<p>A single session of hyperbaric oxygen therapy demonstrates acute and long-lasting neuroplasticity effects in humans: a replicated, randomized controlled clinical trial</p>

Abstract

Purpose Animal studies have demonstrated anti-inflammatory, and anti-nociceptive properties of hyperbaric oxygen therapy (HBOT). However, physiological data are scarce in humans. In a recent experimental study, the authors used the burn injury (BI) model observing a decrease in secondary hyperalgesia areas (SHA) in the HBOT-group compared to a control-group. Surprisingly, a long-lasting neuroplasticity effect mitigating the BI-induced SHA-response was seen in the HBOT-preconditioned group. The objective of the present study, therefore, was to confirm our previous findings using an examiner-blinded, block-randomized, controlled, crossover study design. Patients and methods Nineteen healthy subjects attended two BI-sessions with an inter-session interval of ≥28 days. The BIs were induced on the lower legs by a contact thermode (12.5 cm 2 , 47C°, 420 s). The subjects were block-randomized to receive HBOT (2.4 ATA, 100% O 2 , 90 min) or ambient conditions ([AC]; 1 ATA, 21% O 2 ), dividing cohorts equally into two sequence allocations: HBOT-AC or AC-HBOT. All sensory assessments performed during baseline, BI, and post-intervention phases were at homologous time points irrespective of sequence allocation. The primary outcome was SHA, comparing interventions and sequence allocations. Results Data are mean (95% CI). During HBOT-sessions a mitigating effect on SHA was demonstrated compared to AC-sessions, ie, 18.8 (10.5–27.0) cm 2 vs 32.0 (20.1–43.9) cm 2 ( P =0.021), respectively. In subjects allocated to the sequence AC-HBOT a significantly larger mean difference in SHA in the AC-session vs the HBOT-session was seen 25.0 (5.4–44.7) cm 2 ( P =0.019). In subjects allocated to the reverse sequence, HBOT-AC, no difference in SHA between sessions was observed ( P =0.55), confirming a preconditioning, long-lasting (≥28 days) effect of HBOT. Conclusion Our data demonstrate that a single HBOT-session compared to control is associated with both acute and long-lasting mitigating effects on BI-induced SHA, confirming central anti-inflammatory, neuroplasticity effects of hyperbaric oxygen therapy.

The History and Development of Hyperbaric Oxygenation (HBO) in Thermal Burn Injury

“…On the contrary, only one out of four human volunteers [ 13 ] and two out of 11 clinical studies were prospectively randomized [ 24 , 25 ]. Three volunteer studies [ 26 , 27 , 28 ] used a crossover design, three clinical studies included matched pairs [ 29 , 30 , 31 ], four non-randomized controls [ 12 , 32 , 33 , 34 ] and two were case series [ 35 , 36 ].…”

“…Wahl, from the same group, used an identical setup in 2019. After a single HBO treatment, an immediate mitigating effect on hyperalgesia followed by a long-lasting reduction of pain sensitivity surrounding the injured area was documented [ 28 ].…”

“…Recent investigations focusing on postburn pain documented marked reduction of sensitation that could be induced by even one single HBO treatment session [ 27 , 28 , 34 , 67 , 68 ].…”

Methodology and applicability of the human contact burn injury model: A systematic review

“…Contact burn injury methodology. Heating paradigm: The most common heating paradigm was 420 s at 47˚C (40/64 [63%] studies; Fig 2) [1,2,5,6,10,[12][13][14][15][16]18,20,21,27,29,[32][33][34][36][37][38][39][41][42][43][44]46,[48][49][50]53,[55][56][57][58][59][60][61][62]64]. One study applied a longer exposure time in a control group than in the intervention group (420 s vs. 360 s both at 50˚C) [7], while another study applied a PLOS ONE � not assessed at baseline.…”

“…higher temperature during a preliminary trial compared to the intervention trial (300 s at 49˚C vs. 300 s at 47˚C) [11]. Contact thermode surface area: The most commonly applied active thermode surface area were 12.5 cm 2 (41/64 [64%] studies) [1,5,6,10,12,13,16,[18][19][20][21]29,[32][33][34][36][37][38][39][41][42][43][44][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61][62]64], 3.75 cm 2 (10/64 [16%] studies) [7,[22][23][24][25][26]30,…”