Testing of adult and paediatric ventilators for use in a magnetic resonance imaging unit

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.

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Usefulness of 3D reconstructed computed tomography imaging for double outlet right ventricle

BACKGROUND/PURPOSE

To evaluate the value of 3D reconstructed computed tomography (CT) imaging for patients with double outlet right ventricle (DORV).

METHODS

CT images were obtained preoperatively from 17 patients who ranged in age from 5 days to 5 years. Reconstructed 3D images were created using gradient-shading surface rendering, which allowed partial subtraction of the anterior sections of the virtual heart to view the interior. Interpretations of CT, echocardiography and cine-cardioangiography were compared and verified from surgical findings, autopsy, and consensus upon review of all imaging and diagnostic tests.

RESULTS

Three subaortic, seven subpulmonary, six non-committed, and one double-committed subtypes of ventricular septal defect (VSD) were observed. The 3D electron beam CT images provided good delineation of the spatial relationship inside the heart. The range of diagnostic accuracy for all VSD types in DORV was 88-100% for 3D CT, 71-94% for echocardiography, and 60-100% for cine-cardioangiography. In comparison, 3D CT offered better diagnostic accuracy for all variants of DORV.

CONCLUSION

3D constructed CT imaging is a good modality for differentiating VSD type in DORV. It allowed us to directly evaluate the inside of cardiac chambers for the right ventricular outlet, great arterial root, and determine the VSD relationships.

Anaesthesia for magnetic resonance imaging/computed tomography

The need for general anaesthesia for magnetic resonance imaging/computed tomography investigations can be reduced by the implementation of structured sedation programmes supervised by anaesthetists. Despite its side-effects, chloral hydrate is still the drug most widely used. Rectal thiopental or intravenous propofol are suggested anaesthetic agents for pre-school children and uncooperative or claustrophobic individuals. Spiral computed tomography scans and ultrafast magnetic resonance imaging shorten immobilization times further. However, functional magnetic resonance imaging and intervention techniques in neuroradiology depend on a motionless patient. A useful strategy for testing anaesthesia equipment has been outlined.

Assessment of the Caradyne WhisperFlow for administration of continuous positive airway pressure in a 3 Tesla magnetic resonance scanner

Demand for magnetic resonance investigations in critically ill patients is increasing. While these patients frequently need ventilatory support, not all of them require controlled ventilation and many may be treated with continuous positive airway pressure. Controlled ventilation, with the concurrent need for sedation, may be inappropriate when airway physiology is being studied and may retard weaning. No commercially available ventilator designed for the magnetic resonance environment can deliver high flow continuous positive airway pressure. We tested the Caradyne Whisperflow flow generator and five Whisperflow valves (2.5-15 cmH2O airway pressure) within a 3 Tesla environment for safety and possible dysfunction. All components had minimal ferromagnetic properties and tests showed no clinically relevant change in flow delivery or oxygen concentration in the magnetic field. In addition, the airway pressure generated by the valves was not affected by the magnetic field. We conclude that the tested system can be safely used in a 3 Tesla magnetic resonance environment.