Small doses of adrenaline contained in the local anaesthetic may result in prolonged increased cardiac function even after the vital signs return to normal

The effects of adrenaline contained in the local anaesthetic on vital signs have been reported under general anaesthesia or sedation. The ClearSight™ system measures cardiac parameters, including cardiac index, stroke volume, systemic vascular resistance index, continuous blood pressure, and heart rate, non-invasively and continuously. This study aimed to assess the effect of adrenaline contained in the local anaesthetic on cardiac function in conscious participants. Eight healthy adults were recruited for the study. Local anaesthesia was administered to the maxillary gingiva using 3.6 mL of 2% lidocaine with 1/80,000 of adrenaline (group AD) or without adrenaline (group non-AD) on separate days. The above listed cardiac parameters were recorded with the ClearSight™ system. All data were continuously monitored until these values returned to normal levels. The cardiac index and heart rate increased by 40% in group AD. Moreover, the cardiac index and systemic vascular resistance index in group AD required 50 min to recover to the pre-injection levels. Heart rate variations showed no intergroup differences, and variations in systolic continuous blood pressure persisted for only 30 min. The effect of anaesthetic injection containing adrenaline on cardiac function may persist even after the vital signs return to normal.