Alteration in diaphragmatic function induced by acute necrotizing pancreatitis in a rodent model

Some of the common complications of acute necrotizing pancreatitis also inv olve pulmonary complications. These manifestations are often associated wit h a cephalad diaphragmatic shift. We hypothized that diaphragmatic function might be directly compromised by the acute abdominal process. This hypothe sis was tested on an acute necrotizing pancreatitis (ANP) rat model. We ass essed the diaphragm and peripheral (Extensor Digitorum Longus and Soleus) m uscle properties in vitro using strips in control (C) and ANP animals. Cont ractile parameters included single twitch and a force-frequency curve (10 t o 100 Hz), and an endurance capacity index (T50%) was calculated after a re petitive stimulation (30 Hz). Breathing pattern was not different between c ontrol and ANP animals, and muscular histologic examination was normal. How ever, ANP was associated with a marked decrease in diaphragmatic strength f or all frequencies of stimulation when compared with C. Endurance capacity was also reduced in ANP animals as assessed by a lower T50% (ANP: 31 +/- 10 .5 s; C: 49 +/- 10.3 s; p < 0.05). By contrast, no significant change in pe ripheral muscle function was observed in both groups. We conclude that ANP causes impairment in diaphragmatic strength and endurance capacity, whereas peripheral muscles are spared. These findings suggest that alterations in the respiratory pump may be involved in the genesis of acute respiratory fa ilure in ANP.