Korotkoff sounds in neonates, infants, and toddlers.

Korotkoff sounds (KSs) are the clinical norm for noninvasively estimating systemic arterial blood pressure (BP) in children and adults. Their existence and reliability in children <3 years old was unknown. This study addressed the presence and accuracy of KSs in children <3 years. Measurements of the first KS (K1), K4, and K5 (the commonly used sounds) were compared with invasive measurements of systolic and diastolic BP in > or =3 inflations/subject. Subjects were prospectively divided by age <1 (n = 20), 1 to 12 (n = 29), and 13 to 36 months (n = 17). KSs were audible with low frequency in subjects <1 month old and they were excluded from further analysis. In 143 inflations, K1 was audible in 125, K4 in 104, and K5 in 114; the frequency of audible KSs increased with subject age. Reliability of KSs as a surrogate for measured systolic and diastolic BP was assessed using paired t tests. K1 was not significantly different for the entire group or any subgroup. K4 was significantly different in all age groups. K5 was significantly different in only subjects <6 months. In conclusion, K1, K4, and K5 are routinely audible and K1 and K5 provide a reliable estimate of systolic and diastolic BP in children age 1 to 36 months.