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Colon adenocarcinoma and B-16 melanoma grow larger following laparotomy vs. pneumoperitoneum in a murine model.

PURPOSE: Mouse mammary carcinoma tumors are established more easily and grow larger after sham laparotomy and open bowel resection than after CO2 pneumoperitoneum and laparoscopic-assisted bowel resection. The purpose of this study was to determine whether similar differences in tumor growth would be found when sham laparotomy and pneumoperitoneum were compared for the colon-26 mouse adenocarcinoma and B-16 mouse melanoma tumor lines. METHODS: In all three studies, a high-dose injection of tumor cells was used, which resulted in tumors in almost all control mice. In Study 1, female BALB/C mice (n = 127) were injected intradermally in the dorsal skin with 10(6) colon-26 cells in a 0.1-ml volume before interventions. In Study 2, female C57 BL/6 mice (n = 140) were inoculated similarly with 10(6) B-16 melanoma cells. Study 2 consisted of three separate trials conducted on different days. Study 3 was performed because considerable differences in mean tumor size were observed in each of these trials. In Study 3, the B16 experiment was repeated with a larger n (n = 82) on a single day. In each study, after tumor cell injections, mice were randomly assigned to one of three groups: 1) anesthesia control (no procedure); 2) full laparotomy (4-cm midline incision x 20 minutes, staple closure); or 3) CO2 pneumoperitoneum (4-6 mmHg X 20 minutes). Tumors were excised and weighed on postoperative day 12. RESULTS: In Studies 1 and 3, mean tumor sizes of the laparotomy groups were significantly larger than both the control group and pneumoperitoneum group lesions (P values by Student's t-test). In Study 2, laparotomy group tumors, although significantly larger than control group lesions, were not significantly larger than pneumoperitoneum group tumors. For all three studies, there was no significant difference between mean tumor sizes of the pneumoperitoneum and control groups. CONCLUSION: Both colon-26 adenocarcinoma and B-16 melanoma tumors grow larger after laparotomy than after pneumoperitoneum in a murine model. The mechanism of these postoperative tumor growth differences remains to be elucidated.

Adenocarcinoma↗

Modulation of renal sympathetic nerve activity during pneumoperitoneum in rats.

To examine neural control of renal function during pneumoperitoneum, renal sympathetic nerve activity (RSNA) was measured in pentobarbital-anesthetized rats that had their entire nervous system intact or that had undergone lower thoracic dorsal rhizotomy or abdominal vagotomy. During pneumoperitoneum with intraabdominal pressure (IAP) of 10 mmHg, the mean arterial pressure did not change, but central venous pressure increased by 10 mmHg in all groups. In intact rats, the RSNA increased to 285 +/- 22% during pneumoperitoneum and gradually recovered after release of the insufflation. The RSNA responses decreased during pneumoperitoneum in rats with dorsal rhizotomy or vagotomy compared to responses in intact rats. In intact rats the urine volume and Na+ excretion decreased during pneumoperitoneum and increased just after insufflation release. Dorsal rhizotomy, vagotomy, or renal denervation did not alter the antidiuretic and antinatriuretic responses during pneumoperitoneum; however, diuretic and natriuretic responses were completely abolished by either of these denervations following insufflation release. These results suggest that oliguria during pneumoperitoneum was not due to neural control of renal function but probably to a mechanical influence induced by the elevated IAP. On the other hand, diuretic and natriuretic responses after insufflation release were thought to be a neurally mediated response.

Analysis of Variance↗

Combined low pressure pneumoperitoneum and intraperitoneal infusion of normal saline for reducing shoulder tip pain following laparoscopic cholecystectomy.

