Experimental Safety And Efficacy Evaluation Of An Extracorporeal Pumpless Artificial Lung In Providing Respiratory Support Via The Axillary Vessels
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Objective: Test the safety and feasibility of implanting the pumpless, extracorporeal artificial lung (PEAL, Novalung® GmbH, Hechingen, Germany, ) in the axillary vessels and its capability to provide respiratory support during apneic ventilation in adults pigs.
Methods: Ten pigs were managed initially (4hrs) with an aggressive ventilator protocol (4hrs) (minute volume 527±62 mL, PEEP 5.1±0.3 mm Hg, peak inspiratory pressure 21.5±2.8 mm Hg, respiratory rate 21.9±2.8 breaths/min and FiO2 1.0) followed by near apneic ventilation (tidal volume 98±15 mL, PEEP 20±2mm Hg, peak inspiratory pressure 22.3±2.4 mHg, respiratory rate 4±0.3 breaths/min and FiO2 1.0) under PEAL support (4 hrs) attached to the right axillary and vein either through a direct cannulation (n=5) or end-to-side anastomoses (n=5) via 8-mm ringed polytetrafluoroethylene grafts. Bronchoalveolar lavages were hourly determined to monitor lung cytokines (IL-1β, TNF-α and PCR) and leukocytes. Hemodynamic and intrathoracic volumes variables were continuously monitored.
Results:Blood flow through the PEAL was 1.7± 0.4 L/min, which represented 30± 14% of the cardiac output (7.2±2.6 L/min), and the pressure gradient across it was 10±2 mm Hg. After implantation, PEAL induced hemodynamic modifications (Table) requiring transient vasoactive support.
Hemodynamic data| VARIABLES | AGGRESSIVE VENTITALTION | PEAL | p-value |
| Cardiac output (L/min) | 7.2±3 | 8.1±3 | N S |
Pulmonary vascular resistance
(dynes/s/cm-5) | 153.8±148 | 207.3±80.2 | NS |
| Mean pulmonary artery pressure (mm Hg) | 98.1±18 | 78.7±11.5 | <0.001 |
| Pulmonary artery wedge pressure (mm Hg) | 19.8±4.1 | 23.3±4.2 | 0.002 |
| Extravascular lung water (ml/Kg) | 10.8±5.5 | 13.3±6.4 | NS |
| Central venous pressure (mm Hg) | 18.6±3.4 | 23.1±4.9 | <0.001 |
Systemic vascular resistance
(dynes/s/cm-5) | 1013.1±356.3 | 690.1±407.2 | <0.004 |
| NS=not significant |
During PEAL, the mean O2 transfer was 225.7±70 cc/min, PaO2/FiO2 ratio 323.6±126, and CO2 removal 110±4 mL/min, without needing modification of the apneic ventilatory settings or triggering hypercapnia. There were no coagulation disorders, and no gas exchange or other significant differences between the type of vascular access. The significantly increased IL-1β and TNF-α during the aggressive ventilation period recovered within normal values during lung rest (p<0.05 ).
Conclusions: This experimental study demonstrates the feasibility of providing efficient gas exchange in a model of extracorporeal (axillary) and pumpless respiratory support during apneic ventilation, suggesting its potential ambulatory clinical application.
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