Intra Abdominal Explosion

The use of pure oxygen for pneumoperitoneum was abandoned after Fervers' (148) 1933 report of an intra-abdominal explosion during laparoscopy with oxygen insufflation. N2O supports combustion (149) and is explosive in the presence of methane or

FIGURE 6 ■ Possible routes of gas into mediastinum, pericardial sac, or pleural cavity during laparoscopy include persistent fetal connections at the site of pleuroperitoneal membrane (A1, forme fruste of diaphragmatic hernia), pleuropericardial membrane (A2), and pericardioperitoneal canal (A3); leakage of gas through intact membrane at a weak point such as diaphragmatic hiatus (B1), at pulmonary hilum (B2), and pericardial sac alongside blood vessels (B3); gas outside membrane-bound cavities such as pro- or retroperitoneal gas in between fibers of the diaphragm or alongside great vessels (C1) or subcutaneous gas from the anterior neck (C2); gas from the rupture of an airspace (baro-trauma) enters the mediastinum or pleural cavity by dissecting along the pulmonary vasculature (D). Source: From Ref. 122.

To reduce the risk of explosion, both inhaled and insufflated N2O should be avoided when electrocautery or laser might be used.

hydrogen (150). Although the necessary conditions for explosion in association with N2O pneumoperitoneum are rare (151), cardiac rupture and death from an explosion during N2O pneumoperitoneum has been reported (152). Hydrogen at a concentration of 69% (the maximum reported content of hydrogen in bowel gas) is combustible in the presence of 29% N2O (153). It has been determined that when the anesthetic gas contained 60% N2O, the N2O content in the peritoneal cavity increased to 36% after 30 minutes of CO2 pneumoperitoneum (153).

To reduce the risk of explosion, both inhaled and insufflated N2O should be avoided when electrocautery or laser might be used.

Even without N2O insufflation, electrocautery injury to the colon can produce explosion (154).

As demonstrated by Doppler flow studies, the increased intra-abdominal pressure of pneumoperitoneum diverts blood from the splanchnic circulation into the lower extremities, with subsequent lower-extremity venous engorgement and stasis during transperitoneal laparoscopy.

FIGURE 7 ■ Pneumoperitoneum promotes lower-extremity venous engorgement and stasis. Source: From Ref. 122.

The relative risk of thrombotic complications following laparoscopic surgery compared to open surgery is unknown. Until certain laparoscopic procedures have been determined to be at very low risk, prophylaxis against venous thrombosis is recommended.

Intravenous fluid requirements during laparoscopy are less than during open surgery. The combination of decreased insensible losses (no body cavity open to air) and decreased urine output predisposes patients to volume overloading during laparoscopy.

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