Nitrous Oxide Sedation Reduces Discomfort Caused by Atrial Defibrillation Shocks

Abstract

An implantable cardioverter defibrillator with atrial therapies (ICD-ATs) is an effective therapy to manage atrial tacharrhythmias. Acceptance of this therapy is limited by atrial shock related anxiety and discomfort. Inhaled nitrous oxide (N2O) is a potent sedative-analgesic-anxiolytic agent that may mitigate shock discomfort and anxiety and improve patient ICD-AT acceptance. ICD-AT patients with more than one ambulatory atrial shock within 12 months were enrolled and grouped by ICD-AT shock method; awake (n = 9) or asleep (n = 4) when ambulatory ICD-AT shock is delivered. A baseline questionnaire assessed the most recent ambulatory ICD-AT shock (3 +/- 3 months). A 65% N2O/35% O2 mixture was inhaled for 4 minutes followed by an ICD-AT test shock (18 +/- 8 J). The test shock mimicked the awake shock method. The test shock experience during N2O was evaluated via questionnaire immediately following and 24 hours after the shock. Shock related anxiety, intensity, pain, and discomfort were assessed using a ten-point rank scale. Baseline test shock scores were similar between the shock method groups. In the awake shock method group, N2O greatly reduced preshock anxiety by 48% (6.4 +/- 2.4 to 3.3 +/- 2.0, or), and shock related intensity (5.9 +/- 3.1 to 3.3 +/- 2.5), pain (5.0 +/- 2.6 to 2.0 +/- 2.1), and discomfort (5.6 +/- 2.4 to 1.3 +/- 1.4) from baseline values by 45%, 60%, and 78% (P < 0.05), respectively. The asleep shock method group reported no changes in shock related anxiety, intensity, pain, or discomfort. Atrial shock concern, assessed via a five-point rank scale (5 = extreme concern) was improved by N2O but only in the awake group (3.1 +/- 1.0 baseline to 1.6 +/- 0.5 N2O, P = 0.008). There were no adverse events with N2O and patients fully recovered within 5 minutes after N2O. In conclusion, 65% N2O greatly reduced shock related pain and discomfort, and significantly reduced atrial shock concern but only in the awake shock method group. The benefits of N2O therapy may expand the use and acceptability of ICD-AT therapy into a larger atrial fibrillation cohort.

A Randomized Clinical Trial of Continuous Flow Nitrous Oxide and Nalbuphine Infusion for Sedation of Patients During Radiofrequency Atrial Flutter Ablation

“…10 It has been shown that there was an association between pain catastrophizing and the increased slope in fear levels and pain during subsequent delivery of electric shocks. 23 In our study inhaled N 2 O was more efficient than Nalbuphine for relief not only of discomfort but also of anxiety. Because of its sedative, analgesic, and anxiolytic components, we thought that inhaled nitrous oxide could be useful during RF procedures.…”

“…Catastrophic thinking about pain is defined as an exaggerated negative orientation toward noxious stimuli 10 . It has been shown that there was an association between pain catastrophizing and the increased slope in fear levels and pain during subsequent delivery of electric shocks 23 . In our study inhaled N 2 O was more efficient than Nalbuphine for relief not only of discomfort but also of anxiety.…”

“…An inhaled nitrous oxide/oxygen mixture has been used for more than 100 years as a potent sedative‐analgesic‐anxiolytic agent, and has demonstrated its efficacy in various procedures associated with mild to moderate pain 11 , 22 . Although the mechanism of the analgesic effect of this gas has not been clearly defined, it has been proved effective for rapid pain relief during myocardial infarction, prehospital transcutaneous pacing and internal atrial cardioversion, with no significant adverse effects 8–10,23 …”

“…11,22 Although the mechanism of the analgesic effect of this gas has not been clearly defined, it has been proved effective for rapid pain relief during myocardial infarction, prehospital transcutaneous pacing and internal atrial cardioversion, with no significant adverse effects. [8][9][10]23 To our knowledge, the analgesic effects of nitrous oxide on pain due to RF applications have never been evaluated. Our study confirms that this agent is safe (fewer hemodynamic effects) and more effective than Nalbuphine infusion for relief of anxiety and discomfort during AF ablation.…”

Decreasing Pain and Anxiety Associated with Patient‐Activated Atrial Shock: A Placebo‐Controlled Study of Adjunctive Sedation with Oral Triazolam

“…The patient‐activated shock mode enables patients to treat their AF in a nonclinical setting; however, one potential disadvantage is shocks are administered without anesthesia or sedation. Repeated exposure to self‐administered shocks, which have been described as intense and painful, 1,2 may increase a patient's risk of developing anxiety and depression 3 . Thus, strategies are needed to improve the shock experience, alter the patient's memory of the shock, and potentially alleviate anticipatory anxiety for future shocks.…”