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Loss of physiologic hepatic blood flow control ("hepatic arterial buffer response") during CO2-pneumoperitoneum in the rat.

UNLABELLED: We analyzed whether a compensatory increase of hepatic arterial (HA) flow, known as the "hepatic arterial buffer response" (HABR), may serve for maintenance of liver blood supply during laparoscopy-associated portal venous (PV) flow reduction. We assessed HA and PV flow, as well as hepatic tissue oxygenation (PO2) during CO2-pneumoperitoneum in anesthetized and mechanically ventilated Sprague-Dawley rats (n = 7). Control animals (n = 7) without pneumoperitoneum, but tourniquet-induced PV flow reduction served to demonstrate physiologic HABR. Although stepwise tourniquet-induced reduction of PV flow to 20% of baseline values led to a significant (P < 0.05) increase of HA flow from 4.3 +/- 0.7 mL/min to 9.9 +/- 1.7 mL/min, stepwise intraabdominal pressure-induced decrease of PV flow was paralleled by a linear reduction of HA flow from 2.4 +/- 0.3 mL/min to 1.2 +/- 0.5 mL/min at 18 mm Hg intraabdominal pressure. This loss of HABR was sustained during a subsequent 2 h-period of CO2-pneumoperitoneum contrasting the 2 h of maintenance of HABR in controls. Hepatic tissue PO2 decreased during the 2 h-period of pressure- and tourniquet-induced PV flow reduction by 35% to 51%, respectively. On tourniquet release, all variables regained baseline values, whereas evacuation of the pneumoperitoneum allowed all variables except hepatic PO2 to return to baseline, indicating prolonged tissue hypoxia despite restored total liver blood flow in the Laparoscopic group. Concomitantly, increased liver enzyme activities reflected moderate tissue damage after 2 h of pneumoperitoneum. In conclusion, intraabdominal CO2-insufflation-induced hemodynamic alterations may impair tissue oxygenation and enzyme release, indicating the potential risk for hepatic tissue damage after prolonged periods of laparoscopic interventions. IMPLICATIONS: We investigated the effect of CO2-pneumoperitoneum on liver blood flow, hepatic tissue oxygenation (PO2) and liver enzyme release. CO2-insufflation reduces portal venous flow without a compensatory increase of hepatic arterial flow ("hepatic arterial buffer response"), resulting in reduced hepatic PO2 and increased ratios of serum alanine aminotransferase to serum aspartate aminotransferase.

Alanine Transaminase↗

Effect of carbon dioxide pneumoperitoneum on development of atelectasis during anesthesia, examined by spiral computed tomography.

BACKGROUND: Anesthesia per se results in atelectasis development in the dependent regions of the lungs. The effect of pneumoperitoneum on atelectasis formation is not known. The aim of the current study was to measure by spiral computed tomography the effect of carbon dioxide pneumoperitoneum for laparoscopic surgery on the development of atelectasis, overall lung volume, and regional tissue volumes of gas and tissue. METHODS: Seven patients (American Society of Anesthesiologists physical status I), scheduled to undergo laparoscopic cholecystectomy, were observed. After induction of anesthesia, the patients were mechanically ventilated and positioned supine on the computed tomography table. Tomography of the lungs (10 mm spiral) was performed before and 10 min after induction of carbon dioxide pneumoperitoneum at an intraabdominal pressure of 11-13 mmHg. The Student t test was used for statistical analysis. A P value less than 0.05 was considered significant. RESULTS: Induction of pneumoperitoneum increased the mean atelectasis volume in the dependent lung regions by 66% (range, 11-170%). The overall lung volume and gas as well as tissue volume significantly decreased. Relative to the total lung volume, lung tissue volume increased, while gas volume decreased significantly. Both upper and lower lobes reacted the same way. A cranial displacement of the diaphragm between 1 and 3 cm (mean, 1.9 cm) was registered. CONCLUSION: Pneumoperitoneum at an intraabdominal pressure level of 11-13 mmHg increased the volume of atelectasis. Because lung tissue volume increased in the lung, there may have been an opening of previously closed vessels, which could explain previously seen increase in arterial oxygenation after induction of pneumoperitoneum.

