Lauric acid alleviates inflammation and structural changes in the lungs of type II diabetic male Wistar rats

Lauric acid is a medium-chain fatty acid that has been reported to possess anti-inflammatory, antioxidant and antibacterial properties. Diabetic complication in the lungs is characterized by infiltration of inflammatory mediators and structural alteration of the lung parenchyma. This study was designed to evaluate the effect of lauric acid on leucocytes infiltration in bronchoalveolar lavage fluid (BALF), concentration of tumor necrosis factor-α and lung histology of type II diabetic male Wistar rats. A total of thirty-five male Wistar rats were randomly divided into seven groups of five rats each as follows: Group I served as normal control; group II were normoglycemic rats, administered 125 mg/Kg bwt lauric acid. Group III served as diabetic control. Groups IV, V, VI and VII were diabetic Wistar rats treated with 125 mg/Kg bwt, 250 mg/Kg bwt, 500 mg/Kg bwt lauric acid and 100 mg/Kg bwt metformin respectively. The results obtained, showed a significant (P ≤ 0.05) increase in total white blood cell count and differential count of lymphocytes, neutrophils and macrophages in blood and BALF of the diabetic control compared to the normal control. However, there was a significant decrease in total and  differential white blood cell count in blood and BALF of the diabetic groups treated with lauric acid compared to the diabetic control (P ≤ 0.05). The concentration of TNF-α was significantly higher in the lungs of diabetic rats compared to the normal control, but the concentration was significantly reduced after treatment with lauric acid (P ≤ 0.05). Lauric acid also reversed the reduced alveolar spaces in diabetic lungs. These results indicate that lauric acid reduced inflammation and reversed the histoarchitectural alterations in the lungs of type II diabetic male Wistar rats.Keywords: Lauric acid, Type II diabetes, Hyperglycemia, Lungs, Pneumopathy,Leucocytes infiltration, Inflammation, Wistar rat

Early rise in central venous pressure during a spontaneous breathing trial: A promising test to identify patients at high risk of weaning failure?

Background The spontaneous breathing trial (SBT) assesses the risk of weaning failure by evaluating some physiological responses to the massive venous return increase imposed by discontinuing positive pressure ventilation. This trial can be very demanding for some critically ill patients, inducing excessive physical and cardiovascular stress, including muscle fatigue, heart ischemia and eventually cardiac dysfunction. Extubation failure with emergency reintubation is a serious adverse consequence of a failed weaning process. Some data suggest that as many as 50% of patients that fail weaning do so because of cardiac dysfunction. Unfortunately, monitoring cardiovascular function at the time of the SBT is complex. The aim of our study was to explore if central venous pressure (CVP) changes were related to weaning failure after starting an SBT. We hypothesized that an early rise on CVP could signal a cardiac failure when handling a massive increase on venous return following a discontinuation of positive pressure ventilation. This CVP rise could identify a subset of patients at high risk for extubation failure. Methods Two-hundred and four mechanically ventilated patients in whom an SBT wa

Non-invasive phrenic nerve stimulation to avoid ventilator-induced diaphragm dysfunction in critical care

Background: Diaphragm muscle atrophy during mechanical ventilation begins within 24 h and progresses rapidly with significant clinical consequences. Electrical stimulation of the phrenic nerves using invasive electrodes has shown promise in maintaining diaphragm condition by inducing intermittent diaphragm muscle contraction. However, the widespread application of these methods may be limited by their risks as well as the technical and environmental requirements of placement and care. Non-invasive stimulation would offer a valuable alternative method to maintain diaphragm health while overcoming these limitations. Methods: We applied non-invasive electrical stimulation to the phrenic nerve in the neck in healthy volunteers. Respiratory pressure and flow, diaphragm electromyography and mechanomyography, and ultrasound visualization were used to assess the diaphragmatic response to stimulation. The electrode positions and stimulation parameters were systematically varied in order to investigate the influence of these parameters on the ability to induce diaphragm contraction with non-invasive stimulation. Results: We demonstrate that non-invasive capture of the phrenic nerve is feasible using surface electrodes without the application of pressure, and characterize the stimulation parameters required to achieve therapeutic diaphragm contractions in healthy volunteers. We show that an optimal electrode position for phrenic nerve capture can be identified and that this position does not vary as head orientation is changed. The stimulation parameters required to produce a diaphragm response at this site are characterized and we show that burst stimulation above the activation threshold reliably produces diaphragm contractions sufficient to drive an inspired volume of over 600 ml, indicating the ability to produce significant diaphragmatic work using non-invasive stimulation. Conclusion: This opens the possibility of non-invasive systems, requiring minimal specialist skills to set up, for maintaining diaphragm function in the intensive care setting

