Effects of Small-Dose S-Ketamine On Anesthesia-Induced Atelectasis In Patients Undergoing General Anesthesia Accessed By Lung Ultrasound: Study Protocol For A Randomized, Double-Blinded Controlled Trial

Abstract

Background: Aelectasis after anesthesia induction in most patients undergoing general anesthesia may lead to postoperative pulmonary complications (PPCs) and affect postoperative outcomes. However, there is still no existing effective method used for the prevention of perioperative atelectasis. S-ketamine may prevent atelectasis due to airway smooth muscle relaxation and anti-inflammatory effects. Lung ultrasound is a portable and reliable bedside imaging technology for diagnosing anesthesia-induced atelectasis. In this study, we aim to assess whether a small dose of S-ketamine can reduce the incidence of atelectasis after intubation under general anesthesia using lung ultrasound, in order to prevent the early formation of perioperative atelectasis and PPCs.Methods: This is a single-institution, prospective, randomized controlled, parallel grouping, and double-blind study. From October 2020 to March 2022, 100 patients (18-60 years old) scheduled for elective surgery will be recruited from Beijing Tiantan Hospital, Capital Medical University, and randomly assigned to the S-ketamine group (Group S) and the normal saline group (Group N) at a ratio of 1:1. The label-masked agents will be administered 5 min before induction, and all patients will undergo a standardized general anesthesia protocol. Related data will be collected at three-time points: after radial artery puncture (T1), 15 min after tracheal intubation (T2), and before extubation (T3). The primary outcome will be the total lung ultrasound scores (LUS) at T2. Secondary outcomes will include LUS in six chest regions at T2, total LUS at T3, arterial blood-gas analysis results (PaCO2, PaO2) and PaO2/FiO2 at T2 and T3, plateau pressure(Pplat) and dynamic lung compliance (Cdyn) at T2 and T3. The incidence of postoperative complications associated with S-ketamine and PPCs at 2 h and 24 h after surgery will be recorded.Discussion: This trial aims to explore whether a simple and feasible application of S-ketamine before the induction of general anesthesia can prevent atelectasis. The results of this study may provide new ideas and direct clinical evidence for the prevention and treatment of perioperative pulmonary complications during anesthesia.Trial registration: ClinicalTrials.gov identifier: NCT04745286.