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Acute kidney injury in post operative cardiac surgery patients is seen
in up to 40% of patients with 1% requiring hemodialysis long term and
is associated with increased morbidity and mortality
(M&M)7,8. Fluid overload in post operative cardiac
surgery patients is also associated with increased
M&M1,9. This perioperative “temporary kidney injury
state” during post cardiac surgery has been studied extensively and is
associated with increased need for resources, increased length of stay,
urgent renal consultations, and a relatively higher failure to rescue
(FTR) rate when compared to other complications2-4,9.
The current options available for the treatment of AKI with or without
fluid overload in post operative cardiac surgery patients are limited
and include escalating diuretics, continuous renal replacement therapy
(CRRT), simple ultrafiltration technology (to remove isotonic plasma)
and hemodialysis, each with their associated risks and benefits.
Modified ultrafiltration (MUF) was developed over the last two decades
and used intraoperatively while on the cardiopulmonary bypass circuit to
remove excess fluid in both adult and pediatric cardiac surgery
patients. Simplified ultrafiltration technology using an extracorporeal
circuit has been in clinical use for more than a decade and its
efficiency has been extensively studied in heart failure clinical trials
(i.e., UNLOAD, AVOID-HF, EUPHORIA)13. More recently,
US clinical trials and the Food and Drug Administration approval were
granted for the treatment of fluid overload in the pediatric population
weighing ≥20 Kg. CRRT is the mode of choice over conventional
hemodialysis for post operative cardiac surgery patients due to improved
hemodynamic tolerance14.
Adult cardiac surgery patients mostly present acutely after many years
of chronic medical conditions and modifiable risk factors including HTN,
DM, obesity, hyperlipidemia, physical inactivity, and smoking. HTN and
DM were seen in 88% and 76% of our 17 UF patients, respectively. The
long-term deleterious effect of HTN and DM on renal function is
underestimated in patients with cardiovascular diseases since both
chronic diseases are found in most patients requiring hemodialysis. The
term cardiorenal syndrome also describes the inter-organ
pathophysiological relationships in the setting of fluid
overload15,16. Mortality scoring systems and online
calculators are used more frequently to risk stratify and predict
outcomes of surgery. These scoring systems provide a guide and
underscore the various phases of care, multi-disciplinary knowledge,
available skills, hospital structure, processes, available equipment,
staffing ratios and complexity that is inherent in cardiac surgery.
Coronary artery bypass grafting surgery is the most common open heart
surgery procedure performed for the treatment of coronary artery disease
and its outcomes are used as a quality indicator for the
hospitals4. Since AKI has been reported to occur in up
to 40% of patients undergoing cardiac surgery and has the highest
failure to rescue rates of post cardiac surgery complications, more
incite is needed to improve this quality metric3,7,8.
The care of these patients has evolved with the application of newer
monitoring technology, devices, artificial intelligence, and processes
to improve overall outcomes. Implementation of a cardiac Enhanced
Recovery after Surgery (ERAS) protocol is one example of process
improvement using goal directed therapy with emphasis on avoidance of
excess sodium and water overload. Although prevention of fluid overload
intra-operatively is preferable, it is still seen as a common
denominator in post cardiac surgery patient’s complications.
Fortunately, most cardiac ICUs in the immediate post-operative setting
is equipped with hemodynamic monitoring, critical care expertise and
protocols to care for any possible complication. Due to the high FTR
rates for AKI, close monitoring of these patients is essential for
improved survival.
Our entire CABG population (254 patients, which included the COVID-19
pandemic) had a mean STS mortality score of 2.5 ± 6.61% whereas, the
subset (17 patients) that underwent UF therapy had a mean STS score of
5.7 ± 11.55%. Despite the higher mortality STS score for the UF group,
there was a favorable survival outcome (100%). In addition to the
mortality benefits, real time advantage of UF therapy (Table 4) include:
quick set up (15 to 30 minutes) any time of day, night, weekend or
holiday; no immediate need for renal consultation unless RRT is needed;
use of existing venous access placed intra-operatively during the
initial CABG procedure or a new peripheral cannula can be placed (see
Figure 1 and 2), the set-up is very simple relative to other RRT devices
and is done by the ICU bedside nurse with no additional nursing staff.
The volume to be removed is adjustable (hour to hour as needed) and the
machine records the amount of fluid removed every hour thereby improving
ICU nursing labor efficiency without the need for volume calculations.
The total extracorporeal blood is approximately 35cc within the circuit
limiting blood loss if UF is discontinued. Of note, this study period
included the COVID-19 pandemic period and the use of Aquadex UF system
freed up CRRT/HD resources for other critical care patients since no
increased nursing staff was needed to perform UF.
This small retrospective pilot study shows the safety of using this UF
technology to remove excess isotonic plasma water from patients in a
highly monitored setting in the post-operative phase of cardiac surgery
care with great outcomes. A larger multi-institutional study including
long term follow up of high-risk patient populations is warranted.
References:
- Koc V, Benito LD, de With E, Boerma EC. The Effect of Fluid Overload
on Attributable Morbidity after Cardiac Surgery: A Retrospective
Study. Critical Care Research and Practice Volume 2020, 1-7.
