Spotlight on Research

Can lactate help to differentiate epileptic from non-epileptic seizures?

Emergency medical services are frequently responding to care for younger children suffering from a convulsive disorder, but decision-making can be challenging in the out-of-hospital environment. Decision-making requires the clinician to differentiate between an epileptic and a non-epileptic seizure, but that differentiation in an out-of-hospital setting may be difficult.

An accurate recall of the event is key to determining its nature but parents who have seen their child having a seizure are often terrified and their emotional state can interfere with the memory of the episode. Misleading observations may lead to unnecessary investigations and inappropriate treatment. Recognising that an electroencephalogram (EEG) is useful in hospital but not available in an ambulance, the authors of this paper sought to establish whether an alternative marker may support differentiation between epileptic and non-epileptic seizures. The marker of choice was lactate.

The primary objective was to study the association between the value of capillary lactate measured by a mobile paediatric intensive care unit (MPICU) after a paroxysmal event to differentiate epileptic seizure from febrile seizure and non-epileptic events. The secondary objective was to assess the other factors associated with prehospital capillary lactate concentrations.

There were 102 patients aged >1 month to <18 years included in the study. Each had lactate concentrations taken in a prehospital setting within 2 hours of the event. Results were analysed based on the final diagnosis from the hospital report: 53 (52%) patients had epileptic seizures, 41 (40%) had febrile seizures, and 8 (8%) had syncope or psychogenic non-epileptic seizures (PNES). Capillary lactate in patients with a final diagnosis of epileptic seizure was significantly increased compared with concentrations in patients with febrile seizure (p<0.0007) and in patients with syncope or PNES (p<0.0204). Prehospital capillary lactate concentrations >3.9 mmol/litre seemed to be a fair biomarker for epileptic seizure.

Methoxyflurane—difficult to spell, easy to inhale!

Pain relief in the prehospital setting may be inadequate for several reasons, including the lack of availability of suitable analgesics. Inhaled methoxyflurane has been used by paramedics in Australia for decades but there is limited experience of its use in Europe. The authors of this observational study aimed to determine the effectiveness of methoxyflurane as a sole analgesic, measured as the proportion of cases in which sufficient analgesia was achieved by methoxyflurane alone. Secondary endpoints such as user friendliness (for EMS personnel), time to pain relief, vital parameters, side effects, and satisfaction of patients were also measured.

Methoxyflurane was administered by emergency physicians in Austria as an alternative to intravenous analgesia to trauma patients aged >18 years old who had moderate-to-severe pain (NRS ≥4), were fully conscious, able to give informed consent, and had no impairment of vital functions. There were 107 patients included in the analysis with a median NRS pain score of 8.0 on arrival of the attending physician. At 15 minutes, the median NRS fell to 4.0. The median time to reduction of pain was 3 minutes with no statistical difference between the sexes. Sufficient analgesia was achieved using methoxyflurane alone in 67 patients (61.5%); 41 (37.6%) patients needed supplementary analgesia and one had inadequate analgesia with methoxyflurane but received no supplementary analgesia. Notably, a significant improvement in analgesia was recorded with increasing patient age.

Side effects were frequent but mild, and user satisfaction was scored as very good when pain relief was sufficient, but fair in patients without benefit. Physician reports on user friendliness were very good but technical issues such as fluid leaking from the inhaler were reported in 16% of cases. No adverse events occurred and vital parameters remained stable. The study suggests some utility in methoxyflurane for paramedics and it may be helpful as an addition to the current array of analgesics.

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