Abdominal insufflation with CO2 causes peritoneal acidosis independent of systemic pH.

We have shown that the inflammation-attenuating effects of CO(2) pneumoperitoneum during laparoscopy are not due to changes in systemic pH. However, acidification of peritoneal macrophages in an in vitro CO(2) environment has been shown to reduce LPS-mediated cytokine release. We tested the hypothesis that the peritoneum is locally acidotic during abdominal insufflation with CO(2)--even when systemic pH is corrected. Rats (n = 20) were anesthetized and randomized into two groups: continued spontaneous ventilation (SV) or intubation and mechanical ventilation (MV). All animals were then subjected to abdominal insufflation with CO(2). Mean arterial pH among SV rats decreased significantly from baseline after 15 and 30 minutes of CO(2) pneumoperitoneum (7.329 --> 7.210 --> 7.191, P < 0.05), while arterial pH among MV rats remained relatively constant (7.388 --> 7.245 --> 7.316, P = NS). In contrast, peritoneal pH dropped significantly from baseline and remained low for both groups during CO(2) abdominal insufflation (SV 6.74 --> 6.41 --> 6.40, P < 0.05; MV 6.94 --> 6.45 --> 6.45, P < 0.05). In a second experiment, rats (n = 10) were randomized to receive abdominal insufflation with either CO(2) or helium. Abdominal insufflation with helium did not significantly affect peritoneal pH (7.10 --> 7.02 --> 6.95, P = NS), and the decrease in pH among CO(2)-insufflated animals was significant compared with helium-insufflated animals (P < 0.05). Peritoneal pH returned to baseline levels in all groups within 15 minutes of desufflation in both experiments. A significant local peritoneal acidosis occurs during laparoscopy which is specifically attributable to the use of CO(2) and which is independent of systemic pH. These data provide additional evidence that localized peritoneal acidosis is central to the mechanism of CO(2)-mediated attenuation of the inflammatory response following laparoscopic surgery.     

The oxidative effect of prolonged CO<Subscript>2</Subscript> pneumoperitoneum on renal tissue of rats

Background Despite its advantages, laparoscopic donor nephrectomy is associated with prolonged operation time, which could potentially increase oxidative stress in the graft. We performed the first experimental, randomized, controlled study with blind assessment of outcome to address this possibility.Methods Wistar–Albino rats were randomized into three groups. The animals in the control group were subjected to a sham operation under anesthesia; the animals in the other two groups were subjected to CO₂ pneumoperitoneum (Pp) for 120 and 240 min, respectively. The kidneys were removed at the end of each experiment. The concentrations of protein carbonyl and sulfhydryl (SH) groups and the activities of superoxide dismutase (SOD) were measured in renal tissue samples as markers of oxidative stress. Renal tissue samples were also evaluated histopathologically using light microscopy.Results Exposure to 120 min of Pp significantly increased the finding of oxidative stress in renal tissue samples, with an increase in protein carbonyl content and a decrease in protein sulfhydryls and tissue (SOD) activities. When exposure to Pp was prolonged from 120 min to 240 min, Pp associated oxidative stress was found to be increased. These changes occurred in the absence of light microscopical evidence of overt tissue damage.Conclusions In an experimental model resembling laparoscopic donor nephrectomy, we found that exposure of pneumoperitoneum prolonged from 120 min to 240 min acts as an additive factor with respect to causing increased oxidative stress in renal tissue. Because these effects imply subtle tissue injury that may contribute to the chronic demise of renal grafts obtained laparoscopically, avoiding the use of Pp if possible and keeping operation time less than 120 min during laparoscopic donor nephrectomy appear to be advisable.Poster presented at the 39th Congress of the European Renal Association and European Dialysis and Transplant Association, Copenhagen, Denmark, July 2002     

Peritoneal and systemic pH during pneumoperitoneum with CO<Subscript>2</Subscript> and helium in a pig model

