Effect of respiratory training intervention on rehabilitation of patients with rib fracture: a meta-analysis

Abstract

Objective

To systematically evaluate the effectiveness of respiratory training interventions in the rehabilitation of patients with rib fractures through a meta-analysis, aiming to provide robust evidence for clinical practice.

Methods

A comprehensive search was conducted in multiple databases (Pubmed, Embase, Web of Science, Cochrane Central, CNKI, Wanfang Data, and CSTJ) up to August 15, 2024, to identify relevant randomized controlled trials (RCTs). Eligible studies were those that compared RTIs plus conventional treatment with conventional treatment alone in patients with rib fractures. Study selection, data extraction, and risk of bias assessment were performed independently by two reviewers. Meta-analysis was conducted using R Studio software, with relative risk (RR) and standardized mean difference (SMD) as effect sizes, accompanied by 95% confidence intervals (95% CI).

Results

Nine RCTs involving 811 patients were included in the meta-analysis. Respiratory training interventions significantly reduced the incidence of atelectasis (RR = 0.23, 95% CI [0.13; 0.38]) and pulmonary infections (RR = 0.24, 95% CI [0.13; 0.44]), without significant heterogeneity between studies. Respiratory training interventions also shortened the length of hospital stay (SMD = -1.37, 95% CI [-1.57; -1.17]) and duration of chest tube drainage (SMD = -1.22, 95% CI [-1.43; -1.00]). Additionally, respiratory training interventions significantly improved arterial partial pressure of oxygen (PaO2) (SMD = 1.77, 95% CI [1.36; 2.18]) and arterial oxygen saturation (SaO2) (SMD = 1.92, 95% CI [1.49; 2.35]), and enhanced pulmonary function (SMD = 1.52, 95% CI [1.19; 1.84]). However, respiratory training interventions did not significantly affect the incidence of pleural effusions (RR = 1.09, 95% CI [0.49; 2.42]).

Conclusion

Respiratory training interventions significantly benefit patients with rib fractures by reducing atelectasis and pulmonary infections, shortening hospital stays and chest tube drainage times, and improving oxygenation and pulmonary function. Further high-quality studies are needed to confirm these findings and refine application strategies.

Introduction

Rib fractures refer to the breakage of rib cortical bone caused by external force and are the most common type of chest trauma [1]. They are typically caused by direct blows, traffic accidents, falls from height, or other high-energy traumas. Rib fractures can occur singly or in multiple locations; the latter often accompanies more severe chest injuries and carries a higher risk of complications [2]. Multiple rib fractures particularly increase the likelihood of chest wall instability, difficulty breathing, and damage to other intrathoracic organs, such as pulmonary contusions and hemothorax [3]. Epidemiological data show that rib fractures occur across all age groups but are especially prevalent among the elderly [4].

Rib fractures not only cause severe pain for patients but also frequently lead to restricted respiratory function, increasing the risk of complications such as atelectasis and pneumonia, thereby significantly affecting the patient's quality of life and recovery process [5]. Exploring effective supplementary treatment methods is key to improving the rehabilitation quality of patients with rib fractures. In recent years, non-pharmacological interventions have gained attention, with respiratory training interventions receiving particular focus due to their potential positive effects. Respiratory training interventions aim to improve respiratory muscle function, enhance lung capacity, and promote the clearance of respiratory tract secretions through guided exercises such as deep breathing and diaphragmatic breathing [6]. Theoretically, by alleviating respiratory pain and improving breathing patterns, these interventions can reduce the incidence of complications.

However, although preliminary studies have suggested that respiratory training interventions may benefit the rehabilitation of patients with rib fractures, the results of different studies have shown some variability. Some studies have reported positive outcomes, such as reduced hospital stays and lower re-admission risks; others have not observed significant improvements. To gain a more comprehensive understanding of the role of respiratory training interventions in the rehabilitation of rib fracture patients, this study plans to systematically review relevant literature and conduct a meta-analysis, aiming to comprehensively evaluate the impact of respiratory training interventions on the rehabilitation outcomes of patients with rib fractures, providing a scientific basis for clinical decision-making.

Materials and methods

Search strategy

A computerized search was conducted in seven databases including Pubmed, Embase, Web of Science, Cochrane Central, China National Knowledge Infrastructure (CNKI), Wanfang Data, and China Science and Technology Journal (CSTI) Database, with the search timeframe spanning from database inception to August 15, 2024. A combination of subject headings and free-text terms was used for searching, using keywords such as "respiratory training," "rib fractures," and their synonyms, tailored to the characteristics of each database. Additionally, reference lists of included studies were traced to supplement the retrieval of relevant literature. The complete search strategy is provided in Supplementary Table 1. This systematic review has been performed and written in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The protocol was registered with PROSPERO (number: CRD42025639527; URL: https://www.crd.york.ac.uk/PROSPERO/).

