Neurological and histological outcomes after subarachnoid injection of a liposomal bupivacaine suspension in pigs: a pilot study.

BACKGROUND: An injectable liposomal bupivacaine suspension (EXPAREL™) is approved by the US Food and Drug Administration for analgesia by tissue infiltration and interscalene brachial plexus, but not for use in the neuraxial space. This pilot study describes neurological and histological outcomes of escalating doses of this extended-release formulation of bupivacaine after subarachnoid administration. METHODS: Twenty-five pigs (Sus scrofa domesticus) weighing 36.2 (4.4) kg were randomly assigned to one of five groups to receive a subarachnoid injection of sodium chloride 0.9%, 3 ml (negative control), preservative-free bupivacaine hydrochloride 0.5%, 3 ml (positive control), or one of three doses of liposomal bupivacaine suspension 1.33%: 1.5, 3, or 5 ml. After recovering from general anaesthesia, neurological outcomes were assessed by blinded observers. Three weeks later, the animals were sacrificed for histological evaluations of neurotoxicity. RESULTS: Animals that received sodium chloride 0.9%, bupivacaine hydrochloride, or liposomal bupivacaine 1.5 ml recovered within 2, 5, or 4 h, respectively. Animals that received liposomal bupivacaine 3 or 5 ml exhibited signs of neuraxial block (decreased nociception and proprioception) up to 32 h after injection. No histological evidence of neurotoxicity was found in any of the groups. CONCLUSIONS: Subarachnoid administration of liposomal bupivacaine in pigs exhibited a dose-response effect, and resulted in longer duration of neuraxial block than bupivacaine hydrochloride without histological evidence of neurotoxicity. Our study contributes preliminary data to inform further toxicological assessments and regulatory approval before subarachnoid administration in humans.

A randomised comparison of C-MAC™ and King Vision® videolaryngoscopes with direct laryngoscopy in 180 obstetric patients.

BACKGROUND: Current evidence suggests that there is uncertainty about which videolaryngoscope performs best in obstetric anaesthesia. The aim of this study was to compare C-MAC and King Vision® videolaryngoscopes and direct laryngoscopy for tracheal intubation of patients undergoing caesarean section. METHODS: One hundred and eighty women were randomly assigned. The primary outcome was the time to tracheal intubation. Secondary outcomes were the time to the best laryngeal view, grade of Cormack and Lehane view, overall and first-pass success, intubation difficulty, the number of intubation attempts and optimisation manoeuvres; and complications. RESULTS: The time to successful intubation, first-pass and overall success rates did not differ between the devices. The difficulty of intubation was less for C-MAC than King Vision® (P <0.001). No difference was observed between King Vision® and direct laryngoscopy (P=0.06) or C-MAC and direct laryngoscopy (P=0.05). King Vision® required the longest time to best laryngeal view (9 ±â€¯6 s, P=0.028), had the highest rate of grade 1 view (47 (80%) patients, P <0.001), and the highest need for optimisation manoeuvres (59 (100%) patients, P <0.0001). Five minor complications were recorded with King Vision® and one with direct laryngoscopy. CONCLUSIONS: Compared to direct laryngoscopy, C-MAC and King Vision® did not prolong the time to intubation, supporting these videolaryngoscopes as primary intubation devices in obstetric anaesthesia. The C-MAC was easier to use and needed fewer additional manoeuvres than the King Vision®. The C-MAC may be better suited for tracheal intubation of obstetric patients undergoing caesarean section.

Impact of epidural analgesia on cesarean and operative vaginal delivery rates classified by the Ten Groups Classification System.

BACKGROUND: The Ten Group Classification System (TGCS) allows critical analysis according to the obstetric characteristics of women in labor: singleton or multiple pregnancy, nulliparous, multiparous, or multiparous with a previous cesarean delivery, cephalic, breech presentation or other malpresentation, spontaneous or induced labor, and term or preterm births. Labor outcomes associated with epidural analgesia may be different among the different labor classification groups. The aim of this study was to explore associations between epidural analgesia and cesarean delivery, and epidural analgesia and assisted vaginal delivery, in women classified using the TGCS. METHODS: Slovenian National Perinatal Information System data for the period 2007-2014 were analyzed. All women after spontaneous onset or induction of labor were classified according to the TGCS, within which cesarean and vaginal assisted delivery rates were investigated (P <0.003 significant). RESULTS: Data on 207 525 deliveries (and 211 197 neonates) were analyzed. In most TGCS groups women with epidural analgesia had lower cesarean delivery rates. Women in group 1 (nulliparous term women with singleton fetuses in cephalic presentation in spontaneous labor) with epidural analgesia had a higher cesarean delivery rate. In most TGCS groups women with epidural analgesia had higher assisted vaginal delivery rates. CONCLUSION: Epidural analgesia is associated with different effects on cesarean delivery and assisted vaginal delivery rates in different TGCS groups.

