Tissue oxygen saturation changes and postoperative complications in cardiac surgery: a prospective observational study

Abstract

BackgroundCardiac surgery with extracorporeal circulation (ECC) can induce microvascular dysfunction and tissue hypoperfusion. We hypothesized that the alterations in near-infrared spectroscopy (NIRS)-derived parameters would be associated with post-operative complications in cardiac surgery patients.MethodsProspective observational study performed at two University Hospitals. Ninety patients undergoing cardiac surgery with ECC were enrolled. The NIRS sensor was applied on the thenar eminence. A vascular occlusion test (VOT, 3-min ischemia) was performed at baseline (t0), at Intensive Care Unit (ICU) admission (t1), 3 (t2) and 6 (t3) hours later. Baseline tissue oxygen saturation (StO2), oxygen extraction rate and microvascular reactivity indices were calculated.ResultsIn the first hours after cardiac surgery, StO2 tended to increase (86% [80–89] at T3 versus 82% [79–86] at T0, p = ns), while both tissue oxygen extraction and microvascular reactivity tended to decrease, as indicated by increasing occlusion slope (− 8.1%/min [− 11.2 to − 7] at T3 versus − 11.2%/min [− 13.9 to − 7.9] at T0, p = ns) and decreasing recovery slope (1.9%/sec [1.1–2.9] at T3 versus 3.1%/sec [2.3–3.9] at T0, p = ns). No substantial differences were found in NIRS-derived variables and their changes over time between patients with complications and those without complications.ConclusionsPeripheral tissue oxygen extraction and microvascular reactivity were reduced during the first hours after cardiac surgery. NIRS-derived parameters were not able to predict complications in this population of cardiac surgery patients.

Microvascular reactivity as a predictor of major adverse events in patients with on-pump cardiac surgery

“…Other studies have performed VOT at the end of surgery or after ICU admissions [19][20][21]. The reason for the inconsistent results might be the timing at which the VOT was performed.…”

“…Therefore, several studies have investigated whether microcirculatory shock in cardiac surgeries correlates with the postoperative outcomes using a vascular occlusion test (VOT) with near-infrared spectroscopy (NIRS) [18][19][20][21]. Some studies have found that the recovery slope of VOT (representing the microvascular reactivity) in the intensive care unit (ICU) post-surgery was associated with postoperative outcomes [19,20].…”

The use of a vascular occlusion test combined with near-infrared spectroscopy in perioperative care: a systematic review

“…However one study found no correlation between intra-or postoperative RA values and ICU LOS [36]. The AUC-H before surgery was lower in patients with postoperative cardiac complications compared to those having either non-cardiac postoperative complications or no postoperative complications [39].…”

“…The StO 2 increased in patients with postoperative atrial fibrillation after returning to sinus rhythm [28]. In one study the DA decreased at ICU admission compared to baseline values obtained before surgery in all patients, but this only reached significance in the patient group without postoperative complications [39]. However, another study showed that low DA values (thenar eminence or forearm) at ICU admission and after 6 h of ICU stay were independently associated with a prolonged hospital LOS [11].…”

“…However, another study showed that low DA values (thenar eminence or forearm) at ICU admission and after 6 h of ICU stay were independently associated with a prolonged hospital LOS [11]. Five studies found that a decreased RA in the postoperative phase was associated with complications [39,40], postoperative atrial fibrillation [28], increased chest tube output [41], prolonged mechanical ventilation, and prolonged ICU LOS [11]. However one study found no correlation between intra-or postoperative RA values and ICU LOS [36].…”