Potentially toxic concentrations in blood of total ropivacaine after bilateral transversus abdominis plane blocks; a pharmacokinetic study

Quadratus lumborum block vs. transversus abdominis plane block for postoperative pain control in patients with nephrectomy: A systematic review and network meta-analysis

STUDY OBJECTIVE

This systematic review and network meta-analysis aimed to compare the analgesic efficacy of transversus abdominis plane block (TAPB) and quadratus lumborum block (QLB) on nephrectomy.

DESIGN

Systematic review and network meta-analysis.

PATIENTS

Patients undergoing nephrectomy.

INTERVENTIONS

TAPB and QLB for postoperative analgesia.

MEASUREMENTS

The primary outcome was 24 h morphine-equivalent consumptions after surgery. Secondary outcomes included postoperative pain scores, postoperative opioid consumption, postoperative rescue analgesia, postoperative nausea and vomiting (PONV), length of hospital stay after surgery, and patient satisfaction.

MAIN RESULTS

Fourteen studies involving 883 patients were included. Seven studies compared TAPB to control, six studies compared QLB to control, and one study compared TAPB to QLB. For direct meta-analysis of the post-surgical 24 h morphine-equivalent consumption, QLB was lower than control (mean difference [95%CI]: -18.16 [-28.96, -7.37]; I2 = 88%; p = 0.001), while there was no difference between TAPB and control (mean difference [95%CI]: -8.34 [-17.84, 1.17]; I2 = 88%; p = 0.09). Network meta-analysis showed similar findings that QLB was ranked as the best anesthetic technique for reducing postoperative 24 h opioid consumption (p-score = 0.854). Moreover, in direct meta-analysis, as compared to control, the time of first postoperative rescue analgesia was prolonged after QLB (mean difference [95%CI]: 165.00 [128.99, 201.01]; p < 0.00001), but not TAPB (mean difference [95%CI]: 296.82 [-91.92, 685.55]; p = 0.13). Meanwhile, QLB can effectively reduce opioid usages at intraoperative period, as well as at postoperative 6 h and 48 h, while TAPB can only reduce opioid consumption at 6 h after surgery. As compared to control, both TAPB and QLB exhibited the reduction in PONV and pain scores at post-surgical some timepoints. Also, QLB (mean difference [95%CI]: -0.29 [-0.49, -0.08]; p = 0.006) but not TAPB (mean difference [95%CI]: 0.60 [-0.25, 1.45]; p = 0.17) exhibited the shorter postoperative length of hospital stay than control.

CONCLUSIONS

QLB is more likely to be effective in reducing postoperative opioid use than TAPB, whereas both of them are superior to control with regard to the reduction in postoperative pain intensity and PONV.

TRIAL REGISTRATION

PROSPERO identifier: CRD42022358464.

Serum Levels of Bupivacaine After Bilateral Ultrasound-Guided Deep Parasternal Intercostal Plane Block in Cardiac Surgery with Median Sternotomy

OBJECTIVE

To evaluate systemic levels of bupivacaine after bilateral ultrasound-guided deep parasternal intercostal plan (PIP) block in cardiac surgical patients undergoing median sternotomy.

DESIGN

Prospective, observational study SETTING: Single institution; academic university hospital PARTICIPANTS: Twenty-eight adult patients undergoing cardiac surgery with median sternotomy received a PIP block with 2.5 mg/kg bupivacaine with or without dexamethasone and dexmedetomidine.

MEASUREMENTS

Arterial blood samples were analyzed for total serum bupivacaine concentration at 5, 15, 30, 45, 60, 90, 120, and 150 minutes after placement of PIP. Local anesthetic volume, local anesthetic adjuncts, time to extubation, postoperative pain scores, and opioid consumption were recorded.

MAIN RESULTS

The mean peak bupivacaine concentration was 0.60 ± 0.62 µg/mL, and the mean time to maximum concentration (Tmax) was 16.92 ± 12.97 minutes. Two patients (7.1%) had a concentration >2.0 µg/mL within 15 minutes of block placement. The mean Tmax of bupivacaine was significantly greater in patients who did not receive additives compared to those patients who did (22.86 ± 14.77 minutes v 10.0 ± 5.22 minutes; p = .004). The times to extubation and postoperative pain were not improved with additives.

CONCLUSIONS

Bilateral PIP placed at the end of cardiac surgery resulted in low systemic bupivacaine levels. The inclusion of additives shortened Tmax without improving outcome.

Safety and feasibility of ultrasound-guided serratus anterior plane block and intercostal nerve block for management of post-sternotomy pain in pediatric cardiac patients: A prospective, randomized trial

BACKGROUND

Postoperative analgesia in the cardiothoracic ICU has traditionally relied on intravenous opioids. Thoracic nerve blocks are attractive alternatives for analgesia that reduce the requirement for opioids, but their safety and feasibility remain unclear.

METHODS

Sixty children were allocated randomly to three groups: group C received intravenous opioids alone, while group SAPB (deep serratus anterior plane block) and group ICNB (intercostal nerve block) received opioids combined with ultrasound-guided regional nerve blocks (0.2% ropivacaine 2.5 mg.kg-1) after patients were transferred to the ICU. The primary outcome was opioid requirement in the first 24 h after surgery. Other outcomes included the postoperative FLACC scale value, tracheal extubation time, and plasma ropivacaine concentrations after the block.

RESULTS

The mean [sd] cumulative dose of opioids administered postoperatively within 24 h in the SAPB (168.6 [76.9] μg.kg-1) and ICNB groups (170.0 [86.8] μg.kg-1) were significantly lower by nearly 53% than those in group C (359.3 [125.3] μg.kg-1, p = 0.000). The tracheal extubation time was shorter in the regional block groups than that in the control group, but the difference was not statistically significant (p = 0.177). The FLACC scale values at 0, 1, 3, 6, 12, and 24 h post-extubation were similar in the three groups. The mean peak plasma ropivacaine concentrations in the SAP and ICNB groups were 2.1 [0.8] and 1.8 [0.7] mg.L-1, respectively, 10 min post-block and then slowly decreased. No noticeable complications associated with regional anesthesia were observed.

