Articles from Anesthesia & Analgesia

Link to journal online
O'Connor, Maeve; Coleman, Margaret ;Wallis, Fintan; Harmon, Dominic
An Anatomical Study of the Parasacral Block Using Magnetic Resonance Imaging of Healthy Volunteers.
Anesthesia & Analgesia. 108(5):1708-1712, May 2009.
Abstract
BACKGROUND: The parasacral approach to sciatic blockade is reported to be easy to learn and perform, with a high success rate and few complications.METHODS: Using magnetic resonance imaging, we evaluated the accuracy of a simulated needle (perpendicular to skin) in contacting the sacral plexus with this approach in 10 volunteers. Intrapelvic structures encountered during the simulated parasacral blocks were also recorded.RESULTS: The sacral plexus was contacted by the simulated needle in 4 of the 10 volunteers, and the sciatic nerve itself in one volunteer. The plexus was accurately located adjacent to a variety of visceral structures, including small bowel, blood vessels, and ovary. In the remaining five volunteers (in whom the plexus was not contacted on first needle pass), small bowel, rectum, blood vessels, seminal vesicles, and bony structures were encountered. Historically, when plexus is not encountered, readjustment of the needle insertion point more caudally has been recommended. We found that such an adjustment resulted in simulated perforation of intrapelvic organs or the perianal fossa.CONCLUSIONS: These findings question the reliability of the anatomical landmarks of the parasacral block and raise the possibility of frequent visceral puncture using this technique


Wachtel, Ruth E. ; Dexter, Franklin ; Dow, Angella J.
Growth Rates in Pediatric Diagnostic Imaging and Sedation.
Anesthesia & Analgesia. 108(5):1616-1621, May 2009.
Abstract
BACKGROUND: Workload has increased greatly over the past decade for anesthesia providers administering general anesthesia and/or sedation for pediatric diagnostic imaging.METHODS: Data from an academic medical center were studied over a 12-yr period. Growth in the number of children 0-17 yr of age undergoing magnetic resonance imaging (MRI) and/or computerized tomography (CT) scans who received care from anesthesia providers was compared with the increase in the total number of MRI and CT procedures performed in children. Anesthesia providers included anesthesiologists, residents, Certified Registered Nurse Anesthetists, and student Certified Registered Nurse Anesthetists. Toward the end of the study, a team of sedation nurses was employed by the hospital to administer moderate sedation. They provided an alternative to anesthesia providers from the anesthesia department, who usually administered general anesthesia. Use of sedation nurses versus anesthesia providers, and the relationship to scan duration and patient age, were studied over a 6-mo period.RESULTS: The number of children receiving care from anesthesia providers for MRI and CT scans grew at the same 8%-9% annual rate as the number of scans performed. The percentage of children receiving anesthesia care did not change over the 12 yr. Creation of a nurse sedation team that provided moderate sedation did not alter the number of children receiving care from anesthesia providers but did increase the total number of children receiving hypnotics. Anesthesia was rarely used for scans shorter than 30 min in duration. Increases in scan duration were associated with increased utilization of anesthesia providers for both MRI and CT after stratifying by age. An age of 3-5 yr was associated with the highest rates of anesthesia care.CONCLUSIONS: Future workload for anesthesia providers administering general anesthesia and/or sedation for pediatric diagnostic imaging will depend on trends in the total number of scans performed. Workload may also be sensitive to factors that increase scan duration or alter the percentage of patients in the 3-5 yr age group. It may additionally depend on reimbursements from insurance companies.

Citation 7.
Accession Number
00000539-200906000-00026.
Author
Balki, Mrinalini MBBS, MD *; Lee, Yung MD *; Halpern, Stephen MD, MSc, FRCPC +; Carvalho, Jose C. A. MD, PhD, FANZCA, FRCPC *;
Institution
From the *Department of Anesthesia and Pain Management, Mount Sinai Hospital, and +Department of Anesthesia, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada.
Title
Ultrasound Imaging of the Lumbar Spine in the Transverse Plane: The Correlation Between Estimated and Actual Depth to the Epidural Space in Obese Parturients.[Miscellaneous Article]
Source
Anesthesia & Analgesia. 108(6):1876-1881, June 2009.
Abstract
BACKGROUND: Prepuncture lumbar ultrasound scanning is a reliable tool to facilitate labor epidural needle placement in nonobese parturients. In this study, we assessed prepuncture lumbar ultrasound scanning as a tool for estimating the depth to the epidural space and determining the optimal insertion point in obese parturients.METHODS: We studied 46 obese parturients, with prepregnancy body mass index (BMI) >30 kg/m2, requesting labor epidural analgesia. Ultrasound imaging was done by one of the investigators to identify the midline, the intervertebral space, and the distance from the skin to the epidural space (ultrasound depth, UD) at the level of L3-4. Subsequently, an anesthesiologist blinded to the UD located the epidural space through the predetermined insertion point and marked the actual distance from the skin to the epidural space (needle depth, ND) on the needle with a sterile marker. The agreement between the UD and the ND was calculated using the Pearson correlation coefficient and a paired t-test. Bland-Altman analysis was used to determine the 95% limits of agreement between the UD and the ND.RESULTS: The prepregnancy BMI ranged from 30 to 79 kg/m2, and the BMI at delivery was 33-86 kg/m2. The Pearson correlation coefficient between the UD and the ND was 0.85 (95% confidence interval: 0.75-0.91), and the concordance correlation coefficient was 0.79 (95% confidence interval: 0.71-0.88). The mean (+/-sd) ND and UD were 6.6 +/- 1.0 cm and 6.3 +/- 0.8 cm, respectively (difference = 0.3 cm, P = 0.002). The 95% limits of agreement were 1.3 cm to -0.7 cm. Epidural needle placement using the predetermined insertion point was done without reinsertion at a different puncture site in 76.1% of parturients and without redirection in 67.4%.CONCLUSIONS: We found a strong correlation between the ultrasound-estimated distance to the epidural space and the actual measured needle distance in obese parturients. We suggest that prepuncture lumbar ultrasound may be a useful guide to facilitate the placement of epidural needles in obese parturients.(C) 2009 by International Anesthesia Research Society.