Abstract

ARRHYTHMIA FOLLOWING MIDAZOLAM: PHARMACOKINETICS OR PHARMACOGENOMICS?

Dr. Mitragotri Milon V., Dr. Kurdi Madhuri S., Dr. Yalagachin Gurushantappa H., Dr. Kallapur Basavaraj G

ABSTRACT

Midazolam is an imidazole-benzodiazepine compound used to allay anxiety, induce sedation and amnesia to patients undergoing surgeries under general anaesthesia. It is used occasionally prior to regional anaesthesia as an anxiolytic. We report a case of life threatening arrhythmia following midazolam premedication. A 65 year old otherwise healthy male with good effort tolerance and a pre -hypertensive blood pressure (BP) of 136/86mmHg was scheduled first on the list for fistulectomy under subarachnoid anaesthesia. Monitors were attached. (Pulse, non-invasive blood pressure and pulse oximetry) Intravenous (IV) infusion of ringer lactate(RL) was started. The initial heart rate and BP recorded were 76 per minute and 160/100mmHg respectively. Considering this BP to be due to anxiety, 1mg midazolam, freshly loaded, was given as a bolus intravenously. Patient became restless within a minute following it. Monitor displayed polymorphic ventricular tachycardia followed a few seconds later by bradycardia. (heart rate<40/min). The blood pressure fell to 70mmHg systolic. The patient then became apnoeic and semiconscious. Subsequently we administered 0.6mg atropine and 100% oxygen. The arrhythmia reversed and the patient regained consciousness immediately however the systolic blood pressure still recorded 90mmHg. IV fluid (RL) was rushed in (500ml) and the patient made a full recovery after 30minutes. Immediate 2D-ECHO and cardiologist opinion were sorted. They revealed no significant cardiac condition or on-going ischemia. Blood pressure readings read 150/96mmHg two hours following the event. It was then decided to go ahead with the planned surgery under spinal anaesthesia avoiding midazolam. The further course was uneventful. The patient was informed regarding the event and forewarned against any further exposure to benzodiazepines.

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