Case Report:
A 17-year-old male with a background of asthma took approximately 100g of Yew Tree seeds at around 22:30 one evening in an attempt to end his life. Assessment at the scene revealed bradycardia at 40 beats/minute, hypotension at around 60/30 mmHg and hypothermia. His Glasgow Coma Score (GCS) was 15/15. He was treated with IV Hartmann’s and 15L oxygen and brought to the nearby district general hospital where he was admitted at 03:08am.
On arrival to the Emergency Department his ECG showed a ventricular rhythm with a prolonged QT (QT 670ms / QTc 414ms) (Figure 1), so external pacing pads were applied in preparation. His initial venous blood gas showed a pH of 7.19 with a HCO3- of 24.8, BE of -4.8 and lactate of 3.5 (other values largely normal) (Table 1).
Initial peripheral infusions were started: magnesium 1g, sodium bicarbonate 1.26% at 83.3ml/hr, and Dobutamine 250mg in 500ml 5% dextrose at 20ml/hr. Dobutamine was chosen over adrenaline due to recommendations from Toxbase that adrenaline can worsen hypotension, possibly due to beta agonist effects (6). Dobutamine was rapidly titrated up to 30ml/hr but his bradycardia worsened to 20 beats/min and his GCS dropped. External pacing was commenced and restored circulation. Electrical capture was first obtained at 80mA, but this needed to be titrated up to 120mA to sustain mechanical capture.
Once central venous access was established, Isoprenaline 2mg in 500mls 5% glucose was started at 30mls/hr. This was increased over the next 5 minutes to 98ml/hr to allow for cessation of external pacing. Recommendations from Toxbase to aim for a pH of 7.5-7.55 (6) were noted, and three boluses of 8.4% sodium bicarbonate were given which resulted in a pH of 7.53 at 04:30, 82 minutes since first admission to hospital (Table 1).
On advice from UK NPIS, ECMO was contacted for consideration of transfer, but it was deemed to be too early at this stage of his treatment. The on-call cardiologist successfully inserted a right ventricular temporary pacing wire allowing Isoprenaline to be switched off, showing an underlying rhythm of asystole. Pacing capture was obtained at 0.5mA and the rate set to 80 beats/minute, giving a blood pressure of 100/48 mmHg.
The patient was admitted to the Intensive Care Unit where he received a Covid-19 throat swab which triggered an episode of emesis, in which he regurgitated a mixture of whole and semi-digested seeds. Over the next 12 hours he was treated with further sodium bicarbonate, potassium, magnesium and insulin therapy. Dobutamine was switched to an adrenaline infusion which was quickly titrated down and stopped. The threshold for his internal pacing wire increased to 1mA but held at that point. A bedside echocardiogram showed no obvious abnormalities besides bilateral pleural effusions.
28 hours after admission he switched into an unpaced broad complex 1st degree block rhythm with a QTc of 525ms. On day three his pacing wire was removed. He was discharged home on day six after seeing psychiatry, with further psychiatry follow-up and an outpatient echocardiogram arranged.