INTRODUCTION: Intraabdominal CO(2) gas after laparoscopic cholecystectomy causes postoperative shoulder-tip pain. Many methods of analgesia have been used to reduce this pain, including analgesic drugs, intraperitoneal local anesthetic, intraperitoneal saline, a gas drain, heated gas, low-pressure gas, and nitrous oxide pneumoperitoneum. The aim of this study was to evaluate the efficacy of combined low-pressure CO(2) pneumoperitoneum and intraperitoneal infusion of normal saline in reducing the incidence of postoperative shoulder-tip pain. METHODS: Altogether, 109 patients undergoing elective laparoscopic cholecystectomy were randomized prospectively into three groups. Patients in group A (n = 34) underwent laparoscopic cholecystectomy with 14 mmHg CO(2) pneumoperitoneum; patients in group B (n = 37) underwent laparoscopic cholecystectomy with 10 mmHg CO(2) pneumoperitoneum; and those in group C (n = 38) underwent laparoscopic cholecystectomy with 10 mmHg CO(2) pneumoperitoneum in addition to intraperitoneal normal saline infusion in the right hemidiaphragmatic area. Shoulder-tip pain was recorded on a verbal rating scale 2, 6, 12, 24, and 48 hours after operation. RESULTS: Twelve patients in group A (35.2 percent), six in group B (16.2 percent), and seven in group C (18.4 percent) complained of shoulder-tip pain. Hence, there was a significant decrease in the frequency of shoulder-tip pain in groups B and C in relation to group A, but there was no significant difference between groups B and C. The postoperative shoulder-tip pain scores were significantly reduced in group C at 6, 12, and 24 hours. The number of patients who required additional analgesics was also reduced in group C. CONCLUSIONS: Low-pressure CO(2) pneumoperitoneum reduces the number of patients complaining of shoulder-tip pain and the intensity of the pain after laparoscopic cholecystectomy. The addition of intraperitoneal normal saline infusion to low-pressure CO(2) pneumoperitoneum seems to reduce the intensity but not the frequency of shoulder-tip pain after laparoscopic cholecystectomy.

Adult↗

Liver metastasis and ICAM-1 mRNA expression in the liver after carbon dioxide pneumoperitoneum in a murine model.

BACKGROUND: Liver metastasis of colorectal malignancies is an important prognostic factor. Several studies have demonstrated that carbon dioxide (CO2) pneumoperitoneum enhances liver metastasis in animal models. Little is known about intercellular adhesion molecule-1 (ICAM-1) and tumor necrosis factor-alpha (TNF-(alpha) mRNA expression in the liver after CO2 pneumoperitoneum. METHODS: Forty-five male BALB/c mice were randomly divided into three groups after intra-splenic tumor cell (colon 26) inoculation and the following procedures were performed: CO2 pneumoperitoneum (n = 15), open laparotomy (n = 15), and anesthesia alone (n = 15). On day 7 after each procedure, the livers were excised and the number and diameter of the tumor nodules and the cancer index score were determined. Another 90 male BALB/c mice were randomly divided into three groups as described above, and they underwent each procedure (n = 30 each). After each procedure, the livers were excised on days 0, 1, 3, and ICAM-1 and TNF-alpha mRNA expression were examined by real-time RT-PCR using SYBR Green I. RESULTS: The number of tumor nodules and the cancer index score were larger in the CO2 pneumoperitoneum group than in the control group (p < 0.05). The mean diameter of the tumor nodules was not different among the three groups. The expression of ICAM-1 in the CO2 pneumoperitoneum group was higher than that in the other groups on day 1 (p < 0.05), and the TNF-alpha mRNA was higher than that in the control group on day 1 (p < 0.05). CONCLUSIONS: CO2 pneumoperitoneum enhances liver metastasis compared with anesthesia alone, and ICAM-1 expression in the liver after the pneumoperitoneum plays an important role in establishing liver metastasis in a murine model.

Animals↗

Effect of pneumoperitoneum on renal perfusion and function: a systematic review.

BACKGROUND: The precise physiologic consequences of insufflating carbon dioxide into the abdominal cavity during laparoscopy are not yet fully understood. This systematic review aimed to investigate whether pneumoperitoneum results in decreased renal blood flow (RBF) or renal function. METHODS: A literature search was conducted electronically using Medline, Embase, and the Cochrane libraries on 1 July 2005. Various combinations of the medical subject headings--renal blood flow, pneumoperitoneum, renal function, and laparoscopy--were searched in all three databases. Reference lists from articles fulfilling the search criteria were used to identify additional articles. RESULTS: The literature search retrieved 20 articles concerning RBF and 25 articles concerning renal function during pneumoperitoneum. It was found that 17 of the 20 studies identified a decrease in RBF, and 20 of the 25 studies identified a decrease in renal function during pneumoperitoneum. CONCLUSION: There appears to be sufficient evidence to conclude that both renal function and RBF are decreased during pneumoperitoneum. The magnitude of the decrease is dependent on factors such as preoperative renal function, level of hydration, level of pneumoperitoneum, patient positioning, and duration of pneumoperitoneum.

Animals↗

Pneumoperitoneum with carbon dioxide enhances liver metastases of cancer cells implanted into the portal vein in rabbits.

