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Part 3: Clinical Experiences |
Department of Internal Medicine, University Hospital, Botucatu School of Medicine, São Paulo State University, São Paulo, Brazil
Correspondence to: D.P. Gabriel, Department of Internal Medicine, Hospital das Clínicas da Faculdade de Medicina de Botucatu, Universidade Estadual Paulista, UNESP, Rubião Júnior, P.O. Box 584, CEP 18618-970, São Paulo, Brazil. dponcegabriel{at}uol.com.br
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ABSTRACT |
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 TOP ABSTRACT PATIENTS AND METHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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Background: In some parts of the world, peritoneal
dialysis is widely used for renal replacement therapy (RRT) in acute kidney
injury (AKI), despite concerns about its inadequacy. It has been replaced in
recent years by hemodialysis and, most recently, by continuous venovenous
therapies. We performed a prospective study to determine the effect of
continuous peritoneal dialysis (CPD), as compared with daily hemodialysis
(dHD), on survival among patients with AKI. Methods: A total of 120 patients with acute tubular
necrosis (ATN) were assigned to receive CPD or dHD in a tertiary-care
university hospital. The primary endpoint was hospital survival rate; renal
function recovery and metabolic, acid–base, and fluid controls were
secondary endpoints. Results: Of the 120 patients, 60 were treated with CPD
(G1) and 60 with dHD (G2). The two groups were similar at the start of RRT
with respect to age (64.2 ± 19.8 years vs 62.5 ± 21.2 years),
sex (men: 72% vs 66%), sepsis (42% vs 47%), shock (61% vs 63%), severity of
AKI [Acute Tubular Necrosis Individual Severity Score (ATNISS): 0.68 ±
0.2 vs 0.66 ± 0.22; Acute Physiology and Chronic Health Evaluation
(APACHE) II: 26.9 ± 8.9 vs 24.1 ± 8.2], pre-dialysis blood urea
nitrogen [BUN (116.4 ± 33.6 mg/dL vs 112.6 ± 36.8 mg/dL)], and
creatinine (5.85 ± 1.9 mg/dL vs 5.95 ± 1.4 mg/dL). In G1, weekly
delivered Kt/V was 3.59 ± 0.61, and in G2, it was 4.76 ± 0.65
(p < 0.01). The two groups were similar in metabolic and
acid–base control (after 4 sessions, BUN < 55 mg/dL: 46 ± 18.7
mg/dL vs 52 ± 18.2 mg/dL; pH: 7.41 vs 7.38; bicarbonate: 22.8 ±
8.9 mEq/L vs 22.2 ± 7.1 mEq/L). Duration of therapy was longer in G2
(5.5 days vs 7.5 days; p = 0.02). Despite the delivery of different
dialysis methods and doses, the survival rate did not differ between the
groups (58% in G1 vs 52% in G2), and recovery of renal function was similar
(28% vs 26%). Conclusion: High doses of CPD provided appropriate
metabolic and pH control, with a rate of survival and recovery of renal
function similar to that seen with dHD. Therefore, CPD can be considered an
alternative to other forms of RRT in AKI.
KEY WORDS: Acute renal failure; daily hemodialysis.
Despite technological advances in renal replacement therapy (RRT), the high mortality rate among critically ill patients with acute kidney injury (AKI) remains an unsolved problem in intensive care medicine (1–3). The dialytic management of these patients is difficult because of the associated hemodynamic instability and multiple organ dysfunction syndrome, and the mortality rate reaches 50% – 70% (4). No consensus has developed in the literature regarding the best method of dialysis or the ideal dialysis dose in AKI. In the developed world, hemodialysis (HD) and peritoneal dialysis (PD) have both been used as therapy in AKI, although intermittent HD is complicated by unstable blood pressure, and PD, by concerns of its inadequacy (5,6).
