Knee Arthroplasty Anesthesia: PACU Time, Waste, and Item Costs
Key Takeaways
- Among adults undergoing total knee arthroplasty at a Finnish academic hospital, total and non-operative operating-room times did not differ significantly between spinal and general anesthesia.
- Recovery-unit time was significantly longer after spinal anesthesia with sedation.
- Hypotension treatment was more frequent with general anesthesia, while labetalol treatment for hypertension was more frequent with spinal anesthesia.
- General anesthesia generated more than twice as much measured anesthesia-related mixed waste.
- Measured anesthesia medicine and equipment costs were higher with general anesthesia.
At HUS Helsinki University Hospital in Finland, a randomized-trial secondary analysis included 395 adults with Kellgren–Lawrence grade 3–4 knee arthritis: 200 were assigned spinal anesthesia with sedation and 195 total intravenous general anesthesia. The original trial also varied tourniquet use and focused on postoperative opioid consumption. The analysis’s prespecified primary outcome was total operating-room (OR) occupancy, measured from arrival until transfer to the post-anesthesia care unit (PACU). Non-operative OR time covered periods before incision and after closure; PACU time ended when local discharge criteria were met. Investigators recorded timing and interventions from charts and study forms, weighed single-use anesthesia items and medicines with observed additional procedures, and applied institutional purchase prices.
Total and non-operative OR times did not differ significantly by anesthesia assignment. PACU time was significantly longer after spinal anesthesia: the median was 104 minutes (interquartile range, 71–148) versus 73 minutes (49–98) after general anesthesia. The Hodges–Lehmann difference was 32 minutes (95% confidence interval, 23–42).
Vasoactive boluses for hypotension were given to 24% of the spinal group versus 82% of the general group, a significant difference. Noradrenaline infusions were also more frequent with general anesthesia, whereas labetalol boluses for hypertension were more frequent with spinal anesthesia. Clonidine infusion and urinary catheterization did not differ significantly. Per-patient mixed waste, accounting for observed hemodynamic interventions and catheterization, weighed 611 g with spinal versus 1252 g with general anesthesia. The separate protocol-only calculation did not include those additional procedures. Average anesthesia medicine, single-use equipment, and hemodynamic-intervention item costs were €35.72 versus €82.99 per patient, respectively.
These selected patients came from one Finnish center, and neither patients nor staff were blinded. The spinal protocol used 15 mg of bupivacaine; local PACU discharge criteria after regional anesthesia required patients to lift the unoperated leg, which could affect the recovery-time comparison. Item accounting excluded electricity, oxygen, surgical-site items, and upkeep of reusable instruments. Investigators did not measure carbon-dioxide-equivalent emissions or overall pollution severity. The €47.27 per-patient difference in measured item spending is approximately US$50 at an illustrative near-parity conversion, not an estimate of total-care savings. Costs reflected local purchasing, and PACU occupancy does not translate directly into a labor-cost difference.
According to the authors, the anesthetic approaches had similar OR occupancy but different recovery, hemodynamic-intervention, mixed-waste, and anesthesia-item cost patterns in this Finnish setting. The comparison does not establish an overall economic, safety, or carbon-footprint advantage.
Clinician Questions
Which patients were excluded from the Finnish total knee arthroplasty comparison of spinal and general anesthesia?
At HUS Helsinki University Hospital, adults awaiting total knee arthroplasty for Kellgren–Lawrence grade 3–4 knee arthritis were ineligible for the comparison of spinal anesthesia with sedation and total intravenous general anesthesia if they were older than 75 years, had a body mass index of at least 40 kg/m² or an American Society of Anesthesiologists (ASA) class of at least 4, had a contraindication to either anesthetic method or a severe anatomical abnormality of the operative knee, or were undergoing bilateral surgery.
Does shorter PACU time after general anesthesia for knee arthroplasty directly reduce staffing costs?
Not necessarily at the Finnish hospital studied: PACU personnel worked planned hours and cared for several patients simultaneously, so a shorter stay for one total knee arthroplasty patient would not automatically reduce staffing expenditure. Investigators cited avoiding overtime for the day’s last PACU patient as an example of when staffing costs might change.