Effectiveness of wound infusion of 0.2% ropivacaine by patient control analgesia pump after minithoracotomy aortic valve replacement: a randomized, double-blind, placebo-controlled trial

BACKGROUND: Local anesthetic wound infusion has become an invaluable technique in multimodal analgesia. The effectiveness of wound infusion of 0.2% ropivacaine delivered by patient controlled analgesia (PCA) pump has not been evaluated in minimally invasive cardiac surgery. We tested the hypothesis that 0.2% ropivacaine wound infusion by PCA pump reduces the cumulative dose of opioid needed in the first 48 h after minithoracothomy aortic valve replacement (AVR). METHODS: In this prospective, randomized, double-blind, placebo-controlled study, 70 adult patients (31 female and 39 male) were analyzed. Patients were randomized to receive 0.2% ropivacaine or 0.9% saline wound infusion by PCA pump for 48 h postoperatively. PCA pump was programmed at 5 ml h(− 1) continuously and 5 ml of bolus with 60 min lockout. Pain levels were assessed and recorded hourly by Numeric Rating Scale (NRS). If NRS score was higher than three the patient was administered 3 mg of opioid piritramide repeated and titrated as needed until pain relief was achieved. The primary outcome was the cumulative dose of the opioid piritramide in the first 48 h after surgery. Secondary outcomes were frequency of NRS scores higher than three, patient’s satisfaction with pain relief, hospital length of stay, side effects related to the local anesthetic and complications related to the wound catheter. RESULTS: The cumulative dose of the opioid piritramide in the first 48 h after minithoracotomy AVR was significantly lower (p < 0.001) in the ropivacaine (R) group median 3 mg (IQR 6 mg) vs. 9 mg (IQR 9 mg). The number of episodes of pain where NRS score was greater than three median 2 (IQR 2), vs 3 (IQR 3), (p = 0.002) in the first 48 h after surgery were significantly lower in the ropivacaine group, compared to control. Patient satisfaction with pain relief in our study was high. There were no wound infections and no side-effects from the local anesthetic. CONCLUSIONS: Wound infusion of local anesthetic by PCA pump significantly reduced opioid dose needed and improves pain control postoperatively. We have also shown that it is a feasible method of analgesia and it should be considered in the multimodal pain control strategy following minimally invasive cardiac surgery. TRIAL REGISTRATION: ClinicalTrials.gov NCT03079830, date of registration: March 15, 2017. Retrospecitvely registered.