Use of peritoneal dialysis (PD) for the treatment of acute kidney injury (AKI) in adults

INTRODUCTION — Dialysis-requiring acute kidney injury (AKI) is most commonly treated with hemodialysis (HD) or hemofiltration. However, peritoneal dialysis (PD) is also a viable option for treatment of dialysis-requiring AKI, particularly among patients with severe hemodynamic compromise or coagulation abnormalities that make HD unsafe, or among patients who are treated where HD and continuous kidney replacement therapy (CKRT) are not widely available [1-6].

The advantages, technical aspects, and complications of PD for the treatment of AKI (also called acute PD) in adults are presented here. Other modalities for and aspects of management of dialysis-requiring AKI are presented elsewhere:

●(See "Kidney replacement therapy (dialysis) in acute kidney injury in adults: Indications, timing, and dialysis dose".)

●(See "Continuous kidney replacement therapy in acute kidney injury".)

●(See "Urgent-start peritoneal dialysis".)

●(See "Dialysis-related factors that may influence recovery of kidney function in acute kidney injury (acute renal failure)".)

●(See "Overview of the management of acute kidney injury (AKI) in adults".)

●(See "Pediatric acute kidney injury: Indications, timing, and choice of modality for kidney replacement therapy".)

ADVANTAGES OF PD FOR AKI — There are several advantages of PD in the setting of AKI (acute PD):

●Logistical ease – Acute PD can be performed with ease in a center that has capabilities and staff trained for urgent-start PD. The relative simplicity and lower infrastructure requirements of PD make it less labor-intensive and more cost-effective than hemodialysis (HD) or hemofiltration. Details regarding infrastructure for urgent-start PD are presented elsewhere. (See "Urgent-start peritoneal dialysis".)

●Improved hemodynamic tolerance – Acute PD can be performed as a continuous or intermittent modality. Due to the mechanism of clearance, the removal of solutes (eg, urea) and fluid is gradual, which improves its tolerability among patients who are hemodynamically unstable [3,7,8]. In addition, compared with HD and hemofiltration, PD may be less inflammatory due to the absence of blood exposure to synthetic dialysis membranes.

●Lower risk of dialysis disequilibrium syndrome – Slow removal of solutes with PD enables a gradual decline in nitrogenous waste, thereby lowering the risk of dialysis disequilibrium syndrome. With daily continuous PD, it typically takes three to four days to achieve a steady-state in blood levels of creatinine, urea, potassium, and bicarbonate [3,8]. (See "Dialysis disequilibrium syndrome".)

●Mitigation of bleeding risk – PD does not require procedural anticoagulation, therefore making it advantageous among patients at a high risk for bleeding with anticoagulation (eg, internal or intracerebral bleed, major trauma, immediate postoperative state). Although HD and hemofiltration may be performed without the use of anticoagulation among patients who are bleeding, this is not without risk of recurrent clotting of the extracorporeal circuit. (See "Anticoagulation for the hemodialysis procedure", section on 'Patients at high risk for bleeding'.)

●Advantages among malnourished patients – PD fluid can serve as a source of calories (from glucose) among patients who are malnourished. However, protein losses (protein clearance) from the peritoneal membrane into the peritoneal dialysate can be highly variable among patients. Thus, the benefit of positive caloric balance from glucose can be advantageous only among malnourished patients who do not have excess protein leakage into their dialysate [9,10].

Additionally, the daily obligate fluid gain among malnourished patients who are on an enteral liquid diet or on total parenteral nutrition can be substantial. Such gains are easier to mitigate by daily fluid removal on PD compared with intermittent HD.

IDEAL CANDIDATES — The indication for initiating kidney replacement therapy in patients with AKI and selection of ideal candidates for acute PD are presented elsewhere. (See "Kidney replacement therapy (dialysis) in acute kidney injury in adults: Indications, timing, and dialysis dose", section on 'Peritoneal dialysis'.)

