Infection prevention strategies are highly protective in COVID-19 units while main risks to healthcare professionals come from coworkers and the community.

BACKGROUND: Early evaluations of healthcare professional (HCP) COVID-19 risk occurred during insufficient personal protective equipment and disproportionate testing, contributing to perceptions of high patient-care related HCP risk. We evaluated HCP COVID-19 seropositivity after accounting for community factors and coworker outbreaks. METHODS: Prior to universal masking, we conducted a single-center retrospective cohort plus cross-sectional study. All HCP (1) seen by Occupational Health for COVID-like symptoms (regardless of test result) or assigned to (2) dedicated COVID-19 units, (3) units with a COVID-19 HCP outbreak, or (4) control units from 01/01/2020 to 04/15/2020 were offered serologic testing by an FDA-authorized assay plus a research assay against 67 respiratory viruses, including 11 SARS-CoV-2 antigens. Multivariable models assessed the association of demographics, job role, comorbidities, care of a COVID-19 patient, and geocoded socioeconomic status with positive serology. RESULTS: Of 654 participants, 87 (13.3%) were seropositive; among these 60.8% (N = 52) had never cared for a COVID-19 patient. Being male (OR 1.79, CI 1.05-3.04, p = 0.03), working in a unit with a HCP-outbreak unit (OR 2.21, CI 1.28-3.81, p < 0.01), living in a community with low owner-occupied housing (OR = 1.63, CI = 1.00-2.64, p = 0.05), and ethnically Latino (OR 2.10, CI 1.12-3.96, p = 0.02) were positively-associated with COVID-19 seropositivity, while working in dedicated COVID-19 units was negatively-associated (OR 0.53, CI = 0.30-0.94, p = 0.03). The research assay identified 25 additional seropositive individuals (78 [12%] vs. 53 [8%], p < 0.01). CONCLUSIONS: Prior to universal masking, HCP COVID-19 risk was dominated by workplace and community exposures while working in a dedicated COVID-19 unit was protective, suggesting that infection prevention protocols prevent patient-to-HCP transmission. Prior to universal masking, HCP COVID-19 risk was dominated by workplace and community exposures while working in a dedicated COVID-19 unit was protective, suggesting that infection prevention protocols prevent patient-to-HCP transmission.

A multidisciplinary organ donor council and performance improvement initiative can improve donation outcomes.

The shortage of organs available for transplantation has become a national crisis. The Department of Health and Human Services established performance benchmarks for timely notification, donation after cardiac death (DCD), and conversion rates (total donors/eligible deaths) to guide organ procurement organizations and donor hospitals in their attempts to increase the number of transplantable organs. In January 2007, an organ donor council (ODC) with an ongoing performance improvement case review process was created at a Level I trauma center. A critical care devastating brain injury protocol and a DCD policy were instituted. Best performance benchmarks were evaluated before and after establishment of the ODC. At our center, the total number of referrals increased from 96 in 2006 to 139 in 2007 and 143 in 2008. Timely notification rate increased from 64 per cent in 2006 to 83 per cent in 2007 and 2008 (P < 0.01). DCD rate increased from 0 per cent in 2006 to 13 per cent in 2007 (P = 0.06) and 10 per cent in 2008 (P = 0.09). Conversion rate increased from 53 per cent in 2007 to 78 per cent in 2008 (P = 0.05) and 73 per cent in 2009 (P = 0.16). Organs transplanted per eligible death trended upward from 1.80 in 2007 to 2.54 in 2009 (P = 0.20). As a consequence, the establishment of a multidisciplinary ODC and performance improvement initiative demonstrated improved donation outcomes.

Time-course for recovery of renal function after unilateral (single-tract) percutaneous access in the pig.

