Effect of intraoperative low vs. conventional tidal volume on the incidence of postoperative acute kidney injury after noncardiac surgery: a two-center randomized clinical trial.

BACKGROUND: In adults undergoing noncardiac surgery, the correlation between intraoperative tidal volume and postoperative acute kidney injury (AKI) is unclear. This study aimed to investigate the effects of low tidal volume ventilation on the incidence of postoperative AKI compared with conventional tidal volume in adults undergoing noncardiac surgery. METHODS: This was a two-center prospective randomized controlled trial on adult patients who underwent noncardiac surgery and had a mechanical ventilation of >60 min. Patients were randomized to receive either a tidal volume of 6 mL/kg pre-predicted body weight (PBW, low tidal volume) or a tidal volume of 10 mL/kg pre-predicted body weight (conventional tidal volume). The primary outcome was the incidence of AKI after non-cardiac surgery. Appropriate statistical methods were used for this study. RESULTS: Among the 1982 randomized patients, 943 with low tidal volume and 958 with conventional tidal volume were evaluable for the primary outcome. Postoperative AKI occurred in 12 patients (1.3%) in the low tidal volume group and 11 patients (1.1%) in the conventional tidal volume group, with an odds ratio of 0.889 (95%CI, 0.391-2.03) and a relative risk of 0.999 ([95%CI, 0.989-1.01]; P=0.804). Postoperative serum creatinine levels increased in 284 (30.0%) patients with low tidal volume compared to 316 (32.0%) patients with conventional tidal volume (P=0.251). No difference in postoperative serum creatinine levels was found between the two groups (57.5 [49.0-68.2] µmol/L vs. 58.8[50.4-69.5] µmol/L, P=0.056). CONCLUSIONS: Among adults undergoing noncardiac surgery, low tidal volume mechanical ventilation did not significantly reduce the incidence of postoperative AKI compared with conventional tidal volume.

Ketamine administration ameliorates anesthesia and surgery-induced cognitive dysfunction via activation of TRPV4 channel opening.

Perioperative neurocognitive disorder (PND) is a common complication associated with anesthesia and surgery in the elderly. The dysfunction of transient receptor potential vanilloid 4 (TRPV4) has been associated with a number of diseases, including Alzheimer's disease. Given that ketamine can reportedly improve PNDs, the present study sought to determine whether ketamine-induced PND alleviation was mediated by activation of TRPV4 channel opening. A total of 120, 20-month-old male C57BL/6 mice were randomly divided into five groups: Vehicle, PND (tibial fracture surgery), PND + ketamine (Ket), PND + Ket + HC-067047 (HC), and PND + HC groups. Ketamine (0.5 mg/kg) was administered intraperitoneally once a day for 3 days after surgery and HC-067047 (1 µmol/2 µl), an antagonist of TRPV4, was administered via the left lateral ventricle 30 min before ketamine treatment. Superoxide dismutase (SOD), malondialdehyde (MDA), lipid peroxidation (LPO), IL-1ß, IL-6, adenosine monophosphate-activated protein kinase (AMPK), NF-κB, TNF-α and IFN-ß levels were determined 3 days after surgery. At 28 days after surgery, fear conditioning and novel object recognition were assessed, and Aß1-42 levels were measured and ionized calcium binding adaptor molecule 1 (Iba1) staining was conducted on day 31 after surgery. The results revealed that ketamine administration upregulated total SOD activity, downregulated MDA and LPO content, mitigated phosphorylated (p)-NF-κB, TNF-α mRNA and IFN-ß mRNA expression in the hippocampus, and promoted p-AMPK 3 days after surgery. Furthermore, it was found that ketamine increased both context- and tone-dependent fear conditioning, and the time spent exploring a novel object, and reduced Aß peptide levels and microglial activation 30 days after surgery. Notably, these changes could be reversed by HC-067047 to a certain extent. In conclusion, ketamine improved PND in aged mice after tibial fracture surgery and the potential mechanism may involve activation of the TRPV4/AMPK/NF-κB signaling pathway.

Grip strength can be used to evaluate postoperative residual neuromuscular block recovery in patients undergoing general anesthesia.

BACKGROUND: Residual postoperative neuromuscular blockade is an important clinical issue. Neuromuscular monitoring is usually used to evaluate neuromuscular recovery in patients undergoing general anesthesia. However, this procedure is inconvenient and not widely adopted. We aimed to examine the correlation between grip strength and train-of-four ratio (TOFr) to examine whether assessing grip strength can be used clinically to monitor residual neuromuscular blockade. METHODS: One hundred twenty patients with ASA I or II scheduled for laparoscopic cholecystectomy under general anesthesia were enrolled in this study. All patients were randomly selected to receive standard anesthesia induction with either 0.6 mg·kg rocuronium or 0.2 mg·kg cisatracurium. Grip strength was tested in all patients using an electronic device before anesthesia and when TOFr values of 0.7, 0.8, and 0.9, and an hour later of TOFr value of 0.25. The time required for a change in TOFr values from 0.25 to 0.75 and 0.9 was evaluated. Spearman rank correlation analysis was performed to determine correlations between grip strength and TOFr. RESULTS: Spearman rank correlation analysis indicated that there was a significant correlation between grip strength and TOFr during patient recovery from general anesthesia (correlation coefficient for grip strength recovery [rs] = 0.886). Subgroup analysis revealed that there were no differences in mean maximum grip value recovery between patients treated with rocuronium and those treated with cisatracurium when TOFr was 0.7, 0.8, and 0.9 or when the TOFr was 0.25 after 60 minutes (all P >.05). Recovery of TOFr from 0.25 to 0.75 and from 0.25 to 0.9 was longer in patients treated with rocuronium than in those treated with cisatracurium (both P <.001). CONCLUSION: There was a strong correlation between grip strength and TOFr during recovery from general anesthesia. Evaluation of grip strength can be used as an additional strategy to evaluate postoperative residual neuromuscular blockade.