The utilization of mechanical ventilation (MV) among patients receiving intensive care is notably high, recorded at 53.6% in a Japanese retrospective database study in intensive care unit (ICU) environments1. Clinically, the use of MV can be implemented through either invasive or non-invasive approaches2. Acute respiratory failure, incidences of pulmonary disease, traumatic brain injury, stroke, coma, neuromuscular disorders, surgery, or general anesthesia are conditions commonly affiliated with the implementation of MV3,4. Current clinical evidence ascribes poor survival outcomes, increased disease severity, augmented mortality rates, significant economic burdens, and higher ICU costs to the use of MV5,6. Furthermore, patients often experience a range of adverse effects following mechanical ventilation (MV). These effects usually include complications related to muscle weakness in limbs and inspiratory muscles, disruptions in sleep patterns, and the onset of ICU delirium, all of which significantly impact the overall well-being of a patient7, 8, 9, 10. Patient well-being also extends to the financial aspects of their treatment, and in this regard, the use of MV is directly associated with a 25% increase in the total daily costs of ICU care11. Furthermore, the duration of an ICU stay is significantly influenced by the successful cessation of mechanical ventilation (MV). However, the process of terminating MV use is reliant on effective weaning of patients from MV, which is a gradual process that requires the explicit application of stringent protocols12. To this end, difficulties in weaning patients from MV can occur in up to 23% of critically ill patients, significantly contributing to poorer patient outcomes13. Extended use of MV significantly increases the likelihood of developing various complications, including muscle weakness, sepsis, candidemia, pulmonary embolism, blood clots, hyperactive delirium, the requirement for vasoactive therapy, parenteral nutrition, and elevated mortality rates12,14. Furthermore, the extended application of MV can lead to the onset of post-ICU weakness which is commonly characterized by muscle and nerve dysfunction. This weakness, in turn, plays a role in the development of post-ICU syndrome, a complex set of physical and psychological issues that negatively affect individuals after they have been discharged from the ICU15. The incidence and severity of these detrimental effects should not be overlooked, and the importance of finding effective interventions specifically directed at reducing the total duration of MV use is highlighted, as these measures are essential to improving patient outcomes.

From a clinical perspective, to both reduce the duration of MV and mitigate the related risks, it is crucial to effectively implement the ABCDE bundle protocol. This protocol implements specific procedures aimed at initiating and applying particular awakening techniques, breathing coordination, delirium monitoring/management, early exercise and mobility performance, as well as inspiratory muscle training7,16. Supplementary interventions aimed at reducing the duration of MV use have been explored, and include placing patients in a prone position, initiating early physical therapy, music intervention, vitamin treatment, and antioxidant supplementation17, 18, 19, 20, 21, 22.

The use of acupuncture in the treatment of various medical conditions has been recorded over thousands of years (including postoperative acute pain, nausea and vomiting, delirium, etc.) whereby its safety and efficacy are clinically recognized23, 24, 25, 26, 27, 28. The application of any intervention that can effectively reduce the length of MV use, or improve the function thereof, would provide substantial support in negating or ameliorating the associated injurious effects of MV. At present, acupuncture therapy is not integrated into the standard array of commonly utilized treatments in the ICU due to the absence of compelling evidence supporting its efficacy in this specific clinical context. However, current evidence explicitly suggests that acupuncture treatment is definitively associated with minimal adverse events, and may provide potential benefit to patients in various clinical settings23. A systematic review and meta-analysis on the safety of acupuncture in the ICU did not find higher adverse events following acupuncture compared to routine ICU care. The finding also indicates a reduction in ICU stay and 28-day mortality in the acupuncture arm29. Formenti et al. investigated the role of acupuncture in the ICU in a systematic review, the study concluded that acupuncture is acceptable and feasible in the ICU settings and highlighted that acupuncture might be able to assist in nutritional support, recovery after critical illness, cardiovascular shock, respiratory function, pain and sedation30. The role of acupuncture as a perioperative treatment has been associated with various added advantages, such as offering postoperative pain relief and preventing nausea and vomiting25,26. Regarding acupuncture treatment in the context of mechanical ventilation (MV) use in an ICU setting, Asmussen et al., conducted a meta-analysis on electroacupuncture (EA) for anesthesia during cardiac surgery. Their findings indicated a significant reduction in postoperative MV duration and ICU stay time following EA31. While Asmussen et al.'s meta-analysis focused solely on cardiac surgery patients, the effective implementation of a cost-effective therapy with minimal side effects, like acupuncture, highlights its considerable value. Therefore, further research investigating the impact of acupuncture on MV in various patient conditions within an ICU setting is warranted.

To the best of our knowledge, this is the first meta-analysis investigating the specific role of acupuncture in critically ill patients under MV for various pathological conditions. In this systematic review and meta-analysis, we aim to explore the functional role, efficacy, and safety of acupuncture treatment for critically ill patients in the ICU under MV.