TY - JOUR
T1 - Monitoring adequacy of α-adrenoceptor blockade following systemic phentolamine administration
AU - Raja, Srinivasa N.
AU - Turnquist, Jennifer L.
AU - Meleka, Sherif
AU - Campbell, James N.
N1 - Funding Information:
This work was supported by NIH grant NS-26363. We thank Tim Hartke for technical assistance.
PY - 1996/1
Y1 - 1996/1
N2 - Systemic phentolamine administration has been suggested as a diagnostic tool for identifying patients with sympathetically maintained pain (SMP) (Raja et al. 1991). The dose of phentolamine to produce adequate blockade of peripheral α-adrenoceptor function has, however, not been previously determined. In this study, the effects of two different doses of phentolamine on peripheral sympathetic vasoconstrictor function were investigated. One-hundred and seventeen (117) patients with chronic extremity pain underwent 130 phentolamine diagnostic tests using two different doses of phentolamine (0.5 mg/kg over 20 min (n = 60) and 1 mg/kg-over 10 min (n = 59)). Eleven (11) patients did not receive phentolamine during the test. Cutaneous temperature was measured in the distal extremity before and after administration of phentolamine. In a subset of patients, baseline blood flow and sympathetically mediated vasoconstrictor response (SMR) to deep inhalation were measured on glabrous skin using laser Doppler flowmetry. SMR was elicited with a 5-sec maximal inspiratory gasp. A dose-related increase in cutaneous temperature was observed. In addition, baseline blood flow increased and SMR was attenuated after both doses of phentolamine, but to a greater degree after the 1 mg/kg dose. However, SMR was not completely attenuated, even after administration of the higher phentolamine dose. These results indicate that a phentolamine dose of 1 mg/kg over 10 min more completely blocks α-adrenoceptor function than a dose of 0.5 mg/kg over 20 min. We therefore recommend that to ensure adequate α-adrenoceptor blockade the higher phentolamine dose be used in the phentolamine diagnostic test for SMP.
AB - Systemic phentolamine administration has been suggested as a diagnostic tool for identifying patients with sympathetically maintained pain (SMP) (Raja et al. 1991). The dose of phentolamine to produce adequate blockade of peripheral α-adrenoceptor function has, however, not been previously determined. In this study, the effects of two different doses of phentolamine on peripheral sympathetic vasoconstrictor function were investigated. One-hundred and seventeen (117) patients with chronic extremity pain underwent 130 phentolamine diagnostic tests using two different doses of phentolamine (0.5 mg/kg over 20 min (n = 60) and 1 mg/kg-over 10 min (n = 59)). Eleven (11) patients did not receive phentolamine during the test. Cutaneous temperature was measured in the distal extremity before and after administration of phentolamine. In a subset of patients, baseline blood flow and sympathetically mediated vasoconstrictor response (SMR) to deep inhalation were measured on glabrous skin using laser Doppler flowmetry. SMR was elicited with a 5-sec maximal inspiratory gasp. A dose-related increase in cutaneous temperature was observed. In addition, baseline blood flow increased and SMR was attenuated after both doses of phentolamine, but to a greater degree after the 1 mg/kg dose. However, SMR was not completely attenuated, even after administration of the higher phentolamine dose. These results indicate that a phentolamine dose of 1 mg/kg over 10 min more completely blocks α-adrenoceptor function than a dose of 0.5 mg/kg over 20 min. We therefore recommend that to ensure adequate α-adrenoceptor blockade the higher phentolamine dose be used in the phentolamine diagnostic test for SMP.
KW - Laser Doppler
KW - Phentolamine
KW - Reflex sympathetic dystrophy
KW - Sympathetic nervous system
KW - Sympathetically maintained pain
KW - α-Adrenoceptor blocker
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U2 - 10.1016/0304-3959(95)00099-2
DO - 10.1016/0304-3959(95)00099-2
M3 - Article
C2 - 8867263
AN - SCOPUS:0029671402
SN - 0304-3959
VL - 64
SP - 197
EP - 204
JO - Pain
JF - Pain
IS - 1
ER -