The physiology of thoracic duct pressure and flow: A review of the literature.
Level 5 - mechanism / opinion, no new human data
Systematic review synthesizing animal and descriptive human physiological studies
PubMed 41572961 · doi:10.14814/phy2.70742
What was done
A PRISMA-compliant systematic review of MEDLINE, Embase, and Google Scholar was conducted through August 2025 without language restrictions. The review evaluated the effects of respiration, circulation, and intrinsic contractility on thoracic duct (TD) lymph flow and pressure in humans and non-human mammals.
What was found
Across 23 included studies (6 human, 17 animal): - Respiratory activity influenced TD flow and/or pressure in 5 of 6 human studies and 12 of 17 animal studies. - Circulatory influences were identified in 3 of 6 human studies and 8 of 17 animal studies. - Intrinsic TD contractility was reported as an independent contributor to lymph propulsion in 3 of 6 human studies and 6 of 17 animal studies. - Reported effects ranged from absent to highly synchronous physiological coupling, with no quantitative pooled estimates reported.
Why it matters
This review synthesizes the physiological mechanisms driving central lymphatic return, demonstrating that respiratory, circulatory, and intrinsic vascular forces all contribute but remain inconsistently quantified.
Limits
The evidence base is small and predominantly non-human (17 of 23 studies). Substantial methodological heterogeneity and lack of standardized physiological measurement protocols across the literature preclude definitive quantitative conclusions.