Plasma beta-endorphin concentrations and analgesia-muscle relaxation in the newborn infant supported by mechanical ventilation

Biomarkers for assessing pain and pain relief in the neonatal intensive care unit

Newborns admitted to the neonatal intensive care unit (NICU) regularly undergo painful procedures and may face various painful conditions such as postoperative pain. Optimal management of pain in these vulnerable preterm and term born neonates is crucial to ensure their comfort and prevent negative consequences of neonatal pain. This entails accurate and timely identification of pain, non-pharmacological pain treatment and if needed administration of analgesic therapy, evaluation of treatment effectiveness, and monitoring of adverse effects. Despite the widely recognized importance of pain management, pain assessment in neonates has thus far proven to be a challenge. As self-report, the gold standard for pain assessment, is not possible in neonates, other methods are needed. Several observational pain scales have been developed, but these often rely on snapshot and largely subjective observations and may fail to capture pain in certain conditions. Incorporation of biomarkers alongside observational pain scores holds promise in enhancing pain assessment and, by extension, optimizing pain treatment and neonatal outcomes. This review explores the possibilities of integrating biomarkers in pain assessment in the NICU.

Pharmacological pain and sedation interventions for the prevention of intraventricular hemorrhage in preterm infants on assisted ventilation - an overview of systematic reviews

BACKGROUND

Germinal matrix hemorrhage and intraventricular hemorrhage (GMH-IVH) may contribute to neonatal morbidity and mortality and result in long-term neurodevelopmental sequelae. Appropriate pain and sedation management in ventilated preterm infants may decrease the risk of GMH-IVH; however, it might be associated with harms.

OBJECTIVES

To summarize the evidence from systematic reviews regarding the effects and safety of pharmacological interventions related to pain and sedation management in order to prevent GMH-IVH in ventilated preterm infants.

METHODS

We searched the Cochrane Library August 2022 for reviews on pharmacological interventions for pain and sedation management to prevent GMH-IVH in ventilated preterm infants (< 37 weeks' gestation). We included Cochrane Reviews assessing the following interventions administered within the first week of life: benzodiazepines, paracetamol, opioids, ibuprofen, anesthetics, barbiturates, and antiadrenergics. Primary outcomes were any GMH-IVH (aGMH-IVH), severe IVH (sIVH), all-cause neonatal death (ACND), and major neurodevelopmental disability (MND). We assessed the methodological quality of included reviews using the AMSTAR-2 tool. We used GRADE to assess the certainty of evidence.

