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.