Objectives: To evaluate the prognosis of monochorionic twins with selective intrauterine growth restriction (sIUGR), classified according to the type of umbilical artery Doppler, under expectant management. Methods: The outcome of 81 cases with isolated sIUGR was evaluated according to a classification based on umbilical artery (UA) Doppler diastolic flow in the IUGR twin (I: present, II: constantly absent/reverse, III: intermittently absent/reverse). Selective feticide was not considered due to legal constraints. Perinatal outcomes included perinatal death and neurological outcome at 6 months of age. Results: From 81 cases with the diagnosis of sIUGR, twin-twin transfusion was diagnosed in 18 cases. This left 63 cases, of which 23 were classified as type I (36.5%), 27 as type II (42.9%) and 13 as type III (20.6%). Intrauterine death occurred in 4.3% (1), 29.6% (8) and 15.4% (2) among IUGR twins, and 4.3% (1), 22.2% (6) and 0.0% (0) among larger twins. Neonatal death occurred in 0.0% (0), 18.5% (5) and 0.0% (0) among IUGR twins, and 0.0% (0), 11.1% (3) and 23.0% (3) among larger twins. Neurological abnormalities at 6 months were found in 4.3% (1), 14.8% (4) and 23.1% (3) in smaller twins and 0.0% (0), 11.1% (3) and 38.5% (5) in larger twins, respectively. Intact survival at 6 months was recorded in 91% (21), 37% (10) and 61% (8) in smaller twins and 95% (22), 55% (15) and 38% (5) in larger twins, respectively. Conclusion: The outcome in monochorionic twins with sIUGR and abnormal umbilical artery Doppler is poor under expectant management. Normal Doppler seems to be associated with a good prognosis.

The survival of infants with congenital heart disease has improved dramatically. However, the incidence of neurological injury in infants surviving cardiac surgery remains considerable. These neurological sequelae are attributable at least in part to hypoxia-ischemia/reperfusion, which inevitably accompanies infant heart surgery with deep hypothermia, cardiopulmonary bypass, and circulatory arrest. To begin to identify mechanisms of brain injury during infant cardiac surgery, we used near-infrared spectroscopy to study the relationship between cerebral intravascular (hemoglobin) and mitochondrial (cytochrome aa3) oxygenation in 63 infants (aged 1 day to 9 months) undergoing deep hypothermic repair of congenital heart defects, throughout the intraoperative period. Moreover, we assessed the effect of postnatal age on these changes. The cerebral concentration of oxidized cytochrome aa3 decreased from the onset of deep hypothermic cardiopulmonary bypass, despite apparent abundant intravascular oxygenation manifested by a simultaneous increase in the cerebral concentration of oxyhemoglobin. During this interval infants older than 2 weeks had a greater decrease in oxidized cytochrome aa3 than did infants 2 weeks old or younger. During deep hypothermic circulatory arrest, cerebral levels of oxidized cytochrome aa3 remained depressed while those of oxyhemoglobin declined. With reperfusion following circulatory arrest, the recovery of oxidized cytochrome aa3 was delayed, despite a rapid recovery of intravascular oxygenation (HbO2). After rewarming and 60 minutes of reperfusion, only 46% of infants recovered to the baseline level of cerebral oxidized cytochrome aa3. These findings demonstrate a paradoxical dissociation of changes in intravascular and mitochondrial oxygenation during hypothermic cardiopulmonary bypass; a pronounced decrease of mitochondrial oxygenation is established during induction of hypothermia and a delay in recovery of mitochondrial oxygenation occurs following circulatory arrest. These effects were more pronounced in infants older than 2 weeks than in younger infants. The data suggest potentially deleterious impairments of intrinsic mitochondrial function or of delivery of intravascular oxygen to the mitochondrion or both, effects previously undetected and apparently influenced by cerebral maturation.

Objectives The aim of this study was to evaluate the use of ultrasound assessment to predict risk of mortality in expectantly managed monochorionic twin fetuses with selective intrauterine growth restriction (sIUGR). Methods

Near-infrared spectroscopy is a noninvasive monitoring technique that allows quantitative measurement of changes in cerebral oxygenated Hb (HbO,), deoxygenated Hb (Hb), total Hb, and oxidized cytochrome aa, (CytO,). Changes in cerebral Hb oxygenation and CytO, have been measured in human neonates and infants under a variety of conditions. However, the association of these measurements with cerebral high-energy phosphate loss is not known. We studied simultaneous changes in cerebral HbO,, Hb, total Hb, and CytO, by near-infrared spectroscopy and changes in nucleoside triphosphate (NTP, mostly ATP) and phosphocreatine (PC) concentrations and intracellular pH by in vivo "P-labeled magnetic resonance spectroscopy. Four-wk-old piglets (n = 8) underwent sequential hypoxic episodes of increasing severity (inspired 0, concentration, 12, 8, 6, 4, and 0%). Animals were anesthetized and mechanically ventilated. At all levels of hypoxia, cerebral HbO, decreased, and Hb increased. Loss of PC or NTP was not observed until inspired 0, concentration was decreased to less than 12%. With such severe hypoxia, hypotension, intracellular acidosis, and increasingly severe PC and NTP depletions occurred. Decreases in PC and NTP correlated closely with decreased CytO, and arterial blood pressure ( p < 0.0001) but not with changes in HbO, and Hb. In conclusion, cerebral hypoxemia is readily detected by nearinfrared spectroscopy as a decrease in HbO, and an increase in Hb. However, relative changes in cerebral HbO, and Hb have low predictive value for cerebral energy failure. Reduction of CytO, is highly correlated with decreased brain energy state and may indicate impending cellular injury. (Pediatr Res 37: 253- 259, 1995)Abbreviations NIRS, near-infrared spectroscopy HbO,, oxygenated Hb Hb, deoxygenated Hb HbT, total Hb CytO,, oxidized cytochrome aa, PC, phosphocreatine NTP, nucleoside triphosphate Pi, inorganic phosphate pHi, intracellular pH MR, magnetic resonance NMR, nuclear magnetic resonance ABG, arterial blood gas dpf, differential path-length factor Pao,, arterial Po, MAP, mean arterial pressure Episodic or sustained hypoxemia and cerebral ischemia are frequent events in critically ill neonates and infants (1, 2).These conditions may contribute to brain injury through mechanisms that include a probable initial cellular energy failure neonatal cerebral monitoring has focused on noninvasive techniques to detect the presence of cerebral hypoxemia and ischemia.NIRS is a light-based technique, which allows in vivo measurement of changes in cerebral HbO,, Hb, HbT (the sum of HbO, and Hb), and the level of CytO,. Cytochrome aa, is the terminal enzyme of the mitochondria1 electron transport chain, the site of electron transfer to molecular 0,. Because the NIRS technique is noninvasive and portable, it may provide a means to monitor cerebral oxygenation in human newborns and infants. Several investigators have demonstrated changes in NIRS measures of cerebral oxygenation in human neonates and infants during events such as apnea and bra...