Effects of fentanyl administration on general and cerebral haemodynamics in sick newborn infants

Sedation and anesthesia for imaging of the infant and neonate-a brief review

Sedation and anesthesia are often required in order to facilitate collection of high-quality imaging studies free of significant motion artifact for infants and neonates. Provision of safe sedation and anesthesia requires good communication between the ordering provider, radiologist, and anesthesiologist, careful pre-procedural evaluation of the patient, and availability of appropriate and sufficient equipment, drugs, personnel, and facilities. There are many additional factors to be considered for provision of safe sedation or anesthesia for infants and neonates-it is ideal to involve a fellowship-trained pediatric anesthesiologist in the planning and carry-out of these plans. In this review, we discuss some of the basic definitions of sedation and anesthesia, requirements for safe sedation and anesthesia, and many of the germane risks and additional considerations that factor into the delivery of a safe sedation or anesthesia plan for the imaging of an infant or neonate.

Pharmacologic Analgesia and Sedation in Neonates

Chronic pain and agitation in neonatal life impact the developing brain. Oral sweet-tasting solutions should be used judiciously to mitigate behavioral responses to mild painful procedures, keeping in mind that the long-term impact is unknown. Rapidly acting opioids should be used as part of premedication cocktails for nonemergent endotracheal intubations. Continuous low-dose morphine or dexmedetomidine may be considered for preterm or term neonates exhibiting signs of stress during mechanical ventilation and therapeutic hypothermia, respectively. Further research is required regarding the pharmacokinetics, pharmacodynamics, safety, and efficacy of pharmacologic agents used to mitigate mild, moderate, and chronic pain and stress in neonates.

Diagnostic and predictive value of Doppler ultrasound for evaluation of the brain circulation in preterm infants: a systematic review

INTRODUCTION

Very and extremely preterm infants frequently have brain injury-related long-term neurodevelopmental problems. Altered perfusion, for example, seen in the context of a hemodynamically significant patent ductus arteriosus (PDA), has been linked to injury of the immature brain. However, a direct relation with outcome has not been reviewed systematically.

METHODS

A systematic review was conducted to provide an overview of the value of different cerebral arterial blood flow parameters assessed by Doppler ultrasound, in relation to brain injury, to predict long-term neurodevelopmental outcome in preterm infants.

RESULTS

In total, 23 studies were included. Because of heterogeneity of studies, a meta-analysis of results was not possible. All included studies on resistance index (RI) showed significantly higher values in subjects with a hemodynamically significant PDA. However, absolute differences in RI values were small. Studies using Doppler parameters to predict brain injury and long-term neurodevelopmental outcome were inconsistent.

DISCUSSION

There is no clear evidence to support the routine determination of RI or other Doppler parameters in the cerebral arteries to predict brain injury and long-term neurodevelopmental outcome in the preterm infant. However, there is evidence that elevated RI can point to the presence of a hemodynamically significant PDA.

Clinical pharmacology of fentanyl in preterm infants. A review

Fentanyl is a synthetic opioid that is very important in anesthetic practice because of its relatively short time to peak analgesic effect and the rapid termination of action after small bolus doses. The objective of this survey is to review the clinical pharmacology of fentanyl in preterm infants. The bibliographic search was performed using PubMed and EMBASE databases as search engines. In addition, the books Neofax: A manual of drugs used in neonatal care and Neonatal formulary were consulted. Fentanyl is N-dealkylated by CYP3A4 into the inactive norfentanyl. Fentanyl may be administered as bolus doses or as a continuous infusion. In neonates, there is a remarkable interindividual variability in the kinetic parameters. In neonates, fentanyl half-life ranges from 317 minutes to 1266 minutes and in adults it is 222 minutes. Respiratory depression occurs when fentanyl doses are >5 μg/kg. Chest wall rigidity may occur in neonates and occasionally is associated with laryngospasm. Tolerance to fentanyl may develop after prolonged use of this drug. Significant withdrawal symptoms have been reported in infants treated with continuous infusion for 5 days or longer. Fentanyl is an extremely potent analgesic and is the opioid analgesic most frequently used in the neonatal intensive care unit.

