Laparoscopy in high-risk cardiac patients

Fifteen patients with severe cardiac disease (American Society of Anesthesiologists III or IV) underwent laparoscopy using radial artery and pulmonary artery catheters to determine intraoperative hemodynamic changes. Cardiac output (CO), mean arterial blood pressure (MAP), central venous pressure, heart rate, systemic vascular resistance (SVR) and mixed venous oxygen saturation (SVO2) were recorded before anesthetic induction, after induction, but before peritoneal insufflation, after insufflation and after release of pneumoperitoneum. Peritoneal insufflation led to significant elevations in MAP and SVR and reduction in CO. For seven patients, a decrease in SVO2 after peritoneal insufflation was predictive of significant worsening of hemodynamic parameters, suggesting inadequate cardiac reserve. In all patients, hemodynamic parameters returned toward baseline once pneumoperitoneum was released. There were no perioperative cardiac complications. While it is evident that laparoscopy presents serious hemodynamic stress, it can be performed safely in high-risk patients, using aggressive intraoperative monitoring.     

Blood gas changes during laparoscopic cholecystectomy--comparative study of N2O pneumoperitoneum and CO2 pneumoperitoneum

During laparoscopic cholecystectomy by alternative insufflation of nitrous oxide and carbon dioxide, the changes of blood gas tensions were measured and analyzed in 12 patients. During N2O insufflation, PaO2 decreased by about 25 mmHg and PaCO2 was unaltered compared with the values before pneumoperitoneum. While during CO2 insufflation, PaO2 decreased by about 13 mmHg and PaCO2 increased by about 6 mmHg. We considered that decrease in PaO2 during N2O insufflation was associated with not only uneven ventilation/blood flow ratios but also with the reduction in the alveolar O2 tension caused by the diffusion of N2O absorbed from the peritoneum. PaCO2 increases during CO2 insufflation because CO2 is absorbed from the peritoneum, and is not excreted entirely through the lungs.     

Influence of age on cardiac pump function during laparoscopic cholecystectomy--measurements by ear densitography

Using ear densitography, consisting of photoelectric plethysomography and Holter electrocardiography, we measured systolic time intervals (STI) in 21 patients, ASA class 1 and 2, undergoing laparoscopic cholecystectomy using CO2 insufflation under general anesthesia (neuroleptanesthesia with isoflurane in air, FIO2 0.5). The patients were divided into two groups: Y-group (10 patients under 59 years of age) and O-group (11 patients over 60 years of age). We investigated the influence of age on cardiac pump function during pneumoperitoneum non-invasively. Y-group showed improvement of cardiac pump function (reduction of PEP/LVET) from 30 minutes after the beginning of insufflation and quick recovery of cardiac function immediately after deflation. O-group showed a tendency of increasing PaCO2 and arterial diastolic pressure, and delayed recovery of cardiac function (elongation of PEP at 60 minutes, and increase of PEP/LVET at 60 and 90 minutes, respectively, after insufflation). Hypertension and tachycardia were apparent immediately after pneumoperitoneum in the O-group. We conclude that special care and monitoring are mandatory for the aged patients with impaired cardiac or respiratory function during laparoscopic surgery.     

Clinical study of gasless laparoscopic adrenalectomy in 17 cases--comparison between laparoscopic adrenalectomy with and without pneumoperitoneum

