Int J Clin Pediatr

International Journal of Clinical Pediatrics, ISSN 1927-1255 print, 1927-1263 online, Open Access

Article copyright, the authors; Journal compilation copyright, Int J Clin Pediatr and Elmer Press Inc

Journal website https://www.theijcp.org

Original Article

Volume 12, Number 2, September 2023, pages 37-44

Are the Reference Equations for Maximal Respiratory Pressure in Children Adequately Predicting Their Value?

Figure 1. Measured and predicted maximal respiratory pressure values for each equation described [9-11, 13-15].

**Table 1.** Reference Equations for Respiratory Muscle Strength
Author (n), country		Age (years)	Equation	R²
^aSex male = 1, female = 0. ^bSex male = 1; female = 2; age: years old; weight in kg; height in centimeter. ^cHeight in meter. MIP: maximal inspiratory pressure; MEP: maximal expiratory pressure.
Heinzmann et al [11] (n = 171), Brazil	MIP, male	4 - 12	17.879 - (0.674 × height) - (0.604 × weight)	0.58
	MIP, female	4 - 12	14.226 - (0.551 × height) - (0.638 × weight)	0.58
	MEP, male	4 - 12	47.417 + (0.898 × weight) + (3.166 × age)	0.46
	MEP female	4 - 12	30.045 + (0.749 × weight) + (4.213 × age)	0.51
Mendes et al [13] (n = 182), Brazil	MIP	12 - 18	53.8 + (26.1 × sex) + (0.4 × weight)	0.27
	MEP	12 -18	86.85 + (34.22 × sex)	0.27
Lanza et al [9] (n = 450), Brazil	MIP	6 - 11	37.458 - 0.559 + (age × 3.253) + (BMI × 0.843) + (age × sex^a × 0.985)	0.34
	MEP	6 - 11	38.556 + 15.892 + (age × 3.023) + (BMI × 0.579) + (age × sex^a × 0.881)	0.31
	MIP	12 - 18	92.472 + (sex^a × 9.894) + 7.103	0.27
	MEP	12 - 18	68.113 + (sex^a × 17.022) + 6.46 + (BMI × 0.927)	0.34
Domenech-Clar et al [10] (n = 392), Spain	MIP, male	8 - 17	-27.020 - (4.132 × age) - (0.003 × height × weight)	0.40
	MIP, female	8 - 17	-33.854 - (1.814 × age) - (0.004 × height × weight)	0.21
	MEP, male	8 - 17	7.619 + (7.806 × age) + (0.004 × height × weight)	0.51
	MEP, female	8 - 17	17.066 + (7.22 × age)	0.28
Wilson et al [14] (n = 235), United Kingdom	MIP, male	7 - 17	44.5 + (0.75 × weight)	0.16
	MEP, male	7 - 17	35 + (5.5 × age)	0.35
	MIP, female	7 - 17	40 + (0.57 × weight)	0.11
	MEP, female	7 - 17	24 + (4.8 × age)	0.34
Gaultier et al [15] (n = 119), Canada	MIP	7 - 13	-92.68 - (11.56 × sex^b) + (15.00 × height^c)	0.27
	MEP	7 - 13	-11.32 + (14.22 × age) - (25.7 × sex^b)	0.33

Table 1. Reference Equations for Respiratory Muscle Strength

Author (n), country

Age (years)

Equation

R²

^aSex male = 1, female = 0. ^bSex male = 1; female = 2; age: years old; weight in kg; height in centimeter. ^cHeight in meter. MIP: maximal inspiratory pressure; MEP: maximal expiratory pressure.

Heinzmann et al [11] (n = 171), Brazil

MIP, male

4 - 12

17.879 - (0.674 × height) - (0.604 × weight)

0.58

MIP, female

4 - 12

14.226 - (0.551 × height) - (0.638 × weight)

0.58

MEP, male

4 - 12

47.417 + (0.898 × weight) + (3.166 × age)

0.46

MEP female

4 - 12

30.045 + (0.749 × weight) + (4.213 × age)

0.51

Mendes et al [13] (n = 182), Brazil

MIP

12 - 18

53.8 + (26.1 × sex) + (0.4 × weight)

0.27

MEP

12 -18

86.85 + (34.22 × sex)

0.27

Lanza et al [9] (n = 450), Brazil

MIP

6 - 11

37.458 - 0.559 + (age × 3.253) + (BMI × 0.843) + (age × sex^a × 0.985)

0.34

MEP

6 - 11

38.556 + 15.892 + (age × 3.023) + (BMI × 0.579) + (age × sex^a × 0.881)

0.31

MIP

12 - 18

92.472 + (sex^a × 9.894) + 7.103

0.27

MEP

12 - 18

68.113 + (sex^a × 17.022) + 6.46 + (BMI × 0.927)

