Umbilical artery catheters in the newborn: effects of position of the catheter tip

Outcomes of Femoral Arterial Catheterisation in Neonates: A Retrospective Cohort Study

Background: To review the outcome of all femoral arterial catheter (FAC) insertions in a single, large neonatal unit over a 12 year period, we will describe the incidence of harms arising from FAC insertion and to identify risk factors associated with ischaemic injury. Methods: Retrospective survey of data relating to all episodes of FAC insertion in a single neonatal intensive care unit over a 12 year period up to 2020. Results: 146 FACs were inserted into 139 babies with a median (interquartile range) gestation and birth weight of 27 (24 to 37) weeks and 1092 (682 to 2870) g. Impaired limb perfusion occurred in 32 (22%). This was transient and recovered with no injury in 26 of the 32. There was an increased risk of impaired limb perfusion in babies with lower weight at the time of insertion; from 5.7% in babies over 3000 g to 34.7% in babies under 1000 g (relative risk 6.1 (1.5 to 24.6)). Six babies (4%) had ischaemic injury. Risk factors for ischaemic injury included weight below 1000 g (four cases), pre-existing partial arterial obstruction (two cases), concerns about limb perfusion prior to FAC insertion (two cases) and a delay in removing the FAC after recognition of the poor perfusion (five cases). Two clinicians inserted 71 (50%) FACs and had no associated injuries. Conclusions: FAC can be used in neonates, although there is a risk of ischaemic injury, particularly in very small babies. Our data can be used to inform decisions about patient selection for this procedure.

The undulating line sign and other more common pediatric central catheter malpositions

Central venous and arterial catheters are among the most commonly assessed support devices by radiologists. The position of these catheters must be carefully assessed to ensure proper placement, as malpositioning may lead to life-threatening consequences. Therefore, it is important for radiologists to understand the anatomy of the central vessels and the expected location of catheters. While this can be difficult in small children and especially in neonates, knowledge of the expected course and ideal termination of catheters allows for recognition of a malpositioned line, which may be unsuspected clinically. The purpose of this article is to discuss appropriate positioning of central catheters in pediatric patients, focusing primarily on venous catheters. We also propose a new radiographic sign to recognize, the undulating line sign, as an indication of an inappropriate course of a newly placed venous catheter.

Systemic Hypertension in Infants with Bronchopulmonary Dysplasia

PURPOSE OF REVIEW

Neonatal hypertension is increasingly recognized as improvements in neonatal intensive care have led to increased survival of premature infants. Among infants with bronchopulmonary dysplasia (BPD), the rates of hypertension are much higher than the general neonatal population. However, the etiology and pathophysiology of this increased risk of hypertension in neonates with lung disease remain unclear.

RECENT FINDINGS

Among infants with bronchopulmonary dysplasia, the rates of hypertension are much higher than the general neonatal population. New studies suggest outcomes in neonates with BPD with hypertension are usually good, with resolution of hypertension in most infants with lung disease. Several potential mechanisms of hypertension in this patient population have been recently proposed. This review focuses on the recent epidemiologic data on prevalence of hypertension in neonates with bronchopulmonary dysplasia, reviews the typical clinical course, and discusses available strategies for management of infants with bronchopulmonary dysplasia that develop hypertension.

Management of Acute Kidney Injury in Extremely Low Birth Weight Infants

Acute kidney injury (AKI) is a common problem in the neonatal intensive care unit (NICU). Neonates born at <1,000 g (extremely low birth weight, ELBW) are at an increased risk of secondary associated comorbidities such as intrauterine growth restriction, prematurity, volume restriction, ischaemic injury, among others. Studies estimate up to 50% ELBW infants experience at least one episode of AKI during their NICU stay. Although no curative treatment for AKI currently exists, recognition is vital to reduce potential ongoing injury and mitigate long-term consequences of AKI. However, the definition of AKI is imperfect in this population and presents clinical challenges to correct identification, thus contributing to under recognition and reporting. Additionally, the absence of guidelines for the management of AKI in ELBW infants has led to variations in practice. This review summarizes AKI in the ELBW infant and includes suggestions such as close observation of daily fluid balance, review of medications to reduce nephrotoxic exposure, management of electrolytes, maximizing nutrition, and the use of diuretics and/or dialysis when appropriate.

