Dexamethasone and hypertension in preterm infants

Neonatal hypertension: concerns within and beyond the neonatal intensive care unit

Neonatal hypertension occurs in 1%-2% of neonates in the neonatal intensive care unit (NICU) although may be underdiagnosed. Blood pressure values in premature neonates change rapidly in the first days and weeks of life which may make it more difficult to recognize abnormal blood pressure values. In addition, the proper blood pressure measurement technique must be used to ensure the accuracy of the measured values as most blood pressure devices are not manufactured specifically for this population. In premature neonates, the cause of the hypertension is most commonly related to prematurity-associated complications or management while in term neonates is more likely to be due to an underlying condition. Both oral and intravenous antihypertensive medications can be used in neonates to treat high blood pressure although none are approved for use in this population by regulatory agencies. The natural history of most neonatal hypertension is that it resolves over the first year or two of life. Of concern are the various neonatal risk factors for later cardiovascular and kidney disease that are present in most NICU graduates. Prematurity increases the risk of adulthood hypertension while intrauterine growth restriction may even lead to hypertension during childhood. From neonates through to adulthood NICU graduates, this review will cover each of these topics in more detail and highlight the aspects of blood pressure management that are established while also highlighting where knowledge gaps exist.

Postnatal glucocorticoid use impacts renal function in VLBW neonates

BACKGROUND

Preterm neonates often require glucocorticoids to manage refractory hypotension, prevent, and treat bronchopulmonary dysplasia. We have investigated the effect of cumulative dose and duration of glucocorticoids on blood pressure and renal function in VLBW infants.

METHODS

In this retrospective cohort study, medical records of infants (GA ≤ 35 weeks) born January 2015 to December 2019 were reviewed to extract demographic and clinical characteristics, dose and duration of steroids, blood pressure (BP), and creatinine at the time of discharge from the neonatal intensive care unit.

RESULTS

Two hundred and eighty-three neonates with average GA (28 ± 3 weeks) and birthweight (1060±381 g). Twenty-eight percent (33/116) of infants who received postnatal steroids developed hypertension versus 16% (27/167) of controls (OR = 2.0, p = 0.011). There was a correlation between the cumulative dosage of postnatal steroids and systolic BP (R² = 0.06, p < 0.001). With increasing steroid dose and total steroid days, there was a significant increase in creatinine clearance at the time of discharge (R² = 0.13, p < 0.001; R² = 0.13, p < 0.001, respectively).

CONCLUSIONS

Cumulative dose of postnatal steroids and duration of use is associated with increased systolic BP in premature infants. Postnatal steroids should be used prudently to prevent long-term cardiovascular and renal morbidity.

IMPACT

Preterm neonates are exposed to a high dose of glucocorticoids during their neonatal intensive care stay. The dose and duration of use of postnatal glucocorticoids was associated with significant increase in blood pressure at the time of discharge in preterm neonates. Postnatal glucocorticoid use is associated with improved creatinine clearance likely due to a state of hyperfiltration and may lead to chronic kidney disease later in life. Postnatal glucocorticoids should be used prudently in this highly vulnerable population.

Elimination of Intravenous Di-2-Ethylhexyl Phthalate Exposure Abrogates Most Neonatal Hypertension in Premature Infants with Bronchopulmonary Dysplasia

(1) Background: The incidence of hypertension in very low birthweight (VLBW) infants in a single neonatal intensive care unit (NICU) dropped markedly during a 2-year period when the IV fluid (IVF) in both the antenatal unit and the NICU temporarily changed to a di-2-ethylhexyl phthalate (DEHP)-free formulation. The objective of the current report is to document this observation and demonstrate the changes in incidence of hypertension were not associated with the variation in risk factors for hypertension; (2) Methods: The charts of all VLBW infants born in a single NICU during a 7-year span were reviewed. This time includes 32 months of baseline, 20 months of DEHP-free IVF, 20 months of IVF DEHP re-exposure, and two 4-month washout intervals. The group of interest was limited to VLBW infants with bronchopulmonary dysplasia (BPD). Chi-square analysis was used to compare incidence of hypertension among periods. Vermont Oxford NICU Registry data were examined for variation in maternal and neonatal risk factors for hypertension; Results: Incidence of hypertension in VLBW infants with BPD decreased from 7.7% (baseline) to 1.4% when IVF was DEHP-free, rising back to 10.1% when DEHP-containing IVF returned to use. Risk factors for neonatal hypertension were stable across the 3 study periods in the NICU’s group of VLBW infants; (3) Conclusions: Serendipitous removal of IVF containing DEHP resulted in near elimination of hypertension in one NICU—an effect entirely reversed after the same brand of DEHP-containing IVF returned to clinical use. These results suggest that DEHP exposure from IVF plays a major role in neonatal hypertension.

