Furosemide exacerbated the impairment of renal function, oxygenation and medullary damage in a rat model of renal ischemia/reperfusion induced AKI.

BACKGROUND: Perioperative acute kidney injury (AKI) caused by ischemia-reperfusion (IR) is a significant contributor to mortality and morbidity after major surgery. Furosemide is commonly used in postoperative patients to promote diuresis and reduce tissue edema. However, the effects of furosemide on renal microcirculation, oxygenation and function are poorly understood during perioperative period following ischemic insult. Herein, we investigated the effects of furosemide in rats subjected IR insult. METHODS: 24 Wistar albino rats were divided into 4 groups, with 6 in each; Sham-operated Control (C), Control + Furosemide (C + F), ischemia/reperfusion (IR), and IR + F. After induction of anesthesia (BL), supra-aortic occlusion was applied to IR and IR + F groups for 45 min followed by ongoing reperfusion for 15 min (T1) and 2 h (T2). Furosemide infusion was initiated simultaneously in the intervention groups after ischemia. Renal blood flow (RBF), vascular resistance (RVR), oxygen delivery (DO2ren) and consumption (VO2ren), sodium reabsorption (TNa+), oxygen utilization efficiency (VO2/TNa+), cortical (CµO2) and medullary (MµO2) microvascular oxygen pressures, urine output (UO) and creatinine clearance (Ccr) were measured. Biomarkers of inflammation, oxidative and nitrosative stress were measured and kidneys were harvested for histological analysis. RESULTS: IR significantly decreased RBF, mainly by increasing RVR, which was exacerbated in the IR + F group at T2 (2198 ± 879 vs 4233 ± 2636 dyne/s/cm5, p = 0.07). CµO2 (61.6 ± 6.8 vs 86 ± 6.6 mmHg) and MµO2 (51.1 ± 4.1 vs 68.7 ± 4.9 mmHg, p < 0.05) were both reduced after IR and did not improve by furosemide. Moreover, VO2/TNa+ increased in the IR + F group at T2 with respect to the IR group (IR: 3.3 ± 2 vs IR + F: 8.2 ± 10 p = 0.07) suggesting a possible deterioration of oxygen utilization. Ccr did not change, but plasma creatinine increased significantly in IR + F groups. Histopathology revealed widespread damage both in the cortex and medulla in IR, IR + F and C + F groups. CONCLUSION: Renal microvascular oxygenation, renal function, renal vascular resistance, oxygen utilization and damage were not improved by furosemide administration after IR insult. Our study suggests that furosemide may cause additional structural and functional impairment to the kidney following ischemic injury and should be used with caution.

Identifying a sublingual triangle as the ideal site for assessment of sublingual microcirculation.

The sublingual mucosa is a commonly used intraoral location for identifying microcirculatory alterations using handheld vital microscopes (HVMs). The anatomic description of the sublingual cave and its related training have not been adequately introduced. The aim of this study was to introduce anatomy guided sublingual microcirculatory assessment. Measurements were acquired from the floor of the mouth using incident dark-field (IDF) imaging before (T0) and after (T1) sublingual cave anatomy instructed training. Instructions consists of examining a specific region of interested identified through observable anatomical structures adjacent and bilaterally to the lingual frenulum which is next to the sublingual papilla. The anatomical location called the sublingual triangle, was identified as stationed between the lingual frenulum, the sublingual fold and ventrally to the tongue. Small, large, and total vessel density datasets (SVD, LVD and TVD respectively) obtained by non-instructed and instructed measurements (NIN (T0) and IM (T1) respectively) were compared. Microvascular structures were analyzed, and the presence of salivary duct-related microcirculation was identified. A total of 72 video clips were used for analysis in which TVD, but not LVD and SVD, was higher in IM compared to NIM (NIM vs. IM, 25 ± 2 vs. 27 ± 3 mm/mm2 (p = 0.044), LVD NIM vs. IM: 7 ± 1 vs. 8 ± 1mm/mm2 (p = 0.092), SVD NIM vs. IM: 18 ± 2 vs. 20 ± 3 mm/mm2 (p = 0.103)). IM resulted in microcirculatory assessments which included morphological properties such as capillaries, venules and arterioles, without salivary duct-associated microcirculation. The sublingual triangle identified in this study showed consistent network-based microcirculation, without interference from microcirculation associated with specialized anatomic structures. These findings suggest that the sublingual triangle, an anatomy guided location, yielded sublingual based measurements that conforms with international guidelines. IM showed higher TVD values, and future studies are needed with larger sample sizes to prove differences in microcirculatory parameters.

