Usage of Peritoneal Dialysis in Infants Following Correction of Congenital Heart Defects

Yakimishen O., Boyko S., Malysheva T., Spisarenko S., Truba Y., Lazoryshynets V.

National Amosov Institute of Cardiovascular Surgery, Kyiv, Ukraine

Abstract. Children with congenital heart disease have an increased risk of acute kidney injury (AKI) after cardiac surgery.

Conditions preceding this complication include: acute inflammatory reaction to artificial blood circulation and postoperative hemodynamic instability, ischemia or reperfusion injury, circulating mediators of inflammation and myoglobin, postoperative hemolysis, attachment of the infectious agent, congestive heart failure, and renal failure. One of the methods for resolving this condition is peritoneal dialysis (PD), especially relevant for newborns and infants.

Objective. To analyze our experience of using peritoneal dialysis in children under 1 year with acute kidney injury after cardiac surgery and to identify the factors causing this complication.

Materials and methods. The retrospective analysis of efficacy of peritoneal dialysis and risk factors for AKI in children under 1 year of age, following cardiac surgery in National Amosov Institute of Cardiovascular Surgery National of Ukraine period from 2014–2018 years was performed. During this period, 620 children underwent surgical interventions, the mean age was 6±5.4 months, the mean weight was 6±4.2 kg.

Results. In the postoperative period, 112 (18%) patients developed acute kidney injury, and of those peritoneal dialysis was used in 57 (50.2%). The indications for PD initiation included oliguria (n=31), anuria (n=18), metabolic acidosis (n=8). The average time between cardiac surgery and AKI was 4±16.8 hours, and 12±6.5 hours between AKI and PD initiation. PD usage lasted 8±5.8 days. The following complications were reported: peritonitis in five patients, and PD catheter malfunction in 11 patients. Hospital mortality associated with PD was 42% (n=24). Patients with PD had a lower weight (p=0.004) and had longer artificial circulation (p=0.004), inotropic support (p=0.002), and mechanical ventilation (p=0.003). However, in regression analysis, only the time of artificial circulation (odds ratio: 1.021; 95% confidence interval: 0.998–1.027; p=0.032) remained predictive.

Conclusion. Peritoneal dialysis is an effective osmotic ultrafiltration for the children under 1 year with acute kidney injury after cardiac surgery. Only the time of artificial circulation is predictive.

Keywords: congenital heart disease, artificial circulation, acute kidney injury, peritoneal dialysis.

Children who underwent surgery for complex congenital heart disease (CHD) are especially predisposed to acute kidney injury (AKI). AKI is an early complication, and general information about the treatment of postoperative AKI includes the correction or elimination of the damage factor and maintaining the water balance. However, in case of volume overload as well as oliguria or anuria renal replacement therapy should be considered, in particular peritoneal dialysis (PD), which is considered to be the best technique for children in the first year of life for a long time due to lack of vascular access, simplicity and low cost [4]. The reported level of AKI after cardiac surgery ranges from 1 to 18% [1, 2], largely dependent on the criteria used to determine the condition, and the associated mortality rate is high (21-70%) [3].

The purpose of the study is to analyse our experience of using peritoneal dialysis in children under 1 year with acute kidney injury after cardiac surgery and to identify the factors causing AKI.

Materials and methods. In 2014–2018, 620 surgical interventions with CPB in children of the first year of life with CHD were conducted at National Amosov Institute of Cardiovascular Surgery of the National Medical Academy of Ukraine. The retrospective study included 112 (18%) children with CHD of this group of patients who developed acute renal injury in the postoperative period, including 57 (50.2%) children with peritoneal dialysis used as replacement therapy. Demographic and clinical data included age, weight, type of congenital heart defect, details of surgery, risk, and evaluation (RACHS-1) [5]. The findings represented postoperative kidney function, the time of diagnosing AKI and initiating PD after surgery, artificial circulation time, type and duration of inotropic support. The Paediatric Risk of Mortality (PRISM II) score was also calculated [6], which uses data from the first 24 hours after admission to the intensive care unit to predict patient outcomes.