CONCLUSIONS

Ultrasound-guided SAPB and ICNB provided safe and satisfactory early postoperative analgesia while reducing opioid consumption following sternotomy in pediatric patients.

CLINICAL TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiChiCTR2100046754.

Assessment of cardiotoxicity and plasma ropivacaine concentrations after serratus intercostal fascial plane block in an experimental model

Serratus intercostal fascial plane block (SIFPB) has emerged as an alternative to paravertebral block in breast surgery. It involves the administration of high volumes and doses of local anesthetics (LA) that can potentially reach toxic levels. Ropivacaine is widely used in thoraco-fascial blocks; however, there is no information on the plasma concentrations attained after SIPFB and whether they are associated with cardiotoxicity. Plasma concentrations of ropivacaine and its electrophysiological effects were evaluated in eight pigs after bilateral SIFPB with ropivacaine in doses of 3 mg/kg. Plasma concentrations, electrophysiological and hemodynamic parameters were measured sequentially for the following 180 min until the end of the study. The area under the curve, the maximum plasma concentration (C_max) and the time to reach C_max (t_max) were calculated. The median arterial ropivacaine concentration C_max was, 2.34 [1.40 to 3.74] µg/ml. The time to reach the highest concentration was 15 [10 to 20] min. Twenty-five percent of the animals had arterial concentrations above the lower limit concentration of ropivacaine for LA systemic toxicity (3.4 µg/ml). No alterations were observed in the electrophysiological or electrocardiographic parameters except for a prolongation of the QTc interval, from 489 ± 30 to 544 ± 44 ms (Δ11.38 ± 6%), P = 0.01. Hemodynamic parameters remained in the physiological range throughout the study. SIFPB with ropivacaine in doses of 3 mg/kg has reached potentially toxic levels, however, it has not been associated with adverse electrophysiological or hemodynamic effects.

Pharmacokinetics of Bupivacaine Following Administration by an Ultrasound-Guided Transversus Abdominis Plane Block in Cats Undergoing Ovariohysterectomy

Bupivacaine is commonly used for peripheral nerve block in veterinary medicine. This study described the pharmacokinetics of two doses of bupivacaine following administration by an ultrasound-guided transversus abdominis plane (TAP) block in cats undergoing ovariohysterectomy. Twelve healthy female adult cats were included in a randomized, prospective, blinded clinical trial. Anaesthetic protocol included acepromazine–buprenorphine–propofol–isoflurane–meloxicam. Each cat received 1 mL/kg of bupivacaine 0.2% or 0.25% (BUPI-2 and BUPI-2.5, respectively) via bilateral two-point TAP block before surgery (n = 6/group). Plasma concentrations of bupivacaine were detected using liquid chromatography-mass spectrometry. A one-compartment model and non-compartmental analysis described the pharmacokinetic parameters. Bupivacaine was detected up to 480 min (335 ± 76 in BUPI-2 and 485 ± 198 ng/mL in BUPI-2.5). For BUPI-2 and BUPI-2.5, maximum plasma concentrations were 1166 ± 511 and 1810 ± 536 ng/mL at 33 ± 14 and 47 ± 22 min, clearance was 5.3 ± 1.8 and 4.9 ± 1.5 mL/min/kg, and elimination half-life were 253 ± 55 and 217 ± 52 min, respectively. The two doses of bupivacaine via TAP block produced concentrations below toxic levels in cats. A dose of 2.5 mg/kg bupivacaine was safe to be administered using this block in healthy cats.

Transversus Abdominis Plane Block

In this narrative review article, the authors discuss the anatomy, nomenclature, history, approaches (posterior vs. lateral vs. subcostal), techniques, pharmacology, indications, and complications of transversus abdominis plane blocks, as well as possible alternative truncal blocks.

Despite the scarcity of evidence and contradictory findings, certain clinical suggestions can nonetheless be made. Overall transversus abdominis plane blocks appear most beneficial in the setting of open appendectomy (posterior or lateral approach). Lateral transversus abdominis plane blocks are not suggested for laparoscopic hysterectomy, laparoscopic appendectomy, or open prostatectomy. However, transversus abdominis plane blocks could serve as an analgesic option for Cesarean delivery (posterior or lateral approach) and open colorectal section (subcostal or lateral approach) if there exist contraindications to intrathecal morphine and thoracic epidural analgesia, respectively.

Future investigation is required to compare posterior and subcostal transversus abdominis plane blocks in clinical settings. Furthermore, posterior transversus abdominis plane blocks should be investigated for surgical interventions in which their lateral counterparts have proven not to be beneficial (e.g., laparoscopic hysterectomy/appendectomy, open prostatectomy). More importantly, because posterior transversus abdominis plane blocks can purportedly provide sympathetic blockade and visceral analgesia, they should be compared with thoracic epidural analgesia for open colorectal surgery. Finally, transversus abdominis plane blocks should be compared with newer truncal blocks (e.g., erector spinae plane and quadratus lumborum blocks) with well-designed and adequately powered trials.

Pharmacokinetics of ropivacaine in elderly patients receiving fascia iliaca compartment block

Local anesthetic of ropivacaine was demonstrated to reduce the postoperative pain in elderly patients. This study investigated the pharmacokinetics of ropivacaine at different concentrations in elderly patients subjected to fascia iliaca compartment block. Forty patients with femoral neck fracture at American Society of Anesthesiologists (ASA) I-II status, undergoing fascia iliaca compartment block (FICB) were randomized to two groups receiving 0.7 ml/kg of solution containing 0.375% ropivacaine (group L) or 0.5% ropivacaine (group H). Samples of venous blood were obtained immediately at different time points after FICB, and the total and free plasma concentrations of ropivacaine were measured by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). Statistical analysis was carried out using a pharmacokinetic calculation program (DAS 3.0). Visual Analogue Scale (VAS) scores were significantly decreased after FICB in both groups, and VAS score in group H was lower compared with group L. The total maximum plasma concentration (C_max) and the free C_max of ropivacaine in group H was higher than that in group L (P<0.05). The decrease of the total and free plasma concentration was operation time-dependent. Neither group showed signs of central nervous system and circulatory system toxicity. On the basis of these results, the concentrations of 0.375 and 0.5% ropivacaine held an efficiently analgesic effect for FICB, suggesting that ropivacaine can be employed in analgesic therapy. However, both concentrations have a potentially theoretical risk of local anesthetics poisoning, suggesting that a lower concentration may be a safer option for a single large volume of FICB.

