The forgotten Korotkoff phases: How often are phases II and III present, and how do they relate to the other Korotkoff phases?

Abstract Background: There are no data on the pattern of the Korotkoff phases in the normal population. This study was designed to describe the pattern of Korotkoff phase distribution in adults and children; to measure the duration of each of the phases; and to describe the differences between adults and children. Methods: A total of 57 children (7 to 8 years old) and 59 adults (median age 47 years, range 30 to 62 years) were studied. The pressure in the arm cuff was deflated using a device to provide a consistent deflation rate. The Korotkoff sounds were recorded to MiniDisc from the bell of a stethoscope and each sound described as phase I, II, III, or IV. Results: The most common pattern of Korotkoff phase distribution was for all five phases to be present (children [23/57; 40%], adults [24/59; 41%]). Phases I and IV were more common in children than in adults (56/57 [98%] v 47/59 [80%]; P = .002 for phase I; 52/57 [91%] v 44/59 [75%]; P = .018 for phase IV). Phases II and III were less common in children than in adults (32/57 [56%] v 50/59 [85%], P = .001 for phase II; 27/57 [47%] v 45/59 [76%], P = .001 for phase III). Phases I and IV were longer in children (median 3.9 [interquartile range, IQR 2.1 to 6.7] and 6.7 [IQR 3.2 to 9.8] sec, respectively) compared with adults (1.3 [IQR 0.7 to 2.7] and 1.7 [IQR 0.3 to 2.6), P< .001). Conclusions: There are clear differences in the Korotkoff phases between adults and children. The length of phases II and III increase with age with concomitant decrease in phases I and IV. These differences between adults and children remain unexplained.