Anesthesiologists should place greater emphasis on blood pressure control during the perioperative period, because success or failure in achieving postoperative blood pressure targets can have significant effects on short- and long-term outcomes.
Recent studies have linked acute alterations in perioperative blood pressure to adverse outcomes in cardiac surgery, including acute kidney injury, higher mortality rate and longer hospital stay. A study from Germany, presented at the annual meeting of the Society of Cardiovascular Anesthesiologists (abstract 17), sought to identify any association between postoperative blood pressure control and acute kidney injury specifically. Researchers retrospectively evaluated 5,225 cardiac surgery patients who underwent procedures between 2006 and 2012 at Charite Hospital, in Berlin. All patients were admitted to the cardiac surgical ICU following surgery and, in all cases, invasive blood pressure measurements were recorded until ICU discharge.
For grouping purposes, the researchers used cumulative systolic blood pressure readings that fell outside a defined target range of 100 to 130 mm Hg. They performed matched pair comparative analysis of outcome measurements between normotensive and hypertensive groups and, to eliminate confounding factors, selected 1:1 matched case (hypertensive) and control (normotensive) groups by identifying patients with similar baseline profiles and disease characteristics (age, surgery type and duration, preoperative glomerular filtration rate, diabetes mellitus, preexisting hypertension and APACHE [Acute Physiology and Chronic Health Evaluation] II score on ICU admission).
Acute Kidney Injury and Mortality Higher
In all, 891 patients (17.1%) were classified as hypertensive, and matched pairs for 604 of the hypertensive patients were identified in the normotensive group. The authors found that hypertensive patients had an increased risk for death (4.97% vs. 1.32%; P<0.001), stayed an average of one day longer in the hospital (P=0.024) and had a greater incidence of renal dysfunction (25.3% vs. 19.7%;P=0.027) as well as elevated levels of serum creatinine compared with normotensive patients. Interestingly, 30-day survival also differed significantly (P=0.002) between the groups, and hypertension was associated with death with a hazard ratio of 8.9 (P=0.001).
“The important and somewhat unexpected finding was that postoperative hypertension, conservatively defined in a typical clinical care setting, was strongly associated with adverse outcomes, including acute kidney injury as well as death, in patients following cardiac surgery,” noted Felix Balzer, MD, MSc, a co-author of the study and professor at Humboldt Universitat, in Berlin. Based on the findings, Dr. Balzer added, he would like to see “much greater sensitivity [among anesthesiologists] to the importance of establishing and following clinical guardrails for postoperative blood pressure management following cardiac surgery.” He said, “A consequence of these tighter guardrails will likely be, and arguably should likely be, the development of less tolerant clinical care management plans for blood pressure swings.”
Dr. Balzer and his team plan to continue research addressing the issue of blood pressure control. Specifically, they hope to explore the feasibility of establishing “optimized blood pressure ranges” based on patients’ individual conditions.
Although he described the findings as “interesting,” Breandan L. Sullivan, MD, co-medical director of the cardiothoracic ICU at University of Colorado Hospital, and assistant professor, Department of Anesthesiology and Critical Care Medicine, University of Colorado School of Medicine, in Aurora, who was not involved in the study, added that there are other factors beyond blood pressure management that have just as significant an effect on patient outcomes.
“In certain surgeries, such as descending thoracic aortic surgery, the patients are treated with permissive hypertension for months postoperatively,” he said. “The type of surgery has much more do to with their mortality and morbidity than their blood pressure measurement in these cases.”