Free-flow oxygen delivery to newly born infants

Resuscitation guidelines recommend administration of free-flow oxygen to newly born infants who breathe but remain cyanosed. Self-inflating resuscitation bags are described as unreliable for this purpose. We measured oxygen concentrations >or=80% delivered through a 240 mL Laerdal self-inflating resuscitation bag and from 5 mm tubing inside a cupped hand.     

Supplemental inhaled gases alter tidal volume delivery and measurement.

OBJECTIVE: Supplemental inspired nitrogen (N(2)) or carbon dioxide (CO(2)) is commonly used to balance pulmonary blood flow in patients with single-ventricle physiology. The objective of this study was to assess if supplemental inspired gas alters delivery or measurement of tidal volume (V(T)) by a ventilator. DESIGN: Prospective, experimental study. SETTING: Respiratory Care Laboratory, Cincinnati Children's Hospital. INTERVENTIONS: Using a test lung, expired V(T) measurements from Servo 300 ventilators were compared with actual delivered V(T) (true V(T)) at baseline and during supplemental N(2) or CO(2) administration to mimic clinical use in single-ventricle patients. At compliance settings simulating normal and compromised lung function, true V(T) was determined by the test lung and inline Pneumotach. True and measured V(T) were compared by repeated-measures analysis of variance with significance defined as p < .05. MEASUREMENTS AND MAIN RESULTS: With normal lung compliance, supplemental gas administration increases both true and measured V(T), and expired V(T) measurements remain accurate. With poor lung compliance, supplemental gas flow disproportionately affects V(T) measurement. Poor lung compliance reduces true V(T) markedly (p < .001), causing a large discrepancy between true and measured V(T). Supplemental gas administration amplifies this discrepancy because the additional gas flow in the circuit erroneously augments expired V(T) measurements by the ventilator (p < .001). The discrepancy is greatest with higher-set V(T) and greater supplemental gas flow. CONCLUSIONS: The addition of supplemental inspired gas directly into the ventilator circuit can alter tidal volume delivery or measurement by a ventilator. The extent and magnitude of the alterations are determined by lung compliance. Variable effects of supplemental gas administration may confound ventilator management of patients with single-ventricle physiology.     

基于产前诊断的产房外科模式下新生儿急诊手术

目的 探讨产房外科模式开展新生儿手术的组织实施及其对预后的影响.方法 回顾性分析22例产房外科手术病例的产前诊断、产前咨询、手术治疗、术后合并症以及预后情况.结果 22例中,脐膨出6例,腹裂4例,先天性膈疝7例,颈部淋巴管瘤2例,泄殖腔外翻1例,腰骶部脊膜膨出2例.所有患儿产前诊断与手术后诊断相符.均顺利完成手术,其中3例膈疝患儿术后死于肺发育不良,脐膨出和泄殖腔外翻各1例需2次手术,1例颈部淋巴管瘤术后复发.结论 在产前诊断明确后,合理选择产房外科模式实施手术可以改善严重结构异常新生儿的预后,减少并发症.     

Errors in low flow oxygen delivery systems

Abstract Accurate delivery of low flow oxygen is essential for the management of infants with chronic respiratory failure. Twenty-seven examples of one low flow oxygen meter were tested. Measured flows were found to differ greatly from indicated settings, particularly at 250 mL/min settings. Knowledge of such errors as well as improved quality control are essential for appropriate management of oxygen therapy.     

Errors in low flow oxygen delivery systems

Accurate delivery of low flow oxygen is essential for the management of infants with chronic respiratory failure. Twenty-seven examples of one low flow oxygen meter were tested. Measured flows were found to differ greatly from indicated settings, particularly at 250 mL/min settings. Knowledge of such errors as well as improved quality control are essential for appropriate management of oxygen therapy.     

Skin to calcaneus distance in the neonate

BACKGROUND: Current recommendations for obtaining blood from neonates advise avoidance of the midline area of the heel and are based on postmortem studies. OBJECTIVE: Because of the potential pain and tissue damage from repeated heel pricking in the same area, to investigate using ultrasonography whether the distance from skin to calcaneus is less at the midline than at the borders. METHODS: One hundred consecutive healthy preterm and 105 consecutive healthy term neonates were studied 48-72 hours after delivery. The skin to perichondrium distance (SPD) was measured on two occasions by ultrasound at the external, midline, and internal areas of the heel. FINDINGS: Mean SPD was 0.2 mm less at the midline than at the other sites. The proportion of measurements <3 mm at any of the three sites was the same. Depth was <3 mm in less than 3% of the term and approximately 20% of the preterm infants. The SPD correlated only with gestational age. Of children <33 weeks gestational age, 38% had an SPD <3 mm compared with 8% of older preterm infants. The proportions of preterm infants of > or = 33 weeks gestation and term infants with an SPD <3 mm were similar (8% v 3%). INTERPRETATION: With the use of automated lancets of 2.2 mm length or less, the whole heel plantar surface is safe for obtaining blood in term and preterm infants of > or = 33 weeks gestation. This means that soft tissue damage and pain from repeated pricking in the same area can be reduced.     