Effect of high dose verapamil administration on the Ca2+ channel density in rat cardiac tissue

NRC publication: Ye

Sensitivity of 24-h EMG duration and intensity in the human vastus lateralis muscle to threshold changes

Few studies have quantified lower limb muscle activity over 24 h using electromyographic signals (EMG). None have described the changes in EMG duration and intensity when data are analyzed with different thresholds. Continuous bilateral EMG recordings were made from vastus lateralis (VL) in 10 subjects (20–48 yr) for 24 h. Before and after this recording, voluntary quadriceps forces and VL EMG at 25%, 50%, 75%, and 100% of the maximal voluntary contraction (MVC), percentage voluntary activation (twitch interpolation), and compound action potentials (M-waves) were recorded. Offline, the 24-h EMG integrals (IEMG, 10-ms time constant) were normalized to the MVC IEMG. Total EMG duration and mean IEMG ranged from 1–3 h and 3.2–12.1% MVC, respectively, when the data were analyzed using the baseline (+3 SD) as threshold. When analysis was done with progressively higher thresholds, from baseline up to 4% MVC, the total EMG duration declined curvilinearly. In some cases the decline in duration was 50–60% for a 1% MVC threshold increment. The mean 24-h IEMG increased by 1.5–2% MVC for each 1% MVC threshold increment. Hence, a small change in the analysis threshold may result in large changes in 24-h EMG duration but moderate changes in mean IEMG. Our findings suggest that VL was active for a short amount of time and at low intensities over 24 h

Non-invasive phrenic nerve stimulation to avoid ventilator-induced diaphragm dysfunction in critical care

Background Diaphragm muscle atrophy during mechanical ventilation begins within 24 h and progresses rapidly with significant clinical consequences. Electrical stimulation of the phrenic nerves using invasive electrodes has shown promise in maintaining diaphragm condition by inducing intermittent diaphragm muscle contraction. However, the widespread application of these methods may be limited by their risks as well as the technical and environmental requirements of placement and care. Non-invasive stimulation would offer a valuable alternative method to maintain diaphragm health while overcoming these limitations. Methods We applied non-invasive electrical stimulation to the phrenic nerve in the neck in healthy volunteers. Respiratory pressure and flow, diaphragm electromyography and mechanomyography, and ultrasound visualization were used to assess the diaphragmatic response to stimulation. The electrode positions and stimulation parameters were systematically varied in order to investigate the influence of these parameters on the ability to induce diaphragm contraction with non-invasive stimulation. Results We demonstrate that non-invasive capture of the phrenic nerve is feasible using surface electrodes without the application of pressure, and characterize the stimulation parameters required to achieve therapeutic diaphragm contractions in healthy volunteers. We show that an optimal electrode position for phrenic nerve capture can be identified and that this position does not vary as head orientation is changed. The stimulation parameters required to produce a diaphragm response at this site are characterized and we show that burst stimulation above the activation threshold reliably produces diaphragm contractions sufficient to drive an inspired volume of over 600 ml, indicating the ability to produce significant diaphragmatic work using non-invasive stimulation. Conclusion This opens the possibility of non-invasive systems, requiring minimal specialist skills to set up, for maintaining diaphragm function in the intensive care setting