 |
 |
Refractory hypotension occurs when despite treatment with appropriate fluids and vasopressor therapy, low blood pressure and evidence of inadequate perfusion persist. Hypotension may be multifactorial, due to such underlying illnesses as poor cardiac output, sepsis, and hypovolemia. Relative adrenal insufficiency, a condition associated with an inadequate adrenal stress response to critical illness, may also contribute to the lack of response to routine therapy.1,2 In 2001, Seri and coworkers described the cardiovascular effects of administering physiologic doses of hydrocortisone, mimicking a stress response, to pre-term infants with refractory hypotension.3 Mean blood pressure increased significantly by 2 hours post-treatment, with continued improvement at 4 and 6 hours. Additionally, urine output improved, along with the decreased need for vasopressors. The use of hydrocortisone for the treatment of hypotension has since grown considerably.4
The physiologic mechanisms involved in the impact of corticosteroids on blood pressure are twofold.3 Acutely, steroids inhibit catecholamine metabolism and prevent reuptake of catecholamines, resulting in a prompt increase in blood pressure within hours of drug administration. In addition, steroids increase cytosolic calcium availability in vascular and smooth muscle cells, and prevent inflammatory vasodilation by inhibiting prostacyclin and nitric oxide production. Secondarily, glucocorticoids upregulate cardiovascular adrenergic receptors through increased gene expression, resulting in a more sustained response to treatment. This is particularly advantageous, as the attenuated cardiovascular responsiveness to catecholamines in severe disease states may be related to downregulation of the adrenergic receptors and is reversible through the induction of gene expression by glucocorticoids.
Although relative adrenal insufficiency may play a role in the refractory hypotension observed in some neonates, defining a population that could most benefit from hydrocortisone therapy has been challenging.5 Cortisol levels are low in utero6 and can remain low postnatally without any undue effects in pre-term infants.7 In the studies by Masumoto et al. and Baker et al., reviewed in this newsletter, low cortisol values were not helpful markers for defining those infants most likely to benefit from hydrocortisone therapy. Regardless of the etiology of the hypotension or baseline cortisol concentrations, those infants who do not respond to volume administration and high-dose vasopressors can benefit from the use of hydrocortisone because of its regulatory effects on the cardiovascular system.
As hydrocortisone use began to increase, evidence also mounted
for the adverse neurodevelopmental consequences associated
with neonatal exposure to another steroid, dexamethasone.
A 2002 American Academy of Pediatrics statement advocated
limiting corticosteroid use in neonates, in light of an increased
incidence of cerebral palsy reported following dexamethasone
exposure.8 In neuronal cell culture, stimulation
of glucocorticoid receptors promotes apoptosis, whereas mineralocorticoid
receptors inhibit apoptosis. Dexamethasone is entirely glucocorticoid
in its effects, with high doses suppressing innate adrenal
mineralocorticoid production.9
Hydrocortisone administered in stress physiologic doses provides
a balance of glucocorticoid and mineralocorticoid activity.
Encouraging data are emerging that support this in vitro observation
in clinical studies. Studies by Watterberg et al. and Rademaker
et al., discussed in this newsletter, present long-term follow-up
on hydrocortisone-exposed infants with reassuring results,
although neither study used hydrocortisone specifically for
the treatment of hypotension.
Hydrocortisone is thus helpful for treating neonates in shock, particularly when hypotension persists despite fluid and vasopressor therapies. Although dosing is aimed at providing levels necessary during physiologic stress, it varies from 0.5 to 6 mg/kg/day (approximately 10 to 60 mg/m2), and the length of treatment and need for ongoing maintenance therapy are still not well understood.
.
Commentary References
| 1. |
Watterberg KL, Scott SM.
Evidence of early adrenal insufficiency in babies who develop bronchopulmonary dysplasia. Pediatrics. 1995;95(1):120-125.
|
 |
| 2. |
Huysman MW, Hokken-Koelega AC, De Ridder MA, Sauer PJ.
Adrenal function in sick very pre-term infants. Pediatr Res. 2000;48(5):629-633. |
 |
| 3. |
Seri I, Tan R, Evans J.
Cardiovascular effects of hydrocortisone in pre-term infants with pressor-resistant hypotension. Pediatrics. 2001;107(5):1070-1074. |
 |
| 4. |
Finer NN, Powers RJ, Ou CH, Durand D, Wirtschafter D, Gould JB, et al.
Prospective evaluation of postnatal steroid administration: a 1-year experience from the California Perinatal Quality Care Collaborative. Pediatrics. 2006;117(3):704-713. |
 |
| 5. |
Aucott SW, Watterberg KL, Shaffer ML, Donohue PK; PROPHET Study Group. Do cortisol concentrations predict short-term outcomes in extremely low birth weight infants? Pediatrics.
. 2008;122(4):775-781.
|
 |
| 6. |
Bolt RJ, van Weissenbruch MM, Popp-Snijders C, Sweep CG, Lafeber HN, Delemarre-van de Waal HA.
Fetal growth and the function of the adrenal cortex in pre-term infants. J Clin Endocrinol Metab.
2002;87(3):1194-1199. |
 |
| 7. |
al Saedi S, Dean H, Dent W, Cronin C. Reference ranges for serum cortisol and 17-hydroxyprogesterone levels in pre-term infants. J Pediatr.
1995;126(6):985-987. |
 |
| 8. |
American Academy of Pediatrics Committee on Fetus and Newborn.
Postnatal corticosteroids to treat or prevent chronic lung disease in pre-term infants. Pediatrics. 2002;109(2):330-338. |
 |
| 9. |
Almeida OF, Condé GL, Crochemore C, Demeneix BA, Fischer D, Hassan AH, et al.
Subtle shifts in the ratio between pro- and antiapoptotic molecules after activation of corticosteroid receptors decide neuronal fate. FASEB J. 2000;14(5):779-790 |
 |
|
|
|