Wednesday, November 13, 2013
INCIDENCE AND PREDICTORS OF POST OPERATIVE
ACUTE KIDNEY INJURY IN NON CARDIAC SURGERY
Dr. AKKINENI LOKESH
DEPARTMENT OF ANAESTHESIOLOGY
UNDER THE GUIDANCE OF
DR. CHAITRI SHAH
DEPARTMENT OF ANAESTHESIOLOGY
SBKS MEDICAL INSTITUTE & RESEARCH CENTRE
SUMANDEEP VIDYAPEETH UNIVERSITY
PIPARIA, VADODARA, GUJARAT
AKI is sudden impairment of kidney function resulting in the retention of nitrogenous and other waste products normally cleared by the kidneys. Kidneys maintain water and solute homeostasis, guarding the body’s internal mileu.'' AKI is not a single disease but, rather, a designation for a heterogeneous group of conditions that share common diagnostic features: specifically, an increase in the blood urea nitrogen (BUN) concentration and/or an increase in the plasma or serum creatinine (SCr) concentration, often associated with a reduction in urine volume. Sudden disruption of previously normal or stable kidney function usually occurring over hours or days'' is termed acute renal failure. ARF can occur in setting of antecedent chronic renal insufficiency. Clinically manifested by oliguria, rise in blood urea and creatine, acidosis and electrolyte imbalance. AKI complicates 5–7% of acute care hospital admissions and up to 30% of admissions to the intensive care unit.
In cardiac surgery, baseline renal function is likely the most important determinant of
postoperative AKI, particularly severe AKI requiring dialysis. Additionally, the cardiovascular status of the patient also inﬂuences the postoperative AKI risk. For example, functional status of congestive heart failure, presence of peripheral vascular disease, and preoperative use of intra-aortic balloon pump have all been associated with increased risk of AKI. Other co-morbid conditions such as diabetes, along with the extent of glycemic control are also independently associated with development of AKI after surgery.[3, 4]
Whereas, In non cardiac surgery, risk factors for AKI have been identiﬁed. Kheterpal et al, studied patients with preoperative normal renal function for non cardiac surgery and developed a preoperative renal-risk index that identiﬁed the following independent risk factors for renal failure: age, emergent surgery, liver disease, body mass index, high-risk surgery, peripheral vascular occlusive disease, and chronic obstructive pulmonary disease (requiring chronic bronchodilator therapy). It is well known that ARF can be associated with vascular surgery. Baseline renal function, ischemia time (aortic cross-clamp time), and intraoperative hypotension are key determinants of postoperative AKI in this setting.
We also hypothesized that incidence of post op AKI in the preoperatively normal renal function in Non-cardiac surgery can be identified early by various Pre-operative and Intra operative predictors, to have them in mind will be useful to prevent adverse post operative outcome related to AKI.
AIMS AND OBJECTIVES OF STUDY:
· Incidence of Acute Kidney Injury in post operative non cardiac surgical patients with base line normal renal function.
· To predict and identify the risk factors with base line normal renal function.
REVIEW OF LITERATURE:
Incidence of Preoperative AKI
Until recently, the definition of AKI was not standardized. Authors have used terms such as renal insufficiency, renal dysfunction, acute renal failure (ARF), and renal failure requiring dialysis somewhat interchangeably. Parameters used to define these terms include absolute creatinine values, absolute and percentage changes in creatinine values, absolute and percentage changes in estimated glomerular filtration rates (GFR), and reduction in urine output. The term ‘‘acute kidney injury’’ has been recently introduced in 2 different classification systems.
Acute Kidney Injury
Net work Criteria
Or Cr 150% baseline
For 6 h
Increased Cr 1.5
Or GFR decreased 25%
UOP < 0.5ml/kg/h
Increased Cr 2
Or GFR decreased 50%
Cr >300% of baseline or 4mg/dl with 0.5mg/dl acute increase
Increased Cr 3 or GFR decreased <75% or Cr>4mg/dl with 0.5mg/dl acute increase
For 24h or
Anuria for 12h
As seen in Table 1, these definitions include creatinine change, GFR change, and measurements of urine output. The first system was the RIFLE criteria (with worsening function progressing from Risk to Injury to Failure to Loss to End-Stage Renal Failure) of the Acute Dialysis Quality Initiative.
