Tumor implantation following laparoscopy using different insufflation gases

Background: Laparoscopic manipulation of malignancies is associated with an increased incidence of metastasis to port sites in experimental models. This study investigated the effect of different insufflation gases on the implantation of a tumor cell suspension following laparoscopic surgery in an established small animal model. Methods: Forty Dark Agouti rats underwent laparoscopy and the introduction into the peritoneal cavity of a tumor cell suspension. The insufflating gas used for each procedure was one of the following gases (10 rats in each group): carbon dioxide (CO₂), nitrous oxide (N₂O), helium, and air. The rats were killed 7 days after surgery, and the peritoneal cavity and port sites were examined for the presence of tumor. Results: Although no significant differences were seen between air, CO₂, and N₂O insufflation groups, tumor involvement of peritoneal surfaces was less likely following helium insufflation. Conclusion: The results of this study suggest that tumor metastasis to port sites following laparoscopic surgery may be influenced by the choice of insufflation gas. In this study, helium was associated with reduced tumor growth.     

Tumour implantation following laparoscopy using different insufflation gases

Background : Because of the possibility of intraperitoneal seeding and port‐site recurrences following laparoscopic surgery, the role of laparoscopy in cancer surgery remains controversial. Previous experimental studies have suggested that chemical, metabolic and immunological changes following carbon dioxide (CO₂) insufflation may be responsible for this phenomenon. Earlier experimental studies done by the University of Adelaide Department of Surgery have also shown that helium insufflation is associated with none of the adverse changes brought about by CO₂ insufflation. Helium insufflation is also associated with lower rates of intra‐abdominal tumour spread. The aim of this study was to determine whether these identified benefits apply to inert gases in general. Methods : Twenty‐four Dark Agouti rats were randomized to undergo laparoscopy with 40 min insufflation using one of the following four gases (six rats in each group); CO₂, helium, argon and nitrogen. A tumour cell suspension was injected into the abdominal cavity at the beginning of laparoscopy. The rats were killed 7 days after surgery, and the peritoneal cavity and port sites were examined for the presence of tumour. Results : Rats undergoing helium insufflation, had the least number of port‐site recurrences and the least amount of intraperitoneal tumour spread. Argon and nitrogen pneumoperitoneum were associated with a large number of port‐site recurrences and widespread tumour seeding. The effect of CO₂ insufflation was intermediate. Conclusion : The choice of insufflation gas influences the incidence of port‐site metastases and the degree of intraperitoneal tumour spread following laparoscopic cancer surgery. The reduced port‐site recurrences and intraperitoneal spread that followed helium pneumoperitoneum is likely to be a unique property of this gas rather than a property of inert gases in general.     

Carbon dioxide embolism during laparoscopy: effect of insufflation pressure in pigs.

Carbon dioxide embolism is a rare but potentially devastating complication of laparoscopy. To determine the effects of insufflation pressure on the mortality from carbon dioxide embolism, six swine had intravascular insufflation with carbon dioxide for 30 seconds using a Karl Storz insufflator at a flow rate of 35 mL/kg/min. The initial insufflation pressure was 15 mm Hg. Following recovery from the first embolism, intravascular insufflation using a pressure of 20 mm Hg at the same flow rate was performed in the surviving animals. Significantly less carbon dioxide (8.3 +/- 2.7 versus 16.7 +/- 3.9 mL/kg; p < 0.02) was insufflated intravascularly at 15 mm Hg than at 20 mm Hg pressure. All of the pigs insufflated at 15 mm Hg pressure with a flow rate of 35 mL/kg/min survived. In contrast, 4 of the 5 pigs insufflated at 20 mm Hg pressure died. The surviving pig died when insufflated with 25 mm Hg pressure following an embolism of 15.7 mL/kg. Intravascular injection was often associated with an initial rise in end-tidal carbon dioxide tension, followed by a rapid fall in all cases where the embolism proved fatal. Insufflation should be begun with a low pressure and a slow flow rate to limit the volume of gas embolized in the event of inadvertent venous cannulation. Insufflation should immediately be stopped if a sudden change in end-tidal carbon dioxide tension occurs.     

Experimental study of peritoneal blood flow and insufflation pressure during laparoscopy

BACKGROUND: Port-site metastases after laparoscopic surgery may occur with greater frequency than would be expected following open resection of intra-abdominal malignancies, but the causal mechanism for this is incompletely understood. The possibility that insufflation may increase peritoneal blood flow producing a wound environment conducive to the formation of metastases was investigated.METHODS: The effects of insufflation gas type and pressure were studied in 30-kg female pigs. Pigs were divided into five groups, which were subjected to insufflation at 12 mmHg pressure with helium, insufflation at 12, 8 or 4 mmHg pressure with carbon dioxide, or laparotomy. A microsphere technique utilizing two distinct radiotracers, 99mTc-labelled macroaggregated albumin (MAA) and 51Cr-labelled MAA, was used to study blood flow to the peritoneum, liver and kidneys.RESULTS: Insufflation with carbon dioxide or helium gases had no effect on renal (P < 0.09) or hepatic blood flow (P = 0.54). However, insufflation significantly increased peritoneal blood flow when carbon dioxide (P < 0.05), but not when helium (P = 0.99), was used as the insufflating gas.CONCLUSION: These data suggest that blood flow within the peritoneum is influenced by insufflation with carbon dioxide. It is conceivable that such hyperaemia could increase the propensity for implanted tumour cells to metastasize in these sites following laparoscopy.     

