Charlotte Bell

ACR Guidance Document for Safe MR Practices: 2007

E. Kanal is a consultant for, is a member of the speakers bureau of, and provides research support for Bracco Diagnostics and GE Healthcare; is a member of the speakers bureau of and provides research support for Siemens Medical Solutions; and provides research support for Berlex and Medtronic. T. Gilk is a consultant for Mednovus, Inc. J. R. Gimbel provides research support for St. Jude Medical, Medtronic, and Biotronik. J. Nyenhuis is a consultant for and provides research support to Medtronics. J. Weinreb is a consultant and member of the speakers bureau for GE Healthcare.

ACR guidance document on MR safe practices: 2013

Because there are many potential risks in the MR environment and reports of adverse incidents involving patients, equipment and personnel, the need for a guidance document on MR safe practices emerged. Initially published in 2002, the ACR MR Safe Practices Guidelines established de facto industry standards for safe and responsible practices in clinical and research MR environments. As the MR industry changes the document is reviewed, modified and updated. The most recent version will reflect these changes. J. Magn. Reson. Imaging 2013;37:501–530.

Premedication in the United States: a status report.

We undertook a mailing survey study to assess the current practice of sedative premedication in anesthesia.A total of 5396 questionnaires were mailed to randomly selected physician members of the American Society of Anesthesiologists. Forty-six percent (n = 2421) of those sampled returned the questionnaire after two mailings. The reported rate of sedative premedication in the United States varied widely among age groups and geographical locations. Premedicant sedative drugs were least often used with children younger than age 3 years and most often used with adults less than 65 years of age (25% vs 75%, P = 0.001). Midazolam was the most frequently used premedicant both in adults and children (>75%). When analyzed based on geographical locations, use of sedative premedicants among adults was least frequent in the Northeast region and most frequent in the Southeast region (50% vs 90%, P = 0.001). When the frequency of premedication was examined against health maintenance organization (HMO) penetration (i.e., HMO enrollment by total population) in the various geographical regions, correlation coefficients (r) ranged from -0.96 to -0.54. Multivariable analysis revealed that HMO penetration is an independent predictor for the use of premedication in adults and children. The marked variation among geographical areas in premedicant usage patterns under-scores the lack of consensus among anesthesiologists about the need for premedication. The data suggest that HMO participation may affect delivery of this component of anesthetic care. (Anesth Analg 1997;84:427-32)

Predictors of postoperative respiratory complications in premature infants after inguinal herniorrhaphy

There is a significant incidence of inguinal hernia in premature infants and the optimal timing of repair is controversial. A high rate of postoperative respiratory complications has been reported in this group. In this study, the records of 47 premature infants (mean gestational age, 30.3 weeks) who underwent herniorrhaphy while still in the neonatal intensive care unit were reviewed in an effort to define those conditions that are independent risk factors for complications. Forty-three percent of infants had complications, including postoperative assisted ventilation (34%), episodes of apnea and/or bradycardia (23%), emesis and cyanosis with first feeding (6%), and requirement for postoperative reintubation (4%). Although low gestational age and postconceptual age at operation, low birth weight for gestational age, and preoperative ventilatory assistance were significantly associated with postoperative complications, only a history of respiratory distress syndrome/bronchopulmonary dysplasia (odds ratio 2.3), a history of patent ductus arteriosus (odds ratio 2.5), and low absolute weight at operation (odds ratio 3.5 for 1,000-g decrease) were independent risk factors for postoperative complication. Despite previous reports citing postconceptual age as the factor having the greatest impact on postoperative complications, these results indicate that a history of respiratory dysfunction and size at operation may be more important predictors of postoperative respiratory dysfunction in preterm infants.

Effect of peripheral perfusion on accuracy of pulse oximetry in children.

