2025 FSA Podium and Poster Abstracts

Introduction: Propofol total intravenous anesthetics (TIVA) are a common modality designed to prevent the development of postoperative nausea and vomiting (PONV) in high-risk patients. While this modality is a safe and effective alternative to inhalational anesthetics, prolonged propofol infusions can have some notable side effects. This case reports on a patient undergoing a propofol TIVA for breast surgery who developed mysteriously white cloudy urine five hours into her anesthetic.

Methods: A 53-year-old 74 kg ASA 3 female with PMH of severe PONV, hypertension, angina, anxiety, gastric reflux, and recently diagnosed left breast ductal carcinoma in situ presented to an ambulatory surgery center for her bilateral mastectomy and reconstruction. Prior to the procedure, a transdermal scopolamine patch was placed, and the patient received bilateral T2-T7 paravertebral blocks using 50 mL total of 0.3% diluted ropivacaine. An opioid free anesthetic was planned for the patient, including 4 mg midazolam for anxiolysis and induction with 20 mg ketamine, 100 mg lidocaine, 110 mg propofol, and 50 mg rocuronium. After successful intubation, the patient was maintained with the assistance of a bispectral index monitor using a propofol infusion at rates between 150-250 mcg/kg/min. For the prevention of PONV, the patient was also administered 4 mg dexamethasone and 150 mg fosaprepitant at the beginning of the procedure.

Results: Approximately five hours after starting the propofol infusion, the patient’s previously clear yellow urine had turned cloudy yellow (Figure 1). Up until that point, the patient had received roughly 1 liter of normal saline and had 650 mL of urine output. After verifying the patient’s continued hemodynamic stability (requiring no vasoactive medications during the case) and ventilator settings including a normal end-tidal CO2, an additional 250 mL fluid bolus was administered. A sample of this urine was mixed with 25 mEq of sodium bicarbonate, which alkalinized the urine and turned it clear (Figure 2). With the presumptive diagnosis of uric acid precipitation and the completion of the procedure nearing, the patient was administered 4 mg of ondansetron and successfully awoken from the anesthetic. In the PACU, the patient denied any nausea or vomiting, and she was advised to continue oral hydration due to her urinary crystal precipitation.

Conclusions: Propofol has been safely utilized as a sedative and anesthetic agent for many years, but does cause the feared complication of propofol infusion syndrome. This syndrome is associated with propofol infusions over 70 mcg/kg/min for over 24 hours and presents with hypertriglyceridemia, pancreatitis, metabolic acidosis, and green urine. While this case lasted only six hours, the appearance of cloudy white urine on high dose propofol infusion for TIVA was concerning. Although not commonly known, propofol is a competitive antagonist of urate transporter URATE1, leading to decreased urate resorption and increased urinary urate, which can easily precipitate in the acidic environment of the urine. With this easy beside alkalinization of the cloudy urine, the anesthesia staff and patient were reassured of this benign finding following a successful TIVA for the prevention of PONV during mastectomy and breast reconstruction surgery.