Live to Move and Move to Live: The Health of the Lymphatic System Relies on Mobility and the Foot and Calf Pump Connection

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript 'Live to Move and Move to Live: The health of the lymphatic system relies on mobility and the foot and calf pump connection' by Barnhart addresses a highly relevant and understudied field. It summarizes the history and basic principles of venous and lymphatic vessel diseases.

However, important and highly relevant topics are not addressed in this manuscript and need to be included in a revised version:

- New/updated starling principle: This is of high relevance as most of extravasated fluid is uptaken by the lymphatics and transported back to the venous circulation.

- a short paragraph on the difference between upper and lower limb lymphatic function would be helpful for the reader

- provide more information on the lymphatic anatomy and lymphedema. Compared to CVI there is a discrepency.

- There is no figure highlighting the content of the manuscript. At least one figure should be included!

- 1 paragraph on causes for lymphatic diseases (primary and secondary) would improve the manuscript

Comments on the Quality of English Language

Only minor corrections/typos required.

Author Response

- New/updated starling principle: This is of high relevance as most of extravasated fluid is uptaken by the lymphatics and transported back to the venous circulation.

Added to manuscript starting with line 39

- a short paragraph on the difference between upper and lower limb lymphatic function would be helpful for the reader

Not included; leg/foot function described which is focus on this article

- provide more information on the lymphatic anatomy and lymphedema. Compared to CVI there is a discrepency.

Did not expand on this

- There is no figure highlighting the content of the manuscript. At least one figure should be included!

Added Figure 1, calf muscle pump effects on venous return (from Koya Medical Inc.)

- 1 paragraph on causes for lymphatic diseases (primary and secondary) would improve the manuscript

Added starting with line 26

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

Line 76 needs better support;;"Chronic venous insufficiency is often caused by calf muscle pump failure"

consider reviewing and adding this reference;

J Vasc Surg . 1994 Dec;20(6):872-7; discussion 878-9.  doi: 10.1016/0741-5214(94)90223-2.

The significance of calf muscle pump function in venous ulceration

C T Araki ¹, T L Back, F T Padberg, P N Thompson, Z Jamil, B C Lee, W N Duran, R W Hobson 2nd Affiliations expand

• PMID: 7990181
 
• DOI: 10.1016/0741-5214(94)90223-

Starting at line 87 describes Guyton principle, may want to include reference to this;

Jamalian, S., Jafarnejad, M., Zawieja, S.D. et al. Demonstration and Analysis of the Suction Effect for Pumping Lymph from Tissue Beds at Subatmospheric Pressure. Sci Rep 7, 12080 (2017). https://doi.org/10.1038/s41598-017-11599-x

At line 163, consider adding short paragraph on obesity contributing to lower extremity lymphatic and venous dysfunction given the obesity/elevated BMI as significant clinical/society component

Potential resource

Kataru RP, Park HJ, Baik JE, Li C, Shin J and Mehrara BJ (2020) Regulation of Lymphatic Function in Obesity. Front. Physiol. 11:459. doi: 10.3389/fphys.2020.00459

Line 163/164 looks as start of Conclusion/summary paragraph, would list as such

Add in weight loss, BMI modification line 170 as another important factor

Author Response

Reviewer 2:

-Line 76 needs better support;;"Chronic venous insufficiency is often caused by calf muscle pump failure" consider reviewing and adding this reference;

J Vasc Surg   

. 1994 Dec;20(6):872-7; discussion 878-9.  doi: 10.1016/0741-5214(94)90223-2.

The significance of calf muscle pump function in venous ulceration

C T Araki ¹, T L Back, F T Padberg, P N Thompson, Z Jamil, B C Lee, W N Duran, R W Hobson 2nd Affiliations expand  PMID: 7990181  DOI: 10.1016/0741-5214(94)90223-

Revised and added at line 107

-Starting at line 87 describes Guyton principle, may want to include reference to this;

Jamalian, S., Jafarnejad, M., Zawieja, S.D. et al. Demonstration and Analysis of the Suction Effect for Pumping Lymph from Tissue Beds at Subatmospheric Pressure. Sci Rep 7, 12080 (2017). https://doi.org/10.1038/s41598-017-11599-x

Added reference at line 125

-At line 163, consider adding short paragraph on obesity contributing to lower extremity lymphatic and venous dysfunction given the obesity/elevated BMI as significant clinical/society component

