Pharmacokinetics of bupivacaine following intraoperative intercostal nerve block in neonates and in infants aged less than 6 months

Continuous epidural chloroprocaine after abdominal surgery is associated with lower postoperative opioid exposure in NICU infants

BACKGROUND

Epidural anesthesia in infants undergoing open abdominal surgery has the potential to reduce opioid consumption, lower pain scores, and expedite tracheal extubation. We evaluated associations between use of continuous epidural chloroprocaine and improved intra- and post-operative outcomes.

METHODS

This matched retrospective cohort study first identified 24 patients who between April 2018 through December 2019 were treated with a caudal catheter and epidural chloroprocaine infusion for a laparotomy at postnatal age of 6 months or less. A matched comparator group of 24 patients was derived based on age and type of surgery. Exclusion criteria were the presence of a preoperative opioid infusion, comorbidities that would preclude appropriate pain assessment, or a recent surgical procedure. Primary outcomes included opioid consumption and pain scores; we secondarily analyzed intraoperative anesthetic requirements, other systemic analgesic use, vital signs, tracheal extubation time, and procedural times.

RESULTS

Treatment with epidural anesthesia was associated with lower 5-day total postoperative opioid consumption (3.2 mg/kg vs. 19.7 mg/kg in the respective epidural vs. systemic groups, p = 0.001) and time to tracheal extubation (1.3 days vs. 3.2 days, p = 0.005). Any statistically significant differences in pain scores were not clinically meaningful. There were no differences in mean arterial pressure or intraoperative inhaled anesthetic doses.

CONCLUSION

Continuous infusion of epidural chloroprocaine in infants following open abdominal surgery may limit exposure to systemic opioid medications while providing adequate postoperative analgesia and shortening time to tracheal extubation.

Regional anesthesia in neonates and infants outside the immediate perioperative period: A systematic review of studies with efficacy and safety considerations

This review examines the quality and quantity of literature regarding methods that measure efficacy in the context of reported safety of regional anesthesia techniques in preterm and term infants <1 year of age. Because the role of anesthesiologists continues to expand outside the operating room, we focused on all relevant settings with assessments that extend beyond 24 hours from the intraoperative period. All study designs were included from a search of MEDLINE, EMBASE, CINAHL, Scopus, and Cochrane databases from 1946 to the end of 2019. A total of 31 studies were included (n = 1038 participants), consisting of five randomized controlled trials and 26 observational studies. Twenty-three studies examined neuraxial procedures, seven studies examined peripheral procedures, and one study examined both. Efficacy measures included pain assessment tools, analgesic use, and factors pertaining to the recovery of patients. Safety was assessed in multiple systems (neurological, cardiovascular, respiratory, pathological) and with vital signs and/or measures of systemic toxicity. Evidence in this review establishes that neuraxial and peripheral anesthesia treatments may be applied to neonates and infants with a high degree of safety. However, large gaps in the consistency of methods used to assess pain in these studies underline the need for rigorous prospective efficacy studies of these techniques in this population. This systematic review was registered on PROSPERO (CRD42018114466).

Exploring the transversus abdominis plane block in cesarean sections and the subsequent toxicity risk to neonates via breast milk

The transversus abdominis plane (TAP) block with its wide application has shown to be an analgesic effective for use in abdominal surgeries, including for cesarean section. However, the bupivacaine delivered in the TAP block comes with the risk of toxicity, both central nerve system (CNS) and cardiovascular system, and has been shown in some instances to reach maximum serum concentrations in excess of the 2 μg/mL associated with the lower end of CNS toxicity. There is a specific concern with cesarean section TAP blocks of the anesthetic passage to the neonate via maternal breast milk and whether this poses a toxicity risk. Bupivacaine has been shown to pass into maternal milk at concentrations 0.34 times the maternal serum concentration. Preliminary statistical analyses suggest that the bupivacaine delivered in breast milk is not in concentrations high enough to cause neonatal toxicity, but further studies would be useful in identifying what the toxicity risk is, if any, to the neonates' breastfeeding after the delivery and TAP block.

Neonatal pain management

The past 2-3 decades have seen dramatic changes in the approach to pain management in the neonate. These practices started with refuting previously held misconceptions regarding nociception in preterm infants. Although neonates were initially thought to have limited response to painful stimuli, it was demonstrated that the developmental immaturity of the central nervous system makes the neonate more likely to feel pain. It was further demonstrated that untreated pain can have long-lasting physiologic and neurodevelopmental consequences. These concerns have resulted in a significant emphasis on improving and optimizing the techniques of analgesia for neonates and infants. The following article will review techniques for pain assessment, prevention, and treatment in this population with a specific focus on acute pain related to medical and surgical conditions.

Combined use of neuraxial and general anesthesia during major abdominal procedures in neonates and infants

With the advent of ultrasound and improvements in equipment, the applications of regional anesthesia in the pediatric population have continued to expand. Although frequently used for postoperative analgesia or as a means of avoiding general anesthesia in patients with comorbid conditions, the adjunctive use of regional anesthesia during general anesthesia may effectively decrease the intraoperative requirements for intravenous and volatile agents, thereby providing a more rapid awakening and earlier tracheal extubation. More recently, the limitation of the requirements for volatile and other anesthetic agents may be desirable, given concerns regarding the potential impact of these agents on neurocognitive outcome in neonates and infants. Several authors have demonstrated the potential utility of combining a neuraxial technique (spinal or epidural anesthesia) with general anesthesia in neonates and infants undergoing intraabdominal procedures. We review the literature regarding the combined use of neuraxial and general anesthesia in neonates and infants during major abdominal surgery, discuss its potential applications in this population, and review the techniques of such practice.