Effect of prone positioning on end-expiratory lung volume, strain and oxygenation change over time in COVID-19 acute respiratory distress syndrome: A prospective physiological study.

Background: Prone position (PP) is a recommended intervention in severe classical acute respiratory distress syndrome (ARDS). Changes in lung resting volume, respiratory mechanics and gas exchange during a 16-h cycle of PP in COVID-19 ARDS has not been yet elucidated. Methods: Patients with severe COVID-19 ARDS were enrolled between May and September 2021 in a prospective cohort study in a University Teaching Hospital. Lung resting volume was quantitatively assessed by multiple breath nitrogen wash-in/wash-out technique to measure the end-expiratory lung volume (EELV). Timepoints included the following: Baseline, Supine Position (S1); start of PP (P0), and every 4-h (P4; P8; P12) until the end of PP (P16); and Supine Position (S2). Respiratory mechanics and gas exchange were assessed at each timepoint. Measurements and main results: 40 mechanically ventilated patients were included. EELV/predicted body weight (PBW) increased significantly over time. The highest increase was observed at P4. The highest absolute EELV/PBW values were observed at the end of the PP (P16 vs S1; median 33.5 ml/kg [InterQuartileRange, 28.2-38.7] vs 23.4 ml/kg [18.5-26.4], p < 0.001). Strain decreased immediately after PP and remained stable between P4 and P16. PaO2/FiO2 increased during PP reaching the highest level at P12 (P12 vs S1; 163 [138-217] vs 81 [65-97], p < 0.001). EELV/PBW, strain and PaO2/FiO2 decreased at S2 although EELV/PBW and PaO2/FiO2 were still significantly higher as compared to S1. Both absolute values over time and changes of strain and PaO2/FiO2 at P16 and S2 versus S1 were strongly associated with EELV/PBW levels. Conclusion: In severe COVID-19 ARDS, EELV steadily increased over a 16-h cycle of PP peaking at P16. Strain gradually decreased, and oxygenation improved over time. Changes in strain and oxygenation at the end of PP and back to SP were strongly associated with changes in EELV/PBW. Whether the change in EELV and oxygenation during PP may play a role on outcomes in COVID-ARDS deserves further investigation. Clinical trial registration: [www.ClinicalTrials.gov], identifier [NCT04818164].

Incidence, Risk Factors, and Prognosis of Bloodstream Infections in COVID-19 Patients in Intensive Care: A Single-Center Observational Study.

BACKGROUND: Critically ill COVID-19 patients are prone to bloodstream infections (BSIs). AIM: To evaluate the incidence, risk factors, and prognosis of BSIs developing in COVID-19 patients in the intensive care unit (ICU). METHODS: Patients staying at least 48 h in ICU from 22 March 2020 to 25 May 2021 were included. Demographic, clinical, and laboratory data were analyzed. RESULTS: The median age of the sample (n = 470) was 66 years (IQR 56.0-76.0), and 64% were male. The three most common comorbidities were hypertension (49.8%), diabetes mellitus (32.8%), and coronary artery disease (25.7%). Further, 252 BSI episodes developed in 179 patients, and the BSI incidence rate was 50.2 (95% CI 44.3-56.7) per 1000 patient-days. The source of BSI is central venous catheter in 42.5% and lower respiratory tract in 38.9% of the episodes. Acinetobacter baumannii (40%) and carbapenem-resistant Klebsiella pneumoniae (21%) were the most common pathogens. CRP levels were lower in patients receiving tocilizumab. Multivariable analysis revealed that continuous renal replacement therapy, extracorporeal membrane oxygenation, and treatment with a combination of methylprednisolone and tocilizumab were independent risk factors for BSI. The estimated cumulative risk of developing first BSI episode was 50% after 6 days and 100% after 25 days. Of the 179 patients, 149 (83.2%) died, and a statistically significant difference (p < 0.001) was found in the survival distribution in favor of the group without BSI. CONCLUSION: BSI is a common complication in COVID-19 patients followed in the ICU, and it can lead to mortality. Failure in infection control measures, intensive immunosuppressive treatments, and invasive interventions are among the main factors leading to BSIs.

