Immediate hemodynamic response to furosemide in patients undergoing chronic hemodialysis

The acute effects of furosemide in acute heart failure assessed by remote dielectric sensing. A protocol

INTRODUCTION

Intravenous loop diuretics have been a key component in treating pulmonary oedema since the 1960s and have a Class 1 recommendation in the 2021 guidelines for acute heart failure (AHF). While the diuretic effect of loop diuretics is well established, it remains unclear how furosemide influences pulmonary congestion and cardiac filling pressures in the hyperacute phase before significant diuresis occurs.

METHODS

This was a prospective study of adult patients with AHF and objective signs of pulmonary congestion admitted to the cardiac ward. Remote dielectric sensing (ReDS) will directly measure lung fluid content, and cardiac filling pressures will be assessed by echocardiography with Doppler and strain analysis.

CONCLUSIONS

This study will examine if furosemide leads to a hyperacute reduction in pulmonary congestion assessed by ReDS independent of diuretic effects in patients with AHF. We hypothesise that the haemodynamic effect of furosemide shown on pulmonary congestion may explain the subjective instant relief in patients with AHF receiving furosemide.

FUNDING

Dr. Grand's salary during this project is supported by a research grant from the Danish Cardiovascular Academy funded by Novo Nordisk Foundation grant number NNF20SA0067242 and by the Danish Heart Foundation.

TRIAL REGISTRATION

This protocol was approved by the Scientific Ethical Committee, H-23029822, and the Danish Data Protection Agency P-2013-14703. The protocol was registered with ClinicalTrial.org on 29 August 2023 (Identifier: NCT06024889).

Case Studies in Physiology: Untangling the cause of hypoxemia in a patient with obesity with acute leukemia

Diagnosing the cause of hypoxemia and dyspnea can be complicated in complex patients with multiple comorbidities. This "Case Study in Physiology" describes an man with obesity admitted to the hospital for relapse of acute lymphoblastic leukemia, who experienced progressive hypoxemia, shortness of breath, and dyspnea on exertion during his hospitalization. After initial empirical treatment with diuresis and antibiotics failed to improve his symptoms and because an arterial blood gas measurement was not readily available, we applied a novel, recently described physiological method to estimate the arterial partial pressure of oxygen from the peripheral saturation measurement and calculate the alveolar-arterial oxygen difference to discern the source of his hypoxemia and dyspnea. Using basic physiological principles, we describe how hypoventilation, anemia, and the use of a β blocker and furosemide, collaborated to create a "perfect storm" in this patient that impaired oxygen delivery and limited utilization. This case illustrates the application of innovative physiology methodology in medicine and provides a strong rationale for continuing to integrate physiology education in medical education.NEW & NOTEWORTHY Discerning the cause of dyspnea and hypoxemia in complex patients can be difficult. We describe the "real world" application of an innovative methodology to untangle the underlying physiology in a patient with multiple comorbidities. This case further demonstrates the importance of applying physiology to interrogate the underlying cause of a patient's symptoms when treatment based on probability fails.

Cytokine-Ion Channel Interactions in Pulmonary Inflammation

The lungs conceptually represent a sponge that is interposed in series in the bodies’ systemic circulation to take up oxygen and eliminate carbon dioxide. As such, it matches the huge surface areas of the alveolar epithelium to the pulmonary blood capillaries. The lung’s constant exposure to the exterior necessitates a competent immune system, as evidenced by the association of clinical immunodeficiencies with pulmonary infections. From the in utero to the postnatal and adult situation, there is an inherent vital need to manage alveolar fluid reabsorption, be it postnatally, or in case of hydrostatic or permeability edema. Whereas a wealth of literature exists on the physiological basis of fluid and solute reabsorption by ion channels and water pores, only sparse knowledge is available so far on pathological situations, such as in microbial infection, acute lung injury or acute respiratory distress syndrome, and in the pulmonary reimplantation response in transplanted lungs. The aim of this review is to discuss alveolar liquid clearance in a selection of lung injury models, thereby especially focusing on cytokines and mediators that modulate ion channels. Inflammation is characterized by complex and probably time-dependent co-signaling, interactions between the involved cell types, as well as by cell demise and barrier dysfunction, which may not uniquely determine a clinical picture. This review, therefore, aims to give integrative thoughts and wants to foster the unraveling of unmet needs in future research.

The influence of fluid and diuretic administration on the index of atrial contribution in sequentially paced patients

AIMS

To examine whether acute changes in patient hydration can change atrial contribution (AC) to circulatory function.

METHODS AND RESULTS

Atrial contribution was quantified by beat-to-beat changes in the amplitude of pulse oximetry signal in 24 paced outpatients. Changes in body weight were used for assessment of changes in total body water. The first measurement was performed at steady state. The second measurement was made after infusion of saline (5 mL/kg) and the third measurement was obtained 2 h after a bolus of furosemide (1 mg/kg). Changes found after furosemide administration (compared with steady state): a substantial decrease in body weight from median 78.6 (interquartile range 65.7-86.5) to 77.1 (64.4-85.6) kg (P < 0.001), accompanied by an increase in AC from 30.4 (20.2-47.1) up to 43.3 (30.6-80.9)% (P < 0.001). An increase in heart rate and shortening of the atrioventricular conduction time occurred during acute hypohydration in some of the subjects.

