Sedation, anesthesia, and physiologic monitoring during MR imaging: evaluation of procedures and equipment

Assessment of the practice of pediatrics procedural sedation and analgesia for magnetic resonance imaging and computed tomography scan at a teaching hospital, Ethiopia, 2020: A clinical audit

BACKGROUND

The main goals of paediatric sedation/general anesthesia vary according to the specific imaging procedure, but generally includes anxiety relief, pain control and control of excessive movement. The quality of magnetic resonance imaging (MRI) and computed tomography (CT) depends largely on immobility of the patient during the procedure, which is often difficult to achieve without sedation in children. Sedation is the depression of the central nervous system and reflexes by the administration of drugs. Brain imaging is routinely used to identify stroke, hemorrhage, and structural abnormalities. All patients undergoing procedural sedation and those receiving general anesthesia should be evaluated equally.

AIM

The study aimed to perform a clinical audit of sedation and analgesia practices for magnetic resonance imaging and computed tomography compared against the guidelines/standards to determine if practice meets the standards and identify areas of non-compliance at a teaching Referral Hospital in Ethiopia.

METHODS

This clinical audit was conducted from January 1 to May 30/2020 for 5 months at a teaching Referral Hospital in Ethiopia. All children below the age of 6 years underwent MRI and CT imaging procedures under sedation during a study period were included. Data were collected through direct observation using checklists of standards by a trained data collector. Descriptive statistics were presented with tables, graphs of sums and percentages of items using SPSS version 20.

RESULTS

A total of 40 children underwent MRI and CT imaging were observed at the Hospital imaging sites. Among the 20 standards, 6 of them had 100% compliance rate, 3 of the standards had 0% complaince rate and 11 of the standards had the compliance rate of between 0 and 100%.

CONCLUSIONS AND RECOMMENDATIONS

In general, even though the practice guidelines of procedural sedation for MRI and CT recommend to practice procedures based on the standards, this study showed there were a number of standards that had <100% compliance rate. Therefore, it is recommended that staff should adopt standards or locally prepared protocols for their day-to-day practice.

Ensuring safety and functionality of electroglottography measurements during dynamic pulmonary MRI

PURPOSE

To combine vocal tract measurements with dynamic MRI of the lungs to provide fundamental insights into the lung physiology during singing.

METHODS

To analyze vocal fold oscillatory patterns during dynamic lung MRI, an electroglottography (EGG) system was modified to allow for simultaneous EGG measurements during MR image acquisitions. A low-pass filter was introduced to suppress residual radiofrequency (RF) coupling into the EGG signal. RF heating was tested in a gel phantom to ensure MR safety, and functionality of the EGG device was assessed in a volunteer experiment at singing frequencies from A5 to A3. In the recorded EGG signals, remaining RF interferences were removed by independent component analysis post processing, and standard EGG parameters such as fundamental frequency, contact quotient and jitter were calculated. In a second volunteer experiment, EGG recordings were compared with lung diameter measurements from 2D time-resolved trueFISP acquisitions.

RESULTS

RF heating measurements resulted in less than 1.2°C temperature increase in the gel phantom. EGG parameters measured during MR imaging are within the range of ideal values. In the lung measurement, both the lung diameter and the EGG recordings could be successfully performed with only minimal interference.

CONCLUSION

EGG recording is pos sible during dynamic lung MRI, and glottal activity can be studied safely at 1.5T. Magn Reson Med 76:1629-1635, 2016. © 2015 International Society for Magnetic Resonance in Medicine.

Practice advisory on anesthetic care for magnetic resonance imaging: an updated report by the american society of anesthesiologists task force on anesthetic care for magnetic resonance imaging

The American Society of Anesthesiologists Committee on Standards and Practice Parameters and the Task Force on Anesthetic Care for Magnetic Resonance Imaging presents an updated report of the Practice Advisory on Anesthetic Care for Magnetic Resonance Imaging.

Supplemental Digital Content is available in the text.

Neuroinformatics challenges to the structural, connectomic, functional and electrophysiological multimodal imaging of human traumatic brain injury

Throughout the past few decades, the ability to treat and rehabilitate traumatic brain injury (TBI) patients has become critically reliant upon the use of neuroimaging to acquire adequate knowledge of injury-related effects upon brain function and recovery. As a result, the need for TBI neuroimaging analysis methods has increased in recent years due to the recognition that spatiotemporal computational analyses of TBI evolution are useful for capturing the effects of TBI dynamics. At the same time, however, the advent of such methods has brought about the need to analyze, manage, and integrate TBI neuroimaging data using informatically inspired approaches which can take full advantage of their large dimensionality and informational complexity. Given this perspective, we here discuss the neuroinformatics challenges for TBI neuroimaging analysis in the context of structural, connectivity, and functional paradigms. Within each of these, the availability of a wide range of neuroimaging modalities can be leveraged to fully understand the heterogeneity of TBI pathology; consequently, large-scale computer hardware resources and next-generation processing software are often required for efficient data storage, management, and analysis of TBI neuroimaging data. However, each of these paradigms poses challenges in the context of informatics such that the ability to address them is critical for augmenting current capabilities to perform neuroimaging analysis of TBI and to improve therapeutic efficacy.