MAIN RESULTS

We included seven Cochrane Reviews and one Cochrane Review protocol. The reviews on clonidine and paracetamol did not include randomized controlled trials (RCTs) matching our inclusion criteria. We included 40 RCTs (3791 infants) from reviews on paracetamol for patent ductus arteriosus (3), midazolam (3), phenobarbital (9), opioids (20), and ibuprofen (5). The quality of the included reviews was high. The certainty of the evidence was moderate to very low, because of serious imprecision and study limitations. Germinal matrix hemorrhage-intraventricular hemorrhage (any grade) Compared to placebo or no intervention, the evidence is very uncertain about the effects of paracetamol on aGMH-IVH (risk ratio (RR) 0.89, 95% confidence interval (CI) 0.38 to 2.07; 2 RCTs, 82 infants; very low-certainty evidence); midazolam may result in little to no difference in the incidence of aGMH-IVH (RR 1.68, 95% CI 0.87 to 3.24; 3 RCTs, 122 infants; low-certainty evidence); the evidence is very uncertain about the effect of phenobarbital on aGMH-IVH (RR 0.99, 95% CI 0.83 to 1.19; 9 RCTs, 732 infants; very low-certainty evidence); opioids may result in little to no difference in aGMH-IVH (RR 0.85, 95% CI 0.65 to 1.12; 7 RCTs, 469 infants; low-certainty evidence); ibuprofen likely results in little to no difference in aGMH-IVH (RR 0.99, 95% CI 0.81 to 1.21; 4 RCTs, 759 infants; moderate-certainty evidence). Compared to ibuprofen, the evidence is very uncertain about the effects of paracetamol on aGMH-IVH (RR 1.17, 95% CI 0.31 to 4.34; 1 RCT, 30 infants; very low-certainty evidence). Compared to midazolam, morphine may result in a reduction in aGMH-IVH (RR 0.28, 95% CI 0.09 to 0.87; 1 RCT, 46 infants; low-certainty evidence). Compared to diamorphine, the evidence is very uncertain about the effect of morphine on aGMH-IVH (RR 0.65, 95% CI 0.40 to 1.07; 1 RCT, 88 infants; very low-certainty evidence). Severe intraventricular hemorrhage (grade 3 to 4) Compared to placebo or no intervention, the evidence is very uncertain about the effect of paracetamol on sIVH (RR 1.80, 95% CI 0.43 to 7.49; 2 RCTs, 82 infants; very low-certainty evidence) and of phenobarbital (grade 3 to 4) (RR 0.91, 95% CI 0.66 to 1.25; 9 RCTs, 732 infants; very low-certainty evidence); opioids may result in little to no difference in sIVH (grade 3 to 4) (RR 0.98, 95% CI 0.71 to 1.34; 6 RCTs, 1299 infants; low-certainty evidence); ibuprofen may result in little to no difference in sIVH (grade 3 to 4) (RR 0.82, 95% CI 0.54 to 1.26; 4 RCTs, 747 infants; low-certainty evidence). No studies on midazolam reported this outcome. Compared to ibuprofen, the evidence is very uncertain about the effects of paracetamol on sIVH (RR 2.65, 95% CI 0.12 to 60.21; 1 RCT, 30 infants; very low-certainty evidence). Compared to midazolam, the evidence is very uncertain about the effect of morphine on sIVH (grade 3 to 4) (RR 0.08, 95% CI 0.00 to 1.43; 1 RCT, 46 infants; very low-certainty evidence). Compared to fentanyl, the evidence is very uncertain about the effect of morphine on sIVH (grade 3 to 4) (RR 0.59, 95% CI 0.18 to 1.95; 1 RCT, 163 infants; very low-certainty evidence). All-cause neonatal death Compared to placebo or no intervention, the evidence is very uncertain about the effect of phenobarbital on ACND (RR 0.94, 95% CI 0.51 to 1.72; 3 RCTs, 203 infants; very low-certainty evidence); opioids likely result in little to no difference in ACND (RR 1.12, 95% CI 0.80 to 1.55; 5 RCTs, 1189 infants; moderate-certainty evidence); the evidence is very uncertain about the effect of ibuprofen on ACND (RR 1.00, 95% CI 0.38 to 2.64; 2 RCTs, 112 infants; very low-certainty evidence). Compared to midazolam, the evidence is very uncertain about the effect of morphine on ACND (RR 0.31, 95% CI 0.01 to 7.16; 1 RCT, 46 infants; very low-certainty evidence). Compared to diamorphine, the evidence is very uncertain about the effect of morphine on ACND (RR 1.17, 95% CI 0.43 to 3.19; 1 RCT, 88 infants; very low-certainty evidence). Major neurodevelopmental disability Compared to placebo, the evidence is very uncertain about the effect of opioids on MND at 18 to 24 months (RR 2.00, 95% CI 0.39 to 10.29; 1 RCT, 78 infants; very low-certainty evidence) and at five to six years (RR 1.6, 95% CI 0.56 to 4.56; 1 RCT, 95 infants; very low-certainty evidence). No studies on other drugs reported this outcome.

AUTHORS' CONCLUSIONS

None of the reported studies had an impact on aGMH-IVH, sIVH, ACND, or MND. The certainty of the evidence ranged from moderate to very low. Large RCTs of rigorous methodology are needed to achieve an optimal information size to assess the effects of pharmacological interventions for pain and sedation management for the prevention of GMH-IVH and mortality in preterm infants. Studies might compare interventions against either placebo or other drugs. Reporting of the outcome data should include the assessment of GMH-IVH and long-term neurodevelopment.

Opioids for newborn infants receiving mechanical ventilation

BACKGROUND

Mechanical ventilation is a potentially painful and discomforting intervention that is widely used in neonatal intensive care. Newborn infants demonstrate increased sensitivity to pain, which may affect clinical and neurodevelopmental outcomes. The use of drugs that reduce pain might be important in improving survival and neurodevelopmental outcomes.

OBJECTIVES

To determine the benefits and harms of opioid analgesics for neonates (term or preterm) receiving mechanical ventilation compared to placebo or no drug, other opioids, or other analgesics or sedatives.

