Newsmaker Interview

Literature Review:
Propofol sedation: intensivists’ experience with 7304 cases in a children’s hospital

Point of Interest

Literature Review

Vespasiano M, Finkelstein M, Kurachek S.  Propofol sedation: intensivists’ experience with 7304 cases in a children’s hospital.  Pediatrics 2007; 120:e1411-e1417.

Abstract:
Objective:  The objective of this study was to determine the safety profile of propofol as a deep-sedation agent in a primarily outpatient program consisting of pediatric critical care physicians and specifically trained nurses with oversight provided by anesthesiology.  One hypothesis was investigated:  adverse events and/or airway interventions are more likely to occur in children with an abnormal airway score. 

Methods:  A 36-month dual-site prospective, observational, clinical study was conducted in a single center with interchangeable providers operating within the guidelines of a single sedation program.  A total of 7304 propofol sedations for 4464 unique patients who ranged in age from 1 month to 21 years were studied; >97% of the children were >1 year of age. 

Results:  The following adverse reactions were identified, and a descriptive statistical analysis of the data were performed: mild oxygen desaturation (85%-90%), 1.73%; serious oxygen desaturation (<85%), 2.9%; laryngospasm, 0.27%; regurgitation without aspiration, 0.05%; regurgitation with aspiration, 0.01%; bronchospasm, 0.15%; and hypotension, 31.4%.  Interventions required included oral airway, 0.96%; nasal trumpet, 1.57%; rescue breaths for >1 minute, 0.37%; intubation, 0.03%; volume requirement of >40 mL/kg per hour, 0.11%; sedation-induced ward or PICU admission, 0.04%; cardiac arrest medications, 0%; and aborted sedation or procedure, 0%.  We devised an airway score to identify at-risk patients.  Patients with an abnormal airway score were significantly more likely to: have oxygen desaturation (13.1% vs 4.3%); require an oral airway (5.9% vs 0.8%); and require a nasal trumpet (13.9% vs 1.2%). 

Conclusions:  Propofol has an acceptable safety profile for deep sedation when used in the context of a program with critical care physicians, specifically trained nurses, and anesthesiology oversight.  A preprocedure airway score can assist in identifying patients who may require airway interventions.

Comment:  This article provides the largest single center study evaluating the use of propofol for procedural sedation in children to date.  The study was a prospective evaluation with two primary goals – to report on the safety profile of propofol as a deep sedative agent in children, and to evaluate the effectiveness of a basic screening airway score in identifying children at increased risk for complications.  All children needing deep sedation were eligible for inclusion.  Children were only excluded if they had an acute illness that precluded any sedation or if they had a condition that warranted care by anesthesiology.  Propofol was used as the sole agent in the majority of sedations (author (M.V.) communication).  As the authors point out, it would have been instructive to know how many children were referred to anesthesiology and for what indications.  Adverse events and their incidences are as described in the abstract.  Of note, the patient pool in this sample is just large enough to approach adequate power to evaluate safety in terms of these events and their interventions.  These outcomes roughly parallel those in the review of approximately 50,000 propofol sedation encounters from the PSRC database that has recently been submitted for publication.

In looking more closely at the complications and outcomes, three children required hospital admission, two who required endotracheal intubation and one who experienced laryngospasm.  The two intubations occurred in the early phases of the study in airway class 2 patients (see explanation below) less than 2 months of age. Both patients had a history of prematurity and chronic lung disease, and both developed apnea after their induction dose of propofol for MRI scanning. According to one of the authors (M.V.), these patients would now be referred directly to anesthesia.   Three children vomited during their sedation, and one of these children was subsequently diagnosed with aspiration. All patients with regurgitation were airway class 2 and had met NPO guidelines.   The incidence of hypotension, defined as a decrease in systolic blood pressure of ≥25 mm Hg from baseline or from a “normal” blood pressure for age (considered separately if the initial blood pressure measurement was felt to be falsely elevated due to anxiety) was notably high at 31.4%.  Due to the variability in defining hypotension in the literature, this study provides the largest body of evidence that blood pressure does fall substantially with propofol use.  It remains unclear if this hypotension has any clinical ramifications.  The authors comment that, “propofol-induced hypotension seems to be transient and of little physiologic relevance in the relatively healthy child who remains well perfused with peripheral warmth and excellent capillary refill during a sedation intervention.”  However, 8 patients received volume at >40 mL/kg/hour and 6 patients received fluid resuscitation via hand pushing volume. The trigger for a fluid bolus was primarily physician specific. Interestingly, fluid administration was typically not accompanied by an increase in blood pressure (author communication). 

The development of an objective pre-sedation airway score that could be used to determine the likelihood of subsequent airway complications during deep sedation was the second major objective of the study.  As a first step, patients were assigned an “airway score” based on the absence or presence any one of several “red flag” items in a screening history.  Patients were labeled as having a “class 1 airway” if they had no historical features that seemed to place them at increased risk for airway compromise during sedation.  Risk factors that earned patients a “class 2 airway” designation included: current stridor, snoring, obstructive sleep apnea, morbid obesity, craniofacial malformation, symptomatic asthma or heart disease, GERD, swallowing dysfunction, and/or previous airway problems with sedation or anesthesia.  Of the 7304 sedations, only 237 received the class 2 airway designation.  These patients had a statistically higher incidence of desaturation during the sedation as well as of requirement for oral airway or nasal trumpet intervention.  Clearly, given the low incidence of more significant airway complications such as need for endotracheal intubation and laryngospasm, this study does not have adequate statistical power to evaluate correlation between airway score and these events.  This study is the first to assess deep sedation risk by use of an airway screening score.  We agree that reviewing these risks with families prior to the sedation visit could minimize the number of children who end up getting referred to anesthesia at the last minute and also could serve as a reminder in screening these children to review such risks with their families.  Also, any system that reminds providers of the airway risks involved with managing deeply sedated patients, even if these risks seem intuitive, can’t be a bad idea.  Further correlation of increased airway scores with untoward events will require a larger study sample and perhaps a more robust scoring system with greater breakdown in patient categories.

Editors:
Joseph Cravero MD
George Blike MD

Departments of Anesthesiology
and Pediatrics,
Children’s Hospital
at Dartmouth,
Dartmouth Hitchcock
Medical Center,
Lebanon, NH

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