Inclusion and exclusion criteria

• Inclusion Criteria: 1) Studies must be randomized controlled trials (RCTs), 2) participants must be patients with rib fractures, 3) the intervention group (RT group) received conventional treatment plus respiratory training, 4) the control group received only conventional treatment (RR), including anti-infection treatment and oxygen therapy.

• Exclusion Criteria: 1) Animal experiments, 2) Conference papers, academic reports, reviews, 3) studies where full texts could not be obtained, required data could not be extracted, or combined with other rehabilitation treatments.

Literature screening and data extraction

Two reviewers independently screened the titles and abstracts of the included studies using a checklist based on eligibility criteria. Studies that did not meet the criteria were excluded. A third reviewer resolved any disagreements related to trial eligibility and assisted in the decision-making process regarding inclusion or exclusion. For studies lacking sufficient information to assess eligibility, we contacted the authors via email for clarification. Studies with insufficient information, even after contacting the authors, were excluded.

The following data were extracted from the studies: methodological design, number of participants, control group, intervention protocol, and outcome measures. Primary outcomes included the incidence of complications, length of hospital stay, duration of chest tube drainage, blood gas analysis, and pulmonary function tests. In cases of inconsistent data, a third reviewer recalculated and analyzed the data.

Risk of bias assessment

The same two reviewers used the Cochrane Risk of Bias tool to assess the risk of bias in the studies. The assessment covered the following aspects: method of random sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, completeness of outcome data, selective reporting, and other sources of bias. In cases of disagreement, a third reviewer intervened to reach consensus. Specifically, random sequence generation was considered low risk if described methods, such as computer-generated random numbers, were used. Allocation concealment was deemed low risk when procedures like sealed envelopes were used, but high risk was assigned when methods were unclear. Given the nature of the interventions, blinding of participants was often not feasible, but blinding of outcome assessors was considered low risk if reported. We also evaluated incomplete data and selective reporting, with studies showing high dropout rates or selective outcome reporting deemed at higher risk. Finally, we considered potential other biases, such as funding sources, and studies with clear conflicts of interest or methodological inconsistencies were rated as high risk.

Statistical methods

Meta-analysis was performed using R Studio software. For dichotomous variables, the relative risk (RR) was used as the effect size, while for continuous variables, the standardized mean difference (SMD) was employed, with both accompanied by 95% confidence intervals (95% CI). The I² statistic was used to assess heterogeneity. If there was no significant heterogeneity (P > 0.1, I² < 50%), a fixed-effects model was used; otherwise, a random-effects model was applied. Statistical significance was set at P < 0.05.

Results

Search results and basic characteristics of included studies

Through searches of domestic and international databases, a total of 670 relevant articles were identified. From an initial total of 670 articles, 91 duplicates were removed. 570 articles were excluded due to inconsistency in the assessment topic, incomplete data, irrelevant interventions, or methodological issues. Ultimately, 9 studies involving 811 patients were included in the meta-analysis. [6,7,8,9,10,11,12,13,14]. The literature screening flowchart is shown in Fig. 1, and the basic characteristics of the included studies are summarized in Table 1.

Fig. 1

Study inclusion flow chart

Table 1 General baseline data

Risk of bias assessment in included studies

All nine [6,7,8,9,10,11,12,13,14] included studies were RCTs. Given the nature of respiratory training interventions, it is difficult to blind participants and researchers to the allocation of interventions, and none of the studies reported blinding procedures. Furthermore, some studies did not report information on allocation concealment, which could also introduce selection bias by increasing the risk of improper assignment of participants to intervention groups. The lack of clear allocation concealment procedures in these studies raises concerns about the randomization process and its potential impact on the reliability of the results (Fig. 2).

Fig. 2

Risk of bias assessment in included studies. A: Risk of bias summary; B: Risk of bias graph

Incidence of complications

Atelectasis, pulmonary infection, and pleural effusion are common complications in patients with rib fractures. Respiratory training interventions have shown positive effects in reducing pulmonary complications in these patients.

Six studies [7, 8, 11,12,13,14] investigated the impact of respiratory training interventions on atelectasis and pulmonary infections. The results showed that respiratory training significantly reduced the incidence of atelectasis (RR = 0.23, 95% CI [0.13; 0.38]), with no statistical heterogeneity observed between studies (I² = 0%, τ² = 0, p = 0.91). Although some studies had confidence intervals crossing 1, the overall trend supports the effectiveness of respiratory training in reducing the risk of atelectasis (Fig. 3). The sensitivity analysis for atelectasis reveals that the intervention significantly reduces the incidence of this complication. Importantly, there is no observable heterogeneity, suggesting remarkable consistency among the included studies (Fig. 4).

