hypotension matters
Intraoperative hypotension and
outcomes after noncardiac surgery
Intraoperative hypotension and outcomes after noncardiac surgery

Recent studies show associations between intraoperative hypotension and increased risk of acute kidney injury (AKI) and myocardial injury 1-3 — the leading cause of post-operative mortality within 30 days after surgery.1

Prolonged exposures below mean arterial pressure (MAP) thresholds of 65 mmHg are associated with increased risk of myocardial injury and AKI after noncardiac surgery.1

increased risk of mortality associated with hypotension after noncardiac surgery

Studies also show an increased risk of mortality associated with hypotension after noncardiac surgery.4,5

If it were considered its own category, post-operative mortality would be the third leading cause of death in the United States.6

Hypotension study findings
point to increased risk

Highlights from 2017 Salmasi, et al.1

Publication in Anesthesiology: “Relationship Between Intraoperative Hypotension, Defined by Either Reduction From Baseline or Absolute Thresholds, and Acute Kidney and Myocardial Injury After Noncardiac Surgery”

In a study conducted by the Cleveland Clinic, researchers found that intraoperative hypotension is associated with clinical outcomes after noncardiac surgery.

Hypotension study findings point to increased risk

Mean arterial pressure (MAP) below absolute thresholds of 65 mmHg or relative thresholds of 20% or more below baseline were progressively related to both myocardial and acute kidney injury (AKI). At any given threshold, prolonged exposure was associated with increased odds.

maintaining intraoperative MAP greater than 65 mmHg may reduce the risk of AKI and myocardial injury

Absolute and relative MAP thresholds had comparable ability to discriminate patients with myocardial or kidney injury from those without. The results suggest that maintaining intraoperative MAP greater than 65 mmHg may reduce the risk of AKI and myocardial injury.

Lowest mean arterial pressure (MAP) thresholds for myocardial injury
after noncardiac surgery (MINS)

Univariable and multivariable relationship between MINS and absolute and relative lowest MAP thresholds. (A) and (C) Estimated probability of MINS were from the univariable moving-window with the width of 10% data; (B) and (D) were from multivariable logistic regression smoothed by restricted cubic spline with three degrees and knots at 10th, 50th, and 90th percentiles of given exposure variable. Multivariable models adjusted for covariates in the table below. (A) and (B) show that there was a change point (i.e., decreases steeply up and then flattens) around 65 mmHg, but 20% was not a change point from (C) and (D).

Lowest mean arterial pressure (MAP) thresholds for acute kidney injury (AKI) after noncardiac surgery

Univariable and multivariable relationship between AKI and absolute and relative lowest MAP thresholds. (A) and (C) Estimated probability of AKI were from the univariable moving-window with the width of 10% data; (B) and (D) were from multivariable logistic regression smoothed by restricted cubic spline with three degrees and knots at 10th, 50th, and 90th percentiles of given exposure variable. (A) and (B) show that there was a change point (i.e., decreases steeply up and then flattens) around 65 mmHg, but 20% was not a change point from (C) and (D).

MINS
AKI
MINS

Lowest mean arterial pressure (MAP) thresholds for acute kidney injury (AKI) after noncardiac surgery

Univariable and multivariable relationship between AKI and absolute and relative lowest MAP thresholds. (A) and (C) Estimated probability of AKI were from the univariable moving-window with the width of 10% data; (B) and (D) were from multivariable logistic regression smoothed by restricted cubic spline with three degrees and knots at 10th, 50th, and 90th percentiles of given exposure variable. (A) and (B) show that there was a change point (i.e., decreases steeply up and then flattens) around 65 mmHg, but 20% was not a change point from (C) and (D).

AKI

Additional Research Findings

Physiology of perfusion:
pressure and flow
adequate perfusion

Adequate perfusion requires adequate arterial pressure and cardiac output (CO)

cardiac output

Cardiac Output (CO) =
Stroke Volume x Heart Rate

Managing the flow component of perfusion

How you manage volume matters

Preload

Preload: the tension of myocardial fibers at the end of diastole, as a result of volume in the ventricle

Stroke Volume

Stroke Volume (SV): volume of blood pumped from the left ventricle per heartbeat

When managing perfusion, stroke volume can be “optimized” using the patient’s own Frank-Starling curve — a plot of stroke volume (SV) vs. preload.