INTRODUCTION: The immediate (1-5 hours) response to percutaneous renal access (PERC) in pigs is vasoconstriction in the treated kidney. The present study determined the longer-term (72 hours) consequences of this surgical procedure. MATERIALS AND METHODS: Adult female pigs were anesthetized, and bilateral glomerular filtration rate (GFR), effective renal plasma flow (ERPF), urine flow rate, and sodium excretion rate were measured before and 1 hour after sham PERC or unilateral, single-tract PERC using a balloon dilator system. Animals were allowed to regain consciousness and were then anesthetized 72 hours later for final measurements of bilateral renal hemodynamic and excretory function together with renal para-aminohippuric acid (PAH) extraction (a measure of tubular organic anion transport efficiency). RESULTS: Bilateral renal hemodynamics were unchanged in the sham-PERC-treated pigs over the 72-hour observation period. In contrast, both GFR and ERPF were reduced by approximately 55% in the PERC-treated kidney within 1 hour of access, and returned to pre-PERC levels within 72 hours. Renal hemodynamics were not significantly altered in the opposite, untreated kidney of the PERC-treated pigs. Renal PAH extraction was decreased in PERC-treated kidneys at 72 hours post-PERC. Both sham-PERC-treated and PERC-treated animals showed similar falls in urine flow rate and sodium excretion rate immediately after treatment and at 72 hours after PERC. CONCLUSIONS: Renal vasoconstriction characterized the acute response of the treated kidney to unilateral PERC, whereas impaired tubular function (reduced PAH extraction) with near-normal GFR and ERPF characterizes the later (72 hours) response to PERC.

Renal functional effects of multiple-tract percutaneous access.

INTRODUCTION: Percutaneous nephrolithotomy (PCNL) can involve establishing more than one access into the urinary collecting system. The present study examined whether multiple percutaneous accesses results in a more severe reduction in renal function than that after single-percutaneous access. METHODS: Adult female pigs were anesthetized, and percutaneous access to the left urinary collecting system was achieved by puncturing the lower pole calyx (single-tract access, n = 16) or serially puncturing the lower pole, interpolar region, and upper pole calyces [multiple (three)-tract access, n = 11]. Renal function measurements included glomerular filtration rate and effective renal plasma flow, and were taken immediately before and 1.5 and 4.5 hours after percutaneous access. We also examined glomerular function in a group of adult patients with normal preoperative serum creatinine (Cr) levels (

Extracorporeal shock wave lithotripsy at 60 shock waves/min reduces renal injury in a porcine model.

OBJECTIVE: To determine if extracorporeal shock wave lithotripsy (ESWL) at 60 shock waves (SWs)/min reduces renal damage and haemodynamic impairment compared to treatment at 120 SWs/min. MATERIALS AND METHODS: One kidney in each of 19 juvenile pigs (7-8 weeks old) was treated at 120 or at 60 SWs/min (2000 SWs, 24 kV) with an unmodified HM-3 lithotripter (Dornier Medical Systems, Kennesaw, GA, USA). Renal function was determined before and after ESWL treatment by inulin clearance, extraction and clearance of para-aminohippuric acid. Both kidneys were then removed to measure parenchymal lesion size by sectioning the entire kidney and quantifying the size of the haemorrhagic lesion in each slice. RESULTS: ESWL at 60 SWs/min significantly reduced the size of the acute morphological lesion compared to 120 SWs/min (0.42% vs 3.93% of functional renal volume, P = 0.011) and blunted the decrease in glomerular filtration rate and renal plasma flow normally seen after treatment at 120 SWs/min. CONCLUSIONS: Treatment at a firing rate of 60 SWs/min produces less morphological injury and causes less alteration in renal haemodynamics than treatment at 120 SWs/min in the pig model of ESWL-induced renal injury.

Pretreatment with low-energy shock waves induces renal vasoconstriction during standard shock wave lithotripsy (SWL): a treatment protocol known to reduce SWL-induced renal injury.

OBJECTIVE: To test the hypothesis that the pretreatment of the kidney with low-energy shock waves (SWs) will induce renal vasoconstriction sooner than a standard clinical dose of high-energy SWs, thus providing a potential mechanism by which the pretreatment SW lithotripsy (SWL) protocol reduces tissue injury. MATERIALS AND METHODS: Female farm pigs (6-weeks-old) were anaesthetized with isoflurane and the lower pole of the right kidney treated with SWs using a conventional electrohydraulic lithotripter (HM3, Dornier GmbH, Germany). Pulsed Doppler ultrasonography was used to measure renal resistive index (RI) in blood vessels as a measure of resistance/impedance to blood flow. RI was recorded from one intralobar artery located in the targeted pole of the kidney, and measurements taken from pigs given sham SW treatment (Group 1; no SWs, four pigs), a standard clinical dose of high-energy SWs (Group 2; 2000 SWs, 24 kV, 120 SWs/min, seven pigs), low-energy SW pretreatment followed by high-energy SWL (Group 3; 500 SWs, 12 kV, 120 SWs/min + 2000 SWs, 24 kV, 120 SWs/min, eight pigs) and low-energy SW pretreatment alone (Group 4; 500 SWs, 12 kV, 120 SWs/min, six pigs). RESULTS: Baseline RI (approximately 0.61) was similar for all groups. Pigs receiving sham SW treatment (Group 1) had no significant change in RI. A standard clinical dose of high-energy SWs (Group 2) did not significantly alter RI during treatment, but did increase RI at 45 min after SWL. Low-energy SWs did not alter RI in Group 3 pigs, but subsequent treatment with a standard clinical dose of high-energy SWs resulted in a significantly earlier (at 1000 SWs) and greater (two-fold) rise in RI than that in Group 2 pigs. This rise in RI during the low/high-energy SWL protocol was not due to a delayed vasoconstrictor response of pretreatment, as low-energy SW treatment alone (Group 4) did not increase RI until 65 min after SWL. CONCLUSIONS: The pretreatment protocol induces renal vasoconstriction during the period of SW application whereas the standard protocol shows vasoconstriction occurring after SWL. Thus, the earlier and greater rise in RI during the pretreatment protocol may be causally associated with a reduction in tissue injury.

