William Elder Hammer

Indirect measurement of arterial blood pressure with the aid of a digital computer

Abstract Indirect measurement of arterial pressure was carried out using a cuff and a microphone positioned over the brachial artery. Selective sound sampling, data analysis, and remote control of the arm cuff pressure were used. Criteria for “acceptability” of Korotkoff sounds were developed. Sampling of the microphone signal was done at cuff pressures where an acceptable sound was expected. Data obtained in 15 postoperative cardiac patients with this method and with a direct method were compared. Indirect systolic measurements averaged 11 mm. Hg lower than direct measurements. Diastolic averages for direct and indirect pressures were equal.