Does Fluid Type and Amount Affect Kidney Function in Critical Illness?

Synthetic colloids as priming fluids in cardiopulmonary bypass and postoperative acute kidney injury: a propensity score-matched study

BACKGROUND

The optimal fluid management strategy for patients undergoing on-pump cardiac surgery was controversial regarding the fluid types. This study aimed to compare the impact of hydroxyethyl starch (HES) and succinylated gelatin on postoperative acute kidney injury (AKI).

METHODS

This is a single-center, retrospective study. Adult patients undergoing cardiac surgery with cardiopulmonary bypass (CPB) between 2018 and 2022 were included. Patients were grouped by the priming solution used: HES (the HES group) or succinylated gelatin (the gelatin group). The primary outcome was the incidence of postoperative AKI, and secondary outcomes included continuous renal replacement therapy (CRRT), blood transfusions, myocardial infarction, lung infection, cerebrovascular events, chest drainage, duration of mechanical ventilation, intensive care unit (ICU) stay, in-hospital mortality, and associated costs. Propensity score matching (PSM) was conducted to adjust for characteristic differences between the two groups.

RESULTS

A total of 14,443 patients were included. After 1:1 propensity score matching, 1880 pairs were analyzed. Baseline characteristics were comparable between the matched groups. The incidence of AKI was significantly lower in the gelatin group (3.0% vs. 5.1%, P = 0.001). No significant differences were found in transfusion requirements after score-matching. The use of HES was independently associated with increased odds of AKI (adjusted odds ratio [aOR], 1.785; 95% CI, 1.262-2.526; P = 0.001). The effects of HES use on the occurrence of postoperative AKI were greater in elderly and female patients.

CONCLUSION

The use of HES as a priming solution in on-pump cardiac surgery was associated with an increased risk of postoperative AKI compared to gelatin, although it did not affect transfusion requirements. These findings highlight the importance of considering the priming solution type in fluid management during cardiac surgery.

Changes in corrected carotid flow time induced by recruitment maneuver predict fluid responsiveness in patients undergoing general anesthesia

Non-invasive methods to assess patients' fluid responsiveness during lung-protective ventilation are needed. We hypothesized changes in the corrected carotid flow time induced by the recruitment maneuver predict fluid responsiveness under general anesthesia. Thirty patients undergoing general anesthesia in the supine position were prospectively enrolled. The study protocol was conducted when the patient was hemodynamically stable during surgery. Flow time was measured on Doppler images of the common carotid artery. Carotid flow time, heart rate, stroke volume, stroke volume variation, and pulse pressure variation were recorded before and after a recruitment maneuver at a continuous airway pressure of 30 cmH₂O for 30 s, and before and after volume expansion with 250 mL for 10 min. Patients were defined as fluid responders if the increase in stroke volume was > 10% after volume expansion. Twenty patients (67%) were fluid responders. All Doppler images for carotid flow time were obtained within 30 s. Changes in the corrected flow time accurately predicted fluid responsiveness (area under the curve: 0.82, 95% confidence interval [CI] 0.64-0.94, p = 0.002). The optimal threshold for changes in the corrected flow time was - 11.7% with a sensitivity of 95.0% (95% CI 75.1-99.9%) and a specificity of 80.0% (95% CI 44.4-97.5%). The gray-zone of changes in the corrected flow time was from - 25.1 to - 12.2% and included 12 patients (40%). Changes in the corrected carotid flow time were a useful, technically easy-to-perform, and non-invasive method to predict fluid responsiveness without a need for hemodynamic monitoring or arterial cannulation.

Monitoring peripheral perfusion in sepsis associated acute kidney injury: Analysis of mortality

Microcirculatory disorders have been consistently linked to the pathophysiology of sepsis. One of the major organs affected is the kidneys, resulting in sepsis-associated acute kidney injury (SA-AKI) that correlates considerably with mortality. However, the potential role of clinical assessment of peripheral perfusion as a possible tool for SA-AKI management has not been established. To address this gap, the purpose of this study was to investigate the prevalence of peripheral hypoperfusion in SA-AKI, its association with mortality, and fluid balance. This observational cohort study enrolled consecutive septic patients in the Intensive Care Unit. After fluid resuscitation, peripheral perfusion was evaluated using the capillary filling time (CRT) and peripheral perfusion index (PI) techniques. The AKI was defined based on both serum creatinine and urine output criteria. One hundred and forty-one patients were included, 28 (19%) in the non-SA-AKI group, and 113 (81%) in the SA-AKI group. The study revealed higher peripheral hypoperfusion rates in the SA-AKI group using the CRT (OR 3.6; 95% CI 1.35-9.55; p < 0.05). However, this result lost significance after multivariate adjustment. Perfusion abnormalities in the SA-AKI group diagnosed by both CRT (RR 1.96; 95% CI 1.25-3.08) and PI (RR 1.98; 95% CI 1.37-2.86) methods were associated to higher rates of 28-day mortality (p < 0.01). The PI's temporal analysis showed a high predictive value for death over the first 72 h (p < 0.01). A weak correlation between PI values and the fluid balance was found over the first 24 h (r = - 0.20; p < 0.05). In conclusion, peripheral perfusion was not different intrinsically between patients with or without SA-AKI. The presence of peripheral hypoperfusion in the SA-AKI group has appeared to be a prognostic marker for mortality. This evaluation maintained its predictive value over the first 72 hours. The fluid balance possibly negatively influences peripheral perfusion in the SA-AKI.

Sepsis associated acute kidney injury

Sepsis is defined as organ dysfunction resulting from the host's deleterious response to infection. One of the most common organs affected is the kidneys, resulting in sepsis associated acute kidney injury (SA-AKI) that contributes to the morbidity and mortality of sepsis. A growing body of knowledge has illuminated the clinical risk factors, pathobiology, response to treatment, and elements of renal recovery that have advanced our ability to prevent, detect, and treat SA-AKI. Despite these advances, SA-AKI remains an important concern and clinical burden, and further study is needed to reduce the acute and chronic consequences. This review summarizes the relevant evidence, with a focus on the risk factors, early recognition and diagnosis, treatment, and long term consequences of SA-AKI. In addition to literature pertaining to SA-AKI specifically, pertinent sepsis and acute kidney injury literature relevant to SA-AKI was included.