Pleural Effusion following Yoga: A Report of Delayed Spontaneous Chylothorax and a Brief Review of Unusual Cases in the Literature

Round 1

Reviewer 1 Report

Dear Editor and Authors,

I was very kindly asked to review the case report titled “Pleural effusion following yoga: A report of delayed spontaneous chylothorax and a brief review of unusual cases in the literature.” by Gabriel Hunduma and his colleagues.

In this report the authors describe a case of a 40 year old female patient which developed a spontaneous chylothorax and was managed by thoracic surgery!

I have the following comments to make:

1.       Please check the authors affiliations, “Division” is spelled wrong!

2.       In the abstract why do the authors, who are thoracic surgeons, omit to mention the itatrogenic causes of chylothorax which includes thoracic surgery and interventions. They have addressed / presented this in their introduction!

3.       What do the authors mean when they say “direct impact”; how could trauma, which I presume this is what they mean, cause “direct” and not transmitted impact and injuries?

4.       In the operations mentioned why do the authors omit to mention lung resections such as lobectomies/pneumonectomies and associated mediastinal lymph node clearance as a possible iatrogenic cause?

5.       How can a chylothorax be life threatening? The authors need to explain and elaborate on this? What is the mortality rate from chylothorax?

6.       What where the patient’s vital signs at presentation? Was she stable? What where her respiratory parameters?

7.       How many times did the patient attend the yoga class? How can we suppose this was the causation of the chylothorax?

8.       Why was the initial pleural effusion not investigated with a CT scan? Is it standard practice for undiagnosed pleural effusions in healthy patients to not be routinely investigated and followed up?? The authors need to address this and elaborate because the way it is now worded creates an unfavorable image!! Don’t forget the patient was readmitted a few hours later almost to the point of arrest!!

9.       How could the barium swallow rule out mediastinitis? This is not the examination of choice!! Do you mean it demonstrated no esophageal perforation and thus contamination of the mediastinal structures?

10.    How many ports was used for the VATS? Standard 3 port approach/uniportal? Please mention!

11.   What do you mean mass control? Do you mean you ligated the thoracic duct and the azygous?

12.   What is the point of mentioning lymph glands? You mean no evidence of malignancy and local duct infiltration were found!!

13.   Was a decortication performed to the lung or was it just evacuation of the pleural effusion?

14.    Did the lung have full expansion post-operatively?

15.   In the discussion it is not just mediastinal lymph node sampling that can cause thoracic duct injury! Lymph node dissection and clearance has  higher incidence of injury to the thoracic duct. Please address this in the discussion section!!

16.   I am uncertain the authors can make the correlation of their thoracic duct injury to the light exercise the patient did!! It is a bit of a stretch as a hypothesis considering the yoga class was 2 weeks prior and the patient deteriorated (and was readmitted to hospital) rapidly and within hours!! It is more likely given the presentation for someone to suppose this was a spontaneous chylothorax caused over a maximum of 24 hours!!!

17.   In the cases the authors present in their review what was the average time period the other authors have reported in the literature from hyperextension/stretching to chylothorax formation!!

In conclusion, this is not really an unremarkable and rare clinical case if one is to consider that spontaneous chylothorax can happen!! The authors are attempting to make this case more interesting and unique by presenting a tenuous at best association with hyperextention of the spine and the neck during exercise/yoga!! I am uncertain this is accurate and that the claim can be made. Therefore, I am reluctant to recommend the publication of the case unless this has been removed or toned down and not given such focus!!   

Needs some minor editing!

Author Response

We thank the reviewer for his favorable comments and helpful suggestions for improving the manuscript.

1. Q: Please check the authors affiliations, “Division” is spelled wrong!

R: Thank you for the review. Please find the changes applied.

2. Q: In the abstract why do the authors, who are thoracic surgeons, omit to mention the itatrogenic causes of chylothorax which includes thoracic surgery and interventions. They have addressed / presented this in their introduction!

R: Thank you for the review. We have added iatrogenic causes, in the abstract.

3. Q: What do the authors mean when they say “direct impact”; how could trauma, which I presume this is what they mean, cause “direct” and not transmitted impact and injuries?