BACKGROUND: Little is known about the role of the CO2 pneumoperitoneum on tumor cells that spread from the portal system into the liver during laparoscopic surgery for gastrointestinal malignancies. Therefore, we designed a study to investigate the effect of CO2 pneumoperitoneum on cancer cells implanted in the portal vein in a rabbit model. METHODS: Immediately after intraportal inoculation of 2.5x10(5) cells of VX2 cancer, the rabbits received either CO2 pneumoperitoneum at a pressure of 10 mm Hg for 30 min (pneumoperitoneum group, n = 14) or laparotomy alone for 30 min (laparotomy group, n = 14). RESULTS: The number (p<0.01) and area of cancer nodules (p = 0.045) on the liver surface on day 17 were greater in the pneumoperitoneum group than in the laparotomy group. The frequency of cancer nodules >3.0 mm in diameter was higher in the pneumoperitoneum group than in the laparotomy group (p<0.001). CONCLUSIONS: Compared with laparotomy, CO2 pneumoperitoneum enhanced the development of liver metastases in this experimental model.

Animals↗

Pneumoperitoneum upregulates preproendothelin-1 messenger RNA.

BACKGROUND: Laparoscopic pneumoperitoneum has been shown to decrease glomerular filtration rate (GFR) and urine volume (UV). Endothelin-1 (ET-1), a potent renal vasoconstrictor, has been implicated. The purpose of this study was to determine renal function, ET-1 gene expression, and peptide localization in kidneys subjected to CO2 pneumoperitoneum. METHODS: Experiments were performed in three groups of anesthetized Sprague-Dawley rats in which GFR and UV were measured before, during, and after insufflation. In the first group (n = 8), pneumoperitoneum (10 mmHg) was established for 30 min. The second group (n = 4) underwent a sham operation without pneumoperitoneum. In the final group (n = 4), kidneys were obtained from normal control animals without any prior surgical instrumentation. PreproET-1 (ppET-1) mRNA levels were measured by reverse transcription-polymerase chain reaction (RT-PCR). The ET-1 peptide was localized within kidneys by immunohistochemistry (IHC). RESULTS: Pneumoperitoneum caused a significant (p < 0.05) 87% decrease in GFR and a 79% decrease in UV from baseline, with a return to baseline values after desufflation. RT-PCR showed a significant (p < 0.05) increase in expression of ppET-1 mRNA in the laparoscopic group; it was 3.52 +/- 0.33 densitometric units (DU), as compared to 0.35 +/- 0.06 DU and 0.57 +/- 0.12 DU in the control and sham groups, respectively. IHC showed enhanced expression of the ET-1 peptide in the vascular endothelium and proximal tubular cells of the laparoscopic group compared to the control and sham groups. CONCLUSION: Pneumoperitoneum induces ET-1 gene and peptide upregulation in the kidney. Expression of ET-1 is increased in the renal vasculature and proximal tubular cells. The elevation of ET-1 and its localization may account for some of the renal dysfunction observed during pneumoperitoneum. This suggests that antagonism of ET-1 may be beneficial in patients with renal impairment undergoing prolonged laparoscopic procedures or in protecting allograft function during and after living donor nephrectomy.

Animals↗

Does pneumoperitoneum during laparoscopy increase bacterial translocation?

BACKGROUND: To evaluate the impact of laparoscopy in the presence of peritonitis, this study was designed to assess bacteremia caused by E. coli-induced peritonitis with a carbon dioxide pneumoperitoneum in a rat model. METHODS: Sixty Sprague-Dawley rats were divided into inoculum groups (no E. coli, 10(6) colony-forming units [CFU] E. coli, and 10(8) CFU E. coli), followed by induction of a carbon dioxide pneumoperitoneum or no pneumoperitoneum. Fifteen-minute-interval blood cultures were obtained to determine time of bacteremia development. Statistical assessment to determine significant differences among groups was done using ANOVA and t-test analysis. RESULTS: A total of 20 animals with E. coli introduced into the peritoneum and a carbon-dioxide-induced pneumoperitoneum had more frequent positive blood cultures at all time intervals compared to identical inoculum subgroups without a pneumoperitoneum. ANOVA revealed a significant difference in bacteremia within the same concentration inoculum groups in animals receiving a pneumoperitoneum vs none (p < 0.01). Bacteremia increased significantly as inoculum concentrations increased (25% with 10(6) E. coli inoculum vs 80% with 10(8) E. coli), especially among the insufflated subgroups (45% with 10(6) E. coli vs 100% with 10(8) E. coli) over 180 min (p < 0.01). CONCLUSION: Carbon dioxide pneumoperitoneum increases the incidence of E. coli bacterial translocation from the peritoneum into the bloodstream in this rat model.

