J Clin Med Res

Journal of Clinical Medicine Research, ISSN 1918-3003 print, 1918-3011 online, Open Access

Article copyright, the authors; Journal compilation copyright, J Clin Med Res and Elmer Press Inc

Journal website http://www.jocmr.org

Original Article

Volume 9, Number 4, April 2017, pages 289-296

How Mechanical Ventilation Measurement, Cutoff and Duration Affect Rapid Shallow Breathing Index Accuracy: A Randomized Trial

**Table 1.** Demographic Data for the 40 Patients Included in the Study, Grouped According to Duration of the Mechanical Ventilation
Characteristics	General (n = 40)	Group submitted to MV < 72 h (n = 17)	Group submitted to MV > 72 h (n = 23)	P value
MV: mechanical ventilation; APACHE II: Acute physiology age chronic health evaluation; NS: without statistical significance. Values expressed as the mean and standard deviation.
Age (years)	58 ± 15	52 ± 14	58 ± 15	NS
Gender
Male	24 (60%)	10	14
Female	16 (40%)	7	9
APACHE II score	24 ± 7	24 ± 9	23 ± 6	NS
Period of intubation (days)	6 ± 4	2 ± 1	8 ± 3	< 0.003
Causes of respiratory insufficiency
Cardiovascular	1	1	0
Hematological	3	2	1
Renal metabolism	6	2	4
Neurological	5	3	2
Respiratory	8	3	5
Trauma/surgical	5	2	3
Oncological	3	0	3
Vascular	2	1	1
Others	7	3	4

Table 1. Demographic Data for the 40 Patients Included in the Study, Grouped According to Duration of the Mechanical Ventilation

Characteristics

General (n = 40)

Group submitted to MV < 72 h (n = 17)

Group submitted to MV > 72 h (n = 23)

P value

MV: mechanical ventilation; APACHE II: Acute physiology age chronic health evaluation; NS: without statistical significance. Values expressed as the mean and standard deviation.

Age (years)

58 ± 15

52 ± 14

58 ± 15

Gender

Male

24 (60%)

Female

16 (40%)

APACHE II score

24 ± 7

24 ± 9

23 ± 6

Period of intubation (days)

6 ± 4

2 ± 1

8 ± 3

< 0.003

Causes of respiratory insufficiency

Cardiovascular

Hematological

Renal metabolism

Neurological

Respiratory

Trauma/surgical

Oncological

Vascular

Others

**Table 2.** Values of RSBI as Obtained From Tested Methods, According to Mechanical Ventilation Duration
Up to 72 h of MV (n = 18)	Over 72 h of MV (n = 23)
RSBI: rapid shallow breathing index; MIN: obtained with pressure support of 5 cm H₂O and PEEP of 5 cm H₂O; ATC: obtained in the automatic tube compensation mode and PEEP of 5 cm H₂O); SP: obtained with the patient disconnected from mechanical ventilation; NS: without statistical significance. *Intragroup comparison ( RSBI_SP). #Intergroup comparison ( RSBI_SP over 72 h).
38 ± 18#	46 ± 24#	55 ± 22#	39 ± 14*	51 ± 19*	78 ± 29
CI: -59.69 to -20.06 #P = 0.000	CI: 12.41 - 52.05 #P = 0.000	CI: -43.22 to -3.58 #P = 0.039	CI : -57.62 to -21.07 *P = 0.000	CI: 8.46 - 45.01 *P = 0.000

Table 2. Values of RSBI as Obtained From Tested Methods, According to Mechanical Ventilation Duration

Up to 72 h of MV (n = 18)

Over 72 h of MV (n = 23)

RSBI_MIN

RSBI_ATC

RSBI_SP

RSBI_MIN

RSBI_ATC

RSBI_SP

RSBI: rapid shallow breathing index; MIN: obtained with pressure support of 5 cm H₂O and PEEP of 5 cm H₂O; ATC: obtained in the automatic tube compensation mode and PEEP of 5 cm H₂O); SP: obtained with the patient disconnected from mechanical ventilation; NS: without statistical significance. *Intragroup comparison ( RSBI_SP). #Intergroup comparison ( RSBI_SP over 72 h).

