Evaluation of Pulmonary Function in Long-Term Follow-Up After Laparoscopic Sleeve Gastrectomy

doi:10.21203/rs.3.rs-4857619/v1

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Evaluation of Pulmonary Function in Long-Term Follow-Up After Laparoscopic Sleeve Gastrectomy

https://doi.org/10.21203/rs.3.rs-4857619/v1

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Aim: Obesity is one of the most important health problems in the world. It affects all systems, especially the respiratory and cardiovascular systems. Laparoscopic bariatric surgery is an effective method in the treatment of obesity and can improve respiratory functions. We aimed to evaluate the effects of surgery on pulmonary function in patients with obesity.

Methods: A retrospective analysis was conducted on a group of patients who underwent bariatric surgery. Pre- and postoperative pulmonary function tests were compared. Patients were stratified based on smoking status and presence of comorbidities.

Results: The study included 51 patients (82.4% female) with a mean age of 51.90 ± 11.57 years. Significant weight loss and reductions in BMI were observed postoperatively. Pulmonary function tests demonstrated significant improvements in FEV1, FEV1%, PEF, and MEF25-75 after surgery. These improvements were consistent across different subgroups, including smokers, non-smokers, patients with and without comorbidities.

Conclusion: Bariatric surgery is associated with significant improvements in pulmonary function in obese patients, regardless of smoking status or comorbidities.

Bariatric surgery

obesity

pulmonary function

FEV1

PEF

MEF25-75

Obesity is a global public health problem today and can lead to many diseases such as diabetes, heart disease, and cancer [1]. Obesity surgery is the most effective treatment method for weight loss in patients with morbid obesity. In 2015, 604 million adults worldwide were obese, and the rate was higher in women than in men [2]. Obesity prevalence was found to be 41% in women, 20.5% in men, and 30.3% in the overall population [3]. As a chronic disease with increasing global prevalence, obesity is expected to increase to 51% worldwide by 2030 [4].

Obesity has far-reaching systemic effects. Long-term consequences include increased risks of cardiovascular disease, diabetes mellitus, and various cancers. The respiratory system is significantly impacted by obesity. Obesity is a well-established risk factor for obstructive sleep apnea, leading to increased fat deposition in the pharyngeal airways [5]. Moreover, obese individuals exhibit a higher prevalence, severity, and hospitalization rate for asthma [6]. Obesity hypoventilation syndrome, a respiratory disorder characterized by inadequate ventilation, is another common complication in obese individuals, affecting 8–20% of this population [7]

While dietary and pharmacological interventions are commonly employed in obesity management, suboptimal outcomes are frequent. Bariatric surgery has emerged as the gold standard for long-term weight management in severely obese individuals, inducing significant and sustained weight loss [8]. Post-bariatric surgery, patients often experience remission of obesity-related comorbidities such as type 2 diabetes, hypertension, and cardiovascular disease. Additionally, improvements in respiratory conditions, including obstructive sleep apnea, are commonly reported [9]

Although there have been numerous studies investigating the effects of bariatric surgery on respiration in the early period, long-term follow-up studies are very limited. The aim of our study is to investigate the effect of bariatric surgery on respiratory function ten years after surgery in patients who were evaluated preoperatively in our clinic for bariatric surgery.

This cross-sectional study aimed to assess the pre-operative and long-term (10 years) pulmonary function in patients who underwent laparoscopic bariatric surgery at Kahramanmaraş Sütçü İmam University between 2009 and 2015. Ethical approval for this study was obtained from the Non-Interventional Clinical Research Ethics Committee of Kahramanmaraş Sütçü İmam University on March 14, 2024 (approval number 58).

The long-term impact of bariatric surgery on respiratory function tests (SFT) was investigated in participants who fulfilled the inclusion criteria, agreed to the study conditions, and provided informed consent. Specifically, the study examined the effects of surgery on respiratory function parameters such as FEV1, FVC, FEV1/FVC ratio, peak expiratory flow (PEF), and mean flow between 25–75% of forced vital capacity (MEF25-75). These parameters were extracted from the participants' medical records, which also included data on body mass index, age, comorbidities, and smoking history.

