Association between mean arterial pressure and sublingual microcirculation during major non‐cardiac surgery: Post hoc analysis of a prospective cohort

Abstract

Objective To test the hypothesis that there is an association between mean arterial pressure (MAP) and sublingual perfusion during major surgery, and perhaps an identifiable harm threshold. Methods This post hoc analysis of a prospective cohort included patients who had elective major non‐cardiac surgery with a duration of ≥2 h under general anesthesia. We assessed sublingual microcirculation every 30 min using SDF+ imaging and determined the De Backer score, Consensus Proportion of Perfused Vessels (Consensus PPV), and the Consensus PPV (small). Our primary outcome was the relationship between MAP and sublingual perfusion which was evaluated with linear mixed effects modeling. Results A total of 100 patients were included, with MAP ranging between 65 mmHg and 120 mmHg during anesthesia and surgery. Over a range of intraoperative MAPs between 65 and 120 mmHg, there were no meaningful associations between blood pressure and various measures of sublingual perfusion. There were also no meaningful changes in microcirculatory flow over 4.5 h of surgery. Conclusions In patients having elective major non‐cardiac surgery with general anesthesia, sublingual microcirculation is well maintained when MAP ranges between 65 and 120 mmHg. It remains possible that sublingual perfusion will be a useful marker of tissue perfusion when MAP is lower than 65 mmHg.

The Relation of Calculated Plasma Volume Status to Sublingual Microcirculatory Blood Flow and Organ Injury

“…Although the distribution of microvascular blood flow is highly heterogeneous and its changes are generally thought to be multifactorial [1,9,10], our findings support a recently published risk-adapted fluid strategy recommending a moderately liberal approach aiming at a positive fluid balance of 1-2 L at the end of surgery [23]. A moderately positive fluid balance could improve the postoperative microcirculatory flow and tissue perfusion, especially when the MAP is maintained between 65 and 120 mmHg [8,11]. However, occult hypovolemia may occur in up to 60% of patients undergoing major surgery [29], and more research is needed to identify the optimal perioperative cPVS target.…”

“…Before study measurements, we confirmed that the transducers were correctly leveled and zeroed. We also confirmed the system's dynamic response, and artifacts were assessed and managed as previously described [11].…”

“…Before analysis, all sublingual perfusion videos were evaluated by two experienced raters blinded to all patient data, according to a modified microcirculation image quality score (MIQS) [12]. The best three videos from each recording were analyzed offline by a blinded investigator using the AVA4.3C Research Software (Microvision Medical, Amsterdam, the Netherlands) [11,13,14]. We analyzed the De Backer score as the density score, and the Consensus Proportion of Perfused Vessels (Consensus PPV), and Consensus PPV (small) as flow scores.…”

“…In addition, dynamic assessment methods may not be available, while static filling methods may lead to erroneous assessments. Although some studies showed that the microcirculatory flow may improve after fluid administration and stroke volume increase [32,33], recent evidence suggests that microvascular perfusion is maintained when the MAP ranges between 65 and 120 mmHg [11]. Consequently, circulatory volume imbalances may potentially result in organ injury even in patients with adequate microcirculation, making the estimation of fluid losses or overload challenging [34][35][36][37].…”