Half the V by 120: A practical approach to the prevention of the dialysis disequilibrium syndrome.

The dialysis disequilibrium syndrome (DDS) results from osmotic shifts between the blood and the brain compartments. Patients at risk for DDS include those with very elevated blood urea nitrogen, concomitant hypernatremia, metabolic acidosis, and low total body water volumes. By understanding the underlying pathophysiology and applying urea kinetic modeling, it is possible to avoid the occurrence of this disorder. A urea reduction ratio (URR) of no more than 40%-45% over 2 h is recommended for the initial hemodialysis treatment. The relationship between the URR and Kt/V is useful when trying to model the dialysis treatment to a specific URR target. A simplified relationship between Kt/V and URR is provided by the equation: Kt/V = -ln (1 - URR). A URR of 40% is roughly equivalent to a Kt/V of 0.5. The required dialyzer urea clearance to achieve this goal URR in a 120-min treatment can simply be calculated by dividing half the patient's volume of distribution of urea by 120. The blood flow rate and dialyzer mass transfer coefficient (K0 A) required to achieve this clearance can then be plotted on a nomogram. Other methods to reduce the risk of DDS are reviewed, including the use of continuous renal replacement therapy.

An Unusual Case of Pulmonary Cryptococcus.

Cryptococcal infections are caused by encapsulated fungi Cryptococcus gattii and C. neoformans. Inhalation commonly causes innocuous colonization but may cause meningitis or disseminated disease via hematogenous spread. Cryptococcosis occurs most commonly in immunocompromised patients including those with acquired immunodeficiency syndrome, meningoencephalitis or disseminated disease. However, cryptococcosis can occur as asymptomatic isolated pulmonary nodules in immunocompetent patients. Here we present a unique retrospective case report of a 55-year-old immunocompetent man who presented with pleuritic chest pain, productive cough, dyspnea on exertion, chills, night sweats, and weight loss. A computed tomography scan of his chest revealed multiple ground-glass opacities throughout both lung fields. The results of his autoimmune evaluation and human immunodeficiency virus tests were negative. A biopsy obtained through video-assisted thoracoscopic surgery revealed mucicarmine staining capsules confirming Cryptococcus, requiring treatment with amphotericin, flucytosine, and fluconazole. This case highlights the rarely studied presentation of symptomatic diffuse pulmonary cryptococcal infection in an immunocompetent patient requiring treatment.