Adult↗

Postoperative pneumoperitoneum: an unusual etiology.

Although postoperative pneumoperitoneum is a common finding, it is particularly disturbing when there is an increase in the amount of postoperative pneumoperitoneum or when the radiographic finding of pneumoperitoneum is accompanied by such physical findings as increased abdominal tenderness, peritoneal signs or paralytic ileus. Four patients operated upon at the Mount Sinai Hospital are presented. All patients underwent abdominal surgery for treatment of some form of inflammatory bowel disease and all were receiving systemic corticosteroids in the postoperative period. Abdominal findings of tenderness, ileus and peritoneal irritation developed shortly after the removal of Penrose drains in the postoperative period. Pneumoperitoneum was confirmed by abdominal roentgenographs. The first patient in this group underwent a laparotomy with essentially negative findings other than a freely open drain tract. The subsequent three patients were managed by close observation and frequent abdominal radiographs. These three patients had contrast roentgenographic studies of the upper gastrointestinal tract to rule out perforation of a peptic ulcer, and in the patient upon whom reservoir ileostomy had been performed, a contrast study of the reservoir was performed. All patients recovered fully with this management and there were no sequelae. The mechanism for the appearance of pneumoperitoneum after removal of drains, particularly when the patient is receiving systemic corticosteroids, is discussed. Emphasis is placed on the need to consider and rule out perforation of a hollow viscus in this situation before accepting drain removal as the sole cause of post-operative pneumoperitoneum.

Abdomen↗

Hemodynamic effects of carbon dioxide pneumoperitoneum during mechanical ventilation and positive end-expiratory pressure.

Laparoscopy is frequently used for diagnosis and treatment of critically ill trauma patients. Its effects on cardiopulmonary performance in the intensive care unit patient population, however, are not well-defined. This study evaluated the effects of positive end-expiratory pressure (PEEP) and carbon dioxide (CO2) pneumoperitoneum on hemodynamic function during mechanical ventilation. Five anesthetized, mechanically ventilated adult swine were monitored with pulmonary artery and arterial catheters at 0, 5, 10, 15, and 20 cm H2O PEEP without, and then with 15 mm Hg CO2 pneumoperitoneum. A hemodynamic profile, analyses of arterial and mixed venous blood gases and mixed venous hemoglobin oxygen saturation values were obtained at each data point. Compared with the non-insufflated group, CO2 pneumoperitoneum significantly increased central venous pressure, mean arterial pressure, mean pulmonary artery pressure, pulmonary vascular resistance index, and stroke index for the range of PEEP levels. With PEEP of 10 cm H2O, hemodynamic changes in non-insufflated animals were not statistically significant, but with CO2 pneumoperitoneum, stroke index and left ventricular stroke work index were decreased at 5 cm H2O PEEP, as was cardiac index at 10 cm PEEP. Pulmonary gas exchange was not affected by CO2 pneumoperitoneum. The results indicate that, in this paradigm, CO2 pneumoperitoneum for laparoscopy increases ventricular afterload and exacerbates the adverse effects of PEEP. These findings could be clinically significant in critically ill patients.

Animals↗

The effect of the pneumoperitoneum on the peritoneal defense mechanisms in diabetic rats.

