Effect of Lidocaine, Dexmedetomidine, Esmolol and Magnesium Use on Optic Nerve Sheath Diameter and Hemodynamic Response After Laryngoscopy: Randomized, Controlled, Double-blind Trial

Laryngoscopy and endotracheal intubation could have detrimental effects on patients with limited physiologic reserve to cope with the possible hemodynamic alterations caused by the sympathoadrenal response. Although it is known to be a short-lasting and reversible physiological alteration, it could lead to more profound destructive effects, especially in patients with possible elevated intracranial pressure, such as in multi-trauma or intracranial hemorrhage. Therefore, minimizing alterations due to general anesthesia induction and intubation has been essential to optimize qualified critical patient management. Various drugs through different routes have been studied, focusing on hemodynamic alterations. However, as the health services and capabilities of the anesthesiologists improve, changes in outcome measures, such as intracranial pressure, could be observed directly by the integration of optic nerve ultrasonography (ONUS) as a part of point of care ultrasonographic (POCUS) examination. Notably, the measurement of optic nerve sheath diameter (ONSD) has been proven to be related to intracranial pressure, and several studies have even presented cut-off values with high diagnostic accuracy for increased intracranial pressure. Therefore, investigating ONSD during endotracheal intubation is a non-invasive, time and cost-effective method to observe the precise effects of drugs that can establish stability during intubation.

In this study, a wide variety of drugs from previous literature, lidocaine, dexmedetomidine, esmolol, and magnesium, has been chosen for their possible effectiveness in abolishing hemodynamic response to laryngoscopy. The study aims to compare the direct effect of these alternatives on ONSD during endotracheal intubation with concomitant hemodynamic changes. This study would like to emphasize POCUS and support the incorporation of ONUS as a valuable practice to improve general anesthesia management for fragile patients.

METHODS The trial design is a double-blind, randomized controlled study with the approval of our Institutional ethics committee (dossier no: 106-2021). The participants were assessed within patients scheduled for any elective surgery needing endotracheal intubation after January 2024 for eligibility. After obtaining written informed consent, 100 patients (Five groups; 1:1 distribution; n=20) were allocated, and the study was conducted in a tertiary care hospital with the principles outlined in the Helsinki Declaration.

Patients eligible for inclusion in this study are those aged 18 to 80 years who have undergone endotracheal intubation for general anesthesia and have an American Society of Anesthesiologists (ASA) Physical Status classification of I to III.

Patients are excluded if they had one of the following criteria: Patients allergic to dexmedetomidine, esmolol, lidocaine, magnesium; patients with uncontrolled hypertension or advanced heart failure with EF below 35%; patients with cardiac arrhythmia, especially Type 2 and 3 blocks, supraventricular arrhythmias, patients with renal failure (GFR below 30) or severe liver failure; patients with known acute or previous intracranial pathology and known diagnosis of epilepsy, predefined complex airway examination, patients who required more than one attempt at intubation or total laryngoscopy took more than 20 s.