Oxygen Therapy in Acute Myocardial Infarction Alexandra Tatis and Abigail Campbell University of New Hampshire

Transcription

1 Running Head: OXYGEN THERAPY IN ACUTE MYOCARDIAL INFARCTION 1 Oxygen Therapy in Acute Myocardial Infarction Alexandra Tatis and Abigail Campbell University of New Hampshire

2 OXYGEN THERAPY IN ACUTE MYOCARDIAL INFARCTION 2 Introduction The administration of oxygen therapy during an acute myocardial infarction has been part of the recommended first line treatment to prevent further damage of the heart muscle. Currently, oxygen therapy is believed to reduce the workload of the heart often accompanied by a heart attack. However, recent clinical evidence, which will be explained further throughout the paper, shows that this treatment could cause adverse effects in the patients. These adverse effects include an increase in myocardial infarction size, recurrent myocardial infarctions and even possible mortality. Results from the studies researched varied tremendously. Some studies provide evidence against oxygen administration while others demonstrate that oxygen can be helpful. Evidence serves as a foundation for the nursing practice. Nursing interventions should be evidenced based in order to provide safe and optimal care for patients. The role of a nurse requires lifelong education and knowledge building due to evolving practices based on new and improved research studies. A nurse must understand the rationale behind interventions that he or she is taught to perform. In the care for patients with an acute myocardial infarction, nurses are taught that the interventions for an acute myocardial infarction include: oxygen, morphine, nitroglycerin, aspirin and beta-blockers. The responsibility of the nurse is to understand the significance of these interventions in order to critically think and provide adequate nursing care. The recent evidence that suggests oxygen is a potentially harmful intervention in an acute myocardial infarction is important to nursing care. New or improved evidence influences changes in practice for nurses.

3 OXYGEN THERAPY IN ACUTE MYOCARDIAL INFARCTION 3 Search Methods The search engine that was used to research this topic was EBSCO Host. Under this search engine, the databases used were Academic Search Complete, Cumulative Index to Nursing and Allied Health Literature and Health Source: Nursing/Academic Edition. Key words included oxygen therapy, myocardial infarction, tissue damage and hospital. The data bases allowed a main topic with an "and" section to further narrow the topics and group the terms in different ways. In order to further narrow these results down to the most useful articles and journals, the limits set were full text, peer reviewed and English only. After reviewing all of the results that showed up, there were five articles that most accurately studied the topic of oxygen therapy versus no oxygen therapy in a myocardial infarction. Patients with a STEMI were included in the data collection while patients who were experiencing a non-stemi were excluded. Critical Appraisal of the Evidence The first study examined, Air Versus Oxygen in ST-Segment Elevation Myocardial Infarction, addresses the question of whether or not oxygen had an impact on size and reoccurrence of myocardial infarctions (MI). This was a level two evidence study that involved a multicenter, prospective, randomized, controlled trial with 638 patients. These patients were admitted to the emergency room within nine hospitals. Two groups were formed; one receiving eight liters/min of oxygen while the other group remained on room air during an acute MI. Patient criteria included being over 18 years old, having chest pain that had begun within the past 12 hours and a pulse ox of 94% and over. Out of the 638 randomized patients, 441 patients were confirmed to have ST elevation (Stub, 2015 p. 2144).

4 OXYGEN THERAPY IN ACUTE MYOCARDIAL INFARCTION 4 The patients that were found to have ST elevation after a myocardial infarction were evaluated twice. During the first evaluation directly following the MI, lab values were interpreted to assess the size of infarct. These lab values included troponin I, creatine kinase and cardiac enzymes (Stub, 2015 p. 2147). In the six months following the MI, infarct size was assessed using cardiac magnetic resonance imagining, commonly known as an MRI. While there was no significant difference in troponin I between the oxygen and room air groups, there was significant evidence of elevated creatine kinase within the group receiving oxygen. In addition, the myocardial infarction reoccurred in the oxygen group more often than in the non-oxygen group. The results that were found through the MRI in the following six months revealed a larger infarct size in the oxygen group. Overall, the results concluded that the use of supplemental oxygen in patients with an MI and without hypoxia led to a larger MI size and subsequent MIs. This article presents with multiple strengths and only one weakness. Strengths included a large sample size and a relatively high level of evidence as a level two study. These factors indicate that the results from the study are presumably accurate. The weakness identified was that the study did not specify the number of people in the oxygen versus room air groups. Knowing the sample size of these individual groups would help to clarify the credibility and clinical significance of the results. In the second article, Oxygen in the Setting of Acute Myocardial Infarction: Is It Really a Breath of Fresh Air?, a level one systematic review with a meta analysis was used in order to determine the effectiveness of titrated oxygen in an acute MI. Out of 4,371 studies that were identified during the systemic review, 162 of them were reviewed and only five were included in the final analysis. Of the studies reviewed, a total of 446 patients were put on oxygen and 467

