[Role of spinal P2X4 receptor in remifentanil-induced postoperative hyperalgesia].

OBJECTIVE: To explore the role of P2X4 receptor in opioid-induced hyperalgesia (OIH).
 Methods: A total of 30 Sprague-Dawley (SD) male rats were randomly divided into 5 groups: a saline (N0) group, a remifentanil at 0.5 µg/(kg.min) (R1) group, a remifentanil at 1.0 µg/(kg.min) (R2) group, a remifentanil at 1.5 µg/(kg.min) (R3) group, and a remifentanil at 5.0 µg/(kg.min) (R4) group. The paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) were measured at follow time points to optimize the dosages: the day before treatment (T1), 30 min after tail intravenous catheterization (T2), and 30 min (T3), 1 h (T4), 2 h (T5), 24 h (T6) after withdrawal from remifentanil. Then, the rats were randomly divided into 2 groups: a saline group (N group), a remifentanil at 1.0 µg/(kg.min) group (R group). The PWMT and PWTL were measured at follow time points: T1, T2, and T4. The lumbar enlargement of spine was selected at 1 h after withdrawal from remifentanil, and the expression of P2X4 receptor mRNA and protein was examined in OIH. Additional male rats were selected and randomly divided into 2 groups: a plantar incision surgery followed by saline treatment group (I+N group), a plantar incision surgery followed by remifentanil treatment group (I+R group). The PWMT and PWTL were measured at follow time points: T1, T2, T3, T4, T5, T6, 48 h (T7) and 72 h (T8) after withdrawal from remifentanil. The lumbar enlargement of spine was selected at 1 h after withdrawal from remifentanil, the expression of P2X4 receptor mRNA and protein was examined by PCR and Western blotting, and the microglial activation in spine 1 h after withdrawal from remifentanil were assessed by immunofluorescence.
 Results: The pain thresholds including PWMT and PWTL in different groups were as follows: R4 group

Performance of Lung Ultrasound in Detecting Peri-Operative Atelectasis after General Anesthesia.

The aim of this prospective observational study was to evaluate the performance of lung ultrasound (LUS) in detecting post-operative atelectasis in adult patients under general anesthesia. Forty-six patients without pulmonary comorbidities who were scheduled for elective neurosurgery were enrolled in the study. A total of 552 pairs of LUS clips and thoracic computed tomography (CT) images were ultimately analyzed to determine the presence of atelectasis in 12 prescribed lung regions. The accuracy of LUS in detecting peri-operative atelectasis was evaluated with thoracic CT as gold standard. Levels of agreement between the two observers for LUS and the two observers for thoracic CT were analyzed using the κ reliability test. The quantitative correlation between LUS scores of aeration and the volumetric data of atelectasis in thoracic CT were further evaluated. LUS had reliable performance in post-operative atelectasis, with a sensitivity of 87.7%, specificity of 92.1% and diagnostic accuracy of 90.8%. The levels of agreement between the two observers for LUS and for thoracic CT were both satisfactory, with κ coefficients of 0.87 (p < 0.0001) and 0.93 (p < 0.0001), respectively. In patients in the supine position, LUS scores were highly correlated with the atelectasis volume of CT (r = 0.58, p < 0.0001). Thus, LUS provides a fast, reliable and radiation-free method to identify peri-operative atelectasis in adults.