What About Compressing the Oesophagus with an Ultrasound Probe for a Modified Sellick Maneuver?

OBJECTIVE: Debates continue about the cricoid pressure, which has been used for many years to prevent gastric aspiration during intubation. Using ultrasound, the effects of this maneuver and alternatives like paralaryngeal pressure are revealed. The aim of this observational study was to determine the effect of paralaryngeal pressure with an ultrasound probe on the esophageal diameter in patients with different body mass indexes and neck circumferences. METHODS: After measuring the neck circumference at the level of the cricoid cartilage, the esophagus was visualized by ultrasonography. Compression was applied medially at a 45° angle toward the vertebral column by the ultrasound probe and esophageal anteroposterior outer diameters were measured. Correlations between body mass index, neck circumference, esophageal diameter, and esophageal diameter change ratio were evaluated with Pearson's r value. RESULTS: One hundred ten volunteers (52 women and 58 men) with mean age 33.7 ± 8.02 years and mean body mass index 25.6 ± 4.65 kg m-2 were recruited. The esophagus was located 78.18% partially to the left, 4.54% completely to the left, 1.81% to the right of the cricoid ring. In 15.45%, esophagus could not be displayed. The mean diameter of the esophagus was 7.6 ± 1.1 mm before pressure and 5.6 ± 0.09 mm after pressure (P < .001). There was no significant correlation between diameter change percentage and body mass index (r=-0.22; P > .05). However, weak correlation was found between diameter change percentage and neck circumference (r=-0.33; P=.016). CONCLUSIONS: Paralaryngeal pressure with an ultrasound probe has the potential to occlude the esophagus and may be effective in all patient groups.

Assessment of sublingual microcirculation in critically ill patients: consensus and debate.

The main concern in shock and resuscitation is whether the microcirculation can carry adequate oxygen to the tissues and remove waste. Identification of an intact coherence between macro- and microcirculation during states of shock and resuscitation shows a functioning regulatory mechanism. However, loss of hemodynamic coherence between the macro and microcirculation can be encountered frequently in sepsis, cardiogenic shock, or any hemodynamically compromised patient. This loss of hemodynamic coherence results in an improvement in macrohemodynamic parameters following resuscitation without a parallel improvement in microcirculation resulting in tissue hypoxia and tissue compromise. Hand-held vital microscopes (HVMs) can visualize the microcirculation and help to diagnose the nature of microcirculatory shock. Although treatment with the sole aim of recruiting the microcirculation is as yet not realized, interventions can be tailored to the needs of the patient while monitoring sublingual microcirculation. With the help of the newly introduced software, called MicroTools, we believe sublingual microcirculation monitoring and diagnosis will be an essential point-of-care tool in managing shock patients.

Successful Reduction of Creatine Kinase and Myoglobin Levels in Severe Rhabdomyolysis Using Extracorporeal Blood Purification (CytoSorb®).

Rhabdomyolysis, if severe, can lead to acute kidney injury (AKI). Myoglobin is an iron and oxygen-binding protein that is freely filtered by the glomerulus. Precipitation of myoglobin in the nephrons' distal parts is responsible for tubular damage with AKI as a consequence. Extracorporeal clearance of myoglobin is conventionally attempted by the use of continuous renal replacement therapy (CRRT) with high cut-off dialysis membranes to limit the extent of the damage. We describe a case of a 56-year-old man with traumatic crush injury and a persistent source of muscle ischaemia unresponsive to high dose CRRT with EMiC-2 filter. Due to therapy failure, he was subsequently treated with the addition of a haemoadsorber (CytoSorb®) to the circuit. This reduced myoglobin and creatine kinase levels successfully despite ongoing tissue ischaemia. However, CytoSorb® was not enough to maintain microcirculatory perfusion, resulting in the eventual demise of the patient due to severity of the injury. Our report indicates that myoglobin was efficiently removed with CytoSorb® following exchange with the conventional high cut-off filter in continuous venovenous haemodialysis in severe traumatic rhabdomyolysis.