Ropivacaine plasma levels following local infiltration analgesia for primary total hip arthroplasty

Serum concentrations of local anesthetics after unilateral interpectoral-pectoserratus plane block in breast cancer surgery: a pharmacokinetic study

INTRODUCTION

The ultrasound-guided interpectoral-pectoserratus plane block is a fascial plane block for superficial surgery of the anterolateral chest wall. This technique involves injecting a relatively large volume of local anesthetics (typically 30 mL of 0.25%-0.50%, ie, 75-150 mg ropivacaine) underneath the major and minor pectoral muscles of the anterior thoracic wall. There is a potential risk of toxic serum concentrations of local anesthetics due to systemic absorption.

METHODS

22 patients scheduled for elective unilateral breast cancer surgery were included in this study. All surgery was performed with general anesthesia and an ultrasound-guided interpectoral-pectoserratus plane block with 2.5 mg/kg ropivacaine. Ten venous blood samples were collected at 0 (two samples) 10, 20, 30, 45, 60, 90 and 120 min and at 4 hours after performing the block. Free and total ropivacaine levels were measured at each time point. Albumin and alpha-1-acid-glycoprotein were measured to monitor shifts between the free and bound fraction of ropivacaine.

RESULTS

Samples of 20 patients were analyzed. The mean dose of ropivacaine was 172.8 (22.5) mg. In 50% of the patients, the potentially toxic threshold of 0.15 µg/mL free ropivacaine concentration was exceeded. Mean peak serum concentration occurred at 20 min postinjection.

CONCLUSIONS

This pharmacokinetic study demonstrated that a 2.5 mg/kg ropivacaine interpectoral-pectoserratus plane block may result in exceeding the threshold for local anesthetic systemic toxicity.

Validation according to European and American regulatory agencies guidelines of an LC-MS/MS method for the quantification of free and total ropivacaine in human plasma

Background

Ropivacaine is a widely used local anaesthetic drug, highly bound to plasma proteins with a free plasma fraction of about 5%. Therefore, the monitoring of free drug concentration is most relevant to perform pharmacokinetic studies and to understand the drug pharmacokinetic/pharmacodynamic (PK/PD) relationship.

Methods

A high-sensitivity liquid chromatography-tandem mass spectrometry (LC-MS/MS) method using reverse-phase LC and electrospray ionisation mass spectrometry with multiple reaction monitoring (MRM) is described for the quantitation of both free and total ropivacaine in human plasma. Ropivacaine-d7 was used as an internal standard (IS).

Results

The method was validated in the range 0.5–3000 ng/mL, with five levels of QC samples and according to the European Medicine Agency and Food and Drug Administration guidelines. The performance of the method was excellent with a precision in the range 6.2%–14.7%, an accuracy between 93.6% and 113.7% and a coefficient of variation (CV) of the IS-normalised matrix factor below 15%. This suitability of the method for the quantification of free and total ropivacaine in clinical samples was demonstrated with the analysis of samples from patients undergoing knee arthroplasty and receiving a local ropivacaine infiltration.

Conclusions

A method was developed and validated for the quantification of free and total ropivacaine in human plasma and was shown suitable for the analysis of clinical samples.

Local infiltration analgesia: a 2-year follow-up of patients undergoing total hip arthroplasty

Purpose

Local infiltration analgesia (LIA) is commonly used for postoperative pain management following total hip arthroplasty (THA). However, the long-term effects of the component drugs are unclear. The aim of our study was to investigate functional outcome, quality of life, chronic post-surgical pain, and adverse events in patients within 2 years of undergoing THA.

Methods

The study was a secondary analysis of data from a previous larger study. Eighty patients were randomized to receive either intrathecal morphine (Group ITM) or local infiltration analgesia (Group LIA) for pain management in a double-blind study. The parameters measured were patient-assessed functional outcome [using the Hip dysfunction and Osteo-arthritis Outcome Score (HOOS) questionnaire], health-related quality of life [using the European Quality of Life–5 dimensions (EQ-5D) questionnaire and the 36-Item Short Form Health Survey (SF-36) score], and pain using the numeric rating score (NRS), with persistent post-surgical pain having a NRS of > 3 or a HOOS pain sub-score of > 30. All complications and adverse events were investigated during the first 2 years after primary surgery.

Results

Pain intensity and rescue analgesic consumption were similar between the groups after hospital discharge. No differences were found in HOOS or SF-36 score between the groups up to 6 months after surgery. A significant group × time interaction was seen in the EQ 5D form in favor of the LIA group. No between-group difference in persistent post-surgical pain was found at 3 or 6 months, or in adverse events up to 2 years after surgery.

Conclusion

Analysis of functional outcome, quality of life, and post-discharge surgical pain did not reveal significant differences between patients receiving LIA and those receiving ITM. LIA was found to be a safe technique for THA during the long-term follow-up. However, it should be noted that these conclusions are based on a limited number of patients.

