Predictive value of diaphragm ultrasound for mechanical ventilation outcome in patients with acute exacerbation of chronic obstructive pulmonary disease

BACKGROUND Acute exacerbation of chronic obstructive pulmonary disease(AECOPD)is often combined with respiratory failure,which increases the patient's morbidity and mortality.Diaphragm ultrasound(DUS)has developed rapidly in the field of critical care in recent years.Studies with DUS monitoring diaphragm-related rapid shallow breathing index have demonstrated important results in guiding intensive care unit patients out of the ventilator.Early prediction of the indications for withdrawal of non-invasive ventilator and early evaluation of patients to avoid or reduce disease progression are very important.AIM To explore the predictive value of DUS indexes for non-invasive ventilation outcome in patients with AECOPD.METHODS Ninety-four patients with AECOPD who received mechanical ventilation in our hospital from January 2022 to December 2023 were retrospectively analyzed,and they were divided into a successful ventilation group(68 cases)and a failed ventilation group(26 cases)according to the outcome of ventilation.The clinical data of patients with successful and failed noninvasive ventilation were compared,and the independent predictors of noninvasive ventilation outcomes in AECOPD patients were identified by multivariate logistic regression analysis.RESULTS There were no significant differences in gender,age,body mass index,complications,systolic pressure,heart rate,mean arterial pressure,respiratory rate,oxygen saturation,partial pressure of oxygen,oxygenation index,or time of inspiration between patients with successful and failed mechanical ventilation(P>0.05).The patients with successful noninvasive ventilation had shorter hospital stays and lower partial pressure of carbon dioxide(PaCO_(2))than those with failed treatment,while potential of hydrogen(pH),diaphragm thickening fraction(DTF),diaphragm activity,and diaphragm movement time were significantly higher than those with failed treatment(P<0.05).pH[odds ratio(OR)=0.005,P<0.05],PaCO_(2)(OR=0.430,P<0.05),and DTF(OR=0.570,P<0.05)were identified to be independent factors influencing the outcome of mechanical ventilation in AECOPD patients.CONCLUSION The DUS index DTF can better predict the outcome of non-invasive ventilation in AECOPD patients.

Effects of C2 hemisection on respiratory and cardiovascular functions in rats

High ce rvical spinal co rd injuries induce permanent neuromotor and autonomic deficits.These injuries impact both central respiratory and cardiovascular functions through modulation of the sympathetic nervous system.So far,cardiovascular studies have focused on models of complete contusion or transection at the lower cervical and thoracic levels and diaphragm activity evaluations using invasive methods.The present study aimed to evaluate the impact of C2 hemisection on different parameters representing vital functions(i.e.,respiratory function,cardiovascular,and renal filtration parameters)at the moment of injury and 7 days post-injury in rats.No ventilatory parameters evaluated by plethys mography were impacted during quiet breathing after 7 days post-injury,whereas permanent diaphragm hemiplegia was observed by ultrasound and confirmed by diaphragmatic electromyography in anesthetized rats.Interestingly,the mean arterial pressure was reduced immediately after C2 hemisection,with complete compensation at 7 days post-injury.Renal filtration was unaffected at 7 days post-injury;however,remnant systolic dysfunction chara cterized by a reduced left ventricular ejection fraction persisted at 7 days post-injury.Taken together,these results demonstrated that following C2 hemisection,diaphragm activity and systolic function are impa cted up to 7 days post-injury,whereas the respiratory and cardiovascular systems display vast ada ptation to maintain ventilatory parameters and blood pressure homeostasis,with the latter likely sustained by the remaining descending sympathetic inputs spared by the initial injury.A better broad characterization of the physiopathology of high cervical spinal cord injuries covering a longer time period post-injury could be beneficial for understanding evaluations of putative therapeutics to further increase cardiorespiratory recovery.

Effects of Propofol on Respiratory Drive and Patient-ventilator Synchrony during Pressure Support Ventilation in Postoperative Patients： A Prospective Study

Background： Propofol is increasingly nsed during partial support mechanical ventilation such as pressure support ventilation （PSV） in postoperative patients. However breathing pattern, respiratory drive, and patient-ventilator synchrony are affected by the sedative used and the sedation depth. The present study aimed to evaluate the physiologic effects of varying depths ofpropofbl sedation oll respiratory drive and patient-ventilator synchrony during PSV in postoperative patients. Methods： Eight postoperative patients receiving PSV for 〈24 h were enrolled. Propofol was administered to achieve and maintain a Ramsay score of 4, and the inspiratory pressure support was titrated to obtain a tidal volume （VT） of 6-8 ml/kg. Then, tile propolbl dose was reduced to achieve and maintain a Ramsay score of 3 and then 2. At each Ramsay level, the patient underwent 30-rain trials of PSV. We measured the electrical activity of the diaphragm, flow, airway presstlre, neuro-ventilatory efficiency （NVE）, and patient-ventilator synchrony. Results： Increasing the depth of sedation reduced the peak and mean electrical activity of the diaphragm, which suggested a decrease in respiratory drive, while VT remained unchanged. The NVE increased with an increase in the depth of sedation. Minute ventilation and inspiratory duty cycle decreased with an increase in the depth of sedation, but this only achieved statistical significance between Ramsay 2 and both Ramsay 4 and 3 （P 〈 0.05）. The ineffective triggering index increased with increasing sedation depth （9.5 -4- 4.0%, 6.7 - 2.0%, and 4.2-2.1% for Ramsay 4, 3, and 2, respectively） and achieved statistical significance between each pair of depth of sedation （P 〈 0.05）. The depth of sedation did not affect gas exchange. Conclusions： Propofol inhibits respiratory drive and deteriorates patient-ventilator synchrony to tile extent that varies with tile depth of sedation. Propolbl has less effect on breathing pattern and has no effect on VT and gas exchange in postoperative patients with PSV.