Animals↗

Preoperative progressive pneumoperitoneum in patients with abdominal-wall hernias.

Induction of preoperative progressive pneumoperitoneum is an elective procedure in patients with hernias with loss of domain. A prospective study was carried out from June 2003 to May 2005 at the Hospital de Especialidades, Instituto Mexicano del Seguro Social, Leon, Mexico. Preoperative progressive pneumoperitoneum was induced using a double-lumen intraabdominal catheter inserted through a Veress needle and daily insufflation of ambient air. Variables analyzed were age, sex, body mass index, type, location and size of defective hernia, number of previous repairs, number of days pneumoperitoneum was maintained, type of hernioplasty, and incidence of complications. Of 12 patients, 2 were excluded because it was technically impossible to induce pneumoperitoneum. Of the remaining 10 patients, 60% were female and 40% were male. The patients' average age was 51.5 years, average body mass index was 34.7, and evolution time of their hernias ranged from 8 months to 23 years. Nine patients had ventral hernias and one had an inguinal hernia. Pneumoperitoneum was maintained for an average of 9.3 days and there were no serious complications relating to the puncture or the maintenance of the pneumoperitoneum. One patient who previously had undergone a mastectomy experienced minor complications. We were able to perform hernioplasty on all patients, eight with the Rives technique, one with supra-aponeurotic mesh, and one using the Lichtenstein method for inguinal hernia repair. One patient's wound became infected postoperatively. Preoperative progressive pneumoperitoneum is a safe procedure that is easy to perform and that facilitates surgical hernia repair in patients with hernia with loss of domain. Complications are infrequent, patient tolerability is adequate, and the proposed modification to the puncture technique makes the procedure even safer.

Abdominal Wall↗

True incidence and clinical significance of pneumoperitoneum after PEG placement: a prospective study.

BACKGROUND: PEG is a widely used method for providing nutritional support. Although pneumoperitoneum is a known finding after PEG placement, its true incidence is subject to debate. Small retrospective studies have found varied rates of free air after PEG placement. PATIENTS: There were a total of 65 patients. OBJECTIVE: To assess the true incidence of pneumoperitoneum and its clinical significance. DESIGN: Prospective study. SETTING: Long Island Jewish Medical Center. INTERVENTIONS: We obtained upright and anterior-posterior chest radiographs of 65 patients within 3 hours after PEG placement. Type of PEG tube, gauge of the needle used, number of sticks, and indications were recorded. The presence of pneumoperitoneum on the initial chest film was considered to be a positive finding. After a positive result, a repeat chest film was obtained 72 hours later to determine whether there was progression or resolution of the free air. Patients enrolled in the study were also monitored clinically for evidence of peritonitis. MAIN OUTCOME: Of the 65 patients who underwent PEG placement, 13 developed a pneumoperitoneum on the initial chest radiograph; there was complete resolution of pneumoperitoneum at 72 hours in 10 of the 13 patients. In 3 patients, the free air persisted but was of no clinical significance. MEASUREMENTS: The free air was quantified by measuring the height of the air column under the diaphragm and was graded with a scoring system (0, no air; 1, small; 2, moderate; 3, large). RESULTS: Eleven patients who underwent PEG died during the hospitalization; none of the deaths were related to the PEG placement or pneumoperitoneum. The other 54 patients were discharged to a skilled nursing facility. No patients in the study had clinical evidence of peritonitis. There were no adverse events, ie, infection or bleeding, associated with the PEG placement in any of the patients. CONCLUSIONS: Our data suggest that pneumoperitoneum after PEG placement is common and, in the absence of clinical symptoms, is of no clinical significance and does not warrant any further intervention.

Adult↗

Does CO2 pneumoperitoneum alter the ultra-structuture of the mesothelium?