PURPOSE: To determine the efficiency of gasless laparoscopic adrenalectomy, this procedure was compared to that with pneumoperitoneum. PATIENTS AND METHODS: Between February 1994 and December 1996, 17 gasless laparoscopic adrenalectomy were performed in 5 men and 12 women, 36 to 79 years old. Clinical diagnosis was primary aldosteronism in 8, pheocromocytoma in 2, incidentaloma in 4 and adrenal cyst in 3. When gasless laparoscopic adrenalectomy was performed, the laparoscope was inserted through the upper margin of the umbilicus by open laparotomy. To create a workable space, a 1.2 mm Kirschner wire was advanced subcutaneously below the costal arch and attached to a retractor. Operating time, estimated blood loss, changes of the end tidal CO2 concentration during operation, operative complications and postoperative course were compared to those with pneumoperitoneum in 12 cases. RESULTS: In both procedures, satisfying workable spaces were created in all cases. The mean operating time and estimated blood loss were 245 min and 201 ml without pneumoperitoneum, 317 min and 274 ml with pneumoperitoneum, respectively. The mean changes of end tidal CO2 concentration during operation were 3.2 mmHg without pneumoperitoneum and 5.1 mmHg with pneumoperitoneum. As operative complications, open operations were required in 2 cases (1 without pneumoperitoneum and another with pneumoperitoneum) to control intraoperative bleeding. They had the histories of transabdominal operations. Postoperative bleeding was observed in 2 cases (1 without pneumoperitoneum and another with pneumoperitoneum). One of them (with pneumoperitoneum) needed surgical management for hemostasis. Fever over 38 degrees C that occurred in 1 case with pneumoperitoneum appeared to be absorption fever. No differences were observed in the number of the days to the start of oral intake and for postoperative hospitalization between the two groups. CONCLUSIONS: Gasless laparoscopic adrenalectomy is available for most adrenal tumors. Suction could be used unrestrictedly and there were no hemodynamic or ventilatory effects due to pneumoperitoneum. This procedure appears to be safe and advantageous for the treatment of most adrenal tumors.     

Hemodynamic changes during laparoscopic cholecystectomy

Hemodynamics during laparoscopic cholecystectomy under general anesthesia (isoflurane in N2O/O2 (50%)) were investigated in 15 nonobese ASA Class I patients by using invasive hemodynamic monitoring including a flow-directed pulmonary artery catheter. During surgery, intraabdominal pressure was maintained automatically at 14 mm Hg by a CO2 insufflator, and minute ventilation was controlled and adjusted to avoid hypercapnia. Hemodynamics were measured before anesthesia, after the induction of anesthesia, after tilting into 10 degrees head-up position, 5 min, 15 min, and 30 min after peritoneal insufflation, and 30 min after exsufflation. Induction of anesthesia decreased significantly mean arterial pressure and cardiac index (CI). Tilting the patient to the head-up position reduced cardiac preload and caused further reduction of CI. Peritoneal insufflation resulted in a significant increase (+/- 35%) of mean arterial pressure, a significant reduction (+/- 20%) of CI, and a significant increase of systemic (+/- 65%) and pulmonary (+/- 90%) vascular resistances. The combined effect of anesthesia, head-up tilt, and peritoneal insufflation produced a 50% decrease in CI. Administration of increasing concentrations of isoflurane, via its vasodilatory activity, may have partially blunted these hemodynamic changes. These results demonstrate that laparoscopy for cholecystectomy in head-up position results in significant hemodynamic changes in healthy patients, particularly at the induction of pneumoperitoneum.     

Characteristics of underserved women who did and those who did not use a free/low-cost voucher as part of a mammography screening program

The effects of pneumoperitoneum on peak venous flow velocity in the common femoral vein and the vena cava have already been studied. The results suggested that venous stasis occurs during surgical pneumoperitoneum. This study determines the effects of pneumoperitoneum on the overall venous outflow resistance of the lower limbs. Venous outflow resistance was measured during surgical procedures by impedance plethysmography in 12 patients undergoing laparoscopic cholecystectomy, 4 patients undergoing laparoscopic herniorrhaphy, 4 patients undergoing conventional cholecystectomy, and 2 patients undergoing conventional herniorrhaphy. Venous outflow resistance did not change significantly during laparoscopic cholecystectomy or herniorrhaphy. No difference in venous outflow resistance between laparoscopic cholecystectomy and herniorrhaphy was found. During pneumoperitoneum, no obstruction to total lower limb venous outflow could be demonstrated, indicating that venous stasis in the limbs did not occur, and consequently, flow in the iliac and inferior caval veins was not compromised. Hypothetically, active vasodilatation resulting from mild compression may explain this. In our view, no special measures to prevent deep venous thrombosis have to be taken during laparoscopic procedures.     

