Vascular compromise in newborn infants.

With improved neonatal resuscitation techniques a number of infants are now surviving only to develop vascular problems secondary to intravascular catheterisation, repeated venepuncture, or arterial blood sampling. Spontaneous thromboses are also more common in early life than in later childhood.' 2 Guidelines for the prevention, diagnosis, and treatment of blocked vessels in adult patients are not automatically applicable to the newborn. The size of the delicate vessels, the immature haemostatic mechanism, and the background of relative polycythaemia pose special problems. Thromboembolic vessel obstruction may result in death or irreversible damage to an organ or limb. In addition to blockage of peripheral vessels,3 4thrombosis ofthe cerebral,5 pulmonary,6 7 coronary,8 9 renal,I0 and mesenteric arteries," is reported in the neonate. Peripheral artery occlusion usually presents with a cold, pulseless, mottled, and discoloured limb. Obstruction of the central veins or arteries may be more difficult to recognise. Renal vein thrombosis, for example, does not always present with haematuria and an enlarged kidney, and thrombosis of the aorta may not disclose itself with congestive cardiac failure and ischaemia of the lower limbs.' association with radial,'9 femoral,0 pulmonary, and temporal artery22 lines, as well as with catheters into the jugular7 23 or femoral24 veins. Thrombi are also found when catheters are not used. A review of consecutive necropsies revealed a 4-5% incidence of thrombosis in uncatheterised cases, and an 11% incidence when intravascular catheters were used.25 Even temporary catherisation can cause problems. In a prospective study of children undergoing cardiac catheterisation, 3-6% developed clinical symptoms of femoral artery thrombosis.26 An extensive literature review of 1045 cannulations of the radial artery in newborn infants showed that 6% of cases suffered transient ischaemia and 0-5% had permanent ischaemic damage.27 Even hand amputation after radial artery cannulation has been reported.28 The incidence of vessel occlusion without ischaemic changes, however, is as high as 63%,29 and in such cases, an adequate collateral circulation exists. Flow in the blocked vessel is often restored several days after catheter removal. The propensity to develop thrombosis is related to size of the infant. The risk of vessel obstruction after cardiac catheterisation is highest in infants of less than 10 kg.27 30 31