Safety and Feasibility of Fan Therapy for Dyspnea: A Scoping Review

Fan therapy is a non-pharmacological approach useful in terminally ill patients that relieves dyspnea by directing a fan to blow air on one side of the patient’s face. To date, there has been no systematic review of fan therapy for critically ill patients in the intensive care unit. This scoping review aimed to provide a comprehensive overview of fan therapy studies published to date, clarify the therapeutic intervention methods of fan therapy, evaluate its safety according to existing literature, and explore its potential use in critically ill patients. A scoping review was conducted using the Joanna Briggs Institute methodology. This scoping review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension of the scoping reviews statement. All published studies conducted on patients who received fan therapy regardless of age, disease, setting, phase, country, or follow-up duration were included. The data sources included Medical Literature Analysis and Retrieval System Online, Embase, Cochrane Central Register of Controlled Trials, and Cumulative Index to Nursing and Allied Literature databases. Of the 685 studies obtained, 15 were included, comprising patients with terminal cancer and chronic lung diseases. The most common intervention was a single five-minute intervention for dyspnea at rest. The studies on patients receiving oxygen therapy did not report adverse events or worsening of blood pressure, pulse rate, respiratory rate, or SpO2 levels. However, there are no studies in the literature on the use of fan therapy for critically ill patients. Nevertheless, previous studies suggest that fan therapy is safe.


Introduction And Background
Dyspnea is "a subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity" [1]. Dyspnea is believed to occur when there is a mismatch between motor commands from the respiratory center to the respiratory muscles and afferent information from nerves and other receptors. Dyspnea in the intensive care unit (ICU) is one of the most distressing experiences [2] and is associated with patient death [3]. It has also been suggested to play an important role in the development of ICU-related posttraumatic stress syndrome [4,5]. In a prospective observational study of critically ill patients in the ICU, the prevalence of dyspnea ranged from 34% to 63% [6][7][8]. In critically ill patients, treating dyspnea is essential to resolve the underlying cause; however, a resolution is often impossible or does not provide adequate symptom relief. In such cases, palliative interventions that target the symptom complex may effectively reduce symptom burden and distress. Fan therapy is one such intervention.
Fan therapy is a non-pharmacological approach that relieves dyspnea by directing a fan to blow air on one side of the patient's face. Figure 1 illustrates the fan therapy. However, the mechanisms underlying its effects remain unclear. It has been hypothesized that direct stimulation of the face (around the second/third trigeminal nerve branches), nasal mucosa, pharynx, or changes in facial temperature due to cooling, may affect ventilation patterns [9][10][11]. Several clinical studies have recommended fan therapy for dyspnea, and there is emerging evidence of its efficacy [12][13][14]. Therefore, fan therapy should be considered at the end of life and in critically ill patients with dyspnea in the ICU.

FIGURE 1: Fan therapy
Fan therapy consists of holding the fan at a convenient distance from the face and directing the wind to the areas innervated by the second and third branches of the trigeminal nerve.
The objective of this scoping review was to provide a comprehensive overview of published studies on fan therapy to clarify the therapeutic intervention methods of fan therapy, evaluate its safety according to existing literature, and explore its potential use in critically ill patients.

Review Protocol and registration
In accordance with a predefined protocol [15], we conducted a scoping review based on the following fivestage framework outlined by the Joanna Briggs Institute: identifying the research question; identifying relevant studies; study selection; data charting; and collating, summarizing, and reporting the results [16]. This scoping review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension of the scoping reviews statement (Appendix 1) [17]. Full details of the methodology can be found in the scoping review protocol registered as a priori in the Open Science Framework on January 9, 2023 [15].

Eligibility criteria and search strategy
Population, concept, and context frameworks were used to define the inclusion criteria [16]. All published studies conducted on patients with fan therapy, defined as the "use of an electrical fan blowing on the patient's face," [18], and studies using airflow, table fan, standing fan, and handheld fan were included in this study. Studies were included regardless of age, disease, setting (e.g., hospital, home, and institutional), phase (e.g., acute phase, chronic phase, terminal phase), country, or follow-up duration of the patients. Studies that did not fit the conceptual framework of the present review were excluded. All published randomized controlled trials (RCTs); crossover, cluster randomized, quasi-randomized, and non-randomized trials; observational studies with controls; case reports; and case series were included in the analysis. Studies in any language or country were accepted, and studies with any length of follow-up were included. Conference abstracts and review articles were excluded from the analysis.
The following databases were comprehensively searched on December 28, 2022: Medical Literature Analysis and Retrieval System Online (MEDLINE), Excerpta Medica Database (Embase), Cochrane Central Register of Controlled Trials (CENTRAL), and the Cumulative Index to Nursing and Allied Literature (CINAHL). In addition, searches were conducted using the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov to identify ongoing clinical trials. The search formulas are presented in Appendix 2. We also identified additional relevant studies by manually searching the reference lists of the included studies and relevant reviews (based on citation information from the Web of Science).

