Evolution of changes in upper airway collapsibility during slow induction of anesthesia with propofol
MetadataShow full item record
Background: Upper airway collapsibility is known to increase under anesthesia. This study assessed how this increase in collapsibility evolves during slow Propofol induction and how it relates to anesthesia-induced changes in upper airway muscle activity and conscious state. Methods: Nine healthy volunteers were studied. Anesthesia was induced with Propofol in a step-wise manner (effect-site concentration steps of 0.5 µg • ml from 0 to 3 µg • ml and thereafter to 4 µg • ml and 6 µg • ml [target-controlled infusion]). Airway patency was maintained with continuous positive airway pressure. Pharyngeal collapsibility was assessed at each concentration by measuring critical pressure. Intramuscular genioglossus electromyogram and anesthetic depth (bispectral index score) were monitored throughout. Loss of consciousness was defined as failure to respond to loud verbal command. Results: Loss of consciousness occurred at varying Propofol effect-site concentrations between 1.5 and 4.0 µg • ml. Initially genioglossus electromyographic activity was sustained with increases in Propofol concentration, increasing in some individuals. At or approaching loss of consciousness, it decreased, often abruptly, to minimal values with an accompanying increase in critical pressure. In most subjects, bispectral index score decreased alinearly with increasing Propofol concentration with greatest rate of change coinciding with loss of consciousness. Conclusions: Slow stepwise induction of Propofol anesthesia is associated with an alinear increase in upper airway collapsibility. Disproportionate decreases in genioglossus electromyogram activity and increases in pharyngeal critical closing pressure were observed proximate to loss of consciousness, suggesting that particular vulnerability exists after transition from conscious to unconscious sedation. Such changes may have parallels with upper airway behavior at sleep onset. Copyright © 2009, the American Society of Anesthesiologists, Inc.
Showing items related by title, author, creator and subject.
Hillman, D.; Eastwood, Peter (2013)The tendencies to upper airway obstruction during sleep and anesthesia are related. Loss of consciousness in either state increases upper airway collapsibility and anesthesia-related suppression of rousability confers ...
Hillman, D.; Walsh, J.; Maddison, K.; Platt, P.; Schwartz, A.; Eastwood, Peter (2013)Increasing lung volume increases upper airway patency and decreases airway resistance and collapsibility. The role of diaphragm contraction in producing these changes remains unclear. This study was undertaken to determine ...
Numerical simulation of pharyngeal airflow applied to obstructive sleep apnea: effect of the nasal cavity in anatomically accurate airway modelsCisonni, Julien; Lucey, A.; King, A.; Islam, S.; Lewis, R.; Goonewardene, M. (2015)© 2015, International Federation for Medical and Biological Engineering. Repetitive brief episodes of soft-tissue collapse within the upper airway during sleep characterize obstructive sleep apnea (OSA), an extremely ...