The changing spectrum of hypertension in premature infants

OBJECTIVE

The objective is to document changes in the etiologic spectrum of hypertension in premature infants.

STUDY DESIGN

We reviewed all cases of systemic hypertension (HTN) in premature infants at two centers over 8 years. Infants were sorted into categorical groups as described in 2012 by Flynn. Analyses included frequency of diagnosis, timecourse of HTN, and diagnostics. Phthalate exposure via intravenous fluid and respiratory equipment was compared among groups and centers.

RESULTS

One hundred and twenty-nine infants having 130 episodes of HTN met the inclusion criteria. Sixty-five percent of cases were classified as pulmonary and 16% as miscellaneous. Plasma renin activity (PRA) was undetectable or <11 ng/mL/h in almost all hypertensive infants. Cases categorized as Pulmonary, medications/intoxications, and miscellaneous presented near 40 weeks postmenstrual age, with low PRA and large phthalate exposures.

CONCLUSIONS

High PRA HTN has been replaced by low PRA in most cases, and may be due to phthalate exposure.

Characteristics of hypertension in premature infants with and without chronic lung disease: a long-term multi-center study

BACKGROUND

Many causes for neonatal hypertension in premature infants have been described; however in some cases no etiology can be attributed. Our objectives are to describe such cases of unexplained hypertension and to compare hypertensive infants with and without chronic lung disease (CLD).

METHODS

We reviewed all cases of hypertension in premature infants referred from 18 hospitals over 16 years. Inclusion criteria were hypertension occurring at <6 months of age and birth at <37 weeks gestation; the main exclusion criterion was known secondary hypertension. Continuous variables were compared using analysis of variance. Nominal variables were compared using chi-square tests.

RESULTS

A total of 97 infants met the inclusion criteria, of whom 37 had CLD. Among these infants, hypertension presented at a mean of 11.3 ± 3.2 chronological weeks of age and a postmenstrual age of 39.6 ± 3.6 weeks. Diagnostic testing was notable for plasma renin activity (PRA) being <11 ng/mL/h in 98% of hypertensive infants. Spironolactone was effective monotherapy in 51 of 56 cases of hypertension. Hypertension resolved in all infants, with an average treatment duration of 25 weeks. Significant differences between the two groups of infants were a 0.4 kg lower birthweight and a 2.5 weeks younger gestational age at birth in those with CLD (p < 0.01, p < 0.01, respectively). Hypertension presented in those with CLD 1.8 weeks later, but at the same postmenstrual age as those without CLD (p < 0.01, p = 0.45, respectively).

CONCLUSION

Premature infants with unexplained hypertension, with and without CLD, presented at a postmenstrual age of 40 weeks with low PRA, transient time course, and a favorable response to spironolactone treatment.

Neonatal hypertension

Neonatal hypertension (HT) is a frequently under reported condition and is seen uncommonly in the intensive care unit. Neonatal HT has defined arbitrarily as blood pressure more than 2 standard deviations above the base as per the age or defined as systolic BP more than 95% for infants of similar size, gestational age and postnatal age. It has been diagnosed long back but still is the least studied field in neonatology. There is still lack of universally accepted normotensive data for neonates as per gestational age, weight and post-natal age. Neonatal HT is an important morbidity that needs timely detection and appropriate management, as it can lead to devastating short-term effect on various organs and also poor long-term adverse outcomes. There is no consensus yet about the treatment guidelines and majority of treatment protocols are based on the expert opinion. Neonate with HT should be evaluated in detail starting from antenatal, perinatal, post-natal history, and drug intake by neonate and mother. This review article covers multiple aspects of neonatal hypertension like definition, normotensive data, various etiologies and methods of BP measurement, clinical features, diagnosis and management.

