Discussion:
Although laparoscopic operations have that benefits of shorter hospital stay, minimal postoperative pain, and rapid return to work, they can also lead to unfavorable systemic side effects due to intraperitoneal CO2 insufflation and increased IAP. CO2insufflation in the abdominal region can cause an upward displacement in the diaphragm and an increase in the risk of regurgitation, a decrease in lung volume and compliance, an increase in airway resistance and ventilation perfusion rate. In addition, an increase in systemic vascular resistance and mean arterial pressure may cause a decrease in venous return due to the compression of the inferior vena cava, thereby leading to a decrease in cardiac output. During the operation, a decrease in the renal blood flow due to prolonged CO2PP, and consequently a decrease in the glomerular filtration rate and urine output may be observed (12). According to the 2006 definition of the World Society for the Abdominal Compartment Syndrome, an IAP of 12 mmHg or more is considered as intraabdominal hypertension (13). During PP, an increase in IAP and an increase in the central venous pressure occur. The increase in IAP also causes a decrease in the perfusion of the mesenteric artery, intestinal mucosa, and hepatic and splanchnic areas. In cases of massive pressure increases, cardiac output and hepatic lactate clearance decrease and fatal lactic acidosis may be seen (14). In their study comparing patients who underwent laparoscopic cholecystectomy by applying PP at 7 mmHg and 15 mmHg IAP, Dexter et al. showed that heart rate and mean arterial pressure increased in both groups, and cardiac output and stroke volume decreased in the 15 mmHg group (10 and 26%, respectively) (15). McLaughlin et al. reported a 30% decrease in cardiac output and stroke volume and a 60% increase in the mean arterial pressure after the application of 15 mmHg PP (16). High-pressure PP can cause the pooling of blood from intraabdominal organs in venous reservoirs, end-organ damage, and hypoperfusion ischemia in tissues and organs.
Temporary increases in hepatic transaminases can be seen in the early period after laparoscopic surgery. The major factor in this increase may be CO2 PP since more changes in hepatic parameters may occur in laparoscopy involving 14 mmHg CO2 PP compared to gasless laparoscopy (17). Tan et al. examined serum liver enzymes at 24 and 48 hours and seven days after laparotomy and laparoscopic surgery involving CO2 PP, and evaluated AST and ALT values ​​at postoperative hours 24 and 48. The authors reported that the AST and ALT values measured at postoperative hours 24 and 48 increased more in the laparoscopic CO2 PP group compared to the patients that underwent laparotomy. While there was a slight increase in the total and direct bilirubin values, no change was found in the ALP, LDH and GGT values (18).
The increase in CO2 PP in hepatic parameters may also be proportional to the increase in CO2 pressure and IAP. Morino et al. (19) also emphasized that the increase in liver enzymes in laparoscopy performed with 10 mmHg CO2 pneumoperitoneum was less than observed in higher-pressure CO2 PP. According to Bendet et al. (20), postoperative aminotransferase levels increase especially after laparoscopic cholecystectomy as a result of the damage of Kupffer and endothelial cells in laparoscopic procedures. Volz et al. argued that in a short surgical time, such as laparoscopic cholecystectomy, which involves an increase and decrease in IAP causes an undulation in the portal blood flow, and and this fluctuation leads to reperfusion damage on the organ blood flow, especially Kupfer and endothelial cells in hepatic sinusoids and is associated with an increase in liver enzymes (21). Hoekstra et al. applied 14 mmHg and 25 mmHg IAP in a pig model and investigated the effect of prolonged PP on liver function and perfusion using the indocyanine green clearance test and intraoperative hepatic hemodynamics measured by simultaneous reflection spectrophotometry (venous oxygen saturation StO2 and relative tissue hemoglobin concentration). As a result, the authors reported that no additional damage occurred in the liver due to prolonged PP during laparoscopic surgery (22).
In our study, in the two groups in which we performed LSG by applying CO2 PP with 10 mmHg and 13 mmHg pressure, we compared the preoperative and postoperative 6th-, 12th-and 48th-hour blood urea, creatinine, AST, ALT, GGT, ALP, total and direct bilirubin, PT and INR values of the patients. To the best of our knowledge, there is no study in the literature evaluating hepatic parameters after LSG performed with 10 mmHg and 13 mmHg IAP. In our study, there was no significant difference between the hepatic parameters of the two groups. In the literature, it has been suggested that there may be a decrease in the sinusoidal blood flow in the fatty liver at a level that can be detected in both microvascular level and on Doppler USG (23). As a result, ischemic preconditioning occurs in the fatty liver, which can lead to the liver tissue becoming resistant to ischemic-reperfusion damage (24). Therefore, we consider that in our sample, the presence of morbidly obese patients with fatty liver in both groups may have resulted in non-significant differences in hepatic parameters.