Transversus abdominis plane block and intrathecal morphine use in cesarean section: a retrospective review

OBJECTIVES

Cesarean delivery is an extremely common surgical procedure practiced worldwide. It is an open abdominal surgery, and is associated with significant postoperative pain. One modality that helps alleviate this pain is the transversus abdominis plane (TAP) block. This analysis sought to evaluate postoperative pain when this block was used in conjunction with intrathecal morphine.

METHODS

A retrospective review was performed of 142 patients who underwent cesarean section at our institution. Of those, 43 patients had a TAP block performed. The primary outcome for this analysis was the time to first opioid administration following discharge from the operating room. Secondary outcomes included differences in postoperative pain scores, and overall opioid consumption.

RESULTS

The average time to first opioid use postoperatively decreased in the TAP group when compared with the No-TAP group, 23.3 versus 12.1, respectively (difference of 48.2% (95% CI 74.0% to 24.3%); p<0.001) and opioid consumption was significantly decreased within the first 24 hours following surgery from 4.55 intravenous morphine equivalents (IVME) to 2.67 IVME, respectively (difference of 107.1% (95% CI 145.1% to 69.2%); p=0.006). Visual analog pain scores were significantly decreased in the TAP group versus the No-TAP group up to 36 hours postoperatively.

CONCLUSIONS

TAP blocks performed in conjunction with intrathecal morphine may decrease opioid use in the first 24 hours and improve pain scores for at least 36 hours following cesarean section. Because of the favorable safety profile, TAP blocks may contribute meaningfully to multimodal anesthesia for cesarean sections.

Transversus Abdominal Plane Block in Children: Efficacy and Safety: A Randomized Clinical Study and Pharmacokinetic Profile

BACKGROUND

The transversus abdominis plane (TAP) block has become a common regional anesthesia technique for pain management in a wide variety of abdominal procedures. Evidence to support any particular local anesthetic regimen as well as pharmacokinetic and systemic toxicity risks of TAP block remain insufficiently studied in children. The aim of this study was to compare the analgesic effects and investigate pharmacokinetic profile of levobupivacaine after ultrasound-guided TAP block using a low volume/high concentration (LVHC) or a high volume/low concentration (HVLC) solution in children.

METHODS

This prospective randomized study included children scheduled for day-case inguinal surgery. Children were randomized to receive TAP block using 0.4 mg·kg levobupivacaine as either HVLC (0.2 mL·kg of 0.2% levobupivacaine) or LVHC (0.1 mL·kg of 0.4% levobupivacaine). The primary outcome was the number of children who required opioid rescue analgesia postoperatively. Pharmacokinetic profile study of levobupivacaine was also performed.

RESULTS

Seventy patients were equally randomized, and 65 were included in the final analysis. Seventy-one percent of patients did not require any postoperative opioid analgesia. The number of patients who received rescue analgesia was 12 (35%) in the LVHC group and 7 (23%) in the HVLC group (relative risk, 0.64; 95% confidence interval [CI], 0.29-1.42; P = .26). Mean pain scores (FLACC [faces, legs, activity, cry, and consolability]) at postanesthesia care unit discharge did not differ between LVHC and HVLC groups, respectively, 0.39 ± 0.86 and 1 ± 1.71 with mean group difference -0.60 (95% CI, -1.27 to 0.06; P = .08). The pharmacokinetic profile of levobupivacaine was comparable in the 2 groups: the mean total and free levobupivacaine peak concentrations were 379 ± 248 and 3.95 ± 3.16 ng·mL, respectively, occurring 22.5 ± 11 minutes after injection. The highest total and free levobupivacaine concentrations collected, respectively, 1360 and 15.1 ng·mL, remained far below theoretical toxic thresholds.

CONCLUSIONS

In children, quality of postoperative pain control provided by TAP block using levobupivacaine 0.4 mg·kg administered as either HVLC or LVHC did not differ and was associated with a very low risk of local anesthetic systemic toxicity.

Bilateral sternal infusion of ropivacaine and length of stay in ICU after cardiac surgery with increased respiratory risk: A randomised controlled trial

BACKGROUND

The continuous bilateral infusion of a local anaesthetic solution around the sternotomy wound (bilateral sternal) is an innovative technique for reducing pain after sternotomy.

OBJECTIVE

To assess the effects of the technique on the need for intensive care in cardiac patients at increased risk of respiratory complications.

DESIGN

Randomised, observer-blind controlled trial.

SETTING

Single centre, French University Hospital.

PATIENTS

In total, 120 adults scheduled for open-heart surgery, with one of the following conditions: age more than 75 years, BMI >30 kg m, chronic obstructive pulmonary disease, active smoking habit.

INTERVENTION

Either a bilateral sternal infusion of 0.2% ropivacaine (3 ml h through each catheter; 'intervention' group), or standardised care only ('control' group). Analgesia was provided with paracetamol and self-administered intravenous morphine.

MAIN OUTCOME MEASURES

The length of time to readiness for discharge from ICU, blindly assessed by a committee of experts.

RESULTS

No effect was found between groups for the primary outcome (P = 0.680, intention to treat); the median values were 42.4 and 37.7 h, respectively for the control and intervention groups (P = 0.873). Similar nonsignificant trends were noted for other postoperative delays. Significant effects favouring the intervention were noted for dynamic pain, patient satisfaction, occurrence of nausea and vomiting, occurrence of delirium or mental confusion and occurrence of pulmonary complications. In 12 patients, although no symptoms actually occurred, the total ropivacaine plasma level exceeded the lowest value for which neurological symptoms have been observed in healthy volunteers.

CONCLUSION

Because of a small size effect, and despite significant analgesic effects, this strategy failed to reduce the time spent in ICU.

TRIAL REGISTRATION

EudraCT (N°: 2012-005225-69); ClinicalTrials.gov (NCT01828788).