More recently, the Acute Kidney Injury Network, a consensus panel involving national and international societies in nephrology and critical care, proposed standard definitions of AKI, and graded the severity of kidney injury into 3 stages. These criteria define AKI as an increase in serum creatinine level by 0.3 mg/dL (or 1.5 times) relative to baseline. Subsequently, the severity is divided into 3 stages based on degree of creatinine elevation (stage I–1.5 to 2 times increase; II– >2 to 3 times increase; and III– >3 times increase, new requirement of dialysis, or an absolute creatinine value of >4 mg/dL with at least a 0.5 mg/dL increment). There are caveats to these criteria, in that they await broader validation across all patient care settings.
Compared to the RIFLE criteria, the AKIN criteria do not materially improve the sensitivity, robustness and predictive ability of the definition and classification of AKI in the first 24 h after admission to ICU .
The rate of perioperative AKI is difficult to know precisely as it is dependent on definitions used and type of surgery studied. In cardiac surgery, rates of kidney injury range between 7.7% and 11.4%[4,9,10] when defined broadly, Kheterpal et al recently studied a noncardiac surgery population with pre- operative normal renal function and noted an incidence of renal failure defined by GFR less than 50 mL/min as 0.8%. After aortic aneurysm repair, incidences of renal failure of various definitions have been reported at 15% to 46%[11,12].Expectedly, the incidence of AKI after cardiac transplant is generally higher than non transplant cardiac surgery; in a single center study involving over 750 cardiac transplants the incidence of AKI requiring dialysis was 6%. On the basis of historical comparisons, this observation was about 6-fold higher than nontransplant cardiac surgery performed during the same time period at that institution.
Impact of AKI on Mortality: A Case for Preoperative Assessment
Postoperative AKI is one of the most serious complications during hospitalization, increasing morbidity, mortality, length of stay, and costs of care.
When AKI occurs preoperatively, morbidity and mortality increase. In cardiac surgery many studies have reported increased mortality related to renal failure requiring dialysis. Zanardo et al reported a mortality rate of 0.8% in patients without renal dysfunction, 9.5% mortality rate with renal dysfunction, and 44.4% in patients with renal failure. Some have reported mortality as high as 89% when renal failure occurs after cardiac procedures.
In noncardiac surgery, AKI also substantially worsens outcomes. It is notable that in a retrospective study of more than 15,000 patients without preexisting renal dysfunction the 30-day, 60-day, and 1-year mortality increased from 2.7% to 15%, 5.1% to 17%, and 15% to 31%, respectively in patients who developed ARF. Factors that have been found to adversely affect survival include the need for ionotropic support, ventilation for more than 3 days or failure to wean from mechanical ventilation, age greater than 65, vascular disease score, need for additional surgery, and the presence of systemic inflammatory response syndrome or multi- organ failure.[14,12,15]
Preoperative Risk Factors
It can be hypothesized that AKI after a surgical procedure results from preoperative comorbid status, the type of surgical procedure, and immediate postoperative course. Regarding the preoperative risk factors of AKI, advanced age is consistently associated with increased risk of AKI, regardless of the clinical setting.[5,12,16-19] In cardiac surgery, baseline renal function is likely the most important determinant of postoperative AKI, particularly severe AKI requiring dialysis. Additionally, the cardiovascular status of the patient also influences the postoperative AKI risk. For example, functional status of congestive heart failure, presence of peripheral vascular disease, and preoperative use of intra-aortic balloon pump have all been associated with increased risk of AKI. Other comorbid conditions such as diabetes, along with the extent of glycemic control are also independently associated with development of AKI after surgery.
In noncardiac surgery, different risk factors for AKI have been identified. As previously cited, Kheterpal et al studied patients with preoperative normal renal function for noncardiac surgery and developed a preoperative renal-risk index that identified the following independent risk factors for renal failure: age, emergent surgery, liver disease, body mass index, high-risk surgery, peripheral vascular, Occlusive disease, and chronic obstructive pulmonary disease (requiring chronic bronchodilator therapy). On the basis of the incremental score, the frequency of renal failure increased ranging between 0.3% and 4.5%.
It is well known that ARF can be associated with Baseline renal function, ischemia time (aortic cross-clamp time), and intraoperative hypotension are key determinants of postoperative AKI in this setting.
Intraoperative Risk Factors
Several intraoperative risk factors have been associated with AKI. These factors are difficult to quantify, unless they were meticulously recorded during the surgery, and may still represent as surrogate for unmeasured events during the surgical procedure.
