Study evaluates Pharmacokinetics of Ropivacaine in Continuous Thoracic Paravertebral Blockade

While thoracic paravertebral blockade (TPVB) is utilized in thoracic surgery to achieve adequate postoperative pain relief, it often necessitates high doses of anesthetics and may lead to the manifestation of local anesthetic systemic toxicity (LAST). Recent study investigated the pharmacokinetics of ropivacaine after continuous thoracic paravertebral blockade (TPVB) and the risk of local anesthetic systemic toxicity (LAST) in patients undergoing open thoracotomy.

The study involved 18 patients who underwent ultrasound-guided continuous TPVB. A 25-ml single bolus injection of ropivacaine 0.5% was administered through a thoracic paravertebral catheter, followed by a 14 ml/h continuous infusion of ropivacaine 0.2% starting at the end of surgery. Ropivacaine concentrations were measured in arterial and venous blood samples using high-performance liquid chromatography.

The best pharmacokinetic model was a one-compartment disposition model with an additional pre-absorption compartment corresponding to the thoracic paravertebral space. Gender had a significant effect on ropivacaine clearance, with females displaying lower elimination than males. Some patients had ropivacaine concentrations above the toxic threshold, but none displayed evidence of LAST. The continuous thoracic paravertebral nerve blocks provided adequate postoperative analgesia.

The study shows that ropivacaine doses at the upper end of clinical use (800 mg/d) did not cause LAST and provided adequate postoperative pain control. Pharmacokinetic models were developed, and the effect of gender on ropivacaine clearance was identified. These findings contribute to a better understanding of ropivacaine pharmacokinetics after continuous thoracic paravertebral blockade and can help guide the safe and effective use of this technique in patients undergoing thoracic surgery.

Key Points

Here are the 3 key points from the research paper:

1. The study investigated the pharmacokinetics of ropivacaine after continuous thoracic paravertebral blockade (TPVB) and the risk of local anesthetic systemic toxicity (LAST) in patients undergoing open thoracotomy. 18 patients received a single bolus injection of ropivacaine 0.5% followed by a continuous infusion of ropivacaine 0.2%, and ropivacaine concentrations were measured in arterial and venous blood samples.

2. The best pharmacokinetic model was a one-compartment disposition model with an additional pre-absorption compartment corresponding to the thoracic paravertebral space. Gender had a significant effect on ropivacaine clearance, with females displaying lower elimination than males. Some patients had ropivacaine concentrations above the toxic threshold, but none displayed evidence of LAST.

3. The continuous thoracic paravertebral nerve blocks provided adequate postoperative analgesia, and the study shows that ropivacaine doses at the upper end of clinical use (800 mg/d) did not cause LAST. The findings contribute to a better understanding of ropivacaine pharmacokinetics after continuous thoracic paravertebral blockade and can help guide the safe and effective use of this technique in patients undergoing thoracic surgery.

Reference –

Matsota, Paraskevi, Karalis, Vangelis1, Saranteas, Theodosios, Kiospe, Fay1, Markantonis, Sophia Liberty1. Ropivacaine pharmacokinetics in the arterial and venous pools after ultrasound-guided continuous thoracic paravertebral nerve block. Journal of Anaesthesiology Clinical Pharmacology 40(2):p 283-292, Apr–Jun 2024. | DOI: 10.4103/joacp.joacp_353_22.