An estimation of intracranial blood flow in the new‐born infant.

Abstract

4. The jugular veins in the baby's neck are occluded by finger pressure and there follows an increase in skull volume, which is rapid at first, but which decreases exponentially as venous drainage diverts to non-occluded channels such as the vertebral venous plexus. At the instant of jugular occlusion the rate of skull volume increase is representative of the rate of flow in the jugular vessels prior to occlusion, and so provides an index of the relative magnitude of the intracranial blood flow. The method thus allows changes in intracranial blood flow to be followed. When occlusion is released cranial volume decreases, initially rapidly, but slowing exponentially as resting volume is regained.5. A theoretical model of the events occurring during the inflow and outflow phases has been developed, and a formula derived which allows an estimation to be made of the flow of blood through uncompressed channels. The measured value of jugular blood flow can then be augmented to an estimate of total intracranial flow.6. The mean cerebral blood flow of sixteen normal babies was estimated to be 40 ml. 100 g-1. min-' (S.D. = + 11t63).

An evaluation of the plethysmographic method of measuring cranial blood flow in the new‐born infant.

“…value for each baby is the mean of values obtained in ten successive jugular venous compressions. The range of values usually obtained in a series of ten from one baby was much greater than we would expect as normal physiological variation (see Table 2 and Cross et al 1979). Continuous ultrasound recording of blood velocities in the internal carotid arteries in adults gives rather stable values (Hauge, Thoresen & Wall0e, 1980;Hauge, Nicolaysen & Thoresen, 1982).…”

“…The coefficients of variation for the exponential fit method and the slope method are 0 17 and 0'13, respectively. (Tominaga, Strandgaard, Uemura, Ito, Kutsuzawa, Lassen & Nakamura, 1976;Cross et al 1979;Rahilly, 1980b). Cross and co-workers give a mean c.b.f.…”

“…Jugular venous occlusion plethysmography was performed in the manner described by C(ross (Cross et al 1979), the baby being placed supine on an assistant's lap with his head free of contact with any external object and supported at the base of the neck by the assistant's fingers. A mercury-in-silastic strain-gauge was placed around the fronto-occipital head circumference of the just-fed, naturally sleeping infant, and the jugular compressions performed by the operator's index fingers placed just above the medial end of the clavicles.…”

“…Cross and others later tried to estimate the total arterial inflow by means of a simple electrical analogue model of the cranial venous drainage (Cross, Dear, Hathorn, Hyams, Kerslake, Milligan, Rahilly & Stothers, 1979). If the assumptions underlying the model are valid, both the volume increase of the skull after jugular occlusion and the decrease after release should follow an exponential time course, though each with a different time constant.…”

A Comparison between Electrical Impedance and Strain Gauge Plethysmography for the Study of Cerebral Blood Flow in the Newborn

“…These include 1) monitoring intracranial pressure by placing a transducer over the anterior fontanelle (22), 2) using ultrasound to measure blood flow velocity in the anterior cerebral artery (1,2), and 3) jugular venous occlusion plethysmography using a strain gauge around the OFC (3,4).…”