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External DC cardioversion is a commonly used method of terminating atrial arrhythmias. The chance of procedural success is inversely related to the duration of the arrhythmia. Rapid patient turnover is therefore of importance in managing this condition. In many hospitals, the procedure is carried out under general anaesthesia, necessitating the presence of anaesthetic as well as medical staff. Frequently, it may be difficult to coordinate the availability of the two teams, causing delays to each patient, waste of staff time, and an inefficient service. We report our experience with physician administered sedation using intravenous diazepam during DC cardioversion, without anaesthetic support. We assessed the safety, efficacy, and cost effectiveness of this approach.
One hundred and forty one patients (63% men, age (SD) 69 (11.3) years) undergoing DC cardioversion in our coronary care unit were studied over 15 months; 119 (84%) had atrial fibrillation (AF), 22 (16%) had atrial flutter. Underlying aetiology is shown in table 1. Sedation and cardioversion were carried out on each occasion by one physician and one nurse, both experienced at cardioversion and trained in advanced life support. Full resuscitation equipment, including facilities for assisted ventilation, was immediately available. Oxygen was administered continuously via a facemask.
Patients were initially given 5–10 mg diazepam intravenously, with further aliquots of 5–10 mg each minute, until adequate sedation was achieved, characterised by somnolence and loss of the eyelid reflexes. Additional agents were used at the doctors' discretion. DC shock was delivered in the antero-apical position followed by antero-posterior if unsuccessful. An initial energy of 200 J followed by 360 J in each position with the use of atropine was recommended.
Following cardioversion, patients were monitored for three hours and received oxygen until fully awake. Arterial oxygen saturation level was continuously monitored using a finger probe and blood pressure checked using a brachial cuff. The amount of sedation used, the number and energy of shocks, and the outcome were recorded. Any complications were noted. Patients went home between 4–6 hours after the procedure. Before discharge, patients were asked to complete a short questionnaire. This assessed any recollection of the procedure; recollection of pain; any other recollection; satisfaction with the procedure. Data are presented as mean (SD).
Cardioversion was successful in 82% (79% for AF, 100% for atrial flutter). On average 1.9 shocks were given, delivering 493 (361) J. The median successful energy level was 200 J. Sinus rhythm was achieved after one shock in 67 patients, two shocks in 26, three shocks in 18, and after four shocks in five patients.
The dose of diazepam ranged from 5–100 mg (27.2 (17.8) mg) and correlated inversely with age (r = −0.44, p < 0.001, Pearson's test). Men required a significantly higher dose than women (31.1 (19.7) mg v 20.4 (11.0) mg, p < 0.001, Student's t test).
Diazepam alone provided adequate sedation in 97%. Four patients (all male) required additional sedation or analgesia. One received midazolam 10 mg after 90 mg diazepam. Two received pethidine 50 mg: one requested additional analgesia, the other received 80 mg diazepam and required four cardioversion attempts. A 65 year old received diamorphine 5 mg in addition to diazepam 80 mg. Despite this, he later recalled a “thump” in his chest but no discomfort. None of these patients, nor the patient who received 100 mg diazepam, suffered any complications.
Respiratory depression occurred in two patients, both female, aged 66 years and 88 years, who each received 20 mg diazepam. In both cases, the arterial oxygen saturation dropped below 90% and responded rapidly to administration of flumazenil 500 μg intravenously. No patient required assisted ventilation. In no instance was the presence of an anaesthetist required.
One patient suffered a transient ischaemic attack. This was a 54 year old man in atrial flutter for five days. He had undergone coronary bypass surgery three weeks before and was on aspirin but not anticoagulated.
There were no instances of sustained ventricular arrhythmia or hypotension requiring treatment.
A total of 131 patients (93%) fully completed the questionnaire. No patient recalled any pain. Two (1.5%) recalled a “thump” and a “sensation” in the chest but no discomfort. All patients were satisfied with the procedure and were discharged home the same day.
Our findings are comparable with those of studies reported in the early days of DC cardioversion, which suggested that diazepam produced effective sedation during DC cardioversion, with few adverse effects.1-3 Respiratory depression is far less common with diazepam than with general anaesthetic agents and occurred in only 1.4% of our patients. Diazepam has been found to produce no significant changes in the arterial Po 2 or Pco 2 during cardioversion.2Flumazenil, a benzodiazepine antagonist, is effective at reversing deep sedation in cardioversion patients.4
An important advantage of physician administered sedation is the relative ease of organising procedures. When general anaesthesia is employed, it is often a member of the on-call anaesthetic team who is required to be present. However, the commitments of on-call staff are often such that elective procedures, such as DC cardioversion, are unacceptably delayed or even cancelled. The impact of sedation on both staff and economic resources was recently studied prospectively in 59 patients undergoing DC cardioversion.5 Subjects were given either a general anaesthetic by an anaesthetist or midazolam plus morphine by a physician. As well as proving equally safe and effective, sedation by physician was more convenient and considerably cheaper.
We calculated similar cost savings with our approach. At our hospital, the cost of DC cardioversion per procedure is contracted at £337 under general anaesthesia and £265 under sedation. With our current procedure rate of around 350 per year, this translates into an annual cost saving of over £25 000.
In summary, we have found that sedation by physician with diazepam for DC cardioversion is both safe and effective, providing excellent patient satisfaction and flexibility in arranging procedures. Staff efficiency and patient turnover are improved and costs greatly reduced. Sedation should be administered by staff experienced in its use, in an area where assisted ventilation may be carried out and full resuscitation facilities (including flumazenil) are available.