38 ± 18#

46 ± 24#

55 ± 22#

39 ± 14*

51 ± 19*

78 ± 29

CI: -59.69 to -20.06
#P = 0.000

CI: 12.41 - 52.05
#P = 0.000

CI: -43.22 to -3.58
#P = 0.039

CI : -57.62 to -21.07
*P = 0.000

CI: 8.46 - 45.01
*P = 0.000

**Table 3.** RSBI Values Obtained From Tested Methods, According to Results of Mechanical Ventilation Duration and Extubation
Group	Up to 72 h of MV	Over 72 h of MV
RSBI: rapid shallow breathing index; MIN: obtained with pressure support of 5 cm H₂O and PEEP of 5 cm H₂O; ATC: obtained in the automatic tube compensation mode and PEEP of 5 cm H₂O; SP: obtained with the patient disconnected from mechanical ventilation; NS: without statistical significance. *Intragroup comparison ( RSBI_SP). #Intergroup comparison ( RSBI_SP failed).
Success	38 ± 20# CI: -89.61 to -6.5 #P = 0.01	45 ± 26	51 ± 22	37 ± 16# CI: -54.77 to -1.22 P = 0.03 CI: -85.25 to -30.49 #P = 0.00	45 ± 19# CI: 21.99 - 76.75 #P = 0.000	58 ± 18# #P = 0.02 CI: -29.87 to -57.25
Failed	39 ± 7	52 ± 5	73 ± 9	41 ± 10 CI: -81.33 to -25.39 P = 0.000	58 ± 18 CI: 8.30 - 64.24 P = 0.001	93 (28)

Table 3. RSBI Values Obtained From Tested Methods, According to Results of Mechanical Ventilation Duration and Extubation

Group

Up to 72 h of MV

Over 72 h of MV

RSBI_MIN

RSBI_ATC

RSBI_SP

RSBI_MIN

RSBI_ATC

RSBI_SP

RSBI: rapid shallow breathing index; MIN: obtained with pressure support of 5 cm H₂O and PEEP of 5 cm H₂O; ATC: obtained in the automatic tube compensation mode and PEEP of 5 cm H₂O; SP: obtained with the patient disconnected from mechanical ventilation; NS: without statistical significance. *Intragroup comparison ( RSBI_SP). #Intergroup comparison ( RSBI_SP failed).

Success

38 ± 20#
CI: -89.61 to -6.5
#P = 0.01

45 ± 26

51 ± 22

37 ± 16*#
CI: -54.77 to -1.22
*P = 0.03
CI: -85.25 to -30.49
#P = 0.00

45 ± 19#
CI: 21.99 - 76.75
#P = 0.000

58 ± 18#
#P = 0.02
CI: -29.87 to -57.25

Failed

39 ± 7

52 ± 5

73 ± 9

41 ± 10
*CI: -81.33 to -25.39
*P = 0.000

58 ± 18
*CI: 8.30 - 64.24
*P = 0.001

93 (28)

**Table 4.** Accuracy of the RSBI to Predict Successful Extubation With Cutoff Points of 50, 78, and 105 Cycles/Min/L Using Different Methods
Cutoff	Method	Sensitivity	Specificity	Positive predictive value	Negative predictive value	Accuracy
RSBI: rapid shallow breathing index; MIN: obtained with pressure support of 5 cm H₂O and PEEP of 5 cm H₂O; ATC: obtained in the automatic tube compensation mode and PEEP of 5 cm H₂O; SP: obtained with the patient disconnected from mechanical ventilation.
50	RSBI_MIN	0.92	0.27	0.58	0.75	0.61
	RSBI_ATC	0.75	0.55	0.64	0.67	0.65
	RSBI_SP	0.33	0.91	0.80	0.56	0.61
78	RSBI_MIN	0.92	0.00	0.50	0.00	0.48
	RSBI_ATC	0.92	0.27	0.58	0.75	0.61
	RSBI_SP	0.75	0.73	0.75	0.73	0.74
105	RSBI_MIN	1.0	0.00	0.50	1.00	0.50
	RSBI_ATC	1.0	0.00	0.52	1.00	0.52
	RSBI_SP	0.92	0.27	0.58	0.75	0.61

Table 4. Accuracy of the RSBI to Predict Successful Extubation With Cutoff Points of 50, 78, and 105 Cycles/Min/L Using Different Methods

Cutoff

Method

Sensitivity

Specificity

Positive predictive value

Negative predictive value

Accuracy

RSBI_MIN

0.92

0.27

0.58

0.75

0.61

RSBI_ATC

0.75

0.55

0.64

0.67

0.65

RSBI_SP

0.33

0.91

0.80

0.56

0.61

RSBI_MIN

0.92

0.00

0.50

0.00

0.48

RSBI_ATC

0.92

0.27

0.58

0.75

0.61

RSBI_SP

0.75

0.73

0.75

0.73

0.74

105

RSBI_MIN

1.0

0.00

0.50

1.00

0.50

RSBI_ATC

1.0

0.00

0.52

1.00

0.52

RSBI_SP

0.92

0.27

0.58

0.75

0.61