Four recently published randomized clinical trials and one multicenter observational study call into a question whether outcomes with continuous renal replacement therapy (CRRT) are superior to those of intermittent HD (IHD). None of these studies shows a superior outcome for CRRT as compared with IHD, and several imply a worse outcome with CRRT (7–12).
Schiffl et al. showed that patients with AKI in dialysis, hospitalized in the intensive care unit (ICU), present fewer fatal complications when submitted to daily HD [dHD (weekly Kt/V of 5.8)] as compared with patients receiving alternate-day HD (weekly Kt/V of 3.8). They concluded that dHD was well tolerated by patients, permitting intensive nutritional support without hypotensive episodes. In addition, the mortality rate was lower in this group. One of the reasons for the lower mortality in the dHD group was the higher delivered dose of HD (13).
The mainstay therapy for acute renal failure (ARF) in many developing countries is still PD because of its availability, ease of administration, technical simplicity, lack of a bleeding risk, excellent cardiovascular tolerance, and low risk of hydro-electrolyte disequilibrium (14,15). But PD also has limitations, such as the need for an intact peritoneal cavity, risk of peritoneal infection, occurrence of protein losses, and overall lower effectiveness (16). Because the clearance of small solutes is lower in PD than in HD, concerns have arisen that PD cannot control the AKI patient's uremia (17). However, treatment duration (for example 24 hours) may produce as much solute removal as 4 hours on HD does (18). Studies in the literature report efficient fluid removal and metabolic control in patients on continuous PD (CPD) therapy (6,19–24). However, these are clinical studies and, as such, have limitations such as small sample size and inadequate parameters for measuring catabolism and dialysis adequacy. Also, arbitrarily defined optimum levels of post-dialysis blood urea nitrogen (BUN) and creatinine were used as indices of dialysis adequacy.
Chitalia et al. (6) evaluated two methods of automated PD in ARF patients with mild-to-moderate hypercatabolism. They reported that both methods, CPD and tidal, provide an adequate dialysis dose. Recently, Gabriel et al. (18) conduced a prospective study with 30 ARF patients who were assigned to high-dose CPD (Kt/V of 0.65 per session) using a flexible catheter (Tenckhoff) and automated PD with a cycler. Patients received 236 CPD sessions; weekly normalized creatinine clearance and urea Kt/V values were 110.6 ± 22.5 L/1.73 m2 body surface area and 3.8 ± 0.6 respectively. In 23% of these patients, renal function was recovered; 57% of the patients died. We concluded that high-dose CPD by flexible catheter and cycler was an effective treatment for AKI, providing appropriate metabolic and pH control, and adequate dialysis dose and fluid removal.
Given these limitations, there is a pressing need to re-evaluate the adequacy of PD in AKI using accepted standards and the use of PD as an alternative to other forms of renal replacement therapy in AKI. The present randomized trial was designed to explore the role of CPD as compared with dHD among patients with AKI. The main objective was to comparatively evaluate patient outcomes—mortality rate and recovery of renal function—under both modalities. Secondary endpoints examined were the adequacy of CPD as compared with dHD in relation to controlling metabolic, acid–base, electrolyte, and fluid balance, and the clinical complications of patients treated using these dialytic methods.
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PATIENTS AND METHODS |
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TOPABSTRACTPATIENTS AND METHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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CRITERIA FOR DIALYSIS AND RANDOMIZATION
After solicitation of the assisting medical team, a nephrology evaluation
was performed, consisting of complete physical exam and collection of
laboratory data. Attending nephrologists selected patients for enrollment and
decided when to prescribe dialysis and when to terminate it. The indications
for dialysis were uremic symptoms, BUN in excess of 125 mg/dL, volume
overload, electrolyte imbalance, and refractory acid–base
disturbance.