R: Thank you for valuable comment. We have described indirect trauma from transmission of forces and direct trauma more clearly as seen in lines 25-26. “Injury of the duct can be caused by indirect trauma as a result of transmission of external forces but, more often, it results from  iatrogenic during surgeries, and this contributes to almost 50% of the cases”

4. Q: In the operations mentioned why do the authors omit to mention lung resections such as lobectomies/pneumonectomies and associated mediastinal lymph node clearance as a possible iatrogenic cause?

R: Thank you for your comment. Please find the addition of lobectomies/pneumonectomies on line 28. “Esophageal, aortic mediastinal, neck, and thoracic operations such as lobectomies or pneumonectomy are most commonly associated with chyle leak [2].”

5. Q: How can a chylothorax be life threatening? The authors need to explain and elaborate on this? What is the mortality rate from chylothorax?

R: Thank you for the review. Please find our further elaboration of morbidity and removal of the statement on mortality on lines 49-51. “ Chylothorax is associated with significant morbidity, is potentially lethal, and can result in respiratory, immunologic, respiratory, and nutritional impairment predominantly due to poor fat absorption [7]”

6. Q: What where the patient’s vital signs at presentation? Was she stable? What where her respiratory parameters?

R: Thank you for your comment. Please find addition of relevant observation details on lines 63-65. “Her blood pressure and heart rate were within normal range, however she did not require additional oxygen support to maintain saturations above 92% and respiration rate was at 14 breaths per minute.” We do not normally assess respiratory function in the emergency department if patients are not asthmatic.

7. Q: How many times did the patient attend the yoga class? How can we suppose this was the causation of the chylothorax?

R: Thank you for your comment. The patient attended the yoga class for the first time (see line 62). She performed a yoga posture involving very excessive hyperextension. She also reported practicing the movement at home the day before presentation to ED. She did not experience any trauma outside of that yoga session.

8. Q: Why was the initial pleural effusion not investigated with a CT scan? Is it standard practice for undiagnosed pleural effusions in healthy patients to not be routinely investigated and followed up?? The authors need to address this and elaborate because the way it is now worded creates an unfavorable image!! Don’t forget the patient was readmitted a few hours later almost to the point of arrest!!

R: Thank you for your valuable comment. As the patient was clinically stable and the effusion minimal, there was no indication to investigate further as this is not the usual practise in our emergency department. The effusion would have been more extensively investigated with CT imaging if the patient was clinically unwell. Please find changes in lines 66-68. “A chest x-ray showed minimal right pleural effusion which was conservatively managed and she was discharged home with analgesia as she was clinically well”

9. Q: How could the barium swallow rule out mediastinitis? This is not the examination of choice!! Do you mean it demonstrated no esophageal perforation and thus contamination of the mediastinal structures?

R: Thank you for your comment. This sentence was corrected on lines 98-99. “The barium swallow scan however did not show any extravasation of contrast ruling out esophageal perforation”

10. Q: How many ports was used for the VATS? Standard 3 port approach/uniportal? Please mention!

R: Thank you for your comment. Please find changes in lines 128-129. “surgical exploration was scheduled and a 2 port right video-assisted thoracoscopic surgery (VATS) was performed”

11. Q: What do you mean mass control? Do you mean you ligated the thoracic duct and the azygous?

R: Thank you for your valuable comment. Please find changes in lines 144-145. “We decided to perform mass control of the thoracic duct together with the azygos vein by ligating both vessels and performing total pleurectomy to achieve pleurodesis.”

12. Q: What is the point of mentioning lymph glands? You mean no evidence of malignancy and local duct infiltration were found!!

R: Thank you for the comment. Please find the changes in lines 143. Lymph glands was deleted as it was found redundant in the sentence. “No damage to thoracic duct nor obvious leak were found”

13. Q: Was a decortication performed to the lung or was it just evacuation of the pleural effusion?

R: Thank you for the comment. A parietal pleurectomy was performed.

14. Q: Did the lung have full expansion post-operatively?

R: Thank you for the review. Please find the change in Line 1415-146. “A satisfactory lung expansion was observed prior to skin closure.”  

15. Q: In the discussion it is not just mediastinal lymph node sampling that can cause thoracic duct injury! Lymph node dissection and clearance hashigher incidence of injury to the thoracic duct. Please address this in the discussion section!!