CO2--emphysema in laparoscopic surgery. Changes in pulmonary CO2-elimination

We report on two patients with subcutaneous carbon dioxide (CO2) emphysema that developed during laparoscopic surgery with CO2 pneumoperitoneum (PP), in whom pulmonary elimination of CO2 (ECO2, Servo ventilator with integrated CO2 analyzer 930, Siemens) was continuously monitored. Patient 1 was a 61-year-old man with laparoscopic herniotomy. ECO2 immediately before PP was 120 ml/min x m2 and increased rapidly after 45 min PP to a maximum value of 340 ml/min x m2. At that time, minute ventilation had been increased from 7 to 11 l/min and PaCO2 had risen from 35 to 57 mm Hg. At the end of the procedure the patient showed excessive subcutaneous emphysema. Patient 2 was a 71-year-old woman in whom diagnostic laparoscopy was performed for staging of a pancreatic tumor. ECO2 immediately before PP was 140 ml/min x m2, increasing dramatically after 45 min PP to a maximum value of 529 ml/min x m2 (Fig. 1). At that time minute ventilation had been increased from 6.2 to 12.5 l/min and PaCO2 had risen from 40 to 77 mm Hg. PP was terminated and the patient was found to have extreme subcutaneous emphysema. She was mechanically ventilated for a further 40 min to normalize PaCO2 and ECO2. It seems reasonable to suppose that an increase in ECO2 by more than 100% of control during CO2-PP is an early sign of CO2 emphysema. In this situation hypercapnia is potentially life-threatening. Evidently, reabsorption of CO2 from loose connective tissue is far more rapid and effective than CO2 resorption from the peritoneal cavity.(ABSTRACT TRUNCATED AT 250 WORDS)     

Laparoscopic management of acute cholecystitis with subtotal cholecystectomy

Approximately 20 per cent of laparoscopic cholecystectomies performed for acute cholecystitis require conversion to open cholecystectomy because of severe inflammation. In a retrospective review of 125 consecutive patients undergoing laparoscopic surgery for gallbladder disease from January 1995 through June 1997, 31 had acute cholecystitis. Eight patients underwent a subtotal cholecystectomy because of severe inflammation. There were no conversions to open cholecystectomy and no intraoperative complications. Selected patients were evaluated and treated for common duct stones with preoperative endoscopy to avoid intraoperative cholangiography. One patient had a retained common duct stone successfully managed with postoperative endoscopy. Laparoscopic subtotal cholecystectomy is a safe and effective alternative to conversion to open cholecystectomy for severe inflammation associated with acute cholecystitis. Endoscopic assessment and treatment of common duct stones when indicated either before or after surgery omits the use of intraoperative cholangiography and potential injury to the inflamed ducts.     

Embryogenesis and functional development of the chick''s basilar papilla

BACKGROUND: After laparoscopy with carbon dioxide (CO2) insufflation early postoperative recovery is often complicated with drowsiness and postoperative nausea and vomiting (PONV). METHODS: 25 ASA I-II patients undergoing elective laparoscopic cholecystectomy under standardized anaesthesia were studied in a randomized, prospective study. The conventional CO2 pneumoperitoneum was compared with the mechanical abdominal wall lift (AWL) method with minimal CO2 insufflation with special reference to postoperative recovery. RESULTS: Postoperative drowsiness was of a significantly longer duration with the conventional method (p < 0.001) compared with the AWL technique. There was a positive correlation with the total amount of CO2 used and the duration of drowsiness (r = 0.75, p < 0.01). PONV was seen significantly more often in patients with CO2 insufflation of more than 121 (p < 0.05). CONCLUSIONS: Avoiding excessive CO2 is beneficial for smoother and more uneventful recovery after laparoscopic cholecystectomy.     

