Serum substance P concentrations and silent aspiration in elderly patients with stroke

Abstract

Substance P (SP) is released from sensory nerve terminals and degraded by angiotensin-converting enzyme (ACE),1 and its action is potentiated by ACE inhibitors.2 SP levels in the sputum are reportedly low in patients with aspiration pneumonia,3 and silent aspiration disappears by treatment with ACE inhibitors in association with an increase in serum concentrations of SP in hypertensive patients with stroke.4 However, the relation between serum SP concentrations and improvement in silent aspiration has not been investigated yet in elderly patients with stroke. Therefore, we administered various doses of an ACE inhibitor to elderly patients with stroke to determine the effective concentration of serum SP that correlates best with improvement of the silent aspiration in such patients. The eligible patients had a history of stroke but were not bedridden. We enrolled 60 patients (29 men and 31 women) with normotension and silent aspiration detected by the method described below. Randomization was done by a random-numbers table, and the list …