Taura et al. measured blood lactate levels in different IAP groups (10-15 mmHg) among patients who underwent laparoscopic sigmoidectomy and showed that as IAP increased (maximum 15 mmHg), the lactate values also ​​increased. Berg et al. reported that the lactate values ​​increased from 1.12 to 1.159 mmol with PP (25).
Oliguria is a common condition observed during laparoscopic surgery. Razvi et al. argued that renal dysfunction occurred as a result of compression in both the renal parenchyma and renal arteries and veins as a result of increased IAP (26). Studies have shown that when IAP increases from 0 mmHg to 20 mmHg, vascular resistance increases by 555%, the renal glomerular filtration rate decreases by 25%, and the flow reduction in the renal vein can continue for two hours postoperatively (27). In our study, we found no difference between the two groups in terms of renal function test results. In a randomized controlled study involving 90 patients admitted to the hospital with the diagnosis of symptomatic cholelithiasis, laparoscopic cholecystectomy was performed with CO2 PP at 7 mmHg, 10 mmHg and 13 mmHg pressure values, and the total antioxidant status, total oxidant status, ischemia-modified albumin (IMA), IMA-to-serum albumin ratio, oxidative stress index and albumin parameters were evaluated. As a result, the authors observed that oxidative stress markers were increased values ​​at higher IAP levels (28).
In the recent past, two randomized controlled studies, one including laparoscopic colorectal surgery (IPPCollapse-II) and the other bariatric surgery, were undertaken to evaluate the effect of low IAP on the surgical area, duration of surgery, pain score, and postoperative complications compared to a standard pressure group, and it was argued that the low-pressure group had lower pain scores and a clear and good surgical appearance compared to the standard pressure group (29). The European Association for Endoscopic Surgery, taking into account the potential negative effects of PP, especially on cardiopulmonary functions and postoperative pain, recommends that PP planned as part of laparoscopic surgery should be performed using the minimum pressure that would allow an adequate view of the surgical area rather than the application of a standard pressure (30). In addition, Sherwani et al. recommended the use of PP with the lowest CO2 pressure as possible during laparoscopic operations that are expected to continue for an extended time in elderly people and patients with comorbidities, such as cardiovascular diseases (31). Another benefit of a low IAP is that it can be a facilitator for central venous catheterization (CVC), which involves the placement of a catheter often at the junction of the superior vena cava-right atrium via IJV and the subclavian vein (SCV) (11). CVC is used for various reasons, such as hemodynamic monitoring and drug administration, especially in patients who are hemodynamically unstable and/or those planned to undergo major surgery (32). Today, CVC is not routinely used preoperatively in laparoscopic surgery for the monitoring of patients with a low ASA grade. However, CVC may be urgently needed intraoperatively in case of cardiovascular failure and respiratory complications that arise during laparoscopic surgery. Although some centers benefit from USG in CVC, many centers still perform the procedure blindly. The diameter of the target central vein (internal jugular or subclavian) and the blood volume within the vein may affect the success of the procedure during both USG-guided and blind CVC. Since the media layers of the veins containing muscle are very thin and the veins do not have tension that can resist pressures unlike arteries, collapse may occur due to the pressure effect on the target vein during skin puncture with the Seldinger needle. In USG-guided catheterization, the weight of the probe may cause a collapsed vein. A larger central venous diameter and greater blood volume may be useful in counteracting the venous collapse caused by this pressure effect and can increase the success of venous puncture. During CVC, internal carotid artery puncture and pneumothorax are complications that can have serious consequences (33). Kusminsky et al. emphasized that hypovolemia and BMI > 30 were risk factors for CVC (34). The patients in our study were also in the high-risk group for CVC; therefore, we consider that the results of our study are important. Keeping IAP as low as possible during laparoscopy can contribute to preventing the development of this complication, as well as eliminating the need for emergency CVC during the operation.
It has been shown that the use of PEEP, Trendelenburg position, and different IAP values ​​during laparoscopic operations have significant effects on the cross-sectional area (CSA) during intravenous catheterization. PP applied with a pressure of 12 mmHg causes significant changes in IJV and SCV in both expiration and inspiration. In the study conducted, it was thought that the measurements in the desufflation period provided more IJV CSA than the basal measurements, which was probably caused by the high intrathoracic pressure due to mechanical ventilation. It is known that venous flow decreases as a result of increased resistance to venous return in the abdomen and extremities after increased IAP (35). In our study, we observed higher values ​​of the right IJV diameter and volume in LSG applied with 10 mmHg IAP compared to the 13 mmHg IAP group. According to our results, as the IJV diameter and the blood volume increased under 10 mmHg IAP, there were fewer collapses caused by puncture during CVC and compression due to the USG probe. These results of our study can be interpreted as indicating that a low IAP can increase the feasibility of CVC. However, there is a need for further on this subject.