DIALYSIS ACCESS — Dialysis access is one of the important determinants of a successful PD procedure [6,11]. We prefer to place a flexible double-cuff PD catheter, where available. Other catheter options include flexible single-cuff, semi-rigid, rigid, or improvised catheters (eg, nasogastric tube, intercostal drainage catheters). A PD catheter can be inserted using the modified-Seldinger technique, laparoscopy, or laparotomy depending upon local procedural expertise (table 1).

Preferred access in resource-rich settings — For acute PD, we prefer a flexible, tunneled double-cuff PD catheter, preferably placed either by laparoscopy or laparotomy. Among patients with contraindications to general anesthesia or who need dialysis urgently (before surgery can be scheduled), a trained nephrologist or a surgeon can place the catheter at the bedside using the modified-Seldinger technique [3,5,8,10,12-22].

Although there is little published evidence that flexible catheters are superior to other catheters, in the authors' experience, flexible catheters provide better flow rates and are associated with fewer complications [1,5,11,23,24].

We favor flexible catheters for several reasons. Compared with semi-rigid or rigid catheters, flexible catheters have:

●A high frequency of functioning immediately upon placement

●A decreased incidence of infection

●No need for repeated catheter placement procedures (semi-rigid and rigid catheters need be replaced every 72 hours or after every third PD session)

●A minimal risk of injury to the bowel or other intraperitoneal organs

●Greater comfort for the patient

●A better performance with automated cyclers (ie, fewer alarm triggers) leading to fewer interruptions

Flexible double-cuff PD catheters are the most commonly used. These catheters are preferable to semi-rigid catheters because they have a larger luminal diameter and additional side apertures. These design features result in better dialysate flow rates and less frequent obstruction. They are also less prone to leakage and are associated with a lower incidence of peritonitis [12]. In addition, in the event that the patient does not recover from AKI, then the catheter may be used for chronic dialysis without the need for a new access placement procedure.

The technique of placement is highly dependent upon local expertise and resources (table 1) [25]. No one method is superior to others. The modified-Seldinger approach is a blind procedure and, therefore, contraindicated in those who have had open abdominal surgery using a midline approach or who have a high likelihood of having intra-abdominal adhesions. However, this bedside technique is advantageous in critically ill and other patients who are at a high risk for complications of general anesthesia. We use prophylactic antibiotics prior to placement of the PD catheter, similar to the practice in chronic PD patients. (See "Placement of the peritoneal dialysis catheter".)

Alternate access in resource-limited settings — In resource-limited settings, our preference remains for flexible double-cuff catheters, where available. When flexible catheters are not available, we use semi-rigid catheters. If neither flexible nor semi-rigid catheters are available, then we use rigid or improvised catheters. Examples of improvised catheters include nasogastric tubes and intercostal drainage catheters. All catheters can either be placed surgically (by laparoscopy or laparotomy) or at the bedside using the modified-Seldinger technique (table 1).

The improvised catheters have fewer side apertures and are less suitable for tunneling, thereby increasing the propensity for dialysate leakage. In addition, they lack cuffs that prevent bacterial migration, which increases the risk of infection [12,26].

Rigid and improvised catheters may result in bowel perforation at the time of catheter insertion, and thereafter the risk of perforation increases proportionately with the length of time that they remain inserted. The risk of infection and organ injury are higher for such catheters that remain in place for longer than 72 hours. However, rigid or improvised catheters may be lifesaving when other catheter options or dialysis modalities are unavailable.

DIALYSATE SOLUTION — Peritoneal dialysates used in the setting of AKI are similar to those that are used in the setting of end-stage kidney disease. Ideally, commercially prepared dextrose-based solutions should be used. However, in resource-limited settings, cost-effective and improvised options may need to be formulated.

Preferred dialysate in resource-rich settings — We use the same standard dextrose-based PD solutions that are used for chronic PD. Other types of peritoneal dialysates (eg, amino acids, icodextrin) have a limited role in the AKI setting.

Dialysate solutions should be warmed to body temperature prior to infusion to avoid discomfort and to enhance solute transport.