Variability in cerebral oxygen delivery is reduced in premature neonates exposed to chorioamnionitis

Premature infants exposed to chorioamnionitis are at increased risk for periventricular leukomalacia (PVL) and intraventricular hemorrhage (IVH), lesions that may result from inflammation and/or fluctuations in cerebral blood flow. The effect of chorioamnionitis on near-infrared spectroscopy (NIRS) measures of cerebral oxygen delivery has not been evaluated previously. Forty-nine infants born at 25-31 6/7 wk gestation underwent NIRS examination on d 1, 2, 3, and 7 of life. Variability in NIRS tracings was analyzed by partitioning each tracing into three components: long-term, intermediate, and short-term variability; the latter two components were analyzed. Chorioamnionitis-exposed infants manifest reduced intermediate variability in cerebral oxygenated and deoxygenated Hb but not total Hb. Infants with severe IVH/PVL had the lowest intermediate variability on d 1. Short-term variability was similar between chorioamnionitis-exposed and unexposed infants, and between infants with versus without severe IVH or PVL. We conclude that intermediate-term variability in NIRS cerebral oxygen delivery is reduced in chorioamnionitis-exposed infants. We speculate that intermediate variability represents the important time frame for evaluating the pathogenesis of perinatal brain injury. Further studies are needed to determine how these findings relate to cerebral blood flow autoregulation and oxygen utilization in premature infants.     

Blood flow and oxygen delivery to the organs of the neonatal lamb as a function of hematocrit

We chronically catheterized 15 newborn lambs (9.5 +/- 2.8 days) and measured the distribution of cardiac output by the radionuclide-microsphere technique at hematocrits ranging from 10 volumes % to 55 volumes %. Seven animals were made progressively anemic and eight polycythemic by means of exchange transfusions. Cardiac output and heart rate increased with decreasing hematocrit while whole body oxygen consumption showed a small decrease during severe anemia. Both cerebral and cardiac blood flow markedly increased during anemia which assured a relatively stable oxygen delivery to both organs. The changes seen for blood flow to the carcass (skin, bones, and muscle) were predictable from the effects of blood viscosity: small decreases in flow at the highest hematocrits and small increases in flow at the lowest hematocrits. Consequently, oxygen delivery was as low as 1 ml of oxygen/min/100 g at a hematocrit of 10 volumes %. Renal blood flow remained unchanged while oxygen delivery fell when hematocrit was decreased. Hepatic oxygenation was measured using a modification of the Fick principle. Hepatic blood flow showed only a small decrease as hematocrit increased and changed minimally during anemia resulting in a falling delivery of oxygen with anemia. A stable hepatic oxygen consumption was assured by a marked increase in oxygen extraction during anemia. Two differing organ responses to changes in hematocrit can be seen in the newborn: the brain and heart vary blood flow to assure an adequate delivery of oxygen while a number of other organs show less blood flow regulation and, most likely, vary oxygen removal from blood.(ABSTRACT TRUNCATED AT 250 WORDS)     

Approach to congenital heart disease in the neonate

Congenital heart disease in the newborn is a unique and complex problem faced by both pediatricians and cardiologists as it requires skillful handling and balancing of both neonatal issues as well as cardiac physiology. Babies with cyanotic and acyanotic heart disease are physiologically different from each other and management has to be tailored to the individual diagnosis and clinical status. Rapid diagnosis and appropriate management is the key to reducing mortality and morbidity in this fragile patient population. The following review deals with the common presentations of heart problems in a newborn baby and methods of diagnosis, investigative modalities, recent advances and approach to management     

新生儿呼吸衰竭时氧交换指标监测的临床意义

目的 探讨新生儿呼吸衰竭时氧交换指标动态监测在临床的意义。方法对新生儿重症监护病房接受呼吸机治疗的120例呼吸衰竭新生儿，予行血气、动脉氧分压与吸入氧浓度之比、动脉／肺泡氧分压比值、肺泡-动脉氧分压差、呼吸指数等指标的动态监测，并根据其病情分组进行对比观察。结果轻度呼吸衰竭组与重度呼吸衰竭组两组间各项氧交换指标均有显著性差异（P〈0．05）；生存组治疗前与治疗24h后的氧交换指标比较，有非常显著性差异（P〈0．001）；死亡组治疗前与治疗24h后动脉／肺泡氧分压比值变化差异无显著性（P〉0．05）。结论应用氧交换指标对呼吸衰竭的新生儿进行临床评估，对判断病情、指导治疗和估计预后有重要意义。     

Strategies to prevent CMV infection in the neonate

Congenital cytomegalovirus (CMV) infection is a major cause of sensorineural hearing loss and mental retardation, whose annual healthcare costs in the USA approximate to one billion dollars. Only a minority of neonates with this infection has symptoms present at birth and some of the damage to ear and brain occurs in the first few months of life. Extensive studies of CMV infection have been conducted in pregnant women and their children to define the natural history of this infection. What is required now is a concerted commitment to tackle this clinical problem using one or more of the following strategies: avoid iatrogenic transmission; advise those at risk how to avoid acquisition; provide diagnosis in an individual neonate or pregnant woman and offer treatment; develop and deploy a CMV vaccine.