Helium pneumoperitoneum for laparoscopic cholecystectomy: ventilatory and blood gas changes

Laparoscopic cholecystectomy with carbon dioxide pneumoperitoneum may result in hypercarbia and acidosis in patients with cardiorespiratory disease. The aim of the present study was to assess helium as an alternative to carbon dioxide for creating the pneumoperitoneum. Ventilation requirements and carbon dioxide levels were assessed at the beginning and end of laparoscopic cholecystectomy using helium (n = 30) and carbon dioxide (n = 30) pneumoperitoneum. Insufflation with helium did not result in an increase in ventilation requirement although, like carbon dioxide pneumoperitoneum, it was associated with a mean rise in peak airway pressure (of 7 cmH2O; P < 0.001). There was also a 3.2-kPa increase in the alveolar-arterial oxygen gradient with helium (P = 0.006). Carbon dioxide pneumoperitoneum was associated with a significant rise in arterial carbon dioxide levels, despite increasing ventilation. Four patients with helium pneumoperitoneum had surgical emphysema for 5 days. Helium may be a suitable alternative to carbon dioxide for creating pneumoperitoneum in patients with severe cardiorespiratory disease. However, because of its low water solubility helium has a lower safety margin than carbon dioxide in the rare event of gas embolism.     

Laparoscopic cholecystectomy during pregnancy is safe for both mother and fetus

The use of laparoscopic cholecystectomy in pregnant women has been slow to gain wide acceptance for two reasons: one is the potential for mechanical problems related to the pregnant uterus and the other is fear of fetal injury resulting from instrumentation or the pneumoperitoneum. To assess the effects of laparoscopic cholecystectomy on both the mother and the unborn fetus, we reviewed our surgical experience over a 5-year period analyzing indications for the procedure along with complications and outcome. During this 5-year period, 22 patients ranging in age from 17 to 31 years underwent laparoscopic cholecystectomy during pregnancy. Gestational ages ranged from 5 to 31 weeks with two patients being in the first trimester, 16 in the second, and four in the third. The primary indications for surgical intervention were persistent nausea, vomiting, pain, and inability to eat in 17 patients, acute cholecystitis in three, and choledocholithiasis in two. In all patients a pneumoperitoneum was established by means of a closed technique starting in the right upper quadrant of the abdomen. Two of the 22 patients also underwent successful transcystic common bile duct exploration with removal of common duct stones. All 22 patients survived the surgical procedure without complications, and there were no fetal deaths or premature births related to the procedure. Based on the preceding results, it would appear that laparoscopic cholecystectomy during pregnancy is safe for both the mother and the unborn fetus. Indications for this procedure should include stringent criteria such as unrelenting biliary tract symptoms or the complications of cholelithiasis. If at all possible, when laparoscopic cholecystectomy is indicated, it should be performed either in the second trimester or early in the third.     

Laparoscopic cholecystectomy using the abdominal wall lift in a cardiac patient

We present a case report of a patient with impaired cardiac function after aortic valve replacement and open mitral commissurotomy who underwent a laparoscopic cholecystectomy for cholecystolithiasis. In preventing reduced cardiac output due to pneumoperitoneum, the laparoscopic operative procedure was performed using the abdominal wall lift. Cardiac function was continuously evaluated by transesophageal echocardiographic examination and remained stable during the surgery. Because of the patient's co-existing chronic atrial fibrillation and prosthetic aortic valve, perioperative anticoagulation management was carried out. The patient's post-operative course was uneventful, and he was discharged on the 7th post-operative day.     

