The relationship of peritubular capillary density with glomerular volume and kidney function in living kidney donors

BACKGROUND

Peritubular capillary rarefaction plays an important role in the progression of chronic kidney disease. Little is known about the relation between peritubular capillary density, glomerular volume and filtration rate in the healthy kidney.

METHODS

In this single-center study, we included 69 living kidney donors who donated between 2005 and 2008 and had representative renal biopsies available. In all donors, glomerular filtration rate was measured using 125I-Iothalamate before donation and at five years after donation. Before donation, the increase in glomerular filtration rate after dopamine stimulation was measured. Glomerular volume and peritubular capillary density were determined in biopsies taken at the time of transplantation. Pearson's correlation coefficient and linear regression were used to assess relations between parameters.

RESULTS

Mean donor age was 52 ± 11 years and mean measured glomerular filtration rate was 119 ± 22 mL/min before donation and 82 ± 15 mL/min at five years after donation. While peritubular capillary density (measured by either number of peritubular capillaries/50,000 μm2 or number of peritubular capillaries/tubule) was not associated with measured glomerular filtration rate before or after donation, number of peritubular capillaries/tubule was associated with the increase in measured glomerular filtration rate after dopamine stimulation (St.β = 0.33, p = 0.004), and correlated positively with glomerular volume (R = 0.24, p = 0.047). Glomerular volume was associated with unstimulated measured glomerular filtration rate before donation (St.β = 0.31, p = 0.01) and at five years (St.β = 0.30, p = 0.01) after donation, independent of age.

CONCLUSIONS

In summary, peritubular capillary density was not related to unstimulated kidney function before or after kidney donation, in contrast to glomerular volume. However, number of peritubular capillaries/tubule correlated with the increase in glomerular filtration rate after dopamine stimulation in healthy kidneys, and with glomerular volume. These findings suggest that peritubular capillary density and glomerular volume differentially affect kidney function in healthy living kidney donors.

Editor's Choice - Nationwide Analysis of Patients Undergoing Iliac Artery Aneurysm Repair in the Netherlands

OBJECTIVE

The new 2019 guideline of the European Society for Vascular Surgery (ESVS) recommends consideration for elective iliac artery aneurysm (eIAA) repair when the iliac diameter exceeds 3.5 cm, as opposed to 3.0 cm previously. The current study assessed diameters at time of eIAA repair and ruptured IAA (rIAA) repair and compared clinical outcomes after open surgical repair (OSR) and endovascular aneurysm repair (EVAR).

METHODS

This retrospective observational study used the nationwide Dutch Surgical Aneurysm Audit (DSAA) registry that includes all patients who undergo aorto-iliac aneurysm repair in the Netherlands. All patients who underwent primary IAA repair between 1 January 2014 and 1 January 2018 were included. Diameters at time of eIAA and rIAA repair were compared in a descriptive fashion. The anatomical location of the IAA was not registered in the registry. Patient characteristics and outcomes of OSR and EVAR were compared with appropriate statistical tests.

RESULTS

The DSAA registry comprised 974 patients who underwent IAA repair. A total of 851 patients were included after exclusion of patients undergoing revision surgery and patients with missing essential variables. eIAA repair was carried out in 713 patients, rIAA repair in 102, and symptomatic IAA repair in 36. OSR was performed in 205, EVAR in 618, and hybrid repairs and conversions in 28. The median maximum IAA diameter at the time of eIAA and rIAA repair was 43 (IQR 38-50) mm and 68 (IQR 58-85) mm, respectively. Mortality was 1.3% (95% CI 0.7-2.4) after eIAA repair and 25.5% (95% CI 18.0-34.7) after rIAA repair. Mortality was not significantly different between the OSR and EVAR subgroups. Elective OSR was associated with significantly more complications than EVAR (intra-operative: 9.8% vs. 3.6%, post-operative: 34.0% vs. 13.8%, respectively).

CONCLUSION

In the Netherlands, most eIAA repairs are performed at diameters larger than recommended by the ESVS guideline. These findings appear to support the recent increase in the threshold diameter for eIAA repair.

Risk of anastomotic leakage with non-steroidal anti-inflammatory drugs in colorectal surgery

BACKGROUND

With the implementation of multimodal analgesia regimens in fast-track surgery programmes, non-steroidal anti-inflammatory drugs (NSAIDs) are being prescribed routinely. However, doubts have been raised concerning the safety of NSAIDs in terms of anastomotic healing.

METHODS

Data on patients who had undergone primary colorectal anastomosis at two teaching hospitals between January 2008 and December 2010 were analysed retrospectively. Exact use of NSAIDs was recorded. Rates of anastomotic leakage were compared between groups and corrected for known risk factors in both univariable and multivariable analyses.

RESULTS

A total of 795 patients were divided into four groups according to NSAID use: no NSAIDs (471 patients), use of non-selective NSAIDs (201), use of selective cyclo-oxygenase (COX) 2 inhibitors (79), and use of both selective and non-selective NSAIDs (44). The overall leak rate was 9.9 per cent (10.0 per cent for right colonic, 8.7 per cent for left colonic and 12.4 per cent for rectal anastomoses). Known risk factors such as smoking and use of steroids were not significantly associated with anastomotic leakage. Stapled anastomosis was identified as an independent predictor of leakage in multivariable analysis (odds ratio (OR) 2.22, 95 per cent confidence interval 1.30 to 3.80; P = 0.003). Patients on NSAIDs had higher anastomotic leakage rates than those not on NSAIDs (13.2 versus 7.6 per cent; OR 1.84, 1.13 to 2.98; P = 0.010). This effect was mainly due to non-selective NSAIDs (14.5 per cent; OR 2.13, 1.24 to 3.65; P = 0.006), not selective COX-2 inhibitors (9 per cent; OR 1.16, 0.49 to 2.75; P = 0.741). The overall mortality rate was 4.2 per cent, with no significant difference between groups (P = 0.438).

CONCLUSION

Non-selective NSAIDs may be associated with anastomotic leakage.

Renovascular resistance of machine-perfused DCD kidneys is associated with primary nonfunction

Donation after cardiac death (DCD) has shown to be a valuable extension of the donor pool despite a higher percentage of primary nonfunction (PNF). Limiting the incidence of PNF is of vital importance. Renovascular resistance is believed to predict graft outcome; however the literature is inconsistent. Therefore, we studied whether renovascular resistance is associated with PNF and whether this parameter should be used to discard donor kidneys. All transplanted DCD kidneys preserved by machine perfusion at our center between 1993 and 2007 were analyzed (n = 440). The effects of renovascular resistance on PNF, delayed graft function (DGF), and graft and patient survival were examined using multivariable analyses; predictive quality by calculating the area under the curve (AUC). We showed that renovascular resistance at the start of machine perfusion was significantly and independently associated with PNF (OR 2.040, 95% CI 1.362-3.056; p = 0.001), and DGF (OR 2.345, 95% CI 1.110-4.955; p = 0.025). Predictive quality was moderate (0.609, 95% CI 0.538-0.681). Graft and patient survival were not associated with renovascular resistance. We conclude that renovascular resistance in DCD kidneys is an independent risk factor for PNF; however, the predictive value is relatively low.