Background Local peritoneal effects of laparoscopic gases might be important in peritoneal biology during and after laparoscopic surgery. The most commonly used gas, CO₂, is known to be well tolerated, but also causes changes in acid-base balance. Helium is an alternative gas for laparoscopy. Although safe, it is not widely used. In this study a method for monitoring peritoneal pH during laparoscopy was evaluated and peritoneal pH during CO₂ and helium pneumoperitoneum was studied as well as its systemic reflection in arterial pH. Methods For these experiments 20 pigs were used, with ten exposed to pneumoperitoneum with CO₂, and ten to helium. Peritoneal and sub-peritoneal pH were continuously measured before and during gas insufflation, during a 30-minute period with a pneumoperitoneum and during a 30-minute recovery period. Arterial blood-gases were collected immediately before gas insufflation, at its completion, at 30 minutes of pneumoperitoneum and after the recovery period. Results Peritoneal pH before gas insufflation was in all animals 7.4. An immediate local drop in pH (6.6) occurred in the peritoneum with CO₂ insufflation. During pneumoperitoneum pH declined further, stabilising at 6.4, but was restored after the recovery period (7.3). With helium, tissue pH increased slightly (7.5) during insufflation, followed by a continuous decrease during pneumoperitoneum and recovery, reaching 7.2. Systemic pH decreased significantly with CO₂ insufflation, and increased slightly during helium insufflation. Systemic pH showed co-variation with intra-peritoneal pH at the the end of insufflation and after 30 minutes of pneumoperitoneum. Conclusions Insufflation of CO₂ into the peritoneal cavity seemed to result in an immediate decrease in peritoneal pH, a response that might influence biological events. This peritoneal effect also seems to influence systemic acid-base balance, probably due to trans-peritoneal absorption.     

Accuracy of a point-of-care blood gas analyzer in gastric tonometry measurements of intramucosal pH (pHi) and P<Subscript>CO</Subscript><Subscript>2</Subscript> gap

Purpose We assessed the accuracy of a point-of-care blood gas analyzer in providing data from saline samples obtained by gastrointestinal tonometry (Tonometrics Catheter; Tonometrics Division, Instrumentarium, Helsinki, Finland) for the calculation of intramucosal pH (pHi) and the P_CO2 gap (intramucosal P_CO2 – Pa_CO2).Methods We compared the point-of-care analyzer (Opti; AVL Medical Instruments, Schaffhausen, Switzerland; Opt) with a conventional analyzer (Compact 2 AVL Medical Instruments, Schaffhausen; Elect) in a clinical study (Elect being taking as the standard). In an in vitro study, P_CO2 data of tonometer saline (Pr_CO2) from Opt and Elect were compared with P_CO2 data from a continuous air tonometer (Tonocap Tonometrics Division, Instrumentarium) for a bottle containing a mixed P_CO2 gas. Data were evaluated by the Bland-Altman method.Results In the clinical study, the bias (B) and precision (P) were: B = 0.223 and P = 0.056 for pHi, B = –14.0 and P = 2.43 (mmHg) for Pr_CO2, and B = –16.7 and P = 2.6 (mmHg) for the P_CO2 gap (n = 27). In the in vitro study, the bias between the two values (Pr_CO2 and bottle P_CO2) was –1.98mmHg and precision was 1.23mmHg for Elect, but for Opt, these values were –22.09mmHg and 3.15mmHg, respectively (n = 18).Conclusion Opt is not suitable for measuring pHi and the P_CO2 gap because it does not provide an accurate P_CO2 for tonometry saline.Part of this study was presented at the 20th International Symposium on Intensive Care and Emergency Medicine (Brussels, March, 2000).     