Intensity-modulated microbend fiber optic sensor for respiratory monitoring and gating during MRI

This paper describes a novel microbend fiber optic sensor system for respiratory monitoring and respiratory gating in the MRI environment. The system enables the noninvasive real-time monitoring and measurement of breathing rate and respiratory/body movement pattern of healthy subjects inside the MRI gantry, and has potential application in respiratory-gated image acquisition based on respiratory cues. The working principle behind this sensor is based on the microbending effect of an optical fiber on light transmission. The sensor system comprises of a 1.0-mm-thin graded-index multimode optical fiber-embedded plastic sensor mat, a photoelectronic transceiver, and a computer with a digital signal processing algorithm. In vitro testing showed that our sensor has a typical signal-to-noise ratio better than 28 dB. Clinical MRI trials conducted on 20 healthy human subjects showed good and comparable breathing rate detection (with an accuracy of ±2 bpm) and respiratory-gated image quality produced using the sensor system, with reference to current predicate hospital device/system. The MRI safe, ease of operation characteristics, low fabrication cost, and extra patient comfort offered by this system suggest its good potential in replacing predicate device/system and serve as a dual function in real-time respiratory monitoring and respiratory-gated image acquisition at the same time during MRI.

Sleep deprivation for pediatric sedated procedures: not worth the effort

OBJECTIVE

Sleep deprivation is commonly used to enhance the effectiveness of pediatric sedation and to decrease sedation failures. We reviewed our sedation database to evaluate the efficacy of sleep deprivation.

METHODS

The entire pediatric sedation unit database (n = 5640) was reviewed retrospectively. Patients without complete data sets were excluded. The remaining patients were separated into 2 groups: 3272 patients who underwent noninvasive procedures and 1210 who underwent invasive procedures. A subgroup of noninvasive procedure patients <2 years old (n = 1398) was also analyzed. The sedation failure rate (%) and nursing care hours for both sleep-deprived and non-sleep-deprived patients were analyzed.

RESULTS

In the noninvasive procedure group, the sedation failure rate was 5.7% for the sleep-deprived patients and 5.6% for the non-sleep-deprived patients, whereas the sedation failure rate for children <2 years old was 4.2% for sleep-deprived patients and 4.7% for non-sleep-deprived patients. The sedation failure rate in the invasive procedure group was 7.5% for sleep-deprived patients and 7.2% for non-sleep-deprived patients. Nursing care hours in the noninvasive procedure group were significantly longer for the sleep-deprived patients (4.5 +/- 1.6 hours) versus the non-sleep-deprived patients (3.8 +/- 1.6 hours). This finding was true also for the subgroup of children <2 years old (sleep-deprived patients: 4.2 +/- 1.4 hours; non-sleep-deprived patients: 3.5 +/- 1.4 hours). No difference was noted in nursing care hours for the invasive procedure group.

CONCLUSIONS

Sleep deprivation had no effect in reducing the pediatric sedation failure rate. The patients having noninvasive procedures who were sleep deprived required significantly more nursing care hours than their non-sleep-deprived counterparts. Routine use of sleep deprivation for pediatric sedation should be critically reevaluated.

MR imaging-guided prostate biopsy with surgical navigation software: device validation and feasibility

Magnetic resonance (MR) imaging--guided prostate biopsy in a 0.5-T open imager is described, validated in phantom studies, and performed in two patients. The needles are guided by using fast gradient-recalled echo and T2-weighted fast spin-echo images. Surgical navigation software provided T2-weighted images critical to targeting the peripheral zone and the tumor. MR imaging can be used to guide prostate biopsy.

Radiofrequency energy-induced heating during MR procedures: a review

During an MR procedure, most of the transmitted RF power is transformed into heat within the patient's tissue as a result of resistive losses. Not surprisingly, the primary bioeffects associated with the RF radiation used for MR procedures are directly related to the thermogenic qualities of this electromagnetic field. This review article discusses the characteristics of RF energy-induced heating associated with MR procedures, with an emphasis on thermal and other physiologic responses observed in human subjects.

The use of play therapy in the preparation of children undergoing MR imaging

Magnetic resonance (MR) imaging has become an important technique in the evaluation of a wide range of congenital and acquired conditions in children. The ability to image in multiple anatomic planes without the use of ionizing radiation has particular advantages. However scan times can be long, and the narrow bore and noise generated by most units make the procedure very intimidating to the young child. The use of surface coils may exacerbate this, often necessitating recourse to sedation or anaesthesia. We describe a technique involving play therapy which we have found useful in the preparation of young children for MR imaging and which has reduced the number of non-diagnostic scans and the need for sedation or anaesthesia.

Recording of EEG during fMRI experiments: patient safety

The acquisition of electroencephalograms (EEG) during functional magnetic resonance imaging (fMRI) experiments raises important practical issues of patient safety. The presence of electrical wires connected to the patient in rapidly changing magnetic fields results in currents flowing through the patient due to induced electromotive forces (EMF), by three possible mechanisms: fixed loop in rapidly changing gradient fields; fixed loop in a RF electromagnetic field; moving loop in the static magnetic field. RF-induced EMFs were identified as the most important potential hazard. We calculated the minimum value of current-limiting resistance to be fitted in each EEG electrode lead for a representative worst case loop, and measured RF magnetic field intensity and heating in a specific type of current-limiting resistors. The results show that electrode resistance should be > or = 13 k(omega) for our setup. The methodology presented is general and can be useful for other centers.

Does a sedative dose of chloral hydrate modify the EEG of children with epilepsy?

Chloral hydrate (CH) is used to sedate children unable to cooperate during investigations such as EEG requiring the patient to be still. It is not known if CH or its metabolites modify the EEG and our aim was to answer this question. Recordings of the EEG before, during and after rectal administration of CH (50-77 mg/kg) in 13 children aged 1.5-13.5 years with severe epilepsy and additional neurological impairments were made. All children had frequent spike-wave activity before CH. In 9 children CH had no effect on the EEG. In 3 children there was a significant reduction in epileptic activity after 20-50 min and in one a significant increase. Cardiovascular parameters were stable throughout. At sedative doses, CH can generally be used before an EEG recording without loss of information but in 4 out of 13 children there were changes which could alter interpretation.