Nitrous Oxide Analgesia

Inhaled nitrous oxide versus placebo as an analgesic and anxiolytic adjunct to peripheral intravenous cannulation

The objective was to determine whether an inhaled 50:50 mixture of nitrous oxide and oxygen (N(2)O/O(2)) provides significant pain and anxiety relief during intravenous cannulation in healthy adults. The study was conducted at the ED of a military teaching hospital. Participants included adult volunteers aged 18 to 50 years. Excluded were those with allergy to N(2)O, anemia, cardiac disease, pregnancy, asthma, or bone marrow disorder. A prospective, randomized, double-blind, placebo-controlled crossover design was used comparing a 50:50 mixture of N(2)O/O(2) versus O(2). After recording baseline nonhatched 100mm visual analog scales (VAS) for pain and anxiety, subjects inhaled gas 1 for 120 seconds, followed by antecubital intravenous cannulation, discontinuance of gas and VAS rating of procedural pain and anxiety. After 15 minutes, the experiment was repeated with gas 2. Ten subjects would detect a 12mm difference in pain or anxiety with a standard deviation of 10 mm, an alpha error under 0.05 and a power over 80%. Differences between VAS were compared by matched 2-tailed t-test. Eleven subjects were enrolled. One withdrew because of dizziness while inhaling gas (N(2)O). The 10 remaining subjects reported significantly less pain (N(2)O/O(2) 14.5mm, SD 18; O(2) 34.3mm, SD 23.4; P < .01) and anxiety (N(2)O/O(2) - 7.9mm, SD 7.8; O(2) 6.0mm, SD 11.6; P < .02) when inhaling N(2)O/O(2) than when inhaling O(2) alone. N(2)O/O(2) provided significant pain and anxiety reductions during intravenous cannulation. Some patients may experience adverse perceptions while using N(2)O, limiting its utility. Further studies defining the role of N(2)O as an anxiolytic agent, efficacy in actual patients, and cost comparisons with intravenous conscious analgesia/sedation, are warranted.

[Analgesia using a (50/50) mixture of nitrous oxide/oxygen in children]

Nitrous oxide is a gas that has been used to provide analgesia to patients for more than a century. Its modern use started in the late sixties when a mixture of 50% nitrous oxide/50% oxygen was prepared. Nitrous oxide/oxygen provides analgesia within 3 minutes of inhalation and this analgesic effect disappears in less than 4 minutes after cessation. Its administration is very easy and a complete or partial pain relief is observed in 75 to 81% of patients. The gas mixture has been found to be safe with few side effects and no significant adverse reactions. Diffusion hypoxia which could lead to hypoxemia was reported in 1955, but recent work does not confirm this complication. Nitrous oxide/oxygen mixture constitutes an excellent drug to control procedure-related pain in children. This articles describes the history, the pharmacology, and the clinical uses of nitrous oxide/oxygen in children.

Placebo and analgesic nitrous oxide for treatment of the alcohol withdrawal state

We present evidence that analgesic (as distinct from anaesthetic) nitrous oxide is superior to placebo in the treatment of the alcohol withdrawal state. 'Carbogen' as a placebo is as effective as oxygen or medical air. However, placebo alone offers a means of treating the alcohol withdrawal state with a minimum of pharmacological intervention. Analgesic nitrous oxide for those not responding to placebo is a very rapid, effective, and extremely safe treatment which also reduces the use of highly addictive sedative pharmacological agents. This therapy also provides a rapid method of screening those patients requiring intensive monitoring and treatment in hospital from those who might benefit from out-patient therapy alone.