CO<Subscript>2</Subscript> pneumoperitoneum increases systemic but not local tumor spread after intraperitoneal murine neuroblastoma spillage in mice

Background  Minimally invasive techniques are increasingly used for biopsy and resection of neuroblastoma, but the impact on the behavior of spilled tumor cells is unknown. We aimed to investigate whether CO₂ pneumoperitoneum can affect local or systemic tumor manifestation after spillage of neuroblastoma cells into the peritoneal cavity. Methods  Murine neuroblastoma cells (Neuro2a, 1x10⁶) were inoculated into the peritoneal cavity of 25 male A/J mice, which subsequently underwent CO₂ pneumoperitoneum (n = 12) or laparotomy (n = 13) for 1 h. At the 28th postoperative day, local (peritoneal and surface of the gut) and systemic (liver, lung, spine) tumor spread was graded in a blinded manner (1–4 point scale) and specimens were histologically examined for tumor manifestation (hematoxylin and eosin stain) and tumor cell proliferation rate (Ki-67-stain). In the case of no visible lesion, five random sections were histologically examined. Peritoneal carcinosis was graded macroscopically. Results  Tumor manifestations were detected in 10 out of 12 (83%) animals after CO₂ pneumoperitoneum, and in 9 out of 13 (69%) after laparotomy (n.s.). Incidence of liver metastasis was higher after CO₂ pneumoperitoneum versus laparotomy (83% versus 31%; p < 0.05). Incidence and grading of peritoneal carcinosis was not significantly different between the groups (n.s.). Intrapulmonary metastasis was found in one mouse of each group, but no metastasis of the spine. However, the grading of liver metastasis was higher after CO₂ pneumoperitoneum compared to laparotomy (p < 0.05). Tumor cell proliferation (Ki-67 stain) in the liver did not differ between both groups. Moreover, proliferation always exceeded 50% of tumor cells, irrespective local or systemic tumor manifestation. Conclusions  CO₂ pneumoperitoneum increased intrahepatic metastasis, but not local peritoneal carcinosis in a murine neuroblastoma model. This suggests that laparoscopy could promote systemic dissemination of intraperitoneally spilled tumor cells when no chemotherapy is applied. It remains to be determined whether this is due to local immune suppression or direct modulation of tumor cell behavior.     

p53 expression and apoptosis in liver and spleen during CO<Subscript>2</Subscript> pneumoperitoneum

Backgrounds and aims  Laparoscopic surgery techniques have been increasingly preferred to classic laparotomy by surgeons since 1987. However, this method has some important adverse effects on intra-abdominal organs. The aim of this study is to evaluate the effects of different pressures of CO₂ on apoptosis and p53 expression in cells in liver and spleen. Methods  In total, 30 male Sprague–Dawley rats were used in the study. CO₂ was insufflated into the intra-abdominal cavity via angiocatheter cannule by an insufflator in two different pressures of 10 and 20 mm Hg for 60 min. However, in the control group, only cannule was inserted into the intra-abdominal cavity, but no gas was insufflated. After 60 min, the rats were killed and laparotomy was applied. The liver and spleen were excised. The samples were histologically processed and immunohistochemistry was applied. Results  All the data revealed that the number of apoptotic cells in liver and spleen increases in proportion to CO₂ pressure level. No p53 expression was detected in both organs. Conclusion  CO₂ pressure level and application time may affect on cells living in liver and spleen. High pressure and/or long application time may cause releasing of cytokines and superoxide radicals from these organs’ cells, and transient or serious organ dysfunctions may occur.     

CO2 abdominal insufflation pretreatment increases survival after a lipopolysaccharide-contaminated laparotomy

