Investigative Procedures Case Discussion
Name: Miss M.S.
Age: 23
Date of Birth:
Nationality: Australian
Sex: Female
Case Summary
Presenting Complaint
Miss M.S. is a 23 year old female with a 10 year history of Lupus with associated antiphospholipid antibody syndrome. She presented with SOB and a sharp pain in her back that was more painful on deep inspiration, which had come on the night before, after travelled up by plane from London.
She also complained of a hot, painful rash on her stomach that had also appeared the previous night.
Past medical history
-2000 DVT
-2002 Pneumonia
-2002 Anaemia
-2002 Nerve Pain
-Kidneys affected by Lupus –known proteinuria + small infarcts
Drug History
Aspirin 100mg OD
Prednisolone 10mg OD
Azathioprine 25mg OD
Plaquenil (Hydroxychloroquine) 200mg OD
Nil else of note from history
Examination
The patient was alert, but was tachypnoeic (25bpm) and tachycardic (96bpm).
Her oxygen saturation was 99% on 4 litres. There were no murmurs and her lungs were clear with good air entry bilaterally.
There was a butterfly rash on her face and an erythematosus, vesicular rash over her abdomen, which did not cross the midline and was in a T8 dermatonal distribution.
Initial blood gases on air showed Miss M.S. to be hypoxic with a PO2 of 9.08

Case Discussion
The history and examination findings meant that were two probable causes for Miss S.M.’s shortness of breath and back pain, pulmonary embolus or
Herpes Zoster infect ion. The rash on Miss M.S.’s abdomen was a classical
Herpes Zoster rash and therefore made this the most likely diagnosis, since it would be unusual (and unfortunate) to have a pulmonary embolis AND shingles occur at the same time. However, shingles would be unlikely to cause Miss S.M.’s hypoxia and, given her antiphospholipid syndrome, made pulmonary embolus a potential diagnosis.
This essay will briefly discuss what antiphospholipid antibody syndrome is and how Miss S.M. was investigated to confirm the diagnosis of shingles and exclude pulmonary embolism.
Antiphospholipid antibody syndrome is linked with systemic lupus erythematosus 1 . The syndrome causes inhibition of phospholipid-dependant coagulation factors and leads to a hypercoagulable state 2 . This means that people with the syndrome are much more likely to suffer
DVT’s, stroke and, in women, a higher risk of abortion 2 .
Pulmonary Embolism is a differential diagnosis in any person who presents with a sudden shortness of breath and pleuritic chest pain. Miss S.M.’s medical history made the chance of her having a pulmonary embolism (P.E.) even more likely and it therefore had to be excluded.
Where patients are suspected of having a P.E., it is important to look for signs of a DVT that could be the source of the embolism and ask the patient about recent surgery or immobility. Miss S.M. had not recently had any surgery, nor had any prolonged periods of immobility and reported no pain or discomfort in her legs. There were also no signs of a DVT on examination, such as swelling, heat or erythema.
The initial investigations for P.E. are oxygen saturations, an ABG, ECG, CXR and FBC, U+E’s + D-Dimers 3 . In P.E. you would expect the patient to be slightly hypoxic and this was indeed the case for Miss S.M..
The ECG is mainly useful to help exclude cardiac causes of chest pain and shortness of breath, but can also show signs of a P.E.. As a P.E. causes disruption to the blood flow to the lungs, this can cause a back pressure on the heart, leading to some ECG changes. The classical ECG changes in P.E. are S waves in lead 1 and Q waves and inverted T waves in lead 3 (S
1
Q
3
T
3
), however this is a rare sign and it is more common to see a sinus tachycardia,
AF and RBBB 3 . In Miss S.M.’s case there was only a slight tachycardia evident on the ECG.
A chest x-ray was ordered for Miss S.M., not only to look for signs of a P.E., but also to rule out other causes of shortness of breath, such as a pneumonia or pleurisy which also could be due to her SLE. Miss S.M.
’s CXR was clear and showed no signs of infection or signs of P.E., such as, pulmonary oligaemia, elevated hemidiaphram or pleural effusions 3 .

The FBC and U+E’s were checked to make sure that there were no other problems with Miss S.M.. The white cell count can be raised in P.E., but in
Miss S.M.’s case all blood results were normal.
The D-dimers were also checked as these are usually raised if a large clot has formed in the body. Although checking D-dimers is not particularly sensitive test, it can definitely exclude P.E. if it is undetectable 2 . In Miss
S.M.’s case her D-dimers were 0.44 and therefore did not help with her management.
At the same time all these initial investigations were done, a skin swab over the rash was also taken and sent to virology. In hindsight, this test was not necessary as the vesicular, erythematosus rash in a dermatonal distribution was classically shingles and did not affect the management of the patient as
Miss S.M. was started on Acyclovir on the day of admittance.
In order to definitively rule out the possibility of a P.E. Miss S.M. was sent for a V/Q scan or radionucleotide ventilation perfusion scan. In this investigation the patient placed in a scanner that detects radiation and is then injected with radioactive dye to show the perfusion of the lungs. This is then crossed referenced with the ventilation of lungs which is measured by the patient breathing in a radioactive gas. If the patient has had a P.E. then there will be an area of the lungs that is not perfused by blood but is ventilated. If the patient has not had a P.E. then the ventilation and perfusion scans should match.
A few days after having the V/Q scan, the report came back to say that there was;
“Normal ventilation and perfusion images obtained from both lungs.
There is no evidence of acute PTE”
Based on this result and the fact that Miss S.M.’s symptoms had improved, she was discharged from hospital.
It now seems apparent that all of Miss S.M.’s symptoms were caused by the
Herpes Zoster infection. The discomfort caused by the infection meant that it made breathing painful for Miss S.M., so causing her to hypoinflate her lungs.
This hypoinflation probably caused her shortness of breath and hypoxia.
This case illustrates how different investigations can be used to help exclude different diagnoses. While most of the investigations could not give a definitive diagnosis they were able to exclude other pathologies and guide the management of the patient. The V/Q scan was able to give definitive confirmation that Miss S.M. had not had a P.E. and allowed her to be discharged from hospital as soon as the results were known. Without such investigations it is possible that Miss S.M. could have been given potentially harmful anticoagulant medication and not allowed home so soon.

References
1. Longmore, M., Wilkinson, I. & Torok, E.Oxford. Handbook of Clinical
Medicine. 5 th Edition. Oxford University Press 2001.
2. Kumar, P. & Clark, M. Clinical Medicine. 4 th Edition. Harcourt Publishers
Limited 2001
3. Wyatt, J.P., Illingworth, R.N., Clancy, M.J., Munro, P. & Robertson, C.E.
Oxford Handbook of Accident & Emergency Medicine. Oxford University
Press 2001.