Transpulmonary pressure gradient and ventilation distribution in excised lungs

Glaister, D. H.; Schroter, R. C.; Sudlow, M. F.; Milic–Emili, J.

doi:10.1016/0034-5687(73)90010-8

Cited by 54 publications

(27 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Lung mechanics. In line with previous results (11,12), during MV with PEEP, there was no evidence of airway closure in open-chest animals, since the static inflation volumepressure curve of the lung was concave to the pressure axis (16), as shown in Fig. 2.…”

Section: Discussionsupporting

confidence: 80%

“…2). When the lower three data points were disregarded, the volume-pressure curve closely fitted (r Ͼ 0.95) a function in the form Vo Ϫ Vx⅐e ϪK ⅐ Ptp , where Vo is maximum volume above resting lung volume, Vx is a volume factor accounting for the rightward shift of the curve due to lung unit recruitment, and K (cmH 2 O Ϫ1 ) is a shape factor that reflects the overall distensibility of the lung (9,16,34). In group Acontrol rabbits, all of these parameters were essentially the same during PEEP1 and PEEP2 (Table 2).…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Effects of mechanical ventilation at low lung volume on respiratory mechanics and nitric oxide exhalation in normal rabbits

D’Angelo¹,

Pecchiari²,

Valle³

et al. 2005

Journal of Applied Physiology

View full text Add to dashboard Cite

. Effects of mechanical ventilation at low lung volume on respiratory mechanics and nitric oxide exhalation in normal rabbits. J Appl Physiol 99: [433][434][435][436][437][438][439][440][441][442][443][444] 2005. First published March 10, 2005; doi:10.1152/japplphysiol.01368.2004, and TNF-␣ in serum and bronchoalveolar lavage fluid were assessed in eight closed and eight open chest, normal anesthetized rabbits undergoing prolonged (3-4 h) mechanical ventilation (MV) at low volume with physiological tidal volumes (10 ml/kg). Relative to initial MV on positive end-expiratory pressure (PEEP), MV at low volume increased lung quasi-static elastance (ϩ267 and ϩ281%), airway (ϩ471 and ϩ382%) and viscolelastic resistance (ϩ480 and ϩ294%), and decreased NOe (Ϫ42 and Ϫ25%) in closed and open chest rabbits, respectively. After restoration of PEEP, viscoelastic resistance returned to control, whereas airway resistance remained elevated (ϩ120 and ϩ31%) and NOe low (Ϫ25 and Ϫ20%) in both groups of rabbits. Elastance remained elevated (ϩ23%) only in closed-chest animals, being associated with interstitial pulmonary edema, as reflected by increased lung wet-to-dry weight ratio with normal albumin concentration in bronchoalveolar lavage fluid. In contrast, in 16 additional closed-and open-chest rabbits, there were no changes of lung mechanics or NOe after prolonged MV on PEEP only. At the end of prolonged MV, TNF-␣ was practically undetectable in serum, whereas its concentration in bronchoalveolar lavage fluid was low and similar in animals subjected or not subjected to ventilation at low volume (62 vs. 43 pg/ml). These results indicate that mechanical injury of peripheral airways due to their cyclic opening and closing during ventilation at low volume results in changes in lung mechanics and reduction in NOe and that these alterations are not mediated by a proinflammatory process, since this is expressed by TNF-␣ levels. lung elastance; interrupter resistance; viscoelasticity; proinflammatory cytokines; exhaled vapor condensate IN AN EX VIVO MODEL OF LAVAGED RAT LUNG, Muscedere et al. (25) showed that ventilation with physiological tidal volumes (VT) from zero end-expiratory pressure (ZEEP) resulted in a significant increase of histological injury scores in the respiratory and membranous bronchioles relative to ventilation from positive end-expiratory pressure (PEEP) above the lower inflection point on the static inflation volume-pressure curve of the lung.

show abstract

Section: Discussionsupporting

confidence: 80%

Section: Resultsmentioning

confidence: 99%

Effects of mechanical ventilation at low lung volume on respiratory mechanics and nitric oxide exhalation in normal rabbits

D’Angelo¹,

Pecchiari²,

Valle³

et al. 2005

Journal of Applied Physiology

View full text Add to dashboard Cite

show abstract

“…In COPD, TODD et al [33] EELV and FRC measurements with helium dilution may be affected by airway closure, which may interfere with correct mixing of helium between the anaesthesia bag and lung [26]. The current authors employed high VTs (1.0-1.5 L), which resulted in PL .20 cmH 2 O and probable re-opening of closed airways [26,34,35]. Low respiratory rates were also used, which resulted in a prolonged expiratory time of ,12 s, in order to augment expiratory helium mixing between anaesthesia bag and lung and minimise helium trapping.…”

Section: Prone Position and Airway Resistance In Copd Sd Mentzelopomentioning

confidence: 96%

Prone position improves expiratory airway mechanics in severe chronic bronchitis

Mentzelopoulos¹

2005

European Respiratory Journal

View full text Add to dashboard Cite

Based on lung parenchyma-airways' interdependence, the present authors hypothesised that prone positioning may reduce airway resistance in severe chronic bronchitis.A total of 10 anaesthetised/mechanically ventilated patients were enrolled. Partitioned respiratory system (RS) mechanics during iso-flow experiments (flow50.91 L?s In severe chronic bronchitis, prone positioning reduces airway resistance and dynamic hyperinflation.

show abstract

“…Glaister et al [3] suggested that the on set of closing volume coincides with the point of inflection in the deflation PV curve of the lung. This point is where the shape of the curve changes from being concave to convex relative to the pressure axis.…”

Section: Introductionmentioning

confidence: 99%

“…Closure of some lung units should lead to simultaneous decrease in the compliance of the whole lung [2]. There fore, the onset of closure of significant pro portion of small airways should be accom panied by decrease in the slope of the pres sure-volume curve of the lung (PV curve) [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Measurement of Airways Closing Pressure in Man

Al-Bazzaz¹

1981

Respiration

View full text Add to dashboard Cite

In 7 healthy males, lung static and quasi-static pressure-volume (QS-PV) curves were measured simultaneously with closing volume by the single breath N₂ washout test. Comparison was made of four methods for estimation of the closing pressure (CP) at the onset of phase IV. In the first method the transpulmonary pressure (PL) that directly coincided on the tracing with onset of phase IV was measured, results varied widely with a mean of -1.3 ± 2.2 cm H₂O (x ± SD). The second method was to identify on the QS-PV curve the point of transition in the shape of the curve from concavity to convexity. This method yielded a mean CP of 2.8 ± 1.7 cm H₂O, but did not correlate statistically with closing capacity (r = 0.07, p > 0.05). The third method was to treat the whole PV curve as an exponential curve, and mathematically extrapolate the curve to a volume corresponding to the onset of phase IV, and calculate PL at this point. This method yielded CP of 2.1 ± 0.76 cm H₂O. When the same method was applied to static PV curve, CP was 2.0 ± 0.7 cm H₂O. Conformity of CP values obtained using extrapolation methods to those expected from theoretical considerations and from in vitro measurements suggests that the extrapolation methods most likely yield the true PL at the onset of airway closure

show abstract

Transpulmonary pressure gradient and ventilation distribution in excised lungs

Cited by 54 publications

References 9 publications

Effects of mechanical ventilation at low lung volume on respiratory mechanics and nitric oxide exhalation in normal rabbits

Effects of mechanical ventilation at low lung volume on respiratory mechanics and nitric oxide exhalation in normal rabbits

Prone position improves expiratory airway mechanics in severe chronic bronchitis

Measurement of Airways Closing Pressure in Man

Contact Info

Product

Resources

About