The effects of cardiotoxic chemotherapy on blood pressure in patients with lymphoma

A retrospective study was carried in 1500 patients submitted to elective laparoscopic cholecystectomy to ascertain its feasibility in patients with previous abdominal surgery. In 411 patients (27.4%) previous infraumbilical intraperitoneal surgery had been performed, and 106 of them (7.06%) had 2 or more operations. Twenty five patients (1.66%) had previous supraumbilical intraperitoneal operations (colonic resection, hydatid liver cysts, gastrectomies, etc.) One of them had been operated 3 times. In this group of 25 patients the first trocar and pneumoperitoneum were performed by open laparoscopy. In 2 patients a Marlex mesh was present from previous surgery for supraumbilical hernias. Previous infraumbilical intraperitoneal surgery did not interfere with laparoscopic cholecystectomy, even in patients with several operations. There was no morbidity from Verres needle or trocars. In the 25 patients with supraumbilical intraperitoneal operations, laparoscopic cholecystectomy was completed in 22. In 3, adhesions prevented the visualization of the gallbladder and these patients were converted to an open procedure. In the 2 patients Marlex mesh prevented laparoscopic cholecystectomy because of adhesions to abdominal organs. We conclude that in most instances previous abdominal operations are no contraindication to laparoscopic cholecystectomy.     

Alterations in hepatic function during laparoscopic surgery. An experimental clinical study

BACKGROUND: Very few studies have been done on the consequences of pneumoperitoneum on hepatic function. At present, there is no consensus on the physiopathological hepatic implications of pneumoperitoneum. The purpose of this clinical study was to evaluate the effects of pneumoperitoneum on hepatic function in 52 patients treated with laparoscopic procedures. METHODS: Thirty-two laparoscopic cholecystectomies and 20 nonhepatobiliary laparoscopic procedures were performed in 52 patients (12 men and 40 women) with a mean age of 44 years (range, 15-74). All patients had normal values on preoperative liver function tests. The anesthesiologic protocol was uniform, with drugs at low hepatic metabolism. The 32 cholecystectomies were randomized into 22 performed with pneumoperitoneum at 14 mmHg and 10 performed at 10 mmHg. All nonhepatobiliary laparoscopic procedures were performed with a pneumoperitoneum of 14 mmHg. The postoperative serologic levels of AST, ALT, bilirubin, and prothrombin time were measured at 6, 24, 48, and 72 h. The serologic changes were related to the procedure, the duration, and the level of pneumoperitoneum. RESULTS: Mortality and morbidity were nil. All 52 patients had a postoperative increase in AST, ALT, bilirubin, and lengthening in prothrombin time. Slow return to normality occurred 48 or 72 h after operation. The increase of AST and ALT was statistically significant and correlated both to the level (10 versus 14 mmHg) and the duration of pneumoperitoneum. CONCLUSIONS: The duration and level of intraabdominal pressure are responsible for changes of hepatic function during laparoscopic procedures. Although no symptom appears in patients with normal hepatic function, patients with severe hepatic failure should probably not be subjected to prolonged laparoscopic procedures.     

Management of choledocholithiasis in patients undergoing laparoscopic cholecystectomy

The development of laparoscopic cholecystectomy has rekindled the issue of management of choledocholithiasis. A number of options exist including pre or postoperative endoscopic sphincterotomy (ERCP-ES), laparoscopic common duct exploration or open common duct exploration. We present here our experience with the management of choledocholithiasis in patients treated with laparoscopic cholecystectomy. From January 1991 to January 1995, 900 patients underwent laparoscopic cholecystectomy. 71 ERCP were carried out in 71 patients with suspicion or evidence of choledocholithiasis. Common duct stones were detected in 44 patients. Preoperative ERCP was done in 56 patients, with suspicion of choledocholithiasis, based on clinical, laboratory or ultrasonographic findings. 29 of these patients (51.7%) had common duct stones, that were successfully removed by endoscopic sphincterotomy. One patient suffered mild pancreatitis and a second one had transient hyperamylasemia. Postoperative ERCP was performed in 15 patients. Indications for ERCP were the evidence of common duct stones in intraoperative cholangiography in 7 cases, and clinical or laboratory suspicion of choledocholithiasis, 3 months to 3 years after laparoscopic cholecystectomy. Stones were detected in 100% of the patients. In 11 patients (73.3%), the stones were extracted by endoscopic sphincterotomy and 4 patients underwent open common duct exploration. Two patients had transient hyperamylasemia. ERCP is a safe and effective method for detection and treatment of common duct stones. ERCP prior to laparoscopic cholecystectomy in patients suspected of having choledocholithiasis, is safe and offers with good results. Rutinary intraoperative cholangiography is recommended, for the detection of unsuspected choledocholithiasis and as an effective treatment (postoperative-ERCP, open or laparoscopic common duct exploration) can be chosen depending on surgeon's skills and patient's characteristics.     