R: Thank you for your valuable comment. Please find the change in line 159-161. “Surgeries that involve posterior or superior mediastinum such as a foregut or aortic surgery or mediastinal lymph nodes sampling and limph nodes dissection are also common causes” 

16. Q: I am uncertain the authors can make the correlation of their thoracic duct injury to the light exercise the patient did!! It is a bit of a stretch as a hypothesis considering the yoga class was 2 weeks prior and the patient deteriorated (and was readmitted to hospital) rapidly and within hours!! It is more likely given the presentation for someone to suppose this was a spontaneous chylothorax caused over a maximum of 24 hours!!!

R: Thank you for your review. We will also address review number 17 here as well. Our paper is indeed presenting a topic that is a rare occurrence. We have found the timing of recently starting yoga and performing the movement the day before (within 24 hours) as too much of a coincidence, and more likely to hold an element of correlation although which will also be difficult to prove due to lacking prevalence. A literature review of such prevalence was therefore performed to identify historical events in chylothorax presentations without iatrogenic or other traumatic causes.

17. Q: In the cases the authors present in their review what was the average time period the other authors have reported in the literature from hyperextension/stretching to chylothorax formation!!

R: Thank you for your valuable comment. We added a comment in the Conclusion paragraph in order to enrich the message to our case report. See lines 313-319. “Our case was quite unique in that it occurred after a prolonged time (2 weeks) following modest exercise after a neck extension only, during introductory beginner yoga techniques. Other cases of spontaneous chylothorax after exercise have been described, but more likely to be attributable to sudden, stressful movements than those predicted by yoga relaxation techniques. As defined by experiences reported in the literature, surgical management aided by conservative therapy was also successful in our case.

Reviewer 2 Report

Congratulations to you on your successful treatment of this rare and possible fatal case. The entire manuscript was well written. The following are my comments.

(1) In your text, 'observation were unremarkable'. What does it mean ?

(2) When the patient was found to have right pleural effusion, how could you let her go home with only prescribing analgesic ? For me I would arrange further examination because it was very unusual.

(3) Did you let the patient drink some oil before the surgery ?

Author Response

We thank the reviewer for his favorable comments and helpful suggestions for improving the manuscript.

1) Q: In your text, 'observation were unremarkable'. What does it mean ?

R: Thank you for your comment. We reviewed the case presentation to avoid possible misunderstandings. The observation regarding the hypothesis of an emergent clinical scenario was considered unremarkable. We detailed relevant observations in lines 62-68. “Clinical examination revealed lateral neck swelling. Her blood pressure and heart rate were within normal range. However she did not require additional oxygen support to maintain saturations above 92% and respiration rate was at 14 breaths per minute. Routine laboratory tests were all within normal limits. A chest x-ray showed minimal right pleural effusion which was conservatively managed, and she was discharged home with analgesia as she was clinically well.”

2) Q: When the patient was found to have right pleural effusion, how could you let her go home with only prescribing analgesic ? For me I would arrange further examination because it was very unusual.

R: Thank you very much for your valuable comment. As the patient was clinically stable and had minimal effusion, there was no indication to investigate further, as this is not the usual practice in our emergency department. The effusion would have been more extensively investigated with CT imaging if the patient was clinically unwell. Please find changes in lines 66-68. “A chest x-ray showed minimal right pleural effusion which was conservatively managed and she was discharged home with analgesia as she was clinically well”.

3) Q: Did you let the patient drink some oil before the surgery ?

R: Thank you for your comment. No oil or cream milk was administered preoperatively. Although several other authors have recommended a 6–8 oz mixture of milk and cream or olive oil given to the patient a few hours before surgery to help identify the leak at the time of operation, we do not use it routinely in our practice due to the inefficacy expected, in our experience.

Round 2

Reviewer 1 Report

Dear Editor and Authors,

I re-read and re-evaluated this revised manuscript and have examined the comments and corrections performed by the authors as per the reviewers suggestions. Indeed, the authors have tried and have addressed the comments well. I still am not convienced the yoga class could be the causative mechanism for the chylothorax in this young patients but I will let the surgical community decide! I am therefore satisfied to now recommend the publication of this case report. Wishing well to all.

Needs some minor expression and syntax editing.