Renogram Study With Percutaneous Nephrolithotomy (PERC): Alterations in Renal Blood Flow as a Consequence of PERC
| Status: | Completed |
|---|---|
| Conditions: | Renal Impairment / Chronic Kidney Disease, Nephrology |
| Therapuetic Areas: | Nephrology / Urology |
| Healthy: | No |
| Age Range: | 18 - Any |
| Updated: | 4/21/2016 |
| Start Date: | May 2005 |
| End Date: | February 2016 |
Alterations in Renal Blood Flow as a Consequence of Percutaneous Nephrolithotomy (PERC)
Patients with large or otherwise complex renal calculi are commonly treated by percutaneous
nephrolithotomy (PNL; PERC). PERC requires the creation of an approximately 10 mm channel
through the renal parenchyma, into the intra-renal collecting system, in order to effect
stone fragmentation and extraction. Although the nephrostomy tract is confined to a small
fraction of the renal parenchyma (approximately 1%), the trauma associated with the creation
of the tract will affect blood flow and oxygen delivery to regions beyond the immediate site
of injury. It is possible that this could result in a significant functional renal
impairment. There are several reports describing the effect of PERC on renal function, but
interpretation of these studies is difficult, due to a lack of uniformity in patient
selection and variability in the timing of peri-operative evaluation. Recent data from the
investigators' lab, obtained from a porcine model, suggest that, acutely, PERC causes a
significant decrease in renal function as measured by para amino hippurate (PAH) clearance.
The purpose of this study is to determine, in a rigorous and standardized fashion, the acute
effects of PERC on renal function, as measured by nuclear renography.
nephrolithotomy (PNL; PERC). PERC requires the creation of an approximately 10 mm channel
through the renal parenchyma, into the intra-renal collecting system, in order to effect
stone fragmentation and extraction. Although the nephrostomy tract is confined to a small
fraction of the renal parenchyma (approximately 1%), the trauma associated with the creation
of the tract will affect blood flow and oxygen delivery to regions beyond the immediate site
of injury. It is possible that this could result in a significant functional renal
impairment. There are several reports describing the effect of PERC on renal function, but
interpretation of these studies is difficult, due to a lack of uniformity in patient
selection and variability in the timing of peri-operative evaluation. Recent data from the
investigators' lab, obtained from a porcine model, suggest that, acutely, PERC causes a
significant decrease in renal function as measured by para amino hippurate (PAH) clearance.
The purpose of this study is to determine, in a rigorous and standardized fashion, the acute
effects of PERC on renal function, as measured by nuclear renography.
PERC is a commonly used technique to treat patients harboring large or complex renal
calculi. PERC is a particularly effective procedure, and has been associated with few
complications. However, the effect PERC has on renal functional parameters is not well
defined.
The effect of PERC on renal function has been examined in an animal model by several groups.
In one porcine model, the baseline renal function, as defined by PAH and creatinine
clearance, was compared to that measured at one month post-procedure. No acute data were
recorded, but the authors did note that although there was no significant change in renal
function at the one month follow-up point, there was a significant amount of renal scarring
present. This finding of significant renal scarring following PERC in an animal model has
been corroborated by others. One group has studied a canine model, and detected a
significant diminution of renal function (defined by creatinine clearance) at 48 hours
following PERC, and at 6 weeks following PERC renal function returned to normal. In human
subjects undergoing PERC, percutaneous tracts have also been associated with renal scarring.
These studies, both retrospective case series, did not capture strictly defined measures of
renal function, such as creatinine clearance, but rather compared pre- and post-procedure
serum creatinine as a surrogate for renal function. No significant change in serum
creatinine was identified in either study, but blood collections were performed at variable
times, in uncontrolled settings.
Nuclear renography is an imaging technique that records renal functional parameters. There
has been only one report of nuclear renographic assessment of the effect of PERC on renal
function. This report was an uncontrolled study, and the renograms were performed at a
median of 22 days post-procedure. At this time interval, it is not possible to derive any
conclusions regarding the acute effects of PERC on renal function.