How Do We Monitor Oxygenation during the Management of PPHN? Alveolar, Arterial, Mixed Venous Oxygen Tension or Peripheral Saturation?

Oxygen is a pulmonary vasodilator and plays an important role in mediating circulatory transition from fetal to postnatal period. Oxygen tension (PO₂) in the alveolus (PAO₂) and pulmonary artery (PaO₂) are the main factors that influence hypoxic pulmonary vasoconstriction (HPV). Inability to achieve adequate pulmonary vasodilation at birth leads to persistent pulmonary hypertension of the newborn (PPHN). Supplemental oxygen therapy is the mainstay of PPHN management. However, optimal monitoring and targeting of oxygenation to achieve low pulmonary vascular resistance (PVR) and optimizing oxygen delivery to vital organs remains unknown. Noninvasive pulse oximetry measures peripheral saturations (SpO₂) and a target range of 91-95% are recommended during acute PPHN management. However, for a given SpO₂, there is wide variability in arterial PaO₂, especially with variations in hemoglobin type (HbF or HbA due to transfusions), pH and body temperature. This review evaluates the role of alveolar, preductal, postductal, mixed venous PO₂, and SpO₂ in the management of PPHN. Translational and clinical studies suggest maintaining a PaO₂ of 50-80 mmHg decreases PVR and augments pulmonary vasodilator management. Nevertheless, there are no randomized clinical trials evaluating outcomes in PPHN targeting SpO₂ or PO₂. Also, most critically ill patients have umbilical arterial catheters and postductal PaO₂ may not be an accurate assessment of oxygen delivery to vital organs or factors influencing HPV. The mixed venous oxygen tension from umbilical venous catheter blood gas may assess pulmonary arterial PO₂ and potentially predict HPV. It is crucial to conduct randomized controlled studies with different PO₂/SpO₂ target ranges for the management of PPHN and compare outcomes.

Nutritional support for children during critical illness: European Society of Pediatric and Neonatal Intensive Care (ESPNIC) metabolism, endocrine and nutrition section position statement and clinical recommendations

Background

Nutritional support is considered essential for the outcome of paediatric critical illness. There is a lack of methodologically sound trials to provide evidence-based guidelines leading to diverse practices in PICUs worldwide. Acknowledging these limitations, we aimed to summarize the available literature and provide practical guidance for the paediatric critical care clinicians around important clinical questions many of which are not covered by previous guidelines.

Objective

To provide an ESPNIC position statement and make clinical recommendations for the assessment and nutritional support in critically ill infants and children.

Design

The metabolism, endocrine and nutrition (MEN) section of the European Society of Pediatric and Neonatal Intensive Care (ESPNIC) generated 15 clinical questions regarding different aspects of nutrition in critically ill children. After a systematic literature search, the Scottish Intercollegiate Guidelines Network (SIGN) grading system was applied to assess the quality of the evidence, conducting meta-analyses where possible, to generate statements and clinical recommendations, which were then voted on electronically. Strong consensus (> 95% agreement) and consensus (> 75% agreement) on these statements and recommendations was measured through modified Delphi voting rounds.

Results

The final 15 clinical questions generated a total of 7261 abstracts, of which 142 publications were identified relevant to develop 32 recommendations. A strong consensus was reached in 21 (66%) and consensus was reached in 11 (34%) of the recommendations. Only 11 meta-analyses could be performed on 5 questions.

Conclusions

We present a position statement and clinical practice recommendations. The general level of evidence of the available literature was low. We have summarised this and provided a practical guidance for the paediatric critical care clinicians around important clinical questions.

Electronic supplementary material

The online version of this article (10.1007/s00134-019-05922-5) contains supplementary material, which is available to authorized users.