0.34

Domenech-Clar et al [10] (n = 392), Spain

MIP, male

8 - 17

-27.020 - (4.132 × age) - (0.003 × height × weight)

0.40

MIP, female

8 - 17

-33.854 - (1.814 × age) - (0.004 × height × weight)

0.21

MEP, male

8 - 17

7.619 + (7.806 × age) + (0.004 × height × weight)

0.51

MEP, female

8 - 17

17.066 + (7.22 × age)

0.28

Wilson et al [14] (n = 235), United Kingdom

MIP, male

7 - 17

44.5 + (0.75 × weight)

0.16

MEP, male

7 - 17

35 + (5.5 × age)

0.35

MIP, female

7 - 17

40 + (0.57 × weight)

0.11

MEP, female

7 - 17

24 + (4.8 × age)

0.34

Gaultier et al [15] (n = 119), Canada

MIP

7 - 13

-92.68 - (11.56 × sex^b) + (15.00 × height^c)

0.27

MEP

7 - 13

-11.32 + (14.22 × age) - (25.7 × sex^b)

0.33

**Table 2.** Comparison Between Measured Respiratory Muscle Strength and Gaultier et al (7 - 13 Years Old), Heinzmann et al (4 - 12 Years Old) and Lanza et al (6 - 11 Years Old) Predicted Equations
	Respiratory muscle strength	Mean difference between measured and predicted values (95% CI)	P	ICC (95% CI)	P
MIP: maximal inspiratory pressure; MEP: maximal expiratory pressure; CI: confidence interval; ICC: intraclass correlation coefficient.
MIP, cm H₂O
Measured (n = 64)	80 ± 22	-	-	-	-
Predicted by Gaultier et al [15]	90 ± 6	-9 (-18 to -1)	0.013	-0.3 (-1.1 - 0.1)	0.94
Predicted by Heinzmann et al [11]	90 ± 15	-10 (-17 to -3)	0.002	0.6 (0.3 - 0.7)	< 0.001
Predicted by Lanza et al [9]	86 ± 8	-6 (-13 to - 1)	0.129	0.5 (0.1 - 0.6)	0.004
MEP, cm H₂O
Measured (n = 64)	84 ± 21	-	-	-	-
Predicted by Gaultier et al [15]	76 ± 25	8 (0 - 15)	0.036	-0.6 (0.4 - 0.8)	< 0.001
Predicted by Heinzmann et al [11]	101 ± 15	-17 (-23 to -10)	< 0.001	0.5 (-0.1 - 0.7)	< 0.001
Predicted by Lanza et al [9]	96 ± 7	-12 (-18 to -6)	< 0.001	0.4 (0.1 - 0.7)	0.001

Table 2. Comparison Between Measured Respiratory Muscle Strength and Gaultier et al (7 - 13 Years Old), Heinzmann et al (4 - 12 Years Old) and Lanza et al (6 - 11 Years Old) Predicted Equations

Respiratory muscle strength

Mean difference between measured and predicted values (95% CI)

ICC (95% CI)

MIP: maximal inspiratory pressure; MEP: maximal expiratory pressure; CI: confidence interval; ICC: intraclass correlation coefficient.

MIP, cm H₂O

Measured (n = 64)

80 ± 22

Predicted by Gaultier et al [15]

90 ± 6

-9 (-18 to -1)

0.013

-0.3 (-1.1 - 0.1)

0.94

Predicted by Heinzmann et al [11]

90 ± 15

-10 (-17 to -3)

0.002

0.6 (0.3 - 0.7)

< 0.001

Predicted by Lanza et al [9]

86 ± 8

-6 (-13 to - 1)

0.129

0.5 (0.1 - 0.6)

0.004

MEP, cm H₂O

Measured (n = 64)

84 ± 21

Predicted by Gaultier et al [15]

76 ± 25

8 (0 - 15)

0.036

-0.6 (0.4 - 0.8)

< 0.001

Predicted by Heinzmann et al [11]

101 ± 15

-17 (-23 to -10)

< 0.001

0.5 (-0.1 - 0.7)

< 0.001

Predicted by Lanza et al [9]

96 ± 7

-12 (-18 to -6)

< 0.001

0.4 (0.1 - 0.7)

0.001

**Table 3.** Comparison Between Measured Respiratory Muscle Strength and Lanza et al (12 - 18 Years Old) and Mendes et al (12 - 18 Years Old) Predicted Equations
	Respiratory muscle strength	Mean difference between measured and predicted values (95% CI)	P	ICC (95% CI)	P
MIP: maximal inspiratory pressure; MEP: maximal expiratory pressure; CI: confidence interval; ICC: intraclass correlation coefficient.
MIP, cm H₂O
Measured (n = 100)	96 ± 28	-	-	-	-
Predicted by Lanza et al [9]	105 ± 5	-10 (-16 to -3)	0.002	0.2 (-0.1 - 0.5)	0.108
Predicted by Mendes et al [13]	92 ± 15	4 (-3 - 10)	0.466	0.5 (0.2 - 0.6)	0.001
MEP, cm H₂O
Measured (n = 100)	98 ± 24	-	-	-	-
Predicted by Lanza et al [9]	104 ± 9	-6 (-11 - 1)	0.013	0.4 (0.2 - 0.6)	0.001
Predicted by Mendes et al [13]	106 ± 17	-8 (-14 to -3)	0.001	0.6 (0.4 - 0.7)	< 0.001

