Monday, February 17, 2014

DREAM-CARD. Diuresis Related Endpoints After Major CARDiac surgery

This is my contribution to the Dream RCT in Nephrology poll being coordinated by UKidney. As a nephrologist it seems one spends a lot of time trying to rationalize the use of diuretics in the Cardio-Thoracic ICU. Volume overload and reduction in preload are common and very valid concerns for patients post cardiac surgery. Diuresis to remedy this problem is a physiologically appropriate management strategy. However, as a nephrologist it is not uncommon to see patients that have been diuresed to the point where renal perfusion is compromised. Admittedly this is anecdotal and we see a biased group of cardiac surgery patients. There is evidence that an episode of dialysis requiring AKI in any hospitalized patient increases risk of progression to CKD even if renal function recovers enough for the patient to come off dialysis.

Cardiovascular, renal and survival outcome data for dialysis-requiring AKI in post cardiac surgery patients with relatively preserved pre-op GFR is lacking. It is possible that increased renal outcomes or mortality associated with dialysis-requiring AKI in this group of patients may offset any benefits achieved by cardiac surgeries such as CABG and valve repair. This is the motivation for this ‘dream’ trial. Conducting such a trial would be a very large and difficult undertaking due to the many sources of bias in such a trial and also the fact that blinding a trial involving a dialysis machine is impossible. This would be a very difficult trial to roll out in the real world but here is my best effort!

Inclusion criteria;
Preoperative eGFR over 60ml/min (MDRD)
Elective non-transplant cardiac surgery

Exclusion criteria;
Previous cardiothoracic surgery Macroalbuminuria or greater
Previous AKI events Hospitalizations in the preceding 6 months
Aortic cross clamp time longer than usual as judged by blinded independent panel
Unexpected intraoperative complications as judged by blinded independent panel
Patients requiring RE-intubation after the initial perioperative period (removed from final analysis)

Interventions: The interventions will be randomized into two arms determined by Central Venous Pressure (CVP).
Target CVP: 1) Below 6mmHg versus 2) Below 12mmHg

The approach used to reach this target maybe be determined by the individual clinician. Use of IV Lasix infusion, IV Lasix bolus, concomitant thiazide use or dialysis for the purposes of ultrafiltration (UF) will be documented. Total doses of Lasix and number of days Lasix was used will be documented. Total daily UF achieved by dialysis and number of days on dialysis will be documented. Whether continuous RRT therapy or intermittent therapy was used will also be documented. All the usual demographics and variables will be documented such as serial body weights, urine outputs, blood pressures, serum creatinines and number of days in hospital.

Post discharge patients will be followed. All post surgical hospital admissions and diagnoses will be documented. If patients had elevated creatinines at discharge, serial monthly creatinines will be measured until stable. If patients are discharge home but still on dialysis, the number of days on dialysis before recovery will be documented. The dialysis status of those remaining on dialysis will be followed. All patients will be followed with a yearly creatinine (MDRD). Follow up will be for five years.

The primary endpoint will be mortality
The secondary endpoint will be a composite of renal endpoints including the development of CKD and ESRD.

The goal will be to determine if those who underwent aggressive postoperative volume reduction as assessed by CVP have increased mortality. Furthermore, will those who required mechanical UF to reach their CVP goal have worse renal outcomes?
Remember readers this is a ‘DREAM’ trial, one that is likely never to happen especially as the funding source will be from the large coffers of the RFN! Another major benefit of doing such a trial would be the accumulation of a large amount of useful data.
Vote for DREAM-CARD, badly needed evidence for rounding in the CT-ICU!

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