Among patients with shock or liver failure, we use bicarbonate-containing rather than lactate-containing dialysates, where available. This is due to the suboptimal conversion of lactate to bicarbonate in liver failure and shock, thereby potentially leading to metabolic acidosis [13,27,28]. Additional details regarding peritoneal dialysates are presented elsewhere. (See "Prescribing peritoneal dialysis", section on 'Dialysate'.)

Alternate dialysate in resource-limited settings — We agree with the International Society for Peritoneal Dialysis (ISPD), which recommends the following types of PD fluid in the following order of preference:

●Commercially prepared solutions

●Locally prepared fluid made in an approved and certified aseptic unit/pharmacy. These products would have a limited expiry time as approved by the manufacturing unit according to local regulations and standards that can vary by type of environmental controls in use, equipment, testing, personnel training, and other factors. In the United States, for example, the regulatory framework is provided in United States Pharmacopeia with additional professional resources available that require subscription. Compounding guidance at health care facilities regulated in the United Kingdom is available from the Royal Pharmaceutical Society.

●Solutions prepared in a clean environment with the minimum number of punctures and least number of steps. This fluid should be used immediately.

In situations where dialysis fluids are not available or are unaffordable, dialysis fluids can be prepared using available intravenous fluids.

Commercially prepared solutions are usually produced to high standards with careful precautions to guard against bacterial and endotoxin contamination. Locally prepared solutions carry the potential risks of contamination and mixing errors, which may be life-threatening. However, when necessary, these solutions can be prepared using intravenous fluids as a base solution, preferably in a pharmacy manufacturing unit, or otherwise within the clinical center where they will be used. Lactated Ringer's solution or bicarbonate-buffered 0.45 percent saline (ie, 0.45 percent saline with 30 mEq/L of sodium bicarbonate) are preferred intravenous solutions to be used as peritoneal dialysate. Solutions that are prepared at the clinical center should either be used immediately or discarded.

SELECTING PD MODALITIES FOR AKI — Acute PD can be performed either intermittently or continuously, depending upon the amount of fluid and solute removal desired. It can be performed either manually or using an automated cycler, similar to the procedure among patients who require PD for end-stage kidney disease [3,6,8,11,29]. (See "Evaluating patients for chronic peritoneal dialysis and selection of modality", section on 'Available modalities' and "Prescribing peritoneal dialysis", section on 'Delivery strategy'.)

Available modalities — The available dialysis modalities discussed below may be performed either manually or with a cycler. However, certain modalities, such as tidal PD and high-volume PD, can be labor-intensive and prone to infectious complications when performed without a cycler.

Inflow volume refers to the amount of dialysate instilled into the peritoneal cavity with each exchange. Dialysate flow rate is the amount of dialysate instilled per hour. As examples, with a prescription of 24 cycles of 2100 mL over 24 hours, the inflow volume and dialysate rates are both 2100 mL and 2100 mL per hour. However, with the same prescription of 2100 mL exchange over 24 hours, but with 20 cycles, the inflow volume is 2100 mL but the dialysate flow rate is 1750 mL per hour. Additional details regarding specifics of each modality are discussed below:

●High-volume PD (HVPD) – An automated cycler is used to perform frequent exchanges (eg, 18 to 22 exchanges per day) [3,8,29]. This technique provides the greatest small-solute clearance of any PD technique and probably the greatest ultrafiltration rate. However, it makes use of large volumes of dialysate, thereby increasing the cost of the procedure. In addition, due to the rapidity of the exchanges, peritoneal surface contact time with the dialysate is reduced, and, therefore, clearance of middle- and larger-molecular-weight solutes is lower compared with that achieved by methods using slower exchanges [5,6,15].

●Continuous equilibrated PD (CEPD) – This technique is similar to chronic ambulatory PD, except that CEPD is performed in patients who are hospitalized. This technique helps maintain a fairly stable fluid and solute balance. It can be performed manually or using a cycler about four times daily with dwell times of four to six hours [1,3,8,22,30-32].

●Acute intermittent PD (AIPD) – AIPD usually involves short dwell times with 1- to 3-liter inflow volumes and dialysate flow rates of 1 to 4 liters per hour. The session may last 12 to 24 hours and occur every other day.

