Clinical Anesthesiology


Procedural Sedation More Complicated in Obese Children

by Kate O’Rourke

Obese children who undergo procedural sedation are at an increased risk for adverse events including respiratory problems, a recent study has found.

“If you are going to give procedural sedation to children, your risk for needing to provide airway repositioning, airway adjuncts and bag mask ventilation, and of running into airway complications, is higher if the child is obese,” said Patricia Scherrer, MD, medical director of sedation services at Children’s Hospitals and Clinics of Minnesota.

Dr. Scherrer’s group presented its findings at the 2012 annual meeting of the Society for Critical Care Medicine (abstract 831).

Peter Davis, MD, chief anesthesiologist at Children’s Hospital of Pittsburgh, said the study “goes along with the trend that being obese is detrimental to your health.” Researchers have shown that obesity complicates anesthesia and procedural sedation in adults, but this is the first time a study demonstrated that obesity adversely affects procedural sedation in a pediatric population. “It hasn’t been documented in children before, but it is not a surprising finding,” said Dr. Davis, a member of the Anesthesiology News editorial board.

Dr. Scherrer and colleagues queried the database of the Pediatric Sedation Research Consortium (PSRC), a conglomerate that has included between 28 and 35 institutions at any given time. Founded in 2001, the consortium prospectively enrolls and collects demographic and procedural information for all pediatric sedation procedures performed at centers in the PSRC. The database is housed at the Dartmouth Bioinformatics Service Center, in Lebanon, N.H.

The investigators identified 28,792 patients in the PSRC whose body mass index (BMI) index could be calculated. They compared sedation-related outcomes, adverse events and required interventions for obese and non-obese patients. To be considered obese, patients had to fall in the 95th percentile or above in terms of BMI.

Roughly three-fourths of the patients received propofol, either as a single agent or in combination with an analgesic. Other sedatives included chloral hydrate, dexmedetomidine (Precedex, Hospira), diazepam, etomidate, ketamine, methohexital (Brevital, JHP Pharmaceuticals), midazolam, pentobarbital and thiopental.

Adverse events overall were more prevalent in obese patients (6.1% vs. 4.1%; P<0.001), with small increases in airway obstruction (2.1% vs. 1.1%; P<0.005), oxygen desaturation (1.3% vs. 0.7%; P<0.005), laryngospasm (0.4% vs. 0.2%; P<0.005), prolonged sedation/recovery events (0.35% vs. 0.13%; P<0.05) and sedation failures (0.39% vs. 0.2%; P<0.05).

Although the relative increase for many of these complications was large, their absolute incidence was low. For example, the increase in laryngospasm doubled from 0.2% to 0.4%, but the complication occurred in only one of 250 of the children who were obese. According to Dr. Scherrer, however, “in terms of the overall number of pediatric patients who have received procedural sedation in the United States around the country, it ends up being a substantial number of patients.”

In a multivariate logistic regression analysis, patients who were obese were more likely to have minor complications (odds ratio [OR], 1.28; 95% confidence interval [CI], 1.15-1.54) and moderate events (OR, 1.83; 95% CI, 1.51-2.21). No difference was identified for major adverse events.

Airway interventions were more common in obese than in non-obese patients, including repositioning (40.5% vs. 34.3%), jaw thrust (22.1% vs. 17%), suctioning (16.3% vs. 13.2%), placement of an airway (15.8% vs. 12.1%) and bag/valve/mask ventilation (4.2% vs. 3.4%) (P<0.01 for all).

John Devlin, PharmD, associate professor of pharmacy at Northeastern University, in Boston, said it is important to consider whether the effect of obesity on the pharmacokinetic properties of the sedatives administered leads to the higher incidence of sedation failure and longer sedation recovery in obese patients.

“For example, a sedative like midazolam is distributed widely in fat, having a high volume of distribution. Therefore, administering a dose of midazolam based on ideal body weight—not accounting for the distribution into fat—could lead to sedation failure,” Dr. Devlin said. “Conversely, administering a dose of sedative with a lower volume of distribution, like dexmedetomidine, using an obese child’s actual body weight could lead to a longer period for sedation recovery.”

Information on whether doctors used ideal, adjusted or actual body weight when dosing patients would have been helpful in interpreting the study data, he said. Dr. Scherrer said the database does not collect this type of information.

“What we can say to providers who offer procedural sedation for pediatric patients is that you have to think about this increased risk in obese patients,” Dr. Scherrer said. She added that her group did not find any correlation between specific medications that were used and the frequency of adverse events.

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