After enrollment, patients were randomly assigned to receive either CPD or dHD. The randomization scheme was based on random-number tables and was performed by means of consecutively numbered, sealed envelopes. Once randomly assigned, the patient underwent insertion of the appropriate access catheters, and CPD or dHD was started as quickly as possible. Dialysis was terminated upon partial recovery of renal function, defined as restoration of diuresis (more than 1000 mL urine in 24 hours), associated with a progressive fall in serum creatinine and BUN (<4 mg/dL and 50 mg/dL respectively), or change of dialytic method because of mechanical or infectious complications without success under the treatment instituted, or absence of recovery of renal function after 30 days of dialysis, or the death of the patient.
METHODS AND DOSE OF DIALYSIS
CPD: A CPD session was defined as 24 hours of dialysis. Peritoneal
access was established by blind placement of a Tenckhoff catheter, using a
Trocath (B Braun, Bethlehem, PA, U.S.A.) introduced in the midline
infraumbilically by a nephrologist. Prescribed PD dose was determined by the
formula for Kt/V urea (26),
where K is the volume of dialysis solution prescribed in 24 hours (mL)
multiplied by 0.6 (considering the peritoneum at medium transport capacity), t
is treatment duration (1 day), and V is the volume of body urea distribution
in liters by the Watson formula
(27). The prescribed Kt/V
value was 0.65 per session according to a previous study
(18). Exchanges of Dianeal
dialysate [Baxter Healthcare Corporation, Deerfield, IL, U.S.A. (Na, 135
mEq/L; Ca, 3.5 mEq/L; K, 0 mEq/L; Mg, 1.5 mEq/L; acetate, 40 mEq/L; 1.5%
glucose)] were performed using an automated PAC-Xtra 2 cycler (Baxter
Healthcare Corporation). Exchanges of 2 L were used with 35 – 50
minutes' dwell time (a total of 36 – 44 L and 18 – 22 exchanges
daily). In patients with fluid overload, hypertonic fluid (2.5% or 4.25%
glucose) was used. The delivered dose of PD was also determined by the formula
for Kt/V urea, where K is the mean of dialysate BUN (mg/dL) divided by the
mean of plasmatic BUN pre- and post-dialysis (mg/dL), multiplied by drained
volume in 24 hours (mL), divided by the volume of body urea distribution in
milliliters (28).
Blood samples were collected at the beginning and end of each CPD dialysis session to determine creatinine, potassium, pH, and bicarbonate. Plasma albumin was determined every 3 days. Three aliquots (3 mL each) of dialysate effluent were collected at 8-hour intervals during every session to measure urea nitrogen. Protein and albumin were also determined from the effluent every 3 days, as was dialysate white cells. Dialysate was cultured for aerobic and anaerobic bacteria every 3 days using appropriate culture media.
dHD: Access was achieved by inserting a double-lumen catheter in a central venous access (jugular, subclavian, or femoral vein depending on ease of access), at the bedside, blindly, by a nephrologist, under aseptic conditions and local anesthesia. After the procedure, thoracic radiography was used to verify the position of the implanted catheter.
A hemodialysis machine with proportional mixing and volumetric controls (4008F: Fresenius Medical Care, Bad Homburg, Germany) was used. The membrane was of polysulfone with specific performance for each patient after calculation of the Kt/V. The patient's body weight and BUN, the prescribed duration of hemodialysis, and the prescribed blood flow were documented before each session. The actual duration of hemodialysis and the total ultrafiltration volume were recorded at the end of each session. Post-treatment BUN was measured by the slow-flow method (with the blood pump speed reduced to 50 mL/min). Blood samples were obtained from the afferent sampling port before the blood reached the dialyzer.
The adequacy of hemodialysis was determined by urea kinetic modeling, based on the formula Kt/V, in which K denotes the rate in vivo of urea clearance by the dialyzer in milliliters per minute, t the duration of the treatment session in minutes, and V the distribution volume of urea within the patient in liters. The prescribed Kt/V value was 1.2, a value widely considered to indicate adequate hemodialysis in patients with end-stage renal disease, and a value used in study by Schiffl (13) et al. The delivered dose of dHD was determined based on the single-pool Kt/V value, corrected for ultrafiltration, but not for the reappearance of urea nitrogen (29). Bicarbonate, potassium, and sodium in the dialysate were adjusted according to individual requirements.
