Risk factors for postoperative respiratory complications following retroperitoneal laparoscopic adrenalectomy: a cohort study

Introduction

Laparoscopic adrenalectomy (LA) is widely regarded as the standard surgical technique for treating most benign and selected malignant adrenal lesions due to its minimally invasive nature and favorable postoperative outcomes (1,2). Compared to open adrenalectomy, LA offers significant advantages, including reduced intraoperative blood loss, fewer postoperative complications, faster recovery times, and less postoperative pain (3). Additionally, LA is associated with a lower incidence of systemic complications such as ischemic heart disease, cardiovascular diseases (CVD), wound infections, and urinary tract infections, further highlighting its safety and efficacy (4). These benefits make LA the preferred method for treating adrenal lesions, particularly in patients with complex comorbidities.

The adrenal glands are located in the retroperitoneal space above the kidneys, surrounded by perirenal fat and encased by Gerota’s fascia, presenting challenges in exposure of adrenal glands during adrenalectomy (5). Several minimally invasive techniques have been developed for LA, with retroperitoneal and transperitoneal approaches being the most commonly utilized to access the adrenal glands (6). Retroperitoneal laparoscopic adrenalectomy (RLA), when compared to transperitoneal laparoscopic adrenalectomy (TLA), generally results in a quicker recovery and shorter hospital stays, as it avoids interference with the intestines and other associated complications (7). However, like all surgical procedures, RLA is not without risks, and postoperative complications remain a concern. Reports show that the complication rate for LA ranges from 1.7% to 30.7%, with various factors such as the patient’s sex, surgical indication, approach, and comorbidities identified as risk factors for perioperative complications and extended hospital stays (8,9).

Postoperative respiratory complications, while less common than other complications, can significantly affect patient outcomes and increase hospital stays. The causes of these complications are often multifactorial and may be influenced by patient-specific characteristics (10,11). However, limited data are available regarding the specific risk factors for respiratory complications following RLA. Identifying these factors is crucial for optimizing perioperative management and reducing complication rates. This knowledge gap underscores the importance of further investigation into respiratory complications in the setting of RLA to optimize perioperative management and reducing complication rates.

This study retrospectively analyzes clinical data from a substantial cohort of patients who underwent RLA to identify the risk factors associated with postoperative respiratory complications. The findings of this study contribute to the current understanding of complications following RLA and provide insights for clinical decision-making, ultimately improving patient outcomes in this surgical setting. We present this article in accordance with the STROBE reporting checklist (available at https://gs.amegroups.com/article/view/10.21037/gs-24-433/rc).

Methods

Study design and data collection

A retrospective study was conducted on the medical records of 569 consecutive patients who underwent RLA for adrenal disorders in the Department of Urology at Beijing Anzhen Hospital, Capital Medical University, between January 2012 and December 2021. Data extracted for analysis included patient demographics (age, sex), operative details (operative time from trocar insertion to abdominal closure, estimated intraoperative blood loss), American Society of Anesthesiologists (ASA) score, body mass index (BMI), surgeon experience (categorized as the first 30 cases per surgeon), tumor laterality (left or right), type of adrenalectomy (partial or total), lesion size (measured by maximum diameter in centimeters), perioperative complications (graded using the Clavien-Dindo classification for Grades II–V), and preoperative comorbidities (including hypertension, diabetes, CVD, and respiratory disease).

Inclusion criteria for the study were: (I) patients diagnosed with adrenal lesions, with postoperative pathological confirmation of adrenal adenoma or hyperplasia; and (II) those who underwent RLA. Exclusion criteria included: (I) patients who underwent robot-assisted RLA; (II) those who received TLA; (III) patients with other pathological types of adrenal lesions, such as malignant adrenal tumors, cysts, or myelolipomas; and (IV) patients with a history of ipsilateral retroperitoneal surgery. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). This study protocol was approved by the ethics committee of Beijing Anzhen Hospital (No. 2024249X). Individual consent for this retrospective analysis was waived.

Outcome definition

The primary outcome was the occurrence of postoperative respiratory complications, defined as those arising from the day of surgery until the day of hospital discharge. Complications were classified using the Clavien-Dindo system (12), and only complications graded 2 or higher were included in this analysis.