Plasma ropivacaine concentration after TAP block in a patient with cardiac and renal failure

We report a successful ultrasound-guided transversus abdominis plane (TAP) block as an analgesic option for minor abdominal surgery in a 66-year-old patient with cardiac, respiratory, and renal dysfunction caused by primary systemic amyloidosis. Bilateral TAP blocks with 120 mg (1.8 mg/kg) of ropivacaine provided sufficient intra- and postoperative analgesia for insertion of a continuous ambulatory peritoneal dialysis catheter. However, the plasma concentration of ropivacaine reached a maximum of 2.5 µg/mL at 15 minutes after the TAP block, a concentration that was potentially neurotoxic. Although apparent signs of local anesthetic systemic toxicity (LAST) such as convulsion or changes in an electrocardiogram were not observed, the patient became drowsy after the TAP block, which might be one of the mild symptoms of LAST. A TAP block by itself can thus be an anesthetic option for patients undergoing minor abdominal surgery. However, cardiac and renal dysfunction might influence the pharmacokinetics of a local anesthetic used, and attention should be paid to the possibility of LAST even with a low dose of a local anesthetic for patients with cardiac and renal failure.

Role of ultrasound guided transversus abdominis plane block as a component of multimodal analgesic regimen for lower segment caesarean section: a randomized double blind clinical study

Background

While opioids are the mainstay for post-operative analgesia after lower segment caesarean section, they are associated with various untoward effects. Ultrasound guided transversus abdominis plane (TAP) block has been postulated to provide effective analgesia for caesarean section. We evaluated the analgesic efficacy of this block for post caesarean analgesia in a randomised controlled trial.

Methods

One hundred thirty-nine mothers undergoing caesarean delivery were randomised to receive TAP block with either 20 ml 0.375% ropivacaine or 20 ml saline after obtaining informed consent. All the subjects received a standard spinal anaesthetic and diclofenac was administered for post-operative pain. Breakthrough pain was treated with tramadol. Post-operatively, all the subjects were assessed at 0, 2, 4, 6, 8, 10, 12, 18 & 24 h. The primary outcome was the time to first analgesic request. The secondary measures of outcome were pain, nausea, sedation, number of doses of tramadol administered and satisfaction with the pain management.

Results

The median (interquartile range) time to first analgesic request was prolonged in the TAP group compared to the control group (p < 0.0001); 11 h (8,12) and 4 h (2.5,6) respectively. The median (interquartile range) number of doses of tramadol consumed in the TAP group was 0 (0,1) compared to 2 (1,2) in the control group (p < 0.0001). At all points in the study, pain scores both at rest and on movement were lower in the study group (p < 0.0001). Maternal satisfaction with pain relief was also higher in the study group (p 0.0002). One subject in the TAP group had convulsions following injection of local anaesthetic solution. She was managed conservatively with supportive treatment following which she recovered.

Conclusion

TAP block reduces pain, prolongs the duration of analgesia and decreases supplemental opioid consumption when used for multimodal analgesia for pain relief after caesarean section. However, the risk of local anaesthetic systemic toxicity remains unknown with this block. Hence larger safety trials and measures to limit this complication need to be ascertained.

Trial registration

The trial was registered with the Clinical Trial Registry of India (CTRI/2017/03/008194) on 23/03/2017 (trial registered retrospectively).

Randomised Comparison of Three Types of Continuous Anterior Abdominal Wall Block after Midline Laparotomy for Gynaecological Oncology Surgery

Effective analgesia after midline laparotomy surgery is essential for enhanced recovery programs. We compared three types of continuous abdominal wall block for analgesia after midline laparotomy for gynaecological oncology surgery. We conducted a single-centre, double-blind randomised controlled trial. Ninety-four patients were randomised into three groups to receive two days of programmed intermittent boluses of ropivacaine (18 ml 0.5% ropivacaine every four hours) via either a transversus abdominis plane (TAP) catheter, posterior rectus sheath (PRS) catheter, or a subcutaneous (SC) catheter. All groups received patient-controlled analgesia with morphine, and regular paracetamol and non-steroidal anti-inflammatory medication. Measured outcomes included analgesic and antiemetic usage and visual analog scores for pain, nausea, vomiting, and satisfaction. Eighty-eight patients were analysed (29 SC, 29 PRS and 30 TAP). No differences in the primary outcome were found (median milligrams morphine usage on day two SC 28, PRS 25, TAP 21, P=0.371). There were differences in secondary outcomes. Compared with the SC group, the TAP group required less morphine in recovery (0 mg versus 6 mg, P=0.01) and reported less severe pain on day one (visual analog scores 36.3 mm versus 55 mm, P=0.04). The TAP group used fewer doses of tropisetron on day one compared with the PRS group (8 versus 21, P=0.016). Programmed intermittent boluses of ropivacaine delivered via PRS, TAP and SC catheters can be provided safely to patients undergoing midline laparotomy surgery. Initially TAP catheters appear superior, reducing early opioid and antiemetic requirements and severe pain, but these advantages are lost by day two.

Ultrasound anatomy of the transversus abdominis plane region in pregnant women before and after cesarean delivery

BACKGROUND

After cesarean delivery, analgesia is often incomplete and a multimodal approach to analgesia is necessary. Transverse abdominal plane (TAP) block has been advocated in this setting, yet no systematic description of the ultrasound anatomy in pregnant women exists in the literature. Therefore, we aimed to describe the sonographical features of relevant structures in pregnant women before and after elective cesarean.

METHODS

Sixty women at, or close to term scheduled for elective cesarean delivery underwent a standardized ultrasound examination before and after delivery. We assessed the visibility of the muscular layers and measured the distance from the skin to the layers of the abdominal wall muscles in the region for TAP block before and after cesarean section on both side.

RESULTS

The three muscular layers of the lateral abdominal wall (external oblique, internal oblique and transversus abdominis muscle) were visible in all examinations. Before cesarean section the median TAP distance was shorter: 2.9 cm (interquartile range 2.6-3.6) compared to 3.9 cm (3.1-4.5) after cesarean section (left side, p < 0.001). The external and internal oblique muscles were located closer to the skin surface before cesarean section. An increased body mass is associated with increased the TAP distance before and after birth (p < 0.001).