BACKGROUND: Pneumoperitoneum may be responsible for ultra-structural alterations in the mesothelium during laparoscopy. To characterize the effect of pneumoperitoneum on the mesothelial cells with CO(2) and compressed air; and to compare to laparotomy and control group (anesthesia only). MATERIALS AND METHODS: Forty C-57 mice were divided in four groups of 10 animals each: CO(2), air, laparotomy, and control group. The animals were submitted to pneumoperitoneum at 8 mmHg during 30 min (CO(2) or compressed air). Five animals of each group were sacrificed 2 and 24 h after the procedure. Fragments of parietal peritoneum were collected and processed for scanning electron microscopy. RESULTS: Control group revealed uninterrupted mesothelial cells, without any evidence of cellular limits; close contact between the cells; absence of intercellular clefts and presence of microvilli. In the laparotomy group, similar results to the control group, with decreased microvilli were noted. Air pneumoperitoneum was associated with alterations in the morphology of the mesothelial cells, clear cellular limits, and cells with spherical and fusiforme formats. CO(2) pneumoperitoneum showed mesothelial cells with clear cellular limits, predominantly spherical cellular format, and intercellular clefts that allowed the visualization of the exposed basal membrane. These alterations were more intense after 24 h. There was a statistical significance between CO(2) group (2 and 24 h) compared to the control group and laparotomy for cellular limits, intercellular clefts and microvilli, P < 0.0001. CONCLUSIONS: Pneumoperitoneum causes damage in the mesothelial ultra-structure, which differs from the laparotomy group. CO(2) pneumoperitoneum is more harmful to the mesothelium than the air.

Air↗

Tumor growth and dissemination after laparotomy and CO2 pneumoperitoneum: a rat ovarian cancer model.

OBJECTIVE: To compare tumor growth, intraperitoneal implantation, and abdominal wall metastasis after laparotomy and CO2 pneumoperitoneum in a rat ovarian cancer model. METHODS: To mimic intraoperative rupture of an ovarian tumor in a syngenic rat ovarian carcinoma model, 10(5) malignant cells were injected intraperitoneally after a 5-cm vertical midline laparotomy or after the insufflation of a CO2 pneumoperitoneum achieved with 4 mmHg or 10 mmHg intra-abdominal pressure. Two weeks later, the intraperitoneal tumor growth and the tumor dissemination were evaluated semiquantitatively with a scoring system. The scores attributed to each organ were added to calculate the dissemination score of each animal. RESULTS: The mean (+/-SD) dissemination score was 83.4+/-12 in the laparotomy group and 67.3+/-16 and 71.9+/-17 in the 4 and 10 mmHg CO2 pneumoperitoneum groups, respectively (P < .01). The scores for the peritoneum were 21.8+/-3.8 in the 10 mmHg pneumoperitoneum group and 18+/-2.4 in the laparotomy group (P < .01). In the laparotomy group, the implant found along the midline scar accounted for a mean of 62.6+/-15% of the peritoneal score, whereas the trocar site metastases did not influence the peritoneal score in the pneumoperitoneum groups. The incidence of wound metastasis was 96% in the laparotomy group and 55% and 54% in the 4 mmHg and 10 mmHg pneumoperitoneum groups, respectively. CONCLUSION: In this model, tumor growth was greater after laparotomy than after laparoscopy, but peritoneal tumor dissemination was more severe after CO2 pneumoperitoneum.

Animals↗

Changes in intrathoracic blood volume associated with pneumoperitoneum and positioning.

BACKGROUND: It is still controversial whether elevated cardiac filling pressures after the onset of pneumoperitoneum are the consequence of increased intrathoracic pressure or of increased venous return. The aim of this study was to assess the effects of pneumoperitoneum and body positioning on intrathoracic blood volume (ITBV). METHODS: Thirty anesthetized patients were randomly assigned to have CO2-pneumoperitoneum (13 mmHg) either in a supine, in a 15 degrees head-up tilt or in a 15 degrees head-down tilt position. Measurements of ITBV and hemodynamics by the double indicator method were recorded after induction of anesthesia and application of a fluid bolus (Lactated Ringer's solution 10 ml/kg), after positioning and after induction of pneumoperitoneum. RESULTS: Intrathoracic blood volume index (ITBVI) increased significantly after induction of pneumoperitoneum in all body positions (supine: from 18.5 +/- 3.3 -20.2 +/- 5.2 ml/kg (+6%) head-up from 16.7 +/- 3.8 - 17.4 +/- 3.7 ml/kg (+16%) and head-down: from 19.8 +/- 5.6 - 20.5 +/- 5.9 ml/kg (+14%)). Heart rate did not change significantly in any of the groups. Cardiac index showed a statistically significant change in the head-down position with pneumoperitoneum (-11%). A good correlation was found for stroke volume (SV) with ITBV (r = 0.79), but not with central venous pressure (r = 0.26). Systemic vascular resistance index increased significantly in all three groups (supine +6%, head-up +16%, head-down position +14%). CONCLUSION: The present study indicates that the onset of pneumoperitoneum, even with moderate intra-abdominal pressures, is associated with an increased intrathoracic blood volume in ASA I/II patients.

