[Anesthesia for magnetic resonance tomography in neonates, infants and young children]. 1997

W Funk, and K Hörauf, and P Held, and K Taeger
Klinik für Anästhesiologie, Klinikum der Universität Regensburg.

BACKGROUND Since patient cooperation in neonates and infants up to 5 years is always reduced, deep sedation is usually recommended to obtain constant high-quality images during MRI. According to the widely accepted AAP Guidelines, deep sedation is not always distinguishable from general anesthesia, substantiating the demand for state-of-the-art anaesthesia. This is particularly true in this age group, where pharmacokinetics and pharmacodynamics show wide interindividual variation. In this review we outline the techniques required to provide safe and effective patient care in the unique MRI environment. From the viewpoint of induction time, half-life of action and success rate, we have found that inhalation anesthetics and propofol present clear advantages. Both offer rapid induction and emergence, allowing outpatient examinations in a tight schedule with a reliable sedation state. Tracheal intubation or a laryngeal mask airway is required to supply volatile anesthetics and to secure the airway, since propofol in appropriate doses causes respiratory depression and loss of the protective reflexes. Positive-pressure ventilation is recommended since the reduction of tidal volumes by sedative drugs (including high-dose chloral hydrate, barbiturates) may cause atelectasis and decreased oxygen saturation. Several respirators work well outside a critical magnetic field strength of 10 mT (e.g. Draeger: Titus, Siemens: Servo 900). The use of long low-compliance tubing (4-5 m) allows the respirator to be placed at the distal end of the patient table. Sidestream capnometry and spirometry at the proximal tube connector facilitate compensation for losses in tidal volume due to gas compression. Syringe pumps work properly when kept outside the 10 mT line. Some defibrillators (e.g., Lifepac, Physiocontrol) are approved for use in strong magnetic fields. State-of-the-art monitoring is also attainable for high-risk patients, including invasive pressure measurement. Since wiring without special filters may not cross the HF shield of the examination room, hydraulic and pneumatic systems are used (blood pressure by oscillometry, airway monitoring by side-stream spirometry). Optical fibers are used for pulse oximetry. A telemetric EKG is usually provided by the MRT manufacturer. Because oscilloscopes are distorted by the magnetic field, the monitors are placed outside the examination room. In addition, this eliminates the possibility of erasing the EPROMs contained in most monitors. METHODS With the setup described, the presence of a second anesthetist within the examination room is superfluous. A second anesthesia team can shorten the time lag between examinations by overlapping induction if a separate anesthesia induction and emergence room is provided. CONCLUSIONS The level of sedation required for MRI in newborn and infants can only be achieved safely and efficiently by general anesthesia performed by trained staff. Complete state-of-the-art anesthesia care can be delivered if appropriate instrumentation is used.

UI MeSH Term Description Entries
D007223 Infant A child between 1 and 23 months of age. Infants
D007231 Infant, Newborn An infant during the first 28 days after birth. Neonate,Newborns,Infants, Newborn,Neonates,Newborn,Newborn Infant,Newborn Infants
D008279 Magnetic Resonance Imaging Non-invasive method of demonstrating internal anatomy based on the principle that atomic nuclei in a strong magnetic field absorb pulses of radiofrequency energy and emit them as radiowaves which can be reconstructed into computerized images. The concept includes proton spin tomographic techniques. Chemical Shift Imaging,MR Tomography,MRI Scans,MRI, Functional,Magnetic Resonance Image,Magnetic Resonance Imaging, Functional,Magnetization Transfer Contrast Imaging,NMR Imaging,NMR Tomography,Tomography, NMR,Tomography, Proton Spin,fMRI,Functional Magnetic Resonance Imaging,Imaging, Chemical Shift,Proton Spin Tomography,Spin Echo Imaging,Steady-State Free Precession MRI,Tomography, MR,Zeugmatography,Chemical Shift Imagings,Echo Imaging, Spin,Echo Imagings, Spin,Functional MRI,Functional MRIs,Image, Magnetic Resonance,Imaging, Magnetic Resonance,Imaging, NMR,Imaging, Spin Echo,Imagings, Chemical Shift,Imagings, Spin Echo,MRI Scan,MRIs, Functional,Magnetic Resonance Images,Resonance Image, Magnetic,Scan, MRI,Scans, MRI,Shift Imaging, Chemical,Shift Imagings, Chemical,Spin Echo Imagings,Steady State Free Precession MRI
D008297 Male Males
D008991 Monitoring, Physiologic The continuous measurement of physiological processes, blood pressure, heart rate, renal output, reflexes, respiration, etc., in a patient or experimental animal; includes pharmacologic monitoring, the measurement of administered drugs or their metabolites in the blood, tissues, or urine. Patient Monitoring,Monitoring, Physiological,Physiologic Monitoring,Monitoring, Patient,Physiological Monitoring
D010348 Patient Care Team Care of patients by a multidisciplinary team usually organized under the leadership of a physician; each member of the team has specific responsibilities and the whole team contributes to the care of the patient. Health Care Team,Interdisciplinary Health Team,Medical Care Team,Multidisciplinary Care Team,Multidisciplinary Health Team,Healthcare Team,Care Team, Health,Care Team, Medical,Care Team, Multidisciplinary,Care Team, Patient,Care Teams, Health,Care Teams, Patient,Health Care Teams,Health Team, Interdisciplinary,Health Team, Multidisciplinary,Healthcare Teams,Interdisciplinary Health Teams,Medical Care Teams,Multidisciplinary Care Teams,Multidisciplinary Health Teams,Patient Care Teams,Team, Health Care,Team, Healthcare,Team, Interdisciplinary Health,Team, Medical Care,Team, Multidisciplinary Care,Team, Multidisciplinary Health,Team, Patient Care,Teams, Interdisciplinary Health
D002675 Child, Preschool A child between the ages of 2 and 5. Children, Preschool,Preschool Child,Preschool Children
D005260 Female Females
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000768 Anesthesia, General Procedure in which patients are induced into an unconscious state through use of various medications so that they do not feel pain during surgery. Anesthesias, General,General Anesthesia,General Anesthesias

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