Localization of renal oxidative stress and inflammatory response after lithotripsy.

OBJECTIVE To determine if the acute renal oxidative stress and inflammation after extracorporeal shock wave lithotripsy (ESWL), thought to be mediated by ischaemia, is most severe in the portion of the kidney within the focal zone of the lithotripter, and if these effects result primarily from ischaemic injury. MATERIALS AND METHODS Pigs (7-8-weeks old) received either 2000 shock waves at 24 kV to the lower-pole calyx of one kidney or unilateral renal ischaemia for 1 h. A third group (sham) received no treatment. Timed urine and blood samples were taken for analysis of lipid peroxidation and the inflammatory cytokines, tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). At 4 h after treatment, kidneys were removed and samples of cortex and medulla were frozen for analysis of cytokines and heme oxygenase-1 (HO-1). RESULTS ESWL did not affect urinary excretion of malondialdehyde, but did elicit an eight-fold induction of HO-1 in the portion of the renal medulla within the focal zone of the lithotripter (F2), while remaining unchanged elsewhere in the treated kidney. There was no induction of HO-1 in renal tissue after ischaemia-reperfusion. Urinary excretion of TNF-alpha increased from the lithotripsy-treated kidney by 1 h after treatment, but was unaffected by ischaemia-reperfusion. As with the HO-1 response after lithotripsy, IL-6 increased only in the renal medulla at F2. By contrast, ischaemia-reperfusion increased IL-6 in all samples from the treated kidney. CONCLUSION These findings show that the acute oxidative stress and inflammatory responses to ESWL are localized to the renal medulla at F2. Furthermore, the differing patterns of markers of injury for ESWL and ischaemia-reperfusion suggest that ischaemia is not the principal cause of the injury response after ESWL.

Effect of initial shock wave voltage on shock wave lithotripsy-induced lesion size during step-wise voltage ramping.

OBJECTIVE: To determine if the starting voltage in a step-wise ramping protocol for extracorporeal shock wave lithotripsy (SWL) alters the size of the renal lesion caused by the SWs. MATERIALS AND METHODS: To address this question, one kidney from 19 juvenile pigs (aged 7-8 weeks) was treated in an unmodified Dornier HM-3 lithotripter (Dornier Medical Systems, Kennesaw, GA, USA) with either 2000 SWs at 24 kV (standard clinical treatment, 120 SWs/min), 100 SWs at 18 kV followed by 2000 SWs at 24 kV or 100 SWs at 24 kV followed by 2000 SWs at 24 kV. The latter protocols included a 3-4 min interval, between the 100 SWs and the 2000 SWs, used to check the targeting of the focal zone. The kidneys were removed at the end of the experiment so that lesion size could be determined by sectioning the entire kidney and quantifying the amount of haemorrhage in each slice. The average parenchymal lesion for each pig was then determined and a group mean was calculated. RESULTS: Kidneys that received the standard clinical treatment had a mean (sem) lesion size of 3.93 (1.29)% functional renal volume (FRV). The mean lesion size for the 18 kV ramping group was 0.09 (0.01)% FRV, while lesion size for the 24 kV ramping group was 0.51 (0.14)% FRV. The lesion size for both of these groups was significantly smaller than the lesion size in the standard clinical treatment group. CONCLUSIONS: The data suggest that initial voltage in a voltage-ramping protocol does not correlate with renal damage. While voltage ramping does reduce injury when compared with SWL with no voltage ramping, starting at low or high voltage produces lesions of the same approximate size. Our findings also suggest that the interval between the initial shocks and the clinical dose of SWs, in our one-step ramping protocol, is important for protecting the kidney against injury.

