Accurate Blood Pressure Measurement in Children

Abstract

Accurate blood pressure determination is crucial in the management of critically ill infants and children, in detecting secondary hypertension amenable to surgical correction, and in the early detection of essential hypertension. However, the pediatric literature consists of contradictory methodology and extreme variations in the ‘limits of normal’. An indirect blood pressure measuring device requires validation against a direct arterial pressure. Although intra-arterial pressure is accepted as the reference standard, careful attention to technique is required: relatively short, stiff tubing, without compliant elements, and the elimination of blood clots and even microscopic air bubbles. An arterial line in an extremity, particularly the foot, will register a higher pressure than is present in the aorta due to systolic amplification, especially in patients who are vasoconstricted. Indirect blood pressure measurements by any of several methods is affected by multiple variables. This is reflected in conflicting recommendations for the upper limit of normal for systolic blood pressure that vary as much as 30 mm Hg. Selection of blood pressure cuff size is the major source of this variance. The laws of physics, supported by careful intra-arterial measurements, indicate that the correct cuff size is based on the diameter (or circumference) of the limb, not the length. Using the length may produce adequate readings if the subject is of normal weight/height relationship, but will result in hypertensive readings in obese subjects who are actually normotensive and in mildly low readings for thin subjects. The correct cuff width is 125-155 % of the diameter of the limb, whether arm or leg, or 40-50% of the circumference. We offer a working guide to normal blood pressure values derived from data collected with appropriate-sized cuffs with minor extrapolations.

Hemodynamic Disturbances in Premature Infants Born after Chorioamnionitis: Association with Cord Blood Cytokine Concentrations

“…Gestational age assessment was based on either a first trimester ultrasound or the last menstrual period if no early ultrasound was available. Exclusion criteria included congenital anomalies of the brain, heart, or kidneys; intrauterine growth restriction [estimated fetal weight below the third percentile for gestational age, no growth on three serial prenatal ultrasounds, or birth weight Ͻ2 SD below the mean (26)]; in utero demise of a twin; twin-to-twin transfusion sequence; delivery after 32 wk gestation; and inability to obtain informed consent before delivery. Fifty-five newborns (45 singleton and 10 twin infants) were enrolled.…”

“…Infants were examined supine on an open warmer in the neonatal intensive care unit with the ultrasound gel warmed to near body temperature. Because not all infants had indwelling arterial catheters and oscillometric mean blood pressure has been shown to correlate well with intra-arterial mean blood pressure (26), oscillometric blood pressure (Dynamap, Critikon, Tampa, FL, U.S.A.) was measured for all infants. Inspired oxygen concentration was adjusted to maintain pulse-oximeter saturations between 92% and 98% during the examination.…”

Blood pressure measurement using oscillometric finger cuffs in children and young adults

“…At a similar ratio of cuff width to finger circumference (41 to 48%), the digital cuff was also found to closely follow the intra-arterial pressure [9]. Moreover, in children and young adults, while the systolic pressure in the brachial artery is about 10 mmHg higher than that in the central aorta, it undergoes little or no further amplification in the radial artery [8]. The dual blood supply of the forefinger lies just downstream of the radial pulse.…”