Carbon dioxide suppresses macrophage superoxide anion production independent of extracellular pH and mitochondrial activity.

BACKGROUND: Superoxide anions released by activated macrophages during surgery are considered to be responsible for local cellular damage. Application of CO2 pneumoperitoneum during laparoscopy affects superoxide anion release, but the underlying mechanism remains unclear and the data reported are conflicting. We investigated the direct and pH-mediated impact of CO2 and air on macrophage superoxide anion production. METHODS: Cells of the NR 8383 rat macrophage cell line were incubated for 2 hours in 5% CO2, 100% CO2, and room air or pH 7.4, pH 6.5, and pH 5.5. The extracellular pH was monitored during incubation. At 0, 2, and 6 hours after incubation, the release of superoxide anions was determined fluorometrically. The mitochondrial activity was determined via the conversion of MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] during and after incubation. RESULTS: Extracellular pH decreased to 6.4 during incubation in a CO2 atmosphere. The release of superoxide anions was significantly reduced immediately after CO2 incubation. It was restored at all other time-points. Decreasing the extracellular pH to 6.5 had no effect on superoxide anion release, whereas acidification of the extracellular milieu to pH 5.5 significantly suppressed subsequent superoxide release. Mitochondrial activity was significantly decreased by CO2 up to 2 hours and by acidic milieu up to 6 hours. Incubation in room air had no effect. CONCLUSIONS: Incubation in CO2 can directly suppress macrophage superoxide anion production. This effect is of short duration, fully reversible, and not correlated to changes in extracellular pH or mitochondrial activity. Air contamination does not affect macrophage superoxide anion release. We speculate that CO2 pneumoperitoneum could attenuate the intraoperative free radical production by directly inhibiting superoxide anion release of macrophages without long-lasting suppression of macrophages and their capacity to release superoxide anions postoperatively.

Hemodynamic changes during acute elevation of intra-abdominal pressure in rabbits.

BACKGROUND: The intra-abdominal pressure (IAP) may be increased during pneumoperitoneum for minimally invasive surgery, after high tension repairs of congenital abdominal wall defects, major abdominal surgery, liver transplantation, abdominal trauma, peritonitis or ileus. The aim of this study was to investigate hemodynamic changes during elevation of IAP using an experimental setting, which mirrors anatomical and physiological conditions of neonates and small infants as closely as possible. METHODS: In five fasted, anesthetized, mechanically ventilated and multicatheterized New Zealand rabbits, the IAP was gradually increased by intra-abdominal infusion of normal saline (total volume 1000 ml). At baseline and after each infusion of 100 ml normal saline cardiac output (CO, transcardiopulmonary thermodilution), pressure in the superior (SVCP) and inferior vena cava (IVCP), mean arterial pressure (MAP), peak airway pressure (PAP) and IAP was recorded. RESULTS: During the study, IAP, SVCP and IVCP increased significantly. IVCP was significantly higher than SVCP from timepoint 200 ml to study end. After abdominal decompression IAP, SVCP and IVCP decreased to baseline levels. Changes in MAP were not significant. CO increased significantly from baseline to timepoint 200 ml (peak value), remained nearly constant until timepoint 800 ml and decreased thereafter until the abdominal infusion ceased. After abdominal decompression CO returned to baseline level. SVCP, IVCP and PAP correlated significantly with IAP (SVCP, r = 0.73; IVCP, r = 0.97; PAP, r = 0.94; P < 0.0001). CONCLUSIONS: The hemodynamic changes caused by increased IAP cannot be recognized by routine monitoring of arterial blood pressure and transcutaneous oxygen saturation. The increase in central venous pressure may be misinterpreted as an elevation of cardiac preload. One major effect of a prolonged increase in IAP is a decreased CO.

Laparoscopy vs minilaparotomy and full laparotomy preserves circulatory but not peritoneal and pulmonary immune responses.

