What is the etiology and treatment of post-laparoscopy pain?
A major advantage of laparoscopic surgery compared with open procedures is the reduction in postoperative pain. However, pain is still a problem. The etiology of the pain is multifactorial and amenable to maneuvers that may decrease its incidence.
With insufflation, there is distention of the abdomen with a resultant phrenic nerve neuropraxia. A 20% stretch of the nerve results in occlusion of the endoneural vessels and consequent nerve ischemia. The greater the time the nerve has to adapt to the stretch, the less likely nerve injury will occur. The use of reduced insufflation rates and sub-diaphragmatically administered local anesthetics may aid in the reduction of pain.
The phrenic nerves may be damaged by the acid milieu created by the dissolution of CO2 used for insufflation. Potential neural injury may be minimized by shorter exposure to the implicated gases.
If the insufflating gas is not evacuated adequately, the intra-abdominal acidosis and consequent irritation may persist for a prolonged period of time causing damage. Residual gas may also result in loss of peritoneal surface ten-sion and support to the abdominal viscera, also contributing to postoperative pain. The greatest reduction in postopera-tive pain is seen when warmed, humidified gases are used.
Local anesthesia administered into the incision sites before the wounds are created is believed by some, but not all, to be associated with significant reduction in postoper-ative pain. More commonly the wounds are injected with local anesthetic just prior to closure. Only small amounts of anesthetic are necessary for the small wounds associated with laparoscopic procedures and minimal side-effects are therefore expected. The use of local anesthetic infiltration is therefore recommended.
Nonsteroidal anti-inflammatory medications adminis-tered after the induction of anesthesia have useful opioid sparing and anti-inflammatory effects. Ibuprofen is a reasonable alternative to fentanyl in the reduction of both postoperative pain and nausea after outpatient procedures.