Animal models of ex vivo lung perfusion as a platform for transplantation research

Table 1 Dependent and independent variables with ex vivo lung perfusion

Dependent variables(i.e., what can be measuredwith ex vivo lung perfusion)	Independent variables(i.e., what can be varied in an ex vivo lung perfusion)
Tracheal pressure	Tracheal pressure
End expiratory pressure	End expiratory pressure
End inspiratory pressure	End inspiratory pressure
Tidal volume	Tidal volume
Compliance	Respiratory rate
Respiratory rate	Pulmonary artery flow rate
Pulmonary artery flow rate	Pulmonary artery pressure
Pulmonary artery pressure	Left atrial outflow pressure
Left atrial outflow pressure	Perfusate
Pulmonary vascular resistance	Ischemic time
Lung weight	Temperature of perfusate
Wet to dry ratio	Temperature of organ
Pre-organ pO2	Inspired gas concentration and components
Post-organ pO2
Oxygen production
Perfusate pH
Perfusate pCO2
Perfusate for molecular analysis
Tissue for mRNA, protein, or histologic analysis

Table 2 Physiologic ex vivo lung perfusion parameters

	Rat	Pig
Tidal volume	4-10 mL/kg	6-8 mL/kg
Positive end expiratory pressure	2-6 cm H2O	5 cm H2O
Flow rate	5-30 mL/min (estimated cardiac output: 25-50 mL/min per 100 g)	40% cardiac output/min (estimated cardiac output: 100 mL/min per kilogram)
Pulmonary artery pressure	13.6 cm H2O	10-15 mmHg
Perfusate albumin concentration	2%-4%	5%-7%