Contributed by Derek R. Austin, MS, CMT, Jolie Haun, PhD, EdS, LMT, and M.K. Brennan, MS, RN, LMBT

Do you know that lymphatic pump techniques (LPT) can enhance your massage practice? Immune response is central to maintaining health. However, health can be compromised when there is any delay in the immune response to a pathogen. Lymphatic flow is a key component in facilitating the immune response. Techniques that focus on lymphatic flow are effective adjunctive therapy in acute infection, as well as immune support.

Exercise, passive movement and manipulative techniques have been shown to increase lymph flow. Osteopaths have historically used osteopathic lymphatic pump techniques (LPT) to improve lymphatic circulation, reduce edema and combat infectious disease. However, until recently, there was no scientific evidence that LPT enhances function of the lymphatic and immune systems.

Lymphatic pump techniques may be familiar to readers, as these techniques are commonly used to treat edema. This month's Massage Therapy Foundation research column summarizes two recent reviews on the lymphatic and immune effects of lymphatic pump treatment. The first article, by Lisa Hodge and Fred Downey, "Lymphatic Pump Treatment Enhances the Lymphatic and Immune Systems," was published in the journal Experimental Biology and Medicine in October 2011. The second article, by Lisa Hodge, "Osteopathic Lymphatic Pump Techniques to Enhance Immunity and Treat Pneumonia," was published in the International Journal of Osteopathic Medicine in March 2012.

Lymphatic pump techniques, also known as lymphatic pump treatments, affect the lymphatic system and are a staple of osteopathic manipulative medicine. Leukocytes traveling in the blood and lymphatic system perform an important role in the body known as "immune surveillance," searching for foreign bodies that will trigger an immune response. Thus, it is important that the flow of lymph not be restricted, as it is in lymphedema. Skeletal muscle contraction, intestinal peristalsis and respiration are already known to increase lymphatic pressure and flow. Additionally, LPT may enhance lymphatic and venous drainage, improving immune surveillance during times of infection.

Despite slowly mounting research evidence, the question remains: Is LPT helpful for infection? Small sample sizes limit the validity of pilot studies that suggest LPT can enhance innate immunity in patients with acute infection and healthy individuals. Though we often refer to human studies to give guidance on effective treatments, laboratory-based animal studies (often referred to as "basic" or "bench" research) also inform the mechanisms and efficacy of modalities such as LPT. Animal studies have demonstrated that abdominal and thoracic pumping increase thoracic duct flow in dogs and rats.

These animal studies point toward lymphatic pump treatments enhancing the uptake of lymph into the lymphatic system, thus increasing the immune function of this system. Previous research on anesthetized dogs by Hodge and her collaborators has shown that four minutes of abdominal lymphatic pump treatment may increase the flow of immune cells from both the innate and adaptive immune systems. That research showed LPT can mobilize white blood cells and other immune cells from GI tissue into lymph. Other research on dogs has found similar results whereby LPT to the abdomen mobilizes immune cells from the mesentery, though the effect sizes and clinical relevance are less well-established.

The lymphatic flux, or molecules per minute of lymph collected, of additional inflammatory mediators such as interleukins and cytokines, are also enhanced by LPT when measured during four minutes of LPT, when compared to the time immediately pre-LPT and 10 minutes post-LPT. Also, LPT improves thoracic duct leukocyte flux without increasing mean arterial pressure, at least under the condition of anesthesia.

More recent research in Hodge's laboratory has focused on a rat model employing LPT to the abdomen at a rate of one compression per second for four minutes. As in dogs, LPT in rats temporarily increases lymph flow and concentrations of immune cells, suggesting that LPT boosts immune surveillance. LPT releases mature, activated lymphocytes, including IgA+ and IgG+ B cells into both thoracic and mesenteric lymph. However, this canine and rodent research has only looked at abdominal LPT due to technical difficulties with performing thoracic LPT in the controlled experimental setting, so the effects of thoracic LPT in these animal models is still unknown.

However, thoracic LPT has been shown in a few studies to enhance antibody response in humans. Hodge points out the need for further experimentation to clarify the differences between abdominal and thoracic LPT.

