Journal of applied physiology
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Although mechanical ventilation (MV) is a life-saving intervention, prolonged MV can lead to deleterious effects on diaphragm function, including vascular incompetence and weaning failure. During MV, positive end-expiratory pressure (PEEP) is used to maintain small airway patency and mitigate alveolar damage. We tested the hypothesis that increased intrathoracic pressure with high levels of PEEP would increase diaphragm vascular resistance and decrease perfusion. ⋯ These reductions in blood flow to the quiescent diaphragm during MV could predispose critically ill patients to weaning complications. NEW & NOTEWORTHY This is the first study, to our knowledge, demonstrating that mechanical ventilation, with low and high positive-end expiratory pressure (PEEP), increases vascular resistance and reduces total and regional diaphragm perfusion. The rapid reduction in diaphragm perfusion and increased vascular resistance may initiate a cascade of events that predispose the diaphragm to vascular and thus contractile dysfunction with prolonged mechanical ventilation.
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Reported incidence of postoperative opioid-induced respiratory depression (OIRD) ranges from 0.5-41% and is not reliably predicted by traditional risk factors. This study tests a new methodology to investigate ventilatory chemosensitivity as a new potential risk factor and explore OIRD distribution across sleep and wakefulness. Preoperative patient ventilatory chemosensitivity was quantified by hypercapnic ventilatory responses with (HCVRREMI, effect site concentration 0.7 or 2.0 ng/mL) and without (HCVRBL) remifentanil during hyperoxia and hypoxia. ⋯ NEW & NOTEWORTHY Our new and noteworthy methodology allows for exploration of preoperative ventilatory chemosensitivity, measured as the hypercapnic ventilatory response (HCVR), as a risk factor for postoperative opioid-induced respiratory depression (OIRD). This feasible and reliable methodology produced preliminary data that showed highly variable depression of HCVR by remifentanil, predominance of OIRD during light sleep, and potentially negative correlation between OIRD frequency generally and HCVR measurements when measured in the presence of remifentanil. Although the results are preliminary in nature, this novel methodology may guide future studies that can one day lead to effective clinical screening tools.
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Randomized Controlled Trial
Sixteen weeks of testosterone with or without evoked resistance training on protein expression, fiber hypertrophy and mitochondrial health after spinal cord injury.
We investigated the effects of testosterone replacement therapy (TRT) with and without evoked resistance training (RT) on protein expression of key metabolic and hypertrophy regulators, muscle fiber cross-sectional area (CSA), and markers of mitochondrial health after spinal cord injury (SCI). Twenty-two men with chronic motor complete SCI were randomly assigned to either TRT + RT (n = 11) or TRT (n = 11) for 16 wk. TRT + RT men underwent twice weekly progressive RT using electrical stimulation with ankle weights. ⋯ NEW & NOTEWORTHY Fiber cross-sectional area (CSA), protein expression, mitochondrial citrate synthase (CS), and succinate dehydrogenase (SDH) were measured following 16 wk of low-dose testosterone replacement therapy (TRT) with and without electrically evoked resistance training (RT) in men with spinal cord injury (SCI). Fiber CSA and protein expression of total GLUT4, total Akt, and phosphorylated Akt increased following TRT + RT but not in the TRT-only group. Mitochondrial CS and SDH increased after TRT + RT but not in TRT-only group.
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In recent months, the coronavirus disease 2019 (COVID-19) pandemic has sent many countries into crisis. Studies have shown that this virus causes worse outcomes and a higher mortality in men than in women. ⋯ Angiotensin-converting enzyme 2 (ACE2) acts as the receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes COVID-19. The expression of ACE2 is influenced by sex hormones; therefore, we discuss in this article that this could be one of the reasons why COVID-19 is more prevalent in men than in women.