CONCLUSION

Relevant anatomical landmarks for a TAP block are sonographically well visible after cesarean delivery. Postoperatively, depth of the TAP as compared to before birth is increased significantly. Scanning the abdominal wall before CD will underestimate the target depth of the TAP after delivery. The obstetric anesthetist needs to be aware of these changes when planning a TAP block in the context of cesarean delivery.

Levobupivacaine absorption pharmacokinetics with and without epinephrine during TAP block: analysis of doses based on the associated risk of local anaesthetic toxicity

PURPOSE

Cases of local anaesthetic systemic toxicity (LAST) periodically occur following transversus abdominal plane (TAP) blocks. The aim of this study was to characterize levobupivacaine absorption pharmacokinetics, with and without epinephrine, and estimate the risk of LAST, based on a previously reported toxic threshold.

METHODS

Previously reported data from 11 volunteers receiving ultrasound-guided TAP blocks with and without epinephrine on two independent occasions were analysed. Serial venous concentrations were measured for 90 min. A pharmacokinetic analysis was performed using the NONMEM statistical programme. The use of epinephrine in the solution was included in the analysis of covariates. The associated risk of LAST symptoms associated with different levobupivacaine dose schemes with and without epinephrine was estimated in 1000 simulated subjects.

RESULTS

A one-compartment first-order input and elimination model adequately fit the levobupivacaine data. Epinephrine prolonged the levobupivacaine absorption half-life {4.22 [95 % confidence interval (CI) 2.53-6.50] vs. 7.02 [95 % CI 3.74-14.1]; p < 0.05} and reduced its relative bioavailability (0.84; 95 % CI 0.72-0.97; p < 0.05) The derived model predicts that levobupivacaine dose schemes should be halved from 3 mg kg(-1) body weight with epinephrine to 1.5 mg kg(-1) without epinephrine to obtain a comparable risk of anaesthetic toxicity symptoms of approximately 0.1 %.

CONCLUSIONS

Our results strongly support the addition of epinephrine to the local anaesthetic solution, especially when doses of levobupivacaine of >1.5 mg kg(-1) are required. Recommendations regarding the maximum allowable doses of local anaesthetics should consider population analysis to determine safer dosage ranges.

Unilateral Ultrasound-Guided Transversus Abdominis Plane Block After Nephrectomy; Postoperative Pain and Use of Opioids

Background

Pain has a wide spectrum of effects on the body and inadequately controlled postoperative pain may have harmful physiologic and psychological consequences and increase morbidity. In addition, opioid anesthetic agents in high doses can blunt endocrine and metabolic responses following surgery and are associated with side effects including dizziness, nausea, vomiting, constipation, and respiratory depression.

Objectives

The current study aimed to investigate if unilateral ultrasound-guided transverse abdominal plane block (TAP-block) could reduce pain and postoperative use of patient requested analgesics following nephrectomy compared to local injection of the same ropivacaine dose in the surgical wound.

Patients and Methods

Retrospective chart reviews were performed in 42 consecutive patients who received TAP-block in conjunction with nephrectomy from November 2013 to August 2014 (group A). For comparison, data were used from 40 other nephrectomy patients registered as part of a previous study (group B). In this group the patients had received local ropivacaine injection in the surgical wound. On univariate analyses, the groups were compared by t-test and the Fisher exact test. Multivariate analyses were conducted by multiple linear regression.

Results

Mean surgical time was 162 minutes in group A and 92 minutes in group B (P < 0.0001). The means of visual analogue scale (VAS) were 3.05 and 1.55 in A and B groups, respectively (P = 0.001). The means of morphine consumption were 5.2 mg and 5.9 mg in groups A and B, respectively (P = 0.58); while the means of sufentanil use were 9.8 μg and 6.0 μg in groups A and B, respectively (P = 0.06). When controlling for age, tumor size and American society of anesthesiologists classification (ASA) score on multivariate analysis, TAP-block was associated with a significant increase in VAS (+1.4 [95% CI, 0.6 - 2.3], P = 0.001) and sufentanil use (+6.2 μg [95% CI, 2.3 - 10.2], P = 0.003). There was no difference in morphine use on multivariate analysis (P = 0.99).

Conclusions

TAP-block in conjunction with laparoscopic nephrectomy did not reduce pain or opioid consumption. On the contrary, it seemed to prolong surgical time.

The Analgesic Efficacy of Ultrasound-Guided Transversus Abdominis Plane Block in Adult Patients: A Meta-Analysis

BACKGROUND

Previous meta-analyses of the transversus abdominis plane (TAP) block have examined a maximum of 12 articles, including fewer than 650 participants, and have not examined the effect of ultrasound-guided techniques specifically. Recently, many trials that use ultrasound approaches to TAP block have been published, which report conflicting analgesic results. This meta-analysis aims to evaluate the analgesic efficacy of ultrasound-guided TAP blocks exclusively for all types of abdominal surgeries in adult patients.

METHODS

This meta-analysis was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement guidelines. The primary outcome was cumulative IV morphine consumption at 6 hours postoperatively, analyzed according to the type of surgery, the type of surgical anesthesia, the timing of injection, the block approach adopted, and the presence of postoperative multimodal analgesia. Secondary outcomes included IV morphine consumption at 24 hours postoperatively; pain scores at rest and on movement at 6 and 24 hours postoperatively; and postoperative nausea and vomiting, pruritus, and rates of complications.