●Tidal PD (TPD) – This technique is a form of PD in which 10 to 50 percent of the dialysate (also called "residual volume") is left behind in the peritoneal cavity. This allows for rapid exchanges, using a cycler, of approximately one-half the peritoneal fluid instilled, thereby improving overall solute clearance. This increase in solute clearance is primarily due to the increase in the frequency of exchanges using the additional time that would have otherwise been spent draining the dialysate completely [2,14,33,34]. TPD is often used to reduce pain that occurs at the very end of dialysate drainage, which is usually due to irritation of intraperitoneal tissue by the catheter, and is most severe towards the end of the drainage procedure. This pain can be minimized by the tidal volume acting as a physical buffer between the catheter and the intraperitoneal tissue.  

●Continuous flow PD (CFPD) – This is an old technique that has regained popularity in the management of patients with AKI. CFPD utilizes two accesses, one for inflow and the other for outflow of dialysate. A large intraperitoneal volume of dialysate is replenished in a continuous manner (single-pass CFPD) or recycled by using an external machine to regenerate sterile dialysate. This technique allows for increased dialysate flow rates of up to 300 mL/min and urea clearances in the range of 30 to 50 mL/min. Several catheter designs are now available for CFPD to facilitate adequate mixing of intraperitoneal dialysate [35-39].

Choosing among modalities — For patients with AKI with severe metabolic disturbances, we prefer to initiate dialysis with HVPD. For patients with AKI who have predominant pulmonary edema, we prefer either HVPD or CEPD. However, the modality chosen depends upon availability of resources (eg, cycler, nursing support) and the clinical status of the patient. Manual methods require constant nursing activity and monitoring, whereas the cycler helps partially automate the process with a minimal need for nursing supervision. The cycler has the added advantage of a reduced potential for breaks in sterile technique compared with multiple manual exchanges. However, there are no published studies showing superior outcomes with automated PD compared with manual exchanges in AKI.

PD PRESCRIPTION FOR AKI — The prescription for acute PD is typically reassessed every 24 hours to account for clinical changes and evolving goals in the setting of AKI [40].

Components of the prescription — The components of the dialysis prescription are as follows:

●Dialysate solution – Various solutions are available and are described above. (See 'Dialysate solution' above.)

●Exchange volume – The exchange volume is the amount of dialysis solution instilled into the peritoneal cavity during an exchange. Factors affecting this volume include the peritoneal cavity size, the presence of pulmonary disease and/or hernia(s), fresh abdominal incisions, the degree of uremic toxicity, and the desire to limit leakage of dialysate. The average exchange volume is 30 mL/kg. The exchange volume can be lowered to 20 mL/kg among patients who experience dialysate leakage or severe gastroesophageal reflux disease. In general, patients should be initiated with smaller volumes that can be progressively increased as tolerated.

●Inflow time – Inflow time is the time required to instill the dialysate into the peritoneal cavity, a process usually aided by gravity. Inflow usually takes approximately 10 to 15 minutes (200 mL/min) [3,11]. Factors that determine the inflow time include:

•The dialysate volume.

•The degree of elevation of the dialysate bag above the patient's abdomen.

•The presence of inflow resistance resulting from kinking of the peritoneal catheter or from reduced bowel motility.

To maximize the efficiency of dialysis, it is imperative to keep the inflow time to a minimum.

●Dwell time – The dwell time is the period during which the full exchange volume remains in the peritoneal cavity or the time between the end of inflow to the beginning of the drain period. Dwell times can vary depending upon the chosen PD modality. (See 'Selecting PD modalities for AKI' above.)

The dwell time for standard acute PD is approximately 30 to 90 minutes. During this time, the gradients favoring urea and fluid removal are most favorable [11]. A dwell time <30 minutes is usually not adequate [15,41].

Among patients on acute continuous equilibrated peritoneal dialysis (CEPD), the approximate dwell time is three to six hours [11,29]. However, dwell times can be shortened and number of exchanges increased, if desired.

