Prehospital conversion of Paroxysmal Supraventricular Tachycardia using Modified Valsalva Manoeuvre: A Case Report

The modified valsalva manoeuvre (MVM) has never before been performed in the prehospital setting by the Hamad Medical Corporation Ambulance Service (HMCAS) in the State of Qatar. Currently, their clinical practice guidelines (CPG) prescribe the vagal manoeuvre (VM) using a 10cc syringe as first line therapy for patients presenting with symptomatic paroxysmal supraventricular tachycardia (pSVT). The effectiveness of the MVM in terminating pSVT compared to the traditional VM is well documented, although prehospital studies in this area are lacking. In this case, a generally healthy 47-year-old male migrant worker presented with new-onset symptomatic pSVT successfully terminated by a MVM after initial failed attempts of a traditional VM. The MVM is a postural technique performed by placing the patient in a semi-recumbent position initially. The patient is then encouraged to blow into a manometer to achieve a 40 mmHg intrathoracic pressure for 15 seconds. Once the 40 mmHg intrathoracic pressure is achieved, the patient is repositioned supine and their legs are raised passively to 45 degrees for 15 seconds. The patient is then returned to the semi-recumbent position for 45 seconds before cardiac rhythm re-assessment. The MVM has shown to have an increased termination rate of pSVT with no documented serious adverse events. The MVM can be performed in a time effective manner, the procedure is cost effective as intravenous cannulation is not required and the prevention of adenosine associated transient asystole is prevented. It is recommended that ambulance services consider the inclusion of the MVM in their CPGs for the treatment of new-onset pSVT.