To investigate the effects of pneumoperitoneum on the peritoneal defense mechanism induced by streptozocin infusion during laparoscopic surgery in diabetic rats and to show the importance of regulation of diabetes for peritoneal defense mechanisms. One hundred twenty-six Sprague-Dawley male rats were allocated into six groups each consisting of 21 rats: group 1, nondiabetic sham laparotomy (control); group 2, nondiabetic pneumoperitoneum (control); group 3, uncontrolled diabetes plus sham laparotomy; group 4, controlled diabetes plus sham laparotomy; group 5, uncontrolled diabetes plus pneumoperitoneum; and group 6, controlled diabetes plus pneumoperitoneum. Diabetes was constituted by intraperitoneal infusion of one dose of 60 mg/kg streptozotocin, and diabetes was regulated (in groups 4 and 6) by subcutaneous injection of 10 IU/kg insulin in the morning and evening after the blood glucose measurements since the fourth day. Peritoneal fluid samples were taken at the zero, second, and sixth hours after sham laparotomy for groups 1, 3, and 4 and after pneumoperitoneum for groups 2, 5, and 6 on the seventh day. Total peritoneal cell count, antibacterial activity of the peritoneal fluid, and types of phagocytic cells in the peritoneal fluid were assessed. Peritoneal cell count was found to be lower in uncontrolled diabetes due to high blood glucose levels (>200 mg/dL), which led to slow migration of phagocytic cells into the peritoneum. Pneumoperitoneum had augmented the effect on phagocytic cell migration to the peritoneum compared with the sham laparotomy in controlled diabetic rats. Uncontrolled and controlled diabetes have adverse effects on peritoneal defense mechanism killing functions by interfering with the antimicrobial activity of peritoneal fluid.

Animals↗

Intrathoracic and pulmonary blood volume during CO2-pneumoperitoneum in humans.

BACKGROUND: Induction of CO2-pneumoperitoneum may have significant effects on systemic and pulmonary haemodynamics. We hypothesized that intrathoracic (ITBV) and pulmonary blood volume (PBV) are affected during intra-abdominal CO2-insufflation, which may be pronounced by positional changes of the patient. METHODS: Sixteen anaesthetized patients were studied before, during and after CO2-pneumoperitoneum for laparoscopic cholecystectomy. A dye indicator technique was used to assess ITBV and PBV. In addition, gas exchange and haemodynamics were recorded. RESULTS: In the supine position, induction of CO2-pneumoperitoneum had no effects on ITBV, PBV and cardiac output. Mean systemic arterial pressure increased from 10.9 +/- 1.5 kPa (82 +/- 11 mmHg) to 12.7 +/- 1.5 kPa (95 +/- 11 mmHg, P < 0.01). In the reverse Trendelenburg position ITBV decreased from 19.8 +/- 5.1 ml.kg-1 to 16.7 +/- 3.7 ml.kg-1 (P < 0.05) during CO2-insufflation, but increased to control values after 20 min. PBV decreased from 4.2 +/- 1.2 ml.kg-1 to 3.4 +/- 1.1 ml.kg (P < 0.05) and remained decreased during CO2-pneumoperitoneum. Calculated venous admixture was unchanged throughout the study. Deflation of CO2-pneumoperitoneum increased ITBV (22.4 +/- 5.2 ml.kg-1, P < 0.05) and cardiac output above control values. CONCLUSIONS: In anaesthetized-paralyzed patients in the reverse Trendelenburg position intra-abdominal CO2-insufflation is associated with significant alterations of ITBV and PBV. The release of CO2-pneumoperitoneum is associated with a re-distribution of blood into the thorax.

Abdomen↗

Selective use of ultrasonography for the detection of pneumoperitoneum.

OBJECTIVE: Whether ultrasonography is superior to plain radiography for the detection of pneumoperitoneum is unknown. The goal of this study was to determine the value of ultrasonography for the detection of pneumoperitoneum. METHODS: One hundred thirty-two patients with suspected hollow-organ perforation were prospectively selected for study. All 132 patients received ultrasonography, upright chest radiography, and left lateral decubitus abdominal radiography examinations. The diagnostic accuracies of chest and abdominal radiographs for the detection of pneumoperitoneum were compared with corresponding values from ultrasonography. RESULTS: Of the 125 patients who underwent laparotomy, 121 patients had hollow-organ perforation, three patients had perforated appendicitis, and one patient had acute cholecystitis. For the diagnosis of pneumoperitoneum, ultrasonography demonstrated a sensitivity of 93%, a specificity of 64%, a positive predictive value of 97%, a negative predictive value of 44%, and an accuracy of 90%. Plain radiography revealed a sensitivity of 79%, a specificity of 64%, a positive predictive value of 96%, a negative predictive value of 21%, and an accuracy of 77%. CONCLUSIONS: Ultrasonography is a more sensitive diagnosing modality than plain radiography for the diagnosis of pneumoperitoneum. The authors suggest that ultrasonography was a useful diagnostic modality when plain radiographs failed to reveal pneumoperitoneum among patients with suspected hollow-organ perforation.