We generally do not initiate PD among patients with known peritonitis. However, in situations where PD needs to be continued for patients who were on PD before diagnosis of peritonitis or when other dialysis modalities are unavailable, we shorten the dwell time. This is because the glucose gradient dissipates more quickly across the more permeable peritoneum in the setting of peritonitis.

●Outflow time – Outflow time is the time required to drain the effluent dialysate from the peritoneal cavity. The outflow of the dialysate is aided by gravity and usually takes approximately 20 to 30 minutes (100 mL/min) [3,11]. Some of the major determinants of the outflow time include:

•Volume of the dialysate effluent to be drained.

•Outflow resistance, which results from kinks in the catheter, decreased bowel motility, and fibrin or blood clots in the dialysate. Bowel evacuation often shortens drainage time.

•The height difference between the patient and the drainage bag.

As with the inflow time, it is important to keep the outflow time to a minimum. This can be done by adjusting the height of the drainage bag.

●Number of exchanges – The number of exchanges is usually determined by the amount of fluid and solute removal required in a particular patient. Although it may vary, the usual number of exchanges is approximately four to six per day with CEPD and 24 per day with high-volume PD (HVPD) [22,29].

Initial prescription — During the initial 48 hours, the duration of the cycle needs to be determined based upon the clinical circumstances. Short cycle times (every one to two hours) and a high frequency of exchanges may be necessary in the first 24 to 48 hours to correct hyperkalemia, fluid overload, and/or metabolic acidosis.

AKI with pulmonary edema — Among patients with AKI who have pulmonary edema, we optimize ultrafiltration using PD by gradually altering the dextrose concentration of the dialysate and the cycle length, as tolerated.

Ultrafiltration can be increased by raising the concentration of dextrose and/or shortening the cycle duration. We typically initiate PD with a 2.5 percent dextrose solution and modify the prescription (to a higher or lower dextrose concentration) depending upon the evolving ultrafiltration goals in the setting of AKI. Among patients who are hemodynamically unstable, we use the 1.5 percent dextrose solution with frequent exchanges to slow down ultrafiltration. Even with 1.5 percent dextrose solutions, frequent exchanges, such as hourly, can lead to ultrafiltration rates of 100 mL/hour.

Dialysis solutions with higher dextrose concentration can be substituted based upon the ultrafiltration requirements and the patient's hemodynamic parameters. With a standard regimen, such as a 2-liter exchange volume and one-hour dwell time, the following approximate amounts of fluid can be removed over a 24-hour period:

●2.5 liters with 1.5 percent dextrose

●4.5 liters with 2.5 percent dextrose

●8.5 liters with 4.25 percent dextrose

One practical way to achieve adequate fluid removal is to alternate by mixing and matching low- and high-dextrose concentration solutions. Among patients receiving manual PD, this entails manually alternating bags of different dextrose concentrations, whereas for patients on automated PD, bags of varying dextrose concentrations get mixed when sequenced one after another.

AKI with hyperkalemia or uremic symptoms — Among patients who have severe hyperkalemia, metabolic acidosis, or uremic symptoms, short and frequent cycles are usually necessary to achieve metabolic control. We prefer HVPD or tidal PD (TPD) as modalities of choice in such situations.

We typically initiate PD with either a 1.5 or 2.5 percent dextrose solution, at the rate of one cycle per hour for the first 24 to 48 hours using exchange volume ranges of 20 to 40 mL/kg for a total dialysate volume of 32 to 48 liters.

As an example, in a 60 kg woman with anuric AKI, a typical initial prescription would be:

●Session duration = 24 hours

●Number of cycles = 16

●Dwell time = 1 hour

●Inflow volume = 2 L (33 mL/kg)

●Total dialysate = 32.4 L

●Inflow time = 10 min

●Outflow time = 20 min

We then modify the prescription (to a higher or lower total volume, exchange volume, and dwell time) depending upon the evolving metabolic goals in the setting of AKI.

