Success of bedside ultrasound to identify puncture site for spinal anesthesia in neonates and infants

Ultrasound-guided spinal anesthesia in infants: a narrative review

BACKGROUND/IMPORTANCE

Infant spinal anesthesia has many potential benefits. However, the delivery of infant spinal anesthesia is technically challenging. The landmark-based technique has not changed for over a century. Advancements in ultrasound technology may provide an opportunity to improve infant spinal procedures.

OBJECTIVE

Our primary objective is to conduct a comprehensive review of the current literature on ultrasonography for spinal anesthesia in infants. Given the narrow scope of this topic, our secondary objective is to review the current literature on ultrasonography for lumbar puncture in infants.

EVIDENCE REVIEW

We reviewed all papers related to the use of ultrasound for infant spinal anesthesia. Two large databases were searched with key terms. Eligibility criteria were full-text articles in English. For our secondary objective, we searched one large database for key terms relating to ultrasonography and infant lumbar puncture. Eligibility criteria were the same.

FINDINGS

Our primary search retrieved six articles. These consisted of four review articles, one case report, and one retrospective observational study. Our secondary search retrieved fourteen articles. These consisted of five randomized control trials, four prospective studies, three retrospective studies, and two review papers.

CONCLUSIONS

Ultrasound yields high-quality images of the infant spine. Most literature regarding ultrasound for infant spinal procedures arises from emergency medicine or interventional radiology specialties. The literature on ultrasound for infant spinal anesthesia is extremely limited, but shows promise. Future studies are needed in order to determine whether ultrasound can improve the success rate for delivery of infant spinal anesthesia.

Manual Palpation versus Ultrasound to Identify the Intervertebral Space for Spinal Anesthesia in Infants

Purpose

Awake spinal anesthesia continues as an alternative to general anesthesia for infants. Standard clinical practice includes the manual palpation of surface landmarks to identify the desired intervertebral space for lumbar puncture (LP). The current study investigates the accuracy of manual palpation for identifying the intended intervertebral site for LP, using ultrasonography for confirmation and to determine the interspace where the conus medullaris ends.

Patients and Methods

After informed parental consent, patients less than one year of age undergoing spinal anesthesia for lower abdominal, urologic, or lower extremity surgical procedures were included. Patients were held in the seated position and an attending pediatric anesthesiologist or pediatric anesthesiology fellow declared the vertebral interspace intended for needle insertion, palpated surface landmarks, and placed a mark at the site. A research anesthesiologist then determined the actual vertebral interspace of the marked site and the location of the conus medullaris using ultrasonography. The time to complete both techniques (manual palpation and ultrasonography) was recorded.

Results

The study cohort included 50 infants (median age of 7 months). Sixteen vertebral interspaces (32%) were inaccurately marked. One was marked two spaces higher than intended, ten were marked one space higher than intended, and five were marked one space lower than intended. In one patient, the intended vertebral interspace for the lumbar puncture overlaid the conus medullaris. The median time required was 25 seconds (IQR 14.3, 32) for palpation and 39 seconds (IQR 29, 63.8) for ultrasonography.

Conclusion

Manual palpation of surface landmarks to determine the correct interspace for LP for spinal anesthesia in infants is inaccurate. The time required to perform spinal ultrasonography in infants for determination of the optimal site for LP is brief and may be useful in ensuring accurate identification of the correct interspace and the location of the conus medullaris.

Local anesthetic systemic toxicity in children: a review of recent case reports and current literature

BACKGROUND

Local anesthetic systemic toxicity (LAST) in children occurs at an estimated rate of 8 per 100 000 blocks (95% CI 0.3 to 1.6). Due to the potential lethality of this iatrogenic complication, a better clarity of risk factors, clinical presentation, and prognosis may be clinically useful for contemporary treatment and prevention.

METHODS

An extensive literature search and detailed analysis of reported cases of LAST in patients less than 18 years of age published between April 2014 and August 2019 was performed. Clinical patterns were summarized.