Adult↗

Spontaneous pneumoperitoneum associated with colonic pseudo-obstruction.

Pneumoperitoneum is almost always pathognomonic of a perforated abdominal viscus requiring urgent surgical intervention. Spontaneous or non-surgical pneumoperitoneum is a rare clinical condition arising secondary to abdominal, thoracic, gynaecologic or idiopathic causes. In addition to good clinical judgement, an important component in the management process is to rule out other causes of pneumoperitoneum by performing appropriate investigations. We describe a 60-year-old man who presented with clinical features of pseudo-obstruction, following an injury to his back which was compounded by hypokalaemia. Roentgenography revealed massive pneumoperitoneum and colonic distension. As there were no overt clinical features of peritonitis, the patient was managed conservatively with parenteral nutrition and close observation. A water-soluble contrast enema and computed tomography of the abdomen were of no help in identifying the cause of his pneumoperitoneum but were helpful in eliminating the presence of hollow viscus perforation or an obvious inflammatory focus. The aetiology of pneumoperitoneum in our patient was most likely due to dissection of air through the distended colonic wall, secondary to large bowel pseudo-obstruction. The diagnosis of spontaneous or non-surgical pneumoperitoneum is one of exclusion and we stress the importance of relying on clinical parameters when managing such patients conservatively.

Colonic Pseudo-Obstruction↗

Increased intra-abdominal pressure during pneumoperitoneum stimulates endothelin release in a canine model.

Prolonged pneumoperitoneum during laparoscopic surgery has been associated with oliguria in clinical experimental studies. Although the pathophysiology of this oliguria is thought to be renal parenchymal and venous compression, the role of the potent vasoconstrictor endothelin (ET) has not been studied. The purpose of this study was to investigate the effect of pneumoperitoneum on endothelin release and renal function in a canine model. Two groups of dogs were studied during pneumoperitoneum (Group 1, N = 7) or isolated left renal vein compression (Group 2, N = 6). Urine and plasma samples were collected for urine output, glomerular filtration rate (GFR), urine sodium, and plasma endothelin measurements. In Group 1, GFR fell significantly (p < 0.05) by 49% from a control of 0.88 +/- 0.12 mL/min per gram of kidney weight. Urine volume fell by 79% (p < 0.05) from a control value of 0.014 +/- 0.003 mL/min/gkw. Sodium excretion was decreased by 88%. Sodium reabsorption was significantly enhanced during pneumoperitoneum (99.56 +/- 0.15% v 98.44 +/- 0.25%). Arterial plasma ET concentrations were elevated by 8% during the first 20 minutes of pneumoperitoneum (30.8 +/- 3.6 v 33.3 +/- 3.4 pg/mL; p < 0.05). In Group 2, left renal vein compression resulted in a 31% decrease (p < 0.05) in GFR in the left kidney and a 25% decrease in the right kidney. Urine volume fell by 67% in the left kidney and 40% in the right. Renal venous ET concentrations also increased after renal vein compression. Although the mechanism by which oliguria occurs during pneumoperitoneum is not fully understood, the ET concentration was elevated. Because ET can decrease RBF, GFR, and sodium excretion, it may contribute to the oliguria observed during long periods of pneumoperitoneum.

Abdomen↗

Chronic effect of pneumoperitoneum on renal histology.