Stroke volume graph

The patients location on his or her Frank-Starling curve can be determined by measuring ∆SV in response to change in preload using:

Bolus fluid challenge

Bolus fluid challenge

Passive leg raise (PLR)

Passive leg raise (PLR)

Additionally, stroke volume variation (SVV) has been proven to be a highly sensitive and specific indicator for preload responsiveness when managing volume. As a dynamic parameter, SVV has been shown to be an accurate predictor of fluid responsiveness in loading conditions induced by mechanical ventilation.7,8,9

Stroke volume graph

To learn more about managing fluid with advanced parameters, visit our page on fluid management and perioperative goal directed therapy

Click Here

Reducing fluid variability using Perioperative
Goal-Directed Therapy (PGDT)

PGDT

PGDT is a treatment protocol using dynamic and flow-based parameters with the objective of making the appropriate volume management decisions (e.g. fluid only when needed).7

PGDT can be implemented in a single procedure or as part of a larger initiative such as Enhanced Recovery After Surgery pathways.

To learn more about volume management and PGDT,

Click Here

Edwards clinical education
Edwards clinical education

Hemodynamic education for sustained clinical advancement

With a long-term commitment to improving the quality of care for surgical and critical care patients through education, Edwards Clinical Education meets you no matter where you are in the learning process — with a continuum of resources and tools that continuously support you as you solve the clinical challenges facing you today, and in the future.

For more educational information.

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References
  1. Salmasi, V., Maheshwari, K., Yang, G., Mascha, E.J., Singh, A., Sessler, D.I., & Kurz, A. (2017). Relationship between intraoperative hypotension, defined by either reduction from baseline or absolute thresholds, and acute kidney injury and myocardial injury. Anesthesiology, 126(1), 47-65.
  2. Sun, L.Y., Wijeysundera, D.N., Tait, G.A., & Beattie, W.S. (2015). Association of Intraoperative Hypotension with Acute Kidney Injury after Elective Noncardiac Surgery. Anesthesiology, 123(3), 515-523.
  3. Walsh, M., Devereaux, P.J., Garg, A.X., Kurz, A., Turan, A., Rodseth, R.N., Cywinski, J., Thabane, L., & Sessler, D.I. (2013). Relationship between Intraoperative Mean Arterial Pressure and Clinical Outcomes after Noncardiac Surgery. Anesthesiology, 119(3), 507-515.
  4. Mascha, E.J., Yang, D., Weiss, S., & Sessler, D.I. (2015). Intraoperative Mean Arterial Pressure Variability and 30-day Mortality in Patients Having Noncardiac Surgery. Anesthesiology, 123(1), 79-91.
  5. Monk, T.G., Bronsert, M.R., Henderson, W.G., Mangione, M.P., Sum-Ping, S.T.J., Bentt, D.R., Nguyen, J.D., Richman, J.S., Meguid, R.A., Hammermeister, K.A., (2015). Association between Intraoperative Hypotension and Hypertension and 30-day Postoperative Mortality in Noncardiac Surgery. Anesthesiology, 123(2), 307-319.
  6. Devereaux, P.J., Sessler, D.I., (2015). Cardiac Complications in Patients Undergoing Major Noncardiac Surgery, N Engl J Med, 373(23), 2258-2269.
  7. Peng, K., Li, J., Cheng, H., Ji, FH. (2014) Goal-directed fluid therapy based on stroke volume variations improves fluid management and gastrointestinal perfusion in patients undergoing major orthopedic surgery. Medical Principles and Practice, 23(5), 413-20.
  8. Berkenstadt, H., et al. (2001) Stroke Volume Variation as a Predictor of Fluid Responsiveness in Patients Undergoing Brain Surgery. Anesthesia & Analgesia, 92, 984-9
  9. Michard, F., Mountford, W., Krukas, M., Ernst, F., Fogel, S. (2015) Potential return on investment for implementation of perioperative goal-directed fluid therapy in major surgery: a nationwide database study. Perioperative Medicine, 4, 11.

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