Neonatal hypertension: cases, causes, and clinical approach

Neonatal hypertension is increasingly recognized as dramatic improvements in neonatal intensive care, advancements in our understanding of neonatal physiology, and implementation of new therapies have led to improved survival of premature infants. A variety of factors appear to be important in determining blood pressure in neonates, including gestational age, birth weight, and postmenstrual age. Normative data on neonatal blood pressure values remain limited. The cause of hypertension in an affected neonate is often identified with careful diagnostic evaluation, with the most common causes being umbilical catheter-associated thrombosis, renal parenchymal disease, and chronic lung disease. Clinical expertise may need to be relied upon to decide the best approach to treatment in such patients, as data on the use of antihypertensive medications in this age group are extremely limited. Available data suggest that long-term outcomes are usually good, with resolution of hypertension in most infants. In this review, we will take a case-based approach to illustrate these concepts and to point out important evidence gaps that need to be addressed so that management of neonatal hypertension may be improved.

A critical analysis of risk factors for necrotizing enterocolitis

Necrotizing enterocolitis (NEC) is the most common serious gastrointestinal morbidity in preterm infants. A number of risk factors for NEC have been reported in the literature. With the exception of decreasing gestational age, decreasing birth weight and formula feeding, there is disagreement on the importance of reported risk factors with uncertain causality. Causal risk factors may be observed at any time before the onset of NEC, including prior to an infant's birth. The purpose of this review is to examine the existing literature and summarize risk factors for NEC. This review may be helpful in understanding the epidemiology of NEC and inform the measurement and assessment of risks factors for NEC in research studies and quality improvement projects.

Sonographic features of umbilical catheter-related complications

Umbilical catheters are commonly used in the neonatal period for blood sampling or for administering medication or parenteral nutrition. The position of the catheter is usually confirmed with radiography. However, many complications associated with the use of umbilical catheters, such as liver collections from extravasation or vascular thrombosis, are not apparent on radiographs but can be easily diagnosed with ultrasound. This pictorial review illustrates the sonographic findings of complications that should be excluded in the sick neonate with an indwelling catheter.

The Effect of Continuous Intravenous Glucagon on Glucose Requirements in Infants with Congenital Hyperinsulinism

BACKGROUND/AIMS

Continuous intravenous glucagon is frequently used in the management of severe congenital hyperinsulinism (HI), but its efficacy in these patients has not been systematically evaluated. The aim of this study was to describe the use of continuous intravenous glucagon and to evaluate its effect on the glucose infusion rate (GIR) requirement in infants with HI.

METHODS

Retrospective chart review of children with HI who received continuous intravenous glucagon for prevention of hypoglycemia at the Children's Hospital of Philadelphia between 2003 and 2013.

RESULTS

Forty (22 male) infants were included, and median (IQR) age at glucagon treatment was 29 (23, 54) days. Median glucagon dose was 205 (178, 235) mcg/kg/day and duration of treatment was 5 (3, 9) days. GIR reduced from 18.5 (12.9, 22.8) to 11 (6.6, 17.5) mg/kg/min 24 h after starting glucagon (p < 0.001), and hypoglycemia frequency reduced from 1.9 (1.3, 2.9) to 0.7 (0.3, 1.2) episodes per day. Vomiting (n = 11, 13%), rash (n = 2, 2%), and respiratory distress (n = 15, 19%) were seen during glucagon treatment.

CONCLUSION

An intravenous glucagon infusion reduces the required GIR to maintain euglycemia, decreasing the risks associated with the administration of high fluid volume or fluids with high-glucose concentrations.

Optimal Line and Tube Placement in Very Preterm Neonates: An Audit of Practice

BACKGROUND

Placement of endotracheal tubes (ETTs) and umbilical catheters (UCs) is essential in very preterm infant care. The aim of this study was to assess the effect of an educational initiative to optimize correct placement of ETTs and UCs in very preterm infants.

METHODS

A pre-post study design, evaluating optimal radiological position of ETTs and UCs in the first 72 h of life in infants <32 weeks gestational age (GA) was performed. Baseline data was obtained from a preceding 34-month period. The study intervention consisted of information from the pre-intervention audit, surface anatomy images of the newborn for optimal UC positioning, and weight-based calculations to estimate insertion depths for endotracheal intubation. A prospective evaluation of radiological placement of ETTs and UCs was then conducted over a 12-month period.

