Intravenous Infusion of Dexmedetomidine Combined Isoflurane Inhalation Reduces Oxidative Stress and Potentiates Hypoxia Pulmonary Vasoconstriction during One-Lung Ventilation in Patients

Dexmedetomidine as a Short-Use Analgesia for the Immature Nervous System

Pain management in neonates continues to be a challenge. Diverse therapies are available that cause loss of pain sensitivity. However, because of side effects, the search for better options remains open. Dexmedetomidine is a promising drug; it has shown high efficacy with a good safety profile in sedation and analgesia in the immature nervous system. Though dexmedetomidine is already in use for pain control in neonates (including premature neonates) and infants as an adjunct to other anesthetics, the question remains whether it affects the neuronal activity patterning that is critical for development of the immature nervous system. In this study, using the neonatal rat as a model, the pharmacodynamic effects of dexmedetomidine on the nervous and cardiorespiratory systems were studied. Our results showed that dexmedetomidine has pronounced analgesic effects in the neonatal rat pups, and also weakly modified both the immature network patterns of cortical and hippocampal activity and the physiology of sleep cycles. Though the respiration and heart rates were slightly reduced after dexmedetomidine administration, it might be considered as the preferential independent short-term therapy for pain management in the immature and developing brain.

Dexmedetomidine improves pulmonary outcomes in thoracic surgery under one-lung ventilation: A meta-analysis

INTRODUCTION

Dexmedetomidine improves intrapulmonary shunt in thoracic surgery and minimizes inflammatory response during one-lung ventilation (OLV). However, it is unclear whether such benefits translate into less postoperative pulmonary complications (PPCs). Our objective was to determine the impact of dexmedetomidine on the incidence of PPCs after thoracic surgery.

METHODS

Major databases were used to identify randomized trials that compared dexmedetomidine versus placebo during thoracic surgery in terms of PPCs. Our primary outcome was atelectasis within 7 days after surgery. Other specific PPCs included hypoxemia, pneumonia, and acute respiratory distress syndrome (ARDS). Secondary outcome included intraoperative respiratory mechanics (respiratory compliance [Cdyn]) and postoperative lung function (forced expiratory volume [FEV1]). Random effects models were used to estimate odds ratios (OR).

RESULTS

Twelve randomized trials, including 365 patients in the dexmedetomidine group and 359 in the placebo group, were analyzed in this meta-analysis. Patients in the dexmedetomidine group were less likely to develop postoperative atelectasis (2.3% vs 6.8%, OR 0.42, 95%CI 0.18-0.95, P = 0.04; low certainty) and hypoxemia (3.4% vs 11.7%, OR 0.26, 95%CI 0.10-0.68, P = 0.01; moderate certainty) compared to the placebo group. The incidence of postoperative pneumonia (3.2% vs 5.8%, OR 0.57, 95%CI 0.25-1.26, P = 0.17; moderate certainty) or ARDS (0.9% vs 3.5%, OR 0.39, 95%CI 0.07-2.08, P = 0.27; moderate certainty) was comparable between groups. Both intraoperative Cdyn and postoperative FEV1 were higher among patients that received dexmedetomidine with a mean difference of 4.42 mL/cmH2O (95%CI 3.13-5.72) and 0.27 L (95%CI 0.12-0.41), respectively.

CONCLUSION

Dexmedetomidine administration during thoracic surgery may potentially reduce the risk of postoperative atelectasis and hypoxemia. However, current evidence is insufficient to demonstrate an effect on pneumonia or ARDS.

[Effects of Rhodiola rosea injection on intrapulmonary shunt and blood IL-6 and TNF-α levels during single lung ventilation in patients undergoing radical resection of esophageal cancer]

OBJECTIVE

To explore the effects of Rhodiola rosea injection on pulmonary shunt and serum interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) levels during single lung ventilation in patients undergoing radical resection of esophageal cancer.

METHODS

Forty-six patients undergoing radical operation for esophageal cancer were randomized equally into control group and Rhodiola rosea injection group. In the Rhodiola group, 10 mL of Rhodiola rosea injection was added into 250 mL of normal saline or 5% glucose solution for slow intravenous infusion, and normal saline of the same volume was used in the control group after the patients entered the operation room. At T0, T1 and T3, PaO2 of the patient was recorded and 2 mL of deep venous blood was collected for determination of serum TNF-α and IL-6 levels. The incidence of postoperative atelectasis of the patients was recorded.

RESULTS

Compared with those in the control group, the patients receiving Rhodiola rosea injection had significantly higher PaO2 and Qs/Qt at T1 and T2 (P<0.05) and lower serum IL-6 and TNF-α levels at T3 (P<0.05). No significant difference in the incidence of postoperative atelectasis was observed between the two groups (P>0.05).

CONCLUSION

Rhodiola rosea injection before anesthesia induction can reduce intrapulmonary shunt during single lung ventilation, improve oxygenation, reduce serum IL-6 and TNF-α levels, and alleviate intraoperative lung injury in patients undergoing radical resection of esophageal cancer.

