. 4.
    Fig. 4.

    Ventilator scalars indicating a leak. From Reference 38.

  • Fig. 5.
    Fig. 5.

    Pressure-time scalar displaying increased transairway pressure, which is the difference between peak inspiratory pressure (PIP) and plateau pressure (Pplat).

  • Fig. 6.
    Fig. 6.

    Pressure-time scalars presenting various stress indices: minimal stress (stress index = 1) indicates optimum (normal) ventilation; high-volume stress (stress index > 1) specifies alveolar overdistention; low-volume stress (stress index < 1) shows continuing recruitment. From Reference 47.

  • Fig. 7.
    Fig. 7.

    Visual inspection of pressure-time scalar and stress index into 3 categories: a linear shape indicating optimum ventilation, a downward concavity showing alveolar overdistention, and an upward convexity denoting continued recruitment. Paw = airway pressure. From Reference 56.

  • Fig. 8.
    Fig. 8.

    VC-CMV ventilator graphics monitoring decreased lung compliance; there is no change in transairway pressure (i.e. PIP-Pplateau) (PPEAK = peak inspiratory pressure, PPL = plateau pressure) (red circles) and the peak expiratory flow rate increased (V= flow rate over time) (red arrows)

  • Fig. 9.
    Fig. 9.

    VC-CMV ventilator graphics monitoring increased airway resistance; the larger the airway resistance, the larger the difference in the transairway pressure (i.e. PIP-Pplateau) (PPEAK = peak inspiratory pressure, PPL = plateau pressure) (red circles). Also, as airway resistance increases, the peak expiratory flow rate decreases (V= flow rate over time) (red arrows)

  • Fig. 10.
    Fig. 10.

    Flow-time graphic variations of increased airway resistance and decreased compliance during pressure control continuous mandatory ventilation. From Reference 47.

  • Fig. 11.
    Fig. 11.

    An air leak on a flow-volume plot (lower panel). From Reference 38.

  • Fig. 12.
    Fig. 12.

    A flow-volume plot showing increased airway resistance. From Reference 37.

  • Fig. 13.
    Fig. 13.

    A pressure-volume plot indicating increased patient effort or work of breathing. From Reference 37.

  • Fig. 14.
    Fig. 14.

    A flow-volume (F/V) plot identifying air trapping. From Reference 37.

  • Fig. 15.
    Fig. 15.

    Ventilator scalars illustrating excessive triggering threshold, which causes increased word of breathing. Esophageal pressure waveforms pick up ineffective efforts during inspiration and expiration. From Reference 37.

Tables

  • Table 1.
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