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

Perioperative management and drug selection for sedated/anesthetized patients undergoing MRI examination: A review

In recent years, magnetic resonance imaging (MRI) technology has become an indispensable imaging tool owing to significant improvements in MRI that have opened up new diagnostic perspectives. Due to the closed environment, long imaging time, and need to remain still during the examination process, the examiner may cannot cooperate with the completion of the examination of the procedure, which increases the need for deep sedation or anesthesia. Achieving this can sometimes be challenging, especially in the special nontraditional environment of MRI equipment (unfamiliar and narrow spaces, away from patients, strong magnetic fields) and in special populations requiring sedation/anesthesia during examinations, which pose certain challenges for the perioperative anesthesia management of MRI. A simple "checklist" is necessary because it allows the anesthesiologist to become familiar with the particular environment and human and material resources as quickly as possible. For the choice of sedative/anesthetic, the traditional drugs, such as midazolam and ketamine, are still used due to the ease of administration despite their low sedation success rate, prolonged recovery, and significant adverse events. Currently, dexmedetomidine, with respiratory drive preservation, propofol, with high effectiveness and rapid recovery, and sevoflurane, which is mild and nonirritating, are preferred for sedation/anesthesia in children and adults undergoing MRI. Therefore, familiarity with the perioperative management of patient sedation and general anesthesia and drug selection in the MRI environment is critical for successful surgical completion and for the safe and rapid discharge of MRI patients receiving sedation/anesthesia.

Dexmedetomidine versus Propofol: Is One Better Than the Other for MRI Sedation in Children?

Objective The aim of this article is to determine whether dexmedetomidine or propofol is better for MRI sedation in children. Design This study is a retrospective review of patients sedated with dexmedetomidine or propofol for MRI between July 2007 and July 2015. Dexmedetomidine group (group D) was administered a bolus of 2 µg/kg over 10 minutes followed by a 1 ug/kg/hour infusion. Propofol group (group P) received a bolus of 2 mg/kg over 2 minutes followed by 83 µg/kg/minute infusion. Results Of the 996 cases completed, 452 were in group P and 544 were in group D. Patients in group P were heavier and older than those in group D. All the patients except one in group D completed the procedures. Hypotension occurred in 59% in group P versus 4% in group D (89 ± 11.4 SBP vs. 103.80 ± 19.4; p < 0.05). Bradycardia was observed in 2.9% in group P versus 0.6% in group D. Apnea occurred in two patients in group D. Although procedure time was longer in patients receiving propofol versus dexmedetomidine (58.87 ± 28.17 vs. 45 ± 23.6; p < .05), the discharge time was significantly shorter (37. ± 12.30 vs. 92.61 ± 28.19; p < 0.05). Conclusion Dexmedetomidine appears to provide a useful alternative to propofol for MRI sedation with a longer recovery time, stable hemodynamics, and less reliable respiratory profile, while the propofol had the advantage of quicker onset and rapid recovery.

Comparison of DXA Scans and Conventional X-rays for Spine Morphometry and Bone Age Determination in Children

Conventional lateral spine and hand radiographs are the standard tools to evaluate vertebral morphometry and bone age in children. Beside bone mineral density analyses, dual-energy X-ray absorptiometry (DXA) measurements with lower radiation exposure provide high-resolution scans which are not approved for diagnostic purposes. Data about the comparability of conventional radiographs and DXA in children are missing yet. The purpose of the trial was to evaluate whether conventional hand and spine radiographs can be replaced by DXA scans to diminish radiation exposure. Thirty-eight children with osteogenesis imperfecta or secondary osteoporosis or short stature (male, n=20; age, 5.0-17.0 yr) were included and assessed once by additional DXA (GE iDXA) of the spine or the left hand. Intraclass correlation coefficients (ICCs) were used to express agreement between X-ray and iDXA assessment. Evaluation of the spine morphometry showed reasonable agreement between iDXA and radiography (ICC for fish-shape, 0.75; for wedge-shape, 0.65; and for compression fractures, 0.70). Bone age determination showed excellent agreement between iDXA and radiography (ICC, 0.97). IDXA-scans of the spine in a pediatric population should be used not only to assess bone mineral density but also to evaluate anatomic structures and vertebral morphometry. Therefore, iDXA can replace some radiographs in children with skeletal diseases.

