In Reply:—

We thank Introna et al.  1for their kind comments regarding our manuscript. 2The authors correctly point out that a comprehensive approach to assessing the autonomic nervous system effects of anesthetic and sedative drugs provides clinically useful insight into their cardiovascular effects. Measurement of variations in systolic blood pressure is a well-characterized method for measuring peripheral sympathetic nervous system responses to various autonomic stressors, and such data might have furthered our findings. 2,3We chose, however, to focus on the cardiac autonomic effects of sedative doses of dexmedetomidine during clinically common thermal stress. Future investigation along these lines that incorporate measurement of systolic blood pressure variations might prove to be useful.

1.
Introna R, Blair J, Martin DC: Measurement of the LF component of blood pressure variability can assist the interpretation of HRV data. A nesthesiology 2002; 97: 592–8
2.
Hogue CW Jr, Talke P, Stein PK, Richardson C, Domitrovich PP, Sessler DI: Autonomic nervous system responses during sedative infusions of dexmedetomidine. A nesthesiology 2002; 97: 592–8
3.
Pagani M, Lombardi F, Guzzetti S, Rimoldi G, Furlan R, Pizzinelli P, Sandrone G, Malfatto G, Dell'Orto S, Piccalugga E, Turiel M, Baselli G, Ceruttti S, Malliani A: Power spectral analysis of heart rate and arterial pressure variabilities as a marker of sympatho-vagal interaction in man and conscious dog. Circ Res 1986; 59: 178–193