A correction factor of 0.8 was used for the final calculation of delivered Kt/V in CPD and dHD, as proposed by Himmelfarb et al. (30), because in AKI patients, urea distribution volume exceeds total body water in 20% of patients.
MONITORING AND ANALYSIS OF SAMPLES
Patients were treated and monitored according to accepted practice for
control of glucose and sodium in intensive care. The severity of illness was
determined according to the score on the Acute Physiology and Chronic Health
Evaluation (APACHE) II and the Acute Tubular Necrosis Individual Severity
Score (ATNISS) on the day of the first nephrology evaluation. Other variables
included the cause of AKI, presence or absence of sepsis and of oliguria at
initiation of dialysis, the reason for dialysis, and the number and duration
of dialysis sessions. Parenteral nutrition was initiated if oral or enteral
intake of nutrients was deemed to be insufficient. Anthropometric
measurements—weight, height, and body surface area calculated from the
Du Bois and Du Bois formula
(31)—were obtained
before initiation of dialysis. Mobile patients were weighed on digital scale;
in immobilized patients, two different formulas were used
(32).
Urea nitrogen, creatinine, potassium, and albumin were measured using the specific reactive method by dry chemistry technology and the Vitros 950 analyzer (Johnson and Johnson, Seattle, WA, U.S.A.). Serum bicarbonate and pH were measured using an ABL 555 blood gas analyzer (Radiometer A/S, Copenhagen, Denmark). Protein in dialysate effluent was determined using the specific reactive method by dry chemistry technology in spinal fluid. Protein electrophoresis using Hydragel kits (Sebia, Norcross, GA, U.S.A.) and an automatic multiparametric system for electrophoresis in agarose was performed to quantify albumin in dialysis effluent.
STATISTICAL ANALYSIS
We calculated that, with at least 60 patients for whom adequate data were
available in each treatment group, the study would have a statistical power of
80% to detect an absolute difference in mortality of 20% between the
groups.
Results are presented as medians or means ± standard deviation, according to the normality characteristics of each variable, with a 5% (p < 0.05) significance level.
For parametric variables, the independent t-test was used to compare parametric variables between the two groups, and ANOVA, followed by the Newman–Keuls test, was used for multiple comparisons between groups. For nonparametric variables, comparisons were performed using the Wilcoxon test and the Kruskal–Wallis test followed by the Dunn method respectively. At the end of the study, a survival curve of patients in each group was prepared.
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RESULTS |
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TOPABSTRACTPATIENTS AND METHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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Of the remaining 120 patients, 60 received CPD and 60 received dHD (Figure 1). The baseline characteristics of the two treatment groups were similar (Table 1). Mean of age of the patients was 64.2 ± 19.8 years in the CPD group and 62.5 ± 21.2 years in the dHD group. Both patients groups consisted predominantly of men (72% vs 66%). The APACHE II score was 26.9 ± 8.9 (CPD) versus 24.1 ± 8.2 (dHD), and the ATNISS was 0.69 ± 0.2 versus 0.68 ± 0.22. There was no difference in the number of patients who received noradrenaline, dobutamine, or dopamine (61% vs 63%). Sepsis was the main comorbidity (42% vs 47%), ischemic ATN was the predominant cause of AKI (83% vs 88%), and uremia or azotemia was the main indication for dialysis (61% vs 63%). The dHD group underwent dialysis therapy for longer than the CPD group did (5.5 days vs 7.5 days, p = 0.02).
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Table 2 shows the dialysis dose parameters. Delivered dose was significantly lower in the CPD group than in the dHD group (Kt/V: 3.59 ± 0.61 vs 4.76 ± 0.65), but ultrafiltration per session did not differ significantly between the treatment groups (2.1 ± 0.7 L in CPD vs 2.4 ± 0.72 L in dHD, p = 0.39).