Oncological effects of insufflation with different gases and a gasless procedure in rats

Background: The validity of using carbon dioxide (CO₂) pneumoperitoneum in laparoscopic tumor surgery has not been investigated thoroughly. The oncologic effects of a gasless procedure and insufflation with different gases were compared in rats. Methods: In all the experiments, Donryu rats were randomized to receive a gasless procedure; to receive insufflation with CO₂, helium, or air at 10 mmHg for 30 min, or to serve as control subjects without insufflation. In experiment 1, involving 60 rats, ascites hepatoma AH130 cells were inoculated intraperitoneally just before the procedures. The S-phase fraction of the intraperitoneal tumor cells was determined using a flow cytometry on day 7. In experiment 2, 60 rats injected intraperitoneally with latex particles received one of the procedures. At the end of the procedure, peritoneal macrophages were harvested to determine the number of phagocytosed particles. In experiment 3, 75 rats inoculated intraperitoneally with AH130 cells received one of the procedures for 5 consecutive days and were followed for survival analysis. Results: Experiment 1: The S-phase fraction was lower after insufflation with air or helium (p < 0.01) than with the anesthesia control condition. Insufflation with CO₂ showed a higher S-phase fraction than the gasless procedure or insufflation with air or helium ( p < 0.01). Experiment 2: The phagocytotic activity of peritoneal macrophages was increased by insufflation with helium and air, as compared with the control condition ( p < 0.01). Insufflation with CO₂ deteriorated the phagocytotic activity more than the gasless procedure ( p < 0.05) or insufflation with air or helium ( p < 0.001). Experiment 3: Insufflation with gases demonstrated shorter survival than the anesthesia control condition or the gasless procedure regardless of the gases used (p < 0.01). Conclusions: These results suggest that the choice of gases may affect the proliferation of tumor cells and the phagocytotic activity of peritoneal macrophages, insufflation itself may promote tumor spread regardless of the gases used, and the gasless procedure may be oncologically advantageous in this animal model.     

腹腔镜二氧化碳腹腔内与腹膜外充气的比较

用家兔对二种不同的腹腔镜入路进行充气实验研究，腹腔内组动脉二氧化碳分压平均升高１．４８ｋＰａ（１ｋＰａ＝７．５ｍｍＨｇ）；腹膜外组动脉二氧化碳分压平均升高０．６９ｋＰａ。提示二氧化碳在腹膜外充气时比在腹腔内充气时全身吸收要少，同时提示动脉血ｐＨ值和氧分压在两种入路时均无明显变化。进一步对二组行不同入路腹腔镜手术患者的血气进行分析比较，发现二组患者动脉血二氧化碳分压均有明显升高，血ｐＨ值均有明显下降，但二组间的血气变化无明显差异。考虑腹腔镜经腹入路的合并症及泌尿系统的特点，认为经腹膜外入路对多数泌尿系疾病更适宜。     

Gas embolism during laparoscopy

The use of laparoscopic surgery has grown considerably, and the occurrence of some accidents, albeit rare, is now reported. Among them, gas embolism can induce a bad postoperative outcome. We report seven cases of carbon dioxide embolism (CO₂) during laparoscopic surgery. In the seven cases gas embolism occurred during insufflation or a few minutes later. All the patients had a previous abdominal or pelvic surgical history. Five patients presented cardiac bradycardia or arrhythmia. Cardiovascular collapse or cyanosis was the first manifestation in three cases. Sudden bilateral mydriasis was the earliest neurologic sign, present in five cases. Finally, the gas embolism complication was lethal in two cases. In summary, this study strongly stresses the need for precise rules of prevention of gas embolism, and close monitoring of cardiac rhythm during insufflation of carbon dioxide. The patients who had previous surgery should be considered as a risk population.     

