The introduction of sophisticated techniques and new technologies in neonatal care has resulted in the increased survival of neonates, including those who are very small for gestational age (VSGA). The diagnosis, treatment, and daily nursing care these patients require are clinically challenging.1,2 Electroencephalography (EEG) is a procedure that enables the precise evaluation of the neonate's neurological condition. The technical development of EEG equipment, such as digital signal processing with noise reduction and digital recording of video signals, provides medical professionals with a powerful tool for monitoring the brain. It is particularly useful in neonates with low body weight and those who rarely present with clinical symptoms of brain damage. The principles underlying neonatal EEG are the same as for other age groups. However, there are fundamental differences in the interpretation of the results and the necessary conditions regarding nursing care during the EEG recordings. In this report, the requirements and optimal conditions for conducting neonatal EEG recordings are evaluated and discussed.
Electroencephalography is a noninvasive procedure; therefore, additional consent for an EEG is not required. Nevertheless, it is important to explain the aim and techniques involved in performing an EEG examination to the parents and discuss all of their concerns. This is particularly true, because most parents are not familiar with the procedure and may be apprehensive.3,4Figure 1 shows the standard placement of the electrodes and wires, which parents may find alarming. Discussions with parents regarding the EEG procedure can be held by the physician, the EEG technician, or the nurse. However, as nurses who care for VSGA newborns typically establish long-term relationships with the parents and gain their trust over time, it is advantageous to have the nurse involved in these explanations. Therefore, the nurses' knowledge of this subject is crucial to their ability to responsibly and professionally answer any questions the parents may have.
Equipment and Techniques
The nerve cells of the brain produce very small, fluctuating electrical voltages that are measured in microvolts (μV). An EEG measures the synchronized activity of neurons. The examination is based on recording the difference in the voltage potential between two defined places on the scalp over time. The standard recording speed is 30 mm per second (mm/s), and the sensitivity is 100 μV per 1 cm. According to the international 10-20 system,5 the following electrode placement is recommended: F1, T3, C3, and O1 on the left side of the skull; F2, T4, C4, and O2 on the right side; and Cz in the midline. The reduced number of electrodes (9 active electrodes and 1 reference, “ground” electrode, which is in contrast to the 19 active electrodes and 1 reference electrode used in older children and adults) is due to the smaller cranium of an infant. The standard montages are shown in Figure 2. Cup electrodes (silver Ag/AgCl or gold Au) are attached to the scalp by rubber strips and conductive paste to diminish electrical resistance between the electrodes and the skin (Fig 1).
As the skin of a neonate is highly sensitive, adhesives, as opposed to abrasive pastes, are recommended.6 Moreover, automatic EEG caps for neonates may be used as a convenient alternative for cup electrodes (see Supplemental Digital Content 1, available at http://links.lww.com/JNN/A258), and there are several different-sized caps available, with some as small as 22 to 26 cm in circumference. When using an automatic EEG cap, an EEG conductive gel is applied using a blunt needle syringe. This step, in particular, should be explained in detail to the parents in advance. Our experience suggests that many parents believe that punctures are made on the infant's head when they see a needle being used (even if it is a blunt needle).
There are 2 situations that exclude the use of an EEG cap: (1) when the neonate has a cranially placed intravenous line and (2) when continuous positive air pressure support is attached. Under these circumstances, the cup electrodes must be inserted according to the 10-20 system under the cap used for holding and stabilizing the continuous positive air pressure tube. Intubation and respiratory support do not preclude undertaking an EEG; however, severe abrasions of the epidermis or extensive inflammatory changes of the scalp do rule out the procedure. The impedance between the electrodes and skin should be as low as possible and should not exceed 5000Ω.7 All EEG equipment enables measuring the impedance before starting a recording, whereas more advanced EEG equipment is also able to monitor impedance throughout the entire EEG procedure.
In addition to the electrodes, a breath sensor and 2 heart electrodes are attached to the chest. The heart electrodes are standard cup electrodes attached to the chest with conductive paste at the apex and base of the heart. The breath sensor (which is piezoelectric) is attached using Velcro tape around the chest. If the newborn is in an incubator and wearing a diaper, a breath sensor placed around the diaper will still be able to record good-quality breathing movements. The breath graph curve and ECG curve complement the electrophysiological data.
Video EEG (synchronized recording of EEG tracks and video) should be standard for this age group to allow for the consideration of movement and external artifact (interference) when interpreting the results. The EEG recordings should last at least 1 hour, and the recording of all physiological states (wakefulness, active sleep, and restful sleep) during this period should be possible, which allows full interpretation of the examination. The neonatal EEG is very different when compared with an adult EEG8,9 (see Supplemental Digital Content 2, available at http://links.lww.com/JNN/A259), and its assessment includes (1) continuity of the EEG trace; (2) conceptual age–dependent features, that is, specific waveforms and patterns, as there are specific conceptual age ranges when characteristic EEG features occur; (3) synchrony of the recording (an EEG becomes more synchronous with increasing maturity of the brain); (4) the presence of the sleep-wake cycle; (5) the presence of abnormal EEG patterns, for example, sharp waves; and (6) the presence of neonatal seizures.
Conditions for a Successful Neonatal EEG
The role of the nurse when performing an EEG is essential, and nurses should ensure that the following conditions are met to successfully carry out an EEG examination in a neonate: patient safety, a period of sleep and calm wakefulness in the neonate, and good technical conditions without external interference.