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The two groups were similar in metabolic and acid–base control. The patients' BUN, serum creatinine, bicarbonate, and pH levels stabilized after 3 or 4 sessions of dialysis. The mean values, after 4 sessions, for BUN and serum creatinine were 46 ± 18.7 mg/dL (CPD) versus 52 ± 18.2 mg/dL (dHD) and 4.6 ± 0.98 mg/dL (CPD) versus 5.5 ± 1.28 mg/dL (dHD) respectively, and bicarbonate levels were 22.8 ± 8.9 mEq/L versus 22.2 ± 7.1 mEq/L [Figures 2(a) to 2(c)]. Potassium, sodium, and glucose levels were not significantly different between the two groups [Figures 2(d) to 2(f)]. Patients treated with CPD did not present uncontrolled hyperglycemia or hypernatremia during the therapy.
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Overall mortality was not different between patients treated with CPD and dHD (58% vs 53% respectively, p = 0.48). Of the 120 patients, 31% had complete or partial recovery of renal function. Of the 24 patients in the CPD group who survived, only 4 remained on dialysis; of the 29 patients in the dHD group who survived, 6 did not recover renal function after 30 days of therapy, and they remained on dialysis (17% vs 21%, p = 0.45). The two groups were similar in their rates of mechanical and infectious complications. Peritonitis occurred in 11 patients in the CPD group (18%); in 4 of the 11 (7% of the total), the Tenckhoff catheter was removed, and the dialysis method was changed because of lack of improvement in laboratory parameters (effluent cell counts) after 5 days of specific treatment for peritonitis. Pseudomonas aeruginosa, Staphylococcus aureus, and fungi were the main causative organisms. Mechanical complications were considered mild in the CPD group after 24 hours of dialysis, because they did not cause a change of method or dialysis dose. In the dHd group, only 1 patient had to be switched to CRRT because of hemodynamic instability. Table 3 summarizes complications and outcomes in the AKI patients treated with CPD and dHD. At 30 days, there was no difference in patient survival between the groups (Figure 3).
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DISCUSSION |
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TOPABSTRACTPATIENTS AND METHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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The two groups were similar with regard to BUN, creatinine, bicarbonate, and pH levels. After 3 and 4 sessions, BUN and creatinine were stabilized at values below 55 mg/dL and 4 mg/dL respectively. Similar encouraging results were observed for pH and bicarbonate: after 3 sessions, these values were stabilized at about 7.4 mEq/L and 22 mEq/L respectively. Both dialysis modalities provided restoration and maintenance of fluid and electrolyte balance (mean ultrafiltration of about 2.2 L per session and K less than 4 mEq/L after 1 session). In this series, patients were treated and monitored according to accepted practices for control of glucose and sodium in intensive care. The two groups were similar with respect to control of plasma glucose and sodium during dialysis therapy. Surprisingly, patients treated with CPD did not present uncontrolled hyperglycemia or hypernatremia. We observed no significant difference in mortality rate between the two groups (53% vs 58%, p = 0.48), and these mortality rates were similar to those described in the literature (2–4,11–13). After 30 days of dialysis treatment, patient survival was similar between the two groups at about 50%.
Few studies in the literature compare different methods of dialysis in AKI, and those that have made a comparison have produced conflicting results (3,5–11,15). We did not find studies that compared CPD with dHD. Adequacy of therapy for AKI has not yet been completely defined, but it is commonly agreed that renal support therapies should provide correction of biochemical abnormalities, restoration and maintenance of fluid and electrolyte balance, and maintenance of physiologic parameters within levels adequate to preserve organ function and to permit functional recovery. Nevertheless, several questions are still unanswered and require continued discussion.
First, is a treatment for AKI capable of achieving the foregoing goals currently available?
