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Table 3 Ventilatory conditions

From: High frequency oscillatory ventilation compared with conventional mechanical ventilation in adult respiratory distress syndrome: a randomized controlled trial [ISRCTN24242669]

 

HFOV

CV

Cross-over

No (30)

Yes (7)

No (20)

Yes (4)

Day 1

N = 28

N = 7 (7 HFOV)

N = 19

N = 4 (4 CV)

   Peak inspiratory pressure (cmH2O)

  

32 ± 4.2

35 ± 6.9

   Positive end-expiratory pressure (cmH2O)

  

14 ± 2.1

12 ± 4.5

   Mean airway pressure (cmH2O)

30 ± 5.6a

32 ± 6.3a

22 ± 3.2

22 ± 6.1

   Tidal volume per ideal bodyweight (ml/kg)

  

9 ± 1.7

8 ± 0.7

   Frequency (HFOV, Hz; CV, breaths/min)

5 ± 0.5

5 ± 0.9

17.3 ± 3

17.3 ± 6

   Delta P (cmH2O)

63 ± 14

70 ± 12.1

  

   FiO2

0.78 ± 0.19

0.82 ± 0.12

0.68 ± 0.12

0.78 ± 0.21

   pH

7.32 ± 0.08

7.31 ± 0.11

7.34 ± 0.08

7.22 ± 0.07b

   pCO2 (mmHg)

49 ± 11.3

57 ± 13

48 ± 9

52 ± 15.8

   pO2 (mmHg)

126 ± 79.2

93 ± 37.1

98 ± 26.6

99 ± 25

   SaO2 (percentage)

95 ± 3

90 ± 10.7

96 ± 2.4

94 ± 4.5

   Oxygenation index

26 ± 16

31 ± 8.3c

17 ± 7.5

19 ± 11.2c

Day 2

N = 27

N = 7 (6 HFOV)

N = 19

N = 4 (2 CV)

   Peak inspiratory pressure (cmH2O)

25 ± 6.7

36 ± 7.2

31 ± 4.5

30 ± 2.6

   Positive end-expiratory pressure (cmH2O)

11 ± 1.2

15 ± 1.9

14 ± 2.7

12 ± 4.7

   Mean airway pressure (cmH2O)

28 ± 6.7a

29 ± 4.3a

21 ± 2.3

22 ± 9.1

   Tidal volume per ideal bodyweight (ml/kg)

9 ± 1.6

10 ± 1.9

8 ± 1.6

8 ± 1

   Frequency (HFOV, Hz; CV, breaths/min)

5.0 ± 0.4

4.8 ± 1.1

17.4 ± 2.6

17.2 ± 1.2

   Delta P (cmH2O)

64 ± 14.5

73 ± 14.8

 

70 ± 13.8

   FiO2

0.55 ± 0.17

0.57 ± 0.14

0.53 ± 0.12

0.76 ± 0.20

   pH

7.36 ± 0.07

7.35 ± 0.04

7.38 ± 0.06

7.22 ± 0.08b

   pCO2 (mmHg)

45 ± 9

51 ± 8.9

46 ± 8.3

53 ± 8.5

   pO2 (mmHg)

96 ± 21

83 ± 12.4

100 ± 27

87 ± 41.8

   SaO2 (percentage)

95 ± 2.1

94 ± 1.9

96 ± 1.8

87 ± 16.1

   Oxygenation index

17 ± 10.2

21 ± 8.2c

12 ± 3.6

22 ± 10.5c

Day 3

N = 23

N = 7 (4 HFOV)

N = 19

N = 4 (2 CV)

   Peak inspiratory pressure (cmH2O)

21 ± 3.1

32 ± 12

30 ± 4

27 ± 6

   Positive end-expiratory pressure (cmH2O)

9 ± 3

10 ± 4.3

13 ± 2.8

11 ± 5.7

   Mean airway pressure (cmH2O)

23 ± 7.1a

25 ± 6.9a

20 ± 2.8

24 ± 2.3

   Tidal volume per ideal bodyweight (ml/kg)

9 ± 1.5

9 ± 3.5

9 ± 1.6

7 ± 1.6

   Frequency (HFOV, Hz; CV, breaths/min)

5.0 ± 0.4

4.6 ± 0.5

18.8 ± 6.5

19.9 ± 5.8

   Delta P (cmH2O)

66 ± 12.4

66 ± 19.1

 

67 ± 0.7

   FiO2

0.46 ± 0.13

0.55 ± 0.15

0.46 ± 0.11

0.65 ± 0.26

   pH

7.39 ± 0.06

7.37 ± 0.06

7.39 ± 0.06

7.33 ± 0.1b

   pCO2 (mmHg)

45 ± 10.4

47 ± 12.9

48 ± 9

47 ± 12.6

   pO2 (mmHg)

89 ± 19.7

86 ± 46.2

91 ± 13.7

89 ± 22.4

   SaO2 (percentage)

94 ± 6.7

89 ± 14.1

96 ± 1.9

95 ± 2.4

   Oxygenation index

14 ± 7.2

19 ± 9.3c

11 ± 3.7

20 ± 12.3c

Day 4

N = 22

N = 7 (3 HFOV)

N = 19

N = 2 (0 CV)

   Peak inspiratory pressure (cmH2O)

25 ± 8

31 ± 6.9

28 ± 6.9

 

   Positive end-expiratory pressure (cmH2O)

9 ± 4.6

11 ± 4.2

11 ± 3.2

 

   Mean airway pressure (cmH2O)

22 ± 7.8a

24 ± 6.2a

17 ± 5.6

24 ± 3.2

   Tidal volume per ideal bodyweight (ml/kg)

10 ± 2.4

7 ± 3.1

8 ± 2.2

 

   Frequency (HFOV, Hz; CV, breaths/min)

5.0 ± 0.3

4.3 ± 0.6

17.9 ± 5.3

 

   Delta P (cmH2O)

57 ± 11.4

70 ± 11.8

 

48 ± 14.8

   FiO2

0.45 ± 0.11

0.57 ± 0.18

0.45 ± 0.11

0.51 ± 0.12

   pH

7.42 ± 0.14

7.37 ± 0.1

7.43 ± 0.12

7.45 ± 0.06b

   pCO2 (mmHg)

43 ± 12.3

46 ± 7.5

41 ± 10.3

44 ± 11.1

   pO2 (mmHg)

85 ± 22.3

84 ± 30.5

87 ± 27.4

74 ± 23.7

   SaO2 (percentage)

89 ± 15.3

90 ± 14.1

89 ± 17.2

84 ± 20

   Oxygenation index

12 ± 5.6

18 ± 7.9c

10 ± 4.3

19 ± 9.5c

  1. The columns represent the treatment allocation. Measurements were made day 1, 2, 3 and 4 of the study. Peak inspiratory pressure, positive end-expiratory pressure and tidal volume per ideal bodyweight were measured in high frequency oscillatory ventilation (HFOV) after crossover to conventional mechanical ventilation (CV). Values are presented as means with standard deviations. aHigher mean airway pressures in HFOV compared with CV (p = 0.03). bSignificantly lower pH in patients that cross over in the CV group (p = 0.017). cHigher OI in patients that crossed over compared with patients that did not cross over (p = 0.07 and p = 0.05, respectively). FiO2, fraction of inspired oxygen; paCO2, pressure of arterial carbon dioxide; paO2, pressure of arterial oxygen; SaO2, arterial oxygen saturation.
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