Effect of intermittent normobaric hyperoxia for treatment of neuropathic pain in Chinese patients with spinal cord injury

Abstract

Study design: Prospective, randomized and controlled study. Objectives: The aim of the study was to investigate the effect of intermittent normobaric hyperoxia (InHO) for treatment of neuropathic pain in patients with spinal cord injury (SCI). Setting: The First Affiliated Hospital of Nanhua University, Hengyang, Hunan Province, China. Methods: Patients with SCI from Hunan Province were recruited from the First Affiliated Hospital of Nanhua University. History, duration, localization and characteristics of pain were recorded. Visual analog scale (VAS), the Patient Global Impression of Change (PGIC) and Short Form-36 walk-wheel (SF-36ww) was used to investigate the effect of InHO. Patients were randomly assigned to study and control groups. In study group, patients were exposed to pure oxygen via non-rebreathing reservoir mask, which increased the provided oxygen at a rate of 7 l min − 1 for 1 or 4 h daily in 2 weeks. While in control group, patients breathed air via non-rebreathing reservoir mask at the same rate. Results: A total of 62 SCI patients with neuropathic pain were included in the study. The mean age of the patients was 36.85 ± 10.71 years. Out of 62 patients, 21 were tetraplegic and 41 were paraplegic. Overall, 14 patients had complete SCI while 48 patients had incomplete injuries. Three groups were similar with respect to age, gender, duration, smoker or not, level and severity of injury. In the 4 h per day InHO groups, a statistically significant reduction of the VAS values was observed (Po0.05). Significant difference was also found in SF-36ww pain scores and PGIC (Po0.05). However, such an effect was not evident in the control group. In one-third of those, the pain is severe. 3 Chronic neuropathic pain is often associated with conditions such as depression and anxiety, and strongly affects daily functioning and overall quality of life. 4,5 Many people with SCI rate chronic neuropathic pain as one of the most difficult problems to manage. Pharmacotherapy includes anticonvulsants, antidepressants, opioids and local anesthetics, 6,7 but responses vary and side effects limit compliance. Non-pharmacological treatments such as physical therapy, relaxation, hyperbaric oxygen and acupuncture are suggested. [8][9][10][11][12][13] Oxygen therapy has been clinically used for the treatment of chronic obstructive pulmonary disease and severe oxygen desaturation. Recent researches have reported that oxygen therapy appears to be effective in the pain management and show same effectiveness as hyperbaric oxygen. [14][15][16] Though studies have revealed the analgesic effect of hyperbaric oxygen in both rats and human with neuropathic pain, 13,17-19 costs and poor availability limit the use of hyperbaric oxygen. These prompt us to investigate the effect of intermittent normobaric hyperoxia (InHO) in the treatment of neuropathic pain.

Normobaric oxygen treatment for mild-to-moderate depression: a randomized, double-blind, proof-of-concept trial

“…It should also be studied with different oxygen doses (FiO 2 ). The oxygen fraction could perhaps be increased up to 45% without incurring significant safety risks 29 , 42 . In this regard, the currently available data do not enable drawing unequivocal conclusions regarding the long-term safety of normobaric oxygen treatment among non-hypoxic subjects 43 .…”

The CanPain SCI clinical practice guidelines for rehabilitation management of neuropathic pain after spinal cord injury: 2021 update

“…A single moderate quality RCT ( n = 62) found that a group receiving 4 h of pure oxygen had significant improvement in the mean visual analogue scale score at 14 days compared to a group receiving 4 h of air (control) and 3 h of air plus 1 h of pure oxygen (group A) [ 77 ]. No long-term effect (day 30 and day 60) was seen, although data was not provided.…”