Hypertension in infancy: diagnosis, management and outcome

Advances in the ability to identify, evaluate, and care for infants with hypertension, coupled with advances in the practice of Neonatology, have led to an increased awareness of hypertension in modern neonatal intensive care units. This review will present updated data on blood pressure values in neonates, with a focus on the changes that occur over the first days and weeks of life in both term and preterm infants. Optimal blood pressure measurement techniques as well as the differential diagnosis of hypertension in the neonate and older infants will be discussed. Recommendations for the optimal immediate and long-term evaluation and treatment, including potential treatment parameters, will be presented. We will also review additional information on outcome that has become available over the past decade.

Conditions associated with hypertension in a high-risk premature infant

Hypertension is an uncommon but significant problem in high-risk neonates and infants, and the spectrum of potential causes is broad. Here, we describe an extremely premature infant (birth weight, 728 g; gestational age, 27 weeks) with multiple complications and hypertension. During admission, umbilical artery catheters were used for a period of time, and he suffered from respiratory distress syndrome, intraventricular hemorrhage, pulmonary hemorrhage, patent ductus arteriosus, pericardial effusion, heart failure, repeated sepsis, anemia, thrombocytopenia, chronic lung disease, and progressive liver damage. He was treated with multiple medications, including erythropoietin, indomethacin, epinephrine, dopamine, aminophylline, multiple antibiotics, amphotericin B, and total parenteral nutrition. Hypertension was first noted when he was 41 days old, with spontaneous remission. It then recurred, reaching higher than 100 mmHg when he was almost 4 months old. After stopping erythropoietin, hypertension subsided for a short period of time and went up again. Multiple factor-related hypertension in this premature infant was considered. Related literature on hypertension in premature infants is reviewed. In conclusion, multiple factors can influence blood pressure and may induce hypertension in high-risk premature infants. Thus, blood pressure should be closely monitored in high-risk premature infants. Judicious use of all medications and interventions are crucial to decrease the incidence of hypertension in high-risk premature infants.

Systolic blood pressure in babies of less than 32 weeks gestation in the first year of life. Northern Neonatal Nursing Initiative

AIM

To define the normal range of systolic blood pressure in a non-selective population based sample of babies of low gestation throughout early infancy.

METHODS

Daily measurements of systolic blood pressure were made in all the babies of less than 32 weeks gestation born in the North of England in 1990 and 1991 during the first 10 days of life. Additional measurements were obtained from 135 of these babies throughout the first year of life. Systolic pressure was measured by sensing arterial flow with a Doppler ultrasound probe. It was assumed that blood pressure had never been pathologically abnormal in the neonatal period if the child was alive and free from severe disability two years later. Data of adequate quality were available from 398 such children. Additional data wer collected, for comparative purposes, from 123 babies of 32, 36, or 40 weeks of gestation.

RESULTS

Systolic pressure correlated with weight and gestation at birth, and rose progressively during the first 10 days of life. The coefficient of variation did not vary with gestational or postnatal age (mean value 17%), the relation with gestation being closer than with birthweight. Systolic pressure rose 20% during the first 10 days from an initial mean of 42 mm Hg in babies of 24 weeks gestation, and by 42% from an initial mean of 48 mm Hg in babies of 31 weeks gestation. These findings were not altered by the exclusion of data from 14 babies who had inotropic support during this time. Simultaneous measurements in three centres using an oscillometric technique revealed that this technique tended to overestimate systolic pressure when this was below average. Systolic pressure finally stabilised at a mean of 92 (95% CI 72-112) mm Hg at a postconceptional age of 44-48 weeks irrespective of gestation at birth.

CONCLUSION

Systolic blood pressure 4-24 hours after birth was less than gestational age (in weeks) in only 3% of non-disabled long term survivors. Systolic pressure rose with increasing gestation and increasing postnatal age, but stabilised some six weeks after term, regardless of gestation at birth.

Effects of dexamethasone on blood pressure in premature infants with bronchopulmonary dysplasia

OBJECTIVE

To determine the incidence and time course of blood pressure elevation in dexamethasone-treated premature infants with bronchopulmonary dysplasia.

METHODS

In a prospective, self-controlled, consecutive case study, 16 ventilator-dependent very low birth weight neonates treated with dexamethasone were studied. Systolic, diastolic, and mean arterial pressure and heart rate were recorded at three specific times daily. Data were recorded from day 1 of dexamethasone treatment through the duration of therapy and up to 2 weeks after its completion. Retrospective daily data were collected for up to 14 days before therapy.

