ERECTOR SPINAE PLANE BLOCK FOR MINIMALLY INVASIVE MITRAL VALVE SURGERY HAS NO IMPACT ON POSTOPERATIVE OUTCOMES: A DOUBLE-BLIND, PROSPECTIVE RANDOMIZED PLACEBO-CONTROLLED TRIAL

Abstract

<h3>Objective</h3> Compared to traditional sternotomy, minimally invasive mitral valve surgery (MIMVS) using video-assisted thoracoscopy has been shown to result in an increased incidence of moderate to severe acute postoperative pain.1 The Erector Spinae Plane (ESP) block, a novel fascial plane block, may be an useful and safe option for postoperative analgesia in MIMVS.2 As randomized trials in this field are sparse, we hypothesized that an intermittent ESP block with ropivacaine 0.5% (intervention group) compared to normal saline 0.9% (control group) is effective in reducing postoperative pain after MIVMS.3 <h3>Design & Methods</h3> PPThis single center, double-blind, prospective, randomized, placebo-controlled trial was approved by the local Ethics Committee (S62638 June 4th 2019, EudraCT 2019-001125-27). The trial was supported by the EACTA Research Grant 2020. Primary endpoint was postoperative 24h morphine consumption. Based on pilot data and to have an 80% power to show a 25% reduction in 24h morphine consumption in the intervention-group compared to the control-group, 64 patients had to be randomized (1:1 ratio). A pre-planned sample size recalculation was performed after inclusion of 32 patients. Multiple secondary endpoints were evaluated up to 30-days postoperatively including postoperative pain scores, midaxillary sensory block, rescue treatments for pain and hospital length of stay.3 <h3>Results</h3> Sample size recalculation revealed the need to recruit 4 additional patients in each group. 72 patients were randomized between July 2nd 2019 and November 4th 2021. Regarding our primary outcome, 2 patients in the intervention-group could not be assessed due to reintubation and ischemic cerebral event. In the control-group, we observed 2 epileptic seizures requiring unblinding of the randomization to start appropriate treatment. There were no differences in baseline or procedural characteristics. The median (IQR) 24h morphine consumption was not different between the intervention- and control-group: 41mg [30;55] vs 37mg [29;50], p=0.70, respectively (Table 1). Mean numerical rating scale values for pain showed no significant differences between groups (Figure 1). The number of morphine boli requested each hour by the patient, sensory block, rescue treatments for pain and hospital length of stay were comparable (Figure 2 & Table 1). <h3>Conclusion</h3> In the current placebo-controlled trial following MIMVS, we were unable to demonstrate any benefit from the addition of an intermittent ESP-block to a standard multimodal analgesia regimen.