John Barker
49, Male
Click on the tabs below to view the results and interpretation of these investigations.
Consider the questions for each section, asking you to interpret these investigations; click on the question panels to reveal model answers.
Full blood count
Explanation:
Occasionally cardiac chest pain can be triggered by severe anaemia. In addition, if the patient is anaemic it may suggest occult bleeding which would require further investigation and questioning. Although the full blood count result will not be back prior to mechanical reperfusion (balloon and stent), the presence of a low haemoglobin will heighten awareness to look out for further bleeding and limit the use of further anticoagulants such as heparin and powerful antiplatelet drugs.
Results
| Investigation Name | Investigation Result | Normal Range | Units |
|---|---|---|---|
| Haemoglobin | 160 | 115-165 | g/L |
| White cell count | 10.1 | 4-11 | x109/L |
| Neutrophils | 6.8 | 1.5-7.0 | x109/L |
| Platelets | 350 | 150-400 | x109/L |
Questions: Click on the question panel below to see the model answer...
Question: Interpret the result
Model answer:
The results are normal. Any acute inflammatory event can cause an increase in the neutrophil count.
Electrolytes, urea, creatinine
Explanation:
Coronary artery disease may be accompanied by renal artery disease and abnormal renal function. Although this does not alter immediate management, it suggests caution is required regarding the use of secondary prevention drugs such as ACE inhibitors.
Results
| Investigation Name | Investigation Result | Normal Range | Units |
|---|---|---|---|
| Sodium | 141 | 137 - 145 | mmol/L |
| Potassium | 4.2 | 3.5 - 4.9 | mmol/L |
| Urea | 4.5 | 2.5 - 7.5 | mmol/L |
| Creatinine | 97 | 60 - 110 | µmol/L |
Questions: Click on the question panel below to see the model answer...
Question: Interpret the result:
Model answer:
The results are normal
Blood glucose
Explanation:
This is often abnormal in acute myocardial infarction. If it is raised, it may indicate previous diabetes in which case the glycosylated-haemoglobin will also be abnormal (reflecting glucose levels over the last two months) Alternatively it can be raised as part of the “stress response”.
Results
| Investigation Name | Investigation Result | Normal Range | Units |
|---|---|---|---|
| Glucose | 14 | Random < 11 | mmol/L |
| Glycosylated Haemoglobin | 5.2 | < 6 | % |
Questions: Click on the question panel below to see the model answer...
Question: Interpret the result:
Model answer:
The glucose concentration is elevated; this is typical of a stress response, with catecholamine release leading to glycogenolysis. The normal HbA1c suggests that the patient does not have diabetes.
Cholesterol
Explanation:
If this is taken within the first few hours of symptoms, it is likely to reflect the cholesterol before coronary artery occlusion. In addition, it is worth measuring low density lipoprotein (LDL) and high density lipoprotein (HDL).
Results
| Investigation Name | Investigation Result | Normal Range | Units |
|---|---|---|---|
| Total Cholesterol | 9.8 | < 5 | mmol/L |
Questions: Click on the question panel below to see the model answer...
Question: Interpret the result:
Model answer:
This is elevated into the range typical of familial hypercholesterolaemia. Note that since there is a continuous association between cardiovascular risk and total and LDL cholesterol concentrations, extending to total cholesterol concentrations even below 5mmol/L, it is inappropriate to use the term ‘normal’ value. It is more relevant to consider ‘ideal’ values or targets for treatment.
Arterial blood gases
Explanation:
The patient is breathless and there are signs of pulmonary oedema. Arterial blood gases will document whether oxygenation is impaired. This is particularly important if pulse oximetry suggest that saturation is lower than 93%. In addition, the low blood pressure and tachycardia suggest organ perfusion is compromised and this can be documented by measuring the base excess.
Results
| Investigation Name | Investigation Result | Normal Range | Units |
|---|---|---|---|
| PaO2 (breathing air) | 7.2 | 11.0 - 13.5 | kPa |
| PaCO2 | 3.8 | 4.8 - 5.6 | kPa |
| pH | 7.47 | 7.35 - 7.45 | |
| [H+] | 34 | 35 - 45 | nmol/L |
Questions: Click on the question panel below to see the model answer...
Question: Interpret the result:
Model answer:
John is hypoxaemic; a PaO2 less than 8 kPa indicates respiratory failure. The slightly low [H+]/high pH indicates a mild alkalosis. The low PaCO2 indicates the alkalosis is respiratory in origin (hyperventilation, he is “blowing off” his CO2 in excess of the CO2 being produced by metabolism, leading to a reduction of the partial pressure of CO2 in arterial blood). Impaired gas exchange as a consequence of pulmonary oedema and ventilation/perfusion mismatch is the likely cause.
Echocardiogram
Explanation:
This measures the anatomical structures of the heart and how they move in the cardiac cycle. It can be used to measure the fraction of blood ejected during systole, the presence of a wall motion abnormality in the region of myocardial infarction and document complications of myocardial infarction such as mitral regurgitation- secondary to papillary muscle dysfunction/rupture or a ventricular septal defect. It is increasing used in the acute setting (FAST or FEEL scan) to increase the certainty of MI diagnosis and estimate the amount of potential damage to the heart.
Results
Ejection fraction 40% large dyskinetic segment affecting the inferior/posterior segments of the left ventricle.
(Normal ejection fraction is greater than 55%)
Questions: Click on the question panel below to see the model answer...
Question: Interpret the result
Model answer:
Compatible with reduced left ventricular ejection fraction as a consequence of acute myocardial ischaemia in RCA territory