Study selection
Two reviewers (TS and YN) independently assessed the titles and abstracts, followed by an assessment of eligibility based on the full texts. If the relevant data were missing, the original authors were contacted. Disagreements between the two reviewers were resolved by discussion. If this failed, a third reviewer (KS) acted as an arbiter.

Data extraction and synthesis
Data extraction was conducted by a researcher (TS) using a standard data extraction form, including disease, setting, study type, number of participants, fan therapy intervention, control, outcomes, changes in respiratory rate, SpO 2 levels, pulse rate, blood pressure before and after fan therapy, adverse events, and feasibility. Another researcher (YN) verified the data extraction process. Where necessary, the authors of the reviewed publications were contacted. We organized the extracted data described above for qualitative synthesis.

Discussion
To our knowledge, this is the first scoping review of fan therapy interventions and their safety and feasibility, especially in critically ill patients. We included 15 studies involving 505 participants and clarified that the available evidence for fan therapy is based primarily on patients with terminal-phase cancer, chronic-phase COPD, and cardiac disease. Based on the studies identified in our review, fan therapy appears to be safe when administered at rest and during exercise, with no adverse events reported. However, this scoping review found no evidence of fan therapy in critically ill patients.
We found that fan therapy mainly focused on the outcome of dyspnea relief in patients with terminal cancer, COPD, and cardiac disease. These interventions have three main characteristics. The first was a short-term intervention with a five-minute intervention period for dyspnea at rest, which was the most common intervention [12,13,18,[20][21][22]28,30]. The second was a short-term intervention for dyspnea on exertion during exercise, such as a simple step test on an exercise step or ergometer [25][26][27]. This intervention was mainly performed in patients with respiratory diseases, such as COPD and ILD, and investigated improvement in exercise capacity as an outcome. Third, only three studies involved long-term interventions of 14 days or more using fan therapy [19,23,24].
Long-term interventions also have specific problems with reports of withdrawals due to changes in medical conditions [19]. The assessment tools used were the NRS [12,13,21,22,25,28], VAS [12,18,20], and mBorg [27,30] for short-duration interventions to evaluate safety in terms of changes in dyspnea intensity before and after a single intervention and physiological outcomes. By contrast, long-term interventions use dyspnea-12 to assess the quality of dyspnea in the physical and affective domains and secondary outcomes associated with improvement in dyspnea [23], such as health-related quality of life. Dyspnea assessment tools are broadly classified according to whether they evaluate the quantity or quality of dyspnea or its impact on life (quality of life-related). Those that can measure the expected outcome according to the purpose should be used [33][34][35]. For example, NRS, VAS, and respiratory distress observation scale (RDOS) should be used to evaluate the effect size of fan therapy. Likewise, to evaluate the quality of the effect, dyspnea-12 should be used. The most commonly used devices were handheld fans [12,18,19,[23][24][25]28]. In long-term interventions, handheld fans are often used, and in the intervention plan, the patients are instructed to use them when their symptoms worsen. Long-term interventions require patients to come to terms with their illnesses. Handheld fans can be used indoors and outdoors. Indoors, they can be easily used to aid activities of daily living, such as washing and dressing, by relieving dyspnea during movement [36,37]. Standing fans [20][21][22] and table fans [13,29] are frequently selected in palliative care wards. We believe that the researchers selected a standalone fan because it becomes difficult for the patient to keep a handheld fan by themselves owing to the progression of their medical condition and other factors. Therefore, the device selected for use in fan therapy should be based on the patient's medical condition and intended use.
Fan therapy has been suggested to relieve dyspnea through trigeminal activation of brain regions related to dyspnea, such as the insular cortex, anterior cingulate cortex, and amygdala, without improvement in breathing patterns or other physiological outcomes [38]. Based on the studies included in this review, no adverse events were reported, with no worsening of SpO 2 , respiratory rate, pulse rate, or blood pressure before or after fan therapy, suggesting that the use of fan therapy was safe. However, the results should be interpreted with caution, as only eight studies reported no adverse events. The possibility that some adverse events may have occurred in the unreported studies cannot be ruled out. Possible adverse events may include dry eyes and airways, although the likelihood and duration of these potential side effects are yet to be determined. Furthermore, it has been mentioned that fan therapy can alleviate dyspnea by "fooling the brain" and by "making" patients believe that their breathing is working better than it is, making it possible to miss dangerous signs in patients [39]. Therefore, in the future, rather than focusing only on the efficacy of fan therapy, the adverse events and physiological outcomes should be investigated to verify its safety.
The available evidence for fan therapy included studies on patients receiving oxygen therapy during the terminal phase, which confirmed its safety [20][21][22][23]26]. In the terminal phase, patients may be unable to maneuver themselves; thus, a standing fan or table fan could be chosen. Critically ill patients may also be unable to operate the fan independently due to sedation or ICU-acquired weakness. Therefore, even for critical care patients who cannot operate a fan on their own, fan therapy might be easily provided by selecting a standalone fan that can be operated by a healthcare professional when the patient requests to adjust the speed and direction of the fan. Electric fans are inexpensive and readily available, and handheld fans or table fans can be selected to minimize the space required for installation. Fan therapy does not require specialized knowledge to operate the fan and can be easily implemented by simply pressing the switch on the fan and blowing the wind onto the face. Currently, there are two ongoing studies recruiting participants admitted to the ICU [31,32]. However, further investigation into the safety of the intervention in this setting is warranted. It has been reported that patients with dyspnea have a slower weaning process and undergo prolonged ventilation [8]. Given this, the use of fan therapy for the treatment of dyspnea might improve post-intensive care syndrome (PICS) in patients by facilitating weaning and shortening the duration of ventilation.

