Literature Reviews

Major Adverse Events and Relationship to Nil per Os Status in Pediatric Sedation/Anesthesia Outside the Operating Room

Langhan ML, Shanbanova V, Fang-Yong L, Bernstein SL and Shapiro ED.  American Journal of Emergency Medicine.  2015 January 30; 33(1); 25-30.

Reviewed by: Carmen D. Sulton, MD
Assistant Professor of Pediatrics and Emergency Medicine
Emory University School of Medicine
Atlanta, GA

Laurie Burton, MD
Assistant Professor of Pediatrics and Emergency Medicine
Emory University School of Medicine
Atlanta, GA

Pradip Kamat, MD, MBA, FCCM
Associate Professor of Pediatrics
Emory University School of Medicine
Director Children’s Sedation services at Egleston
Atlanta, GA

Jason Reynolds, MD
Assistant Professor of Pediatrics
Section of Pediatric Sedation
Baylor College of Medicine
San Antonio, TX

Patricia Scherrer, MD
Associate Professor of Pediatrics
Section of Pediatric Sedation
Baylor College of Medicine
San Antonio, TX

The relationship between nil per os (NPO) status and serious events during pediatric procedural sedation is often the subject of research and debate.  Aspiration, specifically, is of particular interest.  However, aspiration events in pediatrics are quite rare which has made examining the risk factors and associated events challenging. 

This study by Beach et al examined approximately 140,000 sedation encounters to evaluate the link between patient/procedure demographic factors and NPO interval.  Data was collected from the Pediatric Sedation Research Consortium (PSRC) using its well documented and on-line data collection tool.  This tool gathers a report of “complications during procedure.”  A “major adverse event” was defined as aspiration, death, cardiac arrest, or unplanned hospital admission. 

Specifically, aspiration was defined as an event where emesis was noted or food material was found in the oral/pharyngeal cavity, and associated with any of the following: new cough, wheeze, increased respiratory effort, and change in chest radiograph indicative of aspiration or new need for oxygen therapy after recovery from sedation.  The primary outcomes were NPO interval and the relationship with aspiration events and major adverse events (AE).  NPO status was defined as no solid food for >8 hours, no non-clear fluids for >6 hours and no clear fluids for at least two hours.

The results showed that the most commonly sedated procedure included Magnetic Resonance Imaging (MRI) and Computerized Tomography (CT) scans, followed by oncologic procedures involving lumbar punctures.  Of the 140,000 sedation encounters, approximately 82,500 patients were documented as NPO, ~25,400 were documented as not NPO and in ~31,000 cases the NPO status was unknown.  Propofol was the most commonly administered sedation agent.  Of the sedated patients documented as NPO who received sedation, there were only eight reported cases of aspiration and 46 reported major AE.  Of the ~25,400 patients documented not to be NPO who received sedation, there were only two reported aspiration cases and 14 reported major AE.  For those sedated patients that were not NPO and had aspiration and/or AE, most had NPO violations for solids.  There were no statistically significant association between NPO status and major AE.  Of patients where NPO status was known, having a gastrointestinal diagnosis or a diagnosis of obstructive sleep apnea was associated with higher complication rates. 

Additionally, having an airway procedure, such as bronchoscopy was also associated with a sedation higher complication rate.  After controlling for age, American Society of Anesthesiologists physical status greater than II, propofol use, provider type and emergent status there remained no statistically significant association between major AE and NPO status.  However, there were simply too few aspiration events to complete the same multivariate analysis.  Notably, infants had 3-fold higher risk of a major complication (OR 3.01, 95% CI 1.45-6.50).  

A notable limitation in this study is that the NPO data is missing for ~31,000 cases.  However, the authors make a clear case that of the 14 cases in the “NPO unknown” group where a major event was recorded, at least 10 (71%) would need to have violated NPO guidelines to be statistically significant.  This high rate of violating NPO seems unlikely, given the trend of ~23% of sedated patients who were known to have violated NPO guidelines in the non-missing data.  Additionally, the data used are pulled from a database where there is no control group.  Thus, directly determining cause and effect is challenging.

Has the time come to re-evaluate NPO guidelines and standards?

There are a number of NPO guidelines provided by a number of governing societies, including the American Society of Anesthesiology (ASA) and the American College of Emergency Physicians (ACEP).  The authors specifically make the point that NPO guidelines were created, in general, for elective procedures.  However, the direct relationship between NPO status and aspiration remains unclear.  With regards to urgent and emergent procedures, a review of the 2014 Procedural Sedation Guidelines by ACEP state that procedural sedation should not be delayed in the emergency setting in adults or pediatrics, based on fasting time alone. The authors also reference an article by Roback et al which discusses ~2,500 sedation encounters specifically in the emergency department.  Most were ketamine sedations.  No endotracheal intubations and no aspirations were reported.  However, It is clear that certain disease processes and patient risk factors must be considered and may be of more significance than NPO status alone.  More research is needed in this area in the future.

The article abstract can be found via the link on our blog, www.pedzzzz.com.

References:

  1. Beach, ML, Cohen DM, Gallagher SM, and Cravero JP. "Major Adverse Events and Relationship to Nil per Os Status in Pediatric Sedation/Anesthesia Outside the Operating Room." Anesthesiology. 124.1 (2016): 80-88. 
  2. Godwin SA, Burton JH, Gerardo CJ, Hatten BW, Mace SE, Silvers SM, and Fesmire FM. "Clinical Policy: Procedural Sedation and Analgesia in the Emergency Department." Annals of Emergency Medicine 63.2 (2014).
  3. Roback, MG, Wathen JE, Bajaj L, and Bothner JP. "Adverse Events Associated with Procedural Sedation and Analgesia in a Pediatric Emergency Department: A Comparison of Common Parenteral Drugs." Academic Emergency Medicine 12.6 (2005): 508-13.

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