Ropivacaine Undergoes Slower Systemic Absorption from the Caudal Epidural Space in Children than Bupivacaine

Ultrasound-guided epidural anesthesia and sedation for open transvesical Cohen ureteric reimplantation surgery in 20 consecutive children: a prospective case series and proof-of-concept study

BACKGROUND

Epidural anesthesia is usually combined with general anesthesia (GA) for children undergoing sub-umbilical surgery and GA in children is associated with a potential for respiratory events. Aiming to reduce airway manipulation and the use of GA drugs, we designed a study of transvesical Cohen ureteteric reimplantion under epidural anesthesia in sedated, spontaneously breathing children.

METHODS

We enrolled 20 children (3-83 months, 6.3-25.0 kg) scheduled for open transvesical abdominal surgery with Pfannenstiel incision. Sedation was followed by ultrasound-guided epidural anesthesia. Increases in heart rate by > 15% and or patient movements upon skin incision were rated as block deficiencies. Intubation equipment for advanced airway management was kept on standby. The primary study endpoint was successful blockade, meaning that no sequential airway management was required for the spontaneous breathing patients during surgery. Secondary endpoints included any use of fentanyl/propofol intraoperatively and of postoperative analgesics in the recovery room.

RESULTS

All 20 blocks were successful, with no block deficiencies upon skin incision, no need for sequential airway management, and stable SpO2 levels (97-100%). Surgery took a median of 120.5 minutes (IQR: 89.3-136.5) and included one bolus of fentanyl in one patient 120 minutes into a protracted operation. No more systemic analgesia had to be provided in the recovery room.

CONCLUSIONS

Sedation and epidural anesthesia emerged as a useful alternative to GA from our consecutive case series.

Pharmacokinetics of sufentanil administered with 0.2% ropivacaine as a continuous epidural infusion for postoperative pain relief in infants

BACKGROUND AND OBJECTIVES

Our objective was to assess plasma sufentanil concentrations and postinfusion pharmacokinetics in infants receiving 0.2% ropivacaine with sufentanil as a continuous epidural infusion for postoperative pain relief.

METHODS

With consent of local ethics committee and informed parental consent, 20 infants 3-36 months old (m.o.) (median 9.3 m.o., 9.0 [3.5-15] kg, ASA PS I/II) were enrolled. Epidural catheter was placed under general anesthesia in L3-L4, L4-L5, or L2-L3 interspace and threaded not farther than 4 cm into epidural space. After initial bolus of 0.2% ropivacaine, 0.5 ml·kg(-1) and sufentanil 200 ng·kg(-1) , continuous infusion of 0.2% ropivacaine, 0.3 mg·kg(-1) ·h(-1) with sufentanil 112 ng·kg(-1) ·h(-1) was started. For the postoperative period, sufentanil dose was reduced to 37 ng·kg(-1) ·h(-1) . Blood samples were drawn at the end of surgery, 24 h later, by the end of 2nd day of infusion and after 3, 6, and 18 h from the end of infusion. Sufentanil was measured using liquid-liquid extraction (LLE) procedure and HPLC-MS/MS method with LOQ = 5 pg·ml(-1) .

RESULTS AND CONCLUSIONS

Elimination of sufentanil following epidural administration was very slow, with MRT = 28.25 [18.36-44.75] h and t1/2 MRT  = 19.57 [12.72-31.01] h. In infants, during a long-term infusion of sufentanil with ropivacaine, the opioid concentration in plasma increases during the postoperative infusion itself, then increases even further after discontinuation of the infusion, in some cases reaching the values consistent with a potential risk of respiratory depression. Meticulous monitoring of the infants' vital signs is therefore mandatory not only during the infusion, but also for several hours after its discontinuation.