Evidence for increased postprandial distal nephron calcium delivery in hypercalciuric stone-forming patients.

A main mechanism of idiopathic hypercalciuria (IH) in calcium stone-forming patients (IHSF) is postprandial reduction of renal tubule calcium reabsorption that cannot be explained by selective reduction of serum parathyroid hormone levels; the nephron site(s) responsible are not as yet defined. Using fourteen 1-h measurements of the clearances of sodium, calcium, and endogenous lithium during a three-meal day in the University of Chicago General Clinical Research Center, we found reduced postprandial proximal tubule reabsorption of sodium and calcium in IHSF vs. normal subjects. The increased distal sodium delivery is matched by increased distal reabsorption so that urine sodium excretions do not differ, but distal calcium reabsorption does not increase enough to match increased calcium delivery, so hypercalciuria results. In fact, urine calcium excretion and overall renal fractional calcium reabsorption both are high in IHSF vs. normal when adjusted for distal calcium delivery, strongly suggesting a distal as well as proximal reduction of calcium reabsorption. The combination of reduced proximal tubule and distal nephron calcium reabsorption in IHSF is a new finding and indicates that IH involves a complex, presumably genetic, variation of nephron function. The increased calcium delivery into the later nephron may play a role in stone formation via deposition of papillary interstitial apatite plaque.

Potential for cavitation-mediated tissue damage in shockwave lithotripsy.

PURPOSE: Shockwave lithotripsy (SWL) injures renal tissue, and cavitation has been reported to mediate some of these effects. Much of the work characterizing the cavitation injury of SWL has been performed in small animals or in vitro. We describe experiments that promote cavitation during SWL and estimate the spatial distribution of the resulting hemorrhagic lesion in a large-animal (porcine) model of clinical lithotripsy. MATERIALS AND METHODS: The lower pole calix of the left kidney in female farm pigs was targeted for SWL with a Dornier HM3 lithotripter. Intraventricular injections of polystyrene microspheres were made before and at intervals during lithotripsy to blanket systemic circulation with cavitation nuclei. Following SWL, the abdominal viscera were inspected and the kidneys were processed for morphologic analysis. RESULTS: Extensive surface hemorrhage occurred over both the targeted and contralateral kidneys, along with widespread petechial hemorrhage over the spleen, intestines, and peritoneum. The targeted kidneys developed subcapsular hematomas. Histology revealed focal and diffuse damage to the targeted kidneys and vascular rupture in both kidneys with complete necrosis of the walls of intralobular arteries and veins. CONCLUSIONS: These results demonstrate the potential for unfocused shockwaves to damage blood vessels outside the focal zone of the lithotripter when the vasculature is seeded with cavitation nuclei. The wide distribution of damage suggests that the acoustic field of a lithotripter delivers negative pressures that exceed the cavitation threshold far off the acoustic axis. The findings underscore that conditions permissive for cavitation can lead to dramatic sequelae during SWL.

Independent assessment of a wide-focus, low-pressure electromagnetic lithotripter: absence of renal bioeffects in the pig.

