|
Author |
Andrew Pauls |
Date |
2020-10-05 |
|
Reviewer |
Jennie Helmer |
Edited |
2020-10-22 |
You and your partner arrive on scene to a 58-year-old male patient describing pain in his chest. While your partner is starting a set of vitals, you follow up asking him to describe the chest pain and if it radiates anywhere. He describes the pain like “something squeezing his chest” and that he also feels pain in his jaw. He does not appear to be dyspneic or short of breath
While you are considering the next steps in your cardiac chest pain protocol, you are trying to remember if oxygen therapy would help this patient, considering he may have an acute myocardial infarction.
“In patients with suspected myocardial infarction, does oxygen therapy versus ambient air in a prehospital setting reduce patient mortality?”
|
Population |
Patients with suspected myocardial infarction |
|
Intervention |
Oxygen Therapy |
|
Comparison |
Ambient Air |
|
Outcome |
Reduction in mortality |
PubMed Search Terms: O2 therapy AND myocardial infarction AND mortality
("oxygen inhalation therapy"[MeSH Terms] OR ("oxygen"[All Fields] AND "inhalation"[All Fields] AND "therapy"[All Fields]) OR "oxygen inhalation therapy"[All Fields] OR ("o2"[All Fields] AND "therapy"[All Fields]) OR "o2 therapy"[All Fields]) AND ("myocardial infarction"[MeSH Terms] OR ("myocardial"[All Fields] AND "infarction"[All Fields]) OR "myocardial infarction"[All Fields]) AND ("mortality"[MeSH Terms] OR "mortality"[All Fields] OR "mortalities"[All Fields] OR "mortality"[MeSH Subheading])
132 Results (6 Relevant) on 2020-10-05
Historically, oxygen therapy has been administered to patients suspected of having an acute myocardial infarction (AMI) in both the pre-hospital and hospital settings. BCEHS handbook guidelines recommend oxygen therapy for patients who have symptomatic cardiac problems with dyspnea (BCEHS, ACS Medical Principals). Oxygen therapy is routinely used in patients with suspected AMI because oxygen therapy elevates blood oxygenation levels which is thought to improve oxygenation at the ischaemic myocardial site, and reduce myocardial tissue damage. This is suspected to reduce pain from ischemia, reduce infarct size, and reduce patient mortality. However, clinical evidence observing the beneficial or negative effects of oxygen therapy in AMI is limited.
A Cochrane systematic review (2015), combining data from four randomized controlled trials of patients (n=871) with confirmed AMI who received oxygen in a pre-hospital and hospital setting, found that there was no difference in mortality between patients who received oxygen therapy and patients who received room air (Cabello et al., 2016). Stub et al. (2015) published a randomized control trial (n=638) that suggested that normoxic STEMI patients who received oxygen therapy had an increased absolute myocardial infarct size, but they found when myocardial size was calculated as a percentage of the left ventricle there was no difference in infarct size. Khoshnood et al. (2018) found that normoxic STEMI patients (n=95) receiving oxygen therapy before a percutaneous coronary intervention (PCI) had no difference in myocardial salvage or infarct size compared to patients receiving room air. Hofmann et al. (2017), in a randomized control trial, found that normoxic patients (n=6629) receiving oxygen therapy with a suspected AMI had no difference in 1-year mortality compared to patients receiving room air. Finally, Sparv et al. (2018) found that in normoxic STEMI patients (n=622) undergoing PCI who received oxygen therapy had no difference in pain level compared to patients receiving room air. These studies observe that oxygen therapy may not have a conclusive effect on patient pain, infarct size, or mortality.
The American Heart Association’s (2015) most recent guidelines suggest that oxygen therapy in suspected acute coronary syndrome* (ACS) without hypoxia has not shown a reduction in mortality or improvement in the resolution of chest pain (O’Connor et al., 2015). Additionally, they recognize that the utility of oxygen therapy in patients with suspected ACS without hypoxia has not been proven and that in pre-hospital settings withholding oxygen therapy may be considered (O’Connor et al., 2015).
* To note, acute coronary syndrome is an umbrella term that encapsulates situations where blood flow is suddenly reduced to the heart. AMI is a type of acute coronary syndrome.
In normoxic patients (SpO2 ≥95%) who present with a suspected AMI with no signs of respiratory distress or shortness of breath, oxygen therapy given by paramedics may not have an effect on reducing mortality, morbidity, infarct size, or pain. Paramedics may consider withholding oxygen therapy based on their clinical judgement.
In patients who present with a suspected AMI and are in respiratory distress, have shortness of breath, or hypoxia, oxygen therapy is indicated and should not be withheld. Paramedics should aim to titrate oxygen therapy to an SpO2 value of 95% for these patients. Patients with COPD should have their SpO2 value titrated to around 92-95%.
For more detailed guidelines on oxygen therapy usage and SpO2 values in AMI please refer to “Oxygen Therapy” and “Acute Coronary Syndrome (ACS) – Medical Principles” in the BCEHS handbook.