Analysis of Oxygen Therapy in Myocardial Infarction: Case Studies

This case study examines the application of oxygen therapy in the treatment of acute myocardial infarction (AMI), also known as a heart attack. It begins with an introduction to AMI, its causes, and the rationale behind oxygen therapy. The study then delves into published evidence, including guidelines from various organizations like the American Heart Association and the Australian Clinical Guidelines, discussing the benefits and potential harms of oxygen supplementation. The core of the study involves two clinical vignettes: Mika's case, where shortness of breath was present, and Mr. Herz's case, where oxygen saturation was normal. The cases are analyzed in light of current guidelines, assessing the appropriateness of oxygen therapy based on the patient's symptoms and vital signs. The study concludes by weighing the risks and benefits of oxygen therapy, emphasizing the importance of careful administration and monitoring to avoid complications such as hyperoxia and pulmonary damage. The study uses references to support its findings and recommendations.

CLINICAL
VIGNETTE CONCEPT

TABLE OF CONTENTS
INTRODUCTION...........................................................................................................................1
Discussion on published evidence..............................................................................................1
Mika's case..................................................................................................................................2
Mr. Hers case..............................................................................................................................3
REFERENCES................................................................................................................................5

INTRODUCTION
Acute “myocardial infarction” is the medical term of heart attack. It generally occurs
during the blockage in flow of blood to the heart and causes severe damage to all the tissue and
in critical cases may lead to death. Many factors are responsible for increasing the chances of
heart attack like increasing blood pressure, diabetes and high cholesterol level in body.
In most of the cases patient suffering with acute myocardial infarction is given oxygen
therapy in form of emergency treatment. Supply of oxygen to the patient in this case is
considered to be the best therapy. Supplementation of oxygen is the standard treatment method
for patients having heart related disease but in some cases, it may be considered dangerous for
the health of patients. According to the survey among physicians around 50% believe that
oxygen supply decreases the chances of mortality, 25% believe that it aids in lowering the level
of pain and left 25% thought that it has no effect on the body.
Discussion on published evidence
According to Oxygen Guidelines for Acute Oxygen Use in Adults (2015), it is logical to
and biologically accepted to provide patient with oxygen therapy in case of AMI, this is done to
enhance the oxygenation of ischemic myocardial tissues and help in decreasing the pain related
to ischemia. But on the other side it can also proved to be harmful in decreasing the blood flow
of coronary artery and increases resistance of coronary vascular which was measured by using
intra coronary Doppler ultrasonography. Decrease in level of cardiac output and stroke volume,
hyperoxia leads to increase in the vascular resistance and injury due to re perfusion because of
the increasing number of free oxygen radicals. But in situation of lack in myocardial perfusion
their is decrease in level of oxygen in myocardium and in this case oxygen therapy is used to
increase the concentration of oxygen in blood vessels.
Non-random study performed by Nicholson proves that oxygen can increase the
myocardial ischemia. According to Australian Clinical Guidelines for the Management of Acute
Coronary Syndromes (2016), Air verses Oxygen In myocardial infraction study (AVOID)
mentioned that the regular supply of oxygen in case of acute myocardial infraction can prove to
be harmful for heart. According to this study there was increase in the creatine kinase that
increased the myocardial injury and cardiovascular magnetic resonance technology was used for
imaging that shows increase in the size of infraction after oxygen therapy.
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The recent guidelines given by Acute Coronary Syndromes (2016), STEMI addressed
that oxygen should be recommended to the hypoxic STEMI patients having atrial oxygen
saturation less than 90%. In contrast to this Guideline for the Management of Patients with Non-
ST-Elevation Acute Coronary Syndromes (2014), suggests that oxygen that is supplied should be
of saturation less than 90% for the patients with distress related to respiration. On the other hand,
American Heart Association Guidelines for CPR & ECC (2015), provided more specific
information regarding use of oxygen therapy. It suggests that with the results excessive high
atrial oxygen concentration causes harm to various organs. The guidelines also advise to
administer the patients routinely who are supplied oxygen, it can be monitored using pulse
oximetry. According to them supplement of oxygen should only be given to: people having
oxygen saturation >94% and not at risk of respiratory failure. And to the people with chronic
pulmonary disease who are at risk of hypercapnic respiratory failure.
It is always considered that oxygen therapy is mainly given to the patients in condition of
hypoxaemia but not in the case of breathlessness. But there is a risk that is associated with both
cases of hypoxaemia and hyperxaemia that prescribe that oxygen should be given in this case but
within the targeted oxygen saturated rate. Similarly, in case of person facing problem of
breathlessness use of high concentration of oxygen causes deterioration to the supporting tissues
and may further delay in initiating the further treatment. As it has been mentioned that according
to the current acute coronary syndrome (ACS) oxygen supply should only be provided in certain
conditions like: if patients are suffering from breathlessness, in case of hypoxaemia lower than
94% and if any sign of heart failure or shock prevails (Cherian and et.al., 2014).
Mika's case
In case of Mika, breathing rate was 20 breathe per minute and was facing mild shortness
of breath also the capillary refill time was normal. Circulation of blood seen to be well perfused
along with normal blood pressure with clear airways. After performing the cardiac
catheterisation, it was observed that there was 80% lesion in left main coronary artery which was