Carbon dioxide (CO₂)-pneumoperitoneum is known to favorably modify the systemic immune response during laparoscopic surgery. The presented studies were designed to determine whether treating animals with CO₂ abdominal insufflation before undergoing a lipopolysaccharide (LPS)-contaminated laparotomy would serve as “shock prophylaxis” and thus improve survival and attenuate cytokine production. Rats were randomized into five groups: CO₂-pneumoperitoneum, helium-pneumoperitoneum, anesthesia control, laparotomy/LPS control, and LPS only control. Animals in the first four groups all received a laparotomy and a lethal dose of LPS. Immediately preceding their laparotomy, animals in the pneumoperitoneum groups received a 30-minute pretreatment of abdominal insufflation with either CO₂ or helium. The anesthesia control group received a 30-minute pretreatment of isoflurane. Animal mortality was then recorded during the ensuing 72 hours. Subsequently, a similar protocol was repeated for measurements of cytokines. CO₂-pneumoperitoneum increased survival at 48 hours compared with LPS control (P<.05), and decreased interleukin-6 plasma levels at 2 hours (P<.05). Abdominal insufflation with CO₂ before the performance of a laparotomy contaminated with endotoxin increases survival and attenuates interleukin-6. The beneficial immune-modulating effects of CO₂-pneumoperitoneum endure after abdominal insufflation. CO₂-pneumoperitoneum pretreatment may improve outcomes among patients undergoing gastrointestinal surgery who are at high risk for abdominal fecal contamination. Presented at the Forty-Sixth Annual Meeting of The Society for Surgery of the Alimentary Tract, Chicago, Illinois, May 14–18, 2005 (poster presentation). Supported by R01-GM062899-02, National Institutes of Health, Bethesda, Maryland.     

Port-site metastasis after CO<Subscript>2</Subscript> pneumoperitoneum

Background Port-site metastasis is a continuing problem in laparoscopic cancer surgery. To clarify the role of adhesion molecules in the development of port-site metastasis, particularly with regard to prevention, we performed experiments in which port-site metastasis was inhibited using antibodies against extracellular matrix proteins or the active Arg–Gly–Asp (RGD) peptide after CO₂ pneumoperitoneum in a murine model.Methods We examined the development of port-site metastasis under the following conditions: (1) CO₂ pneumoperitoneum with or without hyaluronic acid and anti-integrin or anti-CD44 antibody and (2) CO₂ pneumoperitoneum and a RGD peptide or pseudo-RGD sequence peptide (FC-336). BALB/c mice (n = 130) were injected with 5 × 10⁵ human gastric cancer cells (MKN45) and either antibody or peptide, treated with CO₂ pneumoperitoneum, and injected intraperitoneally with antibody or peptide for 5 days. Three weeks after CO₂ pneumoperitoneum, the frequency and weight of port-site metastatic tumors were determined.Results Anti-integrin antibody significantly decreased the weight of port-site metastatic tumors without hyaluronic acid (control vs anti-integrin: 8.2 ± 7.1 vs 3.6 ± 4.5 mg; p < 0.05) but not the frequency of port-site metastases. With hyaluronic acid, the frequency of port-site metastasis and the weight of port-site metastatic tumors were significantly decreased both by anti-integrin and by anti-CD44 antibody (control vs anti-integrin and anti-CD44; 95% and 8.5 ± 7.2 mg vs 50% and 3.1 ± 4.3 mg and 55% and 3.3 ± 5.1 mg, respectively; p < 0.05). RGD peptide and FC-336 also inhibited port-site metastasis in a dose-dependent manner.Conclusion Cell adhesion molecules integrin and CD44 play an important role in the development of port-site metastasis after laparoscopic cancer surgery. Intraperitoneal injection of RGD peptide or pseudo-RGD sequence peptide (FC-336) can prevent port-site metastasis.     

Carbon dioxide pneumoperitoneum causes severe peritoneal acidosis,unaltered by heating,humidification, or bicarbonate in a porcine model

Background Carbon dioxide (CO₂) is the most common gas used for insufflation in laparoscopy, but its effects on peritoneal physiology are poorly understood. This study looks at the changes in peritoneal and bowel serosal pH during CO₂ pneumoperitoneum, and whether heating and humidification with or without bicarbonate alters the outcomes.Methods Twenty-one pigs divided into four groups as follows: (1) standard (STD) laparoscopy (n = 5); (2) heated and humidified (HH) laparoscopy (n = 6); (3) heated and humidified with bicarbonate (HHBI) laparoscopy (n = 5); and (4) laparotomy (n = 5). Peritoneal pH, bowel serosal pH, and arterial blood gas (ABG) were obtained at 15-min intervals for 3 h.Results Severe peritoneal acidosis (pH range 6.59–6.74) was observed in all laparoscopy groups, and this was unaltered by heating and humidification or the addition of bicarbonate. Bowel serosal acidosis was observed in all laparoscopy groups with onset of pneumoperitoneum, but it recovered after 45 minutes. No significant changes in peritoneal or bowel serosal pH were observed in the laparotomy group.Conclusion CO₂ pneumoperitoneum resulted in severe peritoneal acidosis that was unaltered by heating and humidification with or without bicarbonate. Alteration in peritoneal pH may conceivably be responsible for providing an environment favorable for tumor-cell implantation during laparoscopy.     

