Interstitial emphysema associated with epidural anesthesia for extracorporeal shock-wave lithotripsy

Pseudo-pneumoretroperitoneum secondary to lumbar emphysema: CT demonstration in two cases

Several conditions may simulate the radiolucent appearances of pneumoretroperitoneum at plain film. These include gas shadows in locations other than the retroperitoneal space or fluid within the retroperitoneal compartments. Two cases of emphysema within the soft tissues of the back mimicking pneumoretroperitoneum on plain radiographs are described. One case was secondary to epidural anesthesia and another to trauma. In both, computed tomography (CT) led to the correct diagnosis. The possible pitfalls in the differential diagnosis of retroperitoneal gas are described with emphasis of the diagnostic role of CT.

Retroperitoneal air, extracorporeal shock wave lithotripsy and epidural anesthesia

During a 13-month period, 1,344 patients underwent extracorporeal shock wave lithotripsy. Plain x-rays done routinely 24 hours after lithotripsy to assess stone fragmentation revealed evidence of retroperitoneal air in 6 patients. All 6 patients had epidural anesthesia induced by loss of resistance to air in a syringe to identify the epidural space. It was believed likely that this was the cause of the air and 2 types of distribution were identified: 1 showed tracking of air along spinal nerves and 1 along tissue planes. This hypothesis eventually was confirmed by 2 patients in whom the air was identified after epidural anesthesia but before extracorporeal shock wave lithotripsy. Retroperitoneal air is found in a small number of patients undergoing epidural anesthesia and extracorporeal shock wave lithotripsy, and physicians treating these patients in the early postoperative period should be aware of this possible radiological finding and appreciate its benign nature.

[Anesthesia for extracorporeal lithotripsy in the treatment of renal lithiasis]

Extracorporeal shock wave lithotripsy has become the main technique for treating renal lithiasis. It has many repercussions on anaesthesia. The fundamental technical concepts of lithotriptors are reviewed. The problems due to the different systems (electrohydraulic or piezoelectric--the most widespread in France) are discussed. Electrohydraulic systems, which are more adapted to the treatment of large stones (diameter greater than 2 cm), require the immersion of the patient. As a result, there are analgesic, cardiovascular, respiratory and temperature repercussions on the anaesthetic management of these patients. General anaesthesia is generally more appropriate for this technique. On the other hand, piezoelectric systems are more adapted to the treatment of medium-sized or small calculi (diameter less than 2 cm), and do not require immersion. Anaesthesia is often not required for the use of this technique, but, if necessary, local, regional or general anaesthesia may be used. For either technique, the anaesthetic protocol must be adapted to the patient's and the surgical indications.