Effect of Dexmedetomidine on Oxygen and Intrapulmonary Shunt (Qs/Qt) During One-Lung Ventilation in Pediatric Surgery: A Randomized Controlled Trial

Background One-lung ventilation (OLV) is a common ventilation technique used during thoracic surgery. It can cause serious complications in children, and hypoxic pulmonary vasoconstriction (HPV) is a protective mechanism against the resulting hypoxia. Dexmedetomidine does not affect HPV, so we will investigate its impact on the partial pressure of oxygen in arterial blood (PaO2) and pulmonary shunt fraction (Qs/Qt). Methods Children who underwent OLV were divided into two equal groups. The Dex group received 0.4 μg/kg/h of dexmedetomidine intravenously. The placebo group received normal saline. Two blood samples were taken to analyze arterial and central venous blood gasses during four time periods: T1, 10 minutes after anesthesia; T2, 10 minutes after OLV; T3, 60 minutes after OLV; and T4, 20 minutes after the end of OLV. Heart rate, mean arterial pressure (MAP), PaO2, Qs/Qt, and peak inspiratory pressure (PIP) values were recorded at these time points. Results Regarding heart rate, the Dex group remained relatively stable, whereas the placebo group showed a slight increase in T3 and T4. Concerning MAP, the Dex group had a reduction at T1 compared with the placebo group and remained similar for other points. PaO2 decreased with OLV. However, the Dex group consistently maintained higher PaO2 values than the placebo, especially in T3 and T4. Concerning Qs/Qt, the Dex group maintained lower time values than the placebo group at OLV. Regarding PIP, the Dex group had significantly lower T2 and T3 than the placebo group. Conclusion Administration of dexmedetomidine in children with OLV improves PaO2 and reduces pulmonary shunt fraction (Qs/Qt), thereby improving oxygen transport. It reduces the maximum PIP values, thereby reducing pressure-related complications.

Transcutaneous electrical acupoint stimulation improves pulmonary function by regulating oxidative stress during one-lung ventilation in patients with lung cancer undergoing thoracoscopic surgery: a randomized controlled trial

BACKGROUND

Our aim was to evaluate the efficacy of transcutaneous electrical acupoint stimulation (TEAS) on oxidative stress induced by one-lung ventilation, lung function, and postoperative quality of recovery in patients with lung cancer.

METHODS

The participants (n = 80) were assigned to the sham group and TEAS group. TEAS on bilateral Feishu (BL13), Zusanli (ST36), and Hegu (L14) was performed 30 minutes before induction of anesthesia and continued until the end of the surgery. In the sham group, the same acupoints were selected without electrical stimulation. PaO2/FiO2, intrapulmonary shunt ratio (Qs/Qt), alveolar-arterial oxygen tension (A-aDO2), and respiratory index (RI) were calculated to evaluate lung function before one-lung ventilation (T0), 30 min after one-lung ventilation (T1), 1 h after one-lung ventilation (T2), and 10 min after resuming two-lung ventilation (T3). The levels of malondialdehyde (MDA) and superoxide dismutase (SOD) were detected to estimate oxidative stress at T0, T1, T2, and T3. Secondary outcomes included removal time of thoracic drainage tube, duration of intensive care unit (ICU) stay, length of postoperative hospitalization, the incidence of postoperative pulmonary complications, and the Quality of Recovery-15 (QoR-15) score on postoperative day 1 and 2.

RESULTS

TEAS significantly increased PaO2/FiO2 at T1 and T2, while Qs/Qt, A-aDO2, and RI decreased remarkably from T1 to T3 (P < 0.05). Meanwhile, TEAS obviously decreased MDA and increased SOD activity at T2 and T3 (P < 0.05). Furthermore, TEAS also markedly shortened the length of ICU stay and hospital stay after surgery, whereas the QoR-15 score on postoperative day 1 and 2 was significantly higher (P < 0.05).

CONCLUSIONS

TEAS could reduce oxidative lung injury during one-lung ventilation, thereby protecting pulmonary function and effectively accelerating the early recovery of patients with lung cancer.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR2000038243).

Effects of dexmedetomidine on pulmonary function in patients receiving one-lung ventilation: a meta-analysis of randomized controlled trial

BACKGROUND

Mechanical ventilation, particularly one-lung ventilation (OLV), can cause pulmonary dysfunction. This meta-analysis assessed the effects of dexmedetomidine on the pulmonary function of patients receiving OLV.

METHODS

The Embase, PubMed, MEDLINE, Cochrane Library, ClinicalTrials.gov, and Chinese Clinical Trial Registry databases were systematically searched. The primary outcome was oxygenation index (OI). Other outcomes including the incidence of postoperative complications were assessed.

RESULTS

Fourteen randomized controlled trials involving 845 patients were included in this meta-analysis. Dexmedetomidine improved the OI at 30 (mean difference [MD]: 40.49, 95% CI [10.21, 70.78]), 60 (MD: 60.86, 95% CI [35.81, 85.92]), and 90 min (MD: 55, 95% CI [34.89, 75.11]) after OLV and after surgery (MD: 28.98, 95% CI [17.94, 40.0]) and improved lung compliance 90 min after OLV (MD: 3.62, 95% CI [1.7, 5.53]). Additionally, dexmedetomidine reduced the incidence of postoperative pulmonary complications (odds ratio: 0.44, 95% CI [0.24, 0.82]) and length of hospital stay (MD: -0.99, 95% CI [-1.25, -0.73]); decreased tumor necrosis factor-α, interleukin (IL)-6, IL-8, and malondialdehyde levels; and increased superoxide dismutase levels. However, only the results for the OI and IL-6 levels were confirmed by the sensitivity and trial sequential analyses.

CONCLUSIONS

Dexmedetomidine improves oxygenation in patients receiving OLV and may additionally decrease the incidence of postoperative pulmonary complications and shorten the length of hospital stay, which may be related to associated improvements in lung compliance, anti-inflammatory effects, and regulation of oxidative stress reactions. However, robust evidence is required to confirm these conclusions.

Effects of penehyclidine hydrochloride combined with dexmedetomidine on pulmonary function in patients undergoing heart valve surgery: a double-blind, randomized trial

AIM

To investigate the effects of penehyclidine hydrochloride combined with dexmedetomidine on pulmonary function in patients undergoing heart valve surgery with cardiopulmonary bypass (CPB).

