Key result
Epidural lidocaine increases hepatic blood flow vs saline in dogs despite lower mean arterial pressure.
Why the study?
General anesthesia reduces hepatic blood flow through circulatory depression, prompting investigation into whether thoracolumbar epidural anesthesia combined with total intravenous anesthesia could improve hepatic blood flow.
Does thoracolumbar epidural anesthesia with lidocaine improve hepatic blood flow in propofol-anesthetized dogs?
RCT (n=6)
Randomized crossover
No
Does thoracolumbar epidural anesthesia with lidocaine improve hepatic blood flow in propofol-anesthetized dogs?
p-value: p=<0.01
Thoracolumbar epidural anesthesia with lidocaine maintains or increases hepatic blood flow in propofol-anesthetized dogs despite decreasing mean arterial pressure.
May support epidural lidocaine to preserve hepatic perfusion in anesthetized dogs; hypothesis-generating, should not change practice.
General anesthesia reduces hepatic blood flow (HBF) from circulatory depression. Total intravenous anesthesia (TIVA) is associated with decreased circulatory depression compared to inhalation anesthesia, and epidural anesthesia using local anesthetics increases blood flow by blocking the sympathetic nerves and expanding blood vessels. We investigated the effects of thoracolumbar epidural anesthesia with TIVA on HBF in dogs. Six Beagle dogs had epidural catheters placed between T13 and L1 and were anesthetized with propofol and vecuronium. Physiological saline (control) or 2% lidocaine (0.2 ml/kg, followed by 0.2 ml/kg/hr) was administered at 1-2 weeks intervals. Heart rate (HR), cardiac index (CI), mean arterial pressure (MAP), and systemic vascular resistance index (SVRI) were recorded at 10-min intervals from before epidural injections (T0) to 110 min. Indocyanine green test was used to measure HBF during the awake state and until 90 min after epidural injections. HR and CI did not differ between treatments. MAP and SVRI after lidocaine were significantly lower than those of controls, and the lowest MAP value was 65 ± 11 mmHg at T10. Compared to T0, after lidocaine treatment, HBF was significantly higher at T30, T60 and T90 (P<0.05); while, after control treatment, no significant change was evident at any time point. Despite a decrease in MAP by this technique, HBF was either maintained at pre-anesthetic levels or increased in comparison to controls, probably due to vasodilation of the hepatic artery induced by the selective blockade sympathetic ganglia.
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Iseri et al. (2021) conducted an RCT in Healthy dogs under general anesthesia (n=6). Thoracolumbar epidural anesthesia with lidocaine vs. Physiological saline was evaluated on Hepatic blood flow (indocyanine green plasma clearance rate) (p=<0.01). Thoracolumbar epidural anesthesia with lidocaine significantly increased hepatic blood flow compared to saline control in propofol-anesthetized dogs (p<0.01), despite a moderate decrease in mean arterial pressure.
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