OBJECTIVE: To assess the renal injury response in a pig model treated with a clinical dose of shock waves (SWs) delivered at a slow rate (27 SW/min) using a novel wide focal zone (18 mm), low acoustic pressure (<20 MPa) electromagnetic lithotripter (Xi Xin-Eisenmenger, XX-ES; Xi Xin Medical Instruments Co. Ltd., Suzhou, PRC). MATERIALS AND METHODS: The left kidneys of anaesthetized female pigs were treated with 1500 SWs from either an unmodified electrohydraulic lithotripter (HM3, Dornier MedTech America, Inc., Kennesaw, GA, USA; 18 kV, 30 SW/min) or the XX-ES (9.3 kV, 27 SW/min). Measures of renal function (glomerular filtration rate, GFR, and renal plasma flow) were collected before and after SW lithotripsy, and kidneys were harvested for histological quantification of vascular haemorrhage, expressed as a percentage of the functional renal volume (FRV). A fibre-optic probe hydrophone was used to characterize the acoustic field, and the breakage of gypsum model stones was used to compare the function of the two lithotripters. RESULTS: Kidneys treated with the XX-ES showed no significant change in renal haemodynamic function and no detectable tissue injury. Pigs treated with the HM3 had a modest decline from baseline ( approximately 20%) in both GFR (P > 0.05) and renal plasma flow (P = 0.064) in the treated kidney, but that was not significantly different from the control group. Although most HM3-treated pigs showed no evidence of renal tissue injury, two had focal injury measuring 0.1% FRV, localized to the renal papillae. The width of the focal zone for the XX-ES was approximately 18 mm and that of the HM3 approximately 8 mm. Peak positive pressures at settings used to treat pigs and break model stones were considerably lower for the XX-ES (17 MPa at 9.3 kV) than for the HM3 (37 MPa at 18 kV). The XX-ES required fewer SWs to break stones to completion than did the HM3, with a mean (sd) of 634 (42) and 831 (43) SWs, respectively (P < 0.01). However, conditions were different for these tests because of differences in physical configuration of the two machines. CONCLUSION: The absence of renal injury with the wide focal zone XX-ES lithotripter operated at low shock pressure and a slow SW rate suggests that this lithotripter would be safe when used at the settings recommended for patient treatment. That the injury was also minimal using the Dornier HM3 lithotripter at a slow SW rate implies that the reduced tissue injury seen with these two machines was because they were operated at a slow SW rate. As recent studies have shown stone breakage to be improved when the focal zone is wider than the stone, a wide focal zone lithotripter operated at low pressure and slow rate has the features necessary to provide better stone breakage with less tissue injury.

Assessment of Cu-ETS as a PET radiopharmaceutical for evaluation of regional renal perfusion.

UNLABELLED: The copper(II) complex of ethylglyoxal bis(thiosemicarbazone) (Cu-ETS) was evaluated as a positron emission tomography (PET) radiopharmaceutical for assessment of regional renal perfusion. METHODS: The concordance of renal flow estimates obtained with 11- and 15-microm microspheres was confirmed in four immature farm pigs using co-injected (46)Sc- and (57)Co-microspheres administered into the left ventricle. With the use of both immature farm pigs (n=3) and mature Göttingen minipigs (n=6), regional renal radiocopper uptake following intravenous [(64)Cu]Cu-ETS administration was compared to microsphere measurements of renal perfusion. The distribution and kinetics of [(64)Cu]Cu-ETS were further studied by PET imaging of the kidneys. The rate of [(64)Cu]Cu-ETS decomposition by blood was evaluated in vitro, employing octanol extraction to recover intact [(64)Cu]Cu-ETS. RESULTS: The co-injected 11- and 15-microm microspheres provided similar estimates of renal flow. A linear relationship was observed between the renal uptake of intravenous [(64)Cu]Cu-ETS and regional renal perfusion measured using microspheres. [(64)Cu]Cu-ETS provided high-quality PET kidney images demonstrating the expected count gradient from high-flow outer cortex to low-flow medulla. When incubated with pig blood in vitro at 37 degrees C, the [(64)Cu]Cu-ETS radiopharmaceutical was observed to decompose with a half-time of 2.8 min. CONCLUSION: Cu-ETS appears suitable for use as a PET radiopharmaceutical for evaluation of regional renal perfusion, affording renal uptake of radiocopper that varies linearly with microsphere perfusion measurements. Quantification of renal perfusion (in ml min(-1) g(-1)) with [(60,61,62,64)Cu]Cu-ETS will require correcting the arterial input function for the fraction of blood radiocopper remaining present as the intact Cu-ETS radiopharmaceutical, since the Cu-ETS chelate has limited chemical stability in blood. Rapid octanol extraction of blood samples appears suitable as an approach to capturing the actual blood concentration of [(60/61/62/64)Cu]Cu-ETS.

Dual-head lithotripsy in synchronous mode: acute effect on renal function and morphology in the pig.