CONCLUSION

Administration of furosemide was followed by a decrease in body weight and an increase in AC to stroke volume. This suggests that in conditions where pre-load is reduced cardiac output is preserved by an increase in AC enforced by sympathetic activation.

Modern Management of Cardiogenic Pulmonary Edema

Cardiogenic pulmonary edema (CPE) is a life-threatening condition that is frequently encountered in standard emergency medicine practice. Traditionally, diagnosis was based on physical assessment and chest radiography and treatment focused on the use of morphine sulfate and diuretics. Numerous advances in diagnosis and treatment have been made, however. Serum testing for B-type natriuretic peptide (BNP) has improved the accuracy of diagnoses in these patients. Treatment should focus on fluid redistribution with aggressive preload and afterload reduction rather than simply on diuresis. Some specific medications and noninvasive positive pressure ventilation have been shown to be safe and rapidly effective in improving patients' symptoms and improve outcomes.

Review Articles: Nondialytic Management of Hyperkalemia and Pulmonary Edema Among End-Stage Renal Disease Patients: An Evaluation of the Evidence

Congestive heart failure (CHF) and hyperkalemia are the two leading reasons for emergency dialysis among individuals with end-stage renal disease (ESRD). While hemodialysis provides definitive treatment of both hyperkalemia and volume overload among ESRD patients, for those who present outside of "regular dialysis hours," institution of dialysis may be delayed. Nondialytic management can be instituted immediately and should be the initial therapy in the management of hyperkalemia and CHF in these individuals. Current available evidence does not allow conclusions as to whether treatment with nondialytic strategies alone results in different outcomes than nondialytic strategies coupled with emergent hemodialysis. Therefore, whether or not nondialytic management alone is appropriate remains a matter of individual judgment that should be decided on a case-by-case basis.

Evaluation and management of acutely decompensated chronic heart failure in the emergency department

A wide range of patients with symptomatic heart failure seek treatment in the emergency department. While there is no single approach to the diversity of patients with acutely decompensated heart failure, certain overarching principles apply. For patients with acute pulmonary edema or cardiogenic shock, the first priority must be rapid stabilization and treatment of reversible problems. For patients with less dramatic presentations, a more systematic search for precipitating factors may be required. Therapy, in general, is directed at reversing dyspnea and/or hypoxemia caused by pulmonary edema, improving systemic perfusion, and reducing myocardial oxygen demand. While morphine and diuretics still have their traditional roles, vasodilators and inotropic agents play an increasingly important part in the modern pharmacologic approach to decompensated heart failure in the emergency department. After evaluation and stabilization in the emergency department, most patients will require hospital admission, although a subset of low-risk patients may be appropriate for discharge to home following a period of observation. Strategies to optimize emergency department care are likely to have an impact upon patient outcomes and upon resource utilization. (c)2001 by CHF, Inc.

Arterial and venous compliance in obese and nonobese subjects

Arterial compliance and central blood volume were evaluated in obese and nonobese patients with and without hypertension. Arterial compliance was lower in the hypertensive group, although obese subjects, regardless of their blood pressure, had higher arterial compliance. The ratio of central blood volume to total blood volume was highest in hypertensive patients, whether obese or lean, indicating increased venoconstriction.

Emergencies in continuous dialysis patients: diagnosis and management

The number of patients undergoing long-term hemodialysis and peritoneal dialysis is growing in the United States. To provide adequate emergent care to these patients emergency physicians must understand the alterations in normal physiologies present in these patients and how this may affect care. Cardiovascular disease and infection (especially Staphylococcus aureus sepsis) are the leading causes of death among dialysis patients. These patients are also subject to a significantly higher incidence of life-threatening electrolyte disturbances, particularly hyperkalemia and hypercalcemia, than the general population. Suicide, cardiac tamponade, intracranial hemorrhage, bleeding disorders, and bowel infarction are also much more frequent. The inability of dialysis patients to excrete drugs, metabolites, toxins, and fluids significantly alters their responses to common emergencies and should directly influence their care. Failure to recognize these differences in physiology may result in the use of standard forms of emergency therapy that may compound, rather than treat, the underlying disorder. Although most dialysis patients who come into an emergency department have conditions that can, and should, be managed by their nephrologist, the presence of a life threatening emergency requires prompt, appropriate therapy by the emergency physician.

Pulmonary edema in the renal failure patient

A patient with chronic renal failure presenting to the emergency department with acute pulmonary edema has a true life-threatening emergency. Whereas conventional treatment modalities may prove useful, more unusual therapeutic measures may be necessary. A case is presented followed by useful recommendations for the emergency physician faced with such a patient.