SEARCH METHODS

We used the standard search strategy of Cochrane Neonatal to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2020, Issue 9), in the Cochrane Library; MEDLINE via PubMed (1966 to 29 September 2020); Embase (1980 to 29 September 2020); and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) (1982 to 29 September 2020). We searched clinical trials databases, conference proceedings, and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled trials comparing opioids to placebo or no drug, to other opioids, or to other analgesics or sedatives in newborn infants on mechanical ventilation. We excluded cross-over trials. We included term (≥ 37 weeks' gestational age) and preterm (< 37 weeks' gestational age) newborn infants on mechanical ventilation. We included any duration of drug treatment and any dosage given continuously or as bolus; we excluded studies that gave opioids to ventilated infants for procedures.

DATA COLLECTION AND ANALYSIS

For each of the included trials, we independently extracted data (e.g. number of participants, birth weight, gestational age, types of opioids) using Cochrane Effective Practice and Organisation of Care Group (EPOC) criteria and assessed the risk of bias (e.g. adequacy of randomisation, blinding, completeness of follow-up). We evaluated treatment effects using a fixed-effect model with risk ratio (RR) for categorical data and mean difference (MD) for continuous data. We used the GRADE approach to assess the certainty of evidence.

MAIN RESULTS

We included 23 studies (enrolling 2023 infants) published between 1992 and 2019. Fifteen studies (1632 infants) compared the use of morphine or fentanyl versus placebo or no intervention. Four studies included both term and preterm infants, and one study only term infants; all other studies included only preterm infants, with five studies including only very preterm infants. We are uncertain whether opioids have an effect on the Premature Infant Pain Profile (PIPP) Scale in the first 12 hours after infusion (MD -5.74, 95% confidence interval (CI) -6.88 to -4.59; 50 participants, 2 studies) and between 12 and 48 hours after infusion (MD -0.98, 95% CI -1.35 to -0.61; 963 participants, 3 studies) because of limitations in study design, high heterogeneity (inconsistency), and imprecision of estimates (very low-certainty evidence - GRADE). The use of morphine or fentanyl probably has little or no effect in reducing duration of mechanical ventilation (MD 0.23 days, 95% CI -0.38 to 0.83; 1259 participants, 7 studies; moderate-certainty evidence because of unclear risk of bias in most studies) and neonatal mortality (RR 1.12, 95% CI 0.80 to 1.55; 1189 participants, 5 studies; moderate-certainty evidence because of imprecision of estimates). We are uncertain whether opioids have an effect on neurodevelopmental outcomes at 18 to 24 months (RR 2.00, 95% CI 0.39 to 10.29; 78 participants, 1 study; very low-certainty evidence because of serious imprecision of the estimates and indirectness). Limited data were available for the other comparisons (i.e. two studies (54 infants) on morphine versus midazolam, three (222 infants) on morphine versus fentanyl, and one each on morphine versus diamorphine (88 infants), morphine versus remifentanil (20 infants), fentanyl versus sufentanil (20 infants), and fentanyl versus remifentanil (24 infants)). For these comparisons, no meta-analysis was conducted because outcomes were reported by one study.

AUTHORS' CONCLUSIONS

We are uncertain whether opioids have an effect on pain and neurodevelopmental outcomes at 18 to 24 months; the use of morphine or fentanyl probably has little or no effect in reducing the duration of mechanical ventilation and neonatal mortality. Data on the other comparisons planned in this review (opioids versus analgesics; opioids versus other opioids) are extremely limited and do not allow any conclusions. In the absence of firm evidence to support a routine policy, opioids should be used selectively - based on clinical judgement and evaluation of pain indicators - although pain measurement in newborns has limitations.

A Guide to Pain Assessment and Management in the Neonate

Newborn infants experience acute pain with various medical procedures. Evidence demonstrates that controlling pain in the newborn period is beneficial, improving physiologic, behavioral, and hormonal outcomes. Multiple validated scoring systems exist to assess pain in a neonate; however, there is no standardized or universal approach for pain management. Healthcare facilities should establish a neonatal pain control program. The first step is to minimize the total number of painful iatrogenic events when possible. If a procedure cannot be avoided, a tiered approach to manage pain using environmental, non-pharmacologic, and pharmacologic modalities is recommended. This systematic approach should decrease acute neonatal pain, poor outcomes, and provider and parent dissatisfaction.

