<p>With the improving survival of sick preterm and asphyxiated term neonates, acute renal failure is encountered more often in NICUs now than before. Apart from supportive management for acute renal failure, peritoneal dialysis (PD) is required in a significant percentage of all cases.</p><sec id="sec002"><title>Why is PD preferred in comparison to other dialysis modalities in neonates?

Access is technically easier.

The clearance is superior to Continuous arteriovenous hemofiltration (CAVH).

Rapid shifts of fluid and fall of plasma osmolality are less likely than with hemodialysis (HD) (1).

In neonates, the peritoneal surface area per unit weight is approximately twice that of an adult and overall, it shows more efficiency in both urea clearance and ultrafiltration (2).

What is Peritoneal Dialysis?

Peritoneal Dialysis is a relatively safe, simple and effective procedure performed by introducing small volume of dialysate solution (usually dextrose containing salt solution) into the peritoneal cavity allowing diffusion and ultrafiltration to take place. This enables removal of accumulated waste products (i.e. urea, creatinine, potassium, etc.) and excess water through osmotic gradient from the capillaries of the peritoneum (3).

Indications for acute dialysis (<xref ref-type="bibr" rid="bib001">1</xref>–<xref ref-type="bibr" rid="bib004">4</xref>)

ARF (when conservative management has failed)

Uremic symptoms - tremors, vomiting, irritability, seizures

Hyperkalemia - Serum K > 7 meq/l

Hyponatremia - Serum Na < 125 meq/l

Metabolic acidosis - pH < 7.2 despite NaHCO₃ therapy

Fluid overload - resistant to diuretics, CCF

Hypertension

Hyperphosphatemia - Serum Phosphorous > 8.2 meq/l

Hypercatabolic states - sepsis and burns

Severe prerenal ARF due to complex cardiac malformations in preoperative or postoperative period.

Inborn errors of metabolism leading to hyperammonemia or severe organic acidemias.

Poisoning – e.g. by drugs.

Inadequate nutrition due to severe fluid restriction.

Contraindications (<xref ref-type="bibr" rid="bib001">1</xref>–<xref ref-type="bibr" rid="bib004">4</xref>)

Necrotising Enterocolitis

Abdominal defects e g. gastroschisis

Bleeding diathesis

Ventriculoperitoneal shunt or abdominal foreign body

Systemic hypoperfusion

Recent abdominal surgery (within previous 7–10 days)

Acute Dialysis catheter insertion technique In infants less than 5 kg for acute P.D a ‘manual dialysis’ technique is preferred over ‘cycling technique’ because of technical difficulty in the latter.

Type of catheters Currently in India, Vygon® polypropylene catheters (Fig. 1) are available for use to perform P.D. Neonatal catheters are 12F in size and come in a peel - pack containing 1 trocar consisting of Figure 1Vygon ® Polypropylene Catheter 12 Fr

1 stainless steel stylet

1 multi hole catheter (PP) with rounded tip

1 connecting tube with roller clamp and injection port for additional medication.

Pre-procedure care

Obtain informed consent

Check body weight and abdominal girth

Decompress stomach and catheterize the urinary bladder

Place pre-weighed diaper under the patient

Check platelet counts and coagulation profile.

Procedure for placement

Restrain the infant in supine position.

Prepare the skin of abdomen and drape to expose the insertion site.

Infuse 2% Xylocaine @ 0.5 ml/kg around the skin insertion point.

Incision - The incision site depends on preference of the physician, presence of any abdominal wall infection, presence of organomegaly and post-operative wounds. The ideal site however is a location 1/3^rd the distance from umbilicus to symphysis in the midline or a site lateral to rectus sheath at the level of umbilicus, preferably on the left side as inadvertent trauma to liver can be avoided. The lateral abdominal insertion allows for most of the catheter to lie intraperitoneally especially in premature infants and hence is preferred over midline insertion. The point of entry should be individualized for each patient by laying the catheter across the abdomen prior to insertion (2).

A 22 G angiocath is now inserted to prime the abdominal cavity with dialysis solution. Instill 20–30 ml/kg of dialysate to make catheter insertion easy. If ascites is already present then instillation of fluid may not be required.

Remove angiocath afterwards and make a small stab wound at the insertion site (don't cut muscle) and insert the trocar using gentle, steady pressure with a twisting motion. Remove the stylet and push catheter gradually towards other iliac fossa till back of pelvic is reached.

Test the patency of the entire system.

If inflow and outflow occur readily then secure the catheter with purse string suture and tape.

PD Delivery system

(Fig. 2) A peritoneal dialysis delivery system can be easily established in any nursery. The components consist of dialysis solution bag, a graduated pediatric burette for accurately measuring the amount of fluid to be administered, (all placed above the infant) and a collection system to measure the dialysate removed (placed below the level of infant). Figure 2Peritoneal Dialysis Equipment and Delivery System

N.B: The PD fluid should be warmed to 37°C to prevent cooling of the infant and to increase splanchnic blood flow (3). This can be done either with a body fluid warmer or by pre-warming the P.D fluid in a hot water bath.

PD Procedure

Following catheter insertion it is attached to the PD delivery system and dialysis is started with 10–20 ml/kg (300–600 ml/m²) per exchange.

The first few exchanges are performed without any dwell time to test catheter drainage.

Establish a cycle time. This is usually about 45-minutes and consists of a fill by gravity, dwell time of 30 minutes and drain by gravity over 10 min. Dwell time may be increased in larger stable patients and can be reduced if rapid reversal is being tried e.g. hyperkalemia. The disadvantage of long dwell time is that it leads to reduced ultrafiltration as glucose reabsorption is high and osmotic gradient decreases (2).