- Edwards FH, Ferraris VA, Kurlansky PA, Lobdell KW, He X, O’Brien SM,
Furnary AP, Rankin JS, Vassileva CM, Fazzalari FL, Magee MJ, Badhwar
V, Xian Y, Jacobs JP, von Ballmoos MCW, Shahian DM. Failure to Rescue
Rates After Coronary Artery Bypass Grafting: An Analysis From The
Society of Thoracic Surgeons Adult Cardiac Surgery Database. Ann
Thorac Surg 2016;102:458–64.
- Crawford TC, Magruder JT, Grimm JC, Suarez-Pierre A, Sciortino CM,
Mandal K, Zehr KJ, Conte JV, Higgins RS, Cameron DE, Whitman GJ.
Complications After Cardiac Operations: All Are Not Created Equal. Ann
Thorac Surg 2017;103:32–40.
- Bowdish ME, D’Agostino RS, Thourani VH, Schwann TA, Krohn C, Desai N,
Shahian DM, Fernandez FG, Badhwar V. STS Adult Cardiac Surgery
Database: 2021 Update on Outcomes, Quality, and Research. Ann Thorac
Surg 2021;111:1770-80.
- Wang Y, Bellomo R. Cardiac surgery-associated acute kidney injury:
risk factors, pathophysiology and treatment. NATURE REVIEWS,
NEPHROLOGY VOLUME 13, NOVEMBER 2017, Pg 697-711.
- Pal S. Primary Causes of End-Stage Renal Disease. US Pharm.
2016;41(8):6.
- Vives M, Hernandez A, Parramon F, Estanyol N, Pardina B, Muñoz A,
Alvarez P, Hernandez C. Acute kidney injury after cardiac surgery:
prevalence, impact and management challenges. International Journal of
Nephrology and Renovascular Disease 2019:12 153–166.
- Matsuura R, Iwagami M, Moriya H, Ohtake T, Hamasaki Y, Nangak M, Doi
K, Kobayashi S, Noiri E. The Clinical Course of Acute Kidney Disease
after Cardiac Surgery: A Retrospective Observational Study. Scientific
Reports (2020) 10:6490.
- Xu J, Shen B, Fang Y, Liu Z, Zou J, Liu L, Wang C, Ding X, Teng J.
Postoperative Fluid Overload is a Useful Predictor of the Short-Term
Outcome of Renal Replacement Therapy for Acute Kidney Injury After
Cardiac Surgery. Medicine 94(33):e1360.
- Halkos ME, Puskas JD, Lattouf OM, Kilgo P, Kerendi F, Song HK, Guyton
RA, Thourani VH. Elevated preoperative hemoglobin A1c level is
predictive of adverse events after coronary artery bypass surgery. J
Thorac Cardiovasc Surg 2008;136:631-40.
- Engelman DT, Ali WB, Williams JB, Perrault LP, Reddy VS, Arora RC,
Roselli EE, Khoynezhad A, Gerdisch M, Levy JH, Lobdell K, Fletcher N,
Kirsch M, Nelson G, Engelman RM, Gregory AJ, Boyle EM. Guidelines for
Perioperative Care in Cardiac Surgery Enhanced Recovery After Surgery
Society Recommendations. JAMA Surg. 2019;154(8):755-766.
- Lobdell KW, Chatterjee S, Sander M. Goal-Directed Therapy for Cardiac
Surgery. Crit Care Clin 36 (2020) 653–662.
- Kazory A. Ultrafiltration Therapy for Heart Failure: Balancing Likely
Benefits against Possible Risks. Clin J Am Soc Nephrol. 2016 Aug 8;
11(8): 1463–1471.
- Borisov AS, Malov AA, Kolesnikov SV, Lomivorotov VV. Renal Replacement
Therapy in Adult Patients After Cardiac Surgery. Journal of
Cardiothoracic and Vascular Anesthesia 33 (2019) 2273-2286.
- Rangaswami J, Bhalla V, Blair JEA, Chang TI, Costa S, Lentine KL,
Lerma EV, Mezue K, Molitch M, Mullens W, Ronco C, Tang WHW, McCullough
PA, Chair On behalf of the American Heart Association Council on the
Kidney in Cardiovascular Disease and Council on Clinical Cardiology.
Cardiorenal Syndrome: Classification, Pathophysiology, Diagnosis, and
Treatment Strategies A Scientific Statement From the American Heart
Association. Circulation. 2019;139:e840–e878.
- Husain-Syed F, Quattrone MG, Ferrari F, Bezerra P, Lopez-Giacoman S,
Danesi TH, Samoni S, de Calb M, Yücel G, Yazdani B, Seeger W, Walmrath
H-D, Birk H-W, Salvador L, Ronco C. Clinical and Operative
Determinants of Acute Kidney Injury after Cardiac Surgery. Cardiorenal
Med 2020;10:340–352.
- Koyner JL, Garg AX, et al and for the TRIBE-AKI Consortium. Biomarkers
Predict Progression of Acute Kidney Injury after Cardiac Surgery
J Am Soc Nephrol. 2012 May; 23(5): 905–914.