Peripheral catheter techniques

With ultrasound, continuous peripheral nerve blocks (CPNBs) are one of the most recent developments in regional anesthesia in children. CPNBs are now used more widely in children because more suitable materials have been marketed, allowing complete, and prolonged postoperative pain control. Their use after orthopedic procedures in children and treatment for complex regional pain syndrome in adolescents has demonstrated the benefits. Perineural catheters have also shown their superiority over other techniques of continuous regional anesthesia in terms of side effects. The efficiency and the safety of these techniques may facilitate early ambulation with improved pain management, treatment at home with disposable pumps, and improved rehabilitation of children. Studies on large cohorts of patients published to date have failed to highlight any severe complications in their use compared with other adult studies. Accidents owing to systemic toxicity are very unlikely if the recommended maximum dose is not exceeded. The safety of continuous regional anesthesia techniques in children relies on the use of low-concentration l-enantiomer solutions (ropivacaine or levobupivacaine) accompanied by low plasma concentrations of local anesthetics, limiting the risk of systemic toxicity of these molecules. CPNB can ensure strong and lasting analgesia in hospital or at home.

Minimum local analgesic concentration of ropivacaine for intra-operative caudal analgesia in pre-school and school age children

We compared the minimum local analgesia concentration of ropivacaine for intra-operative caudal analgesia in pre-school and school age children. Fifty-one boys, undergoing hypospadius repair surgery, were stratified into pre-school or school age groups. After induction of anaesthesia, caudal block was performed with ropivacaine 1 ml.kg⁻¹ of the desired concentration. The first child in each group received ropivacaine 0.125%, and subsequent concentrations were determined by the analgesic response of the previous patient using Dixon's up-and-down method. Under general anaesthesia with 0.7 minimum alveolar concentration of sevoflurane, the minimum local analgesia concentration of ropivacaine for intra-operative caudal block was 34% greater in school age than in pre-school age boys (0.143% (95% CI 0.132-0.157%) vs 0.107% (95% CI 0.089-0.122%), respectively; p < 0.001). This study indicates that a higher concentration of ropivacaine is needed for school age than pre-school age children to provide intra-operative caudal analgesia when combined with general anaesthesia.

The analgesic efficacy of continuous wound instillation with ropivacaine after open hepatic surgery

The analgesic efficacy of continuous local anaesthetic wound instillation after open hepatic surgery was evaluated. Forty-eight patients scheduled for elective liver surgery were assigned to receive either ropivacaine 0.25% or saline infusion at 4 ml.h(-1) for 68 h via two multi-orifice indwelling catheters placed within the musculo-fascial layer before skin closure; plasma ropivacaine concentrations were measured during the infusion. Supplemental analgesia was provided by intravenous patient-controlled analgesia morphine. Patients in the ropivacaine group had decreased mean (SD) total morphine consumption (58 (30) mg vs 86 (44) mg, p = 0.01) and less pain at rest as well as after spirometry at 4, 12, 24, 48 and 72 h postoperatively (p < 0.01). Forced vital capacity was reduced postoperatively in both groups, but the reduction was greater in the saline group at 12 and 24 h (p = 0.03). The mean plasma concentration of ropivacaine increased to 2.05 (0.78) μg.ml(-1) at the point when the infusion was terminated.

Plasma ropivacaine concentrations after ultrasound-guided transversus abdominis plane block

BACKGROUND

The transversus abdominis plane block is a novel technique involving injection of local anaesthetic between the internal oblique and the transversus abdominis muscles of the abdominal wall. It is possible that injection of a large dose of local anaesthetic into a relatively vascular plane may result in toxic concentrations. One previously published study examined plasma lidocaine concentrations after transversus abdominus plane block and showed potentially toxic plasma concentrations. Although ropivacaine is most commonly used for this technique, plasma concentrations of ropivacaine after this block have not been reported previously.

METHODS

Adult female patients undergoing elective open gynaecological surgery received bilateral ultrasound-guided transverse abdominal plane blocks before surgical incision (3 mg kg(-1) of ropivacaine diluted to 40 ml). Venous blood was collected each 15 min for the first hour, each 30 min for the second hour, and then at 3, 4, 12, and 24 h post-block.

RESULTS

Twenty-eight patients were recruited. The mean (sd) peak total ropivacaine concentration occurred 30 min post-injection and was 2.54 (sd 0.75) µg ml(-1). The highest measured concentration was 4.00 µg ml(-1), also 30 min post-injection. Mean total concentrations remained above 2.20 µg ml(-1) for up to 90 min post-injection. The mean unbound peak venous concentration was 0.14 (0.05) µg ml(-1), and the peak was 0.25 µg ml(-1).

