Impedance cardiography: noninvasive measurement of hemodynamics and thoracic fluid content during endoscopic thoracic sympathectomy.

Endoscopic thoracic sympathectomy (ETS) is a minimally invasive procedure for treating palmar hyperhidrosis (PH). Hemodynamic changes are associated with CO(2) insufflation during ETS. In the present study, we examined hemodynamic changes during general anesthesia using impedance cardiography (ICG) monitor. Seventeen adult patients (15 males) scheduled to undergo elective unilateral ETS for treatment of PH were enrolled in the study. Patients with cardiorespiratory diseases were excluded from the study. Their age and weight mean values were 26.5 +/- 5 years, 71.9 +/- 11.5 kg, respectively. Besides routine monitoring, impedance cardiography monitor was used to measure cardiac output (CO), cardiac index (CI), stroke volume (SV), thoracic fluid content (TFC), and systemic vascular resistance (SVR). Three phases were defined for data collection: A, prior to CO(2) insufflation; B during gas insufflation (at 10, 5, and 2 mm Hg intrathoracic pressures); and C, after gas deflation. Repeated-measures analysis of variance (ANOVA) was used for statistical analysis and post hoc Bonferroni test for multiple comparisons of the data obtained. For all comparisons, P < 0.05 was considered significant. Systemic vascular resistance significantly increased at stages B10 and 5 compared with stage A mean value (P < 0.05). CO, CI, and SV mean values decreased significantly at stage B compared with stage A mean values. The mean values of thoracic fluid content at stages A, B10, 5, 2, and C were 33 +/- 5, 30.6 +/- 3.5, 31 +/- 3.4, 31.6 +/- 3.3, and 32.5 +/- 6.8/kOmega, respectively with significant differences (P < 0.05). Significant reductions of cardiac parameters were reported in the present study, but they were of minimal clinical significance. Of interest was the significant reduction of thoracic fluid content during CO(2) insufflation, whether it correlates to the magnitude of compression, caused by CO(2) insufflation accompanied by high systemic vascular resistance or sympathectomy procedure, yet to be further studied.