Direct Comparison of Peak Bulk Flow Rate of Programmable Intermittent Epidural Bolus and Manual Epidural Bolus Using a Closed-End Multiorifice Catheter: An Experimental Study

Abstract

BACKGROUND:The programmable intermittent epidural bolus (PIEB) has been popularized as the optimal delivery technique for labor analgesia. Suggested advantages of this method are less local anesthetic consumption, improved maternal satisfaction, potentially shorter duration of labor, and decreased workload requirements for the anesthesia providers. However, a manual bolus is still routinely used for breakthrough pain when the PIEB is underperforming. METHODS: We conducted a laboratory-based study to quantify the flow through a multiorifice epidural catheter using the PIEB setting on an epidural pump compared to the manual epidural bolus. Four syringe volumes, 3, 5, 10, and 20 mL, were selected for this experiment. The flow in a manual bolus was also studied with and without the presence of an epidural catheter filter. A generalized estimating equation analysis was done to compare data between the groups. RESULTS: Regardless of the syringe size, there was a several-fold increase in flow when a manual bolus was used compared to a pump-administered dose, with the highest difference in the peak flow rate observed in 3-mL boluses with up to a 12-fold difference, while the difference was, at most, 7-fold in 5-mL and 10-mL boluses. Manual boluses without a filter achieve a mean peak flow rate higher than manual boluses with a filter. CONCLUSIONS: Our study found that manual boluses produced a higher flow rate compared to the CADD-Solis epidural pump (Smiths Medical). This study also found that the placement of a particulate filter reduces the flow rates generated while bolusing. Bulk flow rate is directly correlated with induced pressure and solution spread. Because higher bolus pressure has been shown to provide a more efficient distribution of local anesthetic and more efficient pain relief, these results may have impactful clinical significance and will pave the way for future studies.

Comparison of Peak Bulk Flow Rate of Programmable Intermittent Epidural Bolus and Manual Epidural Bolus Using a Closed-End Multiorifice Catheter

“…We are writing to raise some concerns about the study conducted by Younger et al 1 Their article, “Direct Comparison of Peak Bulk Flow Rate of Programmable Intermittent Epidural Bolus and Manual Epidural Bolus Using a Closed-End Multiorifice Catheter: An Experimental Study,” demonstrated that manual boluses produced a higher flow rate compared to programmed intermittent epidural bolus (PIEB) administration at the rate of 250 mL/h.…”

In Response

“…In this regard, the use of hyperbaric drugs, namely bupivacaine, could have an even better profile. These could allow a more judicious titration of the local anesthetic dose, 2 also minimizing the appearance of hypotension, the time to reversal of motor blockade, and the stay in the postanesthesia care unit, without reducing the duration of analgesic effects 3 or the degree of muscle relaxation, 4 compared to the more sensory blockade profile provided by ropivacaine.…”

“…The main objective of the current study was to evaluate the efficacy of PIEB relative to manual boluses. 3 However, we propose that the investigation of pressure values at the epidural catheter's distal portion would be significantly more important for any future benchtop studies investigating safety concerns regarding epidural bolus.…”