The American Society of Anesthesiologists’ annual meeting, Anesthesiology 2011, held on October 15-19 in Chicago, was a comprehensive education program in anesthesiology, focusing on transforming patient safety through science and innovation. The news items below highlight just some of the studies that emerged from the meeting.

» Less Propofol Required for Obese Children
» Certain Behaviors Lead to Poor Pediatric Surgical Outcomes 
» Identifying Women at Risk for Cesarean Pain
» Risk Factors for Labor Pain
» Anesthetics & Postoperative Delirium in the Elderly 

Less Propofol Required for Obese Children

The Particulars: The Particulars: Information regarding the appropriate doses for many anesthetics in obese children is lacking. Anesthesiologists must decide whether a dose should be based on actual or lean body weight in a population for whom 75% of excess body weight consists of drug distribution-altering fat tissue. Propofol can cause low blood pressure, prolonged sleepiness, and decreased breathing.

Data Breakdown: Researchers measured responses in 40 obese and 40 non-obese children 20 seconds after they received propofol. To bring about unconsciousness at the beginning of surgery, obese children needed 2 mg/kg of propofol. Normal weight children required 3.2 mg/kg of propofol to bring about unconsciousness.

Take Home Pearl: Obese children appear to require 50% to 60% less propofol than normal weight children to initiate anesthesia at the beginning of surgical procedures.

Certain Behaviors Lead to Poor Pediatric Surgical Outcomes [back to top]

The Particulars: Determining the coping, distress, and anxiety behaviors of children and their parents prior to surgery can be challenging during anesthesia induction and following surgery. The Perioperative Adult Child Behavioral Interaction Scale (PACBIS) is thought to provide real-time measurements for determining the impact of these factors.

Data Breakdown: A study of 405 children aged 3 to 12 undergoing outpatient tonsillectomy and adenoidectomy who were given the PACBIS revealed that high scores on the “child distress” measurement before anesthesia were related to a 6-point increase in emergent delirium when compared with minimal distress. Negative parental behaviors during anesthesia induction increased separation anxiety and sleep disturbances in children. Positive parental behavior was related to decreased maladaptive behaviors like withdrawal and eating disturbances. Children experience a three-fold reduction in pain when parental behavior was positive. Odds of severe pain on Day 1 and Day 7 after surgery increased by 80% when child coping and child distress measurements dropped 2 units.

Take Home Pearls: PACBIS appears to help anesthesiologists identify pre-surgical behaviors in parents and children that lead to negative behaviors following pediatric surgery. Parents who cope well and provide distraction during the perioperative period appear to help reduce the probability of emergent delirium, surgical pain, and maladaptive behaviors experienced by their children.

Identifying Women at Risk for Cesarean Pain [back to top]

The Particulars: Of the approximately 1.4 million cesarean procedures performed each year in the United States, 30% are repeat procedures. Post-cesarean pain is largely undertreated and associated with scar sensitivity and persistent pain. Researchers hypothesized that a high percentage of women undergoing repeat cesarean deliveries suffer from abnormal sensitivity to pain.

Data Breakdown: An analysis of 163 women who were scheduled for repeat cesarean delivery evaluated pain sensitivity with scar mapping and questionnaires. Less than 10% of women recalled persistent pain following their previous cesarean, but 40% of these women had scar hypersensitivity. Higher pain scores were observed in the 2 days after delivery in women with abnormal preoperative scar mapping. The extent of scar sensitivity correlated with pain severity and postoperative pain sensitivity.

Take Home Pearls: Pain testing may help identify deficient pain modulation among women scheduled for repeat cesarean procedures. Such identification may allow for the prevention of unnecessary suffering.

Risk Factors for Labor Pain [back to top]

The Particulars: Many factors can influence labor pain for pregnant women. A mathematical model that quantifies these variables could provide concrete data for use in individualizing pain treatment for mothers in labor.

Data Breakdown: Investigators gathered information on 800 laboring women with regards to ethnicity, age, weight, height, number of previous births, whether labor was induced, number of weeks pregnant, and babies’ weight. At every hour until full cervical dilation, pain scores were recorded. Women younger than 25 and obese women reported higher pain scores after epidural placement than women who were older and had a normal BMI, respectively. Women with longer labors were also at higher risk of pain following epidural placement.

Take Home Pearl: Younger women, those who are obese, and women with longer labor times appear to be at greater risk for pain during labor, even following epidural placement, than other pregnant women.

Anesthetics & Postoperative Delirium in the Elderly [back to top]

The Particulars: Some inhaled anesthetics have been shown in cellular and animal studies to cause alterations in the brain that are similar to those of dementia and Alzheimer’s disease. Research is lacking on the link between anesthesia and postsurgical cognitive decline in humans.

Data Breakdown: Cognitive testing was administered to 200 patients aged 65 or older prior to undergoing major orthopedic surgery in a study. Patients were given opioids with either inhaled isoflurane or intravenous propofol. Of those who received inhaled isoflurane, 12.6% experienced postoperative delirium, compared with 13.6% of those who received intravenous propofol. Researchers determined that preoperative medical conditions and cognitive status affected whether patients would experience delirium. Those who did not experience postoperative delirium had a 5% orthopedic failure rate, compared with a 40% rate for those who did experience delirium.

Take Home Pearls: Preoperative medical issues, executive function, and memory appear to be independent predictors of postoperative delirium. General anesthesia type does not appear to influence delirium incidence among elderly surgical patients.