Effects of an infratrochlear nerve block on reducing the oculocardiac reflex during strabismus surgery: a randomized controlled trial
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To determine whether an infratrochlear nerve block (ITB) can reduce the oculocardiac reflex (OCR) during strabismus surgery on the medial rectus muscle (MR).
This prospective, randomized single-masked study included 60 patients with intermittent exotropia scheduled for unilateral MR resection/lateral rectus recession under general anesthesia. Patients were randomly allocated to receive a regional nerve block of the infratrochlear nerve (ITB group) prior to surgery or standard treatment without a nerve block (control group). The OCR was defined as a sudden decrease in heart rate of ≥ 15% from baseline. Changes in heart rate (HR) and the incidence of the OCR were measured during the three stages of surgery applied to the MR in each group: conjunctival incision, muscle dissection, and muscle traction.
There were no intergroup differences in patient demographics or baseline HR. The mean HRs during conjunctival incision, muscle dissection, and muscle traction were 94, 90, and 96 bpm, respectively, in the ITB group, and 85, 68, and 84 bpm in the control group; the corresponding OCR incidence rates were 3, 20, and 10%; and 7, 87, and 38%. The HR was higher and the OCR incidence was lower in the ITB group than in the control group during muscle dissection and traction (all p < 0.05).
An ITB maintains a stable HR and reduces the OCR during surgery on the MR. The ITB is less invasive and easily accessible to a surgeon, and can help improve the safety of strabismus surgery.
KeywordsInfratrochlear nerve block Medial rectus Oculocardiac reflex Strabismus surgery
SH Kim designed the study and revised the manuscript, and HJ Shin collected and analyzed the data and wrote the manuscript.
This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2016R1C1B1014199). This support had no role in the design or conduct of this study.
Compliance with ethical standards
This clinical study was approved by the Institutional Review Board/Ethics Committee at Konkuk University Medical Center (registration number KUH1100040) and registered with the Clinical Research Information Service, Republic of Korea (https://cris.nih.go.kr/cris/index.jsp; registration number KCT0002378). The study was conducted according to the principles expressed in the Declaration of Helsinki with written informed patient and parental consents.
Conflict of interest
All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge, or beliefs) in the subject matter or materials discussed in this manuscript.
All patients confirmed as American Society of Anesthesiologists physical status classification I. All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee (name the institution/committee) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
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