Table 3. Comparison Between Measured Respiratory Muscle Strength and Lanza et al (12 - 18 Years Old) and Mendes et al (12 - 18 Years Old) Predicted Equations

Respiratory muscle strength

Mean difference between measured and predicted values (95% CI)

ICC (95% CI)

MIP: maximal inspiratory pressure; MEP: maximal expiratory pressure; CI: confidence interval; ICC: intraclass correlation coefficient.

MIP, cm H₂O

Measured (n = 100)

96 ± 28

Predicted by Lanza et al [9]

105 ± 5

-10 (-16 to -3)

0.002

0.2 (-0.1 - 0.5)

0.108

Predicted by Mendes et al [13]

92 ± 15

4 (-3 - 10)

0.466

0.5 (0.2 - 0.6)

0.001

MEP, cm H₂O

Measured (n = 100)

98 ± 24

Predicted by Lanza et al [9]

104 ± 9

-6 (-11 - 1)

0.013

0.4 (0.2 - 0.6)

0.001

Predicted by Mendes et al [13]

106 ± 17

-8 (-14 to -3)

0.001

0.6 (0.4 - 0.7)

< 0.001

**Table 4.** Comparison Between Measured Respiratory Muscle Strength and Domenech-Clar et al (8 - 17 Years Old), Lanza et al (8 - 18 Years Old), and Wilson et al (7 - 17 Years Old) Predicted Equations
	Respiratory muscle strength	Mean difference between measured and predicted values (95% CI)	P	ICC (95% CI)	P
MIP: maximal inspiratory pressure; MEP: maximal expiratory pressure; CI: confidence interval; ICC: intraclass correlation coefficient.
MIP, cm H₂O, n = 137
Measured	92 ± 27	-	-	-	-
Predicted by Domenech-Clar et al [10]	98 ± 20	-6 (-12 - 0)	0.055	0.6 (0.4 - 0.7)	< 0.00
Predicted by Lanza et al [9]	99 ± 10	-8 (-13 to -2)	0.003	0.5 (0.3 - 0.6)	< 0.001
Predicted by Wilson et al [14]	77 ± 14	15 (9 - 21)	< 0.001	0.5 (0.2 - 0.6)	< 0.001
MEP, cm H₂O, n = 138
Measured	94 ± 23	-	-	-	-
Predicted by Domenech-Clar et al [10]	126 ± 34	-32 (-39 to -25)	< 0.001	0.5 (-0.1 - 0.7)	< 0.001
Predicted by Lanza et al [9]	102 ± 9	-8 (-12 to -3)	< 0.001	0.5 (0.3 - 0.7)	< 0.001
Predicted by Wilson et al [14]	96 ± 19	-2 (-6 - 3)	1.0	0.7 (0.6 - 0.8)	< 0.001

Table 4. Comparison Between Measured Respiratory Muscle Strength and Domenech-Clar et al (8 - 17 Years Old), Lanza et al (8 - 18 Years Old), and Wilson et al (7 - 17 Years Old) Predicted Equations

Respiratory muscle strength

Mean difference between measured and predicted values (95% CI)

ICC (95% CI)

MIP: maximal inspiratory pressure; MEP: maximal expiratory pressure; CI: confidence interval; ICC: intraclass correlation coefficient.

MIP, cm H₂O, n = 137

Measured

92 ± 27

Predicted by Domenech-Clar et al [10]

98 ± 20

-6 (-12 - 0)

0.055

0.6 (0.4 - 0.7)

< 0.00

Predicted by Lanza et al [9]

99 ± 10

-8 (-13 to -2)

0.003

0.5 (0.3 - 0.6)

< 0.001

Predicted by Wilson et al [14]

77 ± 14

15 (9 - 21)

< 0.001

0.5 (0.2 - 0.6)

< 0.001

MEP, cm H₂O, n = 138

Measured

94 ± 23

Predicted by Domenech-Clar et al [10]

126 ± 34

-32 (-39 to -25)

< 0.001

0.5 (-0.1 - 0.7)

< 0.001

Predicted by Lanza et al [9]

102 ± 9

-8 (-12 to -3)

< 0.001

0.5 (0.3 - 0.7)

< 0.001

Predicted by Wilson et al [14]

96 ± 19

-2 (-6 - 3)

1.0

0.7 (0.6 - 0.8)

< 0.001