Mingliang Tang, University of Chinese Academy of Sciences, China
These authors have contributed equally to this work
This is an open-access article distributed under the terms of the
Laparoscopic pyeloplasty is a minimally invasive approach for the therapy of infant ureteropelvic junction obstruction (UPJO), reliant on CO2 pneumoperitoneum insufflation. While the impact of CO2 insufflation on adult and older pediatric populations has been studied, its effects on infants remain less explored.
This prospective randomized controlled trial included infants with UPJO undergoing laparoscopic pyeloplasty. Patients were allocated to low pneumoperitoneum pressure (LPP, 5 mmHg) or high pneumoperitoneum pressure (HPP, 8 mmHg) groups. Surgical parameters, postoperative complications, acid-base balance, stress markers, inflammatory cytokines, and oxidative stress markers were evaluated and compared.
A total of 116 infants were analyzed. Preoperative characteristics were comparable between LPP and HPP groups. No significant differences in blood loss, operation time, or hospitalization time were observed. Postoperative complications were similar between groups. Acid-base balance analysis revealed a decrease in pH after pneumoperitoneum in both groups, with greater reductions in actual base excess and standard base excess in the HPP group. Stress markers, cytokines, and oxidative stress markers increased postoperatively in both groups, with higher levels in the HPP group.
HPP leads to more pronounced physiological responses, including acid-base alterations, stress reactions, and inflammatory cytokine elevations.
Ureteropelvic junction obstruction (UPJO) is a significant urological condition characterized by a constriction or partial blockage at the point where the renal pelvis connects with the ureter (
Laparoscopic pyeloplasty stands as a well-established and sophisticated surgical approach in the armamentarium for addressing UPJO (
Insufflation is a necessary prerequisite for laparoscopic surgery, with CO2 currently being the most commonly used insufflation gas in clinical practice (
This study is a prospective randomized controlled trial that enrolled infants with UPJO who were scheduled to undergo laparoscopic pyeloplasty at our hospital. All enrolled patients had unilateral UPJO, without any other complications, and did not have contraindications to laparoscopic surgery such as diffuse peritonitis with intestinal obstruction or abdominal hernias. Informed consent was obtained from the guardians of the patients. Utilizing a random number table, the patients were randomly allocated into two groups: the low pneumoperitoneum pressure (LPP, 5 mmHg) group and the high pneumoperitoneum pressure (HPP, 8 mmHg) group, with 58 cases in each group. The researchers were blinded to the participants’ group allocation. The study was approved by the Ethics Committee of Children's Hospital of Nanjing Medical University. The study was performed in strict accordance with the Declaration of Helsinki, Ethical Principles for Medical Research Involving Human Subjects. The registration number of this study in our hospital is #CTR-2020.568d4.
All patients underwent surgery under standardized anesthesia protocols performed by the same surgical team. General anesthesia with standardized endotracheal intubation was administered to all patients, and respiratory parameters were not adjusted during the surgery. The patients were positioned in a lateral decubitus position, tilted at 30 degrees towards the affected side. A two-port technique for laparoscopic pyeloplasty was employed for all cases. At the initiation of surgery, CO2 gas was insufflated into the abdominal cavity using a Stryker 1288 insufflator (Stryker, Kalamazoo, MI) at a rate of 1–1.5 L/min. In both groups, insufflation pressures were set to 5 mmHg and 8 mmHg, respectively, and maintained steadily throughout the procedure. At the conclusion of the surgery, all trocars were removed, and the peritoneum was released through the umbilical incision to thoroughly evacuate the CO2 gas from the abdominal cavity, thereby concluding the insufflation process.
The ‘Danish Radiometer ABL80 Blood Gas Analyzer’ (Radiometer, Copenhagen, Denmark) was employed to measure arterial blood parameters, including pH, arterial partial pressure of carbon dioxide (PaCO2), arterial partial pressure of oxygen (PaO2), actual base excess (ABE), and standard base excess (SBE), at four distinct time intervals: 5 min before insufflation, 5 min after insufflation, 30 min after insufflation, and 30 min after desufflation. Arterial blood samples were collected during each of these time points.