Fig. 3

Meta analysis of risk of atelectasis

Fig. 4

Sensitive analysis of risk of atelectasis

Similarly, respiratory training effectively reduced the incidence of pulmonary infections (RR = 0.24, 95% CI [0.13; 0.44]), with no significant heterogeneity observed between studies (I² = 0%, τ² = 0.0710, p = 0.56). Despite wider confidence intervals in individual studies, the overall results indicate a positive effect of respiratory training in reducing the risk of pulmonary infections (Fig. 5). In the sensitivity analysis for pulmonary infections, the RR also remained significant when omitting individual studies. However, the slight increase in heterogeneity suggests variability in the effect sizes across studies (Fig. 6).

Fig. 5

Meta analysis of risk of pulmonary infections

Fig. 6

Sensitive analysis of risk of pulmonary infections

However, respiratory training did not significantly affect the incidence of pleural effusion (RR = 1.09, 95% CI [0.49; 2.42]), with low heterogeneity observed between studies (I² = 31%, τ² = 0.5631, p = 0.23) (Fig. 7).

Fig. 7

Meta analysis of risk of pleural effusion

Length of hospital stay

Respiratory training significantly shortened the length of hospital stay for patients with rib fractures (SMD = −1.37, 95% CI [−1.57; −1.17]), with no statistical heterogeneity observed between studies (I² = 0%, τ² = 0, p = 0.60). In the studies by Fu 2018, Wang 2024, He 2010, and Zhu 2023, the standardized mean differences (SMD) were −1.37 (95% CI [−1.57; −1.17]), −1.94 (95% CI [−0.79; −1.94]), −1.69 (95% CI [−1.16; −1.69]), and −2.10 (95% CI [−0.95; −2.10]), respectively. These results indicate that respiratory training effectively reduced hospital stay times across all studies, demonstrating a consistent and stable effect in promoting the recovery of patients with rib fractures (Fig. 8).

Fig. 8

Meta analysis of length of hospital stay

Duration of chest tube drainage

Meta-analysis showed that respiratory training significantly reduced the duration of chest tube drainage (SMD = −1.22, 95% CI [−1.43; −1.00]), with moderate heterogeneity observed between studies (I² = 71%, τ² = 0.1011, p = 0.03). This suggests that despite variations in the results of different studies, respiratory training generally reduces the duration of chest tube drainage (chest tube drainage time). This may be attributed to the promotion of lung expansion and clearance of respiratory tract secretions, thus accelerating the absorption and removal of fluid or air in the chest cavity (Fig. 9).

Fig. 9

Meta analysis of duration of chest tube drainage

Oxygenation indices

Improvements in oxygenation indices, such as PaO₂ (arterial partial pressure of oxygen) and SaO₂ (arterial oxygen saturation), were significant. Meta-analysis showed that the standardized mean difference (SMD) for PaO₂ was 1.77, with a 95% confidence interval of [1.36; 2.18], and no heterogeneity was observed between studies (I² = 0%, τ² = 0, p = 0.61). This indicates that respiratory training significantly improved arterial oxygen levels (Fig. 10). Similarly, SaO2 also showed significant improvement due to respiratory training (SMD = 1.92, 95% CI [1.49; 2.35]), though with higher heterogeneity between studies (I² = 92%, τ² = 1.2602, p < 0.01) (Fig. 11). This heterogeneity suggests that the results vary considerably between studies, possibly due to differences in intervention methods, patient populations, or baseline characteristics. However, the overall trend still indicates a positive effect of respiratory training in enhancing oxygenation status.

Fig. 10

Meta analysis of PaO₂

Fig. 11

Meta analysis of SaO₂

Pulmonary function

Respiratory training interventions also showed a certain effect in improving pulmonary function. Meta-analysis demonstrated that respiratory training significantly improved pulmonary function in patients with rib fractures (SMD = 1.52, 95% CI [1.19; 1.84]), despite substantial heterogeneity between studies (I² = 90%, τ² = 1.5414, p < 0.01) (Fig. 12). Nonetheless, the results from the random-effects model support the effectiveness of respiratory training in enhancing patients' pulmonary function.

