Complications in Pediatric Regional Anesthesia : An Analysis of More than 100,000 Blocks from the Pediatric Regional Anesthesia Network

This is a prospective, observational multi-centre study involving over 20 paediatric centres in the USA participating in the Pediatric Regional Anesthesia Network. The aim of the study is to analyse and measure the incidence of major complications from paediatric regional blocks performed by anaesthetists Data from over 100,000 paeditric regional blocks was analysed. Data was collected on all children aged ≤ 18yrs who received a regional block (peripheral and neuraxial) performed by an anaesthetist, between 2007 and 2015.

Data collected included: Standard demographics, type of block, patient state (awake, sedated, GA etc), technology used to perform the block, use of a test dose, type of LA used +/- catheter insertion (including time and reason for removal). Complications and adverse events associated with the block were also recorded. No data on quality of analgesia or efficacy was collected.

Overall Findings:
Nearly 105,000 blocks were performed on over 91,000 children. One quarter of these were in infants with 1% in neonates. In 2007 neuraxial blocks outnumbered peripheral blocks by 3/1.By 2010 onwards neuraxial and peripheral blocks were performed in equal numbers. The single shot caudal was the commonest block. 93.7% of blocks were placed under general anaesthesia. Neurological complications or severe LA toxicity (i.e. seizure or cardiac arrest) were more common when blocks were placed awake or under sedation, 15.2/10000, (95% CI, 7.8 – 28.4/10,000) compared to under GA, 2.2/10000, (95% CI, 1.5 – 3.4/10,000). This increased risk remained when data was adjusted for age (OR 2.93 (95% CI, 1.34 – 5.52; P<0.01). Surface landmarks were used for 95% of all neuraxial blocks; US or fluoroscopy were used for the remaining 5%. The overall block failure rate was 1.05%. The use of ultrasound for peripheral blocks increased over time. The incidence of neurologic complications with peripheral blocks decreased over time (OR0.60; 95% CI 0.38 – 0.90; P = 0.02) but not severe local anaesthetic systemic toxicity (OR 1.08; CI, 0.21 -5.43; P = 0.9).

Neurologic complications were reported in 25 cases (2.4:10,000; 95% CI, 1.6 – 3.6:10,000). They were more common in children more than 10 years of age, in whom the risk was 7.3:10,000 (95% CI, 5.0 to 10.7:10,000; P <0.01). There was no difference in the risk of neurologic complications comparing neuraxial and peripheral blocks (2:10,000, 95% CI, 1.1 to 3.7:10,000 versus 2.8:10,000, 95% CI, 1.6 – 4.7:10,000 P= 0.43). Although the incidence of neurologic complications for peripheral blocks decreased over time, ultrasound use did not affect the overall risk. Additionally, there was no difference in the risk of a neurologic problem comparing caudal to lumbar or thoracic approaches for neuraxial blocks. There was no difference in neurologic problems when comparing catheter to single-injection blocks (P = 0.47), local anaesthetic type (bupivacaine vs. ropivacaine,( P= 0.09), or local anaesthetic concentration more than 0.25% (P=0.06). Neurologic complications were primarily sensory in nature and resolved over a period of weeks to months, with only two cases demonstrating a sensory deficit beyond 3 months. There were no cases of permanent motor deficit recorded.

Severe local anaesthetic systemic toxicity was reported in 7 cases (0.76:10,000, 95% CI, 0.3 -1.6:10,000). There were 4 cases of cardiac arrest and 3 of seizures. Three cases involved
single-injection caudal blocks. An epinephrine-containing test dose was used in all cases and all cases involved bolus dosing of local anaesthetic. Infants under 6 months old were at significantly greater risk of severe local anaesthetic systemic toxicity than other children (OR 7.42; 95% CI, 1.31-39.25; P = 0.02). ASA class, block type, use of ultrasound or a test dose did not affect the risk of local anaesthetic systemic toxicity. There were 11 additional cases of mild local anaesthetic systemic toxicity reported (mild clinical symptoms or subtle ECG changes). All of these additional cases were reported in the postoperative period, and all symptoms resolved with decreasing the rate of or discontinuing the local anaesthetic infusion.

