Article Text

Download PDFPDF
Asleep Versus Awake: Does It Matter?
  1. Andreas H. Taenzer, MD, MS*,
  2. Benjamin J. Walker, MD,
  3. Adrian T. Bosenberg, MBChB, FFA(SA),
  4. Lynn Martin, MD,
  5. Santhanam Suresh, MD§,
  6. David M. Polaner, MD, FAAP,
  7. Christie Wolf, MBS# and
  8. Elliot J. Krane, MD**
  1. *Departments of Anesthesiology and Pediatrics, Children’s Hospital at Dartmouth, Lebanon, and The Geisel School of Medicine at Dartmouth, Hanover, New Hampshire
  2. Department of Anesthesiology, University of Wisconsin School of Medicine and Public Health, American Family Children’s Hospital, Madison, Wisconsin
  3. Department of Anesthesiology & Pain Medicine, University of Washington, and Seattle Children’s Hospital, Seattle, Washington
  4. §Department of Pediatric Anesthesiology, Ann & Robert H. Lurie Children’s Hospital of Chicago, Northwestern University, Chicago, Illinois
  5. Departments of Anesthesiology and Pediatrics, Children’s Hospital of Colorado, University of Colorado School of Medicine, Aurora, Colorado
  6. #Axio Research, Seattle, Washington
  7. **Department of Anesthesiology, Pain and Perioperative Medicine, The Lucile Packard Children’s Hospital at Stanford, Stanford University, Stanford, California
  1. Address correspondence to: Andreas H. Taenzer, MD, MS, Dartmouth Hitchcock Medical Center, Department of Anesthesiology, One Medical Center Dr, Lebanon, NH 03756 (e-mail: andreas.h.taenzer{at}


Background and Objectives The impact of the patient state at time of placement of regional blocks on the risk of complications is unknown. Current opinion is based almost entirely on case reports, despite considerable interest in the question. Analyzing more than 50,000 pediatric regional anesthesia blocks from an observational prospective database, we determined the rate of adverse events in relation to the patient’s state at the time of block placement. Primary outcomes considered were postoperative neurologic symptoms (PONSs) and local anesthetic systemic toxicity (LAST). Secondary outcome was extended hospital stay due to a block complication.

Methods The Pediatric Regional Anesthesia Network is a multi-institutional research consortium that was created with an emphasis on rigorous, prospective, and complete data collection including a data validation and audit process. For the purpose of the analysis, blocks were divided in major groups by single injection versus continuous and by block location. Rates were determined in aggregate for these groups and classified further based on the patient’s state (general anesthesia [GA] without neuromuscular blockade [NMB], GA with NMB, sedated, and awake) at the time of block placement.

Results Postoperative neurological symptoms occurred at a rate of 0.93/1000 (confidence interval [CI], 0.7–1.2) under GA and 6.82/1000 (CI, 4.2–10.5) in sedated and awake patients. The only occurrence of PONSs lasting longer than 6 months (PONSs-L) was a small sensory deficit in a sedated patient (0.019/1000 [CI, 0–0.1] for all, 0.48/1000 [CI, 0.1–2.7] for sedated patients). There were no cases of paralysis. There were 5 cases of LAST or 0.09/1000 (CI, 0.03–0.21). The incidence of LAST in patients under GA (both with and without NMB) was 0.08/1000 (CI, 0.02–0.2) and 0.34/1000 (CI, 0–1.9) in awake/sedated patients. Extended hospital stays were described 18 times (0.33/1000 [CI, 0.2–0.53]). The rate for patients under GA without NMB was 0.29/1000 (CI, 0.13–0.48); GA with NMB, 0.29/1000 (CI, 0.06–0.84); sedated, 1.47/1000 (CI, 0.3–4.3); and awake, 1.15/1000 (CI, 0.02–6.4).

Conclusions The placement of regional anesthetic blocks in pediatric patients under GA is as safe as placement in sedated and awake children. Our results provide the first prospective evidence for the pediatric anesthesia community that the practice of placing blocks in anesthetized patients should be considered safe and should remain the prevailing standard of care. Prohibitive recommendations based on anecdote and case reports cannot be supported.

Statistics from

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.


  • The authors declare no conflict of interest.