Fig. 12

Meta analysis of FEV1/FVC

Discussion

Rib fractures are one of the most common types of chest trauma, especially prevalent among the elderly. Due to the severe pain and respiratory dysfunction associated with rib fractures, patients are prone to developing complications such as atelectasis, pulmonary infections, and pleural effusions, which not only prolong hospital stays but also significantly impact the quality of life and recovery process of patients [15, 16]. In recent years, respiratory training interventions have gained attention as a non-pharmacological treatment approach due to their potential to improve respiratory function and reduce complications [17]. However, existing research has yielded inconsistent results regarding the efficacy of respiratory training interventions. To systematically evaluate the impact of respiratory training interventions on the rehabilitation outcomes of patients with rib fractures, we conducted a meta-analysis aimed at providing clearer evidence for clinical practice.

Our study found that respiratory training interventions significantly reduced the incidence of atelectasis and pulmonary infections in patients with rib fractures. This may be related to the intervention's ability to improve respiratory mechanics and promote effective coughing, aiding in the clearance of respiratory secretions. Previous studies have indicated that shallow breathing and inadequate coughing due to pain are major causes of atelectasis and pulmonary infections in patients with rib fractures [18]. By increasing the strength and endurance of respiratory muscles, respiratory training helps restore normal breathing patterns, reducing alveolar collapse and accumulation of secretions, thereby lowering the incidence of these complications. Respiratory training can effectively improve lung volume and ventilation capacity, which is particularly important during the acute phase [19]. However, respiratory training did not significantly affect the incidence of pleural effusions, likely because the formation of pleural effusions is often associated with severe chest wall injury, pulmonary contusions, or vascular ruptures, factors that cannot be directly addressed through respiratory training [20]. Even though respiratory training improves overall respiratory function, its impact on the dynamics of intrapleural fluid may be limited, aligning with findings from some studies that failed to detect a significant effect of respiratory training on pleural effusions.

Furthermore, respiratory training interventions significantly shortened the length of hospital stay and the duration of chest tube drainage, findings with important clinical implications. Shorter hospital stays suggest an accelerated overall recovery rate, potentially due to improved respiratory efficiency resulting from respiratory training, reduced respiratory complications, enhanced lung expansion, and alveolar ventilation, thus decreasing the need for treatments related to these complications. Correspondingly, the reduction in chest tube drainage time may be related to improved lung re-expansion capabilities, better fluid absorption, and more efficient airway clearance brought about by respiratory training [21]. These results further suggest that respiratory training interventions can promote faster recovery in patients with rib fractures. This success may be indirectly related to its effects on pain management, as less pain allows patients to engage in deeper and more effective breathing and coughing, aiding in the prevention and control of pulmonary complications. Relevant studies have shown that poor pain control is closely linked to prolonged hospital stays and increased chest tube drainage times, although direct evidence is currently lacking [22].

Moreover, the significant improvement in PaO₂ and SaO₂ levels, along with the positive impact on pulmonary function, indicates that this intervention helps enhance the respiratory capacity and oxygenation status of patients with rib fractures. This may be attributed to the increased strength and coordination of respiratory muscles, leading to improved pulmonary ventilation and gas exchange. Existing research shows that respiratory training can significantly improve pulmonary function in patients with chronic respiratory diseases, an effect that is also observed in patients with rib fractures [23]. However, the heterogeneity in the improvement of oxygenation indicators and pulmonary function may reflect differences in patient characteristics, intervention methods, and measurement standards across studies. Some studies may have included patients with poorer baseline pulmonary function, making it easier to observe significant effects; whereas other studies might have had higher baseline oxygenation levels, limiting the room for improvement. Additionally, the duration and intensity of the intervention may influence the results. These factors highlight the need for future research to standardize intervention protocols and match patient characteristics.

This study has several limitations. First, because of the nature of respiratory training interventions, none of the included studies used blinding, which could introduce bias. Second, there is variability in patient characteristics and intervention protocols across studies. Although the random-effects model has addressed this variability, it may still impact the interpretation of the results. Additionally, the limited number of included studies may constrain the scope and generalizability of the analysis, making it difficult to assess publication bias using methods such as funnel plots. Due to the small sample size, subgroup analyses could not be performed, further limiting the ability to explore potential moderating factors. Moreover, the included studies predominantly focused on populations of a specific ethnic background, limiting the generalizability of the findings to more diverse populations.

Conclusion

Overall, respiratory training interventions have shown significant positive effects on the rehabilitation of patients with rib fractures, particularly in reducing the incidence of atelectasis and pulmonary infections, shortening hospital stays and chest tube drainage times, improving oxygenation levels, and enhancing pulmonary function. However, future research will require more high-quality, rigorously designed studies to further validate these findings and optimize the application strategies of respiratory training in different patient populations.