Lack of effect of CO2 on cerebral arterial diameter in man

STUDY OBJECTIVE: To establish the quantitative effects on the diameter of cerebral arteries following controlled changes in arterial carbon dioxide tension (PaCO2). DESIGN: Nonrandomized interventional study. SETTING: Angiography suite of a tertiary referral hospital. PATIENTS: 12 anesthetized patients suffering from a cerebral arteriovenous malformation undergoing endovascular treatment. INTERVENTION: Induced hypocapnia by hyperventilation and induced graded hypercapnia by the administration of carbon dioxide to the anesthetized patient's breathing circuit. MEASUREMENTS AND MAIN RESULTS: A digital angiography computer was used to make computerized measurements and calculations of the diameter of deep and small cortical arteries outside the vascular territory of cerebral arteriovenous malformations following controlled and standardized changes in PaCO2. Cardiovascular parameters were simultaneously measured and cardiac output (CO) calculated. No statistically significant changes in the diameter of cerebral arteries down to a size of 0.57 mm, which was the smallest artery studied, could be observed following changes in PaCO2 in the range between 28 +/- 4 mmHg and 74 +/- 4 mmHg. However, there was a 64% change in cardiac index following the above change in PaCO2. CONCLUSION: Deep cortical cerebral arteries down to a diameter of 0.57 mm seem to act merely as conductance vessels. The observed dramatic increase in CO following an increase in PaCO2 may offer an explanation for the changes in cerebral blood flow and cerebral flow velocity recorded by others and usually attributed to cerebral vasodilatation, which we were unable to demonstrate in this study.     

Late epigastric incisional hernias following laparoscopic cholecystectomy

By the introduction of laparoscopic cholecystectomy a new "gold standard" procedure became a routinely performed operation in the field of biliary tract surgery. Thus, the incision related early and late complications are thought to diminish, especially the formation of incisional hernias. Five patients had been referred to our department suffering from chronic incisional hernias following laparoscopic cholecystectomy. All of the hernias were located to the site of the epigastric trocar. The contents of the hernias proved to be omentum. The documentation's of the laparoscopic cholecystectomies revealed the extraction of thick walled gallbladders that contain large stones, and the wounds through which the extraction was performed had not been closed. Taking into consideration the fact of the "Chimney Effect" caused by the desufflation of the pneumoperitoneum at the end of the laparoscopic operation, bowel or omentum can easily escape through the relatively large wound formed during the extraction of the gallbladder, resulting in the formation of incisional hernias. This can be avoided by the complete desufflation and the prompt closure of the wound.     

