Postoperative Acute Kidney Injury in Patients Undergoing Prolonged Neurosurgical Operations

- Postoperative acute kidney injury (AKI) is a highly prevalent and prognostically important complication in various surgical settings. Patients who developed postoperative AKI is independently associated with markedly increased morbidity, mortality1-8 and higher economic burden1.

- AKI was defined by an increase in serum creatinine (SCr) ≥ 0.3 mg/dl or by an increase in SCr ≥ 50% and/or by a decrease in urine output to 0.5 ml/kg/hour for 6 hours, in the first 48 hours after surgery.

- Patients who developed AKI had a higher total ICU costs, prolonged length of hospital and ICU stay, and longer duration of postoperative mechanical ventilation.

- AKI has been studied in different surgical procedures especially cardiac & abdominal surgeries.

- Kovacheva et al 2016 retrospective study included 1656 craniotomy patients from 1998 to 2011. The AKI used criteria was RIFLE (Risk, Injury, Failure, Loss of kidney function and End-Stage Renal Failure), they reported an incidence of 9.9% of postoperative AKI9.

- Deng et al 2017 also reported an incidence of AKI up to 13.5% in patients undergoing neurosurgical surgery within the first 7 days. It was associated with independent risk factors included intraoperative blood loss, postoperative reoperation, use of mannitol during operation, concentration of Cystatin-C; a biomarker protein detecting early kidney injury before creatinine changes and postoperative APACHE II score10.

- As the number of neurosurgical procedures has been increased worldwide and in our department as well with new types of prolonged neurosurgery e.g. Skull - Base - Major cerebrovascular beside major cranial tumor excision. It becomes a necessary to re-evaluate the incidence, factors behind AKI and outcome in such prolonged surgery.

- In 2002, The Acute Dialysis Quality Initiative (ADQI) was created with primary goal was to create a uniform, accepted definition of AKI; hence RIFLE criteria was born. RIFLE is an acronym of Risk, Injury, Failure, Loss of Kidney Function & End-Stage Kidney Failure.

- In 2004, The Acute Kidney Injury Network (AKIN) was formed. A report of the AKIN proposed the following criteria for AKI.

- The AKIN criteria differ from the RIFLE criteria in several ways. The RIFLE criteria are defined as changes within 7 days, while the AKIN criteria suggest using 48 hours. The AKIN classification includes less severe injury in the criteria and AKIN also avoids using the glomerular filtration rate as a marker in AKI, as there is no dependable way to measure glomerular filtration rate and estimated glomerular filtration rate are unreliable in AKI.

- Haase et al. 2009 in their comparative study between RIFLE and AKIN in cardiac surgery; found no difference between the AKI scores11.