RESULTS

Thirty-two cases of LAST were described in 17 published articles and 2 additional cases reported to lipidrescue.org, for a total of 34 cases. Three patients did not meet the inclusion criteria. Thirty-one cases were included in the analysis.

DISCUSSION

Infants represented a disproportionately large number of reports of LAST. The majority of local anesthetic doses were within currently published guidelines. Among the reported cases, penile and caudal blocks were the most commonly associated with LAST. Needle aspiration and test dosing with epinephrine failed to predict LAST with certainty. When LAST presented with severe cardiac compromise, intravenous lipid emulsion was given within 10 min in 43% of cases (13 of 30 reported cases). The vast majority of children were under general anesthesia when local anesthetic medications were administered. In children under general anesthesia, LAST presented with cardiac manifestations in 90% of cases (19 of 21 cases). There were no deaths or long-term morbidity reported.

Cervical Epidural and Subarachnoid Catheter Placement in Standing Adult Horses

Horses underwent either cervical epidural space (CES) catheterization or subarachnoid space (SAS) catheterization while restrained in stocks, under deep sedation (detomidine and morphine) and local anesthesia (mepivacaine 2%) block. Catheters were placed under ultrasound guidance with visualization of the dura, SAS, and spinal cord between the first (C1) and second (C2) cervical vertebrae. Following sedation and sterile skin preparation, operator 1 placed under ultrasound guidance, a 6- or 8-inch Tuohy needle with the bevel oriented caudally. For CES, a 6-inch Touhy needle was used with the hanging drop technique to detect negative pressure, and operator 2 then passed the epidural catheter into the CES. For SAS, following puncture of the dura, cerebrospinal fluid (CSF) was aspirated prior to placement of the epidural catheter. Placement into either CES or SAS was confirmed with plain and contrast radiography. Catheters were wrapped for the duration of the study. CSF cytology was assessed up to every 24 h for the study period. Horses were assessed daily for signs of discomfort, neck pain, catheter insertion site swelling, or changes in behavior. A complete postmortem assessment of the spinal tissues was performed at the end of the study period (72 h). Two horses had CES catheters and five horses had SAS catheters placed successfully. All horses tolerated the catheter well for the duration of the study with no signs of discomfort. Ultrasound was essential to assist placement, and radiography confirmed the anatomical location of the catheters. CSF parameters did not change over the study period (P > 0.9). There was evidence of mild meningeal acute inflammation in one horse and hemorrhage in another consistent with mechanical trauma. Placement of an indwelling CES or SAS catheter appears to be safe, technically simple, and well tolerated in standing sedated normal horses.

A Review of Regional Anesthesia in Infants

Regional anesthesia provides effective anesthesia and pain relief in infants with age-specific data attesting to safety and efficacy. Regional anesthesia decreases exposure to opioids and general anesthetic agents and associated adverse drug effects, suppresses the stress response, and provides better hemodynamic stability compared to general anesthesia. Regional anesthesia can prevent long-term behavioral responses to pain. As a result, the overall number and variety of nerve blocks being used in infants is increasing. While neuraxial blocks are the most common blocks performed in infants, the introduction of ultrasound imaging and a better safety profile has advanced the use of peripheral nerve blocks. Infant-specific pharmacokinetic and pharmacodynamic data of local anesthetic medications are reviewed including risk factors for the accumulation of high serum levels of unbound, pharmacologically active drug. Bupivacaine accumulates with continuous infusion and 2-chloroprocaine can be used as an alternative. Local anesthetic systemic toxicity has the highest incidence in infants less than 6 months of age and is associated with bolus dosing and penile nerve blocks. Local anesthetic toxicity is treated by securing the airway, suppression of seizure activity and implementation of cardiopulmonary resuscitation. Administration of intralipid (intravenous lipid emulsion) is initiated at the first sign of toxicity. A high level of expertise in regional anesthesia is needed when treating infants due to their unique development.