Potential resource:  Kataru RP, Park HJ, Baik JE, Li C, Shin J and Mehrara BJ (2020) Regulation of Lymphatic Function in Obesity. Front. Physiol. 11:459. doi: 10.3389/fphys.2020.00459

Added related content and references starting at line 192

-Line 163/164 looks as start of Conclusion/summary paragraph, would list as such

Done, line 217

-Add in weight loss, BMI modification line 170 as another important factor

Done, line 224

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The selected issue is of great importance. The authors have done a good job describing the significance of the interconnection between the lymphatic and venous systems, as well as the venous pump function. However, although the paper is not a review article, the description of the muscle pump and venous physiology is not comprehensive, and some recently published data are missing. I would recommend that the paper be revised.

1.     Page 2 line 53: The term 'long saphenous vein' has been changed to 'great saphenous vein' in accordance with modern anatomical nomenclature. (Kachlik D, Pechacek V, Baca V, Musil V. The superficial venous system of the lower extremity: new nomenclature. Phlebology. 2010 Jun;25(3):113-23. doi: 10.1258/phleb.2009.009046. PMID: 20483860.)

2.     Page 2 line 54: The term 'short saphenous vein' should be changed to 'small saphenous vein' in accordance with modern anatomical nomenclature. (Kachlik D, Pechacek V, Baca V, Musil V. The superficial venous system of the lower extremity: new nomenclature. Phlebology. 2010 Jun;25(3):113-23. doi: 10.1258/phleb.2009.009046. PMID: 20483860.)

3.     Page 2 line 70-72: Although this conception is widespread, new published data on muscle pump physiology contradicts it. The muscle pump functions differently during natural locomotion compared to artificial maneuvers such as plantar flexion exercises. The muscle pump is not solely a mechanism of the posterior calf muscle group. It involves the synergistic work of antagonist muscles and the ankle joint. During the stance phase, the gastrocnemius contracts while the anterior tibial muscle relaxes, generating high pressure in intramuscular veins. Conversely, during the swing phase of the gait cycle, the anterior tibial muscle contracts while the gastrocnemius relaxes, generating very low or even negative pressure in the intramuscular veins. The pump redirects blood flow from superficial to intramuscular veins during natural locomotion, acting like a stream diversion pump. (Tauraginskii et al., 2023) (Human lower leg muscle pump acts like a stream diversion pump during locomotion. Roman A. Tauraginskii, Fedor Lurie, Sergei Simakov, Rishal Agalarov, Pavel Khramtsov, Maxim Babushkin, Denis Borsuk, Maxim Galchenko. bioRxiv 2023.09.25.559436; doi: https://doi.org/10.1101/2023.09.25.559436).

Please use the seminal papers that first described this mechanism instead of the inappropriate reference #2 ^{(Arnoldi, 1966; HOJENSGARD et al., 1952; Kuiper, 1966; POLLACK & TAYLOR, 1949; Stegall, 1966)}

4.     Page 2 line 74-75: The described concept has not proven to be enduring. The initial studies reported various relationships between functional tests that assess the muscle pump's ability to eject blood and AVP and/or disease severity, ranging from negligible (K. et al., 2005; Tachibana et al., 2004) to moderate. (D. Christopoulos et al., 1988; D. G. Christopoulos et al., 1987; Labropoulos et al., 1996; Welkie, Comerota, Katz, et al., 1992; Welkie, Comerota, Kerr, et al., 1992). Recent studies have shown a weak correlation between ejection fraction (EF) and residual volume fraction (RVF) with either AVP or disease severity. (Raju et al., 2019; Williams et al., 2014) Furthermore, efforts to enhance CMP function through resistance exercise programs have demonstrated a lack of correlation between clinical outcomes and improvements in CMP functional parameters.(Araujo et al., 2016, 2023; Qiu et al., 2022; Smith et al., 2018; Williams et al., 2014)

5.     Page 3 line 104-107: the venous sinus acts as a conduit rather than a reservoir. It transfers blood from the network of intramuscular veins to the axial deep veins. (Tauraginskii et al., 2023)

6.     Page 3 line 118-120: The mechanism and numbers described pertain to the diversity of artificial maneuvers, such as plantar flexion, Parana, IPC, NMES, etc., and are not related to natural human ambulation. Please add the particular maneuvers related to the described data.

