TABLE 1.

Trans-endothelial and trans-epithelial Starling pressure gradients at end-expiration (functional residual capacity, FRC) and end-inspiration under physiological conditions (referring to Point A in Figure 4).

	Trans-endothelial			Trans-epithelial
	End-expiration	End-inspiration		End-expiration	End-inspiration
Pcap*	9	9	Pint**	−10	−24
Pint**	−10	−24	Pliq alv#	∼ 0	∼ 0
σ end##	0.85	0.85	σ epi##	0.85	0.85
Πcap**	26.8	26.8	Πint**	13.8	13.8
Πint**	13.8	13.8	Πliq alv	0	0
			γ	1	1
ΔP	19	33	ΔP	−10	−24
σ⋅ΔΠ	−11.0	−11.0	σ⋅ΔΠ	−11.7	−11.7
Starling gradient	8.0	22.0	Starling gradient	−21.7	−35.7

Table reports the expected values for capillary, interstitial and alveolar liquid hydraulic pressure (Pcap, Pint and Pliq alv, respectively) as well as for capillary, interstitial and alveolar liquid oncotic pressure (Πcap, Πint and Πliq alv, respectively). Endothelial (σ endo) and epithelial (σ epi) protein reflection coefficients are also reported. In bold, hydraulic (ΔP) and oncotic (σΠP) pressure gradients and total Starling pressure gradient. Positive values of the Starling gradient at endothelial level indicate filtration into interstitium; negative value at epithelial level indicate alveolar reabsorption.

Pressure values are expressed in cmH₂O; σ is a pure number. *From Hakim et al., 1993; **from Miserocchi et al., 1993; ^#calculated from Beck and Lai-Fook, 1983; ^##from Parker et al., 2006. Surface tension γ = 1 dyne/cm.