Phenylephrine Usage During Anesthesia in Concussed Patients Undergoing Orthopedic Surgery: A Retrospective Cohort Study.

Background and objective Concussion can lead to complex physiologic changes, including alterations to cerebral blow flow autoregulation. Based on this understanding, we aimed to analyze if concussed patients undergoing orthopedic surgery required a higher dosage or a more frequent administration of phenylephrine while under general anesthesia; we also sought to assess if a concussion with an associated loss of consciousness (LOC) influenced treatment. Methods We performed a retrospective review of the data of patients admitted in the past three years to the emergency room (ER) with a diagnosis of head concussion at our level-one trauma center. Patients were filtered by selecting those who underwent a single emergent orthopedic surgical procedure under general anesthesia: a total of 61 individuals. We further refined this group according to the presence/absence of LOC. The cohort with concussion coupled with LOC included 50 patients (82% of the treatment group), and the cohort with concussion without LOC had 11 patients (18% of the treatment group). Concussed patients were compared to a matched group of 118 patients without head trauma who also presented to the ER in the same period and required similar emergent orthopedic surgeries during their hospitalization. Phenylephrine was the most common vasopressor used in all surgeries. Statistical analyses involved chi-square tests for the frequency of phenylephrine usage. The Kruskal-Wallis and Dunn's tests were also used to examine differences in phenylephrine dosage across each cohort. Results In all concussed patients, regardless of LOC, there was no difference in phenylephrine usage during general anesthesia compared to controls without head trauma. However, concussed patients who experienced LOC required significantly higher doses of phenylephrine compared to controls.  Conclusions This is the first study to explore the relationship between concussion, LOC, and vasopressor usage during general anesthesia. Its findings demonstrated an increased requirement for phenylephrine in concussed patients with LOC compared to controls.