7.     Page 3 line 120-121: The statement is incorrect. Any movement or acceleration is the result of force, as stated in the second law of Newton. Since blood is a continuous medium, we use a special case of the energy conservation law, known as Poiseuille's equation, to describe blood movement. In simpler terms, blood moves from areas of higher pressure to areas of lower pressure. Blood flows into the right atrium due to the higher venous or lymph pressure at the distal point, regardless of body position ^{(HOJENSGARD et al., 1952; OCHSNER et al., 1951; POLLACK & TAYLOR, 1949; Pollack & Wood, 2017)}. Fluid pressure is a complex parameter that includes dynamic pressure resulting from the heart's force and static pressure, which includes hydrostatic pressure due to gravity.  Gravity is a force that acts on each atom of fluid equally at the same level (Landau & Lifshitz, 1987). Therefore, the hydrostatic component of pressure in arteries, capillaries, veins, and lymph is equal. There is no reason to overcome the hydrostatic component of pressure.

8.     Page 3 line 127-128: Please correct the statement: Venous reflux is caused by valve incompetence, which can result from congenital, primary, or secondary (thrombosis) diseases. The muscle pump is the driving force behind retrograde blood flow (venous reflux) in case of valves incompetence. (Tauraginskii et al., 2021, 2023).  

9.     Page 4 line 155: Please provide a reference to support the statement that ET improves venous reflux or remove it.

10.  Page 4 line 157: The studies have shown a weak correlation between ejection fraction (EF) and residual volume fraction (RVF) with either AVP or disease severity. (Raju et al., 2019; Williams et al., 2014) Furthermore, efforts to enhance CMP function through resistance exercise programs have demonstrated a lack of correlation between clinical outcomes and improvements in CMP functional parameters.(Araujo et al., 2016, 2023; Qiu et al., 2022; Smith et al., 2018; Williams et al., 2014)

Araujo, D. N., Ribeiro, C. T. D., Maciel, A. C. C., Bruno, S. S., Fregonezi, G. A. F., & Dias, F. A. L. (2023). Physical exercise for the treatment of non‐ulcerated chronic venous insufficiency. Cochrane Database of Systematic Reviews, 6. https://doi.org/10.1002/14651858.CD010637.pub3

Araujo, D. N., Ribeiro, C. T., Maciel, A. C., Bruno, S. S., Fregonezi, G. A., & Dias, F. al. (2016). Physical exercise for the treatment of non-ulcerated chronic venous insufficiency. Cochrane Database of Systematic Reviews, 2016(12). https://doi.org/10.1002/14651858.CD010637.pub2

Arnoldi, C. C. (1966). On the Conditions for the Venous Return From the Lower Leg in Healthy Subjects and in Patients With Chronic Venous Insufficiency. Angiology, 17(3), 153–171. https://doi.org/10.1177/000331976601700303

Christopoulos, D. G., Nicolaides, A. N., Szendro, G., Irvine, A. T., Bull, M. I., & Eastcott, H. H. G. (1987). Air-plethysmography and the effect of elastic compression on venous hemodynamics of the leg. Journal of Vascular Surgery, 5(1), 148–159. https://doi.org/10.1016/0741-5214(87)90205-9

Christopoulos, D., Nicolaides, a N., & Szendro, G. (1988). Venous reflux: quantification and correlation with the clinical severity of chronic venous disease. The British Journal of Surgery, 75(4), 352–356. http://www.ncbi.nlm.nih.gov/pubmed/3359149

HOJENSGARD, I. C., STURUP, H., & HOJENSGARD IC, S. H. (1952). Static and Dynamic Pressures in Superficial and Deep Veins of the Lower Extremity in Man. Acta Physiologica Scandinavica, 27(1), 49–67. https://doi.org/10.1111/j.1748-1716.1953.tb00923.x

K., P. S. P., J., T. A., M., L. N. J., F., B. P. R., & W., B. W. (2005). Venous assessment using air plethysmography: A comparison with clinical examination, ambulatory venous pressure measurement and duplex scanning. British Journal of Surgery, 80(8), 967–970. https://doi.org/10.1002/bjs.1800800808

Kuiper, JP. P. (1966). Venous pressure determination (direct method). Dermatologica, 132(2), 206-17. https://doi.org/10.1159/000254421

Labropoulos, N., Giannoukas, A. D., Nicolaides, A. N., Veller, M., Leon, M., & Volteas, N. (1996). The role of venous reflux and calf muscle pump function in nonthrombotic chronic venous insufficiency. Correlation with severity of signs and symptoms. Archives of Surgery (Chicago, Ill. : 1960), 131(4), 403–406. https://doi.org/10.1001/archsurg.1996.01430160061011