For both groups of patients, venous blood samples of 5 milliliters each were collected at three distinct time points: 5 min before insufflation, upon completion of surgery (during closure of the insufflation incisions), and 24 h postoperatively. These samples were subjected to anticoagulant treatment and subsequently placed in a low-temperature centrifuge at a speed of 3,000 rpm for 15 min. The resulting supernatant was extracted and stored in a −80℃ ultra-low temperature freezer (Haier, Qingdao, China).
Peripheral blood concentrations of interleukin (IL)-6 and tumor necrosis factor alpha (TNF-α) were measured using the enzyme-linked immunosorbent assay (ELISA) technique (R&D Systems, Minneapolis, MN). Stress response indicators, including cortisol and epinephrine concentrations, were assessed. Serum malondialdehyde (MDA) concentrations were determined using the thiobarbituric acid (TBA) colorimetric method, while serum superoxide dismutase (SOD) concentrations were assessed using the xanthine oxidase method (hydroxylamine method).
Data analysis was performed using SPSS 22.0 statistical software (SPSS, Chicago, IL). Descriptive statistics, including mean and standard deviation (SD), were used for continuous variables. Between-group comparisons were conducted using the
In total, 116 infants were analyzed.
Preoperative characteristics of infants with ureteropelvic junction obstruction (UPJO) who received the laparoscopic pyeloplasty under low (5 mmHg) and high (8 mmHg) CO2 pneumoperitoneum pressures.
| Characteristics | LPP ( |
HPP ( |
|
|---|---|---|---|
| Age (month) | 5.63 ± 1.27 | 5.34 ± 1.46 | 0.318 |
| Body mass index (kg/m2) | 16.91 ± 2.53 | 17.15 ± 2.21 | 0.401 |
| Gender | |||
| Boy | 45 (77.6%) | 42 (72.4%) | 0.669 |
| Girl | 13 (22.4%) | 16 (27.6%) | |
| Side of UPJO | |||
| Left | 41 (70.7%) | 46 (79.3%) | 0.391 |
| Right | 17 (29.3%) | 12 (20.7%) | |
| Severity of UPJO | |||
| Moderate | 47 (81%) | 50 (86.2%) | 0.617 |
| Severe | 11 (19%) | 8 (13.8%) | |
The data are presented as mean ± SD or
Comparisons of blood loss, operation time and hospitalization time between infants with ureteropelvic junction obstruction (UPJO) who received the laparoscopic pyeloplasty under low (5 mmHg) or high (8 mmHg) CO2 pneumoperitoneum pressures.
| Items | LPP ( |
HPP ( |
|
|---|---|---|---|
| Blood loss (ml) | 29.72 ± 5.91 | 30.56 ± 6.09 | 0.194 |
| Operation time (min) | 107.24 ± 23.86 | 110.71 ± 24.15 | 0.208 |
| Hospitalization time (day) | 8.67 ± 2.15 | 8.19 ± 2.38 | 0.372 |
The data are presented as mean ± SD. The comparisons of data were done by Mann-Whitney test.
Postoperative complications among infants who underwent laparoscopic pyeloplasty for were compared in
Comparisons of postoperative complications between infants with ureteropelvic junction obstruction (UPJO) who received the laparoscopic pyeloplasty under low (5 mmHg) or high (8 mmHg) CO2 pneumoperitoneum pressures.
| Items | LPP ( |
HPP ( |
|
|---|---|---|---|
| Incision infection | 1 (1.7%) | 0 (0%) | > 0.999 |
| Urinary extravasation | 2 (3.4%) | 1 (1.7%) | > 0.999 |
| Fever | 1 (1.7%) | 1 (1.7%) | > 0.999 |
| Hematuresis | 1 (1.7%) | 2 (3.4%) | > 0.999 |
| Total | 5 (8.6%) | 4 (6.9%) | > 0.999 |
The data are presented as
Comparisons of acid-base balance between infants with ureteropelvic junction obstruction (UPJO) who received the laparoscopic pyeloplasty under low (5 mmHg) or high (8 mmHg) CO2 pneumoperitoneum pressures.