The safety of the patient is a prerequisite while performing an EEG examination. This is especially true, as the status of a premature infant may be unstable. If the handling that is necessary for an EEG examination causes severe deterioration in the health of the neonate, the procedure should be canceled immediately. An experienced nurse can anticipate the feasibility of performing an EEG test before initiating it based on their observations of the child, such as the frequent drop of arterial oxygen saturation measured by pulse oximetry (SaO2). Neonatal oxygen demand increases during the placement of electrodes and sensors; therefore, if oxygen is used, the concentration can be increased to maintain the desired O2 saturation.10 However, after stabilization of the patient, the concentration of the oxygen flow should be returned to the original settings, because either a deficiency or an excess of O2 can be harmful.
While a newborn is typically monitored during an EEG examination, the presence of the EEG technician does not take the place of nursing responsibilities. The cooperation between a trained EEG technician and an experienced nurse plays a crucial role in obtaining a high-quality EEG recording and ensuring the neonate's safety. During an EEG examination, if the need to perform a vital procedure arises, it must have priority. Procedures such as endotracheal suctioning should be performed immediately without waiting for the completion of the EEG.
All procedures should be carried out with special care taken for the cleanliness and sterility of the equipment. The rules and regulations in the neonatal intensive care unit (NICU), including the use of gowns and protective gloves, should be followed to maintain safety. Moreover, the EEG technician should follow the instructions of the nurse in regard to the child's welfare.
Periods of Sleep and Calm Wakefulness
An EEG recording requires periods of active sleep, quiet sleep, and wakefulness in the neonate.11,12 During sleep, the neonate produces almost no movement-related artifact, and the nature of the EEG recording is different from a state of wakefulness. Obtaining these sleep periods is not always easy and requires approximately 1 to 2 hours. Although silence and dim lighting promote sleep, nursing support at this stage is important. Typically, the nurse is able to identify and provide the conditions required for the neonate's sleep. They know the sleep-wake cycle of the individual newborn, the optimal sleep position, and the frequency of feeding. It is helpful to prepare for an EEG examination just before feeding, which should be started after all electrodes and sensors have been attached. Feeding usually calms a baby and is conducive to falling asleep.
Implementing kangaroo care during the neonatal period is recommended to establish close relationships between mother and child and has been shown to be a natural way to calm a neonate.13 As such, there are several advantages to performing an EEG examination during the kangaroo process. First, managing newborns while preparing them for an examination is easier when performed outside an incubator. Second, during the kangaroo process, the neonate is typically relaxed and already prepared to fall asleep.14 Moreover, a mother who participates in the examination is more familiar with it and may be less worried about the procedure. However, there are disadvantages, including possible movements by the mother that create artifact and the difficulty involved in finding a convenient time for performing both kangaroo care and the EEG.
In some cases, particularly in newborns with central nervous system impairments, the infant may not sleep, or the child constantly moves and cries. In such instances, the use of sedatives may be justified, although many of these drugs can affect the EEG recording, depressing the electrocortical background activity.15 Midazolam, a short-acting, hypnotic-sedative drug, is one possible choice; however, midazolam can slow or stop breathing, so vital signs must be closely monitored after its administration.
Artifacts are part of an EEG recording that should be avoided if possible. Sometimes, despite the use of both hardware and software filters, the external electromagnetic field causes disturbances, which make performing an EEG examination impossible. In these circumstances, it is recommended to look for the source of interference, such as an external heater, a lamp, and so forth, which should be turned off. Sometimes, inserting the machine's power plug into a different outlet resolves the problem. However, if a respirator is the source of the electromagnetic noise, obtaining a high-quality EEG recording may not be possible. When all of the electrodes experience interference, 1 method may be used to eliminate it. Brainbox ISO-1032 CE EEG amplifiers (Braintronics B.V.) offer an option to use active reference G1/G2 electrodes. The G1 electrode transmits a collective voltage signal, and the G2 electrode directs an opposite phase signal to eliminate the attenuation of the voltage signal at the electrode G1. These must be placed close to one another in the area where a standard reference electrode GND is usually placed. Only 1 hardware reference type can be used at a time—the standard (GND, R) or active (G1/G2).
Passing close to EEG equipment during a recording can also cause artifact. This type of interference is usually not captured by video cameras, which are focused on the patient and not the surroundings. Therefore, both staff and parents should avoid walking close to working equipment. Artifacts related to an infant's movement such as blinking, hiccups, touching, massage, and respiratory motions are easily detected and accounted for when using the video recording taken during an EEG session.
The Nursing Role During Neonatal EEG
Very small for gestational age neonates need sophisticated care that can be provided by a team from a neonatal ward.16,17 Three factors determine the quality of care they receive: knowledge, experience, and attitude. Nurses working in NICUs are, in most instances, able to fulfill all of these conditions.18 Therefore, it is unsurprising that many EEG technicians may have less experience in dealing with VSGA newborns, and it is reasonable to expect some of the responsibilities for undertaking EEG examinations on VSGA infants are transferred to nurses. These responsibilities include applying electrodes and sensors according to the international 10-20 system, controlling the electrodes to maintain the desired resistance, and noting any artifact caused by movement, feeding, or touching the baby.
Performing a neonatal EEG is a highly complex task requiring both experience and commitment. We are firmly convinced that NICU nurses are the most appropriate for performing EEG tests in neonates, and they should be trained in basic electrophysiology. Consequently, we suggest including a basic course in neuroelectrophysiology in the syllabi for nursing specializations in neonatal intensive care.
A combination of high-quality video-EEG equipment, a well-trained nursing team, and electroneurodiagnostic technicians can guarantee a successful EEG examination on VSGA infants. Moreover, the key condition for a successful examination and maintaining safety rules is good cooperation between nurses, EEG technicians, and parents.18 An EEG examination for neonates weighing less than 1500 g and/or those requiring respiratory support should be performed only by a trained NICU nurse. When data are obtained in this way and used in combination with clinical data, optimal EEG results can be provided for the clinical neurophysiologist.
We would like to thank Editage (www.editage.com) for English-language editing.
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