Sr. Steinhauer et al., Respiratory sinus arrhythmia in persons with organic solvent exposure: Comparisons with anxiety patients and controls, ARCH ENV HE, 56(2), 2001, pp. 175-180
Persons exposed to organic solvents have psychiatric symptomatology and cog
nitive impairments. The results of several studies have suggested that some
psychiatric symptoms in these patients reflect similar reactions observed
in patients with anxiety disorders. Respiratory sinus arrhythmia provides a
n indication of impaired autonomic functioning. Whereas decreased respirato
ry sinus arrhythmia has been reported in anxiety patients, investigators ha
ve also noted that higher respiratory rates in these patients obscure diffe
rentiation of respiratory sinus arrhythmia from normal values. In this stud
y the authors recorded multiple parameters of respiratory sinus arrhythmia
under a paced-breathing condition in 28 patients with solvent exposure, in
18 patients with anxiety disorder, and in 31 controls. The authors observed
a high 1-y retest reliability for a subset of the subjects. Significantly
reduced respiratory sinus arrhythmia was observed in both anxiety and solve
nt-exposed patients, compared with controls. Maximum mean heart rates/cycle
did not differ among groups, but minimum heart rates were significantly lo
wer for controls than for the two patient groups. The findings suggested th
at reduced respiratory sinus arrhythmia among patients is not related to hi
gher maximum rates but, rather, to a decrease in vagally mediated alteratio
n associated with respiratory changes observed in both patient groups.