The answer to that question cannot be simple or complete (33). Despite a significant attempt to find an optimal therapy, it has become clear that the average mortality of patients with AKI has not improved significantly over time (34). Therapies for AKI provide renal support rather than complete renal replacement, because they offer only a partial and limited substitution of the multiple functions of the kidney (35), and patient conditions are becoming extremely complex, meaning that a generalized prescription of therapy cannot reasonably be made for all individuals (36).
Four recently published randomized clinical trials and one multicenter observational study call into a question whether outcomes with CRRT are superior to those with IHD. None of those studies shows a superior outcome for CRRT as compared with IHD, and several imply a worse outcome with CRRT (7,12).
Schiffl et al. showed that patients with AKI on dialysis, hospitalized in the ICU, present fewer fatal complications when receiving dHD (weekly Kt/V of 5.8) as compared with alternate-day HD (weekly Kt/V of 3.8). They concluded that dHD was well tolerated by patients, permitting intensive nutritional support without hypotensive episodes. The mortality rate was also lower in the dHD group. One of the reasons for the lower mortality in dHD was the higher delivered dose of HD (13). In summary, comparisons of CRRT and IHD have so far failed to demonstrate the superiority of any technique in terms of survival, and there is current evidence to support the use of dHD (37).
Next, can PD still be considered an option for the treatment of AKI, especially in specific regions of the world where access to sophisticated forms of RRT is limited?
The PD modality includes a series of different techniques. Based on the characteristics of the peritoneal membrane, various equilibration levels between dialysate and plasma can be observed at similar dialysate flows. In general, however, dialysate flow—and thus dwell times and small-solute clearances—are known to present a steep progressive correlation that tends to plateau at high dialysate flows (38). In the first region of this relationship, the clearance is limited by dialysate flow; in the second region, clearance is limited by membrane permeability and area (39). In this first domain, a 2-L exchange lasting approximately 1 hour, as we propose, can achieve a saturation of spent dialysate in the range of 50%. Therefore, over 24 hours, an average urea clearance of approximately 24 L can be expected if a 2-L/hour regime is applied. This calculation may lead to a Kt/V of 0.65 in a patient with a body weight between 65 kg and 70 kg. A continuous and daily regime of this kind should provide a weekly Kt/V of 4.55, which is close to the value observed in the present study. Comparing this type of PD with dHD involving a single-session Kt/V of 1, similar levels of standardized Kt/V can be achieved (40). This calculation provides a framework for equivalency of IHD and CPD in terms of small-solute clearance. If this equivalency is the case, the theoretical approach to blood purification may be adequate, and a kinetic rationale for the application of PD in AKI can be found.
Studies in the literature report efficient fluid removal and metabolic control in patients on CPD therapy (6,16,18–24). However, these are clinical studies, and they have limitations such as small sample size and inadequate parameters for measuring catabolism and dialysis adequacy. Also, arbitrarily defined optimum levels of post-dialysis BUN and creatinine were used as indices of dialysis adequacy.
Therefore, PD for AKI is still the mainstay therapy in many developing countries because of its availability, ease of administration, technical simplicity, lack of a bleeding risk, excellent cardiovascular tolerance, and low risk of hydro-electrolyte disequilibrium (19,20,41). According to data from the Latin American Society of Nephrology and Hypertension, presented in oral form at the World Congress of Nephrology in 2007 published, CPD is used to treat AKI patients in 35% of all centers.
In the present study, we observed no significant differences in metabolic, acid–base, and electrolyte control and in fluid status between patients treated with CPD and with dHD. Adequacy parameters in the two modalities were similar and effective in AKI, although delivered weekly Kt/V was significantly lower in the CPD group than in the dHD group (3.5 vs 4.8, p < 0.01). Adequacy of dialysis dose in AKI is a subject of controversy for many reasons (30,34,35). Recent studies showed that dialysis dose is one of the major factors contributing to patient survival (13), but no satisfactory marker of dialysis adequacy in AKI has been found (42–45).
