Fundamentals of Arterial Blood Gas Interpretation.

Acid-base disturbances in patients with cardiopulmonary or other disorders are common and are often misinterpreted or interpreted incompletely. Treating acid-base disorders in greater detail facilitates pathophysiologic understanding and improved therapeutic planning. Understanding the ratiometric relationship between the lungs, which excrete volatile acid as carbon dioxide, and the kidneys, which contribute to maintenance of plasma bicarbonate, allows precise identification of the dominant acid-base disturbance when more than a simple disorder is present and aids in executing a measured treatment response. Concordantly, mapping paired values of the partial pressure of carbon dioxide (PCO2) and the bicarbonate concentration ([HCO3 -]) on a Cartesian coordinate system visually defines an acid-base disorder and validates the ratiometric methodology. We review and demonstrate the algebraic and logarithmic methods of arterial blood gas analysis through the example of a complex acid-base disorder, emphasizing examination of the PCO2-to-[HCO3 -] ratio.

High SARS-CoV-2 Viral Load in Urine Sediment Correlates with Acute Kidney Injury and Poor COVID-19 Outcome.

BACKGROUND: AKI is a complication of coronavirus disease 2019 (COVID-19) that is associated with high mortality. Despite documented kidney tropism of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), there are no consistent reports of viral detection in urine or correlation with AKI or COVID-19 severity. Here, we hypothesize that quantification of the viral load of SARS-CoV-2 in urine sediment from patients with COVID-19 correlates with occurrence of AKI and mortality. METHODS: The viral load of SARS-CoV-2 in urine sediments (U-viral load) was quantified by qRT-PCR in 52 patients with PCR-confirmed COVID-19 diagnosis, who were hospitalized between March 15 and June 8, 2020. Immunolabeling of SARS-CoV-2 proteins Spike and Nucleocapsid was performed in two COVID-19 kidney biopsy specimens and urine sediments. Viral infectivity assays were performed from 32 urine sediments. RESULTS: A total of 20 patients with COVID-19 (39%) had detectable SARS-CoV-2 U-viral load, of which 17 (85%) developed AKI with an average U-viral load four-times higher than patients with COVID-19 who did not have AKI. U-viral load was highest (7.7-fold) within 2 weeks after AKI diagnosis. A higher U-viral load correlated with mortality but not with albuminuria or AKI stage. SARS-CoV-2 proteins partially colocalized with the viral receptor ACE2 in kidney biopsy specimens in tubules and parietal cells, and in urine sediment cells. Infective SARS-CoV-2 was not detected in urine sediments. CONCLUSION: Our results further support SARS-CoV-2 kidney tropism. A higher SARS-CoV-2 viral load in urine sediments from patients with COVID-19 correlated with increased incidence of AKI and mortality. Urinary viral detection could inform the medical care of patients with COVID-19 and kidney injury to improve prognosis.

Effect of Ascorbic Acid, Corticosteroids, and Thiamine on Organ Injury in Septic Shock: The ACTS Randomized Clinical Trial.

IMPORTANCE: The combination of ascorbic acid, corticosteroids, and thiamine has been identified as a potential therapy for septic shock. OBJECTIVE: To determine whether the combination of ascorbic acid, corticosteroids, and thiamine attenuates organ injury in patients with septic shock. DESIGN, SETTING, AND PARTICIPANTS: Randomized, blinded, multicenter clinical trial of ascorbic acid, corticosteroids, and thiamine vs placebo for adult patients with septic shock. Two hundred five patients were enrolled between February 9, 2018, and October 27, 2019, at 14 centers in the United States. Follow-up continued until November 26, 2019. INTERVENTIONS: Patients were randomly assigned to receive parenteral ascorbic acid (1500 mg), hydrocortisone (50 mg), and thiamine (100 mg) every 6 hours for 4 days (n = 103) or placebo in matching volumes at the same time points (n = 102). MAIN OUTCOMES AND MEASURES: The primary outcome was change in the Sequential Organ Failure Assessment (SOFA) score (range, 0-24; 0 = best) between enrollment and 72 hours. Key secondary outcomes included kidney failure and 30-day mortality. Patients who received at least 1 dose of study drug were included in analyses. RESULTS: Among 205 randomized patients (mean age, 68 [SD, 15] years; 90 [44%] women), 200 (98%) received at least 1 dose of study drug, completed the trial, and were included in the analyses (101 with intervention and 99 with placebo group). Overall, there was no statistically significant interaction between time and treatment group with regard to SOFA score over the 72 hours after enrollment (mean SOFA score change from 9.1 to 4.4 [-4.7] points with intervention vs 9.2 to 5.1 [-4.1] points with placebo; adjusted mean difference, -0.8; 95% CI, -1.7 to 0.2; P = .12 for interaction). There was no statistically significant difference in the incidence of kidney failure (31.7% with intervention vs 27.3% with placebo; adjusted risk difference, 0.03; 95% CI, -0.1 to 0.2; P = .58) or in 30-day mortality (34.7% vs 29.3%, respectively; hazard ratio, 1.3; 95% CI, 0.8-2.2; P = .26). The most common serious adverse events were hyperglycemia (12 patients with intervention and 7 patients with placebo), hypernatremia (11 and 7 patients, respectively), and new hospital-acquired infection (13 and 12 patients, respectively). CONCLUSIONS AND RELEVANCE: In patients with septic shock, the combination of ascorbic acid, corticosteroids, and thiamine, compared with placebo, did not result in a statistically significant reduction in SOFA score during the first 72 hours after enrollment. These data do not support routine use of this combination therapy for patients with septic shock. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03389555.