Statistical analysis

Continuous variables with a normal distribution were expressed as mean ± standard deviation, and differences between the respiratory complication group and the non-respiratory complication group were compared using Student’s t-test. For non-normally distributed data, results were presented as median with interquartile range (IQR), and the Wilcoxon rank-sum test was applied for comparisons. Categorical variables were compared between groups using the Chi-squared test or Fisher’s exact test, as appropriate. Univariate and multivariate logistic regression models were employed to analyze the risk factors associated with postoperative respiratory complications following RLA. Variables with a P value <0.2 in the univariate analysis were included in the multivariate analysis. Receiver operating characteristic (ROC) curves were plotted to assess the predictive value of the identified risk factors for respiratory complications post-RLA. Statistical analyses were performed using Stata 18.0 and R Studio 4.2 software for Mac, with a P value <0.05 considered statistically significant.

Results

Clinical data of patients

A total of 569 patients who underwent unilateral RLA were included in the study, comprising 294 males (51.7%) and 275 females (48.3%). Of these, 334 (58.7%) underwent left-sided RLA, while 235 (41.3%) underwent right-sided RLA. The mean age of the patients was 52.3±11.5 years. Among them, 529 patients (93.0%) had hypertension, 142 patients (25.0%) had diabetes, 33 patients (5.8%) had preoperative respiratory disease comorbidity, and 116 patients (20.4%) had CVD. Partial adrenalectomy was performed in 423 cases (74.3%), while total adrenalectomy was performed in 146 cases (25.7%). The postoperative pathological findings included adrenocortical adenoma in 433 patients (76.1%) and adrenocortical hyperplasia in 136 patients (23.9%).

A total of 30 patients (5.27%) developed Clavien-Dindo grade II or higher postoperative respiratory complications, including 16 cases of respiratory infections (2.8%), 9 cases of postoperative cough requiring antitussive treatment (1.6%), 3 cases of bronchial asthma (0.5%), and 2 cases of respiratory failure (0.4%). Significant differences were observed between the respiratory complication group and the non-respiratory complication group in terms of tumor laterality and preoperative respiratory disease comorbidity. However, no statistically significant differences were found between the two groups regarding sex, age, type of resection, lesion size, BMI, surgeon experience, pathological type, ASA, operative time, estimated blood loss or other comorbidities (P>0.05). See Table 1 for details.

Univariate and multivariable logistic regression analysis

Univariate logistic regression was initially applied to identify the risk factors for postoperative respiratory complications following RLA. The results indicated that operative time [odds ratio (OR) =1.007, P=0.043], right-sided RLA (OR =3.544, P=0.002), and preoperative respiratory disease (OR =6.005, P<0.001) were significantly associated with the occurrence of postoperative respiratory complications after RLA. Other factors, including sex, age, type of resection, lesion size, BMI, surgeon experience, pathological type, ASA score, and other comorbidities, were not significantly associated with postoperative respiratory complications (all P>0.05) (Table 2).

Subsequently, multivariate logistic regression analysis demonstrated that preoperative respiratory disease comorbidity (OR =7.243, P<0.001) and right-sided RLA (OR =4.227, P=0.001) were independent risk factors for developing respiratory complications after RLA (Table 3).

ROC curve analysis

Using operative time, right-sided RLA, and preoperative respiratory disease as predictive factors, a ROC curve was generated to evaluate the predictive accuracy of these variables for postoperative respiratory complications. The area under the curve (AUC) was determined to be 0.752 (95% CI: 0.657–0.848), indicating a moderate discriminatory capability of the model (Figure 1). This AUC suggests that the identified variables can effectively differentiate between patients who are at risk of developing respiratory complications and those who are not. The ROC curve analysis offers valuable insights into the sensitivity and specificity of these risk factors, which can enhance clinical decision-making and improve preoperative risk stratification.

Figure 1 ROC curve for predicting postoperative respiratory complications following RLA. The predictive model incorporates operative time, right-sided RLA, and preoperative respiratory disease as variables. The AUC is 0.752 (95% CI: 0.657–0.848), indicating moderate discriminatory ability in differentiating patients at risk for developing postoperative respiratory complications. ROC, receiver operating characteristic; RLA, retroperitoneal laparoscopic adrenalectomy; AUC, area under the curve; CI, confidence interval.