RESULTS

Thirty-one controlled trials including 1611 adult participants were identified. Independent of the type of surgery (abdominal laparotomy, abdominal laparoscopy, and cesarean delivery) but not independent of the type of surgical anesthesia (general anesthesia, spinal anesthesia with or without intrathecal long-acting opioid), ultrasound-guided TAP block reduced IV morphine consumption at 6 hours postoperatively by a mean difference of 6 mg (95% confidence interval [CI], -7 to -4 mg; I2 = 94%; P < 0.00001). The magnitude of the reduction in morphine consumption at 6 hours postoperatively was not influenced by the timing of injection (I2 = 0%; P = 0.72), the block approach adopted (I2 = 0%; P = 0.72), or the presence of postoperative multimodal analgesia (I2 = 73%; P = 0.05). This difference persisted at 24 hours postoperatively (mean difference, -11 mg; 95% CI, -14 to -8 mg; I2 = 99%; P < 0.00001). Pain scores at rest and on movement were reduced at 6 hours postoperatively (mean difference at rest, -10; 95% CI, -15 to -5; I2 = 92%; P = 0.0002; mean difference on movement, -9; 95% CI, -14 to -5; I2 = 58%; P < 0.00001). There were neither differences in the incidence of postoperative nausea and vomiting (I2 = 1%; P = 0.59) nor in the pruritus (I2 = 12%; P = 0.58) Two minor complications (1 bruise and 1 anaphylactoid reaction) were reported in 1028 patients.

CONCLUSIONS

Ultrasound-guided TAP block provides marginal postoperative analgesic efficacy after abdominal laparotomy or laparoscopy and cesarean delivery. However, it does not provide additional analgesic effect in patients who also received spinal anesthesia containing a long-acting opioid. The minimal analgesic efficacy is independent of the timing of injection, the approach adopted, or the presence of postoperative multimodal analgesia. Because of heterogeneity of the results, these findings should be interpreted with caution.

Regional anaesthesia in neonates, infants and children: an educational review

Prophylactic analgesia with local anaesthesia is widely used in children and has a good safety record. Performing regional blocks in anaesthetised children is a safe and generally accepted practice. When compared with adults, lower concentrations of local anaesthetics are sufficient in children; the onset of a block occurs more rapidly but the duration is usually shorter. Local anaesthetics have a greater volume of distribution, a lower clearance and a higher free (non-protein-bound) fraction. The recommended maximum dose has to be calculated for every individual. Peripheral blocks provide analgesia restricted to the site of surgery, and some of them have a very long duration of action. Abdominal wall blocks, such as transverse abdominis plane or ilio-inguinal nerve block, should be performed with the aid of ultrasound. Caudal anaesthesia is the single most important technique. Ropivacaine 0.2% or levobupivacaine 0.125 to 0.175% at roughly 1 ml  kg⁻¹ is adequate for most indications. Clonidine and morphine can be used to prolong the duration of analgesia. Ultrasound is not essential for performing caudal blocks, but it may be helpful in case of anomalies suspected at palpation and for teaching purposes. The use of paediatric epidural catheters will probably decline in the future because of the potential complications.

Transversus abdominis plane (TAP) block after robot-assisted laparoscopic hysterectomy: a randomised clinical trial

BACKGROUND

Transversus abdominis plane (TAP) block is widely used as a part of pain management after various abdominal surgeries. We evaluated the effect of TAP block as an add-on to the routine analgesic regimen in patients undergoing robot-assisted laparoscopic hysterectomy.

METHODS

In a prospective blinded study, 70 patients scheduled for elective robot-assisted laparoscopic hysterectomy were randomised to receive either TAP block (ropivacaine 0.5%, 20 ml on each side) or sham block (isotonic saline 0.9%, 20 ml on each side). All patients had patient-controlled analgesia (PCA) with morphine on top of paracetamol and ibuprofen or diclofenac. For the first 24 post-operative hours, we monitored PCA morphine consumption and pain scores with visual analogue scale (VAS) at rest and while coughing. Post-operative nausea and number of vomits (PONV) were recorded.

RESULTS

Sixty-five patients completed the study, 34 receiving TAP block with ropivacaine and 31 receiving sham block with isotonic saline. We found no differences in median (interquartile range) morphine consumption the first 24 h between the TAP block group [17.5 mg (6.9-36.0 mg)] and the placebo group [17.5 mg (2.9-38.0 mg)] (95% confidence interval 10.0-22.6 mg, P = 0.648). No differences were found for VAS scores between the two groups, calculated as area under the curve/1-24 h, neither at rest (P = 0.112) nor while coughing (P = 0.345), or for PONV between groups.

CONCLUSIONS

In our study, the TAP block combined with paracetamol and Nonsteroidal anti-inflammatory drugs (NSAID) treatment, had no effect on morphine consumption, VAS pain scores, or frequency of nausea and vomiting after robot-assisted laparoscopic hysterectomy compared with paracetamol and NSAID alone.

Ropivacaine (total and unbound) and AGP concentrations after transversus abdominis plane block for analgesia after abdominal surgery

BACKGROUND

The goal of this study was to assess the safety of single bolus dose of ropivacaine (ROP) followed by continuous infusion through transversus abdominis plane block catheter. The aim was to determine ROP absorbed from the infusion site, changes in protein binding after surgery, and clinical determinants of adverse effects.

METHODS

Twelve patients undergoing laparotomy, received bilateral transversus abdominis plane block under ultrasound guidance using a 20-mL bolus of 0.5% ROP followed by 10 mL/h of 0.2% ROP infusion for 48 hours. Serial blood samples were drawn presurgery and to 48 hours postbolus. Plasma concentrations of total and unbound ROP were measured by high performance liquid chromatography with ultraviolet detection. Alpha-1 acid glycoprotein concentrations were measured by enzyme-linked immunosorbent assay. Patients were monitored for any signs or symptoms of central nervous system and chorionic villus sampling toxicity.

RESULTS

After the bolus dose, the mean (±SD) peak plasma total (bound plus unbound) ROP concentration (Cmax) was 2.1 (±0.8) mg/L and unbound ROP concentration was 0.04 (±0.02) mg/L. During the infusion phase, total ROP concentration continued to rise to a mean (±) Cmax of 3.3 (±1.6) mg/L, and the peak unbound concentration was 0.06 (±0.0) mg/L. No patients showed symptoms of ROP toxicity or unacceptable QTc intervals.

CONCLUSIONS

Although the total ROP concentrations approached or exceeded reported neurotoxicity thresholds, no patients had unbound ROP concentrations approaching the unbound toxicity threshold, nor showed any signs or symptoms of toxicity. This result was consistent with changes in protein binding to alpha-1 acid glycoprotein after surgery.

Ultrasound-guided tranversus abdominis plane block for herniorrhaphy in children: what is the optimal dose of levobupivacaine?

