Ahmed Ali D, Ahmed Ali I, Maheshwari C. The application of topical oxygen therapy in the treatment of diabetic foot ulcers; A systemic review. HPHR. 2022;67.
A total of 80 participants were involved in four studies which were having chronic nonhealing diabetic foot ulcers, aged 18 and above, having other comorbidities like hypertension, hyperlipidemia, heart diseases
Mean ulcer duration in the group using topical oxygen therapy ranges from 20 to 180 weeks while in the standard group it was 10-80 weeks. The location of ulcers included the dorsum of the foot, plantar surfaces of the foot, and toe digit.
All four studies using topical oxygen therapy resulted in wound healing and closure. The duration and application method of topical oxygen therapy in the treatment of diabetic foot ulcers is shown in table 1. Blackman et al assessed the recurrence of healed diabetic foot ulcers undergoing topical oxygen therapy while other studies did not mention it.  Driver et a mentioned that various pro-inflammatory cytokinin and proteases were also present in diabetic foot ulcer fluid which was not mentioned in other studies . Topical oxygen therapy has shown improved healing of diabetic foot ulcers.
Hayes et al. (2017) and Yu et al. (2016) found lower grade ulcers healed completely while higher grade ulcer’s reduction rate was 10% to 50% (p<0.05). Driver et al. observed that the topical oxygen therapy decreased the levels of pro-inflammatory cytokines and proteases in the ulcer fluid as compared to the control group in 2 weeks of duration.
Oxygen is required for all the stages of wound healing. oxygen level under the chronic wound and avascular wound is below 20mmHg and oxygen level below 20 mmHg impairs the wound healing. It is observed that a higher oxygen level of about 160 mmHg can cause fibroblast proliferation, activation of enzymes, and formation of proteins which enhances wound healing.  Chronic ulcers did not heal due to lack of oxygen  and other comorbidities increase the risk of it 
50 % of oxygen is required for the treatment of diabetic foot ulcers. The advantages of topical `oxygen therapy are that its cost-effective can be used in the home, and has fewer complications as compared to hyperbaric oxygen therapy . The mentioned studies showed that lower grade ulcers heal completely while higher grade ulcers showed a reduction in their size because higher grades were deep hence it was not possible for the deep wound to heal completely in a shorter time hence complete healing requires a longer time for the administration of topical oxygen therapy.
This review shows topical oxygen therapy can be used for the treatment of diabetic foot ulcers belonging to different grades. Lower-grade ulcers resolve completely while higher-grade ulcers show a reduction in size and for complete resolution, they need long topical oxygen therapy.