PURPOSE: Laparoscopy has been associated with lower inflammatory responses. However, it has been postulated that minilaparotomy, in contrast to full laparotomy, is equally minimally invasive. OBJECTIVE: The aim of this study was to investigate local, systemic, and distant organ immune responses after different surgical approaches to the abdominal cavity, such as minilaparotomy, full laparotomy, and laparoscopy, in a small animal model. METHODS: Male Lewis rats received a permanent central venous catheter and were randomized to 4 groups (n = 6 per group). The animals were subjected to anesthesia alone (control), minilaparotomy (1 cm), full laparotomy (7 cm), or laparoscopy for 60 minutes. Blood was collected via the central venous catheter before as well as 1 hour and 6 hours after the start of intervention. Peritoneal and bronchoalveolar lavages, as well as heart puncture, were performed after 24 hours. RESULTS: All surgical interventions led to a significant migration of polymorphonucleocytes into the abdominal cavity. Full laparotomy resulted in a significant increase in nitric oxide production by peritoneal macrophages as compared with control. Macrophage nitric oxide production after laparoscopy and minilaparotomy was not significantly different. A shift in the expression of OX-6 and CD54 was only detected after full laparotomy. Systemically, O(2)(-) release by circulating mononuclear cells was significantly increased after minilaparotomy and full laparotomy, but not after laparoscopy. The systemic levels of IL6 were significantly accelerated only after full laparotomy, with a maximum after 6 hours. In the lungs, function of alveolar macrophages was not altered in any group. CONCLUSIONS: Any approach to the peritoneal cavity causes local inflammatory responses. Full laparotomy alters peritoneal macrophage functions more pronouncedly than does minilaparotomy or laparoscopy. Systemic inflammatory responses, such as free oxygen radical release, are significantly increased by both minilaparotomy and full laparotomy, whereas laparoscopy preserves systemic immune function. Our results may lead to further preference for the laparoscopic approach over minilaparotomy and full laparotomy.

Laparoscopic repair of neonatal gastric perforation.

BACKGROUND: Gastric perforation is a rare, life-threatening condition in neonates. To avoid deterioration, prompt surgical treatment is mandatory. PATIENTS: We report on 2 neonates (1 and 8 days old) with feeding tube associated gastric perforation managed laparoscopically by single layer suture repair. Both children suffered from severe peritonitis. Operative time was 60 minutes in both cases. Oral feeding was started on postoperative day 3 and 7, respectively. No complications regarding the gastric perforation were encountered on follow-up (11 and 8 months, respectively) in both cases. CONCLUSIONS: We recommend laparoscopic suture repair as a safe and feasible method for surgical treatment of gastric perforation in neonates. These appear to be the first reported cases using this procedure for treatment of neonatal gastric perforation.

Thoracoscopic resection of intra- and extralobar pulmonary sequestration in the first 3 months of life.

BACKGROUND: Thoracoscopic techniques have gained increasing acceptance in pediatric surgery, but experience with newborns and small children is limited. To our knowledge, a series of minimally invasive resection of pulmonary sequestration in newborns has not yet been reported in the literature. We report on 5 patients with pulmonary sequestration thoracoscopically. METHODS: From November 2000 to November 2002, 5 patients underwent thoracoscopic resection of pulmonary sequestration. Ages ranged from 4 to 91 days. Two patients had postnatal pulmonary symptoms. Preoperative diagnosis was dubious in 4 children. There were 4 extralobar and 1 intralobar pulmonary sequestrations. RESULTS: Thoracoscopy was performed with 3-mm instruments and 3 to 5 ports. All procedures were completed successfully. The median duration of the operation was 95 minutes (range, 63-117 minutes), and visualization was excellent. Anomalous blood vessels were clipped and/or ligated. Four patients were extubated immediately after the operation, 1, the day after. The postoperative course was uneventful in all children. At follow-up after 14 months (mean; range, 10-19 months), all patients were free of symptoms and had normal chest x-rays. CONCLUSION: Thoracoscopy is feasible for resection of intra- and extralobar pulmonary sequestrations during the first 3 months of life.

Surgical repair of combined gastroschisis and sternal cleft.

We present a case of prenatally diagnosed gastroschisis combined with a sternal cleft, as well as the successful surgical management of this unusual condition. Successful management of gastroschisis combined with sternal cleft has not been reported before in the literature.

Laparoscopically assisted gastric pull-up for long gap esophageal atresia.

BACKGROUND: Laparoscopically assisted gastric pull-up procedure has been performed in adults for various conditions. The authors report the first patient, who underwent laparoscopically assisted esophageal replacement for long gap esophageal atresia. METHODS: The patient had Down's syndrome and long gap esophageal atresia without fistula. A gastrostomy was performed right after birth, and a suction drain was positioned in the upper esophageal pouch. Esophageal replacement took place at the age of 3 months. The laparoscopic operation included complete mobilization of the stomach, resection of the lower esophageal stump (Endo-GIA), pyloroplasty, and transhiatal dissection. After a right cervical approach, the gastric pull-up was performed through the posterior mediastinum, and the upper anastomosis was completed. Finally, a laparoscopic jejunostomy was performed. RESULTS: The duration of the operation was 4.5 hours. The intra- and postoperative courses were uneventful. Feeding via the jejunostomy was started on day 1. Gastric emptying of contrast media was documented by x-ray examination. Oral feeding was started on day 8 and is now, 3 months postoperative, well tolerated. CONCLUSIONS: This is the first report on laparoscopically assisted gastric pull-up for long gap esophageal atresia. The technique represents an option for the treatment of long gap esophageal atresia.