RESULTS

The 788 daily observations (a systolic and diastolic average of the three blood pressure recordings per day) were recorded for 16 infants, a mean of 49 +/- 11 daily observations each (range, 24 to 67). Systolic and diastolic blood pressures before dexamethasone therapy were correlated to corrected gestational age. At initiation of dexamethasone, blood pressures increased significantly from days 1 to 2. For all observations, mean systolic pressure was 51 +/- 9.5 mm Hg before dexamethasone therapy, compared with 64 +/- 10.2 mm Hg during therapy (p < 0.01); diastolic pressure was 29 +/- 6.7 mm Hg before therapy compared with 41 +/- 8.2 mm Hg during therapy (p < 0.01). After completion of dexamethasone therapy, pressures continued to increase: systolic, 67 +/- 8.8 mm Hg (p < 0.01); diastolic, 42 +/- 6.2 mm Hg (not significant). Both systolic and diastolic pressures increased as a function of weight and age; when we controlled for these covariates, an independent effect of dexamethasone itself on the group was shown. Of the 2182 individual systolic pressure readings, 9.4% were considered in the hypertensive range. The six infants treated with hydralazine had higher mean systolic pressures before dexamethasone therapy than did infants without hydralazine (56 +/- 9.4 mm Hg vs 46 +/- 6.4 mm Hg; p < 0.001) and were 2 weeks older at initiation of therapy.

CONCLUSIONS

Blood pressure significantly increases during dexamethasone therapy, particularly within the first 48 hours, and does not return to baseline levels after therapy. Those infants most likely to be labeled hypertensive tend to be older at initiation of therapy but do not appear to have any other significant risk factors.

Dexamethasone associated systemic hypertension in low birth weight babies with chronic lung disease

To assess the role of dexamethasone treatment as a cause of systemic hypertension and associated complications, blood pressure was registered prospectively before, during and after a 4-week dexamethasone course in 22 neonates with chronic lung disease. In all patients systolic blood pressure rose significantly during treatment (median rise 34 mm Hg, range 4-->59 mm Hg), without complications attributable to hypertension. In all but one patient blood pressure returned to pretreatment values within 2 weeks after stopping dexamethasone treatment.

CONCLUSION

Dexamethasone induced hypertension is transient, even after a 4-week course, and is not associated with hypertensive complications, so treatment is not necessary. When hypertension persists after dexamethasone withdrawal other causes should be considered.

Effect of dexamethasone on protein metabolism in infants with bronchopulmonary dysplasia

Corticosteroids result in protein wasting in human adults and rats. To determine to what extent this therapy affects protein metabolism in preterm infants, we studied 10 very low birth weight infants before a gradually tapered dexamethasone regimen was started and at day 4 of treatment (dexamethasone dosage 0.35 +/- 0.09 mg.kg-1.day-1), and seven infants at day 19 of treatment (dexamethasone dosage, 0.10 +/- 0.01 mg.kg-1.day-1). Protein breakdown and turnover rates were increased at day 4 of treatment but not any more at day 19 of treatment. Protein synthesis rate was not significantly affected during dexamethasone therapy. Weight gain was severely diminished during the first week of treatment but not during the next 2 weeks. We conclude that nitrogen balance during high dosages of dexamethasone is significantly lower because of an increase in proteolysis and not because of a suppression of synthesis.

Prediction of chronic lung disease from the chest radiograph appearance at seven days of age

The aim of this study was to assess if the chest radiograph appearance at seven days of age could be used to predict chronic lung disease (oxygen dependency at 28 days of age). Sixty preterm infants (median gestational age 28 weeks), who were ventilated and/or had supplementary oxygen at seven days of age and had a chest radiograph performed at that postnatal age, were prospectively recruited. These chest radiographs were scored according to lung volume, presence of opacification, haziness, interstitial changes and cystic elements (maximum score 18). Twenty-eight infants subsequently developed chronic lung disease; their median chest radiograph score was 5.5 (range 2-14) which was significantly higher than that of the non-chronic lung disease infants (median 3; range 0-6). A chest radiograph score of 4 had a 71% sensitivity and 88% specificity in predicting chronic lung disease. We conclude that chest radiograph appearance at seven days of age is a sensitive and specific predictor of chronic lung disease and thus could be used to indicate the need for preventive therapy.