Peritoneal pH during laparoscopy is dependent on ambient gas environment: helium and nitrous oxide do not cause peritoneal acidosis

Background Little is know about the effects of different insufflation gases on peritoneal pH during laparoscopy. However, these changes may influence the intracellular signalling system, resulting in altered cell growth or adhesiveness. The aim of this study was to determine the effects of carbon dioxide (CO₂), nitrous oxide (N₂O), and helium (He) on parietal and visceral peritoneal pH. The effect of different intraabdominal pressures on parietal and visceral peritoneal pH was also examined.Methods We conducted both an ambient gas study and a pressure study. For the ambient gas study, 20 pigs were divided into the following four groups: (a) CO₂, (b) He, (c) N₂O, and (d) abdominal wall lift (Lift) laparoscopy. Parietal and visceral peritoneal pH were measured at 15 min intervals for 180 min. For the pressure study, 15 pigs were divided into the following three groups: (a) CO₂, (b) He, (c) N₂O laparoscopy. Baseline values were established for parietal and visceral peritoneal pH. Intraabdominal pressure was then increased stepwise at 1-mmHg intervals to 15 mmHg. After pressure was maintained for 15 min at each setting, parietal and visceral peritoneal pH were measured.Results Ambient gas environment was the major determinant of parietal peritoneal pH. Carbon dioxide caused parietal peritoneal acidosis. Helium, N₂O, and Lift caused alkalotic parietal peritoneal pH. Intraabdominal pressure had a minor effect on parietal peritoneal pH. At higher intraabdominal pressure (12–15 vs 5–8 mmHg), CO₂ caused a slight decrease in parietal peritoneal pH, whereas N₂O and He caused a slight increase in parietal peritoneal pH. Visceral peritoneal pH remained relatively unaffected during all studies.Conclusions Parietal peritoneal pH during laparoscopy was highly dependent on the ambient gas environment. The effect of intraabdominal pressure on parietal peritoneal pH was of minor significance. Carbon dioxide caused a slight worsening of parietal peritoneal acidosis at higher intraabdominal pressure, whereas, N₂O, He, and Lift did not cause parietal peritoneal acidosis.     

A randomized controlled study evaluating the effects of the temperature of insufflated CO<Subscript>2</Subscript> on core body temperature and blood gases (an experimental study)

Background Heated carbon dioxide (CO₂) was used for pneumoperitoneum (Pp) to prevent hypothermia. This study aimed to investigate the relationship between the temperature of the insufflated CO₂ and blood gases together with the core body temperature (CBT). Methods A prospective controlled study was performed with 24 pigs weighing approximately 20 kg randomized into four groups of 6 pigs each. A pneumoperitoneum at 12 mmHg of pressure was applied for 60 min with the pig under general anesthesia. The CO₂ temperature was 22°C in group 1, 37°C in group 2, and 7°C in group 3. In the “sham” group, pneumoperitoneum was not applied. Arterial blood pH and partial pressure of CO₂ (PaCO₂) were analyzed before insufflation, every 15 min during the pneumoperitoneum, and 15 min after the desufflation. The CBT was recorded before the insufflation, every 20 min during pneumoperitoneum, and 20 min after the desufflation. Blood gas analyses and CBT records for the “sham” group were performed at the same intervals. Results Arterial blood pH gradually decreased during pneumoperitoneum. At the 60th minute of pneumoperitoneum, a minimum decrease in arterial blood pH (0.04; p = 0.027) and a minimum increase in PaCO₂ (3.67; p = 0.027) were recorded in group 3, whereas a maximum decrease in arterial blood pH (0.18; p = 0.027) and a maximum increase in PaCO₂ (17.17; p = 0.027) were recorded in group 2. There was a significant negative correlation between PaCO₂ and arterial blood pH in all the groups (r = –0.993; p < 0.01). The mean values of CBT decreases were statistically significant in all the groups: group 1 (p = 0.023), group 2 (p = 0.026), group 3 (p = 0.026), and “sham” group (p = 0.024). Conclusions The changes in PaCO₂ were directly proportional and the changes in pH contrarily proportional to the temperature of the insufflated CO₂. Significant differences in CBT decreases were found between the groups receiving heated gas and room temperature gas and the groups receiving heated gas and gas below room temperature.     

