The effect of pethidine on the neonatal EEG

The power of N-PASS, aEEG, and BIS in detecting different levels of sedation in neonates: A preliminary study

BACKGROUND

Sedatives are essential drugs in every intensive care unit in order to ensure the patient's optimal level of comfort. Avoiding conditions of over- and under-sedation is a challenge in a neonatal intensive care setting. Drug administration could be optimized by the concomitant use of objective methods to assess the level of sedation.

AIMS

We aimed to look at the ability of different methods (Neonatal Pain, Agitation and Sedation Scale, amplitude-integrated Electroencephalogram, and Bispectral Index), and their combination, in detecting different level of sedation.

METHODS

Twenty-seven neonates among whom 17 were receiving sedatives with or without opiate analgesics were monitored using the Neonatal Pain, Agitation and Sedation Scale, the amplitude-integrated Electroencephalogram, and the Bispectral Index. According to the expert opinion of two trained neonatologists, patients were categorized into three groups: no, light, and deep sedation. Four hours of simultaneous assessment of the Neonatal Pain, Agitation and Sedation Scale scores, Burdjalov scores (to summarize the amplitude-integrated Electroencephalogram trace), and Bispectral Index values were considered for the comparative analysis across these groups.

RESULTS

All three methods could differentiate patients who were not sedated from those who were deeply sedated: median score 12 and 9, respectively, (95% CI of difference = 1.99-5.99, P = 0.001) for the amplitude-integrated Electroencephalogram Burdjalov score; median 1 and -5, respectively, (95% CI of difference = 2.99-8.00, P = 0.001) for the Neonatal Pain, Agitation and Sedation Scale; and median 48 and 37, respectively, (CI of difference = 1.77-22.00, P = 0.043) for the Bispectral Index. However none of them, used alone, was able to differentiate light and deep sedation: median score 10 and 9, respectively, for the amplitude-integrated Electroencephalogram Burdjalov score; median -2 and -5, respectively, for the Neonatal Pain, Agitation and Sedation Scale; and median 48 and 37, respectively, for the Bispectral Index. Only the amplitude-integrated Electroencephalogram and the Neonatal Pain, Agitation and Sedation Scale were able to differentiate between the conditions of no sedation and light sedation. Also, according to the area under the curves values, the combination of the Neonatal Pain, Agitation and Sedation Scale with the Burdjalov score derived from the amplitude-integrated Electroencephalogram showed the best accuracy in differentiating light and deep sedation.

CONCLUSION

While none of the three methods alone was able to precisely differentiate between different levels of sedation, we suggest that using a combination of amplitude-integrated Electroencephalogram and Neonatal Pain, Agitation and Sedation Scale can be useful to distinguish between light and deep sedation in neonatal patients.

Treatment Effects on Neonatal EEG

Conventional EEG and amplitude-integrated electroencephalography are used in neonates to assess prognosis and significant changes in brain activity. Neuroactive medications and hypothermia can influence brain activity and therefore alter EEG interpretation. There are limited studies on the effect of these therapies on neonatal EEG background activity. Medication effects on the EEG or amplitude-integrated electroencephalography include increased interburst interval duration, voltage suppression, and sleep disruption. The effect is transient in term newborns but can be persistent in premature newborns. Although therapeutic hypothermia does not produce significant changes in EEG activity, it does change the time point at which EEG can accurately predict neurodevelopmental outcome. It is important to account for these effects on the EEG to avoid inaccurate interpretation that may affect prognostication.

Drug effects on endogenous brain activity in preterm babies

BACKGROUND

Animal experiments have suggested that the quality of the early intermittent brain activity is important for shaping neuronal connectivity during developmental phase that corresponds to early prematurity. This is a pilot study aiming to assess whether spontaneous activity transients (SAT) in the early preterm babies are affected by drugs that are routinely used in neonatal intensive care.

