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18218

Respiratory Severity Score As a Predictor of Bronchopulmonary Dysplasia and Mortality

Friday, October 19, 2012
Room R02-R05 (Morial Convention Center)
Zeenia Billimoria, M.D., Nileshkumar Patel, MD and Sanjay Chawla, MD, Childrens Hospital of Michigan, Detroit, MI

Purpose

Respiratory severity score (RSS) is an objective marker of severity of respiratory illness. It is a product of mean airway pressure (MAP) and fraction of inspired oxygen (FiO2). RSS and its effect on bronchopulmonary dysplasia (BPD) and mortality are unknown.

To determine if RSS can predict composite outcome of BPD and mortality.

Methods

We used the NHLBI limited access data set of High Frequency Ventilation in Premature Infants (HIFI). All participants with birth weight ≤ 1500gms and gestational age ≤ 30 weeks were included (n=477). RSS was calculated on the first day of life using the first available of 3 pre-randomization blood gases. RSS was split into tertiles. Multivariate logistic regression analysis was carried out. The end points were BPD (defined as (1) the need for supplemental oxygen on the 28th day of post-natal life and for more than 21 of the 28 days after birth and (2) abnormal chest radiographic findings that persisted until the 28th day of life), air leaks and mortality.

Results

BPD (HR 8.13 95% CI 3.76-17.6, p value <0.01), air leaks (HR 8.37 95% CI 4.62-15.16, p value <0.01) and mortality (HR 5.11 95% CI 2.6-10.03, p value <0.01) increased with a rising RSS. Males were more likely to have a worse outcome. Overall, there was a low rate of antenatal steroid use. (Table 1)

Conclusion

These findings need to be confirmed in future studies involving larger number of participants with increased use of antenatal steroids. Although HIFI trial is outdated, we present a large analysis demonstrating high rate of BPD and mortality with rising RSS.

Table 1. Baseline Characteristics of the study population

Respiratory Score

Variables (Mean SD or n (%)

0.92-5.20

5.28-9.00

9.03-23

P for trend

Randomization to High Frequency Oscillator Ventilation

45.4%

45.3%

48.3%

0.84

Birth weight

983.2 147.5

998.1 165.6

1043.3 218.3

<0.01

Gestational age

27.1 1.6

27.3 1.6

27.2 1.8

0.76

Male

68 (44.7)

96 (64.9)

94 (63.9)

<0.01

Maternal age

27.2 6.3

25.5 5.6

26.1 5.3

0.08

Apgar score 5 min

6.9 1.7

6.6 1.8

5.9 2.2

<0.01

PIH

17 (11.3)

35 (23.9)

11 (7.6)

<0.01

Gestational diabetes

4 (2.7)

4 (2.7)

1 (0.7)

0.38

Antenatal steroid

45 (29.6)

33 (22.3)

15 (10.2)

<0.01

Chorioamnionitis

21 (14.1)

16 (10.9)

26 (18.1)

0.22

Prolonged rupture of membrane

5 (3.6)

6 (4.8)

4 (3.1)

0.78

Mortality

20 (13.2)

32 (21.6)

66 (44.9)

<0.01

BPD*

53 (40.2)

67 (57.8)

54 (66.7)

<0.01

BPD/Mortality

73 (48)

98 (66.9)

120 (81.6)

<0.01

Air leaks

30 (19.7)

73 (49.3)

94 (63.9)

<0.01

*BPD data available only in 132, 116 and 81 patients in the 3 tertiles respectively.