TY - JOUR
T1 - Effect of surface tension of mucosal lining liquid on upper airway mechanics in anesthetized humans
AU - Kirkness, J.P.
AU - Eastwood, Peter
AU - Szollosi, I.
AU - Platt, P.R.
AU - Wheatley, J.R.
AU - Amis, T.C.
AU - Hillman, D.R.
PY - 2003
Y1 - 2003
N2 - Upper airway (UA) patency may be influenced by surface tension (gamma) operating within the (UAL). We examined the role of gamma of UAL in the maintenance of UA patency in eight isoflurane-anesthetized supine human subjects breathing via a nasal mask connected to a pneumotachograph attached to a pressure delivery system. We evaluated 1) mask pressure at which the UA closed (Pcrit), 2) UA resistance upstream from the site of UA collapse (RUS), and 3) mask pressure at which the UA reopened (Po). A multiple pressure-transducer catheter was used to identify the site of airway closure ( velopharyngeal in all subjects). UAL samples (0.2 mul) were collected, and the gamma of UAL was determined by using the "pull-off force" technique. Studies were performed before and after the intrapharyngeal instillation of 5 ml of exogenous surfactant ( Exosurf, Glaxo Smith Kline). The gamma of UAL decreased from 61.9 +/- 4.1 ( control) to 50.3 +/- 5.0 mN/m ( surfactant; P < 0.02). Changes in Po, RUS, and Po - Pcrit ( change = control - surfactant) were positively correlated with changes in γ ( r(2) > 0.6; P < 0.02) but not with changes in Pcrit (r(2) = 0.4; P > 0.9). In addition, mean peak inspiratory airflow ( no flow limitation) significantly increased ( P < 0.04) from 0.31 +/- 0.06 ( control) to 0.36 +/- 0.06 l/s ( surfactant). These findings suggest that γ of UAL exerts a force on the UA wall that hinders airway opening. Instillation of exogenous surfactant into the UA lowers the γ of UAL, thus increasing UA patency and augmenting reopening of the collapsed airway.
AB - Upper airway (UA) patency may be influenced by surface tension (gamma) operating within the (UAL). We examined the role of gamma of UAL in the maintenance of UA patency in eight isoflurane-anesthetized supine human subjects breathing via a nasal mask connected to a pneumotachograph attached to a pressure delivery system. We evaluated 1) mask pressure at which the UA closed (Pcrit), 2) UA resistance upstream from the site of UA collapse (RUS), and 3) mask pressure at which the UA reopened (Po). A multiple pressure-transducer catheter was used to identify the site of airway closure ( velopharyngeal in all subjects). UAL samples (0.2 mul) were collected, and the gamma of UAL was determined by using the "pull-off force" technique. Studies were performed before and after the intrapharyngeal instillation of 5 ml of exogenous surfactant ( Exosurf, Glaxo Smith Kline). The gamma of UAL decreased from 61.9 +/- 4.1 ( control) to 50.3 +/- 5.0 mN/m ( surfactant; P < 0.02). Changes in Po, RUS, and Po - Pcrit ( change = control - surfactant) were positively correlated with changes in γ ( r(2) > 0.6; P < 0.02) but not with changes in Pcrit (r(2) = 0.4; P > 0.9). In addition, mean peak inspiratory airflow ( no flow limitation) significantly increased ( P < 0.04) from 0.31 +/- 0.06 ( control) to 0.36 +/- 0.06 l/s ( surfactant). These findings suggest that γ of UAL exerts a force on the UA wall that hinders airway opening. Instillation of exogenous surfactant into the UA lowers the γ of UAL, thus increasing UA patency and augmenting reopening of the collapsed airway.
U2 - 10.1152/japplphysiol.01198.2002
DO - 10.1152/japplphysiol.01198.2002
M3 - Article
SN - 8750-7587
VL - 95
SP - 357
EP - 363
JO - Journal of Applied Physiology
JF - Journal of Applied Physiology
IS - 1
ER -