BACKGROUND AND OBJECTIVE: Transient intraoperative oliguria is a constant phenomenon during laparoscopic procedures. Laboratory studies have demonstrated that this effect is secondary to a decrease in renal blood flow caused by the pneumoperitoneum. With the advent of laparoscopic harvest of the kidney for renal transplantation, a concern is that increased intra-abdominal pressure may compound the effect of acute cold and warm renal ischemia during transplantation. Acute transient renal ischemia can produce chronic sclerosing histopathologic changes in native kidneys which are similar to those seen in chronic allograft rejection. The effect of positive-pressure abdominal pneumoperitoneum (15 mm Hg) on native kidneys was examined using a rodent model. The effects on renal function and histologic features were also studied. MATERIALS AND METHODS: Twenty-four Harlan Wistar-Furth rats were divided into four groups: controls, 1-hour pneumoperitoneum-91-day survival, 5-hour pneumoperitoneum-91-day survival, and 5-hour pneumoperitoneum-7-day survival. Control animals underwent placement of the Veress needle and anesthesia but no induction of pneumoperitoneum. At the time of sacrifice, blood was sampled for serum creatinine measurement. Both kidneys were harvested for frozen and permanent section and stained using hematoxylin and eosin. Specimens were graded for inflammatory and ischemic/sclerotic changes in the interstitium, tubules, glomeruli, and vasculature by a renal pathologist using a histologic score (0-3). RESULTS: In all groups, at a sacrifice interval of either 1 week or 3 months, there were no statistical differences in the histologic score, serum creatinine concentration, or renal weight. CONCLUSIONS: In a rodent model, no signs of chronic ischemic histologic changes were detected for a period of 3 months after up to 5 hours of pneumoperitoneum. As well, there was no change in the serum creatinine concentration.

Animals↗

Reduction of CO(2)-pneumoperitoneum-induced metabolic hypoxaemia by the addition of small amounts of O(2) to the CO(2) in a rabbit ventilated model. A preliminary study.

BACKGROUND: CO(2)-pneumoperitoneum used in endoscopic surgery induces system effects by CO(2) absorption. This study investigated the effect of the addition of O(2) to CO(2)-pneumoperitoneum, upon CO(2) absorption. METHODS: The effect of a pneumoperitoneum using 100% CO(2) or 94% CO(2) + 6% O(2) upon arterial blood gases, acid base and O(2) homeostasis was evaluated. In series A suboptimal ventilation and a pneumoperitoneum pressure (PP) of 10 mmHg was used. In series B adequate ventilation and PP of 6 mmHg was used. RESULTS: CO(2)-pneumoperitoneum profoundly affected blood gases and acid base homeostasis i.e. increasing pCO(2), HCO(3)(P < 0.001) and lactate concentrations (P < 0.05) and decreasing pH, actual base excess and standard bicarbonate (P < 0.001), resulting in metabolic hypoxaemia with desaturation, lower pO(2) (P < 0.001) and O(2)Hb (P < 0.05). These effects were more pronounced with higher PP and suboptimal ventilation. CONCLUSION: CO(2)-pneumoperitoneum profoundly affected blood gases and acid base homeostasis resulting in metabolic hypoxaemia. The addition of 6% of O(2) to the CO(2)-pneumoperitoneum prevented these effects to a large extent. If these preliminary data are confirmed in the human, the addition of a few percent of O(2) to CO(2) could become important for endoscopic surgery of long duration, especially in obese patients with limited cardiorespiratory adaptation and steep Trendelenburg.

Animals↗

Pneumoperitoneum in peritoneal dialysis patients: significance of diagnosis by CT.

OBJECTIVE: Pneumoperitoneum diagnosed by plain radiography is often a sign of gastrointestinal perforation and is unusual (0.17%) in patients on continuous ambulatory peritoneal dialysis (CAPD). These patients are prone to bacterial peritonitis, which can have overlapping clinical findings with perforated viscus. Because CT is often used to screen symptomatic CAPD patients, the reliability of pneumoperitoneum as a diagnostic sign is examined. MATERIALS AND METHODS: Records of 433 CAPD patients were examined; of these, 56 patients had had CT while on CAPD (rupture, 6; nonrupture, 50). Plain radiography and CT were examined for free air and fluid. Patients were classified according to the amount of free air detected. RESULTS: Patients with ruptured viscus had pneumoperitoneum in 5 of 6 cases by CT and 4 of 6 by plain radiography. Excluding free air, ruptured viscus could only be diagnosed in 1 of the 6 patients by CT. Patients without rupture had pneumoperitoneum in 15 of 50 cases by CT and 2 of 46 by plain radiography. No instance of pneumoperitoneum was discovered on plain radiography and not CT. CONCLUSION: Pneumoperitoneum was found by CT in 30% of nonrupture CAPD patients, therefore, CT appeared to be more sensitive than plain radiography for its detection. The presence, quantity, and distribution of free air are not helpful in separating perforations from nonperforations. The lack of pneumoperitoneum on CT was found to be a useful but not absolute diagnostic sign to exclude gastrointestinal rupture.

Aged↗