The flow-time waveform predicts respiratory system resistance and compliance

Comparison of respiratory mechanics measurements in the volume cycled ventilation (VCV) and pressure controlled ventilation (PCV)

“…The results of this study, assessing 12 mechanically ventilated individuals, showed strong correlation between compliance and resistance measures in VCV and PCV modes (r 2 = 0.73 and r 2 = 0.51, respectively). In the same study (9), the mean values in the VCV mode were 36.93 ± 12.18 mL/cm H2O for compliance, and 12.50 ± 2.99 cmH2O/L/sec for resistance. However, the normal range is described with a wide range of variation, comprising 50 to 100 mL/cmH2O for compliance and between 2 and 5 cmH2O/L/sec for the respiratory system resistance (18).…”

“…The authors believe that this measure provides data on lung function and can describe the mechanics the motion equation and conversion of the nonlinear down flow to linear flow (9). The results of this study, assessing 12 mechanically ventilated individuals, showed strong correlation between compliance and resistance measures in VCV and PCV modes (r 2 = 0.73 and r 2 = 0.51, respectively).…”

“…This can be mostly related to the characteristics of the inspiratory flow in the two ventilation methods. While in the VCV mode flow is generally used in a square shape, practically constant, in the PCV mode it is variable with the shape resembling a triangle with an initial peak flow and almost linear fall (5,9). These aspects of air inlet in the respiratory system generate different pressure curves, which are closely related to the diffusivity of gases in the alveolar-capillary level.…”

See-saw pattern in ventilator graphic: Is there any story behind?

“…The importance of ventilator graphics is well described in the literature 1234. We can see various patterns in pressure-volume loop, which are the characteristic features of different airway conditions including obstructive, restrictive lung diseases, intra-operative kinking etc 1234.…”

“…In this regard, tracing the utility of ventilators is worth mentioning. The importance of ventilator graphics cannot be over emphasised, as they provide useful information about airway, ventilation, compliance, and lung mechanics 12345. Some bizarre forms of graphics are usually overlooked as artefacts, but sometimes these tracings may in fact predict some relevant information.…”