The investigators have recently demonstrated in a porcine model that PERC is associated
acutely with significant deleterious effects on renal function. Following routine PERC,
glomerular filtration rate (GFR) and renal plasma flow (RPF) decline by 50% in both the
treated and the untreated kidney and return to normal when measured at 72 & 74 hours (n=3
pigs). Sodium excretion, however, was markedly below baseline at 72 and 74 hours in 2 of the
3 pigs. PAH extraction, a measure of the efficiency of renal tubular secretion of organic
anions, averaged 43.5 ± 9.7% and 42.6 ± 14.1% at 72 and 74 hours for the 3 pigs. These
values are substantially below the baseline value of 80.4 ± 4.0% measured in sham-PNL pigs.
To date, the examination of the effect of PERC on renal function has been restricted to
gross measures of function as defined by serum creatinine, and radionuclide studies
performed at a sub-acute interval following PNL, often without differential measurements or
controls. Importantly, the investigators' recent studies in a porcine model demonstrate that
PERC may cause significant alterations in renal function. There is a need to define in a
rigorous fashion the effect PERC has on renal blood flow and renal function. If a
deleterious effect is identified, future efforts can be focused on minimizing this insult.
calculi. PERC is a particularly effective procedure, and has been associated with few
complications. However, the effect PERC has on renal functional parameters is not well
defined.
The effect of PERC on renal function has been examined in an animal model by several groups.
In one porcine model, the baseline renal function, as defined by PAH and creatinine
clearance, was compared to that measured at one month post-procedure. No acute data were
recorded, but the authors did note that although there was no significant change in renal
function at the one month follow-up point, there was a significant amount of renal scarring
present. This finding of significant renal scarring following PERC in an animal model has
been corroborated by others. One group has studied a canine model, and detected a
significant diminution of renal function (defined by creatinine clearance) at 48 hours
following PERC, and at 6 weeks following PERC renal function returned to normal. In human
subjects undergoing PERC, percutaneous tracts have also been associated with renal scarring.
These studies, both retrospective case series, did not capture strictly defined measures of
renal function, such as creatinine clearance, but rather compared pre- and post-procedure
serum creatinine as a surrogate for renal function. No significant change in serum
creatinine was identified in either study, but blood collections were performed at variable
times, in uncontrolled settings.
Nuclear renography is an imaging technique that records renal functional parameters. There
has been only one report of nuclear renographic assessment of the effect of PERC on renal
function. This report was an uncontrolled study, and the renograms were performed at a
median of 22 days post-procedure. At this time interval, it is not possible to derive any
conclusions regarding the acute effects of PERC on renal function.
The investigators have recently demonstrated in a porcine model that PERC is associated
acutely with significant deleterious effects on renal function. Following routine PERC,
glomerular filtration rate (GFR) and renal plasma flow (RPF) decline by 50% in both the
treated and the untreated kidney and return to normal when measured at 72 & 74 hours (n=3
pigs). Sodium excretion, however, was markedly below baseline at 72 and 74 hours in 2 of the
3 pigs. PAH extraction, a measure of the efficiency of renal tubular secretion of organic
anions, averaged 43.5 ± 9.7% and 42.6 ± 14.1% at 72 and 74 hours for the 3 pigs. These
values are substantially below the baseline value of 80.4 ± 4.0% measured in sham-PNL pigs.
To date, the examination of the effect of PERC on renal function has been restricted to
gross measures of function as defined by serum creatinine, and radionuclide studies
performed at a sub-acute interval following PNL, often without differential measurements or
controls. Importantly, the investigators' recent studies in a porcine model demonstrate that
PERC may cause significant alterations in renal function. There is a need to define in a
rigorous fashion the effect PERC has on renal blood flow and renal function. If a
deleterious effect is identified, future efforts can be focused on minimizing this insult.
Inclusion Criteria:
- Patients of Methodist Urology in Indianapolis, IN
- Age greater than 18 years
- Ability to provide informed consent
- Unilateral renal calculi appropriate for percutaneous removal
Exclusion Criteria:
- Age less than 18
- Inability to give informed consent
- Pregnant
- Renal calculi associated with infection
- Serum creatinine > 1.4 mg/dL
- Renal obstruction
- Renal anatomic abnormality precluding accurate functional assessment using nuclear
medicine techniques
- Renal duplication/anatomic abnormality (e.g., horseshoe kidney, malrotation, ectopia,
etc.)
- Pre-existing diuretic therapy
- Solitary functional kidney or suspected significant differential in renal function
- Presence of diabetes, hypertension, or any other systemic disorder or medication
known to affect renal function
- History of urinary tract infection
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