Randomized clinical study on the analgesic effect of local infiltration versus spinal block for hemorrhoidectomy

BACKGROUND AND OBJECTIVES:

Postoperative analgesia and early recovery are important for hospital discharge. The primary objective of this study was to compare the analgesic effectiveness of perianal infiltration and subarachnoid anesthesia for hemorrhoidectomy. The secondary objective was to compare time to discharge, adverse effects and complications.

DESIGN AND SETTING:

Randomized, prospective and comparative study at Dr. Mário Gatti Hospital.

METHODS:

Forty patients aged 18-60, in American Society of Anesthesiologists physical status category 1 or 2, were included. The local group (LG) received local infiltration (0.75% ropivacaine) under general anesthesia; the spinal group (SG) received subarachnoid block (2 ml of 0.5% bupivacaine). Analgesic supplementation consisted of fentanyl for LG and lidocaine for SG. Postoperative pain intensity, sphincter relaxation, lower-limb strength, time to discharge, analgesic dose over one week and adverse effects were assessed.

RESULTS:

Eleven LG patients (52.4%) required supplementation, but no SG patients. Pain intensity was higher for LG up to 120 min, but there were no differences at 150 or 180 min. There were no differences in the need for paracetamol or tramadol. Times to first analgesic supplementation and hospital discharge were longer for SG. The adverse effects were nausea, dizziness and urinary retention.

CONCLUSIONS:

Pain intensity was higher in LG than in SG over the first 2 h, but without differences after 150 and 180 min. Time to first supplementation was shorter in LG. There were no differences in doses of paracetamol and tramadol, or in adverse effects.

REGISTRATION:

ClinicalTrials.gov NCT02839538.

Regional analgesia techniques for total knee replacement

PURPOSE OF REVIEW

Pain following total knee arthroplasty is a challenging task for healthcare providers. Concurrently, fast recovery and early ambulation are required to regain function and to prevent postoperative complications. Ideal postoperative analgesia provides sufficient pain relief with minimal opioid consumption and preservation of motor strength. Regional analgesia techniques are broadly used to answer these expectations. Femoral nerve blocks are performed frequently but have suggested disadvantages, such as motor weakness. The use of lumbar epidurals is questioned because of the risk of epidural hematoma. Relatively new techniques, such as local infiltration analgesia or adductor canal blocks, are increasingly discussed. The present review discusses new findings and weight between known benefits and risks of all of these techniques for total knee arthroplasty.

RECENT FINDINGS

Femoral nerve blocks are the gold standard for total knee arthroplasty. The standard use of additional sciatic nerve blocks remains controversial. Lumbar epidurals possess an unfavourable risk/benefit ratio because of increased rate of epidural hematoma in orthopaedic patients and should be reserved for lower limb amputation; peripheral regional techniques provide comparable pain control, greater satisfaction and less risk than epidural analgesia. Although motor weakness might be greater with femoral nerve blocks compared with no regional analgesia, new data point towards a similar risk of falls after total knee arthroplasty with or without peripheral nerve blocks. Local infiltration analgesia and adductor canal blockade are promising recent techniques to gain adequate pain control with a minimum of undesired side-effects.

SUMMARY

Femoral nerve blocks are still the gold standard for an effective analgesia approach in knee arthroplasty and should be supplemented (if needed) by oral opioids. An additional sciatic nerve blockade is still controversial and should be an individual decision. Large-scale studies are needed to reinforce the promising results of newer regional techniques, such as local infiltration analgesia and adductor canal block.

Thoracic Epidural analgesia versus Rectus Sheath Catheters for open midline incisions in major abdominal surgery within an enhanced recovery programme (TERSC): study protocol for a randomised controlled trial

BACKGROUND

Thoracic epidural analgesia (TEA) is recommended for post-operative pain relief in patients undergoing major abdominal surgery via a midline incision. However, the effectiveness of TEA is variable with high failure rates reported post-operatively. Common side effects such as low blood pressure and motor block can reduce mobility and hinder recovery, and a number of rare but serious complications can also occur following their use.Rectus sheath catheters (RSC) may provide a novel alternative approach to somatic analgesia without the associated adverse effects of TEA. The aim of this study is to compare the efficacy of both techniques in terms of pain relief, patient experience, post-operative functional recovery, safety and cost-effectiveness.

METHODS/DESIGN

This is a single-centre randomised controlled non-blinded trial, which also includes a nested qualitative study. Over a two-year period, 132 patients undergoing major abdominal surgery via a midline incision will be randomised to receive either TEA or RSC for post-operative analgesia. The primary outcome measures pain scores on moving from a supine to a sitting position at 24 hours post wound closure, and the patient experience between groups evaluated through in-depth interviews. Secondary outcomes include pain scores at rest and on movement at other time points, opiate consumption, functional recovery, morbidity and cost-effectiveness.

DISCUSSION

This will be the first randomised controlled trial comparing thoracic epidurals to ultrasound-guided rectus sheath catheters in adults undergoing elective midline laparotomy. The standardised care provided by an Enhanced Recovery Programme makes this a comparison between two complex pain packages and not simply two analgesic techniques, in order to ascertain if RSC is a viable alternative to TEA.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN81223298 (16 January 2014).