Therapeutic value of a lung protective ventilation strategy in acute lung injury

Lung protective ventilation strategy to reduce postoperative pulmonary complications (PPCs) in patients undergoing robot-assisted laparoscopic radical cystectomy for bladder cancer: A randomized double blinded clinical trial

STUDY OBJECTIVE

To evaluate the effects of ventilation with low tidal volume and positive end-expiratory pressure (PEEP) on postoperative pulmonary complications in patients undergoing robot-assisted laparoscopic radical cystectomy (RARC) for bladder cancer.

DESIGN

A prospective randomized double-blinded study.

SETTING

A single center trial in a comprehensive tertiary hospital from January 2017 to January 2019.

PATIENTS

A total of 258 patients undergoing RARC for bladder cancer.

INTERVENTIONS

Patients were randomly assigned to receive either lung-protective ventilation (LPV group) [tidal volume 6 ml/ kg predicated body weight (PBW) + PEEP 7 cmH₂O] or nonprotective ventilation (control group) (tidal volume 9 ml/ kg PBW without PEEP) during anesthesia.

MEASUREMENTS

The primary outcome was the occurrence of postoperative pulmonary complications (PPCs) during the first 90 days after surgery. The secondary outcomes were extubation time, oxygenation index (OI) after extubation and at postoperative day 1 in blood gas.

MAIN RESULTS

The incidence of PPCs at postoperative day1, 2 and 3 were lower in LPV group [26.8% vs. 47.2%, odds ratio (OR) 0.41, 95% confidence interval (CI), 0.24-0.69, P = 0.0007, 21.3% vs. 43.3%, OR 0.36, 95% CI, 0.20-0.61, P = 0.0002, 14.2% vs. 27.5%, OR0.43, 95%CI, 0.23-0.82, P = 0.0087, respectively], while no differences were observed at day 7 and 28 (3.9% vs. 9.4%, P = 0.0788, 0% vs. 1.6%, P = 0.4980, respectively). No PPCs were observed at postoperative day 90 in both groups. Furthermore, immediately after extubating and at postoperative day 1, OI was significantly higher in LPV group compared with control group [390(337-467) vs. 343(303-420), P = 0.0005, 406.7(73.0) vs. 425.5(74.7), P = 0.0440, respectively]. Patients in LPV group had a significant shorter extubation time after operation compared with control group [38(33-54) vs. 35(25-46), P = 0.0012].

CONCLUSION

LPV combining low tidal volume and PEEP during anesthesia for RARC may decrease the incidence of postoperative pulmonary complications.

Activation of Liver X Receptor Attenuates Oleic Acid-Induced Acute Respiratory Distress Syndrome

Liver X receptors (LXRs) were identified as receptors that sense oxidized cholesterol derivatives. LXRs are best known for their hepatic functions in regulating cholesterol metabolism and triglyceride synthesis, but whether and how LXRs play a role in the lung diseases is less understood. To study the function of LXRs in acute respiratory distress syndrome (ARDS), we applied the oleic acid (OA) model of ARDS to mice whose LXR was genetically or pharmacologically activated. The VP-LXRα knock-in (LXR-KI) mice, in which a constitutively activated LXRα (VP-LXRα) was inserted into the mouse LXRα locus, were used as the genetic gain-of-function model. We showed that the OA-induced lung damages, including the cytokine levels and total cell numbers and neutrophil numbers in the bronchoalveolar lavage fluid, the wet/dry weight ratio, and morphological abnormalities were reduced in the LXR-KI mice and wild-type mice treated with the LXR agonist GW3965. The pulmonoprotective effect of GW3965 was abolished in the LXR-null mice. Consistent with the pulmonoprotective effect of LXR and the induction of antioxidant enzymes by LXR, the OA-induced suppression of superoxide dismutase and catalase was attenuated in LXR-KI mice and GW3965-treated wild-type mice. Taken together, our results demonstrate that activation of LXRs can alleviate OA-induced ARDS by attenuating the inflammatory response and enhancing antioxidant capacity.

Renal dopaminergic system: Pathophysiological implications and clinical perspectives

Fluid homeostasis, blood pressure and redox balance in the kidney are regulated by an intricate interaction between local and systemic anti-natriuretic and natriuretic systems. Intrarenal dopamine plays a central role on this interactive network. By activating specific receptors, dopamine promotes sodium excretion and stimulates anti-oxidant and anti-inflammatory pathways. Different pathological scenarios where renal sodium excretion is dysregulated, as in nephrotic syndrome, hypertension and renal inflammation, can be associated with impaired action of renal dopamine including alteration in biosynthesis, dopamine receptor expression and signal transduction. Given its properties on the regulation of renal blood flow and sodium excretion, exogenous dopamine has been postulated as a potential therapeutic strategy to prevent renal failure in critically ill patients. The aim of this review is to update and discuss on the most recent findings about renal dopaminergic system and its role in several diseases involving the kidneys and the potential use of dopamine as a nephroprotective agent.

Dopamine inhibits pulmonary edema through the VEGF-VEGFR2 axis in a murine model of acute lung injury

The neurotransmitter dopamine and its dopamine receptor D2 (D2DR) agonists are known to inhibit vascular permeability factor/vascular endothelial growth factor (VEGF)-mediated angiogenesis and vascular permeability. Lung injury is a clinical syndrome associated with increased microvascular permeability. However, the effects of dopamine on pulmonary edema, a phenomenon critical to the pathophysiology of both acute and chronic lung injuries, have yet to be established. Therefore, we sought to determine the potential therapeutic effects of dopamine in a murine model of lipopolysaccharide (LPS)-induced acute lung injury (ALI). Compared with sham-treated controls, pretreatment with dopamine (50 mg/kg body wt) ameliorated LPS-mediated edema formation and lowered myeloperoxidase activity, a measure of neutrophil infiltration. Moreover, dopamine significantly increased survival rates of LPS-treated mice, from 0-75%. Mechanistically, we found that dopamine acts through the VEGF-VEGFR2 axis to reduce pulmonary edema, as dopamine pretreatment in LPS-treated mice resulted in decreased serum VEGF, VEGFR2 phosphorylation, and endothelial nitric oxide synthase phosphorylation. We used D2DR knockout mice to confirm that dopamine acts through D2DR to block vascular permeability in our lung injury model. As expected, a D2DR agonist failed to reduce pulmonary edema in D2DR(-/-) mice. Taken together, our results suggest that dopamine acts through D2DR to inhibit pulmonary edema-associated vascular permeability, which is mediated through VEGF-VEGFR2 signaling and conveys protective effects in an ALI model.