Anesthesia and the renal sympathetic nervous system in perioperative AKI

Urinary oxygen tension and its role in predicting acute kidney injury: A narrative review

Acute kidney injury occurs frequently in the perioperative setting. The renal medulla often endures hypoxia or hypoperfusion and is susceptible to the imbalance between oxygen supply and demand due to the nature of renal blood flow distribution and metabolic rate in the kidney. The current available evidence demonstrated that the urine oxygen pressure is proportional to the variations of renal medullary tissue oxygen pressure. Thus, urine oxygenation can be a candidate for reflecting the change of oxygen in the renal medulla. In this review, we discuss the basic physiology of acute kidney injury, as well as techniques for monitoring urine oxygen tension, confounding factors affecting the reliable measurement of urine oxygen tension, and its clinical use, highlighting its potential role in early detection and prevention of acute kidney injury.

The Effects of Volatile Anesthetics on Renal Sympathetic and Phrenic Nerve Activity during Acute Intermittent Hypoxia in Rats

Coordinated activation of sympathetic and respiratory nervous systems is crucial in responses to noxious stimuli such as intermittent hypoxia. Acute intermittent hypoxia (AIH) is a valuable model for studying obstructive sleep apnea (OSA) pathophysiology, and stimulation of breathing during AIH is known to elicit long-term changes in respiratory and sympathetic functions. The aim of this study was to record the renal sympathetic nerve activity (RSNA) and phrenic nerve activity (PNA) during the AIH protocol in rats exposed to monoanesthesia with sevoflurane or isoflurane. Adult male Sprague-Dawley rats (n = 24; weight: 280-360 g) were selected and randomly divided into three groups: two experimental groups (sevoflurane group, n = 6; isoflurane group, n = 6) and a control group (urethane group, n = 12). The AIH protocol was identical in all studied groups and consisted in delivering five 3 min-long hypoxic episodes (fraction of inspired oxygen, FiO2 = 0.09), separated by 3 min recovery intervals at FiO2 = 0.5. Volatile anesthetics, isoflurane and sevoflurane, blunted the RSNA response to AIH in comparison to urethane anesthesia. Additionally, the PNA response to acute intermittent hypoxia was preserved, indicating that the respiratory system might be more robust than the sympathetic system response during exposure to acute intermittent hypoxia.

Effects of Subcostal Anterior Quadratus Lumborum Block with and without Dexmedetomidine on Postoperative Rehabilitation in Patients Undergoing Laparoscopic Renal Surgery: A Prospective Double-Blinded Randomized Controlled Study

Background

The combination of different anesthesia techniques or adjuvant drugs can relieve the stress response to surgery, reduce adverse reactions and improve the clinical outcome. We investigated the effects of subcostal anterior quadratus lumborum block (SQLB) with and without dexmedetomidine (DEX) on postoperative rehabilitation for laparoscopic renal surgery (LRS).

Methods

We included 90 patients in this single-center study. All were scheduled for elective laparoscopic radical or partial nephrectomy under general anesthesia (GA). We randomly and evenly assigned them to three groups: Group GA (GA alone), Group QG (SQLB with 30 mL of 0.25% ropivacaine and GA), and Group DQG (SQLB with 30 mL of 0.25% ropivacaine plus 1 μg/kg DEX and GA). The primary outcomes were serum creatinine (Cr) and blood urea nitrogen (BUN) levels; the secondary outcomes included the average numeric rating scale (NRS) scores at rest and during activity within 48 h postoperatively; perioperative opioid consumption; the time to first ambulation, exhaust, and fluid intake, and postoperative adverse reactions.

Results

The serum Cr and BUN levels in Group DQG decreased significantly compared with Group GA (P < 0.05). The average NRS scores in Group DQG were significantly lower than other two groups (P < 0.05). Furthermore, the indexes reduced significantly in Group QG compared with Group GA (P < 0.05). Groups DQG and QG had lower consumption of opioid compared with Group GA (P < 0.05). The recovery indicators in Groups DQG and QG were higher quality than Group GA (P < 0.05). The incidences of adverse reactions in Group DQG was significantly lower than the other groups (P < 0.05).

Conclusion

SQLB with and without DEX could attenuate postoperative pain, reduce opioids requirement and side effects, as well as facilitate postoperative early rehabilitation. More interesting, SQLB with DEX could confer kidney protection.

Clinical Trial Registration Number

The Chinese Clinical Trial Registry (ChiCTR2200061554).

Postoperative acute kidney injury after volatile or intravenous anesthesia: a meta-analysis

Postoperative acute kidney injury (AKI) is a common complication after surgery. The pathophysiology of postoperative AKI is complex. One potentially important factor is anesthetic modality. We, therefore, conducted a meta-analysis of the available literature regarding anesthetic modality and incidence of postoperative AKI. Records were retrieved until January 17, 2023, with the search terms ("propofol" OR "intravenous") AND ("sevoflurane" OR "desflurane" OR "isoflurane" OR "volatile" OR "inhalational") AND ("acute kidney injury" OR "AKI"). A meta-analysis for common effects and random effects was performed after exclusion assessment. Eight records were included in the meta-analysis with a total of 15,140 patients (n = 7,542 propofol and n = 7,598 volatile). The common and random effects model revealed that propofol was associated with a lower incidence of postoperative AKI compared with volatile anesthesia [odds ratio: 0.63 (95% confidence interval: 0.56-0.72) and 0.49 (95% confidence interval: 0.33-0.73), respectively]. In conclusion, the meta-analysis revealed that propofol anesthesia is associated with a lower incidence of postoperative AKI compared with volatile anesthesia. This may motivate choosing propofol-based anesthesia in patients with increased risk of postoperative AKI due to preexisting renal impairment or surgery with a high risk of renal ischemia.NEW & NOTEWORTHY This study analyzed the available literature on anesthetic modality and incidence of postoperative AKI. The meta-analysis revealed that propofol is associated with lower incidence of AKI compared with volatile anesthesia. It might therefore be considerable to use propofol anesthesia in surgeries with increased susceptibility for developing renal injuries such as cardiopulmonary bypass and major abdominal surgery.