Fig. 3. A typical alternans pattern associated with hypercapnia (ET^CO2= 60 mmHg) in the presence of 1.6% end-tidal halothane concentration. Parallel electrocardiogram, plethysmogram, and capnogram tracing 10 min after induction of anesthesia in a 39-yr-old man approximately 130 s after development of pulsus alternans. The blood pressure shown here was recorded at the very beginning of PA. This patient developed sinus tachycardia, tachypnea, systolic hypertension (165 mmHg) followed by blood pressure reduction (90/55 mmHg), and minimal desaturation (oxygen saturation 94%, fraction of inspired oxygen = 1) 3 min after PA occurrence.