RESULTS

During the study period, 211 infants had at least one of the three procedures performed. One hundred and fifty-seven infants were included in the pre-education group, and 54 in the post-education group. All three procedures were performed in 50.3% (79/157) in the pre-education group, and 55.6% (30/54) in the post-education group. There was no significant difference in accurate placement following the introduction of the educational sessions; depth of ETTs (50% vs. 47%), umbilical arterial catheter (UAC) (40% vs. 43%,), and umbilical venous catheter (UVC)(14% vs. 23%).

CONCLUSION

Despite education of staff on methods for appropriate ETT, UVC and UAC insertion length, the rate of accurate initial insertion depth remained suboptimal. Newer methods of determining optimal position need to be evaluated.

Late Presentation of Fulminant Necrotizing Enterocolitis in a Child with Hyperinsulinism on Octreotide Therapy

Congenital hyperinsulinism (HI) is the most common cause of persistent hypoglycemia in infants and children. In cases of diazoxide-unresponsive HI, alternative medical and surgical approaches may be required to reduce the risk of hypoglycemia. Octreotide, a somatostatin analog, often has a role in the management of these children, but a dose-dependent reduction in splanchnic blood flow is a recognized complication. Necrotizing enterocolitis (NEC) has been reported within the first few weeks of initiating predominantly high doses of octreotide. We describe the case of an infant with Beckwith-Wiedemann syndrome and diazoxide-unresponsive HI, who had persistent hypoglycemia after two pancreatectomy surgeries. She developed NEC 2 months after beginning octreotide therapy at a relatively low dose of 8 µg/kg/day. This complication has occurred later, and at a lower dose, than has previously been described. We review the case and identify the known and suspected multifactorial risk factors for NEC that may contribute to the development of this complication in patients with HI.

Simple measurements to place umbilical catheters using surface anatomy

OBJECTIVE

To use external anatomical landmarks to determine a new method for the estimation of appropriate insertion length of umbilical catheters, suitable for newborn infants of varying birth weight (BW) and gestational age.

STUDY DESIGN

Neonates who had umbilical venous (UVC) or arterial (UAC) catheters placed soon after birth were included in the study. Catheters were placed using formulas derived by Shukla (1986) and/or Wright (2007), and adjusted to appropriate positions confirmed radiologically: UAC tip between T6-T10 vertebral bodies and UVC at the level of the diaphragm±0.5 cms. Final catheter length was compared with the length estimated by Shukla/Wright formulas and to four additional morphometric measurements: umbilicus to nipple (UN), umbilicus to midpoint of inter-mammary distance, umbilicus to xiphoid process and umbilicus to symphysis pubis (USp).

RESULT

Of 216 infants, 32 were excluded; UVC was placed in 170 infants and UAC in 125 infants. Among the morphometric measurements, UN-1 cm ( UN distance minus 1 cm) provided the best estimate of accurate insertion length of UVC, (r=0.984, P<0.001) and estimated correct insertion length of 94% of UVCs compared with 57% accuracy with Shukla formula for all BW categories (P<0.001). Morphometric measurement UN-1+2 USp (UN distance minus 1 cm plus twice the distance from umbilicus to symphysis pubis) showed significantly better correlation with appropriate insertion length of UAC (r=0.985, P<0.001) and estimated correct insertion length of 92% of UACs in all infants as compared with 57% accuracy with Shukla formula (P<0.001), and the correct insertion length in 94% of very low BW infants as compared with 68% accuracy with Wright formula (P<0.001).

CONCLUSION

Simple and intuitive morphometric measurements UN and USp provide more accurate estimates of appropriate insertion lengths for umbilical catheters in infants with all BWs than commonly used BW-based formulas.

Radiographic assessment of umbilical venous and arterial catheter tip location

Umbilical venous and arterial catheters are routinely used in the care of critically ill patients in neonatal intensive care settings. Providers caring for these vulnerable patients have a role in ensuring that catheter tips remain in an appropriate position. The ideal anatomic tip location for both types of umbilical catheters is reviewed, and the evaluation of this position via radiographic study is discussed. Umbilical venous catheters (UVCs) and umbilical arterial catheters (UACs) have their own different complications. Complications of a malpositioned catheter of either type can be life threatening; therefore, evaluation of catheter tip location is an important skill in the provision of neonatal intensive care.