Cerebral blood flow in the neonate

Ensuring adequate oxygenation of the developing brain is the cornerstone of neonatal critical care. Despite decades of clinical research dedicated to this issue of paramount importance, our knowledge and understanding regarding the physiology and pathophysiology of neonatal cerebral blood flow are still rudimentary. This review primarily focuses on currently available human clinical and experimental data on cerebral blood flow and autoregulation in the preterm and term infant. Limitations of systemic blood pressure values as surrogates for monitoring adequate cerebral oxygen delivery are discussed. Particular emphasis is placed on the high interindividual variability in cerebral blood flow values, vasoreactivity, and autoregulatory thresholds making the applications of normative values highly questionable. Technical and ethical difficulties to conduct such trials leave us with a near complete lack of knowledge on how pharmacological and surgical interventions impact on cerebral autoregulation. The ensemble of these works argues for the necessity of highly individualized care by taking advantage of continuous bedside monitoring of cerebral circulation. They also point to the urgent need for further studies addressing the exciting but difficult issue of cerebral blood flow autoregulation in the neonate.

Premedication for neonatal endotracheal intubation: results from the epidemiology of procedural pain in neonates study

OBJECTIVES

To describe the frequency and nature of premedications used prior to neonatal endotracheal intubation; to confront observed practice with current recommendations; and to identify risk factors for the absence of premedication.

DESIGN, SETTING, AND PATIENTS

Data concerning intubations were collected prospectively at the bedside as part of an observational study collecting around-the-clock data on all painful or stressful procedures performed in neonates during the first 14 days of their admission to 13 tertiary care units in the region of Paris, France, between 2005 and 2006.

INTERVENTION

Observational study.

MEASUREMENTS AND MAIN RESULTS

Specific premedication prior to endotracheal intubation was assessed. Ninety one intubations carried out on the same number of patients were analyzed. The specific premedication rate was 56% and included mostly opioids (67%) and midazolam (53%). Compared with recent guidance from the American Academy of Pediatrics, used premedications could be classified as "preferred" (12%), "acceptable" (18%), "not recommended" (27%), and "not described" (43%). In univariate analysis, infants without a specific premedication compared with others were younger at the time of intubation (median age: 0.7 vs. 2.0 days), displayed significantly more frequent spontaneous breathing at the time of intubation (31% vs. 12%) and a higher percentage of analgesia for all other painful procedures (median values: 16% vs. 6%). In multivariate analysis, no factor remained statistically significant.

CONCLUSIONS

Premedication use prior to neonatal intubation was not systematically used and when used it was most frequently inconsistent with recent recommendations. No patient- or center-related independent risk factor for the absence of premedication was identified in this study.

Sedation and analgesia in mechanically ventilated preterm neonates: continue standard of care or experiment?

Attention to comfort and pain control are essential components of neonatal intensive care. Preterm neonates are uniquely susceptible to pain and agitation, and these exposures have a negative impact on brain development. In preterm neonates, chronic pain and agitation are common adverse effects of mechanical ventilation, and opiates or benzodiazepines are the pharmacologic agents most often used for treatment. Questions remain regarding the efficacy, safety, and neurodevelopmental impact of these therapies. Both preclinical and clinical data suggest troubling adverse drug reactions and the potential for adverse longterm neurodevelopmental impact. The negative impacts of standard pharmacologic agents suggest that alternative agents should be investigated. Dexmedetomidine is a promising alternative therapy that requires further interprofessional and multidisciplinary research in this population.

Cerebral autoregulation in neonates with a hemodynamically significant patent ductus arteriosus

OBJECTIVE

Very low birth weight (VLBW) preterm infants are at risk for impaired cerebral autoregulation with pressure passive blood flow. Fluctuations in cerebral perfusion may occur in infants with a hemodynamically significant patent ductus arteriosus (hsPDA), especially during ductal closure. Our goal was to compare cerebral autoregulation using near-infrared spectroscopy in VLBW infants treated for an hsPDA.

STUDY DESIGN

This prospective observational study enrolled 28 VLBW infants with an hsPDA diagnosed by echocardiography and 12 control VLBW infants without an hsPDA. Near-infrared spectroscopy cerebral monitoring was applied during conservative treatment, indomethacin treatment, or surgical ligation. A cerebral pressure passivity index (PPI) was calculated, and PPI differences were compared using a mixed-effects regression model. Cranial ultrasound and magnetic resonance imaging data were also assessed.

RESULTS

Infants with surgically ligated hsPDAs were more likely to have had a greater PPI within 2 hours following ligation than were those treated with conservative management (P=.04) or indomethacin (P=.0007). These differences resolved by 6 hours after treatment.

CONCLUSIONS

Cerebral autoregulation was better preserved after indomethacin treatment of an hsPDA compared with surgical ligation. Infants requiring surgical hsPDA ligation may be at increased risk for cerebral pressure passivity in the 6 hours following surgery.