| Parameters | Group | 5 min pre- pneumoperitoneum | 5 min post- pneumoperitoneum | 30 min post- pneumoperitoneum | 30 min after pneumoperitoneum release |
|---|---|---|---|---|---|
| PH | LPP ( |
7.42 ± 0.08 | 7.41 ± 0.07 | 7.36 ± 0.07 | 7.40 ± 0.08 |
| HPP ( |
7.43 ± 0.09 | 7.36 ± 0.06 | 7.21 ± 0.06 |
7.31 ± 0.07 |
|
| PaCO2 (mmHg) | LPP ( |
40.14 ± 3.71 | 42.98 ± 3.67 | 49.71 ± 4.09 |
40.04 ± 3.49 |
| HPP ( |
39.82 ± 3.88 | 46.02 ± 3.81 | 58.82 ± 4.25 |
49.72 ± 3.78 |
|
| PaO2 (mmHg) | LPP ( |
94.17 ± 3.91 | 93.82 ± 3.72 | 89.68 ± 4.02 | 92.46 ± 3.97 |
| HPP ( |
94.62 ± 3.84 | 92.19 ± 3.95 | 91.39 ± 3.84 | 93.77 ± 4.02 | |
| ABE (mM) | LPP ( |
1.98 ± 0.21 | 2.06 ± 0.23 | 2.28 ± 0.19 | 2.19 ± 0.26 |
| HPP ( |
1.91 ± 0.24 | 2.28 ± 0.31 | 2.81 ± 0.36 |
2.31 ± 0.33 | |
| SBE (mM) | LPP ( |
2.06 ± 0.25 | 2.21 ± 0.28 | 2.37 ± 0.31 | 2.42 ± 0.41 |
| HPP ( |
2.11 ± 0.28 | 2.38 ± 0.33 | 2.95 ± 0.39 |
2.46 ± 0.39 |
The data are presented as mean ± SD.
As shown in
Comparisons of stress indexes, inflammatory cytokines and oxidative stresses between infants with ureteropelvic junction obstruction (UPJO) who received the laparoscopic pyeloplasty under low (5 mmHg) or high (8 mmHg) CO2 pneumoperitoneum pressures.
| Parameters | Group | Before operation | End of the operation | 24 h after operation |
|---|---|---|---|---|
| Cortisol (nmol/L) | LPP ( |
155.42 ± 31.15 | 348.92 ± 42.28 |
189.73 ± 34.89 |
| HPP ( |
150.21 ± 32.64 | 462.81 ± 54.76 |
218.19 ± 38.44 | |
| Norepinephrine (pmol/L) | LPP ( |
894.77 ± 159.71 | 1,932.08 ± 266.71 |
979.05 ± 172.33 |
| HPP ( |
906.26 ± 152.63 | 2,538.27 ± 308.86 |
1,125.85 ± 190.04 | |
| IL-6 (pg/ml) | LPP ( |
27.74 ± 5.17 | 39.82 ± 9.81 |
31.73 ± 6.82 |
| HPP ( |
29.81 ± 6.36 | 52.15 ± 11.36 |
40.23 ± 7.05 |
|
| TNF-α (pg/ml) | LPP ( |
21.15 ± 4.32 | 33.83 ± 5.89 |
28.71 ± 5.62 |
| HPP ( |
19.96 ± 4.49 | 45.21 ± 8.72 |
37.77 ± 7.83 |
|
| MDA (nM) | LPP ( |
4.37 ± 0.93 | 5.41 ± 1.03 |
4.62 ± 0.98 |
| HPP ( |
4.41 ± 1.06 | 6.77 ± 1.12 |
4.94 ± 1.09 | |
| SOD (U/ml) | LPP ( |
73.26 ± 11.15 | 65.83 ± 12.09 | 69.94 ± 12.27 |
| HPP ( |
75.02 ± 12.81 | 51.81 ± 10.74 |
62.23 ± 11.36 |
The data are presented as mean ± SD.
UPJO represents a significant urological condition characterized by a constriction or partial blockage at the junction of the renal pelvis and ureter (
CO2 pneumoperitoneum is a requisite for laparoscopic surgeries, with CO2 gas being the most commonly employed insufflation agent (
This study delved into the effects of different CO2 pneumoperitoneum pressures during laparoscopic pyeloplasty on various parameters in infants with UPJO. The randomized controlled trial design ensured robust comparisons. The study provides a comprehensive overview of the preoperative characteristics of the included infants. Despite some differences in mean age, BMI, gender distribution, side of UPJO, and severity of UPJO between the LPP and HPP groups, these variations were not statistically significant. These results imply that the allocation of patients into the two pressure groups was relatively balanced in terms of baseline characteristics, reducing the potential for confounding factors.
