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Table 2 Main results of the study

From: Gas conditioning during helmet noninvasive ventilation: effect on comfort, gas exchange, inspiratory effort, transpulmonary pressure and patient–ventilator interaction

 

NoH

HME

HH34

HH37

p

Gas exchange

 PaO2/FiO2 ratio, mmHg

260 [216–320]

252 [207–317]

232 [188–303]

234 [201–292]

0.73

 PaCO2, mmHg

30 [28–36]

34 [30–37]

31 [29–35]

34 [29–38]

0.46

 pH

7.47 [7.42–7.49]

7.44 [7.41–7.48]

7.46 [7.42–7.49]

7.47 [7.41–7.49]

0.73

Gas conditioning, self-assessed symptoms and fog effect

 Absolute humidity, mgH2O/L

16 [12–19]αβγ

28 [23–31]αε

28 [24–31]βζ

33 [29–38]γζ

 < 0.001

 Relative humidity, %

52 [40–63]αβγ

92 [81–97]αε

96 [83–100]β

100 [93–100]γε

 < 0.001

 Helmet temperature, °C

29 [28–30]α

30 [29–31]ε

31 [29–32]ζ

32 [31–33]αεζ

 < 0.001

 Dyspnea, VAS

2 [1–5]

3 [1–5]

4 [1–5]

4 [1–7]

0.46

 Discomfort, VAS

4 [2–6]γ

6 [2–7]

7 [4–8]

8 [4–10]γ

0.03

 Fog effect, 1–3 scale

0 [0–0]αβγ

1 [1–3]αε

2 [1–3]βζ

3 [3–3]γζ

 < 0.001

Respiratory mechanics and work of breathing indices

 Patient respiratory rate, bpm

26 [22–31]

26 [22–32]

27 [21–33]

26 [22–31]

0.99

 Ventilator respiratory rate, bpm

31 [27–36]

31 [25–34]

32 [24–34]

30 [23–33]

0.43

 Helmet minute ventilation, L*min−1

21 [20–27]

19 [16–24]δε

27 [23–30]δ

24 [20–32]ε

0.009

 ΔPES, cmH2O

7 [4–9]

9 [5–11]

6 [4–10]

7 [5–11]

0.54

 ΔPL, cmH2O

21 [17–23]

17 [15–21]

20 [18–23]

21 [16–24]

0.21

 PTPES per minute, cmH2O*sec*min−1

82 [40–127]

109 [32–172]

74 [34–137]

61 [39–112]

0.74

Patient–ventilator asynchronies

 Asynchrony index (AI), %

19 [4–51]

7 [2–33]

18 [5–35]

16 [4–40]

0.78

 Ineffective efforts, %

1 [0–2]

1 [0–2]

1 [0–5]

2 [0–6]

0.55

 Proportion of AI due to ineffective efforts, %

14 [0–71]

15 [0–63]

19 [0–64]

22 [0–61]

0.99

 Double cycling, %

1 [0–5]α

0 [0–1]αε

0 [0–3]

1 [0–3]ε

0.05

 Proportion of AI due to double cycling, %

7 [0–30]α

0 [0–7]αε

0.3 [0–12]

11 [0–26]ε

0.07

 Premature expiratory cycling, %

7 [1–40]

2 [0–19]

6 [0–16]

4 [0–14]

0.72

 Proportion of AI due to premature expiratory cycling, %

42 [9–80]

24 [0–74]

22 [6–56]

21 [13–56]

0.66

 Autotriggering, %

0 [0–1]βγ

0 [0–2]δ

1 [0–8]βδ

1 [0–6]γ

0.03

 Proportion of AI due to autotriggering, %

0 [0–2]βγ

2 [0–30]

14 [2–28]β

16 [3–39]γ

0.01

Hemodynamics

 Heart rate, bpm

83 [80–109]

90 [75–108]

90 [75–108]

90 [76–106]

0.98

 Mean arterial pressure, mmHg

87 [73–104]

88 [78–106]

88 [72–101]

83 [74–103]

0.61

  1. Data are expressed as median [interquartile range]
  2. α indicates a p < 0.05 for paired comparisons between NoH and HME
  3. β indicates a p < 0.05 for paired comparisons between NoH and HH34
  4. γ indicates a p < 0.05 for paired comparisons between NoH and HH37
  5. δ indicates a p < 0.05 for paired comparisons between HME and HH34
  6. ε indicates a p < 0.05 for paired comparisons between HME and HH37
  7. ζ indicates a p < 0.05 for paired comparisons between HH34 and HH37