Other aspects should be considered, including the lower efficiency observed in larger patients and the limited capacity to modulate fluid removal with PD. It is also true, however, that this PD regime is not the most efficient; clearance per exchange can be increased if shorter dwell times are applied. Recently, Phu et al. (5) reported that intermittent PD failed to control acidemia and levels of creatinine, which may have been related to a higher mortality rate in that group than in a hemofiltration group. However, those authors used intermittent PD, delivered by rigid catheter, with manual exchanges and a too-short dwell time (less than 15 minutes), providing inadequate solute removal.
Chitalia et al. (6) proposed a high volume of dialysate. Those authors evaluated two methods of automated PD in AKI patients with mild-to-moderate hypercatabolism. They reported that both methods, CPD and tidal, were adequate with regard to dialysis dose. Recently, Gabriel et al. (15) conduced a prospective study with 30 ARF patients who were assigned to high-dose CPD (Kt/V of 0.65 per session) delivered using a flexible catheter (Tenckhoff) and a cycler. Patients received 236 CPD sessions; weekly normalized creatinine clearance and Kt/V urea values were 110.6 ± 22.5 L/1.73 m2 body surface area and 3.8 ± 0.6 respectively. With regard to ARF outcome, 23% of patients recovered renal function, and 57% died.
We concluded that high-dose CPD by flexible catheter and cycler is an effective treatment for AKI, allowing for appropriate metabolic and pH control, and adequate dialysis dose and fluid removal. Considering such levels of efficiency, CPD may become an interesting alternative to HD or CRRT in the treatment of AKI (15,18,33).
Peritoneal dialysis also has other limitations, such as the need for an intact peritoneal cavity, risk of peritoneal infection, mechanical complications, and occurrence of protein losses (15,18,21,23,24,33,46).
Another aspect to consider is the logistics of the treatment. Patients with AKI are frequently treated in the ICU, where the risk for infection is greater. Furthermore, these patients are often mechanically ventilated, which presents increased intra-abdominal pressure (47,48). Peritoneal dialysis can worsen this situation, leading to impaired respiratory or cardiac performance. In the present study, we did not evaluate respiratory performance in relation to the method of dialysis. Patients were treated and monitored according to accepted practices for control of glucose and sodium in intensive care.
Several studies have shown that PD leads to large protein losses, as high as 48 g per session (18,49); even so, this knowledge should not disqualify PD from being the method of choice for AKI, because no significant reductions in serum albumin levels are observed (15,18, 49–51). This finding was also confirmed in the present study.
Concerning infectious complications, we observed no significant differences between the two groups. Peritonitis levels were similar to those reported in the literature, at about 20%, and in 4 cases the catheter was removed, and the dialysis method changed (15,16, 18–24). Fungi, Pseudomonas aeruginosa, and Staphylococcus aureus were the most common infecting organisms. With regard to mechanical complications, 15% of patients presented early leakage (after fewer than 24 hours of dialysis); these patients were excluded from the protocol analysis. After 24 hours of CPD, only 5% of patients showed mechanical complications, and those complications were considered mild, because they did not cause interruption of the dialysis method.
In the present series, the mortality rate and the rate of recovery of renal function were both similar between the two groups. There was no significant difference in patient survival after 30 days of treatment; the rate was about 50% with both modalities.
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CONCLUSIONS |
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TOPABSTRACTPATIENTS AND METHODSRESULTSDISCUSSIONCONCLUSIONSREFERENCES |
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Historically, PD has been used with success for the treatment of AKI. Where HD and CRRT have become available, PD has been almost abandoned. However, a rationale still exists for the use of PD in critically ill patients, especially in hospitals where more sophisticated technologies are not available. The theoretical approach to dialysis adequacy suggests that careful prescription and accurate measurement of efficiency may contribute to adequate treatment in most patients. Limitations are imposed by a low rate of ultrafiltration and a high chance of infection. Nevertheless, new cyclers and new catheters for CPD modalities may help to overcome some of the classical limitations and may help to maintain PD as a suitable alternative for the treatment of AKI.
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