Chapter 8 – Renal Replacement Therapy




Abstract




A 72-year-old man is brought to the emergency department from his skilled nursing facility for shortness of breath and altered mental status. He is admitted to the medical intensive care unit (ICU) with pneumonia and septic shock. He receives appropriate antibiotics, intravenous fluids, and vasopressor therapy. He requires intubation for failure to protect his airway. By hospital day 4, his shock has resolved but he remains on the ventilator. He develops acute on chronic renal failure owing to septic acute tubular necrosis. He is anuric and grossly volume overloaded. His past medical history includes coronary artery disease, congestive heart failure, type 2 diabetes mellitus, chronic kidney disease stage III, and dementia.





Chapter 8 Renal Replacement Therapy


Hassan Suleiman and Paul McCarthy





Case


A 72-year-old man is brought to the emergency department from his skilled nursing facility for shortness of breath and altered mental status. He is admitted to the medical intensive care unit (ICU) with pneumonia and septic shock. He receives appropriate antibiotics, intravenous fluids, and vasopressor therapy. He requires intubation for failure to protect his airway. By hospital day 4, his shock has resolved but he remains on the ventilator. He develops acute on chronic renal failure owing to septic acute tubular necrosis. He is anuric and grossly volume overloaded. His past medical history includes coronary artery disease, congestive heart failure, type 2 diabetes mellitus, chronic kidney disease stage III, and dementia.



Acute kidney injury (AKI) is a common occurrence in the ICU. Approximately 30% of patients admitted to the ICU will develop AKI. Of all patients admitted to the ICU, about 13% will develop AKI requiring some form of renal replacement therapy (RRT).1, 2 Dialysis can be offered via several modalities in the ICU. Continuous RRT has emerged as a popular therapy for severely critically ill patients who, in the past, may not have tolerated conventional hemodialysis. This advancement in technology has led to the ability to provide dialysis to older and sicker patients. Although the occasional patient may have previously expressed their views regarding dialysis, many families and legally authorized representatives are often faced with making the complex decision of whether to initiate dialysis without the patient’s input. A discussion involving the ICU team and the nephrologist regarding expectations for mortality, renal recovery, functional status, and quality of life (QoL) on dialysis are required. The implications of developing severe AKI requiring RRT in the ICU are discussed in this chapter. Outcomes data should be used to guide discussion with patients and their decision makers.



8.1 AKI Requiring RRT: Outcomes of Renal Recovery and Mortality


AKI requiring RRT carries a high short-term risk of mortality. This serious complication is often a reflection of multiorgan dysfunction rather than a single disease process in the critically ill patient. Nevertheless, AKI is an independent risk factor for increased mortality in the ICU. A large, prospective multicenter cohort study of 17,126 patients found that the in-hospital mortality for patients with AKI requiring RRT was more than 60% compared with 15.6% for control participants matched for age, severity of illness, and treatment center.3 A prospective cohort study found that at 1 year, complete renal recovery (an estimated glomerular filtration rate that is within 25% of the initial estimated glomerular filtration rate) occurred in fewer than one-half of the 1,292 patients enrolled (48.4%). Dialysis dependence was reported in 32.6% of patients. ICU mortality was 54.6% and increased to 72.1% at 3 years, further illustrating both high short- and long-term mortality.4


Despite advances in the delivery of RRT, there is no specific treatment for AKI and management remains largely supportive. The increased risk of developing chronic kidney disease and death are important prognostic implications of AKI requiring RRT.



8.2 Quality-of-Life Outcomes of AKI Requiring RRT


QoL is a vital patient-centered outcome that should be discussed with the patient or surrogate decision maker when determining whether RRT should be initiated. Many patients have strong views about life support and being kept alive by machines. It is paramount to address QoL concerns, as well as patients’ and their decision maker’s preconceived notions about dialysis.


A prospective cohort study compared ICU patients treated with RRT for AKI with matched patients without AKI or RRT (non–AKI-RRT) over 1 year. Patients with AKI requiring RRT alive at 1 year and 4 years were matched with non–AKI-RRT survivors from the same cohort. QoL was assessed using the EuroQoL-5D and the Short Form-36 survey before ICU admission and at 3 months, 1 year, and 4 years after ICU discharge. Of 1,953 patients, 121 had AKI requiring RRT. Long-term QoL assessed via both the EuroQoL-5D and the Short Form-36 survey were surprisingly comparable between those with AKI requiring RRT and the non–AKI-RRT group at 1 and 4 years, with no statistically significant differences detected between the groups in any subcategory of either survey. It is important to note, however, that the QoL of both patients with AKI needing RRT and non–AKI-RRT ICU survivors were lower than that of the general population.5


The POST-RENAL study was an extended follow-up study to obtain outcomes data on patients diagnosed with AKI who required RRT from a randomized controlled trial assessing RRT intensity. POST-RENAL used the Short Form-12 questionnaire to assess QoL in patients with AKI requiring RRT who were ICU survivors. There were 282 patients with Short Form-12 questionnaire data who were compared with 6,330 patients from the AusDiab study. POST-RENAL patients were found to have lower physical component scores (mean 40.0 vs 49.8; p < .0001) as well as lower mental component scores (mean 49.8 vs 53.9; p < .0001), which persisted after matching the participants on the basis of age, sex, and renal function.6


Special attention should be paid to elderly patients in nursing homes progressing to end-stage renal disease (ESRD). A 2009 study identified 3,702 nursing home residents in the United States starting dialysis. Functional status was assessed using the Minimum Dataset Activities of Daily Living scale (scores ranging from 0 to 28 assessing degree of dependence in seven activities of daily living, with high scores indicating greater difficulty). The median Minimum Dataset Activities of Daily Living score was 12 at 3 months before the initiation of dialysis and increased to 16 within the first 3 months of starting dialysis. Maintenance of baseline functional status at 3 months occurred in only 39% of patients. Furthermore, by 1 year, 58% of patients had died and functional status had been maintained in only 13% of patients.7


Overall, QoL data on ICU survivors requiring RRT are conflicting. It can be conferred that ICU survivors will most likely have a lower QoL than the general population. Living with chronic dialysis is at best unlikely to improve QoL and at worst can decrease physical and mental performance. Patients in nursing homes requiring long-term dialysis experience high mortality and very few maintain their baseline functional status at 1 year.



8.3 Risk of ESRD After AKI Requiring RRT


Patients and families often want to know what to expect regarding the potential long-term need for dialysis. Approximately 2%–30% of patients with AKI requiring RRT will require chronic dialysis. Preexisting chronic kidney disease and AKI severity were found to have the strongest association with incident chronic dialysis.8 Data from the POST-RENAL study demonstrated that, of the 1,464 patients included in the original trial, only 810 patients (55%) survived to 90 days after hospital discharge. Approximately 5% were dialysis dependent at 2.6 years after discharge.9 A separate study of ICU patients admitted after major surgery identified acute-on-chronic kidney disease as the strongest independently associated variable in progression to ESRD (incidence of 22.4 per 100 person-years and associated with a 123-fold increased risk compared with patients without AKI).10 Individual risk factors for chronic dialysis should be assessed on a case-by-case basis with special emphasis placed on preexisting chronic kidney disease.

Only gold members can continue reading. Log In or Register to continue

May 29, 2021 | Posted by in CRITICAL CARE | Comments Off on Chapter 8 – Renal Replacement Therapy
Premium Wordpress Themes by UFO Themes