Anaesthetic consideration for neonatal surgical emergencies

A newborn requires constant vigilance, rapid recognition of the events and swift intervention during anaesthesia. The anaesthetic considerations in neonatal surgical emergencies are based on the physiological immaturity of various body systems, poor tolerance of the anaesthetic drugs, associated congenital disorders and considerations regarding the use of high concentration of oxygen. The main goal is for titration of anaesthetics to desired effects, while carefully monitoring of the cardiorespiratory status. The use of regional anaesthesia has shown to be safe and effective. Advancements in neonatology have resulted in the improvement of the survival of the premature and critically ill newborn babies. Most of the disorders previously considered as neonatal surgical emergencies in the past no longer require immediate surgery due to new technology and new methods of treating sick neonates. This article describes the common neonatal surgical emergencies and focuses on factors that affect the anaesthetic management of patients with these disorders.

Trunk blocks for abdominal surgery

In this review, we discuss the central non-neuraxial regional anaesthesia blocks of the abdomen, including intercostal and intrapleural blocks, rectus sheath and ilioinguinal-iliohypogastric blocks, transversus abdominis plane blocks and paravertebral blocks.

Benefit and risks of local anesthetics in infants and children

Regional anesthesia has become a routine part of the practice of anesthesiology in infants and children. Local anesthetic toxicity is extremely rare in infants and children; however, seizures, dysrhythmias, cardiovascular collapse, and transient neuropathic symptoms have been reported. Infants and children may be at increased risk from local anesthetics compared with adults. Larger volumes of local anesthetics are used for epidural anesthesia in infants and children than in adults. Metabolism and elimination of local anesthetics can be delayed in neonates, who also have decreased plasma concentrations of alpha(1)-acid glycoprotein, leading to increased concentrations of unbound bupivacaine. Most regional anesthetic procedures in infants and children are performed with the patient heavily sedated or anesthetized; because of this, and because a test dose is not a particularly sensitive marker of intravenous injection in the anesthetized patient, detection of intravascular local anesthetic injection is extremely difficult. The same local anesthetics used in adult anesthetic practice are also used in infants and children. Because of its extremely short duration of action, chloroprocaine has been used primarily for continuous epidural techniques in infants and children. The use of tetracaine has generally been limited to spinal and topical anesthesia. Lidocaine (lignocaine) has been used extensively in infants and children for topical, regional, plexus, epidural and spinal anesthesia. The association between prilocaine and methemoglobinemia has generally restricted prilocaine use in infants and children to the eutectic mixture of local anesthetics (EMLA). Because of its greater degree of motor block compared with other long-acting local anesthetics, etidocaine has generally been limited to plexus blocks in infants and children. Mepivacaine has been used for both plexus and epidural anesthesia in infants and children. Because postoperative analgesia is often the primary justification for regional anesthesia in infants and children, bupivacaine, a long-acting local anesthetic, is the most commonly reported local anesthetic for pediatric regional anesthesia. Given the lower toxic threshold of bupivacaine compared with other local anesthetics, the risk-benefit ratio of bupivacaine may be greater than that of other local anesthetics. Two new enantiomerically pure local anesthetics, ropivacaine and levobupivacaine, offer clinical profiles comparable to that of bupivacaine but without its lower toxic threshold. The extreme rarity of major toxicity from local anesthetics suggests that widespread replacement of bupivacaine with ropivacaine or levobupivacaine is probably not necessary. However, there are clinical situations, including prolonged local anesthetic infusions, use in neonates, impaired hepatic metabolic function, and anesthetic techniques requiring a large mass of local anesthetic, where replacement of bupivacaine with ropivacaine, levobupivacaine or (for continuous techniques) chloroprocaine appears prudent.

Modern concepts of paediatric analgesia

Laboratory data, economic pressures, and the wish for humane treatment have been some of the driving forces behind improvements in paediatric pain management. Within the space of 10 years, there have been dramatic changes in the quality of treatment received by children undergoing surgical operations. Moreover, those receiving medical treatment, for example, sickle cell disease, have also benefited from increased experience in pain management. Children receiving care in specialised centres can now expect to benefit from up-to-date techniques of pain management, such as patient-controlled analgesia, nurse-controlled analgesia, and epidural infusions. They will be managed by ward nurses experienced and trained in paediatric pain relief, they will be attended by nurses whose special interest and training is the management of children's pain, and they will be provided with the techniques of analgesia by competent, trained anaesthetic staff. Improved care, with close attention to pain relief, is not only humane, but improves the patient turnaround by enhancing rapid discharge. Further education is required to spread these benefits to children being managed outside highly specialised centres. Not only education, but investment, is needed also to ensure that all children receive a standard of care second to none.

Spinal anaesthesia in newborns: total and free bupivacaine plasma concentration

This study was designed to measure total and free bupivacaine (B) after spinal anaesthesia in newborns and to evaluate a possible influence of adrenaline on B absorption. Twenty-two newborns were randomly allocated to receive either plain B (group 1) or adrenaline added to B (group 2) for spinal anaesthesia. A single blood sample was collected ten min after spinal injection. Total B concentration was found 0.31 +/- 0.17 microgram ml-1 in group 1 and 0.25 +/- 0.09 microgram ml-1 in group 2. Bound B concentration was 0.27 +/- 0.17 microgram ml-1 in group 1 and 0.22 +/- 0.09 microgram ml-1 in group 2. No difference was found between the two groups for these parameters. Albumin but not alpha 1-acid-glyco-protein correlated to age and weight, bound B correlated to alpha 1-acid-glyco-protein but not to albumin. Despite the low plasma concentration of binding proteins in newborns, spinal anaesthesia with B does not result in a high level of free drug. Adrenaline does not have any pharmacological advantage in these patients.