The Hidden Risks of Perioperative Transfusions in Traumatic Lower Extremity Free Flap Reconstruction.

BACKGROUND: Blood transfusions have been associated with surgical complications; however, these studies are not specific to lower extremity (LE) reconstruction. We evaluated the effect of perioperative packed red blood cell (PRBC) transfusions on LE free flap outcomes in trauma patients. METHODS: Patients undergoing LE free flap reconstruction following acute injuries from 2016 to 2021 were retrospectively analyzed. The perioperative period for transfusions was defined as ± 3 days from the procedure. Parameters included demographics, perioperative characteristics, and outcomes. Major complications were complications requiring reoperation. Univariate and multivariate analyses were performed to identify associations. RESULTS: Of the 205 patients, 48% received PRBCs perioperatively. There was a trend toward higher major complications rate in the transfusion group (19 vs. 10%, p = 0.09). Wound size, injury severity score (ISS), and intraoperative estimated blood loss were greater in the transfusion group (p < 0.01). Preoperative hemoglobin/hematocrit were lower in the transfusion group (p < 0.001). Units of PRBCs transfused were independently associated with major complications on multivariate analysis (odds ratio [OR] = 1.34, confidence interval [CI]: 1.06-1.70, p = 0.015) and length of hospital stay (LOS; OR = 1.05, CI: 1.02-1.08, p = 0.002). Infection, wound size, ISS, and preoperative hemoglobin/hematocrit were independently associated with increased LOS (p < 0.05) but not with major complications. CONCLUSION: The number of units of PRBCs given perioperatively was the only variable independently associated with major complications on multivariate analysis and was one of many variables associated with increased LOS. These findings suggest the usage of restrictive transfusion protocols in trauma patients requiring LE reconstruction.

Superior colliculus bidirectionally modulates choice activity in frontal cortex.

Action selection occurs through competition between potential choice options. Neural correlates of choice competition are observed across frontal cortex and downstream superior colliculus (SC) during decision-making, yet how these regions interact to mediate choice competition remains unresolved. Here we report that SC can bidirectionally modulate choice competition and drive choice activity in frontal cortex. In the mouse, topographically matched regions of frontal cortex and SC formed a descending motor pathway for directional licking and a re-entrant loop via the thalamus. During decision-making, distinct neuronal populations in both frontal cortex and SC encoded opposing lick directions and exhibited competitive interactions. SC GABAergic neurons encoded ipsilateral choice and locally inhibited glutamatergic neurons that encoded contralateral choice. Activating or suppressing these cell types could bidirectionally drive choice activity in frontal cortex. These results thus identify SC as a major locus to modulate choice competition within the broader action selection network.

Superior colliculus cell types bidirectionally modulate choice activity in frontal cortex.

Action selection occurs through competition between potential choice options. Neural correlates of choice competition are observed across frontal cortex and downstream superior colliculus (SC) during decision-making, yet how these regions interact to mediate choice competition remains unresolved. Here we report that cell types within SC can bidirectionally modulate choice competition and drive choice activity in frontal cortex. In the mouse, topographically matched regions of frontal cortex and SC formed a descending motor pathway for directional licking and a re-entrant loop via the thalamus. During decision-making, distinct neuronal populations in both frontal cortex and SC encoded opposing lick directions and exhibited push-pull dynamics. SC GABAergic neurons encoded ipsilateral choice and glutamatergic neurons encoded contralateral choice, and activating or suppressing these cell types could bidirectionally drive push-pull choice activity in frontal cortex. These results thus identify SC as a major locus to modulate choice competition within the broader action selection network.