Auscultatory gap

An auscultatory gap is a period of diminished or absent Korotkoff sounds during the manual measurement of blood pressure. The improper interpretation of this gap may lead to blood pressure monitoring errors: namely, an underestimation of systolic blood pressure and/or an overestimation of diastolic blood pressure. In order to correct for an auscultatory gap the radial pulse should be monitored by palpation. It is therefore recommended to palpate and auscultate when manually recording a patient's blood pressure. Typically the blood pressure obtained via palpation is around 10 mmHg lower than the pressure obtained via auscultation. In general, the examiner can avoid being confused by an auscultatory gap by always inflating a blood pressure cuff to 20-40 mmHg higher than the pressure required to occlude the brachial pulse.