Landau, L. D., & Lifshitz, E. M. (1987). Fluid mechanics: Landau and Lifshitz: course of theoretical physics. In Image Rochester NY (Vol. 6, Issue 1). https://doi.org/10.1007/b138775

OCHSNER, A., COLP, R., & BURCH, G. E. (1951). Normal blood pressure in the superficial venous system of man at rest in the supine position. Circulation. https://doi.org/10.1161/01.CIR.3.5.674

POLLACK, A. A., & TAYLOR, B. E. (1949). The effect of exercise and body position on the venous pressure at the ankle in patients having venous valvular defects. The Journal of Clinical Investigation, 28(3), 559–563.

Pollack, A. A., & Wood, E. H. (2017). Venous Pressure in the Saphenous Vein at the Ankle in Man during Exercise and Changes in Posture. Journal of Applied Physiology. https://doi.org/10.1152/jappl.1949.1.9.649

Qiu, Y., Osadnik, C. R., Team, V., & Weller, C. D. (2022). Effects of physical activity as an adjunct treatment on healing outcomes and recurrence of venous leg ulcers: A scoping review. Wound Repair and Regeneration, 30(2), 172–185. https://doi.org/https://doi.org/10.1111/wrr.12995

Raju, S., Knepper, J., May, C., Knight, A., Pace, N., & Jayaraj, A. (2019). Ambulatory venous pressure, air plethysmography, and the role of calf venous pump in chronic venous disease. Journal of Vascular Surgery: Venous and Lymphatic Disorders, 7(3), 428–440. https://doi.org/https://doi.org/10.1016/j.jvsv.2018.08.009

Smith, D., Lane, R., McGinnes, R., O’Brien, J., Johnston, R., Bugeja, L., Team, V., & Weller, C. (2018). What is the effect of exercise on wound healing in patients with venous leg ulcers? A systematic review. International Wound Journal, 15(3), 441–453. https://doi.org/https://doi.org/10.1111/iwj.12885

Stegall, H. F. (1966). Muscle Pumping in the Dependent Leg. Circulation Research, 19(1), 180–190. https://doi.org/10.1161/01.res.19.1.180

Tachibana, M., Hiroe, T., Kanaoka, Y., & Ohgi, S. (2004). Quantitative air-plethysmographic venous function and ambulatory venous pressure in patients with primary varicose vein. International Angiology.

Tauraginskii, R. A., Lurie, F., Simakov, S., & Agalarov, R. (2021). Venous reflux in the great saphenous vein is driven by a suction force provided by the calf muscle pump in the compression–decompression maneuver. Journal of Vascular Surgery: Venous and Lymphatic Disorders, 9(5), 1282–1290. https://doi.org/https://doi.org/10.1016/j.jvsv.2020.12.070

Tauraginskii, R. A., Lurie, F., Simakov, S., Agalarov, R., Borsuk, D., & Khramtsov, P. (2023). Calf muscle pump pressure-flow cycle during ambulation. Journal of Vascular Surgery: Venous and Lymphatic Disorders, 11(4), 783-792.e7. https://doi.org/10.1016/j.jvsv.2023.04.002

Welkie, J. F., Comerota, A. J., Katz, M. L., Aldridge, S. C., Kerr, R. P., & White, J. V. (1992). Hemodynamic deterioration in chronic venous disease. Journal of Vascular Surgery, 16(5), 733–740. https://doi.org/10.1016/0741-5214(92)90228-Z

Welkie, J. F., Comerota, A. J., Kerr, R. P., Katz, M. L., Jayheimer, E. C., & Brigham, R. A. (1992). The Hemodynamics of Venous Ulceration. Annals of Vascular Surgery, 6(1), 1–4. https://doi.org/10.1007/BF02000658

Williams, K. J., Ayekoloye, O., Moore, H. M., & Davies, A. H. (2014). The calf muscle pump revisited. Journal of Vascular Surgery: Venous and Lymphatic Disorders, 2(3), 329–334. https://doi.org/10.1016/j.jvsv.2013.10.053

Author Response

Reviewer 3:

The selected issue is of great importance. The authors have done a good job describing the significance of the interconnection between the lymphatic and venous systems, as well as the venous pump function. However, although the paper is not a review article, the description of the muscle pump and venous physiology is not comprehensive, and some recently published data are missing. I would recommend that the paper be revised.

