Phenylephrine and phentolamine
This patient was aged 55 years, weighed 58 kg and was undergoing coronary artery bypass grafting. Phenylephrine (0.5 mg) was given 15 s before the blood pressure starts to rise. This blood pressure rise is due to an increase in SVR which in turn causes a small fall in stroke volume, heart rate and cardiac output. SVR then falls rapidly until the phenylephrine recirculates and causes a more prolonged rise in SVR. Phentolamine (1.5 mg) was then given to reduce the blood pressure prior to aortic cannulation. This caused a fall in SVR accompanied by an increase in stroke volume, heart rate and therefore cardiac output. The systolic pressure variation (SPV) is also more obvious towards the end of the trace. Resulta from 5 patients after injection of phenylephrine are here.