This was a prospective, double-blind, parallel assignment, investigator-initiated randomized controlled trial conducted from August 2017 to December 2018 in the Pediatric Emergency and Intensive Care Units of a large tertiary care, teaching and referral hospital in India. All consecutive children > 1 month to < 12 years who presented to the pediatric emergency room with DKA as defined by the International Society of Pediatric and Adolescent Diabetes (ISPAD-2014) were enrolled into the study [20]. Children with symptomatic cerebral edema (GCS < 8 at presentation) or known chronic kidney disease or liver disease or who had received pre-referral fluids and/or insulin at the time of hospital presentation were excluded. The severity of DKA was classified as mild if pH was between 7.2 and 7.3, moderate if pH was between 7.1 and 7.2, and severe if pH was < 7.1.

Sample size estimation

Sample size was calculated with AKI as a composite outcome using multivariate Cox Proportional Hazard Analysis. A total of 60 subjects (nearly 30 in each group) were estimated, expecting that 30 out of them meet one or other composite AKI criteria. With an alpha error of 5% and power of 80%, we assumed that the hazards of AKI in Plasma-Lyte will be 0.3 times lower than saline and the hazard ratio is constant throughout the study.

Data was analyzed as per intention-to-treat principle. Unadjusted chi-square test was used to analyze the differences in primary outcome. Absolute and relative risks with 95% confidence intervals were calculated. Survival analysis for time to resolution of AKI and DKA were compared with log-rank test. A Cox proportional hazards regression model was used to evaluate the influence of potential confounders on outcome as age, new onset DKA, and severity of DKA. Quantitative variables with normal and non-normal distribution were expressed as mean (with standard deviation) or median (with inter-quartile range) respectively. Unpaired Student’s t test or Wilcoxon rank-sum test was used for intergroup comparisons. General linear model repeated measure ANCOVA was used to compare the trends of continuous variables over time. A P value (two-tailed) < 0.05 was taken as significant. IBM SPSS Version 21 and R software were used for data analysis.

Randomization and blinding

The randomization scheme number was generated by a person not involved in the study using a web-based program for 1:1 allocation (http://www.randomization.com). Patients were randomized into 2 groups 0.9% saline and Plasma-Lyte-A by unstratified, block randomization with variable block sizes. The fluids (Plasma-Lyte-A and 0.9% saline) were purchased from Company Baxter (India) Pvt. Ltd., and the company had no involvement in the study protocol, data collection, or analysis. Both study fluids (Additional file 1: Table S1) were packed in identical 500-ml bags, covered with two opaque plastic silver foil wraps by a nurse not involved in study and sequentially numbered as per allocation sequence. The allocation was known only to one member of the administrative staff not involved in the study. The patient assignment was sequential. Patients and treating physicians were blinded to the treatment. Once patient’s eligibility for enrolment was determined, a study nurse blinded to the fluids was ordered to administer the crystalloid solution as per the randomization scheme.

Treatment protocol and monitoring

Parents or legal guardians of children who satisfied the eligibility criteria were approached by the investigator for a possible enrolment in the emergency department. Parents were free not to participate or to withdraw from the study at any point of time. Written informed consent was obtained from the parents or next of kin prior to enrolment. All children, irrespective of their enrolment in the study, received standard care as per the unit’s existing protocol (Additional file 2: Figure S1). A basic data form including screening details, demographic data, precipitating factors, presenting complaints, pre-referral treatment, nutritional status, and physical, biochemical and hemodynamic findings were completed.

The enrolled children were managed according to the standard clinical protocol for DKA followed in our unit (Additional file 2: Figure S1). Urinary NGAL estimation was done for the purpose of trial. Eligible children who presented in shock [perfusion abnormalities with or without hypotension (blood pressure < 5th centile for age)], received trial fluid bolus of 20 ml/kg over an hour. In those without shock, the fluid volume was calculated as a sum of deficit (65–100 ml/kg) and maintenance for the next 48 h and administered as an hourly infusion. Insulin was started at 0.05 U/kg/h in all after initial hour of fluid therapy. Neurological status was monitored hourly anticipating cerebral edema. Fluids were changed to 0.45% saline and 5% dextrose once blood glucose fell below 250 mg/dl. In case of persistently high blood glucose, the clinician went through a checklist that included patency of intravenous cannula, insulin preparation and its shelf life, and appropriateness of dilution before increasing insulin to 0.1 U/kg/h.

Implementation of study protocol

The protocol was discussed in multiple sessions with the resident doctors and nurses posted in PICU and Emergency units on the first day of every month throughout the duration of the study. The investigator visited the Emergency and PICU at least twice a day and as and when needed to ensure strict implementation of protocol. Phone number of the investigator was made available in both the units. Posters of protocol design were displayed on the notice boards of the Emergency and PICU. Weekly checks on protocol adherence were carried out by the co-investigators.

Clinical data (respiratory rate, pulse, capillary refill, blood pressure, hydration status, fluid intake, urine output) were continuously recorded, and the values were entered in a pre-designed monitoring sheet. Blood glucose (capillary or venous) was checked every hour and blood gas every 4 h. Urea, creatinine, and electrolytes were measured every 4–8 hourly. We used the enzymatic method of creatinine estimation to prevent interference with non-creatinine products.

For KDIGO staging, if pre-admission creatinine values were available, either the single value or the least value (in case of multiple values) during the previous 3 months was taken as baseline value. If baseline creatinine was unavailable, then a GFR of 127 ml/min and 103 ml/min were assumed for children above 1 year and below 1 year respectively to calculate creatinine using Schwartz formula (Additional file 1: Appendix).

The need for RRT was assessed daily. In addition to renal failure-related data points, the duration of mechanical ventilation (MV), length of ICU and hospital stays from time of study enrolment, and in-hospital mortality were recorded.

NGAL estimation

The concentration of NGAL was estimated with the commercial HumanLipocalin-2/ NGAL ELISA kit (BioVendor Laboratory Medicina, Czech Republic) in a sandwich enzyme immunoassay as per manufacturer instructions. Limit of NGAL detection was 0.02 ng/ml with inter-assay coefficient of variance (CV) of 7.8% and intra-assay CV of 9.7–9.8%.

Study outcomes

The primary outcome was incidence of new onset or progressive AKI defined as ONE of the following composite outcomes: change in serum creatinine or urine output as per KDIGO classification OR, change in GFR as calculated using Schwartz formula OR, and change in urinary NGAL. The individual outcomes were divided into quartiles, and the worst quartile was used to define AKI. The standard definitions of individual outcomes are provided in Additional file 1: Appendix. Analysis was done separately for absolute levels and their worst quartiles. The secondary outcomes were rate of resolution of AKI, time to resolution of DKA (pH > 7.3, bicarbonate > 15 mEq/L and normal sensorium), change in chloride, pH and bicarbonate levels (baseline, 24 h), proportion of in-hospital all-cause mortality, proportion of children requiring renal replacement therapy (RRT), length of ICU and hospital stay.

Follow-up

Patients were followed up till discharge from PICU or ward or death, whichever was earlier. Post discharge, the children were assessed in the PICU and diabetic follow-up clinics. Patients failing to attend day 28 follow-up were contacted through telephone to ascertain the survival status. Renal function tests were carried out wherever needed. A data safety monitoring board supervised the conduct of the trial (Additional file 1: Appendix).