OBJECTIVE: To assess the effect of dual-head lithotripsy on renal function and morphology in a pig model of shockwave (SW) injury, as lithotripters with two shock heads are now available for treating patients, but little information is available with which to judge the safety of treatment with dual pulses. MATERIALS AND METHODS: A dual-head electrohydraulic lithotripter (Duet, Direx Corp., Natick, MA, USA) was used to treat the lower renal pole of anaesthetized pigs with a clinical dose of SWs (2400 dual SWs; 10 kidneys) delivered in synchronous mode, i.e. both heads fired simultaneously. For comparison, pigs were treated with either 2400 SWs (12 kidneys) or 4800 SWs (eight) with a conventional electrohydraulic lithotripter (HM3, Dornier, Wessling, Germany). RESULTS: Dual-pulse SW treatment with the Duet lithotripter caused a decline in the mean (sd) glomerular filtration rate (GFR) of 4.1 (1.9) mL/min, with a trend for the effective renal plasma flow (RPF), at 31 (19) mL/min, to also decrease. These changes in renal haemodynamics were similar to the decreases in GFR and RPF in response to treatment with the HM3 lithotripter with 2400 SWs, at 4.8 (0.8) and 32 (10) mL/min, respectively, or 4800 SWs, at 5.4 (1.0) and 68 (14) mL/min, respectively. Linear association analysis showed that the functional response to dual-pulse SWs was more variable than with conventional SWs. Morphological quantification of kidney damage (expressed as a percentage of functional renal volume, FRV) showed that tissue injury with 2400 paired SWs with the Duet, at 0.96 (0.39)% FRV, was similar to injury produced by either 2400 single SWs, at 1.08 (0.38)% FRV, or 4800 single SWs, at 2.71 (1.02)% FRV, with the HM3. However, morphological damage was less consistent with the Duet (measurable in only five of eight kidneys) than that with the HM3 (measurable in all 12 kidneys). Acoustic output and the timing of dual SWs in synchronous mode increased in variability as the electrodes aged, affecting the amplitude and targeting of focal pressures. CONCLUSION: With the caveat that variability in the timing of dual SWs will unpredictably alter the distribution of SW energy within the kidney, this study shows that a clinical dose of dual-head SWs delivered in synchronous mode elicits a renal response similar to, but more variable than, that with a clinical dose of SWs from a conventional electrohydraulic lithotripter.

Reducing shock number dramatically decreases lesion size in a juvenile kidney model.

BACKGROUND AND PURPOSE: Adult stone patients are treated with several thousand lithotripter shockwaves (SWs) in order to pulverize a kidney stone. This typical clinical dose assures that the stone will be fractured completely. However, this same dose induces damage to the kidney, especially pediatric-size kidneys. If increasing SW number is known to increase renal injury and functional impairment, will reducing SW number below typical treatment levels significantly decrease kidney damage and hemodynamic changes? MATERIALS AND METHODS: To address this question, one kidney in each of nine juvenile pigs (6-7 weeks old) was treated with 1000 SWs at 24 kV directed at a lower-pole calix with an unmodified HM-3 lithotripter. Parenchymal-lesion size was determined by sectioning the entire kidney and quantitating the amount of hemorrhage in each slice. Renal function was determined before and after SW treatment by inulin clearance, paraaminohippurate (PAH) extraction, and PAH clearance. The resulting morphologic and functional changes were then compared with those of kidneys that had been treated with a typical clinical dose of 2000 SWs (data previously published; J Am Soc Nephrol 2000;11:310). Eleven pigs were utilized as sham-treated controls. RESULTS: Limiting SW number to 1000 significantly reduced the size of the lesion (by 95%) and reduced the degree of functional change (glomerular filtration rate by 38%, PAH extraction by 73%, renal plasma flow by 46%) compared with kidneys receiving 2000 SWs (an adult dose). CONCLUSIONS: These data support the idea that SW number should be reduced to the lowest number that fractures kidney stones in order to minimize renal injury and functional impairment.

Prevention of lithotripsy-induced renal injury by pretreating kidneys with low-energy shock waves.