Discussion

This study aimed to identify risk factors associated with postoperative respiratory complications following RLA. Our findings indicated that operative time, right-sided RLA, and preoperative respiratory disease significantly elevated the likelihood of developing postoperative respiratory complications. Notably, right-sided RLA and preexisting respiratory disease were identified as independent risk factors, underscoring their critical roles in perioperative risk assessment.

The relationship between operative time and postoperative complications has been well established across various surgical procedures (13,14). In our univariate analysis, we found that with every additional minute of operative time, the likelihood of developing postoperative respiratory complications increased slightly. Prolonged operative time was identified as a significant risk factor for postoperative respiratory complications. Longer surgery time may increase risks such as prolonged anesthesia exposure, greater fluid shifts, and heightened intraoperative stress, all of which can impair respiratory function. Specifically, extended operative times can lead to reduced lung compliance, impaired gas exchange, and an elevated risk of postoperative respiratory infections or airway (15,16).

Another crucial factor contributing to the heightened risk of respiratory complications is the extended pneumoperitoneum associated with prolonged operative time. Longer durations of pneumoperitoneum increase intra-abdominal pressure (IAP), which in turn elevates airway pressure and decreases lung compliance, adding additional strain to the respiratory system. This increases the likelihood of postoperative respiratory complications. Moreover, prolonged pneumoperitoneum is associated with hypercapnia due to compromised ventilation, further burdening respiratory function. Additionally, prolonged pneumoperitoneum can contribute to the development of subcutaneous emphysema, a condition where gas is trapped beneath the skin, potentially exacerbating respiratory challenges postoperatively. The combined effects of elevated airway pressure, hypercapnia, and subcutaneous emphysema increase the risk of complications such as respiratory infections, atelectasis, and impaired gas exchange (17,18).

Although multivariate analysis did not retain operative time as an independent risk factor, its impact should not be overlooked. Prolonged operative time often serves as a surrogate marker for more complex procedures or intraoperative difficulties, which may indirectly increase the likelihood of respiratory complications. Therefore, strategies aimed at reducing operative time, where feasible, may help mitigate the risk of postoperative respiratory issues following RLA.

The impact of tumor laterality (left vs. right side) on complication rates following LA remains a topic of debate. A meta-analysis indicated that right-sided LA is associated with increased estimated blood loss and a higher conversion rate compared to left-sided procedures. These findings were particularly pronounced in studies using the transperitoneal approach (19). The finding that right-sided RLA is linked to a higher risk of respiratory complications aligns with existing literature suggesting anatomical and physiological challenges inherent to right-sided surgeries. These differences may be attributed to the distinct anatomical and vascular characteristics of the right adrenal gland compared to the left. The right adrenal gland drains directly into the inferior vena cava via a short central vein and is partially located behind the vena cava, which complicates the surgical approach (20). In addition, the proximity of the right adrenal gland to critical structures, such as the liver and diaphragm, may contribute to these increased risks. The finding that right-sided RLA is an independent risk factor aligns with prior evidence highlighting the anatomical and technical challenges associated with right-sided adrenal surgery. The right adrenal gland’s proximity to critical structures, such as the inferior vena cava, liver, and diaphragm, increases the complexity of surgical maneuvers and may elevate the risk of perioperative complications, including respiratory compromise. As a result, performing right-sided LA presents greater challenges compared to left-sided procedures due to the unique anatomical features of the right adrenal gland (21). It is crucial for surgeons to consider these factors during preoperative planning and patient counseling, emphasizing the importance of tailored approaches to surgical interventions based on the specific anatomical context.

Patient-specific factors and preoperative comorbidities, such as CVD, diabetes, hypertension, and respiratory disorders, are recognized predictive risk factors for perioperative complications in various types of surgeries (11,22). Laparoscopic surgery, in particular, necessitates maintaining an IAP of 12 to 15 mmHg, typically achieved through carbon dioxide (CO₂) insufflation. The elevated IAP and hypercapnia induced by CO₂ are major contributors to cardiovascular, respiratory, and renal system disturbances (17,23). The accumulation of CO₂ in the circulatory system and the resulting decrease in arterial pH can cause systemic vasodilation, myocardial depression, exacerbation of pulmonary hypertension, and arrhythmias. Patients with chronic obstructive pulmonary disease or pulmonary hypertension are particularly prone to intraoperative hypercapnia, which can impair respiratory function and lead to complications such as hypoxemia, reduced pulmonary compliance, and impaired microvascular perfusion (24). As a result, prolonged operative and anesthetic durations further increase the risk of postoperative respiratory complications following RLA.