Topical Nitroglycerine for Neonatal Arterial Associated Peripheral Ischemia following Cannulation: A Case Report and Comprehensive Literature Review

Arterial cannulation in neonates is usually performed for frequent blood pressure monitoring and blood sampling. The procedure, while easily executed by skilled neonatal staff, can be associated with serious complications such as vasospasm, thrombosis, embolism, hematoma, infection, peripheral nerve damage, ischemia, and tissue necrosis. Several treatment options are available to reverse vascular induced ischemia and tissue damage. Applied interventions depend on the extent of tissue involvement and whether the condition is progressive and deemed life threatening. Standard, noninvasive measures include immediate catheter removal, limb elevation, and warming the contralateral extremity. Topical vasodilators, anticoagulation, thrombolysis, and surgery are considered secondary therapeutic strategies. A comprehensive literature search indicates that topical nitroglycerin has been utilized for the treatment of tissue ischemia in three preterms with umbilical arterial catheters and four with peripheral arterial lines. We report the first successful use of nitroglycerine ointment in a critically ill preterm infant with ischemic hand changes after brachial artery cannulation.

Umbilical arterial catheter insertion length: in quest of a universal formula

OBJECTIVE

The study was aimed at comparing the accuracy in length of insertion of umbilical arterial catheter in all new born groups stratified according to weight, by using two different methods, that is, Wright et al./Case (Group I): (4 × Body wt (BW) (kg)) +7; Shukla et al./Control (Group II): (3 × BW (kg)) +9.

STUDY DESIGN

It was a randomized open label case control study in a Level III tertiary level Neonatal Intensive Care Unit over 9 months.

RESULT

The babies in both the groups were similar in relation to weight, gender, prematurity and weight subgroups. Under insertion was seen in 8% (4/50) of babies in group I and over insertion was seen in group II where it was 32.6% (16/49). There was a reduction of 82% abnormal insertions and repositioning by using the Wright's formula as compared with the Shukla's formula in preterm babies. Statistically significant reduction in repositioning was seen in all babies <1500 g in Group I and under insertion seen in 8% of babies in group I did not attain statistical significance (P=0.34).

CONCLUSIONS

There is no universal formula, which gives the accurate length of placement of an umbilical arterial catheter, but Wright's formula comes closer in neonates with different weight sub groups.

Hypertension in infancy: diagnosis, management and outcome

Advances in the ability to identify, evaluate, and care for infants with hypertension, coupled with advances in the practice of Neonatology, have led to an increased awareness of hypertension in modern neonatal intensive care units. This review will present updated data on blood pressure values in neonates, with a focus on the changes that occur over the first days and weeks of life in both term and preterm infants. Optimal blood pressure measurement techniques as well as the differential diagnosis of hypertension in the neonate and older infants will be discussed. Recommendations for the optimal immediate and long-term evaluation and treatment, including potential treatment parameters, will be presented. We will also review additional information on outcome that has become available over the past decade.

[Malpositioning of umbilical vessel catheters]

BACKGROUND

Catheterization of umbilical veins and arteries is a common intervention in newborns. Malpositioning of catheters is associated with complications. The objective of this study was to evaluate catheter positions after insertion.

MATERIAL AND METHODS

The study is based on retrospective evaluation of all relevant X-ray images of newborns admitted to the neonatal intensive care unit, Vestfold Hospital, Norway in the period 1.06.98 - 28.02.10. Accurate localization of the catheter tip was determined in all images. In term infants, acceptable positioning for venous catheters was defined as <or= 10 mm above or below the level of diaphragma and in preterm infants <or= 5 mm. For arterial catheters, acceptable positioning of the catheter tip (irrespective of gestational age) was at the level of the 6th to 9th thoracic vertebral body (high position, preferred) or at the 3rd to 4th lumbar vertebral body (low position).

RESULTS

278 umbilical vein and 99 umbilical artery catheters were inserted in 298 patients. 45/99 (45 %) of the arterial catheters and 77/278 (28 %) of the venous catheters were correctly positioned from the start. Significantly more arterial catheters were positioned too low (44/99; 44 %) than too high (10/99; 10 %) (p < 0.001). Correspondingly, more venous catheters were positioned too low (126/278; 45 %) than too high (75/278; 27 %) (p < 0.001). Coiling occurred in 14 (5 %) venous catheters and in 6 (6 %) arterial catheters.

