Evaluation of the anesthetic depth and bispectral index during propofol sequential target-controlled infusion in dogs

Abstract

Background and Aim: The use of anesthetic infusions based on pharmacokinetic values associated with anesthetic plan and bispectral index in dogs have not been well-documented in the literature. This study aimed to evaluate the bispectral index (BIS) change based on pre-propofol and establish clinical anesthetic depth changes during propofol sequential target-controlled infusion (STCI) in dogs with a plasma target of 5 μg/mL. Materials and Methods: Twenty healthy male dogs aged 1-3 years and weighing 9.8-44 kg were recruited. These dogs were pre-medicated intramuscularly with methadone (0.2 mg/kg) and acepromazine (0.03 mg/kg). After 30 min, propofol anesthetic induction and maintenance were initiated using STCI according to dog pharmacokinetic (PK) parameters. Subsequently, the target plasma concentration of propofol was set at 5 μg/mL for both anesthetic induction and the 120 min maintenance. Then, TivaTrainer v.9.1 software was used to calculate anesthetic infusion rates in a TCI plasmatic concentration mode using the PKs model optimized by covariates for propofol TCI in dogs. The BIS value was recorded every 5 min from the beginning of induction until the end of anesthesia. Finally, analysis of variance was performed on numerical data using the Friedman test, followed by the Bonferroni adjustment (p<0.05). Results: A statistical difference was observed between the baseline BIS value (T0), with a median value of 84.5 (81-97), and BIS after every 15 min (T15) of inducing anesthesia. Surgical anesthetic depth was also reached in 18 of 20 dogs after 10 min of infusion and in all dogs after 20 min, with a median BIS value of 72 (53-89) at the time of surgical anesthesia depth. Results also showed no BIS variation (p<0.05) between anesthetic moments after anesthetic induction with a substantial amplitude of BIS in the surgical anesthetic depth. Moreover, the maximum depth of anesthesia in all dogs by clinical evaluation was reached after 20 min of anesthesia and then remained stable throughout the anesthetic period. Conclusion: This study suggested that most dogs (90%) attained a surgical depth of anesthesia within 15 min of STCI onset, with a plasma target of 5 μg/mL and no change in anesthetic depth throughout the period anesthesia lasted. Furthermore, median BIS values remained high even after dogs reached the surgical depth of anesthesia, indicating that the comparison of BIS values of dogs and humans should not be considered for classifying anesthetic and hypnotic depths in dogs.

Thoracic transversus plane block as part of a multimodal analgesia plan in a cat undergoing sternotomy

“…After aseptical preparation of the right cervical region, a small incision was performed in the skin over the region of the jugular vein and a 4.5 Fr, 6‐cm long jugular catheter (Multicath Forward, Vygon, Germany) was placed by the Seldinger technique. The depth of anaesthesia was monitored with the use of clinical parameters such as the jaw tone, eye position and palpebral reflex and the HR, RR and blood pressure 19 …”

“…The depth of anaesthesia was monitored with the use of clinical parameters such as the jaw tone, eye position and palpebral reflex and the HR, RR and blood pressure. 19 After the patient was surgically prepared for surgery, the US-guided TTP block (Figure 2) was performed using a 1.5-inch, 22-gauge spinal needle (BD Spinal Needle; BD Medical, Franklin Lakes, NJ, USA). The needle was inserted in a ventrolateral-to-dorsomedial direction with an in-plane technique at the level of fourth intercostal space using a 15-6 MHz linear transducer (SonoSite, Washington, USA) (Figure 3), and it was advanced through the pectoralis profunda, rectus abdominis, external and internal intercostal muscles, and internal intercostal membrane until the tip was positioned into the TTP, ventral to transversus thoracic muscle (Figure 4).…”