From the Guidelines
Maintaining adequate oxygen saturation (SpO2) in stroke patients is crucial for optimal brain tissue recovery, and the target SpO2 level should be 94% or higher, as recommended by the most recent guidelines 1.
Key Recommendations
- For patients with SpO2 below 94%, start with low-flow oxygen via nasal cannula at 2-4 liters per minute and titrate as needed, as suggested by the BTS guideline for oxygen use in adults in healthcare and emergency settings 1.
- For more severe hypoxemia, consider a simple face mask (5-10 L/min) or non-rebreather mask (10-15 L/min), and position the patient with head elevation at 30 degrees to optimize cerebral perfusion while reducing aspiration risk.
- Regular monitoring of SpO2 using pulse oximetry is essential, with more frequent checks during the acute phase, and oxygen saturation should be monitored at least every 4 hours throughout the day and night in patients with acute stroke, as recommended by the BTS guideline 1.
- Underlying causes of hypoxemia such as aspiration, pneumonia, or pulmonary edema should be promptly identified and treated, and patients with hypoxaemia post-stroke require medical review to establish and treat the cause, as emphasized by the BTS guideline 1.
Rationale
Maintaining adequate oxygenation is critical because the injured brain is particularly vulnerable to hypoxic damage, and even brief periods of hypoxemia can expand the ischemic penumbra (at-risk tissue surrounding the stroke core), worsening neurological outcomes, as highlighted by the American Heart Association/American Stroke Association guidelines 1. However, hyperoxia should also be avoided as it may increase free radical production and vasoconstriction, potentially harming vulnerable brain tissue, as noted by the BTS guideline for oxygen use in adults in healthcare and emergency settings 1. The American Academy of Neurology also affirms the value of maintaining adequate oxygen saturation in stroke patients, as stated in the guidelines for the early management of adults with ischemic stroke 1. Overall, the goal is to maintain a balance between adequate oxygenation and avoiding excessive supplemental oxygen, as recommended by the most recent and highest-quality studies 1.
From the Research
Maintaining SpO2 in Stroke Patients
To maintain SpO2 in stroke patients, several studies provide evidence-based guidelines:
- The American Heart Association/American Stroke Association (AHA/ASA) recommends maintaining SpO2 greater than 94% 2.
- A retrospective cohort study found that lower mean SpO2/FiO2 levels were strongly correlated with increasing mortality rates, suggesting the importance of maintaining adequate oxygenation in acute ischemic stroke patients 2.
- Another study found that supplemental oxygen treatment with a dose of 2 to 4 L/minute via nasal cannulae can increase oxygen saturation in patients with stroke, with a close dose-response relationship between the amount of oxygen given and the resultant changes in oxygen saturation 3.
Oxygen Therapy in Stroke
Oxygen therapy in stroke remains controversial, but emerging data suggests that hyperbaric and even normobaric oxygen therapy can be effective if used appropriately:
- A review article discusses the history, rationale, mechanisms of action, and adverse effects of hyperoxia, as well as the key results of previous hyperoxia studies, and the potential role of oxygen therapy in contemporary stroke treatment 4.
- Normobaric oxygen treatment (NBO) has shown protective effects on acute ischemic stroke animals and patients in pilot studies, but many critical scientific questions remain unclear, such as the therapeutic time window of NBO and the long-term effects 5.
Prehospital Supplemental Oxygen for Acute Stroke
Prehospital supplemental oxygen for acute stroke may be safe to evaluate prospectively:
- A retrospective analysis found that brief, early supplemental oxygen for stroke may be safe, with no significant increase in respiratory complications or difference in neurologic outcomes at discharge when controlling for confounders 6.
- The study suggests that prehospital supplemental oxygen may increase oxygenation to penumbral tissue and improve stroke outcomes, but further research is needed to confirm these findings 6.