Muscle & nerve
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Doxorubicin is a chemotherapeutic agent prescribed for a variety of tumors. While undergoing treatment, patients exhibit frequent symptoms that suggest respiratory muscle weakness. Cancer patients can receive doxorubicin chemotherapy through either intravenous (IV) or intraperitoneal (IP) injections. ⋯ Doxorubicin consistently depressed diaphragm force with both methods of administration (P < 0.01). Doxorubicin IP exaggerated the depression in diaphragm force and stimulated tissue inflammation and muscle fiber injury. These results suggest that clinically relevant doses of doxorubicin cause respiratory muscle weakness and that the loss of function depends, in part, on the route of administration.
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Information on the interactive effects of methylprednisolone, controlled mechanical ventilation (CMV), and assisted mechanical ventilation (AMV) on diaphragm function is sparse. Sedated rabbits received 2 days of CMV, AMV, and spontaneous breathing (SB), with either methylprednisolone (MP; 60 mg/kg/day intravenously) or saline. There was also a control group. ⋯ Short-term, high-dose MP had no additive effects on CMV-induced diaphragm dysfunction. Combined MP plus AMV impaired diaphragm function, but AMV alone did not. We found that acute, high-dose MP produces diaphragm dysfunction depending on the mode of mechanical ventilation.
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We present two cases with and without a latency difference of the compound muscle action potential (CMAP) from the abductor digiti minimi (ADM) and the first dorsal interosseous (FDI). In each case, onset latencies of FDI CMAPs using the contralateral small finger as E2 were shorter than those of belly-tendon CMAPs from the ADM and FDI. We conclude that onset of the belly-tendon FDI CMAP does not necessarily indicate initial activation of the FDI.