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Defining an Intraoperative Hypotension Threshold in Association with De Novo Renal Replacement Therapy after Cardiac
Janet M C Ngu1, Habib Jabagi, Amy M Chung
1From the Division of Cardiac Surgery (J.M.C.N., H.J., M. Boodhwani, M.R.) the Division of Cardiac Anesthesiology (A.M.C., M. Bourke, L.Y.S.) Cardiocore Big Data Research Unit (L.Y.S.), University of Ottawa Heart Institute, Ottawa, Canada the School of Epidemiology and Public Health, University of Ottawa, Ottawa, Canada (L.Y.S.) the Cardiovascular Research Program, Institute for Clinical Evaluative Sciences, Toronto, Canada (L.Y.S.).
Background:
Acute kidney injury (AKI) is a frequent and deadly complication after cardiac surgery. In the absence of effective therapies, a focus on risk factor identification and modification has been the mainstay of management. The authors sought to determine the impact of intraoperative hypotension on de novo postoperative renal replacement therapy in patients undergoing cardiac surgery, hypothesizing that prolonged periods of hypotension during and after cardiopulmonary bypass (CPB) were associated with an increased risk of renal replacement therapy.
Methods:
Included in this single-center retrospective cohort study were adult patients who underwent cardiac surgery requiring CPB between November 2009 and April 2015. Excluded were patients who were dialysis dependent, underwent thoracic aorta or off-pump procedures, or died before receiving renal replacement therapy. Degrees of hypotension were defined by mean arterial pressure (MAP) as less than 55, 55 to 64, and 65 to 74 mmHg before, during, and after CPB. The primary outcome was de novo renal replacement therapy.
Results:
Of 6,523 patient records, 336 (5.2%) required new postoperative renal replacement therapy. Each 10-min epoch of MAP less than 55 mmHg post-CPB was associated with an adjusted odds ratio of 1.13 (95% CI, 1.05 to 1.23; P = 0.002), and each 10-min epoch of MAP between 55 and 64 mmHg post-CPB was associated with an adjusted odds ratio of 1.12 (95% CI, 1.06 to 1.18; P = 0.0001) for renal replacement therapy. The authors did not observe an association between hypotension before and during CPB with renal replacement therapy.
Conclusions:
MAP less than 65 mmHg for 10 min or more post-CPB is associated with an increased risk of de novo postoperative renal replacement therapy. The association between intraoperative hypotension and AKI was weaker in comparison to factors such as renal insufficiency, heart failure, obesity, anemia, complex or emergent surgery, and new-onset postoperative atrial fibrillation. Nonetheless, post-CPB hypotension is a potentially easier modifiable risk factor that warrants further investigation.
Insights
Intraoperative hypotension after cardiopulmonary bypass increases the risk of acute kidney injury requiring renal replacement therapy. Lower mean arterial pressure post-cardiac surgery is a modifiable risk factor for kidney complications.
Area of Science:
- Nephrology
- Cardiology
- Critical Care Medicine
Background:
- Acute kidney injury (AKI) is a significant complication following cardiac surgery.
- Effective therapies for AKI are limited, emphasizing risk factor management.
- Intraoperative hypotension is a potential contributor to AKI after cardiac surgery.
Purpose of the Study:
- To investigate the association between intraoperative hypotension and the need for de novo postoperative renal replacement therapy (RRT).
- To determine the impact of hypotension during and after cardiopulmonary bypass (CPB) on RRT requirements.
Main Methods:
- A single-center retrospective cohort study included adult patients undergoing cardiac surgery with CPB.
- Mean arterial pressure (MAP) thresholds (<55, 55-64, 65-74 mmHg) were used to define hypotension before, during, and after CPB.
- The primary outcome was de novo RRT in the postoperative period.
Main Results:
- 5.2% of 6,523 patients required new postoperative RRT.
- Each 10-minute period of MAP <55 mmHg post-CPB increased RRT odds by 1.13 (aOR=1.13; 95% CI, 1.05-1.23; P=0.002).
- Each 10-minute period of MAP 55-64 mmHg post-CPB increased RRT odds by 1.12 (aOR=1.12; 95% CI, 1.06-1.18; P=0.0001).
- Hypotension before and during CPB was not associated with RRT.
Conclusions:
- MAP <65 mmHg for ≥10 minutes post-CPB is linked to a higher risk of de novo postoperative RRT.
- Post-CPB hypotension is a potentially modifiable risk factor for AKI after cardiac surgery.
- The association of hypotension with AKI is less pronounced than other factors like renal insufficiency or heart failure.
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