Cerebral oxygenation during different treatment strategies for a patent ductus arteriosus

BACKGROUND

Preterm infants with a hemodynamically significant patent ductus arteriosus (hsPDA) are at risk for fluctuations in cerebral blood flow, but it is unclear how different hsPDA treatment strategies may affect cerebral oxygenation.

OBJECTIVE

To compare regional cerebral oxygen saturation (rSO(2)) as measured by near-infrared spectroscopy (NIRS) in very low birth weight (VLBW) infants with a hsPDA treated with conservative management, indomethacin, or surgical ligation.

METHODS

This prospective observational study enrolled 33 VLBW infants with a hsPDA diagnosed by echocardiogram and 12 control VLBW infants without a hsPDA. Infants had NIRS cerebral monitoring applied prior to conservative treatment, indomethacin, or surgical ligation. Cranial ultrasound and magnetic resonance imaging data were also collected.

RESULTS

Infants undergoing surgical ligation had a greater time period with >20% change in rSO(2) from baseline (30%) compared to those receiving indomethacin (7.4%, p = 0.001) or control infants without a hsPDA (2.6%, p = 0.0004). NIRS measures were not associated with abnormal neuroimaging in this small cohort.

CONCLUSION

These findings suggest that infants requiring surgical ligation for a hsPDA are at high risk for significant changes in cerebral oxygenation, whereas those receiving either indomethacin or conservative management maintain relatively stable cerebral oxygenation levels. Additional research is necessary to determine if NIRS monitoring identifies infants with a hsPDA at highest risk for brain injury.

Premedication for nonemergency endotracheal intubation in the neonate

Endotracheal intubation is a common procedure in newborn care. The purpose of this clinical report is to review currently available evidence on use of premedication for intubation, identify gaps in knowledge, and provide guidance for making decisions about the use of premedication.

Use of analgesic and sedative drugs in the NICU: integrating clinical trials and laboratory data

Recent advances in neonatal intensive care include and are partly attributable to growing attention for comfort and pain control in the term and preterm infant requiring intensive care.Limitation of painful procedures is certainly possible, but most critically ill infants require unavoidable painful or stressful procedures such as intubation, mechanical ventilation, or catheterization.Many analgesics (opioids and nonsteroidal anti-inflammatory drugs)and sedatives (benzodiazepines and other anesthetic agents) are available but their use varies considerably among units. This review summarizes current experimental knowledge on the effects of sedative and analgesic drugs on brain development and reviews clinical evidence that speaks for or against the use of common analgesic and sedative drugs in the NICU but avoids any discussion of anesthesia during surgery. Risk/benefit ratios of intermittent boluses or continuous infusions for the commonly used sedative and analgesic agents are discussed in the light of clinical and experimental studies. The limitations of extrapolating experimental results from animals to humans must be considered while making practical recommendations based on the currently available evidence.

Ventilation and Haemodynamic Indicators in Spontaneously Breathing Pigs under General Anaesthesia

The aim of this study was to obtain ventilation and haemodynamic data of healthy piglets under general anaesthesia for future patho-physiological experimental studies. A total of 34 domestic piglets of the Czech Black Pied (Přeštice) breed were used in the study. The animals (male to female ratio 8 : 9) were six weeks old and their average body mass was 22 kg. A general anaesthetic (fentanyl and azaperon) was introduced via a pulmonary artery catheter and the spontaneously breathing animals were monitored for 60 min. Cardiac output and haemodynamic indicators were established using intermittent pulmonary artery thermodilution. Blood gas data were deduced using fan dynamic parameters of ventilation and ventilation indices. The study yielded reliable data of dynamic lung indicators (p < 0.05); e.g. the tidal volume 6.00 ± 0.82 ml/kg, hypoxemic index 350.47 ± 42.50 mmHg, lung compliance 0.63 ± 0.12 ml/cmH2O/kg, and haemodynamic indicators (p < 0.01) such as cardiac output 2.12 ± 0.75 l/min, pulmonary vascular resistance 3.92 ± 0.52 and systemic vascular resistance 15.8 ± 6.81 Woods units. Reliable data regarding lung dynamics, cardiac output, preload and afterload of both heart ventricles in spontaneously breathing healthy piglets under general anaesthesia were achieved.

Surgical closure of the patent ductus arteriosus and its effect on the cerebral tissue oxygenation

AIM

Surgical patent ductus arteriosus (PDA) ligation is considered after failure or contraindication of medical treatment. Till now ligation of the PDA has been associated with low morbidity and mortality although recently concerns have been raised about the possible association of ductal clipping and neurodevelopmental abnormalities later in life. By means of near-infrared spectroscopy (NIRS), we analysed the changes in the cerebral tissue oxygenation index (TOI) and fractional tissue oxygen extraction (FTOE) at the time of clipping as well as after clipping.

