Use of cuffed endotracheal tubes in infants less than 5 kilograms: A retrospective cohort study.

BACKGROUND: Improved understanding of airway anatomy and refinement of equipment have led to the increased use of cuffed endotracheal tubes (ETTs) in infants and children. Despite expanded evidence on the potential advantages of cuffed ETTs in pediatric patients, there remains limited data on their use in infants less than 5 kilograms (kg). The current study retrospectively evaluates the perioperative use of cuffed ETTs in infants weighing 2-5 kg. METHODS: This is a retrospective study from a tertiary care children's hospital involving a 3-year period. Data regarding anesthetic care, airway management, and postoperative course were retrospectively retrieved from the electronic medical record. RESULTS: The study cohort included 1162 patients, 1086 of whom had their tracheas intubated with a cuffed ETT and 76 with an uncuffed ETT. Patients were divided into two groups for analysis: 2 to <3 kg and 3 to 5 kg. In both weight groups, cuffed ETTs resulted in a decreased need for more than one laryngoscopy and a change in ETT size with no increase in postoperative airway effects including stridor. CONCLUSIONS: These data provide additional information regarding the efficacy and safety of cuffed ETTs in neonates and infants.

Variations in stability revealed by temporal asymmetries in contraction of phase space flow.

Empirical diagnosis of stability has received considerable attention, often focused on variance metrics for early warning signals of abrupt system change or delicate techniques measuring Lyapunov spectra. The theoretical foundation for the popular early warning signal approach has been limited to relatively simple system changes such as bifurcating fixed points where variability is extrinsic to the steady state. We offer a novel measurement of stability that applies in wide ranging systems that contain variability in both internal steady state dynamics and in response to external perturbations. Utilizing connections between stability, dissipation, and phase space flow, we show that stability correlates with temporal asymmetry in a measure of phase space flow contraction. Our method is general as it reveals stability variation independent of assumptions about the nature of system variability or attractor shape. After showing efficacy in a variety of model systems, we apply our technique for measuring stability to monthly returns of the S&P 500 index in the time periods surrounding the global stock market crash of October 1987. Market stability is shown to be higher in the several years preceding and subsequent to the 1987 market crash. We anticipate our technique will have wide applicability in climate, ecological, financial, and social systems where stability is a pressing concern.