Acute kidney injury was diagnosed using the AKIN criteria [7], which is defined as the percentage increase in serum creatinine by 50% or more (1.5 times baseline) within 48 hours or a decrease in diuresis of less than 0.5 ml/kg/hour for 6 hours or more.

Dialysis catheters were surgically delivered under general or local anaesthesia. In some patients, the PD catheter was inserted during cardiac surgery due to a decrease in diuresis during surgery or predicted development of AKI after surgery. PD catheters were ribby to reduce the risk of mechanical dysfunction. The exchange volume of dialysis was 10 ml/kg in all patients, the dialysis rate per hour varied according to clinical and laboratory parameters.

Peritoneal dialysis is usually started with isotonic dialysate, which is a balanced salt solution with sodium level of 140 mmol/l (also containing calcium, magnesium, chloride, and lactate) and glucose of various concentrations (1.36%, 2.27%, 3.8% ). The solution of the lowest osmolarity was most often prescribed. More hypertonic solutions were used to treat volume overload. Additives (such as bicarbonate, potassium chloride, heparin or antibiotics) were added to the solution as needed.

Given the small sample size, logistic regression analysis to identify factors suggesting further PD necessity and mortality after cardiac surgery was performed using the entire cohort of patients who developed AKI (n=112). We included preoperative and intraoperative variables (age, weight, RACHS-1 score ≥4, artificial circulation time, and urine output) in the first model to identify factors that might suggest PD. Subsequently, in the second model, we included preoperative, intraoperative, and postoperative variables (age, weight, RACHS-1 score ≥4, artificial blood flow, duration of inotropic support, duration of mechanical ventilation, and PD treatment (yes or no)) to find independent predictors of mortality. In both models, the coefficient of probability was defined as p<0.05.

Results and discussion. During 2014–2018, 620 surgical interventions with artificial circulation in children of the first year of life with CHD were performed at National Amosov Institute of Cardiovascular Surgery of the National Medical Academy of Ukraine. AKI incidence according to AKIN criteria was 18% (112 patients), renal replacement therapy in the form of PD was used in 57 patients (9.2%). The mean age in the PD group was 6±5.4 months and the average weight was 6±4.2 kg.

In 50 patients (87.7%) who underwent PD, the RACHS-1 score was 4 or higher (according to type of congenital heart defect and type of cardiac surgery). The average PRISM II score was 19.3±6.

In 35 patients, AKI occurred within the first 12–24 hours after surgery. The average time between surgery and diagnosis of AKI was 4±16.8 hours (0–48 hours), and 12±6.5 hours between AKI diagnosis and PD initiation (0–72 years). In 36 patients (63%), PD started less than 24 hours after surgery; and 9 patients (15.8%) had a PD catheter installed during cardiac surgery. The indications prior to dialysis were oliguria (31 patients), anuria (18 patients) and metabolic acidosis (8 patients). The average duration of dialysis was 8±5.8 days (1–14 days).

The volume of dialysate was 10 ml/kg and the residence time increased from 15 to 60 minutes. 32 patients (56%) required ultrafiltration optimization and volume overload correction.

All patients requiring PD received inotropic support after cardiac surgery with two agents. Three inotropic agents were required in 29 patients (52%). The average duration of inotropic administration was 124±40.8 hours, the mean artificial circulation time was 126.6±78 minutes.

Complications associated with PD were reported in 16 patients: 5 patients (31.25%) developed peritonitis, and 11 (68.75%) had mechanical dysfunction of the PD catheter. Episodes of peritonitis were diagnosed 6–9 days after initiation of PD treatment, which was confirmed by the presence of leukocytes in dialysate. However, there were no systemic septic complications, and in no case did the infection result in PD termination. Episodes of peritonitis were treated with the introduction of antibiotics with the addition of antiseptics, while PD remained; subsequently, the transition to intravenous therapy was completed to finish the antimicrobial course.

