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The reproducibility of Korotkoff 4 and 5
.4JI-J-AKXIST 19%.VOL.
9, NO. 8
The Reproducibility
of .KorotkoK 4 and 5
Hammond et al’ recoxmnend the use of Korelkoff phase 4 (K4) rather than phase 5 (K5j to define the diastolic endpoint ir, children. The evidence presented to support the use of K4 appears to be the increased incidence of absent K5 in younger children. Howerver Shari et al found, in a smrvey of 3012 subjects aged from 5 to 24, that KS was consistently absent (on three measureme&) in only 0.6% as compared to 3.2% for K4.* The use of K4 in pregnancy is also recommended by many authorities because of a similar reported absence of K5 in a significant minority of women? We have recently
published a study comparing the interobsemer identification and reproducibility of Korotkoff sounds in 250 pregnant women (1240 measurements). In tltis study measurements were taken by blinded paired observers taking simultaneous measurements using dual stethoscope and manometem4 Korotkoff 5 was always identified and never approached zero. Furthermore, K4 could be heard in only 52% of the measurements, but more importantly, observers could only agree to its detection in 19% of readings. This means that in 33Y0of a!1 measurements K4 was only heard by one of the two observers taking a simultaneous measurement. Similar findings were found in nonpregnant controls. For each individual women the identification of K4 was highly inconsistent. While an important arbiter of choice between K4 and IS5 would be the relationship of each to oi;tcome, it is more important to ensure that K4 and K5 are reproducible between observers during simultaneous auscultation before either can be recommended for use. If KS is absent, then the measurement should be repeated, and only on the very rare occasions that it is consis-
tently absent should K4 h noted. It is possi?& that excess pressure on the head of the stethoscope can lead to turbulent flow and cause sounds to be present at zero cuff pressure (absent KS) .* The selection of K5 as the diastolic endpoint for all populations would reduce confusion among healtlt care workers, and allow comparison between epidemiological studies and across the age range. Hammond et ai state that K4 is more reproducible below the age of 13 years. In view of our findings, we now believe the use
of K4 should be abandoned, unless the simultaneous interobserver reproducibi!ity of TiC4 is better than that of K5 in childhood. REFERENCES IIamnond IW, Urbina EM, Wattigney WA, et al: Comparison of fourth and fifth Korutkoff diastolic blood pressures in 5 to 30 year old individu&. Am J Hgpeztens 1996;8:1053--1089. Uhari M, Nuutinen M; Turtinen J, Pokka T: Pulse sounds and measurement of diastolic blood pressure in chilidren. Lancet 1991;338:159-161. Davev DA. MacGillivrav I: The classification ancl definiti& of t$e hyperten&e disorders of pregnancy. Am J Ohstet Gynecol1988;158:592-898. Sherman AH, Gupta M, Hallignn A, et al: Lack of reproducibility in pregnancy of Xorotkoff phase IV as measured by mercury sphygmomanometry. Lancet 19%; 347:139-142. JAMES PENPC, ANDREW SHENNAN, AND MICHAELDE SWET Received March 18, 1996. Accepted March 29, 1996. From the Institute of OSetetdcs and Gynaecology, Queen Charlotte’s Hospitai, London 1% OXG, England.
9, NO. 8
The Reproducibility
of .KorotkoK 4 and 5
Hammond et al’ recoxmnend the use of Korelkoff phase 4 (K4) rather than phase 5 (K5j to define the diastolic endpoint ir, children. The evidence presented to support the use of K4 appears to be the increased incidence of absent K5 in younger children. Howerver Shari et al found, in a smrvey of 3012 subjects aged from 5 to 24, that KS was consistently absent (on three measureme&) in only 0.6% as compared to 3.2% for K4.* The use of K4 in pregnancy is also recommended by many authorities because of a similar reported absence of K5 in a significant minority of women? We have recently
published a study comparing the interobsemer identification and reproducibility of Korotkoff sounds in 250 pregnant women (1240 measurements). In tltis study measurements were taken by blinded paired observers taking simultaneous measurements using dual stethoscope and manometem4 Korotkoff 5 was always identified and never approached zero. Furthermore, K4 could be heard in only 52% of the measurements, but more importantly, observers could only agree to its detection in 19% of readings. This means that in 33Y0of a!1 measurements K4 was only heard by one of the two observers taking a simultaneous measurement. Similar findings were found in nonpregnant controls. For each individual women the identification of K4 was highly inconsistent. While an important arbiter of choice between K4 and IS5 would be the relationship of each to oi;tcome, it is more important to ensure that K4 and K5 are reproducible between observers during simultaneous auscultation before either can be recommended for use. If KS is absent, then the measurement should be repeated, and only on the very rare occasions that it is consis-
tently absent should K4 h noted. It is possi?& that excess pressure on the head of the stethoscope can lead to turbulent flow and cause sounds to be present at zero cuff pressure (absent KS) .* The selection of K5 as the diastolic endpoint for all populations would reduce confusion among healtlt care workers, and allow comparison between epidemiological studies and across the age range. Hammond et ai state that K4 is more reproducible below the age of 13 years. In view of our findings, we now believe the use
of K4 should be abandoned, unless the simultaneous interobserver reproducibi!ity of TiC4 is better than that of K5 in childhood. REFERENCES IIamnond IW, Urbina EM, Wattigney WA, et al: Comparison of fourth and fifth Korutkoff diastolic blood pressures in 5 to 30 year old individu&. Am J Hgpeztens 1996;8:1053--1089. Uhari M, Nuutinen M; Turtinen J, Pokka T: Pulse sounds and measurement of diastolic blood pressure in chilidren. Lancet 1991;338:159-161. Davev DA. MacGillivrav I: The classification ancl definiti& of t$e hyperten&e disorders of pregnancy. Am J Ohstet Gynecol1988;158:592-898. Sherman AH, Gupta M, Hallignn A, et al: Lack of reproducibility in pregnancy of Xorotkoff phase IV as measured by mercury sphygmomanometry. Lancet 19%; 347:139-142. JAMES PENPC, ANDREW SHENNAN, AND MICHAELDE SWET Received March 18, 1996. Accepted March 29, 1996. From the Institute of OSetetdcs and Gynaecology, Queen Charlotte’s Hospitai, London 1% OXG, England.