METHODS

We collected retrospectively seventeen EEG recordings (15 babies, conceptional age 26-33weeks, no brain lesions) that were divided into groups according to drug administration at the time of EEG: phenobarbital, fentanyl, theophylline, and controls. SATs were extracted from the EEG for further analysis with several advanced time-series analysis paradigms.

RESULTS

The visual appearance of SATs was unaffected by drugs. Phenobarbital reduced the total power of the SAT events. Both fentanyl and phenobarbital reduced the length of SATs, and enhanced the oscillations at higher frequencies. Theophylline reduced the oscillatory activity at middle frequencies during SAT, but enhanced oscillations at higher frequencies during time-period prior to SAT.

CONCLUSIONS

Our findings suggest, that (i) all drugs examined affect brain activity in ways that are not seen in the visual EEG interpretation, and that (ii) both acute and long term (i.e. developmental) effects of these drugs on brain may warrant more attention as a part of optimizing preterm neurological care.

Effects of morphine and midazolam on sleep-wake cycling in amplitude-integrated electroencephalography in post-surgical neonates ≥ 32 weeks of gestational age

BACKGROUND

Studies of children who undergo major non-cardiac surgery in the neonatal period are needed so that subsequent abnormal neurodevelopment can be better understood.

OBJECTIVE

It was the aim of our study to describe the influence of analgesic and sedative medication on the predominant background pattern and the development of sleep-wake cycling (SWC), as measured on amplitude-integrated electroencephalography (aEEG), in newborn infants born ≥ 32 weeks' gestation after major non-cardiac surgery.

METHODS

This prospective study included infants ≥ 32(+0) weeks' gestation admitted to the Neonatal Intensive Care Unit at The Royal Children's Hospital in Melbourne who were undergoing major non-cardiac surgery. Data on morphine and midazolam given after surgery were recorded and the BrainZ Monitor was applied post-operatively. The maximum levels of morphine and midazolam were assessed as predictors of time to aEEG outcomes using linear regression.

RESULTS

Forty-seven eligible infants were included. Emergence of SWC was observed at a mean of 13 h after surgery. The maximum dose of morphine or midazolam was not predictive of time to either any or developed SWC.

CONCLUSIONS

Despite high doses of morphine and midazolam, SWC was observed on aEEG in neonates ≥ 32 weeks' gestational age soon after major non-cardiac surgery. The aEEG background pattern was not affected by the maximum dose of either morphine or midazolam.

Changing mechanisms of opiate tolerance and withdrawal during early development: animal models of the human experience

Human infants may be exposed to opiates through placental transfer from an opiate-using mother or through the direct administration of such drugs to relieve pain (e.g., due to illness or neonatal surgery). Infants of many species show physical dependence and tolerance to opiates. The magnitude of tolerance and the nature of withdrawal differ from those of the adult. Moreover, the mechanisms that contribute to the chronic effects of opiates are not well understood in the infant but include biological processes that are both common to and distinct from those of the adult. We review the animal research literature on the effects of chronic and acute opiate exposure in infants and identify mechanisms of withdrawal and tolerance that are similar to and different from those understood in adults. These mechanisms include opioid pharmacology, underlying neural substrates, and the involvement of other neurotransmitter systems. It appears that brain circuitry and opioid receptor types are similar but that NMDA receptor function is immature in the infant. Intracellular signaling cascades may differ but data are complicated by differences between the effects of chronic versus acute morphine treatment. Given the limited treatment options for the dependent infant patient, further study of the biological functions that are altered by chronic opiate treatment is necessary to guide evidenced-based treatment modalities.

Tolerance and withdrawal from prolonged opioid use in critically ill children

OBJECTIVE

After prolonged opioid exposure, children develop opioid-induced hyperalgesia, tolerance, and withdrawal. Strategies for prevention and management should be based on the mechanisms of opioid tolerance and withdrawal.