Statistical Analysis

ata were analyzed using SPSS version 20.0. The normality of the data was assessed using visual methods (histograms and probability plots) and analytical tests (Kolmogorov-Smirnov and Shapiro-Wilk tests). Descriptive statistics were presented as mean ± standard deviation for continuous variables with normal distribution, and as median, minimum, and maximum for those without. For categorical variables, frequency (n) and percentage (%) were reported.

For continuous data collected from repeated measurements of the same subjects, paired t-tests were employed when data followed a normal distribution. For non-normal data, the Wilcoxon signed-rank test was used. The Spearman correlation test was conducted to assess the relationship between variables. The correlation table below summarizes the relationship status. Statistical significance was set at p < 0.05.

According to the power analysis, the effect size was found to be 0.454 based on the values of obese patients who underwent obesity surgery in the reference study (Campos et al., 2018). Considering an alpha of 0.05 for a type I error, a beta of 0.20 for a type II error, a power of 0.80, and an effect size of 0.454, the calculation indicated that n:41 patients were planned to be included in the study

The descriptive and sociodemographic characteristics of the participants are presented in Table 1. The mean age of the patients was 51.90 ± 11.57 years (median: 56.0, range: 27.0–72.0). Nine patients (17.6%) were male, and 42 (82.4%) were female. Upon further examination, it was found that 13 (26.5%) of the participants were smokers, and 23 (45.1%) had comorbidities.

Table 1

Sociodemographic and Spirometry Characteristics
Characteristic	Pre-Operative	Post-Operative	p
Age	41.43 ± 11.31	51.90 ± 11.57	< 0.001**
Height	-	163.41 ± 7.36	-
Weight	126.62 ± 16.97	100.78 ± 16.56	< 0.001*
BMI	47.53 ± 6.95	37.75 ± 6.02	< 0.001*
FEV1 (L)	2.65 ± 0.69	2.76 ± 0.67	0.044**
FEV1 (%)	92.07 ± 15.31	97.98 ± 14.45	0.001*
FVC (L)	3.31 ± 0.80	3.40 ± 0.77	0.116*
FEV1/FVC	80.94 ± 7.40	81.22 ± 6.37	0.781*
PEF	74.01 ± 18.12	91.53 ± 24.16	< 0.001**
MEF25-75	77.17 ± 22.07	108.57 ± 28.11	< 0.001**
Paired T-test, *Wilcoxon test
Abbreviations: BMI: Body Mass Index, FEV1: Forced Expired Volume in 1 Second, FVC: Forced Vital Capacity, PEF:Peak Expiratory Flow, MEF25-75:Maximum Expiratory Flow 25–75% of FVC

Patients had a mean pre-operative weight of 126.62 ± 16.97 kg, which significantly decreased to 100.78 ± 16.56 kg following surgery (p < 0.001) (Table 1). Likewise, mean pre-operative BMI was 47.53 ± 6.95 and significantly decreased to 37.75 ± 6.02 post-operatively (p < 0.001) (Table 1).

The FEV1 (in liters) significantly increased from 2.65 ± 0.69 before surgery to 2.76 ± 0.67 after surgery (p < 0.044). The FEV1 (% predicted) value also significantly increased from 92.07 ± 15.31 before surgery to 97.98 ± 14.45 after surgery (p < 0.001) (Table 1). Although not statistically significant, FVC (in liters) increased from 3.31 ± 0.80 to 3.40 ± 0.77. The FEV1/FVC ratio did not change significantly, remaining at 80.94 ± 7.40 before surgery and 81.22 ± 6.37 after surgery. PEF, which was 74.01 ± 18.12 before surgery, significantly increased to 91.53 ± 24.16 after surgery (p < 0.001). MEF25-75, which was 77.17 ± 22.07 before surgery, also significantly increased to 108.57 ± 28.11 after surgery (p < 0.001) (Table 1).