METHODS

A total of 180 patients undergoing elective heart valve surgery with CPB were randomly divided into four groups: 45 in group P (intravenous penehyclidine hydrochloride 0.02 mg/kg 10 min before anesthesia induction and at the beginning of CPB, total 0.04 mg/kg); 43 in group D (dexmedetomidine 0.5 μg/kg/h after induction of anesthesia until the end of anesthesia); 44 in group PD ( penehyclidine hydrochloride 0.04 mg/kg combined with dexmedetomidine 0.5 μg/kg/h intravenously during anesthesia); and 43 in group C (same amount of normal saline 10 min before and after anesthesia induction, to the end of anesthesia, and at the beginning of CPB). The main outcomes were the incidence and severity of postoperative pulmonary complications (PPCs). The secondary outcomes were: (1) extubation time, length of stay in intensive care, and postoperative hospital stay, and adverse events; and (2) pulmonary function evaluation indices (oxygenation index and respiratory index) and plasma inflammatory factor concentrations (tumor necrosis factor-α, interleukin-6, C-reactive protein and procalcitonin) during the perioperative period.

RESULTS

The incidence of PPCs in groups P, D and PD after CPB was lower than that in group C (P < 0.05), and the incidence in group PD was significantly lower than that in groups P and D (P < 0.05). The scores for PPCs in groups P, D and PD were lower than those in group C (P < 0.05).

CONCLUSION

Combined use of penehyclidine hydrochloride and dexmedetomidine during anesthesia reduced the occurrence of postoperative pulmonary dysfunction, and improved the prognosis of patients undergoing heart valve surgery with CPB.

TRIAL REGISTRATION

The trial was registered in the Chinese Clinical Trial Registry on 3/11/2020 (Registration No.: ChiCTR2000039610).

Impact of pharmacological interventions on intrapulmonary shunt during one-lung ventilation in adult thoracic surgery: a systematic review and component network meta-analysis

BACKGROUND

Intrapulmonary shunt is a major determinant of oxygenation in thoracic surgery under one-lung ventilation. We reviewed the effects of available treatments on shunt, Pao₂/FiO₂ and haemodynamics through systematic review and network meta-analysis.

METHODS

Online databases were searched for RCTs comparing pharmacological interventions and intrapulmonary shunt in thoracic surgery under one-lung ventilation up to March 30, 2022. Random-effects (component) network meta-analysis compared 24 treatments and 19 treatment components. The Confidence in Network Meta-Analysis (CINeMA) framework assessed evidence certainty. The primary outcome was intrapulmonary shunt fraction during one-lung ventilation.

RESULTS

A total of 55 RCTs were eligible for systematic review (2788 participants). The addition of N₂O (mean difference [MD]=-15%; 95% confidence interval [CI], -25 to -5; P=0.003) or almitrine (MD=-13%; 95% CI, -20 to -6; P<0.001) to propofol anaesthesia were efficient at decreasing shunt. Combined epidural anaesthesia (MD=3%; 95% CI, 1-5; P=0.005), sevoflurane (MD=5%; 95% CI, 2-8; P<0.001), isoflurane (MD=6%; 95% CI, 4-9; P<0.001), and desflurane (MD=9%; 95% CI, 4-14; P=0.001) increased shunt vs propofol. Almitrine (MD=147 mm Hg; 95% CI, 58-236; P=0.001), dopexamine (MD=88 mm Hg; 95% CI, 4-171; P=0.039), and iloprost (MD=81 mm Hg; 95% CI, 4-158; P=0.038) improved Pao₂/FiO₂. Certainty of evidence ranged from very low to moderate.

CONCLUSIONS

Adding N₂O or almitrine to propofol anaesthesia reduced intrapulmonary shunt during one-lung ventilation. Halogenated anaesthetics increased shunt in comparison with propofol. The effects of N₂O, iloprost, and dexmedetomidine should be investigated in future research. N₂O results constitute a research hypothesis currently not backed by any direct evidence. The clinical availability of almitrine is limited.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO CRD42022310313.

Protective Effects of Dexmedetomidine Infusion on Genotoxic Potential of Isoflurane in Patients Undergoing Emergency Surgery

BACKGROUND

Isoflurane (ISO) has been extensively uses in general anesthesia and reported to cause deoxyribonucleic acid (DNA) damage in prolonged surgical procedures. Dexmedetomidine (DEX) is an adrenergic agonist and having antioxidant activity that may reduce the genotoxic potential (DNA damage) and oxidative stress induced by ISO in patients undergoing major neurosurgical procedures. Methods and Findings. Twenty-four patients of ASA (American Society of Anesthesiologists) classes I and II were randomly divided into two groups (n = 12). Group A patients received ISO, while group B patients received DEX infusion for maintenance of anesthesia. Venous blood samples were collected at different time intervals and used to evaluate the oxidative stress marker malondialdehyde (MDA) and endogenous antioxidants superoxide dismutases (SOD) and catalases (CAT). A single-cell gel electrophoresis (SCGE)-comet assay was used to investigate the genotoxic potential of ISO.

CONCLUSION

Increased level of antioxidants and decreased value of MDA and genetic damage index were seen in group B (P < 0.001) in a time-dependent manner. Genetic damage was highest at point T ₂ (0.77 vs. 1.37), and continued to decrease till T ₃ (0.42 vs. 1.19), with respect to negative controls or baseline values following DEX infusion. Significantly, higher level of MDA was recorded in serum of group A (P < 0.001) as compared to group B (1.60 ± 0.33 vs. 0.03 ± 0.001). Enzymatic activities of CAT and SOD were significantly higher in group B than group A (10.11 ± 2.18 vs. 5.71 ± 0.33), (1.04 ± 0.05 vs. 0.95 ± 0.01), respectively. It may play a contributing role in daily anesthesia practice and improve the toxic effects on patients as well as anesthesia personnel. Trial Registration. Ethical Committee of Post Graduate Medical Institute (PGMI), Lahore General Hospital approved the use of humans in this study vide human subject application number ANS-6466 dated February 04, 2019. Furthermore, as the clinical trials required registration from an appropriate registry approved by World Health Organization (WHO), this trail also retrospectively registered at Thai Clinical Trials Registry (an approved WHO registry for clinical trials registration) under reference ID TCTR20211230001 on December 30, 2021.