CONCLUSIONS

Transversus abdominus plane block using 3 mg kg(-1) of ropivacaine produces venous plasma concentrations that are potentially neurotoxic, although broadly consistent with plasma levels found after injection at other comparable sites.

Effects of preoperative local ropivacaine infiltration on postoperative pain scores in infants and small children undergoing elective cleft palate repair

Previous data have shown that preoperative analgesia may reduce postoperative analgesic demands. The aim of the current study was to determine if preincisional ropivacaine infiltration may reduce postoperative oral pain in infants and small children undergoing elective cleft palate patients.Twenty nonsyndromic cleft palate patients were randomly divided into 2 groups. Injection with ropivacaine hydrochloride, at dose of 0.2 mg/kg, was performed by submucous infiltration of the proposed incisional site groups of patients. In control group, no medication was given before cleft palate repair under general anesthesia. Postoperative pain scores were measured according to Children and Infants Postoperative Pain Scale. Heart rate recordings and noninvasive blood pressure measurements were also done in all the patients.Measurements of Children and Infants Postoperative Pain Scale scores at all the observational postoperative periods showed significantly favorable values in ropivacaine group than in control group (P < 0.05). Six patients in the control group required rescue analgesia, whereas 2 patients required analgesic therapy in the treatment group.Preemptive analgesia using ropivacaine may enhance early postoperative comfort by reducing early postoperative pain in primary cleft repair.

Ropivacaine may have advantages compared to bupivacaine in porcine endotoxemic shock

Patients that undergo major abdominal surgery often receive epidural postoperative analgesia. Septic complications are frequently seen in this cohort. In a porcine model of endotoxemic shock, resembling human gram-negative septic shock, we evaluated the effects of two widely used local anaesthetics, bupivacaine and ropivacaine given intravenously. In the endotoxin-ropivacaine group mixed venous saturation and platelet count were higher as compared to endotoxemic controls. Mean arterial blood pressure and platelet count were higher in ropivacaine-endotoxin pigs than in bupivacaine-endotoxin ones. Bupivacaine augmented endotoxin-mediated decrease in left ventricular stroke work index. Ropivacaine displays pathophysiological advantages compared to bupivacaine in septic shock, which may be explained by improved tissue perfusion by ropivacaine.

In children, the addition of epinephrine modifies the pharmacokinetics of ropivacaine injected caudally

PURPOSE

To describe the modification of the ropivacaine (R) pharmacokinetics produced by the addition of epinephrine (E).

METHODS

After Institutional Review Board approval, 18 ASA I boys received a caudal block (1 mL x kg(-1)) with either plain 0.2% R (Group E-) or with 0.2% R containing E (5 microg x mL(-1); Group E+). Venous blood samples were taken at zero, 15, 30, 60, 90, 120, 180, 240, 420, 720, 1440 min after caudal injection. Total R concentration in plasma was determined by high pressure liquid chromatography. Maximal concentration (C(max)) and time to peak concentration (T(max)) were obtained from the data, terminal half-life (T(1/2z)), clearance (Cl) and volume of distribution (Vd) were estimated by a non-compartmental approach. Subsequently, in order to determine the absorption rate (Ka) and to reduce to number of blood samples, 25 other children, receiving plain R and another group of 25 receiving the E solution were studied using a population approach (NONMEM). A one compartment model with first order absorption was used. The effect of weight, age and E on Cl, Vd and Ka was estimated.

RESULTS

C(max) was significantly lower in Group E+ (0.93 mg x L(-1) +/- 0.29 vs 0.61 mg x L(-1) +/- 0.28, P = 0.05) and T(max) occurred later (124 min +/- 53 vs 47 min +/- 16, P = 0.003). Weight was a significant covariate for Cl and Vd while E significantly slowed R Ka [Group I Ka 0.025 min(-1) [coefficient of variation (CV) 21%] vs 0.078 min(-1) (CV 25%) in Group II].

CONCLUSION

The addition of E significantly modifies the pharmacokinetics of R injected caudally.