Authors: Bennion N et al.
Anesthesia & Analgesia. 141(6):1230–1233, December 2025.
Summary
This prospective, single-center observational cohort study evaluated the effectiveness and safety of administering propofol and remifentanil as a combined single-syringe total intravenous anesthesia (TIVA) technique. While standard practice typically uses separate infusion pumps, this institution has employed a single-syringe approach for more than 25 years, despite its off-label status. The study aimed to determine whether this method reliably maintains adequate hypnotic depth as measured by processed electroencephalography (pEEG) during outpatient orthopedic surgery.
A total of 109 adult patients undergoing elective orthopedic procedures received single-syringe propofol–remifentanil TIVA. The combined solution contained propofol 10 mg/mL and remifentanil 20 µg/mL, delivered via a horizontal syringe pump to avoid drug separation. Hypnotic depth was monitored using the Patient State Index (PSi), with adequate hypnosis defined as values between 25 and 50. The primary outcome was the percentage of maintenance anesthesia time spent within this target range.
The technique performed better than hypothesized. The median proportion of maintenance time with PSi values between 25 and 50 was 96%, and 77% of patients maintained target hypnosis for at least 70% of the anesthetic duration. Time spent outside the target range was minimal, with very little oversedation or inadequate hypnosis. Importantly, there were no cases of intraoperative awareness.
Hemodynamic stability was comparable to other anesthetic techniques. Forty-three percent of patients required vasoactive agents, and 14% experienced mean arterial pressure below 65 mm Hg for more than 15 minutes. Postoperative outcomes were favorable, with low rates of nausea and vomiting (8%) and postoperative delirium (6%), none of which persisted beyond the first postoperative day.
Overall, the findings support that single-syringe propofol–remifentanil TIVA can reliably maintain adequate hypnosis and autonomic control when administered carefully with pEEG guidance. The authors note that variability in infusion rates likely reflected differences in patient characteristics, anesthetic sensitivity, and provider practice. They emphasize the need for further studies to assess generalizability and to develop standardized protocols.
Key Points
Single-syringe propofol–remifentanil TIVA maintained adequate hypnotic depth for most of the anesthetic duration.
The majority of patients spent minimal time outside the target pEEG range, with no intraoperative awareness.
Hemodynamic stability and vasoactive agent use were comparable to other anesthetic techniques.
Postoperative nausea, vomiting, and delirium rates were low and transient.
This long-standing off-label technique appears feasible and effective when guided by processed EEG monitoring.
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