STUDY OBJECTIVE To examine the effect of perfusion on accuracy of two pulse oximeters in children and to determine thresholds of perfusion below which these pulse oximeters become inaccurate or cease to function. DESIGN Prospective, observational clinical study. SETTING Operating room of a large university hospital. PATIENTS 19 children 10 years of age or less, who were scheduled for general anesthesia with placement of an intraarterial catheter. INTERVENTIONS A radial artery catheter, laser Doppler probe, skin temperature sensor, and band probes of two oximeters, Ohmeda 3700 (Boulder, CO) and Nellcor N200 (Hayward, CA), were attached to the same hand. Baseline pulse oximeter and Doppler readings were obtained with simultaneous hemoximetry (AVL Model 912 CO-Oxylite, Roswell, GA), skin and esophageal temperatures, total hemoglobin, and transduced arterial pressure. Readings of all parameters (n = 94) were obtained during periods of low perfusion or by occluding the upper arm to 70% to 100% of systolic pressure. MEASUREMENTS AND MAIN RESULTS Bias (SpO2-SaO2) of each oximeter is compared to each perfusion variable (age, weight, core and skin temperature, hemoglobin concentration, pulse pressure, and percent flow by laser Doppler) to determine effect on accuracy. Data were analyzed using backward multivariate linear regression, Pearson correlation coefficients, and independent paired t-test. p < 0.05 was considered significant. Less than 2% bias is seen with either oximeter (Nellcor 1.55 +/- 2.33, Ohmeda 0.78 +/- 2.25). Independent predictors of bias for each machine include weight (r = -0.376; p < 0.001) and pulse pressure (r = 0.250; p = 0.021) for the Nellcor, and weight (r = -0.390; p < 0.001), percent flow by Doppler (r = 0.220; p = 0.035), and core temperature (r = 0.307; p = 0.003) for the Ohmeda. However, using predetermined thresholds for each variable, only skin temperature below 30 degrees C is identified as a significant predictor of oximeter inaccuracy. CONCLUSIONS At the parameters explored in this study, the selected seven perfusion variables (age, weight, core and skin temperature, hemoglobin concentration, pulse pressure, and percent flow by laser Doppler) have little effect on accuracy of pulse oximetry in children.

Pneumothorax in drug abusers: A complication of internal jugular venous injections

We report the cases of six patients who suffered pneumothorax following admitted drug injection into the internal jugular vein area. One was treated in the hospital with observation and serial roentgenograms, two were treated with chest tube thoracostomy, and three left the emergency department against medical advice and were lost to follow up. As increasing numbers of parenteral addicts turn to central venous injection sites, this complication is likely to become more common.

Effect of probe design on accuracy and reliability of pulse oximetry in pediatric patients

Abstract Study Objective: To determine if the traditional band-wrap disposable pulse oximeter probe is more accurate or reliable for oxygen monitoring in children than the reusable clip-type probe. Design: Prospective, observational clinical study. Setting: Operating room of a large university hospital. Patients: 18 children 11 years of age or younger, who were scheduled for general anesthesia with placement of an intraarterial catheter. Interventions: Pulse oximetry values were obtained using both band and clip probes of three pulse oximeters (Nellcor, Hayward CA; Novametrix, Wallingford, CT; Ohmeda, Boulder, CO) and compared with simultaneous hemoximetry values. Dropout rate (percent of down time) also was recorded for each probe-machine combination. Measurements and Main Results: Data were analyzed using bias and precision and t -test. p 2 − SaO 2 ) is less than 2% for all probe-machine combinations. The range of error observed between SpO 2 and SaO 2 for all data points was greatest using the Nellcor band (27.8%) and least using the Ohmeda band (11.4%). In cyanotic children, the greatest bias and precision were observed with Nellcor band (N = 11, −5.12 ± 9.74) and the best agreement with Novametrix band (N = 17, 0.08 ± 4.21). The difference in bias for any test units above or below the median weight of 13.75 kg did not vary by more than 1%. Dropout rate was minimal for all units in nonbypass situations. After cardiopulmonary bypass, no data dropout was observed with Ohmeda band; observed down time with the other units varied between 34% and 55%. Conclusions: The type of probe selected has little effect on accuracy of pulse oximetry in children. After cardiopulmonary bypass, using the Ohmeda band combination may improve the likelihood of obtaining consistent readings and decreasing down time.

Monitoring oxygenation and ventilation during magnetic resonance imaging: A pictorial essay

Three types of energy are encountered during magnetic resonance (MR) scans, resulting in a hostile environment for much of the equipment and monitoring devices that have become the standard for anesthetic care. A static magnetic field of 1.5 Tesla within the bore of the scanner is roughly 15,000 times greater than the magnetic field of the earths surface. Within this field, ferromagnetic devices can become airborne, damaging equipment and/ or the scanner, or injuring the patient. Radio-frequency (RF) and time-varied magnetic fields, which can interfere with standard monitors, are also used. Parts of anesthesia equipment can function like an antenna, interfering with the RF and degrading the image. Because of these factors, all devices used in the M R suite must meet the following criteria: they must function normally within the suite, they must pose no danger to the patient or to personnel, and they must have no effect on imaging. Although monitoring oxygenation and ventilation is required by both the American Society of Anesthesiologists and the American Academy of Pediatrics as standard during general anesthesia or sedation, it is nevertheless challenging to meet these standards within the magnetic resonance imaging (MRI) suite. Several modalities for monitoring the adequacy of ventilation are described below. It is often most effective to incorporate several techniques during scanning, as one system or another may yield more information at different times.