August 2011

Summer Bulletin Online Now
The Summer issue of our quarterly Bulletin is ONLINE now, with a great article on the pros and cons of closed loop oxygen control, a look at a program aimed at saving the world with soap, and a review of recent section activities.

AARC Congress Online Now
Get the program and travel information you need about the 57th International Respiratory Convention and Exhibition in Tampa. GET PROGRAM

Prolonged Ventilation: What Puts Kids at Increased Risk?
Canadian researchers publishing ahead of print in Pediatric Critical Care Medicine on July 14 have identified several risk factors for prolonged mechanical ventilation in the pediatric population. Their study was conducted among all consecutive episodes of invasive mechanical ventilation occurring in their facility over a one year period. Overall, 360 episodes were identified, 36% of which had a length of ≥96 hours and were defined as prolonged ventilation. Risk factors for prolonged ventilation included age of <12 months, Pediatric Risk of Mortality score of ≥15 at admission, mean airway pressure of ≥13 cm H2O on day 1, use of continuous intravenous sedation on day 1, and use of noninvasive ventilation before intubation. The researchers believe more study is particularly warranted to gauge the impact of sedation protocols on the duration of mechanical ventilation in children. READ ABSTRACT

Lower Back-Up Rates Improve Ventilator Triggering
Australian investigators who set out to determine the effects of various back-up ventilation rates (BURs) on triggered inflations and patient cardiorespiratory stability in 26 stable preterm infants undergoing assist-control/volume guarantee ventilation find a lower BUR allows for greater triggering of ventilator inflations. The infants were assessed at BUR settings of 30, 40, and 50 min.(-1) in a randomized crossover fashion, with results showing a mean proportion of triggered inflations of 85% (11), 75% (19), and 61% (25), respectively, for all comparisons. Total delivered inflation rates were 56 (8), 58 (9), and 62 (8) min.(-1), and no difference was seen between cardiorespiratory parameters, including CO2 levels, at any of the settings. The investigators published their findings ahead of print in the Journal of Perinatology on June 2. READ ABSTRACT

Measuring the Impact of ETT Resistance and Inertance
Since the resistive properties of endotracheal tubes (ETTs) can create high airway flows with excessive flow acceleration in small infants requiring mechanical ventilation, German researchers decided to carry out a model study to investigate the impact of ETT size, lung compliance, and ventilator settings on the pressure-flow characteristics with respect to the resistive and inertive properties of the ETT. Results showed the most relevant factor for a pressure drop was the ETT size, followed by the peak inspiratory pressure, lung compliance, inspiratory time, and PEEP. Gas flow velocity was identified as the common principle for all the parameters. Depending on the ventilator settings, the pressure drop exceeded 8 mbar in the smallest 2.0 mm ETT. The authors suggest “exact tracheal pressure tracings calculated from ventilator readings by applying Rohrer’s equation and the inertance determination to small size ETTs would be helpful.” Integrating this information into the ventilator software would allow for an estimate of the work of breathing and implementation of an automatic tube compensation, and would also help promote gentle ventilation by enabling the physician to estimate consequences of altered ventilator settings at the tracheal level. The study appeared ahead of print in Physiological Measurement on July 28. READ ABSTRACT

Asthmatic Children Living with Smokers Helped by Air Cleaners
Air cleaners are no substitute for a smoke-free home, but for asthmatic children who live with people who continue to smoke, it might be the next best thing. A new study conducted by investigators from Johns Hopkins and funded by the National Institutes of Environmental Health Science, National Institutes of Health, and Environmental Protection Agency found nearly a 50% drop in the level of particulate matter in homes with air cleaners. What’s more, asthmatic children in these homes had significantly more days without asthma symptoms. Using the rate of symptom reduction seen in the study, the authors estimate that a child with asthma living in a home with an air cleaner would likely have 33 more symptom-free days per year when compared with a child living in a home without an air cleaner. No reduction in the level of air nicotine was seen in the homes with air cleaners, and children in these home did not have lower levels of urine cotinine, but since statistics show more than 30% of children in the U.S. share a home with a smoker, and as many as two-thirds of children in urban neighborhoods live with a smoker, the authors believe air cleaners may have a role to play in managing childhood asthma. The study was published in the Aug. 1 edition of the Archives of Pediatric & Adolescent Medicine. READ PRESS RELEASE