Influence of head flexion on intraocular pressure, cardiovascular, and respiratory responses in patients undergoing cataract surgery after endotracheal intubation

Background: In cataract surgery, the periorbital area is prepared and draped after induction of general anesthesia and endotracheal intubation (ETI). For this purpose, the patient’s head and neck is usually flexed 30 to 45 degrees. Neck flexion causes displacement of the endotracheal tube tip toward the carina. Stimulation of the tracheal mucosa may cause bucking, increased intraocular pressure (IOP), laryngospasm and/or bronchospasm, during light anesthesia. Laryngeal constriction and all components of the tracheal response may affect end-tidal carbon dioxide pressure (PETCO2) and peripheral arterial hemoglobin oxygen saturation (SpaO2). Thus, in the current study, we investigated the influence of head and neck flexion on heart rate (HR), systolic and diastolic blood pressure (SAP and DAP), SpaO2, PETCO2, and IOP in patients undergoing cataract surgery with endotracheal intubation during general anesthesia. Patients and Methods: The present prospective study comprised patients aged from 40 to 80 year with 106 American Society of Anesthesia (ASA) physical status I and II. Anesthesia was induced with thiopental sodium, lidocaine and fentanyl. Atracurium 0.5 mg/kg was administered to facilitate tracheal intubation. HR, SAP, DAP, SpaO2, PETCO2, and IOP were measured at 1, 2, and 5 minutes after head flexion. Results: Mean SAP, DAP, IOP, and HR was increased after ETI and head flexion compared with baseline values. PETCO2 and SpaO2 were decreased after ETI and at 1, 2 minutes after head flexion compared with baseline values. Conclusion: In patients undergoing cataract surgery during general anesthesia, endotracheal tube movement caused changes in head and neck position resulting in significant effects on heart rate, systolic and diastolic blood pressures, laryngeal reflexes, SpaO2, PETCO2, and intraocular pressure.