1. Page 2 line 53: The term 'long saphenous vein' has been changed to 'great saphenous vein' in accordance with modern anatomical nomenclature. (Kachlik D, Pechacek V, Baca V, Musil V. The superficial venous system of the lower extremity: new nomenclature. Phlebology. 2010 Jun;25(3):113-23. doi: 10.1258/phleb.2009.009046. PMID: 20483860.)

Done, line 67

2. Page 2 line 54: The term 'short saphenous vein' should be changed to 'small saphenous vein' in accordance with modern anatomical nomenclature. (Kachlik D, Pechacek V, Baca V, Musil V. The superficial venous system of the lower extremity: new nomenclature. Phlebology. 2010 Jun;25(3):113-23. doi: 10.1258/phleb.2009.009046. PMID: 20483860.)

Done, line 68

3. Page 2 line 70-72: Although this conception is widespread, new published data on muscle pump physiology contradicts it. The muscle pump functions differently during natural locomotion compared to artificial maneuvers such as plantar flexion exercises. The muscle pump is not solely a mechanism of the posterior calf muscle group. It involves the synergistic work of antagonist muscles and the ankle joint. During the stance phase, the gastrocnemius contracts while the anterior tibial muscle relaxes, generating high pressure in intramuscular veins. Conversely, during the swing phase of the gait cycle, the anterior tibial muscle contracts while the gastrocnemius relaxes, generating very low or even negative pressure in the intramuscular veins. The pump redirects blood flow from superficial to intramuscular veins during natural locomotion, acting like a stream diversion pump. (Tauraginskii et al., 2023) (Human lower leg muscle pump acts like a stream diversion pump during locomotion. Roman A. Tauraginskii, Fedor Lurie, Sergei Simakov, Rishal Agalarov, Pavel Khramtsov, Maxim Babushkin, Denis Borsuk, Maxim Galchenko. bioRxiv 2023.09.25.559436; doi: https://doi.org/10.1101/2023.09.25.559436).

Added and rewritten starting at line 93

Please use the seminal papers that first described this mechanism instead of the inappropriate reference #2 (Arnoldi, 1966; HOJENSGARD et al., 1952; Kuiper, 1966; POLLACK & TAYLOR, 1949; Stegall, 1966)

Done, included references line 87

4. Page 2 line 74-75: The described concept has not proven to be enduring. The initial studies reported various relationships between functional tests that assess the muscle pump's ability to eject blood and AVP and/or disease severity, ranging from negligible (K. et al., 2005; Tachibana et al., 2004) to moderate. (D. Christopoulos et al., 1988; D. G. Christopoulos et al., 1987; Labropoulos et al., 1996; Welkie, Comerota, Katz, et al., 1992; Welkie, Comerota, Kerr, et al., 1992). Recent studies have shown a weak correlation between ejection fraction (EF) and residual volume fraction (RVF) with either AVP or disease severity. (Raju et al., 2019; Williams et al., 2014) Furthermore, efforts to enhance CMP function through resistance exercise programs have demonstrated a lack of correlation between clinical outcomes and improvements in CMP functional parameters.(Araujo et al., 2016, 2023; Qiu et al., 2022; Smith et al., 2018; Williams et al., 2014)

Attempted to include but kept it simple to prevent complete rewrite

5. Page 3 line 104-107: the venous sinus acts as a conduit rather than a reservoir. It transfers blood from the network of intramuscular veins to the axial deep veins. (Tauraginskii et al., 2023)

Done, line 140

6. Page 3 line 118-120: The mechanism and numbers described pertain to the diversity of artificial maneuvers, such as plantar flexion, Parana, IPC, NMES, etc., and are not related to natural human ambulation. Please add the particular maneuvers related to the described data.

Done, line 156

7. Page 3 line 120-121: The statement is incorrect. Any movement or acceleration is the result of force, as stated in the second law of Newton. Since blood is a continuous medium, we use a special case of the energy conservation law, known as Poiseuille's equation, to describe blood movement. In simpler terms, blood moves from areas of higher pressure to areas of lower pressure. Blood flows into the right atrium due to the higher venous or lymph pressure at the distal point, regardless of body position (HOJENSGARD et al., 1952; OCHSNER et al., 1951; POLLACK & TAYLOR, 1949; Pollack & Wood, 2017). Fluid pressure is a complex parameter that includes dynamic pressure resulting from the heart's force and static pressure, which includes hydrostatic pressure due to gravity. Gravity is a force that acts on each atom of fluid equally at the same level (Landau & Lifshitz, 1987). Therefore, the hydrostatic component of pressure in arteries, capillaries, veins, and lymph is equal. There is no reason to overcome the hydrostatic component of pressure.