There was one epidural abscess reported (0.76:10,000, 95% CI 0 – 4.8:10,000) in a 2-month-old who had a lumbar epidural catheter. The child made a full recovery after surgical evacuation of the abscess. There were 92 local cutaneous infections reported in 18,065 continuous catheters (53:10,000, 95% CI, 43 -64:10,000). There was a higher rate of infection reported with neuraxial catheters (60:10,000, 95% CI, 48 – 75:10,000) when compared to peripheral catheters (26:10,000, 95% CI, 15 – 45:10,000; P < 0.01). There was no difference found in risk of infection between caudal and lumbar or between caudal and thoracic catheters. Cases of infection had a significantly longer median catheter duration of 4 days compared to cases without infection, which had a median duration of 2 days (interquartile range, 1 to 3 days; P < 0.01). The risk of infection increased by 6.7% for each additional catheter day (OR 1.067; 95% CI, 1.02 -1.12; P < 0.01). ASA ≥ 3 was also associated with the risk of infection (P < 0.01). Patients received antibiotic therapy in 29 of 92 cases. The remaining cases were treated with removal of the catheter only. There were no infections associated with single-injection blocks.

There were no hematomas reported with neuraxial catheters. There was one haematoma associated with bilateral paravertebral catheters. This was treated conservatively without surgical intervention and the patient made a full recovery.

“Adverse events”
Catheter complications (e.g. dislodgement, occlusion, disconnection), were the most common adverse events occurring in 4% of cases. These catheter events were more common in children under 3 years of age ( P < 0.01). Respiratory depression occurred in 18 cases, all associated with neuraxial catheters (14:10,000, 95% CI, 9 – 22:10,000). The epidural infusion contained opioid in 15 of these cases. All resolved by changing or pausing the infusion. The incidence of unintentional dural puncture in lumbar (86:10,000,95% CI, 66 – 112:10,000) and thoracic (66:10,000, 95% CI, 46 – 95:10,000) epidural needle insertions was not significantly different ( P = 0.29). The dural puncture rate associated with caudal needle insertion was 10:10,000 (95% CI, 7 – 14:10,000), significantly lower than lumbar or thoracic
approaches (P < 0.01). Post-dural puncture headache occurred in 11 (7%) of the dural puncture cases, and 7 of these 11 patients received an epidural blood patch.

Take Home Message / Commentary
This study provides a large amount of good quality data to help inform and guide paediatric anaesthetists and their patients about risks and complications when inserting and managing regional blocks in children of all ages. Although observational in nature the huge data set collected from multiple paediatric centres gives great insight into “real world” clinical practice.
Much of the data is reassuring and confirms what many paediatric anaesthetists suspected; The placement of both neuraxial and peripheral blocks under GA is at least as safe ( if not considerably safer?) in children compared to awake or with sedation.
Although the use of US to guide insertion has led to an increase in the provision of peripheral nerve blocks and probably a subsequent decrease in neuraxial blocks, the assumption that this makes the blocks safer is not wholly supported by this study Fortunately the incidence of neurological injury, particularly significant motor injury is reassuringly small in both neuraxial and peripheral blocks.
LA toxicity remains a rare but serious complication, particularly when bolus doses are given. Use of US and /or test doses would appear to be of little benefit. Given the comprehensive nature of the data analysis in this study the lack of analysis and commentary on the type of LA used and its association with severe or mild LA toxicity is disappointing.
Overall this is an extremely well conducted and written study that I would recommend every paediatric anaesthetist involved in performing and managing regional blocks should take the time to read and consider how it might influence their current and future practice.

Reviewed by: Dr H. Hack