Laparoscopic cholecystectomy in the geriatric population

OBJECTIVE: To assess effectiveness and conversion rates of inpatient laparoscopic cholecystectomy in older people living in the community. SETTING AND SUBJECTS: All acute care hospitals providing cholecystectomy in a single state. Medicare patients who underwent inpatient cholecystectomy in fiscal year 1994 in Arkansas. METHODS: A random sample comprising 449 of 2182 geriatric patients who underwent inpatient cholecystectomy in fiscal year 1994, stratified by hospital bed size, had charts reviewed for type of cholecystectomy performed, occurrence of conversion from a laparoscopic to an open cholecystectomy, surgical complications, and need for transfusion. RESULTS: Eighty-two percent of nonincidental cholecystectomies were initially laparoscopic. Total conversion rate for all inpatient laparoscopic cases was 20%. Forty-two percent of this group suffered acute cholecystitis with male patients exhibiting a higher rate of acute cholecystitis than female patients. Conversion rates for elective cholecystectomy for both sexes was between 13 and 14%. Conversion rate to an open procedures was 28% for patients with acute disease, with male patients again having a higher rate than female patients (40% vs 19%, P < .001). Surgical complications and intraoperative transfusions were rare. Conversion rates did not vary between large and small hospitals or among different age groups within the older population. CONCLUSIONS: Inpatient laparoscopic cholecystectomy is common in older people both for acute and chronic gallbladder conditions. Conversion rates ranged from 13% for elective cholecystectomy to 28% for acute disease. These rates are higher than published literature, which focuses on younger populations undergoing elective procedures. Audit committees need to be aware of this higher conversion rate in older people when assessing surgical proficiency.     

Serum erythropoietin and granulocyte-macrophage-colony stimulating factor levels with megadose methylprednisolone treatment

We described an anesthetic management of a patient with abdominal aortic aneurysm associated with dilated cardiomyopathy (DCM) focusing on preanesthetic evaluation of cardiovascular reserve and on intraoperative continuous circulatory monitoring with transesophageal echocardiography (TEE) and continuous cardiac output measurement (CCO). Based on echocardiographic and hemodynamic measurements after a 50 m-walk load, we predicted the allowable range of alteration of preload (LV diastolic dimension; Dd), myocardial performance (arterial blood pressure and ejection fraction) and of heart rate. During anesthesia and operation, we continuously monitored Dd, arterial blood pressure, heart rate and cardiac output, and maintained these variables within the allowable range. The changes in preload after clamping or unclamping of the aorta was promptly reflected by Dd as compared to pulmonary capillary wadge pressure. The CCO was also usuful in detecting abrupt changes in myocardial performance. In conclusion, we suggest preanesthetic stress test to be performed to evaluate cardiovascular reserve and to predict the allowable range of alteration of hemodynamic variables. Continuous monitoring of preload (Dd) by TEE and of myocardial performance by CCO is useful to detect early changes in these variables.     

Bitter taste of monosaccharide pentaacetate esters

We investigated the possibility of using argon, an inert gas, as a replacement for carbon dioxide (CO2). The tolerance of argon pneumoperitoneum was compared with that of CO2 pneumoperitoneum. Twenty pigs were anesthetized with enflurane 1.5%. Argon (n = 11) or CO2 (n = 9) pneumoperitoneum was created at 15 mm Hg over 20 min, and serial intravenous injections of each gas (ranging from 0.1 to 20 mL/kg) were made. Cardiorespiratory variables were measured. Transesophageal Doppler and capnographic monitoring were assessed in the detection of embolism. During argon pneumoperitoneum, there was no significant change from baseline in arterial pressure and pulmonary excretion of CO2, mean systemic arterial pressure (MAP), mean pulmonary artery pressure (PAP), or systemic and pulmonary vascular resistances, whereas CO2 pneumoperitoneum significantly increased these values (P < 0.05). During the embolic trial and from gas volumes of 2 and 0.2 mL/kg, the decrease in MAP and the increase in PAP were significantly higher with argon than with CO2 (P < 0.05). In contrast to CO2, argon pneumoperitoneum was not associated with significant changes in cardiorespiratory functions. However, argon embolism seems to be more deleterious than CO2 embolism. The possibility of using argon pneumoperitoneum during laparoscopy remains uncertain. Implications: Laparoscopic surgery requires insufflation of gas into the peritoneal cavity. We compared the hemodynamic effects of argon, an inert gas, and carbon dioxide in a pig model of laparoscopic surgery. We conclude that argon carries a high risk factor in the case of an accidental gas embolism.