Pressure-autoregulation,CO<Subscript>2</Subscript> reactivity and asymmetry of haemodynamic parameters in patients with carotid artery stenotic disease. A clinical appraisal

Summary ¶Objectives. Patients with carotid artery stenotic disease and poor cerebral haemodynamic reserve are in increased risk of stroke. Haemodynamic reserve can be estimated by measuring cerebrovascular reactivity induced by breathing CO₂ and pressure-autoregulation by analyzing spontaneous slow fluctuation in arterial pressure and MCA blood flow velocity. We evaluated the relationship between clinical status, CO₂ reactivity, pressure-autoregulation and other haemodynamic variables derived from Transcranial Doppler ultrasonography in patients with carotid artery disease. Methods. 38 patients were investigated. Arterial pressure and blood flow velocity were monitored during CO₂ reactivity tests. Arterial pressure-corrected and non-corrected indices of CO₂ reactivity were calculated to compare an influence of rise in arterial pressure during the test. The pressure-autoregulation index was calculated as correlation coefficient between slow waves in blood flow velocity and arterial pressure. Results. The increase in CO₂ produced a consistent rise in arterial pressure and blood flow velocity and weakened the pressure autoregulation. The value of pressure-corrected CO₂ reactivity was lower (p<0.0001) than the non-corrected one, indicating that the rise in arterial pressure during the test tends to over-estimate CO₂ reactivity. The pressure-corrected reactivity was correlated with pressure autoregulation (r=–0.46; p<0.005). Both CO₂ reactivity and pressure-autoregulation index correlated with a degree of carotid artery stenosis. Side-to-side difference of TCD pulsatility index demonstrated a close relationship with the asymmetry of stenosis (r=–0.61; p<0.0002) and symptoms (r=–0.49; p<0.003). Conclusions. When calculating CO₂ reactivity in patients with carotid artery disease, changes in arterial pressure should be considered. Both CO₂ reactivity and pressure-autoregulation describe the magnitude of haemodynamic deficit caused by stenosis, pulsatility index expresses the asymmetry of stenosis.     

The effect of different levels of peritoneal CO<Subscript>2</Subscript> pressure on bleeding time of spleen capsule injury

Aims: The authors, in contrast to similar injuries with open surgery, had observed spontaneous hemostasis of relatively large spleen capsule injuries during laparoscopic surgery. Methods: Standard spleen injuries were carried out in 5 anesthetized mongrel dogs at different CO₂ pressures and in open surgery. Bleeding was checked every minute by wiping around the injury but not removing the clot. Bleeding time was measured until no more oozing was detected. At every pressure level 3-3 measurements were done and analyzed. Parenchymal pressure of the spleen and systemic blood pressure were detected with direct catheter implantation. Results: In open surgery the average bleeding time was 15.2 min; at 5, 15, and 25 mmHg CO₂ pressures bleeding times were 12.3, 10.6, and 9.8 min, respectively. The parenchymal pressure of the spleen (5–6 mmHg) rose synchronously with peritoneal pressure, but no significant changes in systemic blood pressure were seen. Conclusion: Peritoneal CO₂ pressure may counterweight the parenchymal pressure of the spleen, thus helping hemostasis. There seems to be an inverse proportion between peritoneal pressure and bleeding time. In case of spleen capsule injury during laparoscopic surgery, chances for spontaneous hemostasis are much better compared to open surgery. Attention must be paid to maintain adequate peritoneal pressure.     