Pain management in newborns

As a standard of care for preterm/term newborns effective pain management may improve their clinical and neurodevelopmental outcomes. Neonatal pain is assessed using context-specific, validated, and objective pain methods, despite the limitations of currently available tools. Therapeutic approaches reducing invasive procedures and using pharmacologic, behavioral, or environmental measures are used to manage neonatal pain. Nonpharmacologic approaches like kangaroo care, facilitated tucking, non-nutritive sucking, sucrose, and others can be used for procedural pain or adjunctive therapy. Local/topical anesthetics, opioids, NSAIDs/acetaminophen and other sedative/anesthetic agents can be incorporated into NICU protocols for managing moderate/severe pain or distress in all newborns.

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.

Pain control: opioid dosing, population kinetics and side-effects

Neonates undergoing invasive procedures, postoperative pain or ventilatory support commonly receive opioids for treating pain and stress. Randomized clinical trials have examined the benefits and adverse effects of morphine or fentanyl for ventilated neonates and other indications. This paper summarizes the current evidence for opioid dosing in newborns, reviews their side-effects and explains the use of population kinetics and non-linear mixed-effects modeling to analyze the data from clinical trials. Opioid use should be reserved for severe pain postoperatively or during intensive care in neonates, using continuous infusions rather than intermittent boluses. The safety and efficacy data from prolonged opioid use, particularly on the long-term outcomes of neonates, is still lacking. The pharmacodynamics and pharmacogenetics of opioid use in infancy needs further investigation, using non-linear mixed-effects models to drive individualized therapy. The current interest in opioid research will reap rich dividends in providing pain relief for neonates and avoiding dangerous side effects.

Analgesia and local anesthesia during invasive procedures in the neonate

BACKGROUND

Preterm and full-term neonates admitted to the neonatal intensive care unit or elsewhere in the hospital are routinely subjected to invasive procedures that can cause acute pain. Despite published data on the complex behavioral, physiologic, and biochemical responses of these neonates and the detrimental short- and long-term clinical outcomes of exposure to repetitive pain, clinical use of pain-control measures in neonates undergoing invasive procedures remains sporadic and suboptimal. As part of the Newborn Drug Development Initiative, the US Food and Drug Administration and the National Institute of Child Health and Human Development invited a group of international experts to form the Neonatal Pain Control Group to review the therapeutic options for pain management associated with the most commonly performed invasive procedures in neonates and to identify research priorities in this area.

OBJECTIVE

The goal of this article was to review and synthesize the published clinical evidence for the management of pain caused by invasive procedures in preterm and full-term neonates.

METHODS

Clinical studies examining various therapies for procedural pain in neonates were identified by searches of MEDLINE (1980-2004), the Cochrane Controlled Trials Register (The Cochrane Library, Issue 1, 2004), the reference lists of review articles, and personal files. The search terms included specific drug names, infant-newborn, infant-preterm, and pain, using the explode function for each key word. The English-language literature was reviewed, and case reports and small case series were discarded.

RESULTS

The most commonly performed invasive procedures in neonates included heel lancing, venipuncture, IV or arterial cannulation, chest tube placement, tracheal intubation or suctioning, lumbar puncture, circumcision, and SC or IM injection. Various drug classes were examined critically, including opioid analgesics, sedative/hypnotic drugs, nonsteroidal anti-inflammatory drugs and acetaminophen, injectable and topical local anesthetics, and sucrose. Research considerations related to each drug category were identified, potential obstacles to the systematic study of these drugs were discussed, and current gaps in knowledge were enumerated to define future research needs. Discussions relating to the optimal design for and ethical constraints on the study of neonatal pain will be published separately. Well-designed clinical trials investigating currently available and new therapies for acute pain in neonates will provide the scientific framework for effective pain management in neonates undergoing invasive procedures.

Neuromuscular paralysis for newborn infants receiving mechanical ventilation

BACKGROUND

Ventilated newborn infants breathing in asynchrony with the ventilator are at risk for complications during mechanical ventilation, such as pneumothorax or intraventricular hemorrhage, and are exposed to more severe barotrauma, which consequently could impair their clinical outcome. Neuromuscular paralysis, which eliminates spontaneous breathing efforts of the infant, has potential advantages in this respect. However, a number of complications have been reported with muscle relaxation in infants, so that concerns exist regarding the safety of prolonged neuromuscular paralysis in newborn infants.