Establish a dialysis volume per pass. Starting volume is usually 20–30 ml/kg (3). Increase the volume by 5 ml/kg/cycle slowly with maximum volume 40ml/kg, if tolerated attained over 12–24 hrs (1). With these low volumes and short dwell times there is less compromise of respiratory site is minimized (2).

Type of dialysate fluid

Two companies presently manufacture commercially available dialysate fluid. Shree Krishna Keshav Laboratories Ltd (Aravind group) which produces a 1.7% solution (Fig. 3) and Baxter which has 1.5, 2.3 and 4.25% solutions are available. The composition of each is given below (Table 1).

Standard 1.7% Dialystae solution can usually be used but in infants with lactic acidosis, liver failure and hyperammonemia or those with no improvement of acidosis, a lactate free (bicarbonate containing) solution is required (3). Table 1

Composition of standard Peritoneal Dialysate

	1.5%	1.7%	2.3%	4.25%

Sodium (mmol/l)	134	130	134	134
Calcium (mmol/l)	1.75	1.5	1.75	1.75
Magnesium (mmol/l)	0.5	0.75	0.5	0.5
Chloride (mmol/l)	101.5	100	101.5	101.5
L-Lactate/acetate (mmol/l)	35	35	35	35
Bicarbonate (mmol/l)	–	–	–	–
Glucose-monohydrate (g/l)	15	17	23	42.5
Osmolarity (mosmol/l)	358	365	401	511
pH	7.4	7.4	7.4	7.4

Figure 3Peritoneal dialysis fluid (1.7%)

Additives to PD fluid

Heparin: 50 to 1000 units/L usually 500 units/L is added for at least 3 days to prevent fibrin formation around the catheter or until the dialysate effluent is clear (1,2).

KCl: If serum K is at or below 4 meq/L add 3 meq/L of KCl (1).

Antibiotics-Only if evidence of infection is present. Send culture and sensitivity first and then add Cephalothin 250 mg/l of dialysate + Gentamycin 8 mg/l. For fungal peritonitis, systemic therapy is needed and catheter should be removed (1).

Insulin: An IV insulin infusion may be required if dialysate dextrose concentration of 2.5% or 4.5% are used. Also once dialysis starts a lower IV dextrose concentration is desirable to prevent hyperglycemia from peritoneal glucose absorption. If hyperglycemia still persist add 1–2 U/l of regular insulin to the dialysate (3).

Duration of P.D.

The duration depends on the clinical condition and acute dialysis may continue for several days to several weeks.

Monitoring of peritoneal dialysis

Maintain hourly PD flow sheet

Volume in

Volume out

Net/hr (+/-)

Net over the course of dialysis

Intakes (enteral, parenteral)

Outputs (urine, gastric, insensible water losses, etc.)

Establish a desired fluid balance. Proceed gently if negative fluid balance is required. Reassess hydration frequently.

Measure serum glucose and potassium every 4 hrs for the 1^st 24 hrs or until stable and then twice a day. Check BUN, creatinine, Ca, phosphorous, and Mg once a day and serum electrolytes twice a day.

Obtain cell count, gram stain and culture of peritoneal effluent preferably every 24 hrs otherwise if fluid is turbid or if baby has fever or abdominal tenderness.

Infant should be weighed daily.

Effect of PD

With acute PD, correction of electrolyte abnormalities and fluid removal of 2–5 ml/kg/hr can usually be achieved permitting administration of medications and hyperalimentation (3). Some patients (severe fluid overload or positive water balance) do not respond to standard PD fluid and require increase in the glucose concentration of the fluid to increase the osmotic gradient. Still very few patients do not respond to increased concentrations because of their ability to adjust to increased concentrations very fast.

Complications of peritoneal dialysis (1) see Table 3.

Conclusion

Peritoneal dialysis remains a very important component of management of acute renal failure in neonates. If done by understanding the physiology of procedure well, it is not associated with many complications. Like any other skilled procedure, it can be perfected only by frequent practice. Table 3

Complications of peritoneal dialysis and their management

Problem	Possible Remedy

Puncture site bleeding	Apply pressure gently. Purse string suture
Leakage from exit site	Reduce dwell volume until leakage stops
Perforation of bowel, bladder	Surgical consultation
Dislodgement of catheter	Replace with a new catheter
Blood stained dialysis after Cycles	Check hematocrit frequently, Continue heparin Rule out major vessel bleeding
Extravasation of dialysate into ant. abdominal wall	Replace with a new catheter
Outflow obstruction (More than 10% of solution retained in each of several consecutive cycles)	Reposition the infant gently
	Reposition the catheter by rotation and retraction. Remove if unchanged. Replace with a new catheter
Two way obstruction	Irrigate catheter with small amount of dialysate or saline. Reposition, remove if unchanged
Hyperglycemia	Avoid high conc. of dialysate unless outflow is inadequate. Low dose insulin if required
Lactic acidosis	Use bicarbonate dialysate
Hyponatremia outflow if secondary to fluid overload	Reduce fluid intake. Aim to increase the
Hypernatremia	Increase fluid intake if secondary to excessive ultrafiltrate
Hydrothorax	Reposition the infant, head and chest above the abdomen
Hydrothorax	Decrease dwell volume
Exit site infection	Systemic antibiotics Excision of exit site PRN
Peritonitis	Several rapid flushing changes Cephalothin 250 mg/l of dialysate + Gentamycin 8 mg/L. For fungal peritonitis, systemic therapy is needed and catheter should be removed.

Peritoneal dialysis in neonates