Cellular and acellular ex vivo lung perfusion preserve functional lung ultrastructure in a large animal model: a stereological study

Table 2 Estimated perfusion of the interalveolar septum in physiological conditions and in EVLP

	Physiological^a	aEVLP	cEVLP
Blood/perfusate pressures
PAP [kPa]	1.13^b	1.27^c	1.89^c
Capillary pressure [kPa]^d	0.75	0.78	1.10
LA pressure [kPa]	0.38^b	0.30^c	0.30^c
Alveolar air pressures
Inspiratory pressure/ Plateau airway pressure [kPa]	− 0.10^e	1.26^c	1.24^c
Expiratory pressure/ PEEP [kPa]	0.10^e	0.50^c	0.50^c
Blood/perfusate - alveolar air pressure difference
Inspiration/inflation: Capillary pressure - Inspiratory pressure/ Plateau airway pressure [kPa]	0.85	−0.48	−0.14
Expiration/deflation: Capillary pressure - Expiratory pressure/ PEEP [kPa}	0.65	0.28	0.60

Perfusion of the interalveolar septum depends on blood/perfusate pressure in septal capillaries and alveolar air pressure. When capillary pressure exceeds alveolar air pressure (positive difference) septal capillaries can be perfused. When the difference is negative, capillaries will be compressed and perfusion cannot be sustained
^aPressures and pressure relationships in a physiological in vivo situation (spontaneous breathing, closed thorax); ^bFrom Ochs and O’Brodovich [42]; ^cFrom Becker et al. [15], after 12 h EVLP; ^dLung capillary pressures are approximately halfway between pulmonary arterial and pulmonary venous pressures [42]; ^e from Kunzelmann and Thews [49]. PAP mean pulmonary artery pressure, LA left atrium, PEEP positive end-expiratory pressure

ISSN: 1465-993X