Effect of dexmedetomidine on intrapulmonary shunt in patients with sevoflurane maintained during one-lung ventilation: A case-control study

BACKGROUND

The effects of dexmedetomidine on the circulatory system are complex. It is difficult to predict its effects on intrapulmonary shunts and hypoxic pulmonary vasoconstriction in patients with one-lung ventilation. This study aimed to investigate the effect of dexmedetomidine on intrapulmonary shunt in patients with sevoflurane during one-lung ventilation.

METHODS

Forty patients requiring thoracoscopic lobectomy were randomly divided into the dexmedetomidine group (Group D, n = 20) and the normal saline group (Group N, n = 20). The arterial partial pressure of oxygen (PaO2), pulmonary shunt fraction (Qs/Qt), mean end-tidal sevoflurane concentration, mean arterial pressure, and heart rate were compared between the 2 groups at 3 time points: (i) after 5 minutes of two-lung ventilation (T0), (ii) after 30 minutes of one-lung ventilation (OLV) (T1), and (iii) after 45 minutes of OLV (T2). The dosage of sevoflurane from the beginning of OLV to T2 was calculated.

RESULTS

There were no significant differences in age, body mass index, and FEV1/FVC between Groups D and N (P > .05). At T0, T1, and T2, the PaO2 levels of Group D and Group N were similar (P > .05), and the PaO2 levels of Group D and Group N decreased after OLV. The Qs/Qt level of Groups D and N were similar at T0 (P > .05), and the level of Groups D and N at T1 and T2 was higher than that at T0. The Qs/Qt of Group D was statistically significantly lower than that of Group N at T1 and T2 (P < .05).

CONCLUSION

Compared with the control group, we found that dexmedetomidine can reduce the intrapulmonary shunt fraction and improve the body's status during OLV.

The hypoxic pulmonary vasoconstriction: From physiology to clinical application in thoracic surgery

More than 70 years after its original report, the hypoxic pulmonary vasoconstriction (HPV) response continues to spark scientific interest on its mechanisms and clinical implications, particularly for anesthesiologists involved in thoracic surgery. Selective airway intubation and one-lung ventilation (OLV) facilitates the surgical intervention on a collapsed lung while the HPV redirects blood flow from the "upper" non-ventilated hypoxic lung to the "dependent" ventilated lung. Therefore, by limiting intrapulmonary shunting and optimizing ventilation-to-perfusion (V/Q) ratio, the fall in arterial oxygen pressure (PaO₂) is attenuated during OLV. The HPV involves a biphasic response mobilizing calcium within pulmonary vascular smooth muscles, which is activated within seconds after exposure to low alveolar oxygen pressure and that gradually disappears upon re-oxygenation. Many factors including acid-base balance, the degree of lung expansion, circulatory volemia as well as lung diseases and patient age affect HPV. Anesthetic agents, analgesics and cardiovascular medications may also interfer with HPV during the perioperative period. Since HPV represents the homeostatic mechanism for regional ventilation-to-perfusion matching and in turn, for optimal pulmonary oxygen uptake, a clear understanding of HPV is clinically relevant for all anesthesiologists.

Organ-Protective Effects and the Underlying Mechanism of Dexmedetomidine

Dexmedetomidine (DEX) is a highly selective α2 adrenergic receptor (α2AR) agonist currently used in clinical settings. Because DEX has dose-dependent advantages of sedation, analgesia, antianxiety, inhibition of sympathetic nervous system activity, cardiovascular stabilization, and significant reduction of postoperative delirium and agitation, but does not produce respiratory depression and agitation, it is widely used in clinical anesthesia and ICU departments. In recent years, much clinical study and basic research has confirmed that DEX has a protective effect on a variety of organs, including the nervous system, heart, lungs, kidneys, liver, and small intestine. It acts by reducing the inflammatory response in these organs, activating antiapoptotic signaling pathways which protect cells from damage. Therefore, based on wide clinical application and safety, DEX may become a promising clinical multiorgan protection drug in the future. In this article, we review the physiological effects related to organ protection in α2AR agonists along with the organ-protective effects and mechanisms of DEX to understand their combined application value.

Application of dexmedetomidine for lung injury in elderly patients undergoing one-lung ventilation

Introduction

This study aimed to evaluate the effects of dexmedetomidine (DEX) on lung injury, the oxygenation index and perioperative pulmonary complications in elderly patients who underwent thoracotomy with one-lung ventilation (OLV).

Material and methods

A total of 120 elderly patients with lung cancer were included in the present study. According to the random number table method, these patients were randomly divided into two groups: group D and group C. Patients in group D were intravenously pumped with 0.5 μg/kg/h of DEX before anesthesia. The infusion was completed within 15 min, and anesthesia was induced by venous injection. Patients in group C were pumped with equal volumes of normal saline.

Results

At T2 and T3, compared with group C, group D had a significant decrease in cardiac index, mean arterial pressure and central venous pressure (p < 0.05). At T2, T3 and T4, compared with group C, group D had a significant increase in pH and PaO2 (p < 0.05). At T2, T3 and T4, compared with group C, group D had a significant decrease in Qs/Qt (p < 0.05). At T6, compared with group C, group D had a significant decrease in the supernatant of bronchoalveolar lavage fluid of tumor necrosis factor-α and interleukin 6 (p < 0.05). At T5, compared with group C, group D had a significant decrease in Visual Analogue Scale score (p < 0.05), and a significant increase in Ramsay Sedation Scale score (p < 0.05), and the number of respiratory and cardiovascular events also decreased (p < 0.05).

