Have you considered hyperventilation as the underlying cause?
I've seen a similar case: it can occur with a normal respiratory rate,
which is a bit confusing, but the characteristic physiological
findings are an increased tidal volume with increased alveolar
ventilation. The removal of larger-than-normal amounts of CO2 changes
the bicarbonate-carbonic acid ratio and the pH rises. Then a
compensatory metabolic acidosis develops. (renal - the kidneys reduce
the amount of acid they excrete).
Anyway, the long and short of it is that the subject develops signs of
tetany, which can be mistaken for fits, and then may go on to develop
grand or petit mal convulsions if the problem is not resolved. The
treatment is to get the patient to re-breathe their own exhaled air,
which controls the fits if this is the correct aetiology.
You would also expect to find an degree of alkalosis with hypokalenia
if this is the problem.
Nick Miller
London
On 02/02/2012, Wiedemann Larisa (RF4) BHR Hospitals
<[log in to unmask]> wrote:
> Dear all,
>
> I wonder if anyone could help...
>
> To keep it brief: 17y.o. female was admitted with fits and seizures,
> which started 1 week ago. (until then, she was perfectly fine). She is
> now on ITU on anti-epileptic therapy, but we are finding that these do
> very little to control her seizures.
>
> Biochemically of note is only her hypocalcaemia (Adj Ca 2.11mmol/L). CSF
> glucose/protein/lactate are normal. Micro results are still being
> processed.
>
> Could anyone suggest any metabolic causes for her presentation and
> current status?
>
> Any advice, as always, would be much appreciated by us, and the ITU
> team!
>
>
> Many thanks in advance,
>
> Larisa
>
>
>
> Larisa Wiedemann
>
> Pre-reg Clinical Scientist
> Biochemistry Department
> Queen's Hospital, Romford
> Essex, RM7 0AG
> Tel: 01708 435 506
> Fax: 01708 503 735
> DECT: 6194
>
>
> Barking, Havering & Redbridge University Hospitals NHS Trust: Most
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