The role of neuronal NO synthase in the respiratory effects of TNF-α

It was shown that an increase level of proinflammatory cytokines has a modulating effect on the reflex control of respiration. The aim of this study was to investigate the involvement of neuronal nitric oxide synthase (nNOS) in the mechanisms of the influence of an increased level of Tumor necrosis factor – α (TNF-α) on the hypoxic ventilatory response. To achieve this goal, experiments were carried out on urethane anesthetized rats with intravenous administration of TNF-α before and after pretreatment with 7-nitroindazole specific nNOS inhibitor. The hypoxic ventilation response was assessed by rebreathing with a hypoxic gas mixture before and after administration of TNF-α. We found that TNF-α decreased the ventilatory response to hypoxia. Pretreatment with nNOS inhibitor reduced respiratory effects of TNF-α. Key words: cytokines, TNF-α, hypoxia, chemoreflex, respiration, ventilation, neuronal nitric oxide synthase.

The role of prostaglandins in the realization of respiratory effects of TNF-α in case of hypoxia

At the present time very little is known about interactions between systemic inflammation and control of respiration. The aim of this study was to compare the respiratory effects of the main inflammatory cytokine TNF - α before and after pretreatment with diclofenac, a nonspecific cyclooxygenase (COX) inhibitor. In experiments on anesthetized, tracheostomized rats, pneumotachometry method was used to measure peak airflow and respiratory rate. The ventilatory response to hypoxia was investigated by the rebreathing method. It is shown that an increase in the systemic level of TNF – α causes a significant increase in the minute volume of respiration, tidal volume, the average speed of the inspiratory flow. In contrast the slope of the hypoxic ventilatory response decreased after administration of TNF-α. Diclofenac pretreatment eliminated these respiratory effects of TNF - α. The data indicate that the ability of TNF - α to enhance basal ventilation and to reduce the ventilatory hypoxic response is mediated by the cyclooxygenase pathway. Key words: tumor necrosis factor – α, hypoxia, prostaglandins, peripheral chemoreception, respiration.

Environmental and Occupational Short-Term Exposure to AirBorne Particles and FEV1 and FVC in Healthy Adults: A Systematic Review and Meta-Analysis

Background: No study has compared the respiratory effects of environmental and occupational particulate exposure in healthy adults. Methods: We estimated, by a systematic review and meta-analysis, the associations between short term exposures to fine particles (PM2.5 and PM4) and certain parameters of lung function (FEV1 and FVC) in healthy adults. Results: In total, 33 and 14 studies were included in the qualitative synthesis and meta-analyses, respectively. In environmental studies, a 10 µg/m3 increase in PM2.5 was associated with an FEV1 reduction of 7.63 mL (95% CI: −10.62 to −4.63 mL). In occupational studies, an increase of 10 µg/m3 in PM4 was associated with an FEV1 reduction of 0.87 mL (95% CI: −1.36 to −0.37 mL). Similar results were observed with FVC. Conclusions: Both occupational and environmental short-term exposures to fine particles are associated with reductions in FEV1 and FVC in healthy adults.

Investigating the Association between Wake-Up Stroke and Obstructive Sleep Apnea: A Meta-Analysis

<b><i>Background:</i></b> Management of wake-up stroke (WUS) is always a challenge as no clear time of onset could be ascertained, and how to choose an appropriate therapy remains unclear. Sleep-disordered breathing (SDB) has been regarded as a potential risk factor to WUS, yet no consensus was achieved. Motivated by the need for a deeper understanding of WUS and its association with sleep apnea, meta-analyses summarizing the available evidence of respiratory events and indices were conducted, and sensitivity analysis was also used for heterogeneity. <b><i>Methods:</i></b> Electronic databases were systematically searched, and cross-checking was done for relevant studies. Collected data included demographic characteristics, and sleep apnea parameters were extracted with stroke patients divided into WUS and NWUS groups. Clinical data of stroke patients accompanied with sleep apnea syndrome (OSA, SAS, and severe SAS) were also extracted for meta-analysis. <b><i>Results:</i></b> A total of 13 studies were included in the analysis. The meta-analysis results showed that OSA, SAS, and severe SAS were significantly higher in WUS patients. A significantly higher AHI (WMD 7.74, 95% CI: 1.38–14.11; <i>p</i> = 0.017) and ODI (WMD of 3.85, 95% CI: 0.261–7.438; <i>p</i> = 0.035) than NWUS patients was also observed in the analysis of respiratory indices. <b><i>Conclusion:</i></b> WUS patients have severer SDB problems compared to NWUS patients suggesting that respiratory events during sleep might be underlying the induction of WUS. Besides, the induction of WUS was significantly associated with men rather than women. Therefore, early diagnosis and management of potential WUS patients should benefit from the detection of SDB status and respiratory effects.

Comparison of Respiratory Effects between Dexmedetomidine and Propofol Sedation for Ultrasound-Guided Radiofrequency Ablation of Hepatic Neoplasm: A Randomized Controlled Trial

Patient’s cooperation and respiration is necessary in percutaneous radiofrequency ablation (RFA) for hepatocellular carcinoma (HCC). We compared the respiratory patterns of dexmedetomidine and propofol sedation during this procedure. Participants were randomly allocated into two groups: the continuous infusions of dexmedetomidine-remifentanil (DR group) or the propofol-remifentanil (PR group). We measured the tidal volume for each patient’s respiration during one-minute intervals at five points and compared the standard deviation of the tidal volumes (SDvt) between the groups. Sixty-two patients completed the study. SDvt at 10 min was not different between the groups (DR group, 108.58 vs. PR group, 149.06, p = 0.451). However, SDvt and end-tidal carbon dioxide (EtCO2) level of PR group were significantly increased over time compared to DR group (p = 0.004, p = 0.021; ß = 0.14, ß = −0.91, respectively). Heart rate was significantly decreased during sedation in DR group (p < 0.001, ß = −2.32). Radiologist satisfaction was significantly higher, and the incidence of apnea was lower in DR group (p = 0.010, p = 0.009, respectively). Compared with propofol-remifentanil, sedation using dexmedetomidine-remifentanil provided a lower increase of the standard deviation of tidal volume and EtCO2, and also showed less apnea during RFA of HCC.