OBJECTIVES

To determine whether routine neuromuscular paralysis of newborn infants receiving mechanical ventilation compared with no routine paralysis results in clinically important benefits or harms.

SEARCH STRATEGY

The Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 1, 2004), MEDLINE (from 1966 to April 2004) and EMBASE (from 1988 to April 2004) were searched. References of review articles were hand searched. Language restriction was not imposed.

SELECTION CRITERIA

All trials using random or quasi-random patient allocation, in which the routine use of neuromuscular blocking agents during mechanical ventilation was compared to no paralysis or selective paralysis in newborn infants. Methodological quality was assessed blindly and independently by the two authors.

DATA COLLECTION AND ANALYSIS

Data were abstracted using standard methods of the Cochrane Collaboration and its Neonatal Review Group, with independent evaluation of trial quality, and abstraction and synthesis of data by both authors. Treatment effect was analysed using relative risk, risk difference and weighted mean difference.

MAIN RESULTS

Ten possibly eligible trials were identified, of which six were included in the review. All the included trials studied preterm infants ventilated for respiratory distress syndrome, and used pancuronium as the neuromuscular blocking agent. In the analysis of the results of all trials, no significant difference was found in mortality, air leak or chronic lung disease, but there was a significant reduction in intraventricular hemorrhage and a trend towards less severe intraventricular hemorrhages. In the subgroup analysis of trials studying a selected population of ventilated infants with evidence of asynchronous respiratory efforts, a significant reduction in intraventricular hemorrhage (any grade and severe IVH) was found, and a trend towards less air leak. In the subgroup analysis of trials studying an unselected population of ventilated infants, no significant differences were found for any of the outcomes.

AUTHORS' CONCLUSIONS

For ventilated preterm infants with evidence of asynchronous respiratory efforts, neuromuscular paralysis with pancuronium seems to have a favourable effect on intraventricular hemorrhage and possibly on air leak. Uncertainty remains, however, regarding the long term pulmonary and neurologic effects, and regarding the safety of prolonged use of pancuronium in ventilated newborn infants. There is no evidence from randomized trials on the effects of neuromuscular blocking agents other than pancuronium. The routine use of pancuronium or any other neuromuscular blocking agent in ventilated newborn infants cannot be recommended based on current evidence.

Amniotic fluid beta-endorphin: a prognostic marker for gastroschisis?

PURPOSE

The aim of this work was to study amniotic fluid beta-endorphin as a potential predictor for postnatal morbidity in gastroschisis.

METHODS

Beta-endorphin was assayed in 43 amniotic fluid samples from 13 pregnant women with fetal gastroschisis undergoing diagnostic amniocentesis or therapeutic amnioinfusion and compared with 33 controls. Within the gastroschisis group, the authors investigated the relationship between postnatal morbidity and the peak value of amniotic fluid beta-endorphin (AFBE).

RESULTS

Ten AFBE values in 6 cases of gastroschisis were above the upper limit of the 95% confidence interval derived from controls. Postnatal morbidity was significantly higher when peak AFBE exceeded 10 microg/L (n = 4 pregnancies) compared with below 5 microg/L (n = 9 pregnancies), as shown by mean duration of mechanical ventilation (15.2 v 3 days; P =.01), of parenteral feeding (77 v. 18.7 days; P =.04), and of hospitalization (84 v 32.2 days; P =.04). There was no statistically significant association between postnatal morbidity markers and prenatal dilation of fetal bowel.

CONCLUSIONS

The most severe cases of gastroschisis are associated with high levels of AFBE. The authors speculate that this fetal hormonal response could result from stress or pain caused by prenatal bowel damage.

Neuromuscular paralysis for newborn infants receiving mechanical ventilation

BACKGROUND

Ventilated newborn infants breathing in asynchrony with the ventilator are at risk for complications during mechanical ventilation, such as pneumothorax or intraventricular hemorrhage, and are exposed to more severe barotrauma, which consequently could impair their clinical outcome. Neuromuscular paralysis, which eliminates spontaneous breathing efforts of the infant, has potential advantages in this respect. However, a number of complications have been reported with muscle relaxation in infants, so that concerns exist regarding the safety of prolonged neuromuscular paralysis in newborn infants.