These prescription principles were successfully applied to patients with coronavirus disease 2019 (COVID-19)-associated AKI who were managed with acute PD during the worst of the early phases of the pandemic, when AKI, hypercatabolism, respiratory failure, and cytokine storm dominated the clinical picture [42,43]. (See "COVID-19: Issues related to acute kidney injury, glomerular disease, and hypertension", section on 'AKI requiring dialysis'.)

Subsequent prescription — Patients who have improvement in their hyperkalemia, metabolic acidosis, uremic symptoms, and/or hypervolemia can be transitioned to a less intense PD prescription until there is sufficient return of native kidney function.

Subsequent prescription for all patients — We alter the prescription by increasing the cycle length to four to six hours to match the metabolic needs of the patient. Among patients who are euvolemic, the volume status can generally be maintained with a 1.5 percent dextrose dialysate. As the native kidney function begins to return with associated improvement in metabolic and volume control, we gradually taper the number of cycles until the native kidney function recovers enough for the patient to be off PD.

As an example, in a 60 kg woman with anuric AKI who has had initial improvement in volume and metabolic control, a typical prescription would be:

●Session duration = 24 hours

●Number of cycles = 6

●Dwell time = 3.5 hours

●Inflow volume = 2 L (33 mL/kg)

●Total dialysate = 12 L

●Inflow time = 10 min

●Outflow time = 20 min

Dialysate additives among selected patients — Drugs can be added to the dialysis solution to treat specific conditions [5]. It is imperative to follow sterile technique when adding additives into dialysate solutions. Some of the commonly used dialysate additives are heparin, insulin, and potassium.

Patients with fibrin or clots in dialysate — We add unfractionated heparin at a dose of 200 to 500 units/L of dialysate when clots or strands of fibrin are visible in the drained dialysate. This is to prevent obstruction of the peritoneal catheter with a fibrin clot [26].

Heparin is generally only beneficial when added prophylactically. Patients who have an established outflow obstruction are unlikely to benefit from heparin. Such patients should have fibrinolytic agents (eg, 6 mg of 1 mg/mL solution of alteplase) instilled in the peritoneal catheter instead. Neither heparin nor fibrinolytic agents are absorbed through the peritoneum, and, therefore, neither result in systemic anticoagulation.

Patients who have diabetes — Patients who have diabetes may have a significant impairment in their blood sugar control from the large glucose load contained in hypertonic dextrose-based dialysates. We manage such blood sugar surges by adding insulin to the dialysate. We also initiate blood sugar monitoring every six hours to guide any modifications in insulin dosing. We typically instill the following starting doses of regular insulin in the dialysate [26]:

●4 to 5 units/L to a 1.5 percent dextrose bag

●5 to 7 units/L to a 2.5 percent dextrose bag

●7 to 10 units/L to a 4.5 percent dextrose bag

Patients who have hypokalemia — Patients who have hypokalemia should have potassium chloride added to their dialysate. In addition, potassium chloride should be prophylactically added to each dialysate bag for patients with serum potassium levels below 4 mmol/L (4 mEq/L).

Acute PD can result in hypokalemia due to substantial losses of potassium with each exchange (approximately two-fold the serum potassium concentration with each 2 L exchange). Usually, there is no potassium contained in standard dialysate solutions. Thus, supplementation is needed for patients who develop or are at risk for hypokalemia (ie, patients with a serum potassium below 4 mmol/L or 4 mEq/L).

Untreated hypokalemia can result in severe depletion of total body potassium and cardiovascular complications, such as arrhythmias. In addition, hypokalemia has been associated with an increased incidence of peritonitis in the chronic PD population [44,45]. This is thought to be from reduced gut motility due to hypokalemia, potentially leading to bacterial overgrowth and transmural migration of enteric organisms.

Role of Kt/V — Some of our contributors modify the prescription using Kt/V in addition to clinical and laboratory assessment, while other contributors rely on the clinical and laboratory assessment alone. When Kt/V is used, we agree with the International Society of Peritoneal Dialysis (ISPD) guidelines that state a weekly Kt/V goal of 3.5, when resources permit [5]. However, a lower Kt/V of 2.1 is sufficient for many patients. Thus, we aim for a Kt/V urea goal of 3.5 in the first 48 hours, and 2.1 thereafter, provided that there is improvement in metabolic control [22,46,47].

