Normobaric Oxygen Therapy in Acute Stroke: A Systematic Review and Meta-Analysis

Abstract

Purpose: Normobaric oxygen (NBO) is potentially a readily accessible neuroprotective therapy. We undertook a systematic review to assess NBO in acute stroke. Methods: MEDLINE, EMBASE, and CENTRAL databases were searched to December 2020. Randomized controlled trials of NBO administered <7 days after stroke to normoxic patients with no other indication for oxygen were identified. Data on early neurological recovery; functional outcome; mortality; oxygen saturation, and imaging markers were collected. Findings: Fifteen publications involving 12 cohorts and 9,255 participants were identified. One study with 8,003 participants had low risk of bias, but the designs of smaller trials had limitations. Ninety-seven per cent of participants were in studies of low-flow oxygen (≤4 L/min). 82.8% had ischaemic stroke. Median time to treatment was 19.3 h. Meta-analysis demonstrated no significant effect on: reduction in National Institutes of Health Stroke Scale at 7 days in all stroke or ischaemic stroke only (mean difference −0.16 [−1.11 to 0.80] and −0.73 [−3.54 to 2.08], respectively); modified Rankin scale at 3–6 months of follow-up (combined standardized mean difference [SMD] −0.08 [−0.38 to 0.22]; 3 months SMD −0.01 [−0.03 to 0.029]; 6-month SMD −0.20 [−1.49 to 1.09]), or mortality (odds ratio 1.15 [0.87–1.53]). Discussion: The majority of patients were administered low-flow oxygen in the sub-acute phase. Intervention strategies targeted at modification of early tissue survival (higher oxygen delivery and administration at early time points when significant volumes of viable tissue persist) have not been tested adequately. Conclusion: Studies of NBO have shown no significant effect on early neurological recovery, functional outcome, or mortality in acute stroke. Oxygen has been predominantly low-flow and commenced in the sub-acute phase.

Anaesthetic and peri-operative management for thrombectomy procedures in stroke patients

“…While several randomized controlled studies have assessed the interest of systematic oxygen administration in patients presenting with ischemic CVA, none of them have shown this to be effective with regard to neurological evolution at 3 months [30][31][32]. That much said, none of the studies have dealt specifically with patients having undergone thrombectomy, and the rate of recanalization among these patients has not been reported.…”

The BE COOL Treatments (Batroxobin, oxygEn, Conditioning, and cOOLing): Emerging Adjunct Therapies for Ischemic Cerebrovascular Disease

“…Most studies concluded that NBO intervention initiated within 12 h of stroke onset resulted in a better prognosis. Oxygen flow velocity in these studies was usually set as 10 L/min and maintained for more than 12 h. A systematic review by Mahood et al, which included fifteen articles on NBO therapy for AIS patients, comprehensively reviewed the outcomes of mortality, symptom relief, neurological function, and neuroimaging improvements in AIS patients after NBO intervention [ 48 ]. Although the difference between the NBO group and the control group was not considered significant due to the small sample size and heterogeneity of NBO intervention modes, the authors observed a neuroprotective trend associated with NBO treatment.…”

Association between nocturnal oxygen desaturation and ischaemic stroke outcomes

“…In summary, in normoxemic AIS (as well as myocardial infarction) patients, the prophylactic use of low-dose oxygen supplementation did not significantly affect all-cause mortality or rehospitalisation and early neurological recovery or functional outcome measures, such as early disability or mortality. Therefore, these findings do not support lowdose oxygen supplementation in nonhypoxic patients with AIS [4,[13][14][15].…”

“…Interestingly, studies on normobaric oxygen therapy and hypoxemia measured by pulse oximetry have predicted AIS outcomes differentially [12]. A recent systematic review and meta-analysis found no effect of normobaric oxygen therapy on outcomes, including early neurological improvement, functional outcomes at 3-6 months, or the mortality rate [13].…”