Adolescent↗

Influence of CO2 pneumoperitoneum on intracellular pH and signal transduction in cancer cells.

OBJECT: The authors studied the influence of CO(2) pneumoperitoneum on intracellular pH and signal transduction arising from cancer cell multiplication in laparoscopic tumor operation. METHOD: They set up a simulation of pneumoperitoneum under different CO(2) pressure, and then measured the variation of intracellular pH (pHi) at different time and the activity of protein kinase C (PKC) and protein phosphatase 2a (PP2a) at the end of the pneumoperitoneum. After 1 week, the concentration of cancer cells in the culture medium was calculated. RESULT: When the pressure of CO(2) pneumoperitoneum was 0, 10, 20, 30 mmHg respectively, the average pHi was 7.273, 7.075, 6.783, 6.693 at the end of the pneumoperitoneum; PKC activity was 159.4, 168.5, 178.0, 181.6 nmol/(g.min) and PP2a was 4158.3, 4066.9, 3984.0, 3878.5 nmol/(g.min) respectively. After 1 week, the cancer cells concentration was 2.15 x 10(5), 2.03 x 10(5), 2.20 x 10(5), 2.18 x 10(5) L(-1). CONCLUSION: CO(2) pneumoperitoneum could promote acidosis in cancer cells, inducing the activation of protein kinase C and deactivation of protein phosphatase 2a, but it could not accelerate the mitosis rate of the cancer cells.

Animals↗

Detection of pneumoperitoneum on chest radiographs: comparison of upright lateral and posteroanterior projections.

OBJECTIVE: This study was done to determine whether upright lateral chest radiographs were more sensitive than upright posteroanterior chest radiographs in detecting pneumoperitoneum. SUBJECTS AND METHODS: We prospectively evaluated the ability of upright posteroanterior and lateral chest radiographs to show subdiaphragmatic air in 100 consecutive patients with known pneumoperitoneum from a variety of causes. The difference in sensitivity between the two was evaluated by means of McNemar's test. RESULTS: The upright lateral chest radiograph showed pneumoperitoneum in 98% of the cases; the upright posteroanterior chest radiograph showed pneumoperitoneum in only 80%. The upright lateral chest radiograph was significantly better at showing pneumoperitoneum than was the upright posteroanterior chest radiograph (p < .01). CONCLUSION: The upright lateral chest radiograph is more sensitive than the upright posteroanterior chest radiograph in detecting small amounts of pneumoperitoneum. When there is a strong clinical suspicion of a perforated hollow viscus, it may be of benefit to include an erect lateral chest radiograph as part of the acute abdominal series.

Humans↗

Benign pneumoperitoneum after colonoscopy: a prospective pilot study.

Benign pneumoperitoneum is asymptomatic free intraabdominal air and is reported to occur occasionally with colonoscopy. Management of benign pneumoperitoneum after colonoscopy is controversial and may depend on incidence or etiology. No previous studies prospectively investigated the incidence or inciting factors of benign pneumoperitoneum resulting from colonoscopy. In this study, 100 patients underwent colonoscopy and then radiography of the chest and abdomen to detect free air. The average age was 58 +/- 6.2 years, and 48 of the colonoscopies were therapeutic. No cases of benign pneumoperitoneum were detected, estimating the incidence at 0% to 3% for diagnostic and therapeutic colonoscopy. These data indicate that benign pneumoperitoneum attributable to colonoscopy is rare and possibly nonexistent. Given the paucity of data favoring the occurrence of benign pneumoperitoneum after colonoscopy, we advocate treating all cases of free intraabdominal air after colonoscopy as perforations.

Colonoscopy↗

[Effect of pneumoperitoneum on the liver blood flow in cirrhotic rats].

