RESUMO
Ketamine is used to supplement sedation during cardiac catheterization. We studied ketamine-induced circulatory changes in 28 acyanotic children (18 of whom had left-to-right shunts), aged 4-161 months (mean, 33 months). Oxygen consumption (VO2) was measured continuously. In the 18 patients with shunts, the pulmonary to systemic flow ratio fell slightly (2.3 +/- 1.1 to 1.8 +/- 0.4, p less than 0.05). In all patients, the ratio of pulmonary (PVR) to systemic vascular resistance (SVR) rose from 0.16 +/- 0.09 to 0.28 +/- 0.21, p less than 0.001. Ketamine increases VO2, heart rate, cardiac output, and pulmonary arterial pressure (PAP). The rise in PAP is more consistent than the rise in PVR; resistance changes were greatest in patients with elevated resting PVR (r = 0.54). Caution should be used in administering ketamine to selected subjects; moreover, ketamine can confuse interpretation of cardiac catheterization data, especially if VO2 is assumed and not measured.