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Table 3 Physiological measurements under PSV and PAV+ 

From: Refractory ineffective triggering during pressure support ventilation: effect of proportional assist ventilation with load-adjustable gain factors

 

PSV

PAV+

Δ (PAV+ – PSV)

p

SpO2, %

96 [93–97]

96 [94–98]

− 1 [− 1–0]

0.629

PaO2/FiO2, mm Hg

228 [209–257]

213 [203–298]

− 14 [− 28–60]

0.820

PaCO2, mm Hg

36 [33–41]

45 [34–55]

8 [1–12]

0.032

Heart rate, /min

103 [89–109]

101 [96–108]

2 [− 1–8]

0.181

MAP, mm Hg

89 [79–94]

92 [88–98]

5 [0–12]

0.032

Lactate, mmol/L

1 [0.9–1.1]

0.9 [0.8–1]

− 0.1 [− 0.2–0]

0.611

Inspiratory delay, ms

230 [200–290]

240 [180–290]

− 30 [− 43–9]

0.289

Ventilator insufflation time, s

1 [0.9–1.2]

0.8 [0.7–1.2]

− 0.1 [− 0.3–0.2]

0.519

Tidal volume

    

 mL

385 [322–485]

332 [237–398]

− 71 [− 176–2]

0.052

 mL/kg of PBW

6.5 [5.5–8.2]

5.6 [4.1–7.2]

− 1.0 [− 3.0–0.0]

0.045

Respiratory rate

    

 Ventilator, breaths/min

26 [22–27]

35 [29–40]

7 [3–14]

0.007

 Patient, breaths/min

41 [28–46]

39 [30–43]

− 2 [− 4–1]

0.264

Minute ventilation, L/min

9.1 [8.3–11.8]

11 [8.8–12.5]

0.7 [− 1.9–2.1]

0.791

Ventilatory ratio*

2.1 [1.41–2.3]

1.74 [1.29–2.65]

0.1 [− 0.1–0.5]

.0515

Pmuspeak, cmH2O

9.1 [4.7–11.4]

11.6 [9.6–13.2]

3.1 [− 0.1–5.7]

0.06

Total PTPes, cmH2O/s/min

107 [79–131]

149 [129–170]

43 [1–89]

0.092

Effective PTPes, cmH2O/s/min

84 [70–104]

135 [127–161]

54 [20–84]

0.016

Ineffective PTPes, cmH2O/s/min

8 [3–30]

2 [1–6]

− 8 [− 28–− 2]

0.012

Intrinsic PEEP, cmH2O

3.9 [3–4.1]

5.6 [2.1–7.2]

0.5 [− 1.3–2.5]

0.380

  1. PSV: Pressure support ventilation with the lowest tolerated pressure support level; PAV+: proportional assist ventilation with load-adjustable gain factors with the gain adjusted to target a peak muscle pressure between 5 and 10 cmH2O; the Δ (PAV+-PSV) column represents the median [interquartile range] of individual differences between PAV+ and PSV. MAP: mean arterial pressure; PBW: predicted body weight; Pmuspeak: peak muscle pressure; PTPes: esophageal pressure–time product; PEEP: positive end-expiratory pressure. Note that intrinsic PEEP was measured as the drop in esophageal pressure before increase in flow, which could also capture expiratory muscles relaxation. Effective PTPes denotes PTPes recorded during respiratory efforts that effectively trigger an insufflation from the ventilator; ineffective PTPes denotes PTPes recorded during ineffective triggerings. * Ventilatory ratio is defined as (minute ventilation × PaCO2)/((predicted body weight/10) × 37.5))