5 OXYGEN THERAPY IN ACUTE MYOCARDIAL INFARCTION 5 were on room air. The study examined the mortality rates, size of the infarction and the mass using MRI technology post myocardial infarction. This analysis found no significant difference between giving titrated oxygen versus room air to patients with an acute MI in comparing in-hospital mortality, infarction percentage and infarction mass. In the group receiving high concentration oxygen, the mortality rate was only 4% (Loomba, 2016, p. 146). In comparison, the patients on room air had a morality rate of 3% (Loomba, 2016, p. 145). These results do not reveal a significant difference. The researchers conducted an additional randomized controlled study in order to narrow the scope of the research. They studied 286 patients on titrated oxygen and 291 patients on room air. The results of this additional study showed no clinical significance that titrated oxygen had an impact on the mass size and percentage following an acute MI. This study presented with several strengths. A large sample size of 913 patients allows the researchers to generalize their findings to the population and conclude that the results found were not due to chance. Another strength considered is the level of evidence. Studies that use systemic reviews and meta-analyses are considered very reliable as they are categorized as a level one study. The experts of the study also identified several weaknesses. One limitation was that troponin and BNP levels were not available to compare to the MRI results (Loomba, 2016, p. 148). Additionally, the literature reviewed by the experts does not specify whether or not the patients received oxygen prior to arriving at the hospital (Loomba, 2016, p. 148). For instance, oxygen is often received during the ambulance ride to the emergency department. The third article, Systemic Review of the Effectiveness of Oxygen in Reducing Acute Myocardial Ischemia, is a systemic review that included nine trials. Two of these studies were randomized controlled trials while the other seven were non-randomized clinical trials (Nicholas,

6 OXYGEN THERAPY IN ACUTE MYOCARDIAL INFARCTION , p. 998). The studies examined all subsections of acute coronary syndrome including acute myocardial infarctions, ischemia and unstable angina. Six of the nine trials focused on myocardial infarction. The researchers used a variety of databases such as DARE, MEDLINE and CINAHL and included a broad selection of patient demographics. There were no exclusions of gender, race or age across the literature that was reviewed. The trials selected for this study were not specific to any timeframe. Additionally, the systemic review states, "No exclusions were made based on the flow rates of oxygen or delivery devices used by studies (nasal cannula, masks and tents)" (Nicholas, 2004, p. 1000). This systemic review represents a broad scope of evidence used for analysis. The nine trials were thoroughly reviewed and examined for the effectiveness of oxygen therapy for acute coronary syndrome. The evidence found for acute myocardial infarctions was assessed through quantitative data analysis. The four outcomes used to measure the data were metabolic markers, electrocardiograms, changes in patient symptoms, and hemodynamic parameters (measure changes in blood flow as an indicator of oxygen delivery) (Nicholas, 2004, p. 1004). This data was analyzed into graphs and tables to display the effects of oxygen therapy on these patients. According to the systemic review conducted, oxygen therapy either reduced the size of the infarction or increased the size of the infarction on patients. Overall, there is no definite conclusion of the effectiveness of oxygen therapy during an MI. The evidence surrounding this topic based on this article is quite unclear. Many limitations were found throughout the study. One limitation that should be considered is the failure to include the graphs and tables discussed in the article. Lack of visualization and specific numbers to correlate with their evidence creates a gap in the presentation of the research. In order to gain more factual research, the study suggested that an

7 OXYGEN THERAPY IN ACUTE MYOCARDIAL INFARCTION 7 experimental-design clinical research study would be needed (Nicholas, 2004, p. 1006). Therefore, the results cannot be considered credible if further research is needed. Another weakness includes the lack of current evidence throughout the article. The article itself is from 2004 while the research they examined dated back to the 1990 s. The only strength of this study was the wide range of participants. Evidence Synthesis The evidence regarding the use of oxygen during an acute myocardial infarction is collectively unclear. The most recent articles from 2015 and 2016, Air versus Oxygen In ST- Segment Elevation Myocardial Infarction and Oxygen in the Setting of Acute Myocardial Infarction: Is it Really a breath of Fresh Air, concluded opposing evidence. In the study, Air versus Oxygen In ST-Segment Elevation Myocardial Infarction, oxygen therapy was found to increase infarct size in patients who were normoxic but still received the oxygen during their MI. Although the second article, Oxygen in the Setting of Acute Myocardial Infarction: Is it Really a breath of Fresh Air, revealed no significant difference between oxygen versus room air, the oxygen saturation of the patients studied was not specified. It is important for research purposes to know the patient s pulse ox level prior to administration of oxygen because this can play a role in the size of the infarct. The second article was not inclusive to normoxic patients, therefore, the results cannot be equally compared. The third article, Systemic Review of the Effectiveness of Oxygen in Reducing Acute Myocardial Ischemia, shows no clear evidence based off a thorough systemic review. However, this article included outdated studies which suggests the results may not be up to pace with new and evolving research. Each article represents a high level of evidence, either level one or level two. The results shown are credible and reliable although they all present with weaknesses and have inconsistent conclusions.

8 OXYGEN THERAPY IN ACUTE MYOCARDIAL INFARCTION 8 Clinical and Research Recommendations In light of the conflicting evidence results from the articles examined, it is clear that more extensive research regarding the use of oxygen therapy during an acute MI needs to be done. Currently, the clinical practice guidelines still recommend oxygen as treatment for a myocardial infarction. In practice, oxygen therapy will still be used during an acute MI unless further research proves otherwise. The evidence opposing the guideline is not clinically significant enough to create a change in practice. Inconsistent evidence of the articles studied suggest the need for further trials.

9 OXYGEN THERAPY IN ACUTE MYOCARDIAL INFARCTION 9 References Loomba, R. S., Nijhawan, K., Aggarwal, S., & Arora, R. R. (2016). Oxygen in the Setting of Acute Myocardial Infarction: Is It Really a Breath of Fresh Air?. Journal Of Cardiovascular Pharmacology & Therapeutics, 21(2), Nicholson, C. (2004). A systematic review of the effectiveness of oxygen in reducing acute myocardial ischaemia. Journal Of Clinical Nursing, 13(8), Stub, D., Smith, K., Bernard, S., Nehme, Z., Stephenson, M., Bray, J. E., &... Kaye, D. M. (2015). Air Versus Oxygen in ST-Segment-Elevation Myocardial Infarction. Circulation, 131 (24),