Anesthetic management of a newborn with occipital meningocele for magnetic resonance imaging

Cranial Meningocoele is a term which represents herniation of meninges and cerebrospinal fluid through the congenital defect in the cranium. Anaesthetic challenges in the management of neonates with occipital meningocoele include airway management and proper positioning of the neonate without pressure on the meningocoele sac so as to preventthe rupture of the membranes. Associated congenital anomalies also can cause anaesthesia and procedure related complications. Other difficulties include performing a difficult airway case in an unfamiliar environment outside operation theatre. We report a case of 6 day old neonate with occipital meningocoele posted for MRI brain and the successful anaesthetic management.

Anästhesie außerhalb des Zentral-OP

The number of diagnostic and surgical procedures being performed outside the core operating area is growing disproportionately. Due to the higher perioperative risk for such patients, anesthesia should only be provided by a very experienced anesthesiologist, even for supposedly small interventions. At these locations, timely and direct access to the anesthesia machine and/or the patient is often limited and if additional personnel or supplies are required, substantial time delays usually occur and should be allowed for. Standard operating procedures that are optimized to local requirements and providing a specially equipped anesthesia trolley for diagnostic and surgical procedures outside of the core operating area, may decrease the likelihood of complications induced by poorly equipped anesthesia workplaces. For electroconvulsive therapy (ECT), the standard drugs are methohexital in combination with short-acting opioids, such as remifentanil and succinylcholine. Significant variations in arterial blood pressure and heart rate are possible. Anesthesia induction in children with a known difficult airway or difficult intravascular access should initially be performed in a location with optimal infrastructure with subsequent transfer to the diagnostic or surgical suite outside the core operating area. Before entering the magnetic resonance imaging (MRI) suite, personal ferromagnetic items (e.g. pens, credit cards, stethoscopes, keys, telephones, USB sticks) should be removed to prevent injury and data loss; a MRI-compatible anesthesia machine and equipment is compulsory. Patients with cardiac pacemakers, cochlea implants, aneurysm or other clips, metallic-based tattoos or make-up are not normally compatible with MRI. General anesthesia should be preferred over conscious sedation for magnetic resonance imaging and ear protection is necessary for anesthetized patients. Gastroscopy in children should be performed under general anesthesia; and when concluding the procedure, air insufflated into the gastrointestinal tract should be suctioned in all patients. For angiography, maximum monitoring needs to be available to provide hemodynamically unstable patients with adequate anesthesia care; comprehensive radiation protection for patients and staff as well as temperature monitoring for prolonged diagnostic procedures is also necessary. Monitoring oxygen saturation and end-tidal carbon dioxide as well as employing visual and audible alarms is an essential requirement even during conscious sedation. In summary, the number of diagnostic and surgical procedures performed outside the core operating area should be reduced to a minimum and, whenever possible, diagnostic or surgical procedures should be performed within the core operating area.

Sedation and analgesia for brief diagnostic and therapeutic procedures in children

The number of diagnostic and therapeutic procedures done outside of the operating room and the intensive care unit has increased substantially in recent years. In parallel, the management of acute pain and anxiety in children undergoing therapeutic and diagnostic procedures has developed considerably in the past two decades. The primary goal of procedural sedation and analgesia is the safe and efficacious control of emotional distress and pain. The availability of non-invasive monitoring, short-acting opioids and sedatives has broadened the possibilities of sedation and analgesia in children in diverse settings. While most of these procedures themselves pose little risk to the child, the administration of sedation or analgesia may add substantial risk to the patient. This article reviews the current status of sedation and analgesia for invasive and non-invasive procedures in children providing an evidence-based approach to several topics of importance, including patient assessment, personnel requirements, equipment, monitoring, and drugs.

Anesthetic Management for Thoracopagus Twins with Complex Cyanotic Heart Disease in the Magnetic Resonance Imaging Suite

We report a case of thoracopagus twins undergoing magnetic resonance imaging (MRI) studies under general anesthesia. The twins had a complex shared cardiac anatomy that posed additional challenges to an already-difficult anesthesia care area. This report emphasizes the approach to anesthetic management of conjoined twins in the MRI environment.

Effects of low dose ketamine before induction on propofol anesthesia for pediatric magnetic resonance imaging

BACKGROUND

We aimed to investigate effects of low dose ketamine before induction on propofol anesthesia for children undergoing magnetic resonance imaging (MRI).