OBJECTIVES

To determine whether routine neuromuscular paralysis of newborn infants receiving mechanical ventilation compared with no routine paralysis results in clinically important benefits or harms.

SEARCH STRATEGY

MEDLINE (from 1966 to May 2000) and EMBASE (from 1988 to May 2000) were searched, as well as The Cochrane Controlled Trials Register (issue 2, 2000). References of review articles were hand searched. Language restriction was not imposed.

SELECTION CRITERIA

All trials using random or quasi-random patient allocation, in which the routine use of neuromuscular blocking agents during mechanical ventilation was compared to no paralysis or selective paralysis in newborn infants. Methodological quality was assessed blindly and independently by the two authors.

DATA COLLECTION AND ANALYSIS

Data were abstracted using standard methods of the Cochrane Collaboration and its Neonatal Review Group, with independent evaluation of trial quality, and abstraction and synthesis of data by both authors. Treatment effect was analysed using relative risk, risk difference and weighted mean difference.

MAIN RESULTS

Ten possibly eligible trials were identified, of which five were included in the review. All the included trials studied preterm infants ventilated for respiratory distress syndrome, and used pancuronium as the neuromuscular blocking agent. In the analysis of the results of all trials, no difference was found in mortality, air leak or chronic lung disease, but there was a significant reduction in intraventricular hemorrhage and a trend towards less severe intraventricular hemorrhages. In the subgroup analysis of trials studying a selected population of ventilated infants with evidence of asynchronous respiratory efforts, a significant reduction in intraventricular hemorrhage (any grade and severe IVH) was found, and a trend towards less air leak. In the subgroup analysis of trials studying an unselected population of ventilated infants, no differences were found for any of the outcomes.

REVIEWER'S CONCLUSIONS

For ventilated preterm infants with evidence of asynchronous respiratory efforts, neuromuscular paralysis with pancuronium seems to have a favourable effect on intraventricular hemorrhage and possibly on air leak. Uncertainty remains, however, regarding the long term pulmonary and neurologic effects, and regarding the safety of prolonged use of pancuronium in ventilated newborn infants. There is no evidence from randomized trials on the effects of neuromuscular blocking agents other than pancuronium. Therefore, the routine use of pancuronium or any other neuromuscular blocking agent in ventilated newborn infants cannot be recommended based on current evidence.

Advantages of fentanyl over morphine in analgesia for ventilated newborn infants after birth: A randomized trial

OBJECTIVE

To compare the efficacy and adverse effects of fentanyl or morphine analgesia during the first 2 days of life in newborn infants who underwent mechanical ventilation.

STUDY DESIGN

In a randomized double-blind trial, 163 infants were allocated to receive a continuous infusion of fentanyl (10.5 microg/kg over a 1-hour period followed by 1.5 microg/kg/hr) or morphine (140 microg/kg over a 1-hour period followed by 20 microg/kg/hr) for at least 24 hours. The severity of pain was assessed with physiological parameters, a behavioral pain scale, and stress hormone concentrations before and 2 and 24 hours after the start of treatment.

RESULTS

The analgesic effect was similar in both groups, as judged by the pain scale. Plasma adrenaline and noradrenaline concentrations decreased significantly from 0 to 24 hours in both groups. Median adrenaline decrease was 0.5 nmol/L (interquartile range [IQR] 1.1;0.0) in the fentanyl and 0.7 nmol/L (IQR 1.3;0.1) in the morphine group, noradrenaline 2.1 nmol/L (IQR 9.0;0.2), and 3.0 nmol/L (IQR 7. 5;0.3), respectively. beta-endorphin decreased significantly only in the fentanyl group ( 14 pmol/L (IQR 28; 7), P <.05). Decreased gastrointestinal motility was less frequent in the fentanyl group (23% vs 47%, P <.01).

CONCLUSIONS

With at least as effective analgesia as with morphine, fentanyl had fewer side effects. Fentanyl may be superior to morphine for short-term postnatal analgesia in newborn infants.

Randomised controlled trial of low dose fentanyl infusion in preterm infants with hyaline membrane disease

AIM

To evaluate the effects of low dose fentanyl infusion analgesia on behavioural and neuroendocrine stress response and short term outcome in premature infants ventilated for hyaline membrane disease.