Conclusions

In elderly patients, dexmedetomidine can reduce Qs/Qt and increase PaO2 during OLV in surgery. It can reduce lung injury. Moreover, DEX reduced respiratory and cardiovascular complications in the perioperative period.

Effect of Dexmedetomidine Combined with Inhalation of Isoflurane on Oxygenation Following One-Lung Ventilation in Thoracic Surgery

Background

One-lung ventilation (OLV) is commonly used during thoracic surgery. At this time, hypoxemia is considered one of the remarkable consequences of the anesthesia management. Hypoxic pulmonary vasoconstriction (HPV) is the defense mechanism against hypoxia.

Objectives

The aim of the present study was to investigate the effect of infusion of dexmedetomidine on improving the oxygenation during OLV among the adult patients undergoing thoracic surgery.

Methods

A total of 42 patients undergoing OLV by general anesthesia with isoflurane inhalation were randomly assigned into two groups: IV infusion of dexmedetomidine at 0.3 microgram/kg/h (DISO) and IV infusion of normal saline (NISO). Three Arterial Blood Gas (ABG) samples were obtained throughout the surgery. Hemodynamic parameters, PaO₂, PaCO₂, and complications at recovery phase were recorded. The collected information was analyzed using SPSS software version 22.

Results

In the dexmedetomidine group, the mean hemodynamic parameters had a significant reduction at 30 and 60 minutes following OLV. Administration of dexmedetomidine resulted in a significant increase in the PaCO₂ and a reduction in the PaO₂ when changing from two-lung ventilation to OLV, where PaO₂ reached its maximum value within 10 minutes after OLV in the DISO group, and it began to gradually increase to the end of operation. The duration of the recovery phase, also complications at the recovery phase decreased significantly in DISO group.

Conclusions

The results of the study showed that, dexmedetomidine may improve arterial oxygenation during OLV in adult patients undergoing thoracic surgery, and can be a suitable anesthetic agent for thoracic surgery.

Effects of dexmedetomidine on oxidative stress and inflammatory response in lungs during mechanical ventilation in COPD rats

Effects of dexmedetomidine (Dex) on oxidative stress and inflammatory response in lungs during mechanical ventilation in chronic obstructive pulmonary disease (COPD) rats were investigated. Eleven out of 38 SD rats were randomly selected as the blank control group, and the other 27 rats were subjected to modeling. After the modeling, 11 rats in the blank control group and 11 rats randomly selected from the model group received non-invasive test for lung function. Three rats from the blank control group and 3 rats from the model group were selected for hematoxylin and eosin (HE) staining to confirm successful modeling, and the other 24 rats were randomly divided into 3 groups, 8 rats in each group, including model control, Dex low-dose and Dex high-dose group. A COPD rat model was established by passive cigarette smoking and intratracheal instillation of lipopolysaccharide. Each group underwent mechanical ventilation for 2 h. The Dex low-dose group and Dex high-dose group were intravenously administered at 1.0 µg/kg/h and 5.0 µg/kg/h of Dex, and the other two groups received intravenous drip of the same amount of normal saline. Blood gas analysis was performed to calculate carbon dioxide partial pressure (PaCO₂), oxygen partial pressure (PaO₂) and blood pH. HE staining was performed to analyze pulmonary pathological features of COPD rat model. Serum inflammatory factors interleukin-8 (IL-8), tumor necrosis factor-alpha (TNF-α) and malondialdehyde (MDA) were detected by ELISA, and the levels of antioxidant enzymes superoxide dismutase 2 (SOD2) and catalase were analyzed by western blot analysis. After 28 days of modeling, TV, PEF, FEV0.3 and FEV0.3/FVC decreased significantly in the COPD model group. HE staining showed that in the model group, the alveolar cells became larger, the alveolar wall became thinner, and some alveolar walls were even broken. The lung lobule showed obvious cell degeneration, necrosis and shedding, and the interstitial inflammatory cell infiltration, suggesting that the COPD rat model was successfully established. After 2 h of mechanical ventilation and Dex intravenous infusion, PaCO₂ decreased, PaO₂ increased, and blood pH value increased (p<0.05). Inflammatory factors IL-8 and TNF-α decreased (p<0.05). Oxidative stress index MDA also decreased (p<0.05), antioxidant enzymes SOD2 and catalase increased (p<0.05). Dexmedetomidine can improve the oxidative stress response during mechanical ventilation in rats with COPD, and can reduce the inflammation of lung tissue, thus protecting the lung tissue of COPD rats.

Dexmedetomidine attenuates oxidative/nitrative stress in lung tissues of septic mice partly via activating heme oxygenase-1

Excessive reactive oxygen/nitrogen species are considered to be one of the primary events that cause lung injury during sepsis. The present study aimed to determine whether dexmedetomidine (Dex) exhibits antioxidative and antinitrative effects on sepsis-induced lung injury and its effect on heme oxygenase-1 (HO-1) activation. The cecal ligation and puncture (CLP) mouse model was used, where male C57BL/6J mice were randomized into groups: Sham, CLP, Dex and Dex + zinc protoporphyrin (ZnPP). Following CLP or sham operation, intraperitoneal injections of 40 µg/kg Dex or saline were administered in the Dex + ZnPP group, intraperitoneal injections of ZnPP (40 mg/kg) were administered 1 h prior to the CLP operation. Subsequently, histopathological examination of the lungs and measurement of HO-1 activity in the lung, as well as oxidative and nitrative stress were determined 24 h following CLP. Dex significantly decreased the levels of oxidative and nitrative stress, as demonstrated by the decreased levels of malondialdehyde and nitrotyrosine, and the protein expression of inducible nitric oxide synthase, as well as increased superoxide dismutase in lung tissues. Also Dex inhibited the elevation of serum interleukin-6 and tumor necrosis factor-α and increased lung HO-1 activity. Furthermore, the effects of Dex were partially reverted by the HO-1 inhibitor ZnPP. In conclusion, Dex inhibited oxidative/nitrative stress in sepsis and attenuated sepsis-induced acute lung injury partially by increasing HO-1 activity.

