Acute renal failure (ARF) is a syndrome defined by sudden impairment of filtration and an increase of nitrogenated compounds in blood with or without decreased urinary output. In Mexico, its prevalence is 79.7 per cent in pregnant women with high-risk factors,1 and 75 per cent in pre-eclamptic patients hospitalized in intensive care units (ICU).2

Critically ill obstetric patients are especially susceptible to develop ARF. Both the clinical manifestations and the complications are related to renal failure and fetoplacental repercussion.3 Early diagnosis and timely treatment solve the problem in most patients except for when severity is extreme which is when admission in the ICU is recommended.4 When required, early hemodialysis to reduce complications and serious sequelae should be initiated.5 The goal of this research was to determine the frequency and clinical progression of ARF in obstetric patients treated in the ICU of a high-specialty hospital in the City of Mexico.

1305 medical records of women admitted at the ICU of the High-Specialty Medical Unit of the Hospital of Gynecology and Obstetrics #3 of the “La Raza” National Medical Centre at the Mexican Institute of Social Security were reviewed between January 1, 2012 and June 30, 2014. Pregnant patients or patients in the puerperium phase with ARF defined as the acute impairment (<48h) of filtration based on the following Acute Kidney Injury Network (AKIN) criteria were included: (a) increase of serum creatinine (Cr) levels ≥0.3mg/dl; (b) increase of serum Cr levels ≥50 per cent (1.5 times above the basal level) and (c) uresis <0.5ml/K/h during a ≤6h period of time.6 Patients with chronic nephropathy, peritoneal dialysis, hemodialysis or carriers of renal grafts were excluded. No cases were precluded because all medical records and lab reports were complete and fully available.

The frequency of obstetric patients with ARF in relation to the total number of admissions was estimated. Three (3) measurements of the serum Cr levels and glomerular filtration rate were taken: at the moment of ICU admission, during the ARF nadir and at ICU discharge. The volume of total uresis in intensive care was studied as well. In order to estimate the glomerular filtration rate, the levels of creatinine clearance (CrCl) were estimated using the Cockroft-Gault equation (CrClml/min/1.73square meters of body surface=[(140−age)×weight (kg)/serum Cr levels (mg/dl)×72] (0.85 for being a female) (1.73 body surface [square meters]/body surface [square meters]). Clinical progression included: arterial hypotension (systolic pressure <90mmHg), surgical reinterventions, hemodialysis, outcomes, mortality and stay at the ICU. The study was authorized by the local committee of investigations (CLIS 2013-3504-29). For the statistical analysis, descriptive and inferential statistic methods (Student t test) were used. P values <0.05 were considered significant values.

Sixty-three obstetric patients with ARF were identified—some 4.82 per cent of all ICU admissions whose general data are shown in Table 1. There were no losses of patients due to lack of data in the files, or any biases for this reason. The causes for ARF were: severe preeclampsia 65.07 per cent (41 cases), eclampsia 6.34 per cent (4 cases), obstetric hemorrhage with hypovolemic shock 4.76 per cent (3 cases), sepsis 4.76 per cent (3 cases) and various diagnoses 19.07 per cent (12 cases).

ARF was diagnosed at admission in 85.71 per cent (54 cases) and in the ICU in 14.29 per cent (9 cases). Based on the AKIN criteria,6 distributions were: stage 1, 71.43 per cent (45 cases); stage 2, 19.05 per cent (12 cases) and stage 3, 9.52 per cent (6 cases). The serum Cr levels at ICU admission were 1.59±0.99mg/dl (range: 0.7–6), the ARF nadir was 1.67±0.77mg/dl (range: 1.8–6.4), and the Cr levels at ICU discharge were 1±0.61mg/dl (range: 0.4–3.9). The CrCl levels at ICU admission were 54.36±29.81 (range: 8.87–95.04), the ARF nadir was 43.55±14.13 (range: 9.95–85.73), and the CrCl levels at ICU discharge were 87.60±37.07ml/min/1.73m2 of body surface (range: 14.14–124.3) (Table 2). The mean of total volume of uresis was 1.61±1.21ml/kg/h (range: 0–5.7).

Arterial hypotension was diagnosed in 1.58 per cent (1 case), surgical reinterventions on one (1) occasion, in 11.11 per cent (7 cases), and on two (2) occasions in 4.76 per cent (3 cases), and hemodialysis in 1.58 per cent (1 case). These were the outcomes: referrals to the general ward of patients with ARF recovery in 95.26 per cent (60 cases), referrals to an infectology hospital for the management of sepsis with ARF but without hemodialysis in 1.58 per cent (1 case), referrals to the hemodialysis unit in 1.58 per cent (1 case), and mortality due to hemorrhage with ARF in 1.58 per cent (1 case). Thus, at ICU discharge, ARF progressed satisfactorily in 95.26 per cent (60 cases) and in 4.76 per cent (3 cases) the AKIN-stage 3 was maintained. Stays at the ICU were 4.30±3.72 days (range: 1–19).

In the actual investigation, the critically ill obstetric patients with ARF were 4.82 per cent – lower numbers than in previous reports in Mexico.1,2 Guerrero et al.7 studied 333 women managed in the ICU, among which 86.18 per cent (287 cases) were pregnant women whose main causes for ARF were similar: preeclampsia, eclampsia, hemorrhage, and sepsis. Findings are consistent with the studies conducted in industrialized countries3 and in developing countries like India,8 Morocco9 and Saudi Arabia.10 Arterial hypotension was scarce even though some patients underwent reinterventions one or more times. The ARF was not seriously possible because they were young women with an intact pregestational condition, and possibly because they were identified early. Following the indications of hemodialysis and pregnancy,5 the method was implemented in 1.58 per cent (1 case) only. Mortality rates were low (1.58 per cent), and similar to the 1.74 per cent reported by Guerrero et al.7 but lower than the 20 per cent reported by Prakash et al.8 and the 28.3 per cent reported by the study conducted by Bentata et al.9 and the 12 per cent reported by Aggarwal et al.10 The ARF in critically ill obstetric patients is a challenge for the multidisciplinary medical team. Intensive care can play a decisive role when trying to achieve successful results.