The lymphatic system, made up of the spleen, thymus, lymph nodes, tonsils, adenoids, and Peyer patches in the small intestines and lymph channels, is an essential part of the immune system. Increasing the rate of flow of lymph through lymphatic channels facilitates the movement of leukocytes and other immunogenic cells to the site of infection. OMT may be especially helpful for patients who are at rest for long periods, during which the flow rate of this immunologically rich fluid is slowed. 

Knott et al⁵ demonstrated that lymphatic flow in the thoracic duct was significantly increased in real time with the use of the thoracic pump, abdominal pump, and physical activity in canines. Hodge et al⁶ reinforced the aforementioned research by demonstrating that a lymphatic pump technique (LPT), specifically the abdominal lymphatic pump (ALP), was able to significantly increase thoracic duct lymph flow in mongrel dogs. 

The use of LPT in humans has demonstrated an enhanced immune response.^6,7-9 The most effective of these pump techniques in moving both lymph and immune cells was ALP.^5,6 During the influenza pandemic of 1918-1920, DOs were using lymphatic techniques, but the specific techniques used are not fully known.¹⁰ The use of the ALP as a separate treatment seems to have its origins at a later date.¹¹ 

The initial findings from the COVID-19 pandemic from Wuhan China and the United States indicated that many patients admitted to the hospital had either leucopenia, lymphopenia, or both, with the worst cases of lymphopenia found in patients who died.^11,12-14 

OMT techniques have been investigated in animal models to assess their effects on immune cell populations. LPT performed on dogs was shown to increase leukocyte count when analyzed by flow cytometry, with similar increases seen in all leukocyte populations.⁶ Studies conducted on both dogs and rats showed that LPT enhanced the immune response by mobilizing increased levels of inflammatory cytokines, increasing lymph flow, and increased leukocyte counts in the thoracic duct lymph.^6,15,16 Hodge et al¹⁷ showed that these leukocytes were recruited from the gut-associated lymphoid tissue and were transported in the lymph during the use of LPT, but the effects were transient. This finding is important because this is where 70% to 80% of plasma cells in the human body are normally located. The number of leukocytes went from a resting state of approximately 5 million cells per minute to 150 million cells per minute while the dogs received LPT. Further investigation into these animal models showed that LPT can produce the same beneficial results multiple times, including increased lymphatic flow, leukocyte recruitment, and cytokine/chemokine flux.¹⁸ This movement of immune cells to other areas of the body may help boost insufficient immune responses to fight off viral infections. A study¹⁹ investigating the effect of ALP on the delivery of antibiotics in rats infected with Streptococcus pneumoniae demonstrated enhanced delivery and greater effectiveness, with 63% of rats free of disease when OMT was combined with antibiotics vs 25% when antibiotics and saline were administered without OMT. ALP, independent of antibiotics, still had the ability to make 13% of rats disease free at the end of the study when compared with 0% disease-free rats in the control/saline and sham/saline groups.¹⁹ 

One major complication of COVID-19 is the long length of hospital stays, with patients who will eventually recover staying a median length of 10 to 13 days.^13,20,21 In a randomized controlled clinical trial conducted by Noll et al,⁸ elderly patients treated with OMT for pneumonia had significantly shorter hospital stays and shortened duration of intravenous medication. In another randomized clinical trial, Noll et al⁹ found that patients hospitalized with pneumonia and treated with OMT had significantly reduced length of hospitalizations, intravenous antibiotics, mortality, and respiratory failure when compared with conventional care only. This study, however, found no significant differences in intention-to-treat analysis or between light touch and OMT. Unfortunately, neither of these studies used ALP, which is arguably the most effective technique for mobilizing the immune system to mount a more effective response to an invading pathogen.^5,6 

Another unique advantage OMT may have is the ability of the body to respond to a vaccine more effectively. In a clinical trial, Jackson et al⁷ saw an increase in hepatitis B titer in patients treated with OMT when compared with a control group (no OMT), who also received the vaccine. This finding suggested improved immune function with OMT, which may be useful when a vaccine is made available to the public. 

Previous studies elucidated the utility of OMT in a patient population with respiratory tract infections. Evidence to suggest that OMT is a useful treatment option for patients with respiratory tract infections includes animal studies,^5,6,15-19 showing increased movement of lymph and delivery of leukocytes to fight infection, as well as human clinical trial results,^7-9 showing shortened hospital stays and less need for antibiotics. So, the effects of using OMT for the pulmonary-compromised patient minimally includes the following goals and OMT techniques: 

We have both the opportunity and obligation to step in to treat COVID-19 patients with OMT, which seems to be underused in the current approach to this pandemic. We may be able to improve the lives of patients with this virus. OMT, especially the ALP technique, can be an adjunct to the standard care of these patients in clinics or hospitals. As these patients are being treated with OMT, several impact markers could easily be collected and evaluated toward a double-blind study to compare participants who receive adjunctive OMT with those who receive usual care only. Important markers would include the need for hospitalization for those receiving outpatient OMT, length of stay for hospitalized patients, the need for ventilator support, and death. While more research is being conducted on COVID-19 and its treatment options, OMT may be a valuable tool to use in this pandemic and warrants further investigation to improve outcomes for patients.