Reaction to indigo carmine.

The commonly encountered cardiovascular effects of intravenous indigo carmine administration is transient alpha-receptor stimulation, namely increased total peripheral resistance, diastolic and systolic blood pressure, and central venous pressure with decreased cardiac output, stroke volume and heart rate. These usually cause no problems and frequently go undetected unless the patient is monitored closely during that brief interval. However, significant problems occur occasionally and its use is not totally without risks.