Avance cs2

On P7, rats were randomly allocated to one of the following protocols for 3% sevoflurane exposure as was described in previous studies (16 (link),17 (link)): continuous exposure for 0, 1, 2, 4, or 6 h or cumulative exposure for 6 h in 24 h (2 h sevoflurane followed by 6 h fresh air, repeated for 3 cycles). These groups were designated T1-T6 and T6in, respectively. All animals were kept in a 30% oxygen environment in an acrylic chamber within an incubator set to 37°C to maintain rectal temperatures of 36.5-37.5°C. The inhaled anesthetic and oxygen concentrations were controlled by an anesthesia apparatus (Avance CS², General Electric, USA) and adjusted according to the instructions. Every 30 minutes, the pulse and peripheral oxygen saturation of the animals were measured by a handheld pulse oximeter (MD200K2, ChoiceMMed, USA). In each group, 6 male rats and 6 female rats were sacrificed by cervical dislocation for blood gas analysis and western blotting after the sevoflurane exposure period. The remaining rats were sacrificed in the same way for western blotting after the Morris water maze test.

General anesthesia was induced using midazolam (0.05−0.1 mg/kg), fentanyl (2−4 μg/kg), propofol (1.5−2.5 mg/kg), and rocuronium (0.6−0.9 mg/kg). After oral intubation, mechanical ventilation was maintained for the duration of the surgery, with the ventilator (Avance CS2; GE Health Care) parameters set at a tidal volume of 8−10 mL/kg and frequency of 18−22 times/min to maintain the oxygen saturation >95%. Combined anesthesia with sevoflurane (1.5−2.0 Vol%) inhalation as well as propofol (2−10 mg·kg⁻¹·h⁻¹) and remifentanil (0.01−0.2 μg·kg⁻¹·min⁻¹) intravenous maintenance were used to stabilize the anesthetic effect and maintain the bispectral index ranging from 40 to 60.

Once a satisfactory sedation level was achieved, a nasopharyngeal airway was inserted. PetCO₂ monitoring was performed using an infrared CO₂ analyzer (Avance CS², GE Healthcare, Madison, WI, USA) by inserting a sample line into the nasopharyngeal airway to minimize the potential under-detection of exhaled gas due to airway obstruction (Figure 1). The radial artery on the non-operated side was cannulated to monitor continuous arterial blood pressure and sample arterial blood for gas analysis. PtcCO₂ was measured using a TCM4^TM device (Radiometer, Copenhagen, Denmark). The transcutaneous monitoring technique was standardized by applying a probe on the forearm ipsilateral to the non-operated lung in the lateral decubitus position (Figure 1). Before placement, the device was calibrated ex vivo as per the manufacturer’s recommendations. Then, the skin surface where the electrode was placed was swabbed with alcohol to facilitate disc adhesion. Subsequently, the probe was mounted on the electrode with the working temperature set to 42 °C to arterialize the capillary blood flow in the skin. The subsequent in vivo calibration was based on the results of the first ABGA performed after a 10-min equilibration period from the time of the placement of probe on the patient for stabilization of the measurement [14 (link),15 (link)].