The hospital mortality rate in patients receiving PD was 42% (n=24) and was explained by various complications – heart failure, infectious-toxic shock, multiple organ failure syndrome, disseminated intracranial coagulation syndrome. Renal function was fully restored in surviving patients.

In the cohort of patients with AKI, the patients who required PD were statistically different: they had less weight, but longer artificial blood flow, use of inotropic agents, duration of mechanical ventilation and hospital stay (Table 1). This group was also characterised by a decrease in urine output immediately after surgery, but no differences in the RACHS-1 score were observed. The deceased patients who received PD also had more time for artificial circulation and the use of inotropic support. Hospital mortality in 30 patients (p=0.456) who received PD did not differ in RACHS-1 scores (Table 1).

Table 1

Clinical criteria for the examination of patients

Regression analysis showed that longer artificial circulation was a major predictor of PD after cardiac surgery (Table 2).

Table 2

Analysis of the predictors for peritoneal dialysis in patients (n=112) with AKI

However, when considering the prognosis, the duration of artificial circulation, the time of ventilation, and the use of inotropic support were associated with mortality (Table 3).

Table 3

Analysis of hospital mortality in patients (n=112) with AKI

Children who underwent surgery for CHD are particularly predisposed to acute kidney injury. Acute kidney injury is an early complication after surgery. We used the AKIN criteria for our patients: an increase in serum creatinine of 50% or more (1.5 times baseline) for 48 hours or a decrease in urine level of less than 0.5 ml/kg per hour for 6 hours or more. In young children, PD may have some benefits as it eliminates the need for a vascular catheter and is well tolerated by hemodynamically unstable patients. The percentage of patients with AKI who received PD was 9.2% (the range reported in the literature [8]).

In some complex operations, taking into account this possible complication, the dialysis catheter was installed in the operating room, and PD began in the first hours after surgery. Literature data confirm that an earlier onset of dialysis is associated with a lower mortality and restoration of the filtration renal function [4]. Our patients who received PD treatment and died tended to have a longer time between the diagnosis of AKI and the initiation of PD. This indicates that rapid correction of metabolic disorders and hypervolemia is associated with a better prognosis in severely ill children.

As soon as correction of low ejection syndrome is achieved, rapid improvement of renal function is usually the rule. In the study group, renal function recovery in surviving patients was 100%.

PD is usually a safe method. The incidence of complications observed in children with PD after cardiac surgery was 28% (n=16). CHD complexity and PD duration were among the factors associated with an increased risk of PD problems [1].

The overall mortality rates after PD, both in the hospital (42%, n=24) and in the long term, were comparable to those reported in the literature [4]. In this situation, mortality is more associated with the underlying primary heart disease than with other diseases. Even if AKI presence may have complications, a long hospital stay in this situation is a worse prognosis. The relation between AKI and mortality should take into account the overall risk of death due to congenital heart disease. In patients with low risk, the correlation of AKI/mortality was higher, and in those with a higher degree of correlation, it was low, since the death was explained not only by AKI but also by heart failure [1]. Our study showed that longer artificial circulation was a prognostic factor for the continued need for PD, although the severity of CHD does not correlate with the likelihood of renal replacement therapy or mortality.

It is expected that AKI rate after surgery for congenital heart defects will increase. Early diagnosis (including prenatal) and its accuracy lead to more complex surgery at an early age. Thus, attention to improving PD techniques and identifying factors associated with deterioration in prognosis are crucial for better treatment of such patients.

Conclusions. Peritoneal dialysis is an effective osmotic ultrafiltration for children with congenital heart diseases under 1 year with acute kidney injury after cardiac surgery, and the time of artificial circulation is a major predictor of the need for renal replacement therapy.

References

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Published: March 2019