PATIENTS AND METHODS

Relevant manuscripts published in the English language were searched in Medline by using search terms "opioid," "opiate," "sedation," "analgesia," "child," "infant-newborn," "tolerance," "dependency," "withdrawal," "analgesic," "receptor," and "individual opioid drugs." Clinical and preclinical studies were reviewed for data synthesis.

RESULTS

Mechanisms of opioid-induced hyperalgesia and tolerance suggest important drug- and patient-related risk factors that lead to tolerance and withdrawal. Opioid tolerance occurs earlier in the younger age groups, develops commonly during critical illness, and results more frequently from prolonged intravenous infusions of short-acting opioids. Treatment options include slowly tapering opioid doses, switching to longer-acting opioids, or specifically treating the symptoms of opioid withdrawal. Novel therapies may also include blocking the mechanisms of opioid tolerance, which would enhance the safety and effectiveness of opioid analgesia.

CONCLUSIONS

Opioid tolerance and withdrawal occur frequently in critically ill children. Novel insights into opioid receptor physiology and cellular biochemical changes will inform scientific approaches for the use of opioid analgesia and the prevention of opioid tolerance and withdrawal.

Amplitude-integrated electroencephalographic changes in a newborn induced by overdose of morphine and corrected with naloxone

The amplitude-integrated electroencephalogram (aEEG) is a useful tool to assess brain function after perinatal asphyxia in term infants. We report a full-term newborn with moderate perinatal asphyxia, who accidentally received an overdose of morphine (5000 microg/kg). The overdose of morphine resulted in a clear and immediate change of aEEG background activity from a continuous (C) to discontinuous (DC) background pattern. After administration of naloxone, the background activity restored immediately to continuous background pattern. The aEEG was used to monitor the stepwise reduction in continuous naloxone infusion.

CONCLUSION

An overdose of morphine leads to clear and immediate changes in aEEG which restore after naloxone treatment. The aEEG can be used to monitor naloxone infusion.

[Pathological patterns in neonatal EEG before 30 weeks of gestational age]

Pathological features on very premature EEG concern background abnormalities and abnormal patterns. Positive rolandic sharp waves keep an important place regarding diagnosis and prognosis. Background abnormalities give essential complementary informations. Unusual patterns (abnormal localisation or morphological aspect, high amplitude) remain early markers of cerebral lesions. Analysis of these pathological features must always take into account treatment given to the baby, which can by itself modify the EEG.

Effects of sufentanil on electroencephalogram in very and extremely preterm neonates

OBJECTIVE

The electroencephalogram (EEG) is used in neonatal intensive care units to assess brain maturation and neurologic prognosis in preterm newborns. Most of these newborns are sedated by opioids because of long-term assisted ventilation. The aim of this study was to describe the effects of sufentanil on the EEG in preterm newborns and to evaluate the consequences of such a treatment on neurologic assessment.

METHODS

Fifteen preterm newborns <28 days of extrauterine life were studied. All of them were sedated by sufentanil (initial bolus injection of 0.5 micro g/kg, followed by continuous infusion of 0.2 micro g/kg/h). Three EEGs were performed: the first before and during the bolus injection, the second in the 48 hours after the start of the continuous infusion, and the third at least 24 hours after the treatment was stopped. Qualitative and quantitative methods were used to analyze each EEG.

RESULTS

EEG patterns were not affected by sufentanil treatment. Bolus injection and continuous infusion induced a significant increase of EEG discontinuity in preterm newborns affecting mean burst percentage and mean and maximum interburst duration.

CONCLUSIONS

The present data demonstrate that EEG is affected by bolus injection and continuous infusion of sufentanil. Sedation must therefore be considered to avoid misinterpretation of EEGs.

Effects of morphine on the electroencephalograms of neonates: a prospective, observational study

OBJECTIVES

Although opiates have been reported to profoundly alter the EEG and cause seizures in full-term and premature newborn babies, no prospective study has systematically studied the effects of morphine on the EEG of normal neonates.