Removed wording ‘gravity-induced’ to address above, line 158

8. Page 3 line 127-128: Please correct the statement: Venous reflux is caused by valve incompetence, which can result from congenital, primary, or secondary (thrombosis) diseases. The muscle pump is the driving force behind retrograde blood flow (venous reflux) in case of valves incompetence. (Tauraginskii et al., 2021, 2023).

Done, line 164

9. Page 4 line 155: Please provide a reference to support the statement that ET improves venous reflux or remove it.

Added reference, line 209

10. Page 4 line 157: The studies have shown a weak correlation between ejection fraction (EF) and residual volume fraction (RVF) with either AVP or disease severity. (Raju et al., 2019; Williams et al., 2014) Furthermore, efforts to enhance CMP function through resistance exercise programs have demonstrated a lack of correlation between clinical outcomes and improvements in CMP functional parameters.(Araujo et al., 2016, 2023; Qiu et al., 2022; Smith et al., 2018; Williams et al., 2014)

Emphasized walking, natural gait, line 211

Added highlighted references (thank you for including these).

Arnoldi, C. C. (1966). On the Conditions for the Venous Return From the Lower Leg in Healthy Subjects and in Patients With Chronic Venous Insufficiency. Angiology, 17(3), 153–171. https://doi.org/10.1177/000331976601700303

HOJENSGARD, I. C., STURUP, H., & HOJENSGARD IC, S. H. (1952). Static and Dynamic Pressures in Superficial and Deep Veins of the Lower Extremity in Man. Acta Physiologica Scandinavica, 27(1), 49–67. https://doi.org/10.1111/j.1748-1716.1953.tb00923.x

Kuiper, JP. P. (1966). Venous pressure determination (direct method). Dermatologica, 132(2), 206-17. https://doi.org/10.1159/000254421

POLLACK, A. A., & TAYLOR, B. E. (1949). The effect of exercise and body position on the venous pressure at the ankle in patients having venous valvular defects. The Journal of Clinical Investigation, 28(3), 559–563.

Stegall, H. F. (1966). Muscle Pumping in the Dependent Leg. Circulation Research, 19(1), 180–190. https://doi.org/10.1161/01.res.19.1.180

Tauraginskii, R. A., Lurie, F., Simakov, S., & Agalarov, R. (2021). Venous reflux in the great saphenous vein is driven by a suction force provided by the calf muscle pump in the compression–decompression maneuver. Journal of Vascular Surgery: Venous and Lymphatic Disorders, 9(5), 1282–1290. https://doi.org/https://doi.org/10.1016/j.jvsv.2020.12.070

Tauraginskii, R. A., Lurie, F., Simakov, S., Agalarov, R., Borsuk, D., & Khramtsov, P. (2023). Calf muscle pump pressure-flow cycle during ambulation. Journal of Vascular Surgery: Venous and Lymphatic Disorders, 11(4), 783-792.e7. https://doi.org/10.1016/j.jvsv.2023.04.002

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for the revised manuscript.

The paragraph on primary lymphoedema needs to be rewritten. Classifying lymphoedema in 3 categories does not respresent the current state of knowledge and classification. Please include and cite Gordon et al. and integrate this into the text.

Gordon K, Varney R, Keeley V, Riches K, Jeffery S, Van Zanten M, Mortimer P, Ostergaard P, Mansour S. Update and audit of the St George's classification algorithm of primary lymphatic anomalies: a clinical and molecular approach to diagnosis. J Med Genet. 2020 Oct;57(10):653-659. doi: 10.1136/jmedgenet-2019-106084. Epub 2020 May 14. PMID: 32409509; PMCID: PMC7525776.

Lymphoedema praecox, tarda etc is no modern classification anymore.

Author Response

I updated the primary lymphedema content based upon the article by Gordon et al., and the updates are in blue highlight starting on line 27.  Thank you!

Reviewer 3 Report

Comments and Suggestions for Authors

Thanks for the extensive revision. The paper looks better.

Author Response

Thank you for your input to improve the manuscript.