الفهرس 
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Abstract
Percutaneous renal access while a patient is in the prone position has been firstly introduced by Goodwin et al (Goodwin et al., 1955), Fernstrom and Johansson in 1976 reported the first trial of extracting renal stone through a nephrostomy tract. Alken et al in 1981 published a study of percutaneous stone disintegration using an ultrasound lithotrite which wasoriginally developed for lithotripsyof vesical calculi. Since then, percutaneous nephrolithotomy (PCNL) has been widely adopted allover the world and its indications become well outlined(Skolarikos et al., 2005).
The indications of PCNL are extended after several years of experience to include large renal stones, staghorn calculi, stones resistant to fragmentation by shock wave lithotripsy, or stones in kidneys with an abnormal anatomy(Tiselius et al.,2001; Preminger et al.,2005).
Traditionally, PCNL has been performed while a patient in the prone position because it is believed a safe position providing posterior access to the collecting system and easier puncture of a posterior calyx through Brodel’s – less vascular- renal plane without causing excessive bleeding, peritoneal or visceral injuries(Wolf and Clayman, 1997; Alken et al. 1981).
However,the prone positionis often associated with restricted respiratory movement (Michelet al.,2007) and may be associated with decreased lung compliance and reduced chest wall and diaphragmatic movement due to abdominal compression. The cardiac output may also be reduced, thus, a patient has traditionally been placed onjelly rolls andpillows, with or without a roll bar under lower ribs to push the kidneys more posteriorly. These maneuvers are of significant importance andmay pose significant challenge to the anesthetist (Athanasios et al., 2009)
Obligation to change patient ’s position intraopertively is another drawback of the prone position , because insertion of a ureteral catheter is done in the dorsal lithotomy position, then the patient is turned into the prone one which may be time consuming, with risk of tube dislodgement, neck or limb injury. In some patients with skeletal deformities prone positioning may be impossible(Clayman et al., 1987;Valdivia et al., 1995; Valdiviaet al., 1998, Rana et al., 2008). Addtionally, prone position does’t completely reduce complications; massive bleeding and transfusionare reported in 3–10% and bowel injury was detected in 0.5% of cases (Joneset al.,1990).
Thus, morbid obesity, cardiopulmonary diseases, and skeletal deformities are significant risk factors in PCNL in prone postion (Zhou et al.,2008).
The progressively increased surgeon’s confidence and experience in PCNL; another ideas.