METHODS

A prospective observational study was conducted on 20 neurologically and metabolically normal newborn babies of > or =26 weeks post-conceptional age, with EEG recordings performed while on and off morphine infusions.

RESULTS

The recordings performed while the babies were on morphine were all abnormal; the principal abnormalities consisted of prolonged periods of electrical quiescence (PPEQs) and excessive interictal epileptiform activity. After the morphine was discontinued, the PPEQs resolved and the EEG background rhythms were normal for age, but 5 continued to have excessive sharp transients. All babies did well clinically and did not require anti-epileptic drug therapy.

CONCLUSIONS

Morphine produces a profound, largely reversible alteration of all neonatal EEGs at various post-conceptional ages. The study has implications for caution in formulating conclusions regarding the clinical significance of EEGs of critically ill neonates on morphine infusions.

Health professional perceptions of opioid dependence among patients with pain

The purpose of this study was to determine the percentage of patients perceived by health professionals to be opioid dependent among all patients presenting with pain and specifically among sickle cell patients with pain. Surveys were completed by all staff, residents, and nurses at an urban teaching hospital with an emergency department population consisting primarily of lower socioeconomic patients of African-American origin. The surveys requested a percentage estimate of all pain patients and sickle cell patients with pain presenting to this hospital who they perceived to be opioid dependent. The estimated percentage of opioid dependent patients presenting to the emergency department with pain was 4% for staff (P < .05, n = 14), 9% for residents (n = 31), and 7% for nurses (n = 41), and the estimates for sickle cell patients presenting with pain only were 8%, 17%, and 13% respectively (P < .05). All health professional groups surveyed estimated opioid dependence in patients with pain far in excess of that shown in previous studies. It is unknown whether pain medication are withheld inappropriately by physicians who perceived patients with pain to be opioid dependent, and that this deserved further study especially among sickle cell patients.

Prognostic value of continuous electroencephalographic recording in full term infants with hypoxic ischaemic encephalopathy

The prognostic value of early neonatal continuous electroencephalographic recordings in hypoxic ischaemic encephalopathy was evaluated. Thirty seven full term infants with hypoxic ischaemic encephalopathy were studied. The electroencephalogram (EEG) was recorded using four or eight channel Oxford Medilog recorders and was started as soon as possible after birth. The recordings were initially visually analysed and divided into four categories: three in relation to the grade of discontinuity of the background activity (continuous, discontinuous, and maximum depression) and an additional fourth category to include status epilepticus. The EEGs with discontinuous activity were then analysed by computer to obtain a more objective assessment of discontinuity. The results were related to neurological outcome. Continuous background activity was associated with a normal outcome in all but the three infants who had continuous, but asymmetrical EEGs and who developed contralateral hemiplegia. In the eight infants with discontinuous activity, the outcome appeared to be related to the grade of continuity and the presence of clear convulsions on the EEG. The 10 infants with maximum depression and status epilepticus had severe impairment. These preliminary results suggest that continuous recording of EEGs could be used routinely in term infants with hypoxic ischaemic encephalopathy. Computer analysis can improve the value of this technique, allowing the identification of infants who might benefit from early therapeutic intervention.

Neurological findings in newborn infants after extracorporeal membrane oxygenation, with special reference to the EEG

Seventeen newborn infants were treated with extracorporeal membrane oxygenation (ECMO). Two died shortly after the start of ECMO due to the underlying disease, two died later in the course due to a lack of recovery of lung function and two others died weeks after ECMO from renal damage and a cardiac defect. Of the survivors, nine are developing normally (aged between one and four years) and two are severely disabled because of infarctions of the left hemisphere, acquired before and after ECMO. Intermittent-discontinuous EEGs did not indicate a poor prognosis if normalization of the EEG occurred within seven days. However, infarcted areas on ultrasonography, persistent EEG changes or deteriorating findings indicated disability or early death.