A feasibility study of awake videolaryngoscope-assisted intubation in patients with periglottic tumour using the channelled King Vision® videolaryngoscope.

Airway management in patients with periglottic tumour is a high-risk procedure with potentially serious consequences. There is no consensus on how best to secure the airway in this group of patients. We conducted a feasibility study of awake tracheal intubation using a King Vision® videolaryngoscope with a channelled blade in a cohort of 25 patients, with a periglottic tumour requiring diagnostic or radical surgery. We used 10% and 4% lidocaine to topicalise the airway and midazolam and remifentanil for sedation. We recorded the success rate, number of attempts, time to obtain glottic view, time to intubation and complications. Twenty-three of the 25 patients (92%, 95%CI 75-98%) were intubated with the awake videolaryngoscope-assisted technique, with 17/23 (74%, 95%CI 54-87%) intubations achieved at the first attempt. Five patients required two and one patient, three attempts at intubation. Two patients (8%, 95%CI 2-25%) could not tolerate the procedure due to inadequate topical anaesthesia. Median (IQR [range]) times to obtain glottic view and to intubate were 19 (17-22 [10-30]) s and 49 (42-71 [33-107]) s, respectively. Traces of blood in the airway were observed in 4/25 (16%, 95%CI 6-35%) patients. Although airway management in this group of patients was expected to be difficult, successful awake intubation with the King Vision videolaryngoscope was achieved in the majority of patients within less than a minute. This study highlights a number of potential advantages of awake videolaryngoscope-assisted intubation over other awake methods of securing the airway in patients with upper airway obstruction due to periglottic mass.

Neurotoxicity of perineural vs intraneural-extrafascicular injection of liposomal bupivacaine in the porcine model of sciatic nerve block.

Liposomal bupivacaine is a prolonged-release local anaesthetic, the neurotoxicity of which has not yet been determined. We used quantitative histomorphometric and immunohistochemical analyses to evaluate the neurotoxic effect of liposomal bupivacaine after perineural and intraneural (extrafascicular) injection of the sciatic nerve in pigs. In this double-blind prospective randomised trial, 4 ml liposomal bupivacaine 1.3% was injected either perineurally (n = 5) or intraneurally extrafascicularly (n = 5). Intraneural-extrafascicular injection of saline (n = 5) was used as a control. After emergence from anaesthesia, neurological examinations were conducted over two weeks. After harvesting the sciatic nerves, no changes in nerve fibre density or myelin width indicative of nerve injury were observed in any of the groups. Intraneural injections resulted in longer sensory blockade than perineural (p < 0.003) without persistent motor or sensory deficit. Sciatic nerve block with liposomal bupivacaine in pigs did not result in histological evidence of nerve injury.

The utility of three-dimensional optical projection tomography in nerve injection injury imaging.

The examination of nerve microarchitecture has hitherto been limited solely to two-dimensional imaging techniques. The objective of this study was to evaluate the ability of optical projection tomography to discern the nerve microarchitecture and injection injury in three dimensions. Five piglets were studied, whose median and lingual nerves were unilaterally injected post mortem with preset volumes of local anaesthetic, excised and subsequently made transparent with benzyl alcohol benzyl benzoate. Images were captured in three dimensions. The same contralateral nerves were used as controls. Using optical projection tomography, we observed differences between the internal organisation of the median and the lingual nerves, which potentially explain the variations in their susceptibility to injury. This was demonstrated in three dimensions as a disruption to the fascicles in the lingual nerve, and their displacement in the median nerve. This new technology offers potential for studying nerve microarchitecture topography and its tolerance to injection injury.