The hemodynamic responses to an intravenous test dose in vascular surgical patients

The study was designed to investigate the hemodynamic responses to intravenous (IV) injections of various epidural test doses in vascular surgical patients to determine whether previously established criteria in healthier populations were valid in this inherently sicker population. A double-blind, prospective randomized study was performed on 50 patients, not receiving beta-adrenergic antagonists, presenting for vascular surgery and requiring an arterial line. Patients were randomly assigned to receive a 3-mL injection of one of five solutions, either saline (Group 1), lidocaine 45 mg (Group 2), lidocaine 45 mg and epinephrine 5 micrograms (Group 3), lidocaine 45 mg and epinephrine 10 micrograms (Group 4), or lidocaine 45 mg and epinephrine 15 micrograms (Group 5). After injection, a blinded observer recorded arterial blood pressure and heart rate (HR) every 15 s for 3 min. The changes in HR, systolic (SBP), mean (MBP), and diastolic (DBP) blood pressure as well as time to maximum change were analyzed both within and between groups. Only Group 5 had significant within-group changes for all hemodynamic variables measured. Only in the comparison between Groups 1 and 5 and between Groups 2 and 5 were there significant changes in both HR and SBP. The mean increase in HR and SBP within Group 5 was 17.0 +/- 5.9 bpm and 31.0 +/- 10.5 mm Hg, respectively. No differences were found between groups for time to maximum change for HR and SBP which for Group 5 were 64.5 +/- 37.4 s and 90.0 +/- 56.7 s, respectively. To achieve 100% sensitivity and specificity for HR increase, the criterion established was > or = 9 bpm.(ABSTRACT TRUNCATED AT 250 WORDS)