Fig. 1From: A fixed nitrous oxide/oxygen mixture as an analgesic for patients with postherpetic neuralgia: study protocol for a randomized controlled trialStudy design framework. PHN postherpetic neuralgia, NRS numerical rating scale, SpO2 percutaneous oxygen saturation, HR heart rate, BP blood pressure, RTO routine treatment plus oxygen, RTN routine treatment plus nitrous oxide/oxygen mixtureBack to article page