BACKGROUND

Regional anaesthesic techniques are commonly used for the management of pain following lower abdominal surgery in children. The transversus abdominis plane (TAP) block has shown promise for perioperative analgesia, but data on the optimal dose regimen are limited.

OBJECTIVE

To evaluate the optimal dose of levobupivacaine for successful ultrasound-guided TAP block in children.

DESIGN

A dose finding prospective study using Dixon's up-and-down sequential method.

SETTING

University Hospital Paediatric Anaesthesia Unit.

PATIENTS

Twenty-seven consecutive children aged 1 to 5 years scheduled for day-case elective herniorrhaphy.

INTERVENTION

After standardised induction of general anaesthesia, ultrasound-guided TAP block was performed with a fixed volume of 0.2  ml  kg(-1) of levobupivacaine solution. The dose of levobupivacaine was determined by Dixon's up-and-down method starting from 0.5  mg  kg(-1)with an interval of 0.1 mg   kg(-1). Block failure was defined as a 20% increase in heart rate or mean arterial pressure from baseline. Rescue analgesia consisted of intravenous remifentanil infusion during surgery and intravenous nalbuphine in the postanaesthetic care unit (PACU). Patients were assessed using the FLACC (face, legs, activity, cry and consolability) pain scale, the rescue analgesic consumption in the PACU and day-case unit and the postoperative pain measure for parents score at home.

MAIN OUTCOME MEASURES

The mean effective dose of levobupivacaine resulting in an effective TAP block in 50% of cases (ED50) obtained by using Dixon's up-and-down sequential method. The ED50 and ED95 were further estimated by bootstrapping.

RESULTS

The ED50 according to the up-and-down staircase method was 0.22  mg   kg(-1) [95% confidence interval (CI) 0.19 to 0.25]. Bootstrap replicates of the original dataset resulted in ED50 and ED95 estimates of 0.16  mg    kg(-1) (95% CI 0.11 to 0.24) and 0.43 mg  kg(-1)(95% CI 0.30 to 0.57), respectively.

CONCLUSION

As part of a multimodal analgesia strategy, ultrasound-guided TAP block with 0.2  ml  kg(-1)of 0.2% levobupivacaine provides successful peroperative analgesia in 95% of children who underwent herniorrhaphy.

Ultrasound-guided rectus sheath block or wound infiltration in children: a randomized blinded study of analgesia and bupivacaine absorption

BACKGROUND

Rectus sheath block can provide analgesia following umbilical hernia repair. However, conflicting reports on its analgesic effectiveness exist. No study has investigated plasma local anesthetic concentration following ultrasound-guided rectus sheath block (USGRSB) in children.

OBJECTIVES

Compare the effectiveness and bupivacaine absorption following USGRSB or wound infiltration (WI) for umbilical hernia repair in children.

METHODS

A randomized blinded study comparing WI with USGRSB in 40 children undergoing umbilical hernia repair was performed. Group WI (n = 20) received wound infiltration 1 mg·kg(-1) 0.25% bupivacaine. Group RS (n = 20) received USGRSB 0.5 mg·kg(-1) 0.25% bupivacaine per side in the posterior rectus sheath compartment. Pain scores and rescue analgesia were recorded. Blood samples were drawn at 0, 10, 20, 30, 45, and 60 min.

RESULTS

Patients in the WI group had a twofold increased risk of requiring morphine (hazard ratio 2.06, 95% CI 1.01, 4.20, P = 0.05). When required, median time to first morphine dose was longer in the USGRSB group (65.5 min vs. 47.5 min, P = 0.049). Peak plasma bupivacaine concentration was higher following USGRSB than WI (median: 631.9 ng·ml(-1) IQR: 553.9-784.1 vs. 389.7 ng·ml(-1) IQR: 250.5-502.7, P = 0.002). Tmax was longer in the USGRSB group (median 45 min IQR: 30-60 vs. 20 min IQR: 20-45, P = 0.006).

CONCLUSIONS

USGRSB provides more effective analgesia than WI for umbilical hernia repair. USGRSB with 1 mg·kg(-1) 0.25% bupivacaine is associated with safe plasma bupivacaine concentration that peaks higher and later than WI. Caution against using larger volumes of higher concentration local anesthetic for USGRSB is advised.

Ultrasound-guided transversus abdominis plane (TAP) block for laparoscopic gastric-bypass surgery: a prospective randomized controlled double-blinded trial

BACKGROUND

Despite the laparoscopic approach, patients can suffer moderate to severe pain following bariatric surgery. This randomized controlled double-blinded trial investigated the analgesic efficacy of ultrasound-guided transversus abdominis plane (TAP) blocks for laparoscopic gastric-bypass surgery.

METHODS

Seventy patients undergoing laparoscopic gastric-bypass surgery were randomized to receive either bilateral ultrasound-guided subcostal TAP block injections after induction of general anesthesia or none. All patients received trocar insertion site local anesthetic infiltration and systemic analgesia. The primary outcome was cumulative opioid consumption (IV morphine equivalent) during the first 24 h postoperatively. Interval opioid consumption, pain severity scores, rates of nausea or vomiting, and rates of pruritus were measured during phase I recovery, and at 24 and 48 h postoperatively.

RESULTS

There was no difference in cumulative opioid consumption during the first 24 h postoperatively between the TAP (32.2 mg [95% CI, 27.6-36.7]) and control (35.6 mg [95% CI, 28.6-42.5]; P = 0.41) groups. Postoperative opioid consumptions during phase I recovery and the 24-48-h interval were similar between groups, as were pain scores at rest and with movement during all measured intervals. The rates of nausea or vomiting and pruritus were equivalent.

CONCLUSIONS

Bilateral TAP blocks do not provide additional analgesic benefit when added to trocar insertion site local anesthetic infiltration and systemic analgesia for laparoscopic gastric-bypass surgery.

Bilateral transversus abdominis plane (TAP) block with 24 hours ropivacaine infusion via TAP catheters: A randomized trial in healthy volunteers

Background

The analgesic effect of a TAP block has been investigated in various surgical settings. There are however limited information about block level and block duration. Furthermore, there is a lack of information about continuous TAP block after ultrasound-guided posterior TAP blocks.

