Preoperative oral gabapentin with tracheal intubation: influence on intraocular pressure changes in clinically normal dogs

  Background: Maintaining intraocular pressure sensitivity during or during sedation or general anesthesia or maintenance has been the subject of human and animal research. For all patients with eye diseases, an appropriate anesthesia plan should include not only drug selection, but also a preoperative treatment plan to provide the best postoperative results. Due to the sharp increase in intraocular pressure associated with anesthetics and oral endotracheal intubation, patients may experience corneal perforation lesions or glaucoma. Compared with dogs caused by propofol anesthesia, intraocular pressure increased significantly after intubation. Gabapentin is a widely used anti-epileptic drug used to treat epilepsy in humans and dogs. Gabapentin is a suitable drug that can help prevent intraocular pressure from rising during tracheal intubation. The effect of gabapentin on changes in intraocular pressure in dogs after tracheal intubation has not yet been published. The purpose of this study was to investigate the effect of gabapentin on changes in intraocular pressure in dogs after tracheal intubation.

  Method: Before the examination, the intraocular pressure and fundus of the dog should be checked under a microscope and a tonometer to ensure that there is no obvious abnormality in the dog's eye examination. The study included 20 healthy adult dogs. These dogs fasted overnight, but could drink at will. The dogs were randomly divided into treatment group (n = 10) and control group (n = 10). The treatment group received gabapentin (50 mg/kg) 2 hours before surgery. The control group also took oral gelatin capsule placebo. Five minutes after preoxygenation, the dog was anesthetized with propofol (6 mg/kg IV), and anesthesia was maintained at a constant rate of 0.2 mg/kg/min by intravenous infusion for 20 minutes. IOPS is measured immediately before induction (baseline, TB), and repeated immediately after induction (T0) and 5 minutes after tracheal intubation (T5), 10 minutes (T10) and 15 minutes (T15). .. All dogs are measured by the same person. During the measurement, the animal was placed in a normal upright position with the head of the sternum lying flat, and the eyelids were not manipulated. Before the measurement, apply 1 drop of streptomycin hydrochloride to both eyes of the dog. Use a flat tonometer to measure intraocular pressure. Calibrate the tonometer before the study. The measured intraocular pressure change was 5%. In TB, T0, T5, T10, and T15 monitor blood oxygen saturation (SpO2), pulse rate, respiration rate, and systolic blood pressure to assess cardiopulmonary function. Use SPSS software to perform statistical analysis on the data.

  Result: The average intraocular pressure and blood pressure SD of the treatment group and the control group are shown in the figure, and all data are expressed in millimeters of mercury. The baseline IOP values of the treatment and control (before induction; Tb) were 19.5±2.2 and 21.6±2.6, respectively. There was no significant difference in baseline intraocular pressure between the treatment group and the control group. Compared with the intraocular pressure of the control group before induction (21.6±2.6), the intraocular pressure after induction (27.5±3.1) and 5 minutes after tracheal intubation (25±2.4) increased significantly. The systolic blood pressure did not increase significantly after induction (137.5±4.1), and it was still higher than before induction (130.6±4.9) 5 minutes after tracheal intubation, but the difference was statistically significant. It's not. There is a significant difference between the IOP values between the treatment group and the control group T0 and T5. In the treatment group, the intraocular pressure (18.6±1.9) (17.4±1.8) after induction and 5 minutes after tracheal intubation did not change significantly compared with the value before induction (19.5±2.2). There was no significant difference in intraocular pressure between the treatment groups. Treatment group: The systolic blood pressure before introduction and 5 minutes after intubation tended to decrease. 15 minutes after tracheal intubation, the systolic blood pressure of both groups decreased significantly. Discussion: This study evaluated the effect of oral gabapentin on changes in intraocular pressure in dogs after tracheal intubation. The clinically available dose (10-60mg/kg) will reach the highest plasma concentration 1 to 3 hours later. This information helps explain our results. Oral gabapentin can significantly prevent the increase in intraocular pressure caused by tracheal intubation. These findings are similar to previous human studies and indicate that gabapentin is a useful adjuvant to prevent the increase in intraocular pressure during tracheal intubation. The baseline IOP values of dogs observed in this study before treatment were similar to those of normal dogs. The exact mechanism of gabapentin in reducing intraocular pressure in dogs is still unclear. Several mechanisms have been proposed to explain the regulation of intraocular pressure by gabapentin. The blood volume in the eye depends on the arterial inflow, venous outflow, and vascular tone in the eye. These changes in the blood volume of the eye will change the IOP. By improving the flow of aqueous humor to inhibit membrane voltage-gated calcium channels (similar to calcium channel blockers) to inhibit gabopentin, it can have a relaxing effect on the ciliary muscle, thereby improving intraocular pressure. It also means existence. In this study, the intraocular pressure after treatment was compared with baseline and negative control groups. In this study, the control group was considered to be able to correctly assess the effects of time, anesthesia and intubation on IOP measurements. An interesting finding in this study is the important effect of gabapentin on blood pressure. The current study found that compared with the baseline value, there was a statistically significant decrease in systolic blood pressure at 5 minutes after intubation. Our results are consistent with previous human studies, which showed that gabapentin inhibits tracheal voltage-gated calcium channels, thereby increasing blood pressure after tracheal intubation. In fact, the success of eye surgery depends on the control of intraocular pressure before, during and after surgery. Anesthesia management should minimize changes during the entire anesthesia, especially elevated intraocular pressure. Certain ophthalmic diseases require that the intraocular pressure be kept below or above the reference range during general anesthesia. For example, corneal injuries that are close to full thickness require careful handling and control of intraocular pressure to avoid accidental perforations before and during surgery. Patients with corneal perforation, especially iris prolapse, have poor postoperative vision. Therefore, it is necessary to find a safe method for the treatment of elevated intraocular pressure in dogs undergoing eye surgery.

  Conclusion: According to the results of this study, preoperative oral gabapentin can significantly prevent the increase in intraocular pressure caused by canine propofol anesthesia tracheal intubation. Gabapentin seems to be a drug that inhibits the increase in intraocular pressure. Eye surgery on dogs with deep ulcers and tears can ensure treatment. Increased intraocular pressure can cause ocular complications, such as eye perforation.