METHODS

Forty-three children aged 9 days to 7 years, undergoing elective MRI were randomly assigned to receive intravenously either a 2.5 mg x kg(-1) bolus of propofol followed by an infusion of 100 microg x g(-1) x min(-1) or a 1.5 mg x kg(-1) bolus of propofol immediately after a 0.5 mg x kg(-1) bolus of ketamine followed by an infusion of 75 microg x kg(-1) x min(-1). If a child moved during the imaging sequence, a 0.5-1 mg x kg(-1) bolus of propofol was given. Systolic and diastolic blood pressures, heart rate, peripheral oxygen saturation and respiratory rates were monitored. Apnea, the requirement for airway opening maneuvers, secretions, nausea, vomiting and movement during the imaging sequence were noted. Recovery times were also recorded.

RESULTS

Systolic blood pressure and heart rate decreased significantly in the propofol group, while blood pressure did not change and heart rate decreased less in the propofol-ketamine group. Apnea associated with desaturation was observed in three patients of the propofol group. The two groups were similar with respect to requirements for airway opening maneuvers, secretions, nausea-vomiting, movement during the imaging sequence and recovery time.

CONCLUSIONS

Intravenous administration of low dose ketamine before induction and maintenance with propofol preserves hemodynamic stability without changing the duration and the quality of recovery compared with propofol alone.

Propofol for pediatric radiotherapy

OBJECTIVE

Pediatric radiotherapy is a day care procedure. In children, anaesthesia is necessary to prevent movement during the therapy. Traditionally intramuscular ketamine is used for these procedure because of its inherent safety in a child who used to be left alone in the cobalt room.

METHODS

This study was designed to explore the efficacy of propofol and ketamine in pediatric radiotherapy in nineteen children. The inclusion criteria was a child fasting for six hours with no fever or URTI in the past week. A child coming to the radiotherapy (RT) unit without an intravenous cannula was given intramuscular ketamine 10 mg/kg and taken for the procedure. Before the child recovered from anaesthesia an intravenous cannula, 20-22G, Vasofix was inserted for subsequent sittings of RT. The child coming with an intravenous cannula was given propofol 2.5 mg/kg with xylocaine (0.1 mg/kg) without adrenaline. The parameters recorded were pulse rate, oxygen saturation and respiratory rate-baseline to every 30 seconds till five minutes. Onset time, recovery time, oral feeding time and any untoward effects like nausea, vomiting, nystagmus were also noted.

RESULT

The drug was graded on a scale of 0-10 according to parental acceptability where 0 is the worst and 10 is the best acceptability. The mean (+/-SD) of all the measured parameters were calculated and compared between the two groups.

CONCLUSION

Propofol was associated with faster onset, better recovery, early oral feeding time, no nausea and vomiting and better parental acceptability. There was no hypotension, bradycardia and oxygen saturation at 60 seconds, which was between 94-95%, was easily treatable with supplementation of oxygen by face mask.

Anaesthesia with midazolam and S-(+)-ketamine in spontaneously breathing paediatric patients during magnetic resonance imaging

We evaluated safety and efficacy of a sedation technique based on rectal and intravenous S-(+)-ketamine and midazolam to achieve immobilization during Magnetic Resonance Imaging (MRI). Thirty-four paediatric patients were randomly assigned to undergo either the sedation protocol (study group) or general anaesthesia (control group). Imaging was successfully completed in all children. Children in the study group received a rectal bolus (0.5 mg x kg(-1) midazolam and 5 mg x kg(-1) S-(+)-ketamine) and required additional i.v. supplementation (20+/-10 microg x kg(-1) x min(-1) S-(+)-ketamine and 4+/-2 microg x kg(-1) x min(-1) midazolam), spontaneous ventilation was maintained. Transient desaturation occurred once during sedation and four times in the control group (P=0.34). PECO2 was 5.3+/-0.5 kPa (40+/-4 mm Hg) in the study group and 4.1+/-0.6 kPa (31+/-5 mm Hg) in the control group (P<0.001). Induction and discharge times were shorter in the study group (P<0.001), recovery times did not differ significantly between the groups. Our study confirms that a combination of rectal and supplemental intravenous S-(+)-ketamine plus midazolam is a safe and useful alternative to general anaesthesia for MRI in selected paediatric patients.