This study has identified key risk factors associated with respiratory complications following RLA, including surgical complexity, right-sided RLA, and preoperative respiratory disease comorbidity. These findings underscore the importance of comprehensive preoperative assessments, particularly in patients undergoing more complex procedures or those with pre-existing respiratory disease. The identification of key risk factors for postoperative respiratory complications has significant clinical implications. Surgeons can use this information to refine perioperative risk stratification and implement targeted strategies to mitigate these risks. For instance, optimizing preoperative management of patients with known respiratory comorbidities and minimizing operative time through enhanced surgical techniques or team efficiency could reduce the likelihood of complications. Additionally, the recognition of right-sided RLA as a higher-risk procedure necessitates tailored perioperative planning, including closer intraoperative monitoring and postoperative respiratory support for these patients.

Furthermore, the results highlight the critical need for a multidisciplinary approach in the preoperative evaluation and management of RLA patients, particularly those at higher risk. Collaboration between urologists, anesthesiologists, and respiratory specialists is essential for the successful management of patients with heightened surgical complexity or respiratory comorbidities, ensuring better perioperative care and minimizing the risk of adverse respiratory events. By addressing these risks proactively, the study provides valuable insights that could inform clinical decision-making and perioperative strategies, contributing to safer and more effective surgical outcomes.

However, there are several limitations in the present study. First, its retrospective design introduces the possibility of selection and information bias due to variability in medical record documentation. Second, as a single-center study, the generalizability of the findings may be limited, and the results may not be applicable to other institutions with different surgical techniques or patient populations. Additionally, while we identified key risk factors for respiratory complications, other unexamined variables—such as anesthetic protocols or postoperative care differences-could also impact outcomes. Further multicenter, prospective studies are needed to validate these findings and improve predictive models.

Conclusions

In conclusion, our study identifies several critical risk factors for postoperative respiratory complications in patients undergoing RLA. By recognizing these factors, clinicians can better stratify risks and develop targeted preoperative management strategies aiming at minimizing complications. Future research should focus on validating these findings in larger cohorts and investigating interventions that could effectively reduce the risk of respiratory complications in this patient population.

Acknowledgments

Funding: None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://gs.amegroups.com/article/view/10.21037/gs-24-433/rc

Data Sharing Statement: Available at https://gs.amegroups.com/article/view/10.21037/gs-24-433/dss