METHOD

Ten preterm infants with a symptomatic PDA who underwent surgical ligation were continuously monitored for heart rate (HR), mean arterial blood pressure (MABP), peripheral oxygen saturation (SaO(2)) and TOI from 1 h before up to 1 h after clipping. FTOE and haemoglobin difference (HbD) were calculated. Changes in parameters at 5 min after ligation represent the effect of the clipping itself whereas changes up to 1 h-post-clipping represent the post-clipping effect.

RESULTS

At the exact time of clipping, over the entire group, we found a significant increase in TOI of 2.9% (p = 0.037), in HbD of 12.5 micromol/l (p = 0.047) and in HR of 6.5 bpm (p = 0.012). FTOE significantly decreased by 0.02% (p = 0.013). One hour post-clipping, the cerebral and peripheral parameters were not significantly different from the control values before clipping.

CONCLUSION

The ductal clipping in se has no negative effect on the cerebral oxygenation.

Pharmacological therapy for analgesia and sedation in the newborn

Rapid advances have been made in the use of pharmacological analgesia and sedation for newborns requiring neonatal intensive care. Practical considerations for the use of systemic analgesics (opioids, non-steroidal anti-inflammatory agents, other drugs), local and topical anaesthetics, and sedative or anaesthetic agents (benzodiazepines, barbiturates, other drugs) are summarised using an evidence-based medicine approach, while avoiding mention of the underlying basic physiology or pharmacology. These developments have inspired more humane approaches to neonatal intensive care. Despite these advances, little is known about the clinical effectiveness, immediate toxicity, effects on special patient populations, or long-term effects after neonatal exposure to analgesics or sedatives. The desired or adverse effects of drug combinations, interactions with non-pharmacological interventions or use for specific conditions also remain unknown. Despite the huge gaps in our knowledge, preliminary evidence for the use of neonatal analgesia and sedation is available, but must be combined with a clear definition of clinical goals, continuous physiological monitoring, evaluation of side effects or tolerance, and consideration of long-term clinical outcomes.

Analgesia and sedation during mechanical ventilation in neonates

BACKGROUND

Endotracheal intubation and mechanical ventilation are major components of routine intensive care for very low birth weight newborns and sick full-term newborns. These procedures are associated with physiologic, biochemical, and clinical responses indicating pain and stress in the newborn. Most neonates receive some form of analgesia and sedation during mechanical ventilation, although there are marked variations in clinical practice. Clinical guidelines for pharmacologic analgesia and sedation in newborns based on robust scientific data are lacking, as are measures of clinical efficacy.

OBJECTIVE

This article represents a preliminary attempt to develop a scientific rationale for analgesia sedation in mechanically ventilated newborns based on a systematic analysis of published clinical trials.

METHODS

The current literature was reviewed with regard to the use of opioids (fentanyl, morphine, diamorphine), sedative-hypnotics (midazolam), nonsteroidal anti-inflammatory drugs (ibuprofen, indomethacin), and acetaminophen in ventilated neonates. Original meta-analyses were conducted that collated the data from randomized clinical comparisons of morphine or fentanyl with placebo, or morphine with fentanyl.

RESULTS

The results of randomized trials comparing fentanyl, morphine, or midazolam with placebo, and fentanyl with morphine were inconclusive because of small sample sizes. Meta-analyses of the randomized controlled trials indicated that morphine and fentanyl can reduce behavioral and physiologic measures of pain and stress in mechanically ventilated preterm neonates but may prolong the duration of ventilation or produce other adverse effects. Randomized trials of midazolam compared with placebo reported significant adverse effects (P < 0.05) and no apparent clinical benefit; the findings of a meta-analysis suggest that there are insufficient data to justify use of IV midazolam for sedation in ventilated neonates.

CONCLUSIONS

Despite ongoing research in this area, huge gaps in our knowledge remain. Well-designed and adequately powered clinical trials are needed to establish the safety, efficacy, and short- and long-term outcomes of analgesia and sedation in the mechanically ventilated newborn.

[Massive fetomaternal transfusion after induction of labor by oxytocin]

Severe fetomaternal transfusions are seldom, but may lead to neonatal morbidity or death.

CASE REPORT

We report a case of lethal fetomaternal transfusion in which a failure to induce labour, at term, can be suspected.

COMMENTS

We emphasize the need of a close monitoring of the fetal well-being in cases of failed induced labour at term.