Can a clinically useful aortic pressure wave be derived from a radial pressure wave?
BACKGROUND
The information contained in arterial pressure waveforms is probably underused by most clinicians who manage critically ill patients. It is not generally known that an aortic pressure wave can be synthesized by applying a generalized transfer function to the radial arterial pressure wave. We validated a commercially available system, SphygmoCo (PWV Medical, Sydney).


METHODS
Ascending aortic pressure waves were synthesized and comparisons were made between the synthesized aortic waveforms, the measured aortic and radial arterial waveforms. Ascending aortic pressure waves (catheter-tip manometer) and radial artery pressure waves (short fluid-filled catheter) were recorded simultaneously in 12 patients with angina pectoris (age 62-76 years) undergoing cardiac catheterization. Patients were studied at rest, following midazolam, sublingual nitroglycerin and during Valsalva manoeuvres.


RESULTS
Both midazolam and nitroglycerin lowered mean arterial pressure but nitroglycerin caused a more selective decrease in the measured and synthesized aortic systolic pressures than in the radial artery pressure. The synthesized aortic systolic pressure was less, by 6-8 mm Hg (SD 2-3) and the synthesized aortic diastolic pressure greater, by 4 mm Hg (SD 2). Despite these differences in pulse pressure, the synthesized waveform tracked the measured waveform before and during interventions.


CONCLUSIONS
By deriving an aortic waveform from the radial pulse, monitoring of left ventricular afterload can improve without more invasive means.
Söderström
S
S
Department of Anaesthesia and Intensive Care, Sahlgrenska University Hospital, Göteborg, Sweden.
Nyberg
G
G
O'Rourke
M F
MF
Sellgren
J
J
Pontén
J
J
D000787:Angina Pectoris / Q000503:physiopathology*; D014151:Anti-Anxiety Agents / Q000494:pharmacology; D001011:Aorta / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D001795:Blood Pressure Determination / Q000379:methods; D006328:Cardiac Catheterization; D004562:Electrocardiography; D005260:Female; D006801:Humans; D008297:Male; D008874:Midazolam / Q000494:pharmacology; D008991:Monitoring, Physiologic / Q000379:methods; D005996:Nitroglycerin / Q000494:pharmacology; D017534:Radial Artery / Q000502:physiology*; D015203:Reproducibility of Results; D012815:Signal Processing, Computer-Assisted; D014636:Valsalva Maneuver; D014665:Vasodilator Agents / Q000494:pharmacology
D014151:Anti-Anxiety Agents; D014665:Vasodilator Agents; D005996:Nitroglycerin; D008874:Midazolam