Protective effect of nicorandil on collapse‑induced lung injury in rabbits by inhibiting apoptosis

The one‑lung ventilation (OLV) technique is vital in thoracic surgery. However, it can result in severe lung injury, which is difficult to manage. The main solution at present is the use of ventilation strategies, including continuous positive oxygen pressure, low tidal volume and high frequency ventilation, and the administering of drugs, including phenylephrine, dexmedetomidine and morphine. However, the protective effect of these methods on the lungs is not sufficient to improve the prognosis of patients. Therefore, how to develop a novel protective drug remains an open question. Nicorandil, a mitochondrial (mito)KATP‑specific opener, serves an important role in cardioprotection, although its effect on lung injury remains unclear. The present study examined the protective role of nicorandil against collapse‑induced lung injury in rabbits undergoing OLV. Changes in arterial oxygen saturation (SaO2), arterial partial pressure for oxygen (PaO2), wet/dry weight ratio, and the microstructure of tissues and cells were observed. Enzyme‑linked immunosorbent assays were used to determine the concentrations of malondialdehyde (MDA) and tumor necrosis factor (TNF)‑α, and the activity of superoxide dismutase (SOD) in rabbits treated with nicorandil. Terminal deoxynucleotidyl transferase transfer‑mediated dUTP nick end‑labeling was used to detect apoptosis and western blotting was used to analyze the relative proteins involved in apoptosis. Western blotting and reverse transcription‑quantitative polymerase chain reaction analysis were used to examine the expression of hypoxia inducible factor 1α (HIF‑1α), phosphatidylinositol‑3‑kinase (PI3K), protein kinase B (Akt) and nuclear factor (NF)‑κB in the lungs of rabbits treated with nicorandil. The SaO2 and PaO2 in the high‑dose group were significantly higher than those in the control group in the process of OLV. The wet/dry weight ratio, and the concentrations of MDA and TNF‑α in the collapsed lung of the high‑dose group were significantly lower than those in the control group. The activity of SOD in the high‑dose group was significantly higher than that in the control group. The lung had improved microstructure and less apoptosis, which was determined by the Bax/Bcl2 ratio in the high‑dose group. The expression levels of PI3K, phosphorylated Akt and HIF‑1α were upregulated, whereas the expression of NF‑κB was downregulated. In conclusion, nicorandil had a protective effect via inhibiting apoptosis in non‑ventilated lung collapsed and re‑expansion during OLV in the rabbit. It acted on mitoKATP through the PI3K/Akt signaling pathway.

Effects of epidural anesthesia combined with inhalation anesthesia or intravenous anesthesia on intrapulmonary shunt and oxygenation in patients undergoing long term single lung ventilation

Objective:

To investigate the effect of epidural anesthesia combined with inhalation or intravenous anesthesia on intrapulmonary shunt and oxygenation in patients undergoing long term single lung ventilation.

Methods:

Eighty patients, aged 35-75, American Society of Anesthesiology (ASA) classification of I-III, undergoing thoracic surgery with one lung ventilation more than three hour, were randomly divided into propofol group (group Pro), propofol combined with epidural anesthesia group (group Pro+Epi), isoflurane group (group Iso) and isoflurane combined with epidural anesthesia group (group Iso+ Epi), 20 patients in each group. Arterial blood and mixed venous blood were taken for blood gas analysis, and hemodynamic data were recorded at following time points: before induction in supine position (T₁), 30min after bilateral lung ventilation (T₂), 15min after one lung ventilation (T₃), 30min after one lung ventilation (T4), 60min after one lung ventilation (T5), 180min after one lung ventilation (T6), intrapulmonary shunt (Qs/Qt) was calculated according to the correlation formula.

Results:

Qs/Qt values at T_2-6 in four groups were significantly higher than that of T1, and Qs/Qt values at T_3-6 was significantly higher than that of T₂ (P< 0.05); PaO2 at T_2-6 were significantly higher than that of T1, with PaO2 at T_3-6 were significantly lower than T₂ (P< 0.05). Between groups, Qs/Qt values in group Iso were significantly higher than that of group Pro, Pro+Epi and Iso+Epi at T_3-5 (P< 0.05). There was no significant difference in PaO₂ between groups (P> 0.05). CI at T3-6 in group Iso and Iso+Epi were significantly higher than that of T₁ (P<0.05), and were significantly higher than that of propofol group (P<0.05). MAP at T_3-6 in group Pro+Epi and Iso+Epi were significantly lower than that at T₁ (P <0.05). Heart rate at T_4-6 in group Iso were significantly higher than T₁, and higher than group Pro and group Iso+Epi (P <0.05).

Conclusion:

One lung ventilation may predispose to increase of intrapulmonary shunt and decrease in arterial partial pressure of oxygen; isoflurane inhalation anesthesia is more likely to cause intrapulmonary shunt, but no changes in arterial partial pressure of oxygen.

Evaluation of the effects of dexmedetomidine infusion on oxygenation and lung mechanics in morbidly obese patients with restrictive lung disease

Background

Dexmedetomidine infusion improves oxygenation and lung mechanics in patients with chronic obstructive lung disease; however, its effect in patients with restrictive lung disease has not been thoroughly investigated yet. The aim of this work was to evaluate the effects of dexmedetomidine infusion on oxygenation and lung mechanics in morbidly obese patients with restrictive lung disease.

Methods

Forty-two morbidly obese patients scheduled for bariatric surgery were included in the study. Patients were randomized to receive either dexmedetomidine infusion at a bolus dose of 1mcg/Kg followed by infusion at 1 mcg/Kg/hour for 90 min (Dexmedetomidine group), or normal saline infusion (Control group). Both groups were compared with regard to: oxygenation {P/F ratio: PaO₂/fraction of inspired oxygen (FiO₂)}, lung compliance, dead space, plateau pressure, blood pressure, and heart rate.

