Fallacies of High‐Speed Hemodialysis

Abstract

Chronic hemodialysis sessions, as developed in Seattle in the 1960s, were long procedures with minimal intra- and interdialytic symptoms. Financial and logistical pressures related to the overwhelming number of patients requiring hemodialysis created an incentive to shorten dialysis time to four, three, and even two hours per session in a thrice weekly schedule. This method spread rapidly, particularly in the United States, after the National Cooperative Dialysis Study suggested that time of dialysis is of minor importance as long as urea clearance multiplied by dialysis time and scaled to total body water (Kt/V(urea)) equals 0.95-1.0. This number was later increased to 1.3, but the assumption remained unchanged that hemodialysis time is of minimal importance as long as it is compensated by increased urea clearance. Patients accepted short dialysis as a godsend, believing that it would not be detrimental to their well-being and longevity. However, Kt/V(urea) measures only removal of low molecular weight substances and does not consider removal of larger molecules. Besides, it does not correlate with the other important function of hemodialysis, namely ultrafiltration. Whereas patients with substantial residual renal function may tolerate short dialysis sessions, the patients with little or no urine output tolerate short dialyses poorly because the ultrafiltration rate at the same interdialytic weight gain is inversely proportional to dialysis time. Rapid ultrafiltration is associated with cramps, nausea, vomiting, headache, fatigue, hypotensive episodes during dialysis, and hangover after dialysis; patients remain fluid overloaded with subsequent poor blood pressure control, left ventricular hypertrophy, diastolic dysfunction, and high cardiovascular mortality. Short, high-efficiency dialysis requires high blood flow, which increases demands on blood access. The classic wrist arteriovenous fistula, the access with the best longevity and lowest complication rates, provides "insufficient" blood flow and is replaced with an arteriovenous graft fistula or an intravenous catheter. Moreover, to achieve high blood flows, large diameter intravenous catheters are used; these fit veins "too tightly," so predispose the patient to central-vein thrombosis. Longer hemodialysis sessions (5-8 hrs, thrice weekly), as practiced in some centers, are associated with lower complication rates and better outcomes. Frequent dialyses (four or more sessions per week) provide better clinical results, but are associated with increased cost. It is my strong belief that a wide acceptance of longer, gentler dialysis sessions, even in a thrice weekly schedule, would improve overall hemodialysis results and decrease access complications, hospitalizations, and mortality, particularly in anuric patients.

Satellite dialysis nursing: technology, caring and power

“…Using the Kt/V measure created the illusion of allowing patients to direct their own care when, in fact, the nurses were actually dictating this. Nurses were not using qualitative human responses such as how the patient felt – were they itchy, did they have a headache, were they tired, did they sleep or did they experience cramps (Twardowski 2003). Instead, they seemed to be providing care that they wanted but presenting it as ‘what the patient wants’, thus creating an illusion of patient empowerment.…”

History of hemodialyzers' designs

“…200,201 The ideal would be a wearable artificial kidney functioning continuously as natural or transplanted kidneys do, but such a kidney is far ahead on the horizon, if at all possible. During the 20th century, hemodialysis was successfully implemented into clinical practice.…”

“…The optimal time and duration of dialysis need to be established as it seems that the typical routine dialysis sessions are too short and too infrequent. 200,201 The ideal would be a wearable artificial kidney functioning continuously as natural or transplanted kidneys do, but such a kidney is far ahead on the horizon, if at all possible.…”

Improvement of hemodialysis quality by application of various models for adequacy aseessment

“…Kada je isporučena doza dijalize manja od propisane trebalo bi razmotriti: neadekvatan protok krvi (krvni pristup, položaj igle); moguću koagulaciju dijalizatora; grešku pri izračunavanju klirensa dijalizatora; skraćeno vrijeme dijaliznog tretmana (prekidi tokom dijalize koji se ne uračunavaju prilikom računanja, skraćivanje trajanja dijalize i slično); nepravilno uzimanje krvi (uzimanje uzorka krvi prije dijalize koji je razblažen fiziološkim rastvorom ili uzimanjem po započinjanju dijalize; uzimanje krvi za odredivanje postdijaliznih vrijednosti ureje i prije nego je tretman završen ili nakon 5 minuta pošto je tretman završen) [4][5][6][14][15][16].…”