The ports should be chosen with the specific procedure in mind, taking into account the surgeon’s preference, cost and what exact instrumentation will be needed.

There are many different trocar tips available, each with its own benefits and limitations. Pyramidal tips are reputed to cause more damage than conical tips; however, conical tips require excessive force to introduce. The knife blade tip theoretically causes less abdominal wall trauma; however, it cannot be introduced using the usual twisting method. Reusable trocars may become dull over time (Video 1.3).

Many feel that shielded trocars are safer; however, they do not tend to be as easily introduced, leading to a greater amount of pressure being applied. The shield is supposed to pop out and lock around the blade once the trocar has entered the abdomen. However, if the skin incision is too small, the shield may be held back. Newer shielded trocars with a blade that retracts into the shield should eliminate this problem. Some newer cannulas minimise dangers associated with trocars. One is a disposable expandable sleeve, which is introduced using the Veress needle and then dilated to the necessary size using a blunt introducer. The other is a reusable threaded cannula, which is introduced through a small incision in the anterior fascia. Using rotational force, under direct vision, it bluntly dissects its way into abdomen. Another one is a disposable cannula with a bladeless trocar that is introduced under laparoscopic view by dilating the tissues. Both are reported to decrease trauma to the abdominal wall structures, as well as leaving smaller defects to close. No matter which product is used, careful controlled entry is the key.

Cardiovascular/haemodynamic and pulmonary changes associated with the pneumoperitoneum represent a complex balance between the factors mentioned above. Carbon dioxide insufflation may also affect acid-base balance and may lead to further deterioration of existing intraperitoneal sepsis or inflammation.

Insufflation of the abdominal cavity and elevation of intra-abdominal pressure have three predominant mechanical effects on cardiovascular functions:

Isolated elevation of intra-abdominal pressure produces compression of the splanchnic circulation, resulting in increased afterload and depression of cardiac function.

The increased abdominal pressure has an effect similar to positive end-expiratory pressure (PEEP) on haemodynamic variables. Thus, in animal studies, a decrease in cardiac output with concomitant increase of the central venous pressure and the peripheral systemic vascular resistance was observed after implementation of pneumoperitoneum [9]. Some other studies did not report on significant changes in cardiac output, while mean arterial pressure, systemic vascular resistance and central venous pressure were elevated [10].

In high-risk cardiac patients, the effect of CO₂ pneumoperitoneum is more pronounced as compared to healthy individuals [11]. In addition, another study showed a decrease in heart rate and cardiac output without the compensatory mechanism of an elevated systemic venous resistance. The authors suggested that mixed venous oxygen saturation is the most sensitive parameter in monitoring cardiovascular function [12].

Pressure-related effects of pneumoperitoneum include decreased blood flow through the inferior vena cava. This in turn leads to reduced filling volume and pressure in the right and left atrium with consequent decrease in preload. According to the Frank-Starling law, this effect can be compensated up to a point after which the cardiac output falls. Increases in central venous pressure due to higher intrathoracic pressure during mechanical ventilation and additional pneumoperitoneum falsely suggest sufficient volume status. Therefore, a decrease in cardiac output is the sequel of decreased preload, which is compensated by an increase in afterload from a rise in systemic venous resistance. The net effect is a stable or slightly decreased cardiac output and mean arterial pressure under normal conditions, i.e. adequate cardiac reserve and sufficient volume status. There is evidence that increasing intra-abdominal pressure decreases splanchnic blood flow, which adversely affects mucosal microcirculation.