A Reminder of an Important Clinical Lesson: Hypoxaemia in a Pleural Effusion

Round 1

Reviewer 1 Report

The author attempts to review mechanisms behind dypsnoea and hypoxaemia based on a single case study. This appears to be an insufficient basis for the review given that this case study may be a special case. I suggest that the author may attempt to collate similar cases before attempting a review that would have a great impact on this important medical condition.

Author Response

Thank you for this comment and I understand where you are coming from and what you are hinting at.

However, this is a case report, based on a single person for whom we got consent for publication. Attempting a case series would certainly give more validity to the question posed, but in this current report, is impossible to do, and would require further time for patient recruitment, and correction of confounding factors, which is beyond what we can achieve at the moment. I would also like to point out the studies we have referenced as they have studied similar cases, and their results are what is being alluded to in our case report. 

Thank you, Avinash Aujayeb

Reviewer 2 Report

The author documented a 75-year-old man had malignant pleural effusion and persistent hypoxemia after draining out effusion, and finally, a severe pulmonary embolism was disclosed. However, chest CT was arranged after drained out effusion is a common process to elucidate the etiology of effusion, it is not an uncommon process.

1. The author had to point out the location of pulmonary embolism in figure 1b, it is not clear.
2. Did the effusion analysis in the case include the ratio of neutrophil and mononuclear cells? The low ratio could indicate the possible cancers instead of infection.
3. Pulmonary embolism always comes from deep venous thrombosis, it is a common event in lung cancer patients. Did the patient have DVT and how about his D-Dimer value?

Author Response

Thank you for your comments, which I have considered carefully.  I apologise about figure 1b. A new version has now been uploaded, not in the main document, but a part of the zip file. 

The effusion was predominantly lymphocytic, which suggests a malignant cause and that has been added to the script. 

The point about DVT and PE is valid and the patient did indeed have bilateral leg USS which did not show any DVT. This has been added to the text. 

The D dimer of the patient was 4 milligrams/litre fibrinogen-equivalent units (mg/L FEU) {Local reference range: age-related cut-off for patients > 50 years old: normal range is < Age divided by 100mg/L FEU}. This has also been added to the text. 

Reviewer 3 Report

The manuscript entitled “A reminder of an important clinical lesson: hypoxaemia in a pleural effusion” depicts the case report of hypoxaemia in a pleural effusion case.

The manuscript is well written and easy to understand. The references used in the manuscript are recent and are adequate.  Regarding the novelty of the manuscript as far as I am concerned there are few reviews covering this topic.

In my opinion, the results shown in this case report are interesting for a broader community and deserve to be published, nonetheless. Despite its great potential, the paper comes with a few issues which are addressed below:

• The author should follow the journal instructions on the reference section:

1. Author 1, A.B.; Author 2, C.D. Title of the article. Abbreviated Journal Name Year, Volume, page range.

• In the introduction, … such as Ig4 disease or rheumatoid arthritis. Should it be igG4 disease instead of Ig4?
• When expressing thousands in number, sometimes thousand comma separator is used, while others is not used, please, consistency.
• In the Case Report section change PaCo2 with PaCO2. Ph for pH.
• Sometimes units are used with symbols and others with full name, use the same criteria in the text to make it clearer
• When using et al. add the final point.
• Provide Figure 1 caption.

Best regards

Author Response

I thank the reviewer for his/her comments, and I have sorted the references out. 

I have corrected the reference to IgG4 disease. I have added commas in the thousands used. 

I have changed change PaCo2 with PaCO2 and Ph for pH.

All the units are now spelled out in full. 

I have added the . after et al., and the figures have been sorted as required

Many thanks, Avinash Aujayeb 

Round 2

Reviewer 1 Report

i consider the author's response to my suggestions to be fair and i accept the manuscript in its current format.

Author Response

Thank you for your comments. No further changes are required to the manuscript

Reviewer 2 Report

After revision, the current manuscript is acceptable 

Author Response

Thank you for your comments. No further changes are required to the manuscript.