An observational cohort study of the meniscus test to detect intravascular epidural catheters in pregnant women

Loss-of-Resistance Versus Dynamic Pressure-Sensing Technology for Successful Placement of Thoracic Epidural Catheters: A Randomized Clinical Trial

BACKGROUND

The traditional loss-of-resistance (LOR) technique for thoracic epidural catheter placement can be associated with a high primary failure rate. In this study, we compared the traditional LOR technique and dynamic pressure-sensing (DPS) technology for primary success rate and secondary outcomes pertinent to identifying the thoracic epidural space.

METHODS

This pragmatic, randomized, patient- and assessor-blinded superiority trial enrolled patients ages 18 to 75 years, scheduled for major thoracic or abdominal surgeries at a tertiary care teaching hospital. Anesthesiology trainees (residents and fellows) placed thoracic epidural catheters under faculty supervision and rescue. The primary outcome was the success rate of thoracic epidural catheter placement, evaluated by the loss of cold sensation in the thoracic dermatomes 20 minutes after injecting the epidural test dose. Secondary outcomes included procedural time, ease of catheter placement, the presence of a positive falling meniscus sign, early hemodynamic changes, and unintended dural punctures. Additionally, we explored outcomes that included number of attempts, needle depth to epidural space, need for faculty to rescue the procedure from the trainee, patient-rated procedural discomfort, pain at the epidural insertion site, postoperative pain scores, and opioid consumption over 48 hours.

RESULTS

Between March 2019 and June 2020, 133 patients were enrolled; 117 were included in the final analysis (n = 57 for the LOR group; n = 60 for the DPS group). The primary success rate of epidural catheter placement was 91.2% (52 of 57) in the LOR group and 96.7% (58 of 60) in the DPS group (95% confidence interval [CI] of difference in proportions: -0.054 [-0.14 to 0.03]; P = .264). No difference was observed in procedural time between the 2 groups (median interquartile range [IQR] in minutes: LOR 5.0 [7.0], DPS 5.5 [7.0]; P = .982). The number of patients with epidural analgesia onset at 10 minutes was 49.1% (28 of 57) in the LOR group compared to 31.7% (19 of 60) in the DPS group ( P = .062). There were 2 cases of unintended dural punctures in each group. Other secondary or exploratory outcomes were not significantly different between the groups.

CONCLUSIONS

Our trial did not establish the superiority of the DPS technique over the traditional LOR method for identifying the thoracic epidural space ( Clinicaltrials.gov identifier: NCT03826186).

Epidural test dose in obstetric patients: should we still use it?

PURPOSE OF REVIEW

As the application of a test dose after epidural catheter insertion in obstetrics has recurrently been associated with serious adverse events affecting both maternal and foetal outcomes, the question whether to test or not remains a controversial issue.

RECENT FINDINGS

Present guidelines do not provide clear recommendations in this regard and several recent surveys indicate a heterogeneity in clinical routine.

SUMMARY

Physiological alterations during pregnancy and labour restrict the use and also the validity of traditional test agents. Epinephrine is not appropriate to detect a vascular insertion in labour and the application of a local anaesthetic test dose may lead to dose-dependent fatal consequences should the catheter be intrathecal, due to an increased sensitivity in parturients. Given the current practice of opioid-amended-low-concentration epidurals, the waiving of a test dose results at worst in a failed epidural, a stark contrast to the potentially severe to fatal complications of a 'traditional' test dose. Hence, an originally preventive measure providing potentially more harm than the consequences of the situation aimed to prevent, should not be recommended. A simple fractionated administration of the initial analgesic dose seems reasonable though.