Perioperative Management of High Risk Patients: Going Beyond "Avoid Hypoxia and Hypotension"
Long gone is the time when a preoperative medical consultation offered the pseudo sage and rather unhelpful advice to "avoid hypoxia and hypotension." Perioperative medicine is evolving as a distinct clinical science. For patients with chronic comorbid conditions who are designated to have surgery (increasing in numbers each year with an aging population) their medical management is now better understood to include unique and often nuanced medical care. A key observation in this regard has been perioperative management of blood pressure (BP) Operations performed among patients with hypertensive disease carry increased risk of adverse postsurgical outcomes compared with surgery for patients without hypertensive disease. Severe hypertension (for instance, systolic BP >180 mm Hg or pulse pressure >100 mm Hg) predisposes patients to wide swings in intraoperative BP and consequent cardiac arrhythmias and myocardial, renal, and cerebral ischemia; as many as 10% of these patients are at high risk for the development of cardiovascular complications. Low preoperative BP has also been associated with adverse postsurgical outcomes.1 5 In part for this reason, monitoring of intraoperative BP, more than any other single parameter, is a core tenet of intraoperative vigilance by anesthesiologists, and BP management remains an important focus of intraoperative clinical care. Despite the ubiquity of this tenet, the goals of intraoperative BP management are not well supported by a robust evidence base. The management goals for perioperative (a term that includes intraoperative) BP are different from nonsurgical BP management. Perioperative BP changes are due to multiple factors, including rapid intravenous volume shifts, changes in sympathetic tone due to onset and offset of anesthetic agents, surgical stimulation, autonomic stress responses, and pain. Anesthetic drugs with variable pharmacokinetic properties affect cardiovascular function in a dose dependent manner by reducing central sympathetic tone, attenuating baroreflex activity, inhibiting end organ BP autoregulatory function, and having direct effects on the heart and peripheral vasculature. Opioids affect cardiovascular function by attenuation of sympathetic afferent and efferent activity, direct central or peripheral vagal stimulation, and direct and indirect effects on the myocardium and vascular smooth muscle. Indeed, decreased or elevated BP values in the perioperative setting often lead to situations that require active tolerance (a proactive decision not to treat) or, conversely, acute management in what would otherwise be perceived as an unacceptable or acceptable nonsurgical situation, respectively. It is therefore generally accepted that optimal perioperative BP should be defined differently than commonly referenced in an ambulatory environment due to unique clinicalphysiological considerations in a setting of anesthesia and surgery. Whereas data from the ambulatory setting has challenged traditional optimal BP management standards,6 it is also recognized that in the surgical setting a relationship between BP and outcomes is complex. Several components contribute to this complexity. What defines "appropriate" BP targets and to what degree these targets are applicable across patient types or surgical interventions have only recently been explored,7 14 with some retrospective studies capitalizing on electronic health record data acquisition to enable large scale analysis. Given the paucity of data linking perioperative BP management and outcomes, BP management decisions are usually based on clinician knowledge, experience, and beliefs and are subject to regional and geographic practice patterns. Even though it may seem intuitive that defining perioperative goals for BP target control should depend on patient factors such as the presence of preexisting hypertensive disease, the specific acute care situation that is being managed, the vulnerable end organ for each patient in each instance, and treatment safety and effectiveness, there are few to no data to support any specific practice. A rational, scientific, data based intraoperative BP management guidance strategy is needed. Understanding what constitutes a safe BP during the perioperative period is a complex medical decision dependent on several factors, including patient physiology and procedural need; as such, defining a "best way" to achieve a target BP during the perioperative period is challenging. The Intraoperative Norepinephrine to Control Arterial Pressure (INPRESS) study reported by Futier and colleagues in this issue of JAMA15 prospectively compared 2 intraoperative BP management strategies in a high risk noncardiac surgical population. In this multicenter randomized clinical trial conducted in 9 French university and nonuniversity hospitals, adult patients (n 298) at increased risk of postoperative complications who were undergoing major surgery (predominantly abdominal operations) under general anesthesia were randomly assigned to receive an individualized management strategy aimed at achieving a systolic BP (SBP) within 10% of the reference value (ie, the patient's resting SBP) or a standard management strategy of treating SBP values less than 80 mm Hg or lower than 40% from the reference value during and for 4 hours following surgery. The primary outcome event, a composite of systemic Related article Opinion
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