COMPLICATIONS OF PD FOR AKI — Acute PD is associated with complications, some of which are serious and potentially life threatening [6,48,49]. Compared with chronic PD, some complications, such as peritonitis or leakage, may be more common, and others can be more severe, such as increased intra-abdominal pressure and metabolic complications. These important complications are discussed below:

●Peritonitis – Peritonitis has been reported among approximately 12 percent of patients who underwent PD for AKI [4]. The incidence of peritonitis can be decreased by maintaining sterile precautions during the placement of acute PD catheters and by maintaining aseptic precautions during exchanges. Leaking dialysate predisposes to peritonitis. We agree with the International Society for Peritoneal Dialysis (ISPD) guidelines that advise daily surveillance of effluent leukocyte counts [5]. (See "Clinical manifestations and diagnosis of peritonitis in peritoneal dialysis".)

●Increased risk of respiratory failure – Indwelling peritoneal fluid can increase intra-abdominal pressure. This increase in intra-abdominal pressure may theoretically decrease pulmonary compliance and ventilation, thereby worsening respiratory failure, especially among patients who are mechanically ventilated [50,51]. However, evidence confirming this complication of PD is conflicting [16,17].

●Protein losses – Protein losses occur in the dialysate, often exceeding 5 g/day and up to 12 g/day. However, these protein losses can be as high as 48 g during episodes of peritonitis [6,9,52]. This is exacerbated by tidal peritoneal dialysis (TPD) [14], aggressive ultrafiltration, and infection. Negative protein balance is associated with increased mortality [8]. We advise patients to consume adequate protein, aiming for approximately 1.2 g/kg of protein per 24 hours.

●Hypernatremia – Hypernatremia can result from disproportionate loss of free water in the PD fluid in patients who require repeated use of hypertonic exchanges (ie, 4.25 percent dextrose).

Typically, the glucose-generated tonicity of the dialysate activates the aquaporin-1 channels in peritoneal capillaries. This activation allows free water to move down these channels into the peritoneal cavity. Such movement of water creates a diffusion gradient for sodium to move from blood to the dialysate via small intercellular pores. However, when the exchanges are rapid and the dwell time is short, the time for sodium equilibration is inadequate. This leads to excess sodium relative to free water remaining in the circulation, thereby leading to hypernatremia. Hypernatremia can be corrected either by increasing the dwell time and/or using a less hypertonic dialysate (ie, with a lower dextrose concentration).

Additional discussion of complications is presented in other topics:

●Peritonitis and exit-site infections (see "Microbiology and therapy of peritonitis in peritoneal dialysis")

●Peritonitis and exit-site infections (see "Clinical manifestations and diagnosis of peritonitis in peritoneal dialysis")

●Gastroesophageal reflux disease, pleural effusion, pleuro-peritoneal leaks, hemoperitoneum, pain on dialysate infusion, electrolyte abnormalities, and back pain (see "Noninfectious complications of continuous peritoneal dialysis")

●Inadequate solute clearance (see "Inadequate solute clearance in peritoneal dialysis")

●Abdominal hernias (see "Abdominal wall hernia and dialysate leak in peritoneal dialysis patients")

●Outflow failure, pericatheter leakage, catheter cuff excursion, intestinal perforation, and bleeding (see "Noninfectious complications of peritoneal dialysis catheters")

OUTCOMES WITH PD FOR AKI — Interest in PD for AKI is increasing and safety of PD for AKI is improving [53]. PD can be successfully used to treat AKI, and has efficacy and survival comparable with hemodialysis (HD) and continuous kidney replacement therapy (CKRT) [22,46,54]. In a 2017 Cochrane review of six trials and 484 patients with AKI, patients who were treated with PD were compared with patients treated with extracorporeal therapies (HD, extended daily HD, or CKRT) [54]. There were no differences in all-cause mortality, kidney function recovery, or infectious complications.

