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Sat Jan 31 11:06:35 GMT 2009

Cardiac uncoupling is, I believe, as sign of a sick heart, and not something
you can treat per se.  Some drugs may exacerbate the uncoupling, but I doubt
you can fix uncoupling per se.
While the adrenergic explanations of the beta-blockers are nice and simple I
expect their benefit will have a lot to do with their anti-inflammatory
effects, and also with their effect on non-cerebral outcomes (esp. cardiac
in more elderly patients).  Like a lot of the new thinking appearing in
trauma, there's some very tantalising hypotheses being derived from basic
retrospective studies, but we need more mechanistic and prospective work to
pick apart the signals and understand both the mechanisms of action and the
patients who may benefit.

Karim

2009/1/30 Errington Thompson <errington at erringtonthompson.com>

> Thanks.  I was at Washington University in the mid-90's when Tim Buchman
> and
> others were talking about heart rate variability.  I remember that many of
> us asked the question how do you increase HR variability and does that
> improve survival?  It would seem to me that beta blockers would decrease HR
> variability as it slows the HR.
>
> Clearly I'm going to have to do more reading.
>
> E
>
> Errington C. Thompson, MD
> Trauma/Surgical Critical Care
> Talk Show Host - WPEK
> www.whereistheoutrage.net
> Asheville, NC
>
> -----Original Message-----
> From: trauma-list-bounces at trauma.org [mailto:
> trauma-list-bounces at trauma.org]
> On Behalf Of Teperman, Sheldon
> Sent: Friday, January 30, 2009 10:07 AM
> To: 'trauma-list at trauma.org'
> Subject: RE: trauma-list Digest, Vol 67, Issue 44-- Beta Blockers and Head
> injury
>
>
>  Karim.  Was not sure you got my response on Beta blockers,  someone in the
> last volume was asking.  Sheldon
>
> -----Original Message-----
> From: Teperman, Sheldon
> Sent: Wednesday, January 28, 2009 12:47 PM
> To: 'trauma-list at trauma.org'
> Subject: RE: trauma-list Digest, Vol 67, Issue 44-- Betal Blockers and Head
> injury
>
>  We do use Beta blockers extensively in the Head injured PTs. in our SCICU.
> I have appended the most relevant Abstract- from our Colleagues at
> Vanderbilt. We have observed for years that there is a group of head injury
> Pts, almost all of them "Severe", that have a certain kind of run away and
> persistent Tachycardia- It has none of the usual explanations ( i.e. fever,
> pain ect). The Vanderbilt group attempts to further clarify the problem and
> tries to bring into focus the term "uncoupling" and indicating that in pts
> that loose the normal variability of heart rate( and inherently
> tachycardia)-there is an excess mortality. Beta blockers would see to have
> some beneficial effect here....
>        We have also heard the following phrasing, " its like your Pt is
> running a Marathon for no reason, Hanging out with a heart rate of 120 to
> 150." At the extremes it is unlikely that the physiologic, metabolic and
> nutritional consequences of that are healthy. The literature seems to be
> headed in that direction of agreeing that trimming that tachycardia and
> stopping the Marathon is a good thing. We have frequently talked about
> studying those Metabolic derangements and the response to Beta blockers,
> but
> alas it never got off the ground.  Would be a good thing to do.   Shel
>
>  Oh and one more, thought- Not having to see a monitor showing a HR of 150
> on your pt during rounds- day after day, well that has a certain
> therapeutic
> effect for....The Doctor and the Nurse...
>
>
> : J Trauma. 2007 Sep;63(3):503-10; discussion 510-1. Links Beta-blocker
> exposure in patients with severe traumatic brain injury (TBI) and cardiac
> uncoupling.Riordan WP Jr, Cotton BA, Norris PR, Waitman LR, Jenkins JM,
> Morris JA Jr.
> Departments of Surgery, Vanderbilt University Medical Center, Nashville,
> Tennessee 37212, USA. william.riordan at vanderbilt.edu
>
> BACKGROUND: Cardiac uncoupling and reduced heart rate (HR) variability are
> associated with increased mortality after severe traumatic brain injury
> (TBI). Recent data has shown beta-blocker (betaB) exposure is associated
> with improved survival in this patient population. The purpose of the
> present study was to evaluate the effect of betaB exposure on the mortality
> risk of patients with severe TBI and early cardiac uncoupling. METHODS:
> From
> December 2000 to October 2005, 4,116 patients were admitted to the trauma
> intensive care unit. Four hundred forty-six patients (12%) had head
> Abbreviated Injury Scale score >/= 5 without neck injury and had continuous
> HR data for the first 24 hours. One hundred forty-one patients (29%)
> received betaB. Cardiac uncoupling was calculated as the percent of time
> that 5-minute HR standard deviation was between 0.3 bpm and 0.6 bpm on
> postinjury day 1. RESULTS: A relationship between betaB and survival was
> observed when the population was considered
>  irrespective of length of stay or betaB start time (p < 0.001). Cardiac
> uncoupling appears to stratify patients into groups who might receive
> additional benefit from betaB, and identifies patients with increasing
> mortality. However, the association of betaB with survival was attenuated
> when analyses accounted for selection bias in betaB administration.
> CONCLUSIONS: betaB exposure was associated with reduced mortality among
> patients with severe TBI. Though loss of HR variability has previously been
> associated with an increase in mortality, betaB exposure appears to be
> associated with increased survival across all stratifications of cardiac
> uncoupling.
>
> PMID: 18073593 [PubMed - indexed for MEDLINE]
>
>
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trauma-list Digest, Vol 67, Issue 44-- Beta Blockers and Head injury