Dr Sumit More
ILSS, Faridabad, Haryana
RIRS is rapidly gaining popularity for management of renal stones up to 20mm or even larger. Residual fragments, which remain after the RIRS, are associated with a 20% to 43% rate of stone events, including pain, stone regrowth, infection, emergency department visits, hospital admissions, and additional procedures.(1) Infectious complications in RIRS are due to raised intrarenal pressure and potentially raised intrarenal temperature. Good flow of irrigation fluid reduces the temperature and improves visibility and use of suction increases the outflow of the irrigation fluid thus, reducing the intrarenal pressure.
Suction technique in RIRS can be divided broadly into: suction outside scope via suction ureteral access sheath (UAS) or suction through scope - Direct In Scope Suction (DISS)
With suction UAS, there is continuous suction, vision is better and continuous lasing can be performed reducing the operative time while improving stone free rates.(2) Bendable or malleable suction UAS can be navigated across the PUJ in the stone bearing calyx. There is a risk of mucosal bleeding if the negative pressure becomes too high inside the PCS. This can be reduced by employing low power suction machine and a trained assistant for operating the suction. Placing the bendable UAS across the PUJ has its own demerits also and might led to ischemia of at PUJ is placed for prolonged time and also prevents the use of secondary deflection of the scope to maneuver into difficult calyces. Small scopes (7.5 Fr) with at least 11-13Fr UAS is beneficial for superior fragment removal (average size of particle is around 0.42mm -0.58 mm) but in a third of the patients a 11-13 Fr access sheath cannot be passed into the ureter in an unstented patient, thereby requiring additional procedures.
DISS is simple, sterile and cost effective and doesn’t needs special equipment.(3) The suction is controlled and is equally effective with or without the UAS. It is especially useful in a tight ureter, primary RIRS, stented patients when there is still little turbidity in the PCS and in calyceal diverticular and lower calycial stones. The suction uses the irrigation channel of the flexible scope as a conduit for aspiration of dust, however there is potential risk of channel clogging and scope damage. A continuous suction cannot be performed as the PCS will collapse once the suction is applied. To prevent stone impaction in the channel of the scope, suction needs to be applied with the laser fiber in situ, the heap of dust should not be poked and one should stop as soon as a large fragment is stuck at the tip of scope. Another limitation is that it requires an experienced assistant.
Using Suction in RIRS has the potential to minimize the need for accessories and additional interventions, making this a potential game changer.
Figure 2: Suction Ureteral access sheath
Figure 3: Assembling the DISS device A) Adaptor B,C) attached to scope D) handling the scope
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