Oliguria in Critically Ill Patients: Impact on AKI Classification and Outcomes Prediction
Context & Objectives : Current definition and staging of acute kidney injury (AKI) considers both serum creatinine (sCr) and urinary output (UO) alterations. However, the relevance of oliguria-based criteria is disputed. We aimed to determine the contribution of oliguria, as defined by KDIGO criteria, to AKI diagnosis, severity assessment and mortality prediction.
Material and methods : We conducted a cohort study including all adult patients consecutively admitted within a multi-disciplinary intensive care unit between January 1st 2010 and June 15th 2020. Daily sCr and hourly UO measurements along with socio-demographic characteristics and severity scores were extracted from our electronic medical charts. Long-term mortality was assessed by cross-referencing our database with the Swiss national death registry. We determined the onset and severity of AKI according to KDIGO classification using UO and sCr criteria separately and assessed their agreement. Using a multivariable model accounting for baseline characteristics, severity scores and sCr stages, we evaluated the relative influence of UO criteria on 90-day mortality. Sensitivity analyses were conducted to assess the impact of missing sCr, body weight and UO values.
Results: Among the 15'620 patients included in the study [10’330 (66.1%) males, median age 65.0 years (IQR, 53.0 - 75.0), median SAPS score 40.0 (IQR, 30.0 - 53.0), median follow-up 67.0 months (IQR, 34.0 - 100.0)], 12’143 (77.7%) fulfilled AKI criteria. SCr and UO criteria had poor agreement on AKI diagnosis and staging (Cohen’s weighted kappa = 0.36, 95% CI 0.34 - 0.37, p < 0.001). Compared to the isolated use of sCr criteria, consideration of UO criteria enabled to identify AKI in 5'630 (36.0%) patients. Those patients had a higher 90-day mortality than no-AKI patients (respectively 12.9% and 8.3%, p < 0.001). On multivariable analysis accounting for sCr stage, comorbidities and illness severity, UO stage 2 and 3 were associated with a higher 90-day mortality [OR 2.4 (1.6 - 3.8), p < 0.001, and 6.2 (3.7 - 10.5), p < 0.001, respectively]. These results remained significant in all sensitivity analyses.
Conclusions: Oliguria lasting more than 12 hours (KDIGO stage 2 or 3) has major diagnostic and prognostic implications, irrespective of sCr elevations.
COVID-19: Impact on Circuit Lifetime and Performance during Continuous Renal Replacement Therapy
Introduction: SARS-CoV-2 infection is associated with a coagulopathy characterized by increased fibrinogen and D-dimers levels. The impact of this coagulopathy on continuous renal replacement therapy (CRRT) circuit lifespan and performance remains unknown.
Methods: In this prospective observational study, we enrolled all consecutive patients who received CRRT in the intensive care unit of a tertiary hospital between September and December 2020. All therapies were administered in continuous veno-venous hemodialysis mode with regional citrate anticoagulation. We collected patients’ baseline characteristics, laboratory results, CRRT circuit lifespan as well as plasma and effluent samples at 12 (T1), 24 (T2), 48 (T3) and 72 hours (T4) of CRRT circuit initiation. At each study time point, we computed urea, creatinine and β2-microglobulin clearance. Results obtained in patients with COVID-19 (C19 group) were compared to those without COVID-19 (control group). Circuits’ lifespan was assessed using Kaplan-Meier estimates and compared using log-rank test. Filter clearances at each study time point were compared using Student’s T-test. Mixed models analyses were conducted to assess determinants of circuit lifetime and filter clearance.
Results: We included 35 patients, 26 (74%) males with a median age of 68 [IQR 57– 71] years. Of those 16 (45%) were COVID-19 positive. We analyzed 150 CRRT circuits: 77 (51.3%) in the C19 group and 73 (48.7%) in the control group. Compared to patients in the control group, those in the C19 group had a significantly shorter median circuit lifespan (57 [49.0 – 66.0] versus 68 [66 – 71] hours, p = 0.016). They had a lower median urea (T1 27.5 vs 31.4; T2 26.8 vs 32.6; T3 27.3 vs 30.4 and T4 26.4 vs 30.7 ml/kg/h, all p < 0.05) and creatinine (T1 22.7 vs 24.7; T2 23.0 vs 24.5; T3 20.4 vs 22.9 and T4 21.3 vs 22.8 ml/kg/h, respective p values: 0.03, 0.02, 0.06 and 0.08) clearance at all study time points. However, there was no difference in β2-microglobulin’s clearance between the two groups (respective p values: 0.6, 1.0, 0.8 and 0.7).
Conclusion: Patients with COVID-19 disease had a shorter CRRT circuit lifetime and a lower urea and creatinine clearance. The magnitude of this difference was, however, limited and further studies are required to explore clinical implications of such differences.
Prospective observational study on Health Care Worker Exposure to Sevoflurane and Isoflurane during postoperative Sedation with the Anaesthetic Conserving Device (AnaConDa®) - a safe option during intravenous sedative shortage in COVID-19 pandemic
Background: Volatile anaesthetic agents have been used in the intensive care unit (ICU) setting as sedative due to favorable pharmacokinetics. Worldwide shortage of invtravenous sedatives during the actual COVID-19 pandemic has emphasised volatiles as a valuable alternative for ICU sedation. Nevertheless, the use of volatile sedation has been limited by difficulties on safety concerns over environmental pollution and staff exposure in an ICU. The aim of the study was to evaluate occupational exposure levels to sevoflurane and isoflurane during the use of Anaesthetic Conserving Device (AnaConDa®).
Methods: A prospective observational study on occupational exposure was conducted in a cardiovascular ICU at the University Hospital of Zurich 2008, 2011 and 2016 on post-conditioning in cardiac patients. Concentrations of either sevoflurane or isoflurane were measured in indoor air at the sites of volatile sedation using photoacoustic spectroscopy during volatile sedation with sevoflurane and isoflurane applied by AnaConDa®. Measured gas concentrations were extrapolated and interpreted in accordance with current legal guidelines and allowed workplace concentrations. In addition, the nursing work cycle at bedside was logged in a standardized manner in order to correlate specific staff activities with measured anaesthetic gas concentrations.
Results: Sevoflurane and isoflurane concentrations were measured in three series over a cumulative operating time of the AnaConDa® system of more than 400 hours at eight patients. Concentrations mean values for an eight-hour shift for health care stuff never exceeded the bedside air concentration of 1 part per million [ppm] and the exposition of the health care stuff was less than 10% of the workplace limit values for sevoflurane (10 ppm) and isoflurane (10 ppm). The maximum measured concentration during regular tasks was 18.2 ppm during exchange of the AnaconDa® filter. Higher concentrations only could be measured close to the waste gas absorber CONTRAfluran® the exhaust of the oxygenator and the patient gas monitor. No one of the measured peaks had an impact on the mean eight-hour workplace exposure or exceeds the time limited short-term exposure limit neither for sevoflurane nor isoflurane.
Conclusion: Volatile sedation via AnaConDa® appears to be justifiable in terms of the contamination indoor air on the ICU if the device is handled correctly. Occupational exposure can be reduced by gas extraction systems or scavenging
SGI/SSMI Young Investigator Research Grant 2021 – PENGUIN-Trial