Peer Review File: Available at https://gs.amegroups.com/article/view/10.21037/gs-24-433/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://gs.amegroups.com/article/view/10.21037/gs-24-433/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki (as revised in 2013). This study protocol was approved by the ethics committee of Beijing Anzhen Hospital (No. 2024249X). Individual consent for this retrospective analysis was waived.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Utsumi T, Iijima S, Sugizaki Y, et al. Laparoscopic adrenalectomy for adrenal tumors with endocrine activity: Perioperative management pathways for reduced complications and improved outcomes. Int J Urol 2023;30:818-26. [Crossref] [PubMed]
2. Conzo G, Patrone R, Flagiello L, et al. Impact of Current Technology in Laparoscopic Adrenalectomy: 20 Years of Experience in the Treatment of 254 Consecutive Clinical Cases. J Clin Med 2023;12:4384. [Crossref] [PubMed]
3. Kwak J, Lee KE. Minimally Invasive Adrenal Surgery. Endocrinol Metab (Seoul) 2020;35:774-83. [Crossref] [PubMed]
4. Inversini D, Manfredini L, Galli F, et al. Risk factors for complications after robotic adrenalectomy: a review. Gland Surg 2020;9:826-30. [Crossref] [PubMed]
5. Rodríguez-Hermosa JI, Planellas-Giné P, Cornejo L, et al. Comparison of Outcomes between Obese and Nonobese Patients in Laparoscopic Adrenalectomy: A Cohort Study. Dig Surg 2021;38:237-46. [Crossref] [PubMed]
6. Prudhomme T, Roumiguié M, Gas J, et al. Comparison between retroperitoneal and transperitoneal laparoscopic adrenalectomy: Are both equally safe? J Visc Surg 2021;158:204-10. [Crossref] [PubMed]
7. Liu Z, Li DW, Yan L, et al. Comparison of lateral transperitoneal and retroperitoneal approaches for homolateral laparoscopic adrenalectomy. BMC Surg 2021;21:432. [Crossref] [PubMed]
8. Limberg J, Ullmann TM, Gray KD, et al. Laparoscopic Adrenalectomy Has the Same Operative Risk as Routine Laparoscopic Cholecystectomy. J Surg Res 2019;241:228-34. [Crossref] [PubMed]
9. Conzo G, Gambardella C, Candela G, et al. Single center experience with laparoscopic adrenalectomy on a large clinical series. BMC Surg 2018;18:2. [Crossref] [PubMed]
10. Chen Y, Scholten A, Chomsky-Higgins K, et al. Risk Factors Associated With Perioperative Complications and Prolonged Length of Stay After Laparoscopic Adrenalectomy. JAMA Surg 2018;153:1036-41. [Crossref] [PubMed]
11. He J, Zhao J, Luo Y, et al. Establishment and validation of a nomogram for predicting perioperative complications of retroperitoneal laparoscopic adrenalectomy. Transl Androl Urol 2023;12:572-85. [Crossref] [PubMed]
12. Dindo D, Demartines N, Clavien PA. Classification of surgical complications: a new proposal with evaluation in a cohort of 6336 patients and results of a survey. Ann Surg 2004;240:205-13. [Crossref] [PubMed]
13. Haeuser L, Marchese M, Noldus J, et al. Association between Operative Time and Short-Term Radical Cystectomy Complications. Urol Int 2023;107:273-9. [Crossref] [PubMed]
14. Wang DE, Bakshi C, Sugiyama G, et al. Does Operative Time Affect Complication Rate in Laparoscopic Cholecystectomy. Am Surg 2023;89:4479-84. [Crossref] [PubMed]
15. Schwartz J, Parsey D, Mundangepfupfu T, et al. Pre-operative patient optimization to prevent postoperative pulmonary complications-Insights and roles for the respiratory therapist: A narrative review. Can J Respir Ther 2020;56:79-85. [Crossref] [PubMed]
16. Sameed M, Choi H, Auron M, et al. Preoperative Pulmonary Risk Assessment. Respir Care 2021;66:1150-66. [Crossref] [PubMed]
17. Atkinson TM, Giraud GD, Togioka BM, et al. Cardiovascular and Ventilatory Consequences of Laparoscopic Surgery. Circulation 2017;135:700-10. [Crossref] [PubMed]
18. Bablekos GD, Michaelides SA, Analitis A, et al. Effects of laparoscopic cholecystectomy on lung function: a systematic review. World J Gastroenterol 2014;20:17603-17. [Crossref] [PubMed]
19. Wang Y, Yang Z, Chang X, et al. Right laparoscopic adrenalectomy vs. left laparoscopic adrenalectomy: a systematic review and meta-analysis. Wideochir Inne Tech Maloinwazyjne 2022;17:9-19. [Crossref] [PubMed]
20. Patrone R, Gambardella C, Romano RM, et al. The impact of the ultrasonic, bipolar and integrated energy devices in the adrenal gland surgery: literature review and our experience. BMC Surg 2019;18:123. [Crossref] [PubMed]
21. Gunseren KO, Cicek MC, Vuruskan H, et al. Challenging risk factors for right and left laparoscopic adrenalectomy: A single centre experience with 272 cases. Int Braz J Urol 2019;45:747-53. [Crossref] [PubMed]
22. Brunaud L, Nguyen-Thi PL, Mirallie E, et al. Predictive factors for postoperative morbidity after laparoscopic adrenalectomy for pheochromocytoma: a multicenter retrospective analysis in 225 patients. Surg Endosc 2016;30:1051-9. [Crossref] [PubMed]
23. Bickel A, Loberant N, Bersudsky M, et al. Overcoming reduced hepatic and renal perfusion caused by positive-pressure pneumoperitoneum. Arch Surg 2007;142:119-24; discussion 125. [Crossref] [PubMed]
24. Hoekstra LT, Ruys AT, Milstein DM, et al. Effects of prolonged pneumoperitoneum on hepatic perfusion during laparoscopy. Ann Surg 2013;257:302-7. [Crossref] [PubMed]