Hodge, Downey and a group of collaborators used a rat model of pneumonia to study whether LPT improves lymphatic clearance of pneumococcal bacteria. In this study, 20 rats received four minutes of daily anesthetized LPT, another 20 rats received daily anesthesia and a sham treatment of light touch, and another 20 rats served as controls. Eight days after infection, the researchers found that the amount of S. pneumoniae bacteria in the lungs was significantly reduced in both treatment groups compared to control. Compared to the sham treatment, LPT led to an even higher amount of bacteria clearance.

The treated rats also exhibited fewer immune cells in the lungs, indicating their infections were improved compared to the controls. While this article focuses on the effects of LPT, it is interesting that light touch also had a significant effect compared to control. Light touch is often used as a "sham treatment" comparison group compared to a form of massage or bodywork. If light touch has a therapeutic effect, then it may not serve as a good control or comparison group.

In humans, LPT is used as an adjunct therapy to improve cleansing of the bronchi and trachea, increase sputum production and shorten the duration of cough in patients with lower respiratory disease, such as pneumonia.

The most significant recent research into LPT in humans is the Multi-Center Osteopathic Study in the Elderly (MOPSE). This randomized, double-blind, controlled trial compared light-touch, osteopathic manipulative therapy (OMT) and traditional care. The study involved 406 hospitalized elderly patients with pneumonia who were followed for outcomes including length of hospital stay, antibiotic use and respiratory failure or death.

As may be expected with many forms of bodywork, OMT led to a significantly higher report of increased musculoskeletal pain, compared to light touch and traditional care. While the MOPSE intention-to-treat analysis, which includes those randomized to receive OMT who may or may not have actually received it, did not show any significant differences between groups, the results were different for those who actually received OMT.

In that statistical breakdown, referred to as a per-protocol analysis, patients who received OMT plus conventional care had decreased length of hospital stay, duration of IV antibiotics and frequency of respiratory failure or death compared to the conventional care group alone.

Future research may illuminate other interesting benefits of LPT. Another rodent study by Hodge and various collaborators showed LPT partially prevented the development of pulmonary tumors in rats implanted with tumor cells. The amount of solid tumors was reduced by 30% and the number of immune cells, including B-cells, T-cells, NK cells and macrophages in the lungs, increased. Additionally, historical data from the H1N1 flu pandemic of 1917-1918 shows treatment under the care of an osteopathic physician significantly decreased mortality, especially in patients who had influenza complicated by pneumonia. Osteopathic manipulative medicine of this era already included lymphatic pump treatments that have only been studied rigorously in the 21st century.

The way by which LPT enhances immune system function and patient outcomes appears to be through at least two major mechanisms. LPT improves immunological memory, which may aid in the clearance of pathogens and prevent chronic infection. LPT also increases pulmonary trafficking of gastrointestinal immune cells, possibly providing immune protection in the lungs. Despite these benefits of LPT, other studies have had less-positive results. One study showed LPT does not increase serum interferon levels in healthy individuals, though interferon is not normally elevated in healthy people. A clinical trial also showed mild, but significant worsening of lung function in patients with COPD following LPT. Subjectively, however, the patients reported feeling better after LPT. And while LPT has been shown in some studies to enhance the immune-system response to vaccination, it did not increase antibody titers against influenza in a recent human study.

The development of antibiotic-resistant bacteria, including MRSA and resistant forms of pneumonia, has led to a serious search for non-antibiotic methods of treating infectious disease. While the research evidence is generally preliminary, laboratory and clinical studies are beginning to show that LPT has a significant immune-boosting effect. It is still unknown what quantitative effect LPT has, especially in humans, and particularly for diseases other than pneumonia. Furthermore, some studies confound LPT with other manipulative medicine techniques that may not be in the scope of practice of massage therapists.

Overall, with research showing significant results when LPT is applied for a duration of only four minutes, it may be an easy technique to incorporate into a massage session with proper training. Of course, some clients may not want their abdomens vigorously pumped. However, the health benefits may convince them otherwise.

These data provide important implications for the application of LPT in clinical practice, particularly when immune effects are a desired outcome. Furthermore, these findings provide a solid scientific basis, including both basic and applied research, to support the use of LPT when making treatment recommendations to clients and patients. These published findings support the field of massage therapy and bodywork in the clinical setting as professionals and research scientists continue to establish the scientific merit of modalities such as LPT.

One of the two reviews discussed in this article is available for free in PubMed Central. To learn more about the effects of modalities such as LPT, you can review the Massage Therapy Foundation article archives, read accepted MTF Research Grant abstracts, or search PubMed for massage therapy studies.