OBJECTIVE: To determine the effect of pneumoperitoneum on liver indocyanine green (ICG) metabolism and the hepatic blood flow in normal and cirrhotic rats. METHODS: Thirty male Wistar rats were randomized into five groups: normal anaesthesia group, normal laparotomy group, normal pneumoperitoneum group, cirrhosis + anaesthesia group, and cirrhosis + pneumoperitoneum group. Liver cirrhosis was induced in two groups by injecting carbon tetrachloride subcutaneously plus drinking 5% alcohol. ICG clearance tests were performed in all the rats. RESULTS: The ICG level in the normal laparotomy group (0.662 micro g/ml) was higher than that in the normal anesthesia group (0.645 micro g/ml), but the difference was not significant (P > 0,05). The ICG level in the normal pneumoperitoneum group (0.967 micro g/ml) was significantly higher than that in the normal anesthesia and normal laparotomy groups (P < 0.05). The ICG levels in two cirrhotic groups were significantly higher than those in the other three groups (P < 0.05). The ICG level in the cirrhosis + pneumoperitoneum (1.348 micro g/ml) was significantly higher than that in the cirrhosis + anesthesia group (1.198 micro g/ml) (P < 0.05). CONCLUSIONS: During laparoscopic surgery, pneumoperitoneum could decrease the liver ICG clearance rate and the hepatic blood flow, which are of clinical significance in determining the state of liver cirrhotic.

Animals↗

[Comparison of electrocardiographic parameters during pneumoperitoneum in patients without cardiovascular diseases and in patients with ischemic heart disease].

UNLABELLED: Pneumoperitoneum induces significant pathophysiological changes. Changes in performance of cardiovascular system can be severe in patients with compromised cardiac function. Groups of patients to whom these changes may be deleterious are yet to be identified. Aim of the study was to elucidate the influence of pneumoperitoneum on the electrocardiographic recording. PATIENTS AND METHODS: 35 cardiovascular healthy (ASA I-II) patients (group 1) and 34 patients with underlying moderate ischemic heart disease (ASA II-IV, Goldman's cardiac risk class II-III) (group 2), scheduled for elective laparoscopic cholecystectomy, were included in the study. Premedication included sedatives for all patients and the group 2 received their usual cardiovascular treatment one hour before operation. A standardized protocol of monitoring and anesthesia was followed in the operating room. 12 lead electrocardiograms (ECG) were obtained before and after induction of anesthesia, every 10 minutes during pneumoperitoneum, after the peritoneal desufflation and after extubation. The ECGs were recorded and analysed by the means of computerized system for ECG record and analysis "Kaunas" (UAB "Kardiosignalas", Kaunas, Lithuania). The analysis was performed postoperatively. RESULTS: During pneumoperitoneum a deviation of cardiac electrical axis to the left was observed. There were no marked changes in duration of P wave, P-Q interval, and QRS complex. Following abdominal insufflation a tendency to flattening of T wave was observed returning to the initial position after desufflation. No significant dislocation of ST segment was recorded. CONCLUSIONS: The pneumoperitoneum induced changes of cardiac electrical axis can affect the interpretation of ECG seen on a cardiac monitor during anesthesia. Pneumoperitoneum does not pose patients with moderate ischemic heart disease at additional risk of developing myocardial ischemia.

Anesthesia, Endotracheal↗

Influence of different pressures of pneumoperitoneum on the autonomic system function during laparoscopy.

UNLABELLED: The effects of different pressure values of pneumoperitoneum on the activity of the autonomic nervous system (ANS) have not been investigated in detail. In this prospective study, 20 patients qualified for laparoscopic cholecystectomy were randomised to either low-pressure (LP = 7 mmHg) or standard-pressure (SP = 12 mmHg) pneumoperitoneum groups, 10 patients each. The anesthesia was induced with fentanyl and thiopental and maintained with isoflurane. Ventilation was mechanically controlled (18 breaths per minute, end-tidal CO2 30-35 mmHg, instant capnometer monitoring). Intraabdominal pressure was maintained automatically by a CO2 insufflator. Patient were kept in a horizontal position. The ANS was evaluated by heart rate variability (HRV) analysis (POSTER ECG 2002 System) measured intraoperatively in three recordings of 5 minutes each: in awake patient, after induction of general anesthesia, and after creation of pneumoperitoneum. Power spectral analysis of HRV was applied, the low-frequency (LF = 0.05-0.15 Hz) and high frequency (HF = 0.15-0.45 Hz) spectral density of the HRV were analysed using the Fast Fourier Transform algorithm. The appropriate statistical analysis of data was performed. LF density decreased at the anesthetized stage and increased at the insufflated stage in both groups (p < 0.01). LP resulted in lower sympathetic activation than SP pneumoperitoneum (LF: 68.12 +/- 6.56 nu vs. 78.26 +/- 5.43 nu, p < 0.01; HF: 24 +/- 2.48 nu vs. 15.56 +/- 2.54 nu, p < 0.05). IN CONCLUSION: pneumoperitoneum leads to sympathetic activation of the ANS. LP in comparison to SP pneumoperitoneum with carbon dioxide results in significantly decreased sympathetic activation during laparoscopy.

