Various techniques are used to transect the liver. With increase in laparoscopic liver resections (LLR), it is of even more interest to develop surgical techniques to minimize bleeding and the risk for gas embolism during transection. Instrument like argon enhanced coagulator provides good hemostasis but increases the danger of gas embolism. The CO2 pneumoperitoneum that is routinely used in most types of laparoscopic surgery can be modified by the use of different gas pressure. It can be assumed that different pressure influences bleeding but also the risk for gas embolism. In presented porcine studies, three instrumental combinations have been studied. In study I sixteen piglets were randomized to LLR with either the cavitron ultrasonic aspirator (CUSA™) in combination with vessels sealing system (Ligasure™) or with CUSA™ and ultrascision scissors (Autosonix™), with the endpoints of intra-operative bleeding and gas embolism.  In study IV sixteen piglets were randomized to LLR either with staple device (Endo-GIA™) or the Ligasure™ - CUSA™ combination with same primary endpoints and additionally secondary endpoints of effect on gas-exchange, systemic- and pulmonary hemodynamic. Focusing on intra-abdominal pressure (IAP) in study II, sixteen piglets were randomized to LLR with an IAP of either 8 or 16 mmHg.  Primary endpoints were bleeding and gas embolism and secondary endpoints, effect on gas-exchange, systemic- and pulmonary hemodynamic. In study III effect of argon gas was tested during LLR. Sixteen piglets were randomized to either argon pneumoperitoneum or CO2 pneumoperitoneum. Primary endpoints were effect on gas-exchange, systemic- and pulmonary hemodynamic. In presented studies, we tested efficacy and safety of different techniques for LLR. CUSA™ can be used in combination with either Ligasure™ or Autosonix™. However, Ligasure™ reduces the amount of bleeding. The recent introduction of staplers seems promising with a further reduction in bleeding, gas embolism, and operating time. The IAP influences both the amount of bleeding as well as gas embolism. It seems reasonable to use a higher IAP to decrease bleeding with caution and with close monitoring for gas embolism. Argon gas embolism gives more extensive effect on gas-exchange and hemodynamic and should probably be avoided in this type of surgery.

Laparoscopic liver surgery is complicated due to the structure of this organ with open sinusoids. A serious disadvantage is the risk of gas embolism (GE) due to CO2 pneumoperitoneum. CO2 can enter the vascular system through a wounded vein. A common opinion is that gas fluxes along a pressure gradient, e.g. CVP-intra abdominal pressure (IAP). The occurrence of GE could also be eased by entrainment, a ‘Venturi-like’ effect, due to cyclic differences in thoracic pressure and blood flow caused by mechanical ventilation at normal frequency. The aims of these studies were to survey, in a porcine model, the influence on respiratory and haemodynamic variables by GE, to determine at what frequency, severity and duration GE occurs during laparoscopic liver resection (LLR) and whether there are methods to influence the occurrence or severity of GE. Pulmonary and circulatory variables were monitored and measured as well as continuous blood gas monitoring. Transoesophageal echocardiogram was used to identify GE and, according to the amount of bubbles in the right outflow tract of the heart, GE was graded as 0, 1 and 2. Pneumoperitoneum was created by using CO2and IAP was set to 16 mm Hg. A single bolus dose of CO2 influenced respiratory and haemodynamic variables for at least 4 h. During LLR GE occurred in 65-70% of the animals, of which the more serious caused negative influence on cardiopulmonary variables. Elevated PEEP (15 cm H2O) increased CVP but GE occurred irrespective if CVP was lower than or exceeded IAP. In two last studies, a hepatic vein was cut and left open for 3 m before it was clipped. Interestingly, no signs of GE were seen despite an open vein and IAP > CVP in 8 of 20 animals. In the last study high frequency jet ventilation was used in order to minimise the risk of entrainment. The duration of GE was shortened. The occurrence of GE seemed to be influenced by several different factors. The physiological reaction of a GE is impossible to predict for a specific patient, and depends among other factors on comorbidity, and amount, site and entrance rate of GE.

Hintergrund: Die Verletzung eines großen, venösen Gefäßes während eines lapa-roskopischen Eingriffs könnte die Entstehung einer fulminanten Gasembolie begüns-tigen. Die Verwendung von Helium als Insufflationsgas könnte aufgrund der geringen Löslichkeit ein deutlich erhöhtes Auftreten klinisch relevanter Gasembolien verursa-chen. Methodik: Bei insgesamt 20 Versuchstieren wurde unter Verwendung von CO2 [n=10] oder Helium [n=10)] als Insufflationsgase die Vena Cava inferior laparoskopisch inzi-diert. Nach 30 Sekunden wurde die Vene abgeklemmt, die Inzision laparoskopisch genäht und die Vene wieder geöffnet. Perioperativ wurden kontinuierlich Herzfre-quenz (HF), mittlerer arterieller Blutdruck (MAP), pulmonal arterieller Druck (PAP), pulmonal arterieller Verschlußdruck (PAWP), zentralvenöser Druck (ZVD), endexspi-ratorisches CO2 (ETCO2), Herzminutenvolumen (HMV), arterielle Blutgase (pH, Pa-CO2, PaO2) und arterielle Sauerstoffsättigung bestimmt. Ergebnisse: Die Letalität betrug 0% (mittlerer Blutverlust CO2, 157±50 ml; Helium, 173±83 ml). HMV und MAP zeigten in beiden Gruppen nach Inzision der Vene einen Abfall, der jedoch nach kurzer Zeit wieder vollständig kompensiert wurde. Das en-dexspiratorische CO2 stieg signifikant nach Beginn der CO2 Insufflation an (p / Background: Injury of venous vessels during elevated intraperitoneal pressure is thought to cause possible fatal gas embolism, and helium may be dangerous be-cause of its low solubility. Methods: Twenty pigs underwent laparoscopy with either CO2 (n=10) or helium (n=10) with a pressure of 15 mmHg and standardized lacera-tion (1 cm) of the vena cava inferior. After 30 s, the vena cava was clamped, closed endoscopically by a running suture and unclamped again. During the procedure changes of cardiac output (CO), heart rate (HR), mean arterial pressure (MAP), cen-tral venous pressure (CVP), pulmonary artery pressure (PAP), pulmonary artery wedge pressure (PAWP), end tidal CO2 pressure (PETCO2), and arterial blood gas analyses (pH, pO2 and pCO2) were investigated. Results: No animal died during the experimental course (mean blood loss during laceration: CO2, 157±50 ml; helium, 173±83 ml). MAP and CO values showed a decrease after laceration of the vena cava in both groups that had already been completely compensated for before sutur-ing. PETCO2 increased significantly after CO2 insufflation (P