In smokers, FEV1 (L) increased significantly from 2.65 ± 0.69 to 2.76 ± 0.67 (p < 0.044), FEV1 (%) also increased significantly from 95.07 ± 11.84 to 99.69 ± 13.29 (p = 0.016). After surgery, FVC (L) in smoking patients increased from 3.25 ± 0.38 to 3.37 ± 0.46, but there was no significant change in FEV1/FVC. The PEF value in smokers increased from 77.92 ± 18.31 before surgery to 88.85 ± 18.64 after surgery. Similarly, the MEF25-75 value, which was 73.61 ± 15.06 before surgery, increased significantly to 102.54 ± 23.91 (p < 0.001) (Table 2).

Table 2

RFT Characteristics According to Surgery Status in Smokers
	Smokers Pre-Surgery	Smokers Post-Surgery	p
FEV1 (lt)	2.61 ± 0.38	2.69 ± 0.39	0.124**
FEV1 (%)	95.07 ± 11.84	99.69 ± 13.29	0.016*
FVC (lt)	3.25 ± 0.38	3.37 ± 0.46	0.178*
FEV1/FVC	80.30 ± 5.29	79.85 ± 4.58	0.717*
PEF	77.92 ± 18.31	88.85 ± 18.64	< 0.069**
MEF25-75	73.61 ± 15.06	102.54 ± 23.91	0.001**
Paired T-test, *Wilcoxon test
Abbreviations: FEV1: Forced Expired Volume in 1 Second, FVC: Forced Vital Capacity, PEF:Peak Expiratory Flow, MEF25-75:Maximum Expiratory Flow 25–75% of FVC

In non-smokers, FEV1 (%) significantly increased from 91.05 ± 16.35 pre-operatively to 97.39 ± 14.95 post-operatively (p < 0.005). Pre-operative FVC(It) value of 3.33 ± 0.91 increased to 3.40 ± 0.85. PEF significantly increased from 72.69 ± 18.11 to 92.44 ± 25.94 (p < 0.001). MEF25-75 also significantly increased from 78.39 ± 24.06 to 110.64 ± 29.41 (p < 0.001) (Table 3).

Table 3

RFT Characteristics According to Surgery Status in Nonsmokers
Feature	Nonsmokers Pre-Surgery	Nonsmokers Post-Surgery	p
FEV1 (L)	2.67 ± 0.78	2.78 ± 0.74	0.105**
FEV1 (%)	91.05 ± 16.35	97.39 ± 14.95	0.005*
FVC (L)	3.33 ± 0.91	3.40 ± 0.85	0.265*
FEV1/FVC	81.16 ± 8.05	81.70 ± 6.86	0.683*
PEF	72.69 ± 18.11	92.44 ± 25.94	< 0.001**
MEF25-75	78.39 ± 24.06	110.64 ± 29.41	< 0.001**
Abbreviations: FEV1: Forced Expired Volume in 1 Second, FVC: Forced Vital Capacity, PEF:Peak Expiratory Flow, MEF25-75:Maximum Expiratory Flow 25–75% of FVC

In patients with concomitant diseases, pre-operative FEV1 (L) increased from 2.39 ± 0.63 to 2.44 ± 0.49, and FEV1 (%) increased from 88.78 ± 15.04 to 92.95 ± 12.86. Pre-operative FVC (L) increased from 3.02 ± 0.66 to 3.03 ± 0.55. There was no significant change in FEV1/FVC. Pre-operative PEF, which was 69.34 ± 19.94, significantly increased to 93.86 ± 31.45 (p < 0.001). Pre-operative MEF25-75, which was 72.91 ± 18.67, significantly increased to 102.86 ± 26.56 (p < 0.001) (Table 4).