METHODS

Twenty seven ventilated preterm infants were randomly assigned to receive a mean fentanyl infusion of 1.1 (0.08 SE) micrograms/kg/h for 75 (5) hours, and 28 untreated infants were considered a control group. A behavioural sedation score was used to assess the infants' behaviour. Urinary metanephrine and the normetanephrine:creatinine molar ratio were determined at 0, 24, 48 and 72 hours. Outcome data and ventilatory indexes were recorded for each infant.

RESULTS

The fentanyl group showed significantly lower behavioural stress scores and O2 desaturations than controls and lower urinary concentrations of metanephrine and normetanephrine at 24, 48, 72 hours. The two groups showed no significant difference in ventilatory variables or short term outcome.

CONCLUSIONS

A short course of low dose fentanyl infusion reduces behavioural sedation scores, O2 desaturations and neuroendocrine stress response in preterm ventilated infants.

Physiological, hormonal, and behavioral responses to a single fentanyl dose in intubated and ventilated preterm neonates

OBJECTIVE

To study the responses of ventilated preterm neonates to a single dose of opioid.

STUDY DESIGN

In a randomized, double-blind, controlled trial, 22 mechanically ventilated preterm infants (< or = 32 weeks) were observed before medication and at 30 and 60 minutes after administration of fentanyl (3 micrograms/kg) or placebo. Heart rate, blood pressure, arterial blood gases, ventilator settings, and behavioral measures (Neonatal Facial Coding System and Modified Postoperative Comfort Score) were recorded during each period. Blood cortisol, growth hormone, glucose, and lactate were measured before and at 60 minutes after analgesia. Behavioral measures were assessed at the bedside and from video films recorded during each observation period.

RESULTS

Patients presented high basal levels of cortisol, growth hormone, and lactate. Behavioral scales indicated the presence of pain before any medication. In the fentanyl group, the maximum and minimum heart rate decreased and growth hormone level increased after analgesia. At the video analysis of behavioral measures, postoperative comfort score increased and neonatal facial coding system score decreased in the fentanyl group.

CONCLUSION

Single doses of fentanyl analgesia can reduce the physiologic/behavioral measures of pain and stress associated with mechanical ventilation in preterm infants.

The use of intravenous opioids to provide analgesia in critically ill, premature neonates: a research critique

The intravenous (i.v.) administration of opioids to neonates is a common method of providing analgesia in the intensive care setting. This paper reviews and critiques the studies that have investigated this intervention. The studies are grouped into four major areas: pharmacokinetic studies; i.v. opioids for anesthesia; i.v. opioids for sedation or analgesia in mechanically ventilated neonates; and cardiorespiratory effects of i.v. opioids. An attempt is made to synthesize current knowledge about the analgesic effects and side effects associated with the use of i.v. opioids in neonates. The intent is to stimulate additional research on the management of neonatal pain using opioid analgesics.

Alfentanil as procedural pain relief in newborn infants

AIMS

To assess the need for, and the suitability of, alfentanil for pain relief during tracheal suction used in assisted ventilation in newborn infants.

METHODS

In a randomised, controlled, double blind, crossover trial, placebo (10 micrograms/kg) and 20 micrograms/kg alfentanil were infused in random order two minutes before three separate endotracheal suctions, at least six hours apart, to 10 infants. Measurements were made of physiological variables, behaviour, and stress hormones.

RESULTS

After placebo infusion heart rate significantly increased (median 14; interquartile range 12-16 beats/minute) as did behavioural pain score (5; 3-5). Alfentanil (20 micrograms/kg) attenuated the heart rate increase, normalised the pain score, and caused a decrease in plasma adrenaline activity (0.3; 0.2-0.7 nmol/l). Noradrenaline concentration showed a nonsignificant decreasing trend with increasing alfentanil dose and beta endorphin was unchanged. Rigidity was noted in the placebo (n = 2), 10 micrograms/kg (n = 2), and 20 micrograms/kg (n = 5) alfentanil groups, respectively.

CONCLUSIONS

Tracheal suction is a painful procedure. The dose of alfentanil required for pain relief (20 micrograms/kg) causes a high incidence of rigidity and thus should be used only with muscle relaxant.