extending towards anterior descending artery. Due to this cardiopulmonary bypass surgery was
performed to remove the cardiac tumour. Since there is mild shortness of breath is present then
according to current acute coronary syndrome guidelines in case of breathlessness oxygen supply
should be given to the patient.
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As oxygen is supplied, it is necessary to keep a regular check on the amount of oxygen
provided to patients because excessive supply may lead to many heart related disease. In case
related to Mika, the airways are open so there is no need to use nebulizers we can directly go
with oxygen therapy. This therapy will provide Mika with adequate supply of oxygen and
prevent the risk of heart strokes (Ding and et.al., 2013). Along with this it will help in improving
the stamina and mental alertness in Mika. In case if Mika is not supplied with proper supply of
oxygen, then it will result in hypoxia and may also result in hypoxaemia which results in low
arterial oxygen tension. This comes in favour of providing Mika with short term oxygen therapy.
There is no need of supplying oxygen after meeting normal demand, it can be detected when
patient start feeling comfortable. Before cutting off with external supply various parameters
needed to be checked first including respiratory rate, heart rate, skin colour, blood pressure and
pulse oximetry.
Weaning of supply can be done either by discontinuing the supply at once or by lowering
the concentration of supply and finally stop it. Many risks are associated with the long-term
oxygen supply which includes physical and functional risk along with cytotoxic damages.
Physical risk is regarding the combustion process that can result in the explosion of tank. Other
risks are injury to nose and face from catheters and masks along with dryness from non-
humidified gas. Along with this oxygen therapy can causes structural and functions damages to
the lungs. In the test of autopsy both proliferative and fibrotic changes are seen in the lungs. So
proper administration is required while providing patients with oxygen therapy (Harch, 2013).
Mr. Herz case
In the case of Mr. Herz, during the vital test he was responsive to the environment and
was verbally answering the service providers. Breathing rate was high but not that much, along
with capillary refill time of 2 seconds which was quite normal. SpO2 rate was 99% and
according to the current acute coronary syndrome guidelines which states that supplemental
oxygen should not be provided to patients in case hypoxaemia rate higher than 94%
(SpO2<94%). So, there is no need of providing oxygen therapy to Mr. Herz as everything was
found to be normal while diagnosis. In such cases giving this therapy unnecessarily can result in
serious threats to organs an lungs. Increase in oxygen supply enhances the microvascular
resistance that will result in reduction in the flow of coronary blood. This process finally decline
the cardiac output and enhance the radical oxygen species that may further have its negative
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impacts and causes risk of getting affected by arrhythmias and damages to cells that causes heart
failure (Sunkari and et.al., 2015).
Excessive supply of oxygen may increase the hypoventilation in the patients, which
includes hypercapnia on carbon dioxide necrosis. Patients having problem in holding carbon
dioxide with decrease in pH may get adversely effected by the excessive supply of oxygen. The
exposure of body to high level of oxygen leads to parenchymal changes due to increase in the
pressure of oxygen in the blood vessels (Camporesi and Bosco, 2014). It causes
tracheobronchitis and pulmonary interstitial fibroses that arises with symptoms like nausea,
vomiting, feeling of burning in chest, cough problems and headache. In some cases, due to long
term exposure to oxygen therapy large volume of nitrogen which is present in lungs get replaced
by oxygen. This amount of oxygen is then absorbed into the blood that reduces volume of alveoli
which finally result in alveolar collapse resulting in phenomenon called absorption electasis. As
a result, it causes many symptoms like cough, chest pain, cyanosis, increase in the rate of heart
and causes difficulty in breathing process. So, it is necessary to prohibit the use of oxygen
therapy unnecessarily as a result instead of providing benefit to our body it may become the
cause of severe complications.
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REFERENCES
Books and journals
Camporesi, E. M. and Bosco, G., 2014. Mechanisms of action of hyperbaric oxygen
therapy. Undersea & hyperbaric medicine: journal of the Undersea and Hyperbaric
Medical Society, Inc. 41(3). pp.247-252.
Cherian, S. and et.al., 2014. Oxygen therapy in preterm infants. Paediatric respiratory
reviews. 15(2). pp.135-141.
Ding, Z. and et.al., 2013. Hyperbaric oxygen therapy in acute ischemic stroke: a
review. Interventional neurology. 2(4). pp.201-211.
Harch, P. G., 2013. Hyperbaric oxygen therapy for post-concussion syndrome: contradictory
conclusions from a study mischaracterized as sham-controlled. Journal of
neurotrauma. 30(23). pp.1995-1999.
Sunkari, V. G. and et.al., 2015. Hyperbaric oxygen therapy activates hypoxia‐inducible factor 1
(HIF‐1), which contributes to improved wound healing in diabetic mice. Wound Repair
and Regeneration. 23(1). pp.98-103.
Online
Acute Coronary Syndromes. 2016. [Online]. Available through
<https://www.nzrc.org.nz/assets/Guidelines/ACS/All-ACS-guidelines-Jan-2016.pdf>.
[Accessed on 1st September 2017]
Australian Clinical Guidelines for the Management of Acute Coronary Syndromes. 2016.
[Online]. Available through
<https://www.heartfoundation.org.au/images/uploads/publications/ACS-guidelines-long-
presentation_2016_v2_1.pdf>. [Accessed on 1st September 2017]
Oxygen guidelines for acute oxygen use in adults. 2015. [Online]. Available through
<https://www.thoracic.org.au/journal-publishing/command/download_file/id/34/
filename/TSANZ-AcuteOxygen-Guidelines-2016-web.pdf>. [Accessed on 1st September
2017]
Guideline for the Management of Patients With Non-ST-Elevation Acute Coronary Syndromes.
2014. [Online]. Available through
<http://circ.ahajournals.org/content/early/2014/09/22/CIR.0000000000000134>.
[Accessed on 1st September 2017]
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American Heart Association Guidelines for CPR & ECC. 2015. [Online]. Available through
<https://eccguidelines.heart.org/index.php/circulation/cpr-ecc-guidelines-2/>.
[Accessed on 1st September 2017]
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