Table 4

RFT Characteristics According to Surgical Status in Patients with Comorbidities
	Pre-Surgery in Patients with Comorbidities	Post-Surgery in Patients with Comorbidities	p
FEV1 (lt)	2.39 ± 0.63	2.44 ± 0.49	0.784**
FEV1 (%)	88.78 ± 15.04	92.95 ± 12.86	0.184*
FVC (lt)	3.02 ± 0.66	3.03 ± 0.55	0.973*
FEV1/FVC	80.52 ± 6.91	80.28 ± 7.71	0.906*
PEF	69.34 ± 19.94	93.86 ± 31.45	0.001**
MEF25-75	72.91 ± 18.67	102.86 ± 26.56	< 0.001**
Abbreviations: FEV1: Forced Expired Volume in 1 Second, FVC: Forced Vital Capacity, PEF:Peak Expiratory Flow, MEF25-75:Maximum Expiratory Flow 25–75% of FVC

In patients without concomitant diseases, FEV1 (L) increased significantly from 2.87 ± 0.69 to 3.03 ± 0.68 before and after surgery, respectively (p < 0.001). FEV1 (%) increased significantly from 94.78 ± 15.28 to 102.11 ± 14.59 (p < 0.001). FVC (L) increased from 3.54 ± 0.84 to 3.70 ± 0.81. There was no significant change in FEV1/FVC. PEF increased significantly from 77.85 ± 15.81 to 89.61 ± 16.35 after surgery (p < 0.001). MEF25-75 increased significantly from 80.67 ± 24.29 to 113.27 ± 28.95 after surgery (p < 0.001) (Table 5).

Table 5

RFT Characteristics According to Surgery Status in Patients Without Comorbidity
Feature	Pre-surgery in patients without comorbidity	Post-surgery in patients without comorbidity	p
FEV1 (lt)	2.87 ± 0.69	3.03 ± 0.68	0.002**
FEV1 (%)	94.78 ± 15.28	102.11 ± 14.59	< 0.001*
FVC (lt)	3.54 ± 0.84	3.70 ± 0.81	0.025*
FEV1/FVC	81.29 ± 7.89	82.01 ± 5.05	0.466*
PEF	77.85 ± 15.81	89.61 ± 16.35	0.001**
MEF25-75	80.67 ± 24.29	113.27 ± 28.95	< 0.001**
Abbreviations: FEV1: Forced Expired Volume in 1 Second, FVC: Forced Vital Capacity, PEF:Peak Expiratory Flow, MEF25-75:Maximum Expiratory Flow 25–75% of FVC

Of the patients in our study, 17.6% were male and 82.4% were female. A 2015 study reported a higher prevalence of obesity among women compared to men. The predominance of women among patients undergoing laparoscopic gastric bypass surgery for obesity aligns with the higher prevalence of morbid obesity in women [2]

A bariatric surgery study with a follow-up period of over 10 years revealed an average weight loss of 30.1 kg [10]. Participants demonstrated a significant decrease in BMI from 47.53 ± 6.95 pre-operatively to 37.75 ± 6.02 ten years post-operatively. Additionally, there was a significant reduction in weight from 126.62 ± 16.97 kg to 100.78 ± 16.56 kg. Similarly our patients lose weight from 126.62 ± 16.97 to 100.78 ± 16.56.

Patients with morbid obesity experience both restrictive and obstructive breathing impairments. Fat deposition in the thoracic and abdominal cavities reduces lung compliance, resulting in restrictive lung disease [11]. Concurrently, upper airway obstruction caused by adipose tissue accumulation contributes to obstructive lung disease. The increased soft tissue mass associated with obesity exerts pressure on the chest wall and elevates pulmonary blood flow. Both forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) are diminished in obese individuals, although the FEV1/FVC ratio typically remains unaffected. Obese patients exhibit tachypnea and reduced tidal volumes. Airway resistance is elevated in this population [12].

Our research has shown that obesity surgery significantly improves all SFT parameters. Obesity induces various physiological alterations that compromise lung capacity and function. By facilitating weight loss and reversing these adverse changes, obesity surgery enhances pulmonary function.