Blood pressure levels of preterm infants in the first year of life

Systolic blood pressure was measured in 36 infants with median gestational age of 29 weeks (range 24-35 weeks) and birth weight of 1160 g (range 642-1500 g). Measurements were made at 1, 6 and 12 weeks, and subsequently at 12-weekly intervals during the first year of life. No infant developed chronic lung disease. Systolic blood pressure increased over the first 24 weeks (p < 0.001) to a mean value of 95 mmHg, but did not change significantly over the next 24 weeks. These data provide a reference range of blood pressure levels during the first year of life for infants born at an early gestational age.

Hypertrophic obstructive cardiomyopathy as a side effect of dexamethasone treatment for bronchopulmonary dysplasia

We report three infants who developed hypertrophic obstructive cardiomyopathy during dexamethasone treatment for bronchopulmonary dysplasia. In all three infants, echocardiography had ruled out cardiac abnormalities prior to the dexamethasone course. The hypertrophic obstructive cardiomyopathy appeared and progressed during dexamethasone therapy and resolved completely after its cessation. This suggests a causative association between the hypertrophic obstructive cardiomyopathy and the exogenous glucocorticosteroid therapy. The mechanism of this dexamethasone-related hypertrophic obstructive cardiomyopathy is unclear. This complication may be encountered more frequently with the increasing use of dexamethasone in infants with bronchopulmonary dysplasia.

Effect of chronic lung disease on blood pressure levels at follow up

Thirteen preterm infants (median gestational age 28 weeks) who had developed neonatal chronic lung disease (CLD) and 13 gender- and gestational age-matched controls (without CLD) were prospectively followed. The infants were seen at monthly intervals for 6 months. At each attendance the infants were examined and their blood pressure (BP) measured using a noninvasive Doppler technique. No infant developed symptoms related to hypertension and there were no significant differences in their BP levels at follow up. Our results suggests significant BP elevation is uncommon following neonatal CLD.

Rapid increase of blood pressure in extremely low birth weight infants after a single dose of dexamethasone

Blood pressure was retrospectively studied in all 22 extremely low birth weight infants (ELBW) (birth weight median 720 g, range 450-1020 g) who were admitted between July 1989 and October 1991 and received dexamethasone on days 2-25 (median 10) because of bronchopulmonary dysplasia or since lung function had not improved after installation of bovine surfactant. The average blood pressure during the 4 h before dexamethasone increased significantly (median individual increase 8 mmHg, P = 0.0005) until 8-12h thereafter. In addition to the lung disease, ten infants showed severe arterial hypotension with prolonged capillary refilling time ( > 3s) and oliguria and needed continuous infusion of epinephrine to increase blood pressure and urinary flow after treatment with colloids, dopamine and dobutamine had proved ineffective. Epinephrine infusion could be stopped in eight infants 8 h after dexamethasone administration. In ELBW infants blood pressure rose 8-12 h after a single dose of 0.25 mg/kg dexamethasone. In ELBW infants suffering from arterial hypotension who do not respond to infusion of colloids and catecholamines, dexamethasone may represent a new therapeutic tool.

Neonatal blood pressure levels of preterm infants who did and did not develop chronic lung disease

The aim of this study was to assess if, in the neonatal period, there were differences in the blood pressure (BP) level of infants who did and did not develop chronic lung disease. If such differences were demonstrated to exist, we also hoped to determine influencing factors. Forty infants, consecutively admitted to our unit and who remained there throughout the neonatal period were studied. Twenty infants, median gestational age 29 weeks (range 27-32), did not develop CLD (non-CLD group) and 20 infants, median gestational age 26 weeks (range 24-32), developed CLD. Systolic BP was assessed using a non-invasive Doppler technique on day one and subsequently at weekly intervals. After day one and throughout the neonatal period BP levels, corrected for birthweight, were higher in the CLD group compared to the non-CLD group, by a mean of 5 mmHg. There was no significant difference between the numbers of infants in each group receiving theophylline or pancuronium. Significantly more infants in the CLD group had an umbilical catheter inserted and their catheters remained in situ significantly longer, a median of 8 days compared to a median of one day in the non-CLD group. We conclude that even in the neonatal period infants who develop CLD may have a modest elevation of BP, this is associated with prolonged umbilical arterial catheterisation. Our results, however, suggest that significant hypertension in infants who develop CLD, occurs after the neonatal period.