Objective

Regional citrate anticoagulation (RCA) is the preferred anticoagulation method for continuous kidney replacement therapy (CKRT) recommended by KDIGO. Limited availability of calcium-free solutions often imposes challenges to the implementation of RCA for CKRT (RCA-CKRT). The principal purpose of this study was to characterize the outcomes of RCA-CKRT using calcium-containing solutions.

Study design

Retrospective cohort study.

Setting & participants

We evaluated the safety and efficacy of RCA-CKRT with calcium-containing dialysate and replacement fluid used for 128 patients. A total of 571 filters and 1,227 days of CKRT were analyzed.

Exposures

Liver disease, sepsis in the absence of liver disease, and sepsis with liver disease.

Outcomes

Filter life and metabolic complications per 100 CKRT days.

Analytical approach

Linear mixed-effects model and generalized linear mixed-effects models.

Results

The majority of patients were male (91; 71.1%), 32 (25%) had liver disease, and 29 (22.7%) had sepsis without liver disease. Median filter life was 50.0 (interquartile range, 22.0-118.0) hours, with a maximum of 322 hours, and was significantly lower (33.5 [interquartile range, 17.5-60.5] h) in patients with liver disease. Calcium-containing replacement solutions were used in 41.6% of all CKRT hours and reduced intravenous calcium requirements by 31.7%. Hypocalcemia (ionized calcium<0.85mmol/L) and hypercalcemia (total calcium>10.6mg/dL) were observed in 6.0 and 6.7 per 100 CKRT days, respectively. Citrate accumulation was observed in 13.3% of all patients and was associated with metabolic acidosis in 3.9%, which was not significantly different in patients with liver disease (9.3%; P = 0.2).

Limitations

Lack of control groups that used calcium-free dialysate and replacement solutions with RCA-CKRT. Possible overestimation of filter life from incomplete data on cause of filter failure.

Conclusions

Our study suggests that RCA-CKRT with calcium-containing solutions is feasible and safe in critically ill patients, including those with sepsis and liver disease.

Background

We recently reported on the enhanced tubular expression of two discrete isoforms of the MMP-2 (full length and N-terminal truncated, FL-MMP-2, NTT-MMP-2) in a murine model and human diabetic kidneys. In the present study, we examined in more detail the temporal and spatial distributions of MMP-2 isoform expression in murine models of Type 1 and Type 2 diabetes mellitus.

Methods

Diabetic models were streptozotocin (STZ)-induced diabetes (Type 1 diabetes mellitus) and db/db mice (Type 2 diabetes mellitus). We quantified the abundance of two isoforms of MMP-2 transcripts by qPCR. A spatial distribution of two isoforms of MMP-2 was analyzed semi-quantitatively according to time after injection of STZ and with increasing age of db/db mice. Furthermore, immunohistochemistry for nitrotyrosine was performed to examine a potential association between oxidative stress and MMP-2 isoform expression.

Results

Both isoforms of MMP-2 were upregulated in whole kidneys from STZ and db/db mice. In the case of FL-MMP-2, mRNA levels significantly increased at 12 and 24 weeks in STZ mice, while the isoform expression was significantly increased only at 16 weeks, in the db/db mice. FL-MMP-2 protein levels increased in the cortices and outer medullae of both STZ and db/db mice as a function of the duration of diabetes. For NTT-MMP-2, mRNA levels increased earlier at 4 weeks in STZ mice and at 10 weeks of age in db/db mice. The expression of NTT-MMP-2 also increased, primarily in the cortices of STZ and db/db mice, as a function of the duration of diabetes. Quantitatively, these findings were consistent with the qPCR results in the case of NTT-MMP-2, respectively (STZ 24 weeks, 3.24 ± 3.70 fold; 16 weeks db/db, 4.49 ± 0.55 fold). In addition, nitrotyrosine was expressed primarily in cortex as compared to medulla as a function of the duration of diabetes similar to NTT-MMP-2 expression.

Conclusions

Two isoforms of MMP-2 are highly inducible in two diabetic murine models and become more abundant as a function of time. As the expression patterns were not the same in the two isoforms of MMP-2, it is possible that each isoform has a discrete role in the development of diabetic renal injury.

Rationale & objective

Underlying kidney disease is an emerging risk factor for more severe coronavirus disease 2019 (COVID-19) illness. We examined the clinical courses of critically ill COVID-19 patients with and without pre-existing chronic kidney disease (CKD) and investigated the association between the degree of underlying kidney disease and in-hospital outcomes.

Study design

Retrospective cohort study.

Settings & participants

4,264 critically ill patients with COVID-19 (143 patients with pre-existing kidney failure receiving maintenance dialysis; 521 patients with pre-existing non-dialysis-dependent CKD; and 3,600 patients without pre-existing CKD) admitted to intensive care units (ICUs) at 68 hospitals across the United States.

Predictor(s)

Presence (vs absence) of pre-existing kidney disease.

Outcome(s)

In-hospital mortality (primary); respiratory failure, shock, ventricular arrhythmia/cardiac arrest, thromboembolic events, major bleeds, and acute liver injury (secondary).

Analytical approach

We used standardized differences to compare patient characteristics (values>0.10 indicate a meaningful difference between groups) and multivariable-adjusted Fine and Gray survival models to examine outcome associations.

Results

Dialysis patients had a shorter time from symptom onset to ICU admission compared to other groups (median of 4 [IQR, 2-9] days for maintenance dialysis patients; 7 [IQR, 3-10] days for non-dialysis-dependent CKD patients; and 7 [IQR, 4-10] days for patients without pre-existing CKD). More dialysis patients (25%) reported altered mental status than those with non-dialysis-dependent CKD (20%; standardized difference=0.12) and those without pre-existing CKD (12%; standardized difference=0.36). Half of dialysis and non-dialysis-dependent CKD patients died within 28 days of ICU admission versus 35% of patients without pre-existing CKD. Compared to patients without pre-existing CKD, dialysis patients had higher risk for 28-day in-hospital death (adjusted HR, 1.41 [95% CI, 1.09-1.81]), while patients with non-dialysis-dependent CKD had an intermediate risk (adjusted HR, 1.25 [95% CI, 1.08-1.44]).

Limitations

Potential residual confounding.

Conclusions

Findings highlight the high mortality of individuals with underlying kidney disease and severe COVID-19, underscoring the importance of identifying safe and effective COVID-19 therapies in this vulnerable population.