Extrakorporale CO<Subscript>2</Subscript>-Elimination als Alternative zur Tracheotomie bei Weaningversagen

We report a patient with chest trauma who was admitted to the ICU after surgery. As he fulfilled protocol-based criteria, he was extubated 7 days after admission. However, despite intermittent non-invasive ventilation, the patient had to be re-intubated on day 10 owing to progressive hypercapnia. We decided to support the patient with a mid-flow veno-venous extracorporeal carbon dioxide removal (ECCO₂?R) system instead of a tracheotomy. Sufficient CO₂ removal was established with a blood flow of 1.5?l/min and the patient was successfully extubated within a few hours. After 5 days of ECCO₂?R the patient could be weaned and transferred to a general ward in a stable condition.     

Benefits of the use of the CO<Subscript>2</Subscript> laser in orthodontics

Esthetics is an important factor for patients seeking orthodontic treatment, and not always is the orthodontist able to make adjustments on the gingival contour, and this aspect is neglected. Many orthodontists are familiar with the name laser. However, there is a lack of information regarding their application on the orthodontic practice. There are several options for the use of CO₂ lasers on surgical procedures of interest to orthodontists, especially on soft tissues. There is no evidence that the use of the CO₂ laser has any side effect or contraindication on surgical procedures. This paper reports a series of surgical procedures carried out on orthodontic patients. It is concluded that the carbon dioxide laser not only allows surgeons to enhance current surgical options for treatment but also have contributed to the evolution of a variety of new procedures that are now commonplace in oral surgery, and its use shows several benefits for the orthodontic patient.     

Comparison of the effects of gasless procedure,CO<Subscript>2</Subscript>-pneumoperitoneum,and laparotomy on splenic and hepatic natural killer activity in a rat model

Background: Natural killer (NK) activity plays an important role in the prevention of tumor metastasis. However, few studies compared changes in NK activities between gas(less) laparoscopy and open surgery. Materials and methods: Donryu rats were randomized to 4 groups (n = 6–9, for each lime point in each group): gasless group, pneumoperitoneum group, laparotomy group, and control group. The surgical treatment groups received additional cecal resection at the end of the procedures. Spleen cells and hepatic nonparenchymal cells were harvested at 6, 24, or 96 h, to determine the splenic and hepatic NK activities against YAC-1 cells. Results: Compared with the anesthesia control, laparotomy and pneumoperitoneum depressed splenic NK activity at 24 h (p < 0.01 for laparotomy and p < 0.05, for pneumoperitoneum) and 96 h (p < 0.05). Laparotomy also depressed hepatic NK activity at 24 h (p < 0.05). In contrast, the gasless procedure did not show any deterioration in the splenic and hepatic NK activities. Conclusion: These results suggest that gasless laparoscopic surgery would be a favorable approach in terms of the preservation of NK activities.     

CO<Subscript>2</Subscript> lasers thermal changes on laryngeal tissue after different application modes

Summary Standardized operations including incisions and ablations were carried out on pigthroats immediately prior to evaluation of the depths of thermal damage zones measured with a unit of 30 mikrons. The following parameters were applied on the tissue: 1) Continuous versus single pulse mode. 2) equal energy impacts with variation of time and power density. 3) super pulse versus non super pulse.In the 1st series the tissue damage for all tissues examined were significantly lower in the single pulse mode than in the continuous mode. In the 2nd series the pooled material showed a significance in favour of short impacts with high power density although the total energy required for a single operation was up to 40% higher in the high power/short time series. The 3rd series showed no significance in differences between super pulse and nonsuper pulse damage when applying the same average output on the laryngeal tissues involved.