Results

Dexmedetomidine group showed significant improvement of the PaO₂/FiO₂ ratio, and higher lung compliance compared to control group by the end of drug infusion. Dexmedetomidine group demonstrated decreased dead space, plateau pressure, blood pressure, and heart rate compared to control group by the end of drug infusion.

Conclusion

A 90-min dexmedetomidine infusion resulted in moderate improvement in oxygenation and lung mechanics in morbidly obese patients with restrictive lung disease.

Trial registration

clinicaltrials.gov: NCT02843698 on 20 July 2016.

Paravertebral dexmedetomidine as an adjuvant to ropivacaine protects against independent lung injury during one-lung ventilation: a preliminary randomized clinical trial

Background

To investigate the effect of paravertebral dexmedetomidine as an adjuvant to ropivacaine on independent lung injury during one-lung ventilation.

Methods

In total, 120 patients who underwent elective radical resection of pulmonary carcinoma were randomly assigned to one of six groups (n = 20): normal saline (C group), ropivacaine (R group), intravenous dexmedetomidine (Div group), 0.5 μg/kg paravertebral dexmedetomidine as an adjuvant to ropivacaine (RD0.5 group), 1.0 μg/kg paravertebral dexmedetomidine as an adjuvant to ropivacaine (RD1.0 group), or 2.0 μg/kg paravertebral dexmedetomidine as an adjuvant to ropivacaine (RD2.0 group).

Patients in the R, Div, RD0.5, RD1.0 and RD2.0 groups underwent a thoracic paravertebral block, and normal saline was administered as a control to C group. Small marginal lung samples next to the tumor were harvested immediately after the tumor tissues were excised.

Lung injury was evaluated as follows: an injury score was determined via light microscopy, and cell apoptosis was determined via a TUNEL assay. TNF-α, IL-6, miRNA-210, HIF-1α, Tom20 and ISCU2 were also detected.

Results

Both intravenous and paravertebral dexmedetomidine attenuated independent lung injury. Downregulation of HIF-1α and miRNA-210 and upregulation of Tom20 and ISCU2 may be the underlying mechanism. No difference was observed between the Div and RD0.5 groups, and no further improvement of lung injury was found in the RD1.0 and RD2.0 groups with increased paravertebral dexmedetomidine doses.

Conclusions

Paravertebral dexmedetomidine as an adjuvant to ropivacaine, which is comparable to intravenous dexmedetomidine, could protect against independent lung injury during one-lung ventilation.

Trial registration

ISRCTN, 13000406; retrospectively registered on 22.05.2018.

Can Dexmedetomidine Improve Arterial Oxygenation and Intrapulmonary Shunt during One-lung Ventilation in Adults Undergoing Thoracic Surgery? A Meta-analysis of Randomized, Placebo-controlled Trials

Background:

One-lung ventilation (OLV) is a common ventilation technology during thoracic surgery that can cause serious clinical problems. We aimed to conduct a meta-analysis to compare oxygenation and intrapulmonary shunt during OLV in adults undergoing thoracic surgery with dexmedetomidine (Dex) versus placebo to assess the influence and safety of using Dex.

Methods:

Randomized controlled trials comparing lung protection in patients who underwent thoracic surgery with Dex or a placebo were retrieved from PubMed, EMBASE, MEDLINE, Cochrane Library, and China CNKI database. The following information was extracted from the paper: arterial oxygen partial pressure (PaO₂), PaO₂/inspired oxygen concentration (PaO₂/FiO₂, oxygenation index [OI]), intrapulmonary shunt (calculated as Qs/Qt), mean arterial pressure (MAP), heart rate (HR), tumor necrosis factor-α (TNF-α), interleukin (IL)-6, superoxide dismutase (SOD), and malondialdehyde (MDA).

Results:

Fourteen randomized controlled trials were included containing a total of 625 patients. Compared with placebo group, Dex significantly increased PaO₂/FiO₂ (standard mean difference [SMD] = 0.98, 95% confidence interval [CI] [0.72, 1.23], P < 0.00001). Besides, Qs/Qt (SMD= −1.22, 95% CI [−2.20, −0.23], P = 0.020), HR (SMD= −0.69, 95% CI [−1.20, 0.17], P = 0.009), MAP (SMD= −0.44, 95% CI [−0.84, 0.04], P = 0.030), the concentrations of TNF-α (SMD = −1.55, 95% CI [−2.16, −0.95], P <0.001), and IL-6 (SMD = −1.53, 95% CI [−2.37, −0.70], P = 0.0003) were decreased in the treated group, when compared to placebo group. No significant difference was found in MDA (SMD = −1.14, 95% CI [−3.48, 1.20], P = 0.340) and SOD (SMD = 0.41, 95% CI [−0.29, 1.10], P = 0.250) between the Dex group and the placebo group. Funnel plots did not detect any significant publication bias.

Conclusions:

Dex may improve OI and reduce intrapulmonary shunt during OLV in adults undergoing thoracic surgery. However, this conclusion might be weakened by the limited number of pooled studies and patients.

Use of Dexmedetomidine in Cardiothoracic and Vascular Anesthesia

Dexmedetomidine is a highly selective α₂-adrenergic agonist with analgesic and sedative properties. In the United States, the Food and Drug Administration approved the use of the drug for short-lasting sedation (24 h) in intensive care units (ICUs) in patients undergoing mechanical ventilation and endotracheal intubation. In October 2008, the Food and Drug Administration extended use of the drug for the sedation of nonintubated patients before and during surgical and nonsurgical procedures. In the European Union, the European Medicine Agency approved the use of dexmedetomidine in September 2011 with a single recognized indication: ICU adult patients requiring mild sedation and awakening in response to verbal stimulus. At present, the use of dexmedetomidine for sedation outside the ICU remains an off-label indication. The benefits of dexmedetomidine in critically ill patients and in cardiac, electrophysiology-related, vascular, and thoracic procedures are discussed.

