Crying Pressures Crying Transdiaphragmatic Pressure

Rationale. Crying transdiaphragmatic pressure (Pdi) measurements allow assessment of diaphragm muscle strength during inspiratory crying efforts in infants.

Measurements. Accurate recordings of Pes and gastric pressure (Pga) are essential.

Advantages. Transdiaphragmatic pressure is specific for diaphragmatic contraction.

Disadvantages. Disadvantages include (1) the fact that reliability of Pdi requires accurate measurements of Pes; and (2) similar limitations to crying Pi,max with respect to variability in lung volume at which Pdi is measured during crying efforts.

TABLE 2. NORMAL VALUES OF MAXIMAL INSPIRATORY AND EXPIRATORY PRESSURES IN HEALTHY CHILDREN AND ADOLESCENTS

TABLE 2. NORMAL VALUES OF MAXIMAL INSPIRATORY AND EXPIRATORY PRESSURES IN HEALTHY CHILDREN AND ADOLESCENTS

Reference

(yr)

At RV

At FRC

At TLC

At FRC

Males

47

8

79

13

77

±

24

70 ± 24

99 ± 23

83 ± 16

47

10

90

13

105

±

27

97 ± 22

123 ± 27

100 ± 23

47

11-13

90-101*

13

114

±

27

105 ± 23

161 ± 37

132 ± 33

41*

130

±

16

176 ± 24

46

13-17

111

±

34

131 ± 30

47

107-129*

42

107

±

26

114 ± 35

41 +

126

±

22

166 ± 44

Females

47

8

62

13

71

±

29

59 ± 21

74 ± 25

65 ± 18

47

10

90

13

71

±

29

59 ± 21

74 ± 25

65 ± 18

47

11-13

77-86*

13

108

±

29

98 ± 25

126 ± 32

101 ± 26

41*

112

±

20

138 ± 31

46

13-17

85

±

28

95 ± 29

47

86-107

42

76

±

25

86 ± 22

41 +

109

±

21

135 ± 29

Definition of abbreviations: FRC = functional residual capacity; PE,max = maximum expiratory pressure; Pi,max = maximum inspiratory pressure; RV = residual volume; TLC = total lung capacity.

* Cylindric mouthpiece.

Definition of abbreviations: FRC = functional residual capacity; PE,max = maximum expiratory pressure; Pi,max = maximum inspiratory pressure; RV = residual volume; TLC = total lung capacity.

* Cylindric mouthpiece.

Normal values. Transdiaphragmatic pressure during crying efforts has been measured in 18 healthy infants from 8 to 21 months postconceptional age, i.e., gestational age plus postnatal age (60). Crying Pdi is ~ 60 cm H2O at 1 month postnatal age, which is much lower than reported crying Pi,max (14). Crying Pdi increases with postconceptional age (60).

Clinical application. Crying Pdi may be useful in infants with abdominal wall defects or after repair of diaphragmatic hernia (60).

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