In noncardiac surgery, there are fewer studies describing intra- operative risk factors that are independently associated with AKI. Kheterpal et al determined if the intraoperative risk factors of use of a vasopressor infusion, mean number of vasopressor bolus doses administered, and the administration of furosemide or mannitol were added to the analysis. In it they included the intraoperative risk factors of units of packed red blood cells required, hypotension defined as mean arterial pressure less than 50 mm Hg, Although the value of each of these individual risk factors is unknown, the absence of them is reassuring.
Several events during the postoperative period can influence renal function. The literature in this regard is more difficult to interpret due to the lack of clear temporality between nonrenal events and AKI.
Postoperative serious events also lead to AKI in noncardiac surgery. In vascular surgery, the overall need for ionotropic support and the need for longer postoperative mechanical ventilation have been associated with AKI.[12,15]
There is ample evidence that postoperative AKI is associated with other nonrenal complications, and together, the number of organ failures contributes to an increased mortality risk. Thakar et al (Kidney International 2003) examined postoperative AKI and sepsis/infections. There was increased risk of postoperative infections with worsening degree of severity of AKI.
Albright RC studied, Acute renal failure (ARF) affects in almost all medical specialties. Its occurrence seems to be increasing in hospitalized patients. A structured approach to the evaluation and management of ARF would facilitate rapid diagnosis and treatment in most patients. Appreciation for the multiple drugs that affect renal function is especially important. Exclusion of urinary outflow obstruction and administration of therapies that improve renal perfusion should be given top priority with respect to managing ARF.
Mangano, Christina Mora MD; studied, Acute changes in renal function after elective coronary bypass surgery incompletely characterized and represent a challenging clinical problem determined that patients having elective myocardial revascularization develop postoperative renal dysfunction and failure, which are associated with prolonged intensive care unit and hospital stays, significant increases in mortality, and greater need for specialized long-term care.
Kheterpal et al, studied predictors of postoperative acute renal failure after noncardiac surgery in patients with previously normal renal function . Seven independent preoperative predictors were identified : age, emergent surgery, liver disease, body mass index, high-risk surgery, peripheral vascular occlusive disease, and chronic obstructive
pulmonary disease necessitating chronic bronchodilator therapy. Several intraoperative management variables were independent predictors of acute renal failure: total vasopressor dose
administered, use of a vasopressor infusion, and diuretic administration. Acute renal failure was associated with increased 30-day, 60-day, and 1-yr all-cause mortality. Conclusions: Several preoperative predictors previously reported to be associated with acute renal failure after cardiac
surgery were also found to be associated with acute renal failure after non cardiac surgery. The use of vasopressor and diuretics is also associated with acute renal failure.
MATERIAL AND METHODOLOGY:
Type of Study:
Prospective Observational Study.
DHIRAJ HOSPITAL affliated to SBKS medical Institute and Reasearch Centre
Patients will be selected according to inclusion and exclusion criteria.
The written informed consent will be obtained from them and they will Undergo a complete clinical history and physical examinations
Following details of the patients included in the study will be obtained
· Diagnosis clinical
· Co-morbid condition
· Drug history
· Past history
Pre Operative Investigations :-
· Urine routine
· Urine micro
· Serum creatinine
· Blood Urea
· Serum electrolytes
· Urea Nitrogen
· Estimated GFR- Creatinine clearance using the
Cockcroft-Gault formula-(140-age in years) x(weight in kilograms)
(72x serum creatinine in mg/dl]) x (0.85 for females).
· Other special investigations (If any)
One the day of Surgery following details will be obtained:-
· Nil By Mouth period (NBM- No of Hours)
· Type of Surgery
· Pre operative fluid (Amount)
· Drugs given
· Type of Anesthesia
· Duration of surgery
· Blood loss
· Hypotension (SBP < 90 mm of Hg)
· Bolus fluid
· Urine output
· Urine output total on the day for 72 Hrs
· Renal Function Test – Day 1 to 3
· Primary outcome
· Post operative AKI will be defined and classify as per RIFLE CRITERIA
· Days of hospitalization
· Hospital Outcome - Discharged/ Died
All patients undergoing major Non-cardiac surgeries:
· With Normal serum creatinine levels pre operatively
· Spinal Anesthesia
· Epidural Anesthesia
· General Anesthesia
All patients undergoing
· Cardiac surgeries
· Vascular surgeries
· Deranged baseline Kidney function
· Radiological contrast prior 48 hrs
INVESTIGATIONS TO BE DONE:
Ø Complete blood count
Ø Renal Function Test
Ø Serum electrolytes
Ø Random blood sugar
Ø Blood Urea Nitrogen
Ø Urine Routine/Microscopy
Ø Random blood sugar
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