The comparison of surgical indicators such as blood loss, operation time, and hospitalization time is of clinical relevance. The study demonstrates that there were no statistically significant differences in these indicators between the LPP and HPP groups. This suggests that variations in CO2 pneumoperitoneum pressures did not exert a significant impact on the surgical outcomes evaluated in this study. The consistency in these parameters across the pressure groups implies that both pressures could be considered safe and feasible for the laparoscopic pyeloplasty procedure in this specific patient population.
Postoperative complications are critical factors affecting patient recovery and clinical outcomes. The study's findings indicate that there were no statistically significant differences in the incidence of various complications, including incision infection, urinary extravasation, fever, and hematuria, between the LPP and HPP groups. These results suggest that the choice of CO2 pneumoperitoneum pressure might not be a primary determinant of the occurrence of these complications in infants undergoing laparoscopic pyeloplasty for UPJO.
The assessment of acid-base balance parameters provides insights into the potential physiological effects of CO2 pneumoperitoneum pressures on infants. The study demonstrates that both LPP (5 mmHg) and HPP (8 mmHg) pressures can lead to a decrease in pH values after 30 min of pneumoperitoneum compared to pre-pneumoperitoneum levels. Additionally, the HPP group experiences more significant reductions in ABE and SBE after 30 min of pneumoperitoneum compared to the LPP group. These findings indicate that higher CO2 pneumoperitoneum pressures might induce more pronounced respiratory acidosis and metabolic disturbances, especially when sustained over a certain duration.
The study's assessment of stress response, inflammatory cytokines, and oxidative stress markers sheds light on the physiological responses induced by varying CO2 pneumoperitoneum pressures. Notably, both LPP and HPP groups experienced an increase in stress markers, inflammatory cytokines, and oxidative stress markers at the end of the operation, with the HPP group showing more substantial increases. This suggests that both pressures trigger physiological responses, but the higher pressure of 8 mmHg induces a more prominent stress reaction and inflammation.
While this study provides valuable insights into the effects of different CO2 pneumoperitoneum pressures on infants undergoing laparoscopic pyeloplasty for UPJO, several limitations should be acknowledged. (1) The relatively small sample size of 116 patients, though adequately powered for the conducted analyses, might limit the generalizability of the findings. A larger, multicenter study involving a broader range of patient demographics would enhance the external validity of the results. (2) Conducted within a single medical institution, this study's findings might not be representative of the broader population due to potential institutional variations in surgical techniques, patient care, and anesthesia protocols. (3) The study's focus on short-term outcomes up to 24 h postoperatively provides insight into immediate effects but precludes a comprehensive assessment of longer-term implications. A longer follow-up period would be required to evaluate the persistence and evolution of the observed physiological changes. (4) This study exclusively focused on variations in CO2 pneumoperitoneum pressures while holding other parameters constant. The effects of altering other insufflation parameters, such as gas flow rate or duration, were not explored and could have contributed to a comprehensive understanding of their combined effects. (5) Only the levels of IL-6 and TNF-α were examined in the current study. To fully evaluate the inflammatory levels, other pro- and anti-inflammatory cytokines, such as IL-1β and IL-10, should be considered in the future work.
In conclusion, this study sheds light on the distinct effects of CO2 pneumoperitoneum pressures on various physiological parameters in infants undergoing laparoscopic pyeloplasty for UPJO. These findings emphasize the significance of carefully selecting insufflation pressures, particularly in the delicate pediatric population, to minimize physiological disturbances and enhance patient outcomes. This study contributes valuable insights to the field of pediatric laparoscopic surgery, guiding clinicians towards optimized perioperative care strategies.
The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.
The studies involving humans were approved by Children’s Hospital of Nanjing Medical Universit. The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study.
YP: Data curation, Funding acquisition, Resources, Supervision, Validation, Writing – original draft, Writing – review & editing. MZ: Data curation, Funding acquisition, Resources, Supervision, Validation, Writing – original draft, Writing – review & editing. CC: Data curation, Funding acquisition, Resources, Supervision, Validation, Writing – original draft, Writing – review & editing.
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