Limitations
The present review has several strengths and limitations. The results are based on the evidence currently available from a comprehensive literature search. In addition, we employed a rigorous methodology followed by a written protocol developed a priori. The study limitations are as follows: the findings in this review are based on the analysis of a single intervention that was performed for a short duration (i.e., a few minutes). The studies included both chronic and terminal phase patients, but all the studies had small sample sizes. In addition, only two studies on long-term interventions differed in terms of duration and type of interventions, and there may be many unknown factors regarding safety and feasibility. Thus, the safety aspect of fan therapy cannot be generalized. However, this scoping review is also the first to identify a lack of evidence for fan therapy in critical care patients. In addition, this scoping review was not designed to assess methodological quality, and conclusions regarding the quality of the included studies should be interpreted with caution.

Conclusions
In conclusion, previous studies on fan therapy have mainly focused on patients with terminal or chronic cancer and pulmonary and cardiac diseases. Fan therapy was performed at rest and during exercise using a handheld or standing fan, and changes in dyspnea and exercise capacity were investigated. In the studies included in our scoping review, there were no reports of worsening physiologic outcomes or adverse events.
Although there are ongoing studies on using fan therapy for patients in a critical care setting, further studies are required to determine the safety of fan therapy in critically ill patients. Describe the methods of charting data from the included sources of evidence (e.g., calibrated forms or forms that have been tested by the team before their use, and whether data charting was done independently or in duplicate) and any processes for obtaining and confirming data from investigators. Figure  * Where sources of evidence (see second footnote) are compiled from, such as bibliographic databases, social media platforms, and Web sites. † A more inclusive/heterogeneous term used to account for the different types of evidence or data sources (e.g., quantitative and/or qualitative research, expert opinion, and policy documents) that may be eligible in a scoping review as opposed to only studies. This is not to be confused with information sources (see first footnote). ‡ The frameworks by Arksey and O'Malley (6) and Levac and colleagues (7) and the JBI guidance (4,5) refer to the process of data extraction in a scoping review as data charting. § The process of systematically examining research evidence to assess its validity, results, and relevance before using it to inform a decision. This term is used for items 12 and 19 instead of "risk of bias" (which is more applicable to systematic reviews of interventions) to include and acknowledge the various sources of evidence that may be used in a scoping review (e.g., quantitative and/or qualitative research, expert opinion, and policy document). ) OR (breathless:ti,ab)) OR (breathlessness:ti,ab)) OR ("labored breathing":ti,ab)) OR ("shortness of breath":ti,ab)) OR ("breath shortness":ti,ab)) OR ("inspiratory retraction":ti,ab)) OR ("breathing difficulty":ti,ab)) OR ((dyspnoea:ti,ab) NOT (dyspnea:ti,ab))) AND (("air flow":ti,ab) OR (fan:ti,ab)) CINAHL S1 MH (dyspnea) S9 TI (inspiratory retraction) OR AB (inspiratory retraction) S10 TI (breathing difficulty) OR AB (breathing difficulty) S11 S3 NOT S2 S12 S1 OR S2 OR S4 OR S5 OR S6 OR S7 OR S8 OR S9 OR S10 OR S11 S13 TI (air flow) OR AB (air flow) S14 TI (fan) OR AB (fan) S15 S13 OR S14 S16 S12 AND S15

Appendices
(((((((((((MH dyspnea+)) OR ((TI dyspnea OR AB dyspnea))) OR ((TI breathless OR AB breathless))) OR ((TI breathlessness OR AB breathlessness))) OR ((TI "labored breathing" OR AB "labored breathing"))) OR ((TI "shortness of breath" OR AB "shortness of breath"))) OR ((TI "breath shortness" OR AB "breath shortness"))) OR ((TI "inspiratory retraction" OR AB "inspiratory retraction"))) OR ((TI "breathing difficulty" OR AB "breathing difficulty"))) OR (((TI dyspnoea OR AB dyspnoea)) NOT ((TI dyspnea OR AB dyspnea)))) AND (((TI "air flow" OR AB "air flow")) OR ((TI fan OR AB fan)))   Grant-in-Aid for Research Activity Start-up. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.