Aim:
TO STUDY PREDICTIVE VALUE
OF RENAL RESISTIVE INDEX FOR DEVELOPMENT OF
POSTOPERATIVE ACUTE KIDNEY INJURY IN PATIENTS UNDERGOING OFF PUMP CABG
Objectives:
Primary objective :
a)
To document the change in RRI following coronary anastomosis in off pump CABG
b)
To determine predict value of RRI for development of
postoperative AKI
Secondary
objective
1.
To document the change in RRI and CVP following
coronary anastomosis in off pump CABG
and determine their combined value to
predict development of postoperative AKI
2.
To correlate the changes in RRI during position of the
heart for circumflex (lateral) and PDA (inferior) anastomosis in off pump CABG
with changes cardiac output, cardiac index, mean arterial pressure and CVP
Study
Methodology :
TEE
probe is routinely inserted after induction of anaesthesia . We use
the TEE probe to scan the kidney and measure the renal resistive index in the
left kidney.
The TEE probe is advanced
approximately 30 cm from the upper incisor teeth, and a standard midesophageal
4-chamber view is obtained. Starting from the 4-chamber view, the probe is
advanced a further 8 to 10 cm to lead it through the short abdominal part of
the oesophagus eventually into the stomach and anteflexed to obtain a
midpapillary transgastric short-axis (TG SAX) view.
STEP 1: TG SAX view is obtained . •
STEP 2: The probe is rotated 90 to 270 degrees toward the LEFT
until the SAX view of the descending
aorta is imaged. The aorta lies
anterior to the oval hypoechogenic vertebral body
STEP 3: The probe is advanced 4–6 cm following
the aorta to the origin of the left renal artery Colour flow doppler is
used to image the blood flow in left
renal vessels.
STEP 4 : Pulse wave doppler is used to measure
the RRI as follows :
Use
of ionotropes , fluids or vasodilators to maintain haemodynamic stability is
managed by the concerned anaesthesiologists. After steadying of hemodynamic
changes due to positioning and stabilization of the heart with octopus for
anastomosis of obtuse marginal (OM) and posterior descending artery (PDA), change
in the left kidney RRI are noted. Final left RRI is recorded after protamine reversal of heparin.
Systemic
hemodynamic changes are manifested in both the kidneys .As left kidney is easy
to scan we measure only left RRI.
TEE guided Left Renal Resistive Index (RRI) will be measured as follows
a.
Baseline T0
:measured after induction and steady state haemodynamics for 5 mins
b.
During anastomosis
of OM -T1
c.
During anastomosis
of PDA-T2
d.
After reversal of
heparin with protamine .-T3
AKI
will be diagnosed using criteria proposed by Acute
Kidney Injury Network (AKIN) as an abrupt (within 48 h)
absolute increase in the serum creatinine concentration of ≥0.3 mg/dL from
baseline, a percentage increase in serum creatinine of ≥50%, or oliguria of
less than 0.5 mL/kg/hr for more than 6 h14 AKI will be defined using the AKIN criteria by comparing
the highest serum creatinine within 48 h after surgery with preoperative serum
creatinine
Recovery from AKI will be
defined as a 50 percent decrease in serum creatine or return of serum creatine
to its baseline value.
.
Patients who meet the
AKIN criteria for AKI are classified as “AKIâ€, whereas those who do not are classified as “no AKIâ€.
For analysis study population will be grouped
as follows
1. No
AKI
2. Transient
AKI:
Transient
AKI will be defined as recovery from AKI within 3 days after surgery.
Persistent AKI : will be defined as persistent elevation of serum creatine after
3 days.
Intraoperative
Parameters recorded will be
1.
Left RRI
2.
Cardiac output and
cardiac index as measured by flowtrac
3.
Mean arterial
pressure (MAP)
4.
CVP
Post operative
parameters recorded will be
Sr creatine
and Urine out put :for 3 days if no AKI
; or till 5 days if AKI develops.
Statistical analysis
Results will be expressed
as median with range, number with
proportion (%), percentage with standard deviation as appropriate.
Pearson’s test will be used to study the
correlations. A receiver-operating characteristic curve (ROC) will be generated
for RRI in each AKI group to test the significance of RRI as a diagnostic tool. |