The aim of this double-blind randomized study was therefore to investigate the effect of an ultrasound-guided posterior TAP block with 24 hours local anesthetic infusion via a TAP catheter.

Methods

In this randomized study 8 male volunteers received a bilateral TAP block (20 mLs 0.5% ropivacaine) and were allocated to receive active infusion (ropivacaine 0.2% 5 mL/hr) via a TAP catheter on one side and placebo infusion on the other side. Primary outcome: Dermatomal sensory block involvement after 24 hours evaluated with pinprick. Secondary outcomes: Sensory block involvement evaluated with cold test and heat-pain detection thresholds (HPDT) on the abdominal wall. Assessment points: 15 min before block performance and 1, 4, 8, 12 and 24 hours after block performance.

Results

The TAP block primarily involved sensory changes in the Th10 to Th12 dermatomes. On the placebo side there was a decrease in extension beginning at 4–8 hours after block performance and with no detectable effect beyond 12 hours. Median number of dermatomes anesthetized (pinprick) at 24 hours after block performance was 1.5 (0–3) on the active side compared with 0 (0–0) on the placebo side (P = 0.039).

There were no statistical significant between-side differences in HPDT measurements at 24 hours after block performance.

Conclusions

The spread of sensory block following ultrasound-guided posterior TAP block is partly maintained by a continuous 24 hour ropivacaine infusion through a TAP catheter.

Trial registration

The study was registered at NCT01577940

Comparison of plasma concentrations of levobupivacaine with and without epinephrine for transversus abdominis plane block

BACKGROUND AND OBJECTIVES

The pharmacokinetics for levobupivacaine in transversus abdominis plane (TAP) blocks has not been previously reported. We aimed to determine the extent of the block and the effect on plasma concentrations of levobupivacaine with the addition of epinephrine.

METHODS

We enrolled 11 healthy volunteers in this double-blind, 2-intervention, 2-period crossover study. The intervention periods were defined as a unilateral left TAP block with 20 mL of 0.25% levobupivacaine with (E) or without (no E) 5 μg/mL epinephrine. Subjects were randomized to E, followed by no E or no E followed by E, with 2-week washout period. Sensory dermatomal anesthesia was recorded. Blood samples were obtained for the measurement of plasma levobupivacaine levels.

RESULTS

The median cranial-to-caudal spread of sensory blockade for sharp touch was T9 (interquartile range [IQR], T7-T10) to L1 (IQR, T12-L1) with epinephrine and T9 (IQR, T8-T10) to T12 (IQR, T11-L1) without epinephrine (P > 0.05). The mean maximum arterial levobupivacaine concentrations with epinephrine were 0.36 (95% bootstrap confidence interval [95% CI], 0.30-0.42) μg/mL and 0.63 (95% CI, 0.49-0.85) μg/mL without epinephrine (P = 0.014, difference in means of 0.27 [95% CI, 0.12-0.46]). The mean maximal venous levobupivacaine concentration was 0.32 (95% CI, 0.28-0.39) μg/mL and 0.49 (95% CI, 0.37-0.68) μg/mL, with and without epinephrine, respectively (P = 0.006, difference in means of 0.17 [95% CI, 0.08-0.33]). The mean duration of the blockade was 10.2 hours (95% CI, 8.5-12.5 hours) with epinephrine and 10.3 hours (95% CI, 8.7-12.4 hours) without epinephrine (P = 1.000).

CONCLUSIONS

Adding epinephrine to levobupivacaine reduces its peak plasma concentration after unilateral TAP blocks, with no remarkable effects on block characteristics or duration.

Transversus abdominis plane block

PURPOSE OF REVIEW

Since the publication of original work on the transversus abdominis plane (TAP) block, the translation of the research into clinical practice has resulted in some 146 articles being published in peer-reviewed journals. However, there continues to be controversies over the best approach to be used. The introduction of ultrasound should have aided the development of this block, but in fact it has caused more questions to be asked. There are a number of reviews of the block already published, but were they published too early and what is our current understanding of the TAP block and its mechanisms of action?

RECENT FINDINGS

The TAP block continues to develop. We now understand that the TAP block is a multifaceted block, working with both localized field effects as well as distal effects due to a distant spread of local anesthetic. Recent research would suggest that the location of needle tip placement causes variation in the block characteristics obtained. The more anterior approaches adopted for use since the introduction of ultrasound might be better described as RAFI (regional abdominal field infiltration) blocks.

SUMMARY

The TAP block, in all its guises, is an effective analgesic tool, but what is the best approach? Randomized controlled trials comparing the TAP/RAFI blocks to epidural based analgesia are required.

Autologous blood transfusion after local infiltration analgesia with ropivacaine in total knee and hip arthroplasty

Aims. To study the safety of autotransfusion following local infiltration analgesia (LIA) with ropivacaine. Background. Knowledge of blood concentrations of ropivacaine after LIA and autotransfusion is crucial. However, very limited data are available for toxicological risk assessment. Methods. Autotransfusion was studied in patients after total knee arthroplasty (TKA: n = 25) and total hip arthroplasty (THA: n = 27) with LIA using 200 mg ropivacaine, supplemented with two postoperative bolus injections (150 mg ropivacaine). Drainage blood was reinfused within 6 h postoperatively. Results. Reinfusion caused a significant increase in the serum concentration of total ropivacaine for TKA from 0.54 ± 0.17 (mean ± SD) to 0.79 ± 0.20 μg/mL (P < 0.001) and a nonsignificant increase for THA from 0.62 ± 0.17 to 0.63 ± 0.18 μg/mL. The maximum free (unbound) concentration after reinfusion was 0.038 μg/mL. Peak total and free venous ropivacaine concentrations after 8 h and 16 h postoperative bolus injections were 2.6 μg/mL and 0.11 μg/mL, respectively. All concentrations observed were below the threshold for toxicity and no side effects were observed. Conclusion. Autotransfusion of patients undergoing knee or hip arthroplasty after local infiltration analgesia with 200 mg ropivacaine can be performed safely, even supplemented with 8 h and 16 h postoperative bolus injections.