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Figure 3 | Critical Care

Figure 3

From: Assessment of patient-ventilator breath contribution during neurally adjusted ventilatory assist in patients with acute respiratory failure

Figure 3

Impact of breath averaging and breath matching on coefficient of determination between patient-ventilator breath contribution indices and ratio of inspiratory changes in esophageal pressure and transpulmonary pressure.Left: Coefficient of determination (R2) between patient-ventilator breath contribution (PVBC) and ratio of inspiratory changes in esophageal pressure and transpulmonary pressure (ΔPes/ΔPtp) (y-axis) is plotted against different matching criteria of increasingly strict inclusion levels (x-axis). Data are presented for PVBC indices when PVBC is calculated with one assisted breath (N1PVBC, open symbols) or with five assisted breaths averaged (X5PVBC, closed symbols). The determination coefficient was found to improve for X5PVBC at matching levels for ratios of inspiratory peak electrical activity of the diaphragm (EAdipk) with versus without assist (EAdipk,no-assist/EAdipk,assist) ranging from 0.77 to 1.30 ($P <0.05, orange closed symbols) and to become significantly higher than N1PVBC (*P <0.05). Increasing the matching of the neural inspiratory time (Ti) between assisted and non-assisted breaths (Tino-assist/Tiassist, blue symbols) did not result in any improvement in R2. Values are presented as mean with 95% confidence interval. Right: Same as left graph, but for PVBC2. The R2-value between PVBC2 and ΔPes/ΔPtp (y-axis) is plotted when PVBC2 is calculated with one assisted breath (N1PVBC2, open symbols) or with five assisted breaths averaged (X5PVBC2, closed symbols) and when different matching criteria are used of increasingly strict inclusion levels (x-axis). The determination coefficient was found to improve for X5PVBC2 at matching levels for EAdipk,no-assist/EAdipk,assist of 0.77 to 1.30 ($P <0.05, *P <0.05, orange closed symbols) and to become significantly higher than N1PVBC2 (*P <0.05). Increasing the matching of the Ti between assisted and non-assisted breaths (Tino-assist/Tiassist, blue symbols) did not result in any improvement in R2. Values are presented as mean with 95% confidence interval.

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