INTERPRETATIONS

Umbilical vessel catheters are often malpositioned. This increases the risk of thromboses and circulation disturbances. X-ray images are important for evaluation and potential correction of the catheter position.

Poor accuracy of methods currently used to determine umbilical catheter insertion length

This study compares the methods of Dunn and Shukla in determining the appropriate insertion length of umbilical catheters. In July 2007, we changed our policy for umbilical catheter insertions from the method of Dunn to the method of Shukla. We report our percentage of inaccurate placement of umbilical-vein catheters (UVCs) and umbilical-artery catheters (UACs) before and after the change of policy. In the Dunn-group, 41% (28/69) of UVCs were placed directly in the correct position against 24% (20/84) in the Shukla-group. The position of the catheter-tip of UVCs in the Dunn-group and the Shukla-group was too high in 57% (39/69) and 75% (63/84) of neonates, respectively. UACs in the Dunn-group were placed directly in the correct position in 63% (24/38) compared to the 87% (39/45) of cases in Shukla-group. The position of the catheter-tip of UACs in the Dunn-group and the Shukla-group was too high in 34% (13/38) and 13% (6/45) of neonates, respectively. In conclusion, the Dunn-method is more accurate than the Shukla-method in predicting the insertion length for UVCs, whereas the Shukla-method is more accurate for UACs.

The evaluation and management of postnatal thromboses

In the pediatric population, neonates have the highest risk for thromboembolism (TE), most likely due to the frequent use of intravascular catheters. This increased risk is attributed to multiple risk factors. Randomized clinical trials dealing with management of postnatal thromboses do not exist, thus, opinions differ regarding optimal diagnostic and therapeutic interventions. This review begins with an actual case study illustrating the complexity and severity of these types of cases, and then evaluates the neonatal hemostatic system with discussion of the common sites of postnatal thrombosis, perinatal and prothrombotic risk factors, and potential treatment options. A proposed step-wise evaluation of neonates with symptomatic postnatal thromboses will be suggested, as well as future research and registry directions. Owing to the complexity of ischemic perinatal stroke, this topic will not be reviewed.

Thrombosis in the critically ill neonate: incidence, diagnosis, and management

Among children, newborn infants are most vulnerable to development of thrombosis and serious thromboembolic complications. Amongst newborns, those neonates who are critically ill, both term and preterm, are at greatest risk for developing symptomatic thromboembolic disease. The most important risk factors are inflammation, DIC, impaired liver function, fluctuations in cardiac output, and congenital heart disease, as well as exogenous risk factors such as central venous or arterial catheters. In most clinically symptomatic infants, diagnosis is made by ultrasound, venography, or CT or MRI angiograms. However, clinically asymptomatic vessel thrombosis is sometimes picked up by screening investigations or during routine imaging for other indications. Acute management of thrombosis and thromboembolism comprises a variety of approaches, including simple observation, treatment with unfractionated or low molecular weight heparin, as well as more aggressive interventions such as thrombolytic therapy or catheter-directed revascularization. Long-term follow-up is dependent on the underlying diagnosis. In the majority of infants, stabilization of the patients’ general condition and hemodynamics, which allows removal of indwelling catheters, renders long-term anticoagulation superfluous. Nevertheless, in certain types of congenital heart disease or inherited thrombophilia, long-term prophylaxis may be warranted. This review article focuses on pathophysiology, diagnosis, and acute and long-term management of thrombosis in critically ill term and preterm neonates.

Validation of Oxygen Saturation Monitoring in Neonates

•Background Pulse oximetry is commonly used to monitor oxygenation in neonates, but cannot detect variations in hemoglobin. Venous and arterial oxygen saturations are rarely monitored. Few data are available to validate measurements of oxygen saturation in neonates (venous, arterial, or pulse oximetric).

•Purpose To validate oxygen saturation displayed on clinical monitors against analyses (with correction for fetal hemoglobin) of blood samples from neonates and to present the oxyhemoglobin dissociation curve for neonates.

•Method Seventy-eight neonates, 25 to 38 weeks’ gestational age, had 660 arterial and 111 venous blood samples collected for analysis.