Lithotripsy shock waves (SW) to one renal pole damage that pole but protect the opposite pole from the damage inflicted by another, immediate application of SW. This study investigated whether the protection (1) occurs when the first treatment causes no injury, (2) is caused by SW or injury, (3) exhibits a threshold, and (4) occurs when the same pole receives both treatments. Six- to 7-wk-old anesthetized female pigs were studied. The following groups were studied: group 1 (n=4), 2000 SW at 12 kV to one pole and 2000 SW at 24 kV (standard) to the opposite pole; group 2 (n=6), same as group 1 except 500 12-kV SW pretreatment; group 3 (n=8), 500 12-kV, 2000 standard SW, all to the same pole; and group 4 (n=8), same as group 3 except 100 12-kV SW pretreatment. Mean+/-SD lesion size in group 1, first pole treated, was 0.66+/-0.82% of functional renal volume (FRV; P<0.05 versus 5.22+/-3.6% FRV with no pretreatment [NP]; 95% confidence interval [CI] -7.0 to -2.1) and 0.50+/-0.68% FRV in the opposite pole after 2000 standard SW (P<0.05 versus NP; 95% CI -9.4 to -0.08). Mean lesion size (first pole) in group 2 was 0.020+/-0.028% FRV (P<0.01 versus NP; 95% CI -9.2 to -1.2) and 0.43+/-0.54% FRV in the opposite pole after 2000 standard SW (P<0.05 versus NP; 95% CI -8.8 to -0.82). Same-pole SW (groups 3 and 4) also protected. Mean lesion sizes were 0.28+/-0.33% (P<0.01 versus NP; 95% CI -8.0 to -1.9) in group 3 and 0.39+/-0.48% FRV (P<0.01 versus NP; 95% CI -8.2 to -1.7) in group 4. It is concluded that the pretreatment protocol substantially limits the renal injury that normally is caused by SWL and occurs when the pretreatment and standard SW are applied to the same pole. The threshold for the protection may be <100 SW.

Acute effects of percutaneous tract dilation on renal function and structure.

BACKGROUND: Percutaneous nephrolithotomy (PCNL) is performed on a routine basis for the rapid and efficient removal of large caliceal stones. After percutaneous puncture, rigid dilators or an inflatable balloon are used to dilate the nephrostomy tract to allow access to the collecting system for stone removal. Little is known of the acute impact of tract dilation procedures on renal function. MATERIALS AND METHODS: We compared renal hemodynamic and excretory function in female pigs immediately before and up to 5 hours after percutaneous nephrostomy (PCN) using sequential Amplatz dilators (N = 8) or Nephromax balloon inflation (N = 7) and control pigs with no PCN access (N = 8). We also examined renal function in patients undergoing PCNL. RESULTS: The two PCN procedures produced a renal lesion of comparable size and morphology, as well as similar changes in renal function. Glomerular filtration rate (GFR), renal plasma flow (RPF), and urinary sodium excretion (U(Na)V) were significantly reduced in Amplatz- and Nephromax-treated kidneys throughout the 5-hour observation period, by about 50%, 60%, and 80%, respectively. In control pigs, GFR and RPF remained stable and U(Na)V declined progressively to about 50% of baseline over the course of the experiment. The contralateral kidney showed changes in renal function similar to those in the PCN-treated or control kidney in all three groups. A retrospective analysis of 196 adults with normal renal function who underwent unilateral PCNL using the Nephromax balloon dilator revealed a significant increase in serum creatinine of 0.14 mg/dL at 1 day. CONCLUSION: Both animal and human studies show that PCN is associated with an acute decline in renal function.

Shockwave lithotripsy: dose-related effects on renal structure, hemodynamics, and tubular function.

BACKGROUND AND PURPOSE: Shockwave lithotripsy (SWL) predictably damages renal tissue and transiently reduces function in both kidneys. This study characterized the effects on renal function of a supraclinical dose of shockwaves (SWs) (8000) in porcine kidneys and tested the hypothesis that such excessive treatment would intensify and prolong the resulting renal impairment. MATERIALS AND METHODS: Pigs aged 6 to 7 weeks were anesthetized and assigned to one of three groups. Groups 1 (N=8) and 2 (N=6) each received 8000 SWs at 24 kV (Dornier HM3) to the lower-pole calix of one kidney. Group 3 (7 pigs) received sham treatment. Renal function was monitored for the first 4 hours after SW treatment in Group 1 and for 24 hours in Group 2. Plasma renin activity was measured in Groups 2 and 3. RESULTS: The renal lesions produced by 8000 SWs comprised 13.8%+/-1.4% of the renal mass. In the 4-hour protocol, this injury was associated with marked reduction of the glomerular filtration rate (GFR), renal plasma flow (RPF), and urinary sodium excretion in both kidneys, although fractional sodium excretion was reduced only in the shocked kidneys. In the 24-hour protocol, GFR and RPF remained below baseline in shocked kidneys at 24 hours. Evidence of progressive ischemic injury was noted in shocked tissue at 24 hours after SW treatment. CONCLUSIONS: These findings support the hypothesis that the severity of the renal injury caused by SWL is related to the number of SWs administered and demonstrate the connection in this relation between renal structure and function.