Experimental study of the effect of intraperitoneal heparin on tumour implantation following laparoscopy

BACKGROUND: Conclusions drawn from clinical reports of port site metastases following laparoscopic resection of intra-abdominal malignancy are now supported by a burgeoning experimental literature which suggests that laparoscopy promotes tumour metastasis to wounds. This study investigated the effect of intraperitoneal blood and heparin on the incidence of tumour cell implantation and port site metastasis. METHODS: Twenty-four Dark Agouti rats underwent laparoscopy with carbon dioxide insufflation and the instillation of a tumour cell suspension and/or blood into the peritoneal cavity. Rats were allocated randomly to one of the following study groups (six rats per group): (1) controls; (2) intraperitoneal blood (2 ml blood introduced from a syngeneic donor rat); (3) intraperitoneal heparin; (4) intraperitoneal blood and heparin. Rats were killed 7 days after the procedure, and the peritoneal cavity and port sites were examined for the presence of tumour. RESULTS: Tumour implantation and port site metastases were reduced by the intraperitoneal administration of heparin, but increased by the presence of intraperitoneal blood. CONCLUSION: The results of this study suggest that tumour implantation following laparoscopy is promoted by the presence of intraperitoneal blood and that this effect may be reduced by the use of intraperitoneal heparin.     

Venous air embolism following insufflation of the urethra

Venous air embolism following urethral inflation only scarcely documented: an extensive search of the literature yielded four papers relating to this subject. We report a new case of venous air embolism due to this uncommon etiology. Careful study revealed some common pathogenetic features with previously reported cases. Some important precautions can diminish the likelihood of gas embolism and reduce its fatal outcome in situations, similar to the kind mentioned.     

The effect of insufflation pressure on CO(2) pneumoperitoneum and embolism in piglets

We conducted this study to investigate the effect of insufflation pressure on the pathophysiology of CO(2) pneumoperitoneum and embolism in an infant model. Twenty anesthetized piglets had stepwise intraperitoneal insufflation with CO(2) for 15 min at pressures ranging from 5 to 20 mm Hg. The piglets were ventilated to baseline normocarbia (ETCO(2) = 30 mm Hg, PaCO(2) = 38 mm Hg) before beginning each insufflation. CO(2) was then insufflated IV in 15 of these piglets at the same pressures. There was no reduction of blood pressure or cardiac output with intraperitoneal insufflation, but the stroke volume declined significantly (*P < 0.05) from (mean +/- SE) 10.6 +/- 1.3 mL to 8.5 +/- 1.3* mL and from 10.0 +/- 1.4 mL to 7.2 +/- 1.2* mL at 15 and 20 mm Hg insufflation pressure, respectively. Abdominal insufflation at 5, 10, 15, and 20 mm Hg caused an increase in ETCO(2) to 31.7 +/- 0.8 mm Hg, 35.6 +/- 1.2* mm Hg, 37.5 +/- 1.5* mm Hg, and 40.1 +/- 1.8* mm Hg and in PaCO(2) to 41.1 +/- 1.3* mm Hg, 44.2 +/- 1.4* mm Hg, 49.9 +/- 1.8* mm Hg, and 53.0 +/- 2.1* mm Hg, respectively. In contrast, the ETCO(2)decreased to 19.4 +/- 1.5* mm Hg, 20.4 +/- 1.4 mm Hg, 15.2 +/- 2.1* mm Hg, and 10.6 +/- 2.0* mm Hg with IV insufflation using the same pressures. IV insufflation caused marked hypotension and mortality. As the insufflation pressure increased, the mortality increased (0 in 15, 1 in 15, 1 in 14, and 6 in 13* at 5, 10, 15, and 20 mm Hg; *P < 0.05 vs 0 in 15, 1 in 15, and 1 in 14). This study suggests that although intraperitoneal insufflation up to 20 mm Hg may be tolerated hemodynamically, the lowest possible pressure should be used to reduce hypercarbia. A low insufflation pressure may also prevent mortality from CO(2) embolism. IMPLICATIONS: The lowest pressure possible should be used when inflating the abdomen with CO(2) to perform a laparoscopy in babies. A low pressure allows better ventilation and may prevent mortality if CO(2) is accidentally injected into a vein.     

The effect of general anaesthesia on the haemodynamic events during laparoscopy with CO2–insufflation

Sixteen women were studied during elective diagnostic laparoscopy with CO2-insufflation to an intraabdominal pressure (IAP) of 2 kPa and Trendelenburg tilt to 30 degrees. They were allocated to either a halothane (Group I) or a balanced (Group II) anaesthesia with relaxation and controlled ventilation. Heart rate (HR), arterial pressure, stroke volume, CO2-elimination, end-tidal CO2 vol.% and total respiratory compliance (TRC) were the parameters measured, and mean arterial pressure (MAP), total peripheral resistance (TPR), stroke index (SI) and cardiac index (CI) were calculated. At maximum haemodynamic strain, SI and CI were on average reduced by 42% in both groups, without significant changes in HR and MAP. TPR increased by 50% in Group I and 100% in Group II. The reduction in SI was related to the changes in TRC. A small increment in CO2-elimination after CO2-insufflation was most pronounced in Group II. SI and CI did not reach the pre-insufflation values after return to the horizontal position and CO2-exsufflation. The haemodynamic differences between the two groups were small compared to the effects of the laparoscopy procedures.