MEF25-75 is employed to diagnose small airway obstruction. PEF offers insights into large airway obstruction [13]. The quantity of adipose tissue within the airways is correlated with BMI in humans. This indicates to us that the presence of adipose tissue within the airway wall modifies airway conduct [14]. Research has demonstrated a higher prevalence of asthma in obese individuals compared to non-obese individuals [15].

Weight gain causes an increase in airway resistance due to the mechanical effect of obesity on the respiratory system. Numerous studies conducted in Europe and America have shown that airway resistance is higher in obese adults compared to lean adults [12]. Beyond its mechanical impacts, obesity-induced inflammation is recognized as a contributing factor to respiratory diseases. Adipose tissue is an active endocrine organ that secretes various hormones and cytokines and is closely related to inflammation. Many studies have shown that obesity is a risk factor for chronic respiratory diseases, especially asthma and chronic obstructive pulmonary disease [16]. Weight reduction in obese individuals can reverse these findings, thereby improving respiratory findings in patients. In one study, 24 patients were evaluated six months after bariatric surgery. Significant increases were observed in FEV1 and FVC values, while no significant change was observed in the FEV1/FVC ratio. In another study of 68 patients who underwent bariatric surgery and were compared again one year later in terms of respiratory function, significant increases were observed in FEV1, FVC, PEF, and MEF25-75 values [17].

A key finding of our study is that laparoscopic bariatric surgery led to a significant improvement in patients' pulmonary function, as evidenced by marked increases in FEV1, FEV1%, PEF, and MEF25-75 (p < 0.05) (Table 1). These results suggest that laparoscopic bariatric surgery can substantially enhance airflow and lung capacity in individuals with obesity. While FEV1/FVC showed a non-significant trend towards improvement, FVC and FVC% increased without reaching statistical significance (p > 0.05) (Table 2). The significant long-term increase in FEV1 following weight loss may be attributed to the attenuation of chronic inflammatory processes associated with obesity.

Cigarette smoking induces widespread alterations in lung tissue and reduces respiratory volume [18]. A noteworthy finding of our study is that bariatric laparoscopic surgery yields superior improvements in all SFT parameters among non-smokers relative to smokers. This indicates that laparoscopic bariatric surgery has the potential to enhance respiratory function, even in individuals who smoke.

A limitation of our study was the small number of cases. Furthermore, we lacked data on patients' waist circumference or body fat percentage. There are no existing long-term follow-up studies of LSG performed in the Turkish obese population. Our study fills this gap in the literature. In conclusion, this study suggests that laparoscopic bariatric surgery can significantly improve respiratory function in obese patients over the long term. Laparoscopic bariatric surgery could be a viable treatment option for improving respiratory function in obese patients.

Bariatric surgery is an effective method for treating morbid obesity and also reduces the risk of chest diseases in the long term. Surgical treatment of obesity has a positive impact on respiratory function. Therefore, bariatric surgery can be considered as a treatment option to reduce the risk of chest diseases in patients with morbid obesity

Financial disclosure

The authors declare that they have not received any financial support for this work.

Conflict of Interest

There is no conflict of interest.

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all individual participants included in the study.

Conflict of Interest

There is no conflict of interest.

Author Contribution

Author ContributionsPlanning, design: HS, MSMaterials, methods, and data collection: HS, MS, NA, EB, BAAnalysis and interpretation: HS, CK, BA, HKWriting and critical review: HS, MS, NA

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You are reading this latest preprint version

Evaluation of Pulmonary Function in Long-Term Follow-Up After Laparoscopic Sleeve Gastrectomy

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Version 1

Abstract

INTRODUCTION

MATERIAL AND METHOD

Statistical Analysis

FINDINGS

DISCUSSION

CONCLUSION

Declarations

Conflict of Interest

Author Contribution

References

Additional Declarations

Status:

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