Microvascular reactivity monitored with near-infrared spectroscopy is impaired after induction of anaesthesia in cardiac surgery patients: An observational study.

BACKGROUND: Induction of anaesthesia causes significant macrohaemodynamic changes, but little is known about its effects on the microcirculation. However, alterations in microvascular perfusion are known to be associated with impaired tissue oxygenation and organ dysfunction. Microvascular reactivity can be assessed with vascular occlusion testing, which evaluates the response of tissue oxygen saturation to transient ischaemia and reperfusion. OBJECTIVE: The aim of the current study was to evaluate the effects of an opioid-based anaesthesia induction on microvascular reactivity. We hypothesised that despite minimal blood pressure changes, microvascular function would be impaired. DESIGN: Prospective, observational study. SETTING: Single-centre, tertiary university teaching hospital, Belgium. PATIENTS: Thirty-five adult patients scheduled for elective coronary artery bypass grafting surgery. INTERVENTION: Microvascular reactivity was assessed before and 30 min after anaesthesia induction by means of vascular occlusion testing and near-infrared spectroscopy. MAIN OUTCOME MEASURES: Tissue oxygen saturations, desaturation rate, recovery time (time from release of cuff to the maximum value) and rate of recovery were determined. RESULTS: Data are expressed as median (minimum to maximum). Tissue oxygen saturation was higher after induction of anaesthesia [70 (54 to 78) vs. 73 (55 to 94)%, P = 0.015]. Oxygen consumption decreased after induction, appreciable by the higher minimum tissue oxygen saturation [45 (29 to 69) vs. 53 (28 to 81)%, P < 0.001] and the slower desaturation rate [11 (4 to 18) vs. 9 (5 to 16)% min, P < 0.001]. After induction of anaesthesia, recovery times were longer [40 (20 to 120) vs. 48 (24 to 356) s, P = 0.004] and the rate of recovery was lower [114 (12 to 497) vs. 80 (3 to 271)% min, P < 0.001]. CONCLUSION: After induction of anaesthesia, oxygen consumption was decreased. The longer recovery times and slower rates of recovery indicate impaired microvascular reactivity after induction of anaesthesia. TRIAL REGISTRATION: The research project was registered at ClinicalTrials.gov (NCT02034682).

The patient with hypertension undergoing surgery.

PURPOSE OF REVIEW: General recommendations for the perioperative management of patients with hypertensive disease have not evolved much over the past 20 years, yet new pathophysiological concepts have emerged and new monitoring techniques are available today. In this review, we will discuss their significance and potential role in the modern perioperative care of hypertensive patients. RECENT FINDINGS: For hypertensive patients, total cardiovascular risk rather than blood pressure (BP) alone should determine the preoperative strategy. Except for grade 3 hypertension, surgery should not be deferred on the basis of an elevated BP in the preoperative assessment.New data suggest that even brief hypotensive episodes during surgery may have significant impact on outcome. Isolated systolic hypertension is the predominant phenotype in elderly patients who may be particularly vulnerable to hypoperfusion in the perioperative setting.New monitoring techniques such as echocardiography and near-infrared spectroscopy may provide crucial information to optimize intraoperative control of BP based on an individual patient's pathophysiology. SUMMARY: Hypertension is highly prevalent in patients presenting for surgery yet its impact on surgical outcome is still debated. Guidelines on risk stratification and perioperative hemodynamic management of patients with hypertensive disease remain sparse and cannot rely much on solid new evidence. Target organ damage associated with hypertensive disease rather than high BP per se appears to determine perioperative risk. In the absence of new data, an individualized and pathophysiology-based approach to control BP may be the best option to guide these patients through the perioperative period.