Adult↗

[Pneumoperitoneum: is exploratory laparotomy always indicated?].

Pneumoperitoneum usually indicates a surgical emergency because of visceral perforation in 85 to 95% of cases. Spontaneous pneumoperitoneum without peritonitis is a rare phenomenon which poses a dilemma for the surgeon who is faced with this problem. Some cases of pneumoperitoneum can and should be managed conservatively. We report three cases of pneumoperitoneum and describe their outcomes. Two cases were treated conservatively, and one underwent laparotomy but no perforated viscus was found. We review the aetiological mechanisms and the pathophysiology of the appearance of intra-abdominal free gas. Furthermore, a compilation of other aetiologies of pneumoperitoneum without peritonitis as reported in the literature is presented. Pneumoperitoneum, preceded by a reasonable clinical history in a patient with an adequate abdominal examination, may warrant continued observation, thus avoiding an unnecessary laparotomy.

Aged↗

[Pneumoperitoneum without perforation of the gastrointestinal tract in a patient with systemic lupus erythematosus].

Pneumoperitoneum often occurs after the perforation of the gastrointestinal tract. However, pneumoperitoneum without the perforation has been reported as one of the complications of collagen diseases, the cause of which is usually the rupture of pneumatosis cystoides intestinalis (PCI). PCI is sometimes observed in the patients with scleroderma and mixed connective tissue disease but rarely in the patients with systemic lupus erythematosus. We reported here a case of systemic lupus erythematosus developed the pneumoperitoneum without the perforation of gastrointestinal tract. A 51-year-old female who had been diagnosed as systemic lupus erythematosus and taken steroid for 12 years, visited our hospital because of general malaise. She had no abdominal symptoms but the roentgenographic examinations revealed the pneumoperitoneum. The laparotomy was performed and there were no findings of the perforation of the gastrointestinal tract. Because PCI is hardly recognized macroscopically after the rupture and the pneumoperitoneum due to PCI is often asymptomatic, we considered the cause of the pneumoperitoneum in this case was the rupture of PCI. The mechanisms of the formation of PCI in patients with collagen diseases were also discussed in this paper.

Female↗

Spontaneous pneumoperitoneum. A surgical dilemma.

Pneumoperitoneum is usually the result of hollow viscus perforation with associated peritonitis. Nonsurgical spontaneous pneumoperitoneum incidental to intrathoracic, intra-abdominal, gynecologic, iatrogenic, and other miscellaneous causes not associated with perforated viscus have been documented in the literature. Seven cases of spontaneous pneumoperitoneum admitted over 3-year period to Grady Memorial Hospital, Atlanta, Georgia are reported. Six patients with pneumoperitoneum underwent exploratory laparotomy when clinical examination suggested an acute abdomen; no intra-abdominal pathology was documented in any of these patients. A seventh patient, on ventilatory support, was managed conservatively after performing a diagnostic peritoneal lavage that was negative. There were no cases of radiographically misdiagnosed pneumoperitoneum. Pneumoperitoneum, preceded by a reasonable incidental cause in a patient with a adequate abdominal examination, may warrant continued observation thus avoiding an unnecessary laparotomy.

Adult↗

Pneumoperitoneum in the newborn infant.

