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Tuesday, March 2, 2010

Hyper-what? In the NICU!

Neonate I get consulted a lot for neonatal hypertension.

In actuality, most cases I see are not really neonates but premature infants who are nearing their due dates. They often have chronic lung problems or other major health issues and a history of umbilical vessel catheterizations.

Because of issues with measuring and confirming blood pressures in this age group, our practice is to rely on the systolic measurement (SBp). A variety of studies address normal blood pressure in neonates, with most showing a value of approximately 110 mmHg as the 95th percentile after the first 2 weeks of life. Elevated blood pressures in these infants rarely cause detectable end-organ damage such as cardiac enlargement. Virtually all infants with blood pressures above the 95th percentile have complete resolution of this condition by 2 years of age. Risks and benefits of treatment or non-treatment remain unclear.

Values repeated greater than the 95th percentile for age warrant a work-up that includes estimated glomerular filtration rate via serum creatinine measurement; a urinalysis and culture; and a renal ultrasound with doppler bloodflow studies. Echocardiogram may show a cause for the SBp elevation, or may indicate end-organ damage. We rarely find a secondary cause for the blood pressure elevation. 

The question remains whether to treat or not to treat. No studies provide concrete evidence of benefit of treatment. Major risks of medications include dropping the blood pressure too low. Occasional reports of death, heart failure, and encephalopathy associated with high blood pressure warrant careful consideration of treatment benefits, though.

About 10 years ago, I decided to make a “rule” about how I would handle these babies. SBp of 110 seemed the critical value. Since most of these infants were still in neonatal units, we generally had access to multiple readings over several days. If the SBp were greater than 110 on more than half of the readings, treatment with an angiotensin-coverting enzyme inhibitor was recommended. Otherwise, ongoing observation of SBp occurred.

My last call week included several infants with SBp elevations, so I pulled more recent articles on this topic. While no definitive randomized trials or other evidence-based studies have been published, the overall recommendations remain consistent with those I created a decade ago, as far as I can tell.

I feel better now. But I wish we knew more.

References:

Arch Dis Child Fetal Neonatal Ed 2002;86:F78-F81 doi:10.1136/fn.86.2.F78

Pediatr Nephrol. 2009 Jan;24(1):141-6. Epub 2008 Jul 9 doi:10.1007/s00467-008-0916-9

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2 comments:

  1. I am interested in the "I decided to make a rule..." part of it. Can you tell us more about how you made this decision?

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  2. After reviewing the available studies and concluding there was no evidence to support any particular course of action, I took what I knew to develop something that "seemed" to be a rational course. I wanted to come up with a personal approach that was more "standard" than whatever I was thinking or feeling that day. I was looking for consistency in my own practice, even though no clear-cut approach could be gleaned from the literature.
    SBp 110 was a reasonable cut-off (although 113 was suggested by some studies; like we can really distinguish 110 from 113 most of the time). And if the kiddo was greater than that at least half the time (and this was usually based on 7-10 days worth of readings), they probably had real hypertension and were at greatest risk for end-organ damage. There was also, in my mind, less risk of problematic hypotension from the treatment in that situation.
    And 10 years later, there are more descriptive studies, but no evidence about the pros and cons of treatment approaches. Given that this condition usually resolves spontaneously, often in 3 or 4 months, it is going to be difficult to come up with evidence supporting much of anything.
    Physicians often come up with this sort of rule of thumb when evidence is lacking - and sometimes in the face of evidence.

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