•Results The mean difference between oxygen saturation and oxyhemoglobin level was 3% (SD 1.0) in arterial blood and 3% (SD 1.1) in venous blood. The mean difference between arterial oxygen saturation displayed on the monitor and oxyhemoglobin in arterial blood samples was 2% (SD 2.0); between venous oxygen saturation displayed on the monitor and oxyhemoglobin in venous blood samples it was 3% (SD 2.1) and between oxygen saturation as determined by pulse oximetry and oxyhemoglobin in arterial blood samples it was 2.5% (SD 3.1). At a Pao2 of 50 to 75 mm Hg on the oxyhemoglobin dissociation curve, oxyhemoglobin in arterial blood samples was from 92% to 95%; oxygen saturation was from 95% to 98% in arterial blood samples, from 94% to 97% on the monitor, and from 95% to 97% according to pulse oximetry.

•Conclusions The safety limits for pulse oximeters are higher and narrower in neonates (95%–97%) than in adults, and clinical guidelines for neonates may require modification.

Validation of oxygen saturation monitoring in neonates

BACKGROUND

Pulse oximetry is commonly used to monitor oxygenation in neonates, but cannot detect variations in hemoglobin. Venous and arterial oxygen saturations are rarely monitored. Few data are available to validate measurements of oxygen saturation in neonates (venous, arterial, or pulse oximetric). Purpose To validate oxygen saturation displayed on clinical monitors against analyses (with correction for fetal hemoglobin) of blood samples from neonates and to present the oxyhemoglobin dissociation curve for neonates.

METHOD

Seventy-eight neonates, 25 to 38 weeks' gestational age, had 660 arterial and 111 venous blood samples collected for analysis.

RESULTS

The mean difference between oxygen saturation and oxyhemoglobin level was 3% (SD 1.0) in arterial blood and 3% (SD 1.1) in venous blood. The mean difference between arterial oxygen saturation displayed on the monitor and oxyhemoglobin in arterial blood samples was 2% (SD 2.0); between venous oxygen saturation displayed on the monitor and oxyhemoglobin in venous blood samples it was 3% (SD 2.1) and between oxygen saturation as determined by pulse oximetry and oxyhemoglobin in arterial blood samples it was 2.5% (SD 3.1). At a Pao(2) of 50 to 75 mm Hg on the oxyhemoglobin dissociation curve, oxyhemoglobin in arterial blood samples was from 92% to 95%; oxygen saturation was from 95% to 98% in arterial blood samples, from 94% to 97% on the monitor, and from 95% to 97% according to pulse oximetry.

CONCLUSIONS

The safety limits for pulse oximeters are higher and narrower in neonates (95%-97%) than in adults, and clinical guidelines for neonates may require modification.

Umbilical artery catheters in the newborn: effects of position of the catheter tip

BACKGROUND

This section is under preparation and will be included in the next issue.

OBJECTIVES

To determine whether the position of the tip of an umbilical arterial catheter influences the frequency of ischemic events, aortic thrombosis, intraventricular hemorrhage, mortality or necrotising enterocolitis in newborn infants.

SEARCH STRATEGY

Randomized and quasi randomized controlled trials of umbilical catheterization use were obtained from the following sources: 1. Effective Care of the Newborn Infant, edited by JC Sinclair and MB Bracken. 2. Medline Search using Melvyl Medline Plus and the keyword headings 'Umbilic#', 'Catheter#' and subject heading 'Infant, Newborn' 3. Search of personal data files

SELECTION CRITERIA

Randomized trials in newborn infants of any birthweight or gestation. Comparison of high catheter placement with the tip above the diaphragm to a lower position just above the aortic bifurcation. Clinically important end points such as ischemic events or aortic thrombosis.

DATA COLLECTION AND ANALYSIS

Five randomized controlled trials and one alternate assignment study had sufficiently detailed data to allow interpretation.

MAIN RESULTS

High placed umbilical artery catheters are associated with a lower incidence of clinical vascular complications, without an increase in any adverse sequelae. Intraventricular hemorrhage rates, death and necrotising enterocolitis are not more frequent with high compared to low catheters.

REVIEWER'S CONCLUSIONS

There appears to be no evidence to support the use of low placed umbilical artery catheters. High catheters should be used exclusively.