1. CORRELATION BETWEEN OXYGEN USE AND SYSTEMIC HYPERTENSION
IN PRETERM NEONATE
Astha Koolwal MBBS, Rakesh Sharma MD, Gary Stahl MD, Alla Kushnir MD Department of Pediatrics, Cooper University Hospital, Camden, NJ
ABSTRACT
Introduction: Systemic hypertension is seen in 2% of all neonates with consequences such as heart failure, early onset of atherosclerosis, and renal disease. The association between BPD and systemic hypertension has long been studied. The mechanism behind the association between hypertension and BPD is not clear. It is well accepted that the presence of oxygen free radicals (reactive oxygen species) is a reason for the development of histo-pathological changes in BPD. There are isolated studies depicting the correlation between systemic hypertension and reactive oxygen species in adults. Extra-corporeal Membrane Oxygenation (ECMO) has been seen to increase the level of reactive oxygen species. This therefore raises the question of oxygen therapy being a common etiology for both BPD and neonatal hypertension.
Objective/Purpose: To determine whether supplemental oxygen affects the development of systemic hypertension in preterm neonates after the first month of life.
Methods: IRB approved retrospective data analysis of all infants born in Cooper NICU ≥32 weeks gestation who received oxygen supplementation was identified. Patient’s systolic blood pressure (SBP) and mean arterial pressure (MAP) were recorded and averaged on day of life 14, 21, and weekly until discharge. Systolic blood pressure and mean arterial pressure ≥ 95% for gestational age and gender were considered as systemic hypertension. Demographic information as well as common comorbidities were recorded. Duration and type of oxygen therapy, respiratory drug therapy, presence of BPD and the use of umbilical arterial catheter (UAC) were evaluated in relation to systemic hypertension.
Results: Total of 180 preterm infants from 11/2010 to 7/2014 were included, with 43 (24%) that had systemic hypertension (HTN) and 37 (21%) who had HTN in the second month. Presence of HTN was not related to increased incidence of BPD, number of days ventilated or on oxygen. Risk of HTN in the second month of life was 3 times higher in those with BPD (p=0.001, OR %CI 1.5, 7.2) and significantly higher with longer exposure to oxygen (p=0.01). While presence versus absence of UAC had no effect on development of HTN,duration the UAC was present increased the chance of HTN (p=0.05). In neonates ≥28 weeks gestation BPD increased the risk of HTN almost 5 times (p=0.004, OR %CI 1.6,13.1).
Conclusion: BPD and duration of oxygen exposure significantly increase the risk of HTN in neonates, which was more pronounced in those ≥ 28 weeks gestation.
METHODS
IRB approved retrospective data analysis
Infants born in Cooper NICU ≥32 weeks gestation and received oxygen supplementation
Patient’s systolic blood pressure (SBP) and mean arterial pressure (MAP) were recorded on day of life 14, 21, and weekly until discharge.
Systolic blood pressure and mean arterial pressure ≥ 95% for gestational age and gender were considered as systemic hypertension.
Demographic information as well as common comorbidities were recorded.
Duration and type of oxygen therapy, respiratory drug therapy, presence of BPD and the use of umbilical arterial catheter (UAC) were evaluated.
Effect of UAC Duration on
Development of Hypertension after 1 Month
Characteristics for
Hypertension after 1st Month
No HTN
N= 143
HTN
N=37 p
Gender, %
Males 55 48
0.58
Race, %
0.65
Caucasian 43 34
African-American 38
Hispanic 19 23
Birth weight, grams
1087
962
0.02*
Gestational Age, weeks
28.3
27.1
0.002*
Mode of Delivery
Vaginal, % 50
0.47 *
BACKGROUND
Systemic hypertension is seen in 2% of all neonates with consequences such as heart failure, early onset of atherosclerosis, and renal disease. The association between BPD and systemic hypertension has long been studied. The mechanism behind the association between hypertension and BPD is not clear. It is well accepted that the presence of oxygen free radicals (reactive oxygen species) is a reason for the development of histo-pathological changes in BPD. There are isolated studies depicting the correlation between systemic hypertension and reactive oxygen species in adults. Extra-corporeal Membrane Oxygenation (ECMO) has been seen to increase the level of reactive oxygen species. This therefore raises the question of oxygen therapy being a common etiology for both BPD and neonatal hypertension.
RESULTS
Of total 180 preterm infants from 11/2010 to 7/2014 that were included, 43 (24%) had systemic hypertension (HTN) and 37 (21%) had HTN in the second month.
Presence of any HTN was not related to the incidence of BPD, number of days ventilated or on oxygen.
Risk of HTN in the 2nd month of life was 3 times higher in those with BPD (p=0.001, OR %CI 1.5, 7.2).
Risk of HTN in the 2nd month was significantly higher with longer exposure to oxygen (p=0.01).
While presence vs absence of UAC had no effect on development of HTN, duration of UAC increased the chance of HTN (p=0.02).
There was a 5 times increase risk of HTN in neonates ≥28 weeks gestation with BPD (p=0.004, OR % CI 1.6,13.1).
Respiratory and Clinical Outcomes for
Hypertension after 1st Month
Effect of Oxygen on
Development of Hypertension after 1 Month
No HTN
N = 143
HTN
N=37 p
BPD, n (%)
55 (38)
25 (68)
0.001 *
IVH, n (%)
44 (31)
10 (27)
0.42
ROP, n (%)
48 (34)
22 (59)
0.03*
Severe ROP, n (%)
26 (18)
0.39
Mean Days Ventilated 26 33
0.31
Mean Days on Oxygen 47 69
0.002*
Rate of postnatal steroids, n (%)
18 (13)
8 (22)
0.16
Use of Caffeine, n (%)
133 (93)
35 (95)
0.73
Presence of UAC, n (%)
81 (57)
26 (70)
0.13
Mean Duration of UAC, days
3.6
5.7
0.02*
Mean Length of Stay, days
73.4
88.4
0.01* *
CONCLUSIONS
BPD and duration of oxygen exposure increased the risk of HTN in preterm infants. This was more pronounced in neonates ≥ 28 weeks gestation.
OBJECTIVE
To determine whether supplemental oxygen affects the development of systemic hypertension in preterm neonates after the first month of life.
REFERENCES
1. Abman SH, Warady BA, Lum GM, Koops BL (1984) Systemic hypertension in infants with bronchopulmonary dysplasia. J Pediatr 104:928–31.
2. Saugstad OD (2003) Bronchopulmonary dysplasia-oxidative stress and antioxidants. Semin Neonatol 8:39–49.
3. Madurga A, Mizíková I, Ruiz-Camp J, Morty RE (2013) Recent advances in late lung development and the pathogenesis of bronchopulmonary dysplasia. Am J Physiol Lung Cell Mol Physiol 305:L893–905. doi: /ajplung
4. Hayes RA, Shekar K, Fraser JF (2013) Is hyperoxaemia helping or hurting patients during extracorporeal membrane oxygenation? Review of a complex problem. Perfusion 28:184–93. doi: /
* p<0.05