Fifty-three newborns with pneumoperitoneum were treated between July 1980 and July 1985. The birth weights of these infants ranged from 600 to 4350 grams; nearly 75 per cent weighed less than 1500 grams. The etiology of the pneumoperitoneum and the hospital survival were reviewed. All operative patients had exploratory surgery through an upper abdominal transverse incision extending across both rectus muscles. All gastric and duodenal perforations were closed primarily; the perforations in the remaining gastrointestinal tract were generally exteriorized through the lateral edge of the wound. The single leading cause of pneumoperitoneum in the newborn is necrotizing enterocolitis, accounting for 60 per cent of the patients in this series; 78 per cent of these infants survived. All infants with ("spontaneous") ileal perforations survived. The two patients with colon perforations (from meconium plug obstruction) died, one of congenital heart disease associated with Down's syndrome and the other of hyaline membrane disease. One patient who had mild hyaline membrane disease, who was not ventilated, and who did not have mediastinal emphysema also had pneumoperitoneum for which no cause was found at laparotomy ("spontaneous"). He survived. In six critically ill infants (11% of the series) pneumoperitoneum developed secondary to mediastinal dissection of air from ventilators. None of these infants was operated on because an intestinal perforation as a source of the pneumoperitoneum could reliably be excluded by the presence of pneumomediastinum and/or a negative paracentesis. This group of infants warrants special attention, because in them "negative" laparotomies performed in search of an intestinal perforation would certainly compromise their already precarious conditions.

Enterocolitis, Pseudomembranous↗

The effects of CO2 pneumoperitoneum on hemodynamics in hemorrhaged animals.

BACKGROUND: Carbon dioxide (CO2), the primary gas currently used for pneumoperitoneum, has been known to cause systemic effects on acid-base balance and hemodynamic stability. We studied the hemodynamic effects of CO2 pneumoperitoneum in a hemorrhagic shock model to assess the safety of laparoscopic procedures in acute trauma patients. METHODS: After 1 hour of baseline, 32 anesthetized adult pigs were randomized into four groups. Group 1 animals had no hemorrhage, serving as a control group. Group 2 animals had a mild hemorrhage of 10 ml/kg/hr. Group 3 animals had a moderate hemorrhage of 20 ml/kg/hr. Group 4 animals had a moderate hemorrhage but were resuscitated with 40 ml/kg of lactated Ringer's solution. All animals were then insufflated to an intraabdominal pressure of 15 mm Hg with CO2 gas for 1 hour. The abdomen was then decompressed, and the animals were observed for another hour. All animals survived hemorrhage. One death each occurred in moderate hemorrhage groups, both near the end of CO2 pneumoperitoneum. These animals were not included in statistical analysis. RESULTS: In euvolemic animals, CO2 pneumoperitoneum induced hypercapnia (from 34 +/- 1 mm Hg to 48 +/- 1 mm Hg), acidemia (from 7.45 +/- 0.02 to 7.36 +/- 0.02), and a 20% reduction in stroke volume. Mild hemorrhage and CO2 insufflation resulted in a similar degree of acidemia (7.35 +/- 0.01), but moderate hemorrhage and CO2 insufflation led to more severe acidemia (7.26 +/- 0.02). Fluid resuscitation failed to prevent this severe fall in pH (7.30 +/- 0.03) for group 4. PaCO2 was not affected by hemorrhage, but CO2 pneumoperitoneum induced significant hypercapnia in all groups, ranging from 48 +/- 1 mm Hg for euvolemic animals to 52 +/- 1 mm Hg for moderate hemorrhage animals. Stroke volume declined as a function of blood loss, and it was further depressed by CO2 insufflation, to as low as 75% of baseline in mild hemorrhage and 55% of baseline in moderate hemorrhage. Both stroke volume and cardiac index initially responded to large-volume fluid replacement after moderate hemorrhage but quickly decreased to levels comparable to those of unresuscitated animals when CO2 pneumoperitoneum was created. CONCLUSIONS: Intraperitoneal insufflation with CO2 for diagnostic laparoscopy may be hazardous in acute hypovolemic trauma patients.

Animals↗