Role of renal resistive index in predicting AKI in Traumatic brain injury patients admitted to neuro-intensive care unit- prospective observational study

Study Protocol:

Once the patient meets the inclusion criteria, written informed consent will be obtained, and the following data will be recorded.

 Data Collection:

Patient-related details: Demographics (Age, Gender, Height, Weight), pre-existing co-morbidities with duration and medication details, presenting symptoms, diagnosis, and radiological imaging findings, details of surgical procedure (if any).

On admission to ICU: Vitals, Glasgow Coma Scale (GCS), arterial blood gases (ABG), APACHE II score, and qSOFA score will be noted

Details noted during the first 7 days of the ICU stay:

Serum creatinine & electrolytes, blood glucose levels, hemoglobin, TLC, any other abnormal laboratory values

Daily input and output

Use of hyperosmolar fluids, diuretics, ACE inhibitors, ARBs, anti- edema drugs

Details of mechanical ventilation

Sedation (if required – type and dosing)

Need of inotropes (drugs and dosage)

 POCUS examination of kidneys for renal resistive index will be done once a day on Day 1,3,5, and 7 of admission to the ICU.  A 2-5MHz array probe will be used and a longitudinal view of the kidney in B-mode will be obtained via posterolateral approach, and vessels will be localized using color doppler mode. An interlobar or arcuate artery will be identified, and using Pulse-wave Doppler, the peak systolic velocity (Vmax) and minimum diastolic velocity (Vmin) will be recorded.

Renal resistive index (RRI) will be calculated as-

(Vmax-Vmin)/Vmax.

An average of three measurements will be recorded for bilateral kidneys.

Newer USG machines, which are now available in our ICUs, provide an automated derivation of RRI where one needs to select the RRI calculation option once the renal vessels are identified and it will provide you a value of RRI via preinstalled automated formulas.

Both these methods will be used to calculate the RRI for this study.

 AKI will be defined as per Acute Kidney Injury Working Group of KDIGO (Kidney Disease: Improving Global Outcomes):

·      any rise of >0.3 mg/dl in serum creatinine within 48 hours or

·      a rise in serum creatinine 1.5 times than baseline within 7 days or

·      urine output <0.5ml/kg/hour for 6 consecutive hours

 AKI will be considered transient if serum creatinine declines by 50% or more accompanied by normal urine output for the age and weight within 3 days of onset, whereas persistent AKI will be defined by a persistent rise in serum creatinine or declining urine output for >72 hours or if patient needs renal replacement therapy.