Developing an OSTE to address lapses in learners' professional behavior and an instrument to code educators' responses.

PURPOSE: To develop an instrument for measuring medical educators' responses to learners' lapses in professional behavior. METHOD: In 1999, at the Indiana University School of Medicine, a 22-item checklist of behaviors was developed to describe common responses used by educators responding to learners' lapses in professional behavior. Four medical students were trained to portray lapses in professional behaviors. These students and seven clinical observers trained to categorize behaviors as present or absent. Interrater reliability was assessed during 18 objective structured teaching evaluations (OSTEs). Videotaped OSTEs were coded twice at a one-month interval for test-retest reliability. Items were classified as low, moderate, or high inference behaviors. Script realism and educator effectiveness were assessed. RESULTS: Educators rated OSTE scripts as realistic. Raters observed an average of 6 +/- 2 educator behaviors in reaction to learners' lapses in professional behavior. Educators' responses were rated as moderately effective. More experienced educators attempted more interventions and were more effective. Agreement was high among raters (86% +/- 7%), while intraclass correlation coefficients decreased with increasing inference level. From videotaped OSTEs, raters scored each behavior identically 86% of the time. CONCLUSIONS: Accurate feedback on educators' interactions in addressing learners' professionalism is essential for faculty development. Traditionally, educators have felt that faculty's responses to learners' lapses in professional behavior were difficult to observe and categorize. These data suggest that educators' responses to learners' lapses in professional behavior can be defined and reliably coded. This work will help provide objective feedback to faculty when engaging learners about lapses in professional behavior.

Renal nerves mediate changes in contralateral renal blood flow after extracorporeal shockwave lithotripsy.

Renal blood flow falls in both kidneys following delivery of a clinical dose of shockwaves (SW) (2000 SW, 24 kV, Dornier HM3) to only one kidney. The role of renal nerves in this response was examined in a porcine model of renal denervation. Six-week-old pigs underwent unilateral renal denervation. Nerves along the renal artery of one kidney were identified, sectioned and painted with 10% phenol. Two weeks later the pigs were anesthetized and baseline renal function was determined using inulin and PAH clearances. Animals then had either sham-shockwave lithotripsy (SWL) (group 1), SWL to the innervated kidney (group 2) or SWL to the denervated kidney (group 3). Bilateral renal function was again measured 1 and 4 h after SWL. Both kidneys were then removed for analysis of norepinephrine content to validate the denervation. Renal plasma (RPF) flow was significantly reduced in shocked innervated kidneys (group 2) and shocked denervated kidneys (group 3). RPF was not reduced in the unshocked denervated kidneys of group 2. These observations suggest that renal nerves play a pivotal role in modulating the vascular response of the contralateral unshocked kidney to SWL, but only a partial role, if any, in modulating that response in the shocked kidney.

Morphological changes induced in the pig kidney by extracorporeal shock wave lithotripsy: nephron injury.

While shock wave lithotripsy (SWL) is known to cause significant damage to the kidney, little is known about the initial injury to cells along the nephron. In this study, one kidney in each of six juvenile pigs (6-7 weeks old) was treated with 1,000 shock waves (at 24 kV) directed at a lower pole calyx with an unmodified HM-3 lithotripter. Three pigs were utilized as sham-controls. Kidneys were fixed by vascular perfusion immediately after SWL or sham-SWL. Three of the treated kidneys were used to quantitate lesion size. Cortical and medullary samples for light (LM) and transmission electron microscopy (TEM) were taken from the focal zone for the shock waves (F2), the contralateral kidney, and the kidneys of sham-SWL pigs. Because preservation of the tissue occurred within minutes of SWL, the initial injury caused by the shock waves could be separated from secondary changes. No tissue damage was observed in contralateral sham-SWL kidneys, but treated kidneys showed signs of injury, with a lesion of 0.2% +/- 0.1% of renal volume. Intraparenchymal hemorrhage and injury to tubules was found at F2 in both the cortex and medulla of SWL-treated kidneys. Tubular injury was always associated with intraparenchymal bleeding, and the range of tissue injury included total destruction of tubules, focal cellular fragmentation, necrosis, cell vacuolization, and membrane blebbing. The initial injury caused by SWL was cellular fragmentation and necrosis. Cellular vacuolization, membrane blebbing, and disorganization of apical brush borders appear to be secondary changes related to hypoxia.