Acute renal failure requiring dialysis in very old critically ill patients

Acute renal failure (ARF) is common in critical care patients. One risk factor for ARF is age. However, access to dialysis is often limited in older patients, due to their worse prognosis. We report our experience in dialyzing old patients, and compare them with younger patients with ARF in our unit. Since September 1994, we recorded all dialyzed patients, treated with intermittent dialysis (IHD), continuous dialysis (CRRT) or both, depending on clinical decisions. For IHD we use a Fresenius 4008 E machine and polysulfone dialyzers. For CRRT, we first used a DM 08 Fresenius machine and, from 2001, a Diapact-CRRT Braun machine, with polysulfone hemofilters. Since 1994, we have had 163 patients, 68.4% males, mean age 60 (range 15–92) years. Mean APACHE II score at admission was 21.6. Eighty-three percent needed mechanical ventilation, 53% were primarily surgical and in 74% there was a relevant infection or sepsis.

From the total, 52 patients (32%) were older than 75 years (mean age 83 ± 4 years). In this group, 79% were male, 83% needed mechanical ventilation, 54% received nephrotoxic agents, including radiocontrast, 58% were primarily surgical and 72% had sepsis. Compared with younger patients, older patients were more often males, and had higher APACHE score (23.2 versus 20.6, P < 0.05) and mortality (55.8% versus 40.5%, P < 0.05).

In the older group, the main differences between survivors and nonsurvivors were the incidence of sepsis (79% in nonsurvivors versus 60% in survivors), and the type of patient (nonsurvivors 69% surgical versus survivors 43% surgical). Age, use of mechanical ventilation, and APACHE score were not different between survivors and nonsurvivors. Regarding modality of dialysis, CRRT was used in 13 patients, with 11 deaths (84%). In contrast, the mortality of younger patients treated with CRRT was 47%. As for ARF outcome, 100% of nonsurvivors maintained ARF at death. In contrast, none of the survivors required dialysis at discharge of the hospital. Throughout the years, dialysis was more often considered: 52% of the older patients dialyzed were admitted after 2001, and more often also, CRRT was used (only two CRRT before 2001 in the older group).

In conclusion, ARF is common in old patients. Even though ARF and dialysis are associated with high mortality, still 44% of old patients submitted to acute dialysis survive, and are discharged free of dialysis. With time, more old patients will be admitted to ICUs and treated with dialysis. As other authors have concluded, age should not be used as an isolated factor for deciding to treat ARF with dialysis.