The objective of the present study was to evaluate serial interleukin 6 (IL6) levels in the early diagnosis of neonatal sepsis. Subjects included 255 neonates from the Neonatal Unit of Johannesburg Hospital evaluated for suspected sepsis between February and May 1998. All infants had IL6, full blood count (FBC), C reactive protein (CRP) and blood cultures done at presentation. CRP and IL6 were repeated after 24 h. Infants were categorized into groups according to the likelihood of infection on the basis of clinical presentation, CRP, FBC and culture results, i.e., group 1 (no infection) to group 4 (definite infection). IL6 was compared between the groups by the U-test of Mann-Whitney; stepwise logistic regression was done to establish the best predictors of infection, sensitivity, specificity, positive and negative predictive values were determined. The initial IL6 level was significantly raised in those infants with possible infection [880.67 pg/ml (2966.04), p value 0.0104], probable infection [422.62pg/ml (4077.7), p value 0.0021] and definite infection [11164.39pg/ml (24139.77), p value 0.0000] as compared to those infants without infection [58.65 (182.4)]. The best predictors of infection were the combination of the initial IL6 value and CRP value after 24 h (goodness of fit 97.7 per cent). An initial IL6 value below 20 pg/ml gave a negative predictive value of 90.18 per cent. It is concluded that an IL6 value done at the time of presentation of signs and symptoms suggestive of infection is useful in the early diagnosis of neonatal sepsis. In particular, an initial IL6 value below 20 pg/ml may allow antibiotics to be withheld in a number of infants evaluated for sepsis. There is no benefit in serial determination of IL6 in the diagnosis of neonatal sepsis.

The local reflection coefficient (r) at the aortoiliac junction was estimated in vessels removed at autopsy from 15 females and 31 males aged 2 months to 88 years by calculating the characteristic impedance (ZJ) of the abdominal aorta and the two common iliac arteries. Z, was evaluated for each vessel by measuring cross-sectional area from radiographs and propagation velocity of an isolated pressure impulse generated by a solenoid-driven piston connected to the distal end of the abdominal aorta, and detected at several sites a known distance from the junction. Attenuation coefficients in the aorta were estimated from the peak amplitude of the impulse at these several sites. We observed significant decreases with age in abdominal aortic attenuation coefficient ( In children, a significant positive reflection at the distal end of the aorta will amplify the pulse wave in this region. As this vessel becomes stiffer with increasing age, amplification will increase, whereas the increasingly negative value of r will partially offset this rise, reducing pulse pressure on either side of the junction. These processes might help to minimize the adverse effects of increased vascular stiffness due to aging and disease in this part of the circulation. (Circulation 1990;82:114-123) T he magnitude of measured pressure and flow waves in the cardiovascular system is determined by the interaction of incident waves generated by the heart and one or more reflections due to junctions and, in diseased vessels, occlusive or aneurysmal lesions. Constricted muscular vessels in the peripheral circulation can cause additional reflections. Thus, to measure the magnitude of reflection coefficients, it is necessary to resolve the From measured pressure and flow wave into its generated component traveling away from the heart, a reflected wave traveling back toward the heart and, possibly, one or more rereflected waves traveling in either direction.The different approaches to this problem described in the literature can be divided into two types.' First, those in which the magnitude of all reflections distal to the measurement site are determined.2-8 These methods do not, in general, give any information about the location of particular sites of reflection but allow the calculation of a global reflection coefficient together with propagation constants (phase velocity and attenuation coefficient) of the vessel in which the measurements are made. The second class of measurements is based on the prop-