Sodium-Based Osmotherapy in Continuous Renal Replacement Therapy: a Mathematical Approach.

Cerebral edema, in a variety of circumstances, may be accompanied by states of hyponatremia. The threat of brain injury from hypotonic stress-induced astrocyte demyelination is more common when vulnerable patients with hyponatremia who have end stage liver disease, traumatic brain injury, heart failure, or other conditions undergo overly rapid correction of hyponatremia. These scenarios, in the context of declining urinary output from CKD and/or AKI, may require controlled elevations of plasma tonicity vis-à-vis increases of the plasma sodium concentration. We offer a strategic solution to this problem via sodium-based osmotherapy applied through a conventional continuous RRT modality: predilution continuous venovenous hemofiltration.

Emerging Threat: Changing Epidemiology of Hepatitis A and Acute Kidney Injury.

In the past decade, hepatitis A has been considered a rare disease in the United States, largely due to targeted vaccination of at-risk children. Evolving epidemiology has resulted in decreasing immunity and increasing hepatitis A infections among adults who are more likely to experience severe disease. A surge in outbreaks has been noted in the past 2 years, resulting in a high volume of hepatitis A related hospitalizations and complications in otherwise healthy individuals. The traditional understanding that acute kidney injury is a rare extrahepatic manifestation is being challenged by the resurgence of hepatitis A in a more vulnerable population. This review examines the epidemiologic factors that contributed to current public health concern and the association between hepatitis A and acute kidney injury.

Emergent airway management in a patient with in situ tracheal stent: A lesson learned.

The prevalence of in situ tracheal stents has increased in the past two decades for the management of malignant and benign central airway diseases for either palliation or definitive therapy. Recent placement of a tracheal stent has been associated with edema of the upper airway; therefore, these patients are at a great risk for airway collapse, especially within the days most recent to the procedure. The authors present the case of a morbidly obese patient with a tracheal stent admitted to the Intensive Care Unit who developed acute respiratory failure and was found to be "unable to ventilate, unable to intubate." Surgical airway approach through a cricothyroidotomy failed to provide a patent airway and the patient subsequently developed cardiac arrest and expired. The presence of tracheal stent poses a high challenge during emergent airway interventions; thus, carefully planned airway manipulation in such patients is paramount in order to avoid catastrophic outcomes.

Epidemiology of Cardiorenal Syndrome.

Cardiorenal syndrome is a spectrum of disorders that emphasizes the bidirectional nature of cardiac and kidney injury. Observational and retrospective studies have helped us to understand the prevalence and burden of each of the 5 types of cardiorenal syndromes. Cardiorenal syndrome type 1 is the most common. The nature of epidemiologic data limits clear delineation between cardiorenal syndrome types 2 and 4. Overall, the presence of cardiac or renal dysfunction strongly predicts a poor outcome of the contrary organ.

Pseudo-Renal Tubular Acidosis: Conditions Mimicking Renal Tubular Acidosis.

Hyperchloremic metabolic acidosis, particularly renal tubular acidosis, can pose diagnostic challenges. The laboratory phenotype of a low total carbon dioxide content, normal anion gap, and hyperchloremia may be misconstrued as hypobicarbonatemia from renal tubular acidosis. Several disorders can mimic renal tubular acidosis, and these must be appropriately diagnosed to prevent inadvertent and inappropriate application of alkali therapy. Key physiologic principles and limitations in the assessment of renal acid handling that can pose diagnostic challenges are enumerated.

Change in Lactate Levels After Hemodialysis in Patients With End-Stage Renal Disease.

STUDY OBJECTIVE: Patients with end-stage renal disease commonly visit the emergency department (ED). The purpose of this investigation is to examine the prevalence of baseline abnormal lactate levels and to evaluate the effects of hemodialysis on serum lactate levels. METHODS: This was a prospective observational cohort study performed at an outpatient dialysis facility at an urban tertiary care hospital. The study consisted of 226 patients with end-stage renal disease who were receiving long-term hemodialysis and were enrolled during a 2-day period at the beginning of December 2015. Blood drawn for lactate levels was immediately analyzed before and after hemodialysis sessions. All patients completed their hemodialysis sessions. RESULTS: The prevalence of an abnormal lactate level (greater than 1.8 mmol/L) before hemodialysis was 17.7% (n=40). Overall, lactate levels decreased by 27% (SD 35%) after hemodialysis, with a decrease of 37% (SD 31%) for subgroups with a lactate level of 1.9 to 2.4 mmol/L, and 62% (SD 14%) with a lactate of 2.5 to 3.9 mmol/L. CONCLUSION: The data presented help providers understand the prevalence of abnormal lactate values in an outpatient end-stage renal disease population. After hemodialysis, lactate levels decreased significantly. This information may help medical providers interpret lactate values when patients with end-stage renal disease present to the ED.