In a subsequent trial, 125 critically ill patients with AKI were randomly assigned to high-volume tidal PD or CKRT [18]. At 28 days, patients treated with PD had a higher rate of survival (70 versus 47 percent), a higher rate of kidney function recovery (60 versus 37 percent), a lower rate of infectious complications (10 versus 18 percent), and a shorter median length of intensive care unit stay (9 versus 19 days).

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Acute kidney injury in adults".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topic (see "Patient education: Acute kidney injury (The Basics)")

SUMMARY AND RECOMMENDATIONS

●Advantages of PD for AKI – Compared with other available modalities, peritoneal dialysis (PD) has several advantages as a kidney replacement therapy (KRT) for patients with acute kidney injury (AKI). These include logistical ease of setting up PD, superior hemodynamic tolerance, lower risk of dialysis disequilibrium syndrome, lack of a need for anticoagulation, and hyperalimentation among malnourished patients. In addition, PD is used for AKI when hemodialysis (HD) and continuous KRT are not available. (See 'Advantages of PD for AKI' above.)

●Dialysis access – Dialysis access for PD depends upon local availability of resources. We prefer to place a flexible double-cuff catheter. Other catheter options include flexible single-cuff, semi-rigid, rigid, or improvised catheters (eg, nasogastric tube, intercostal drainage catheters). A PD catheter can be inserted using the modified-Seldinger technique, laparoscopy, or laparotomy depending upon local procedural expertise (table 1). (See 'Dialysis access' above.)

●Dialysate solution – Peritoneal dialysates used in the setting of AKI are similar to those that are used in the setting of end-stage kidney disease (ESKD). Ideally, commercially prepared dextrose-based solutions should be used. However, in resource-limited settings, cost-effective and improvised options may need to be formulated. (See 'Dialysate solution' above.)

●Selecting PD modalities for AKI – Acute PD can be performed either intermittently or continuously, depending upon the amount of fluid and solute removal desired. It can be performed either manually or using an automated cycler. (See 'Selecting PD modalities for AKI' above.)

•Available modalities include high-volume PD (HVPD), continuous equilibrated PD (CEPD), acute intermittent PD, tidal PD, and continuous flow PD. (See 'Available modalities' above.)

•For patients with AKI with severe metabolic disturbances, we prefer to initiate dialysis with HVPD. For patients with AKI who have predominant pulmonary edema, we prefer either HVPD or CEPD. However, the modality chosen depends upon availability of resources (eg, cycler, nursing support) and the clinical status of the patient. (See 'Choosing among modalities' above.)

●PD prescription for AKI – The prescription for acute PD is typically reassessed every 24 hours to account for clinical changes and evolving goals in the setting of AKI. The prescription includes type of dialysate solution, exchange volume, inflow and outflow times, dwell time, and number of exchanges. (See 'PD prescription for AKI' above.)

•Our initial prescription generally involves short cycle times (every one to two hours). A high frequency of exchanges may be necessary in the first 24 to 48 hours to correct hyperkalemia, fluid overload, and/or metabolic acidosis. (See 'Initial prescription' above.)

•Subsequently (after initial improvement), we alter the prescription by increasing the cycle length to four to six hours to match the metabolic needs of the patient. Among patients who are euvolemic, the volume status can generally be maintained with a 1.5 percent dextrose dialysate. Certain dialysate additives, such as heparin for prevention of catheter clotting, insulin for treatment of hyperglycemia, and potassium supplementation for patients who are hypokalemic, can be used, when indicated. (See 'Subsequent prescription' above.)

●Complications – A majority of complications of PD for AKI are similar to those seen among patients who are on PD for ESKD. However, certain complications such as peritonitis, increased risk of respiratory failure, hypernatremia, and increased protein losses may be more prevalent in the acute PD population. (See 'Complications of PD for AKI' above.)

●Outcomes – There is no difference in the rates of all-cause mortality, kidney function recovery, or infectious complications among AKI patients treated with PD compared with any other modality. (See 'Outcomes with PD for AKI' above.)