Suppression of nuclear factor erythroid‑2‑related factor 2‑mediated antioxidative defense in the lung injury induced by chronic exposure to methamphetamine in rats

The imbalance between oxidative stress and antioxidant defense is important in the pathogenesis of lung diseases. Nuclear factor erythroid‑2‑related factor 2 (Nrf2) is a key transcriptional factor that regulates the antioxidant response. The purpose of the present study was to investigate whether Nrf2‑mediated antioxidative defense is involved in methamphetamine (MA)‑induced lung injury in rats. Following establishment of chronic MA toxicity in rats, Doppler ultrasonic detection was used to measure the changes of physiological indexes, followed by hematoxylin and eosin staining, ELISA and western blot analysis. MA was demonstrated to increase the heart rate and peak blood flow velocity of pulmonary arterial valves and to decrease the survival rate of rats, and resulted in lung injury characterized by perivascular exudates, airspace edema, slight hemorrhage and inflammatory cell infiltration. MA significantly inhibited the expression of nuclear Nrf2 protein and its target genes (glutamate‑cysteine ligase catalytic subunit C and heme oxygenase‑1), and dose‑dependently reduced glutathione (GSH) levels and the ratio of GSH/oxidized glutathione, accompanied by increases in reactive oxygen species (ROS) levels in rat lungs. Linear regression analysis revealed that there was a positive correlation between lung ROS level and lung injury indexes. These findings suggested that chronic exposure to MA led to lung injury by suppression of Nrf2‑mediated antioxidative defense, suggesting that Nrf2 may be an important therapeutic target for MA‑induced chronic lung toxicity.

Interactions of nitric oxide with α2 -adrenoceptors within the locus coeruleus underlie the facilitation of inhibitory avoidance memory by agmatine

BACKGROUND AND PURPOSE

Agmatine, a putative neurotransmitter, plays a vital role in learning and memory. Although it is considered an endogenous ligand of imidazoline receptors, agmatine exhibits high affinity for α-adrenoceptors, NOS and NMDA receptors. These substrates within the locus coeruleus (LC) are critically involved in learning and memory processes.

EXPERIMENTAL APPROACH

The hippocampus and LC of male Wistar rat were stereotaxically cannulated for injection. Effects of agmatine, given i.p. or intra-LC, on acquisition, consolidation and retrieval of inhibitory avoidance (IA) memory were measured. The NO donor S-nitrosoglutathione, non-specific (L-NAME) and specific NOS inhibitors (L-NIL, 7-NI, L-NIO), the α2 -adrenoceptor antagonist (yohimbine) or the corresponding agonist (clonidine) were injected intra-LC before agmatine. Intra-hippocampal injections of the NMDA antagonist, MK-801 (dizocilpine), were used to modify the memory enhancing effects of agmatine, SNG and yohimbine. Expression of tyrosine hydroxylase (TH) and eNOS in the LC was assessed immunohistochemically.

KEY RESULTS

Agmatine (intra-LC or i.p.) facilitated memory retrieval in the IA test. S-nitrosoglutathione potentiated, while L-NAME and L-NIO decreased, these effects of agmatine. L-NIL and 7-NI did not alter the effects of agmatine. Yohimbine potentiated, whereas clonidine attenuated, effects of agmatine within the LC. The effects of agmatine, S-nitrosoglutathione and yohimbine were blocked by intra-hippocampal MK-801. Agmatine increased the population of TH- and eNOS-immunoreactive elements in the LC.

CONCLUSIONS AND IMPLICATIONS

The facilitation of memory retrieval in the IA test by agmatine is probably mediated by interactions between eNOS, NO and noradrenergic pathways in the LC.

α2-adrenoreceptor modulated FAK pathway induced by dexmedetomidine attenuates pulmonary microvascular hyper-permeability following kidney injury

Renal ischemia-reperfusion (rI/R) could cause remote acute lung injury (ALI) and combination of these two organ injuries can remarkably increase the mortality. This study aims to determine whether dexmedetomidine, an α2-adrenoreceptor agonist sedative, can ameliorate pulmonary microvascular hyper-permeability following rI/R injury and explore the underlying mechanisms. In vivo, C57BL/6J mice received dexmedetomidine (25µg/kg, i.p.) in the absence or presence of α2-adrenergic antagonist atipamezole (250µg/kg, i.p.) or focal adhesion kinase (FAK) inhibitor (30mg/kg, i.p.) before bilateral renal pedicle clamping for 45 minutes followed by 24 hours reperfusion. The lung histopathological changes and the permeability of pulmonary microvascular were assessed respectively. In vitro, the cultured C57BL/6J mice pulmonary microvascular endothelial cells (PMVECs) were treated with serum from mice with rI/R with or without dexmedetomidine and atipamezole. Trans-endothelial permeability and phospho-tyrosine397FAK, F-actin, VE-cadherin and ZO-1 in monolayer PMVECs were measured respectively in the presence or absence of rI/R serum, dexmedetomidine and FAK inhibitor. In vivo, dexmedetomidine remarkably attenuated lung injury and pulmonary microvascular hyper-permeability caused by rI/R injury, which was abolished by atipamezole or FAK inhibitor co-administration. In vitro, the permeability of PMVECs monolayer following exposure to serum from rI/R mice was increased significantly, and decreased by dexmedetomidine. Dexmedetomidine increased phospho-tyrosine397FAK in a time- and dose-dependent manner, which was correlated with the changes in trans-endothelial permeability. Our data indicated that dexmedetomidine is able to ameliorate remote pulmonary microvascular hyper-permeability induced by rI/R, at least in part, via FAK modulation.