196 S . Pervaiz Butt et al .: J Extra Corpor Technol 2024 , 56 , 191 – 202
Figure 2 . Illustration of hybrid circuit for LTx .
In addition to ECMO support as described above , Taka et al . investigated the outcomes of lung transplant surgery using cardiopulmonary bypass ( CPB ) and a protective allograft reperfusion strategy . The results indicated that CPB , along with the protective reperfusion approach , did not result in life-threatening graft complications within the first 72 hours post-surgery . The survival rates for patients who received lungs from extended criteria donors ( ECD ) were favourable , comparable to those who received lungs from standard criteria donors ( SCD ). This suggests that using CPB with a protective reperfusion strategy does not negatively impact survival outcomes in lung transplant surgery with extended criteria donors [ 29 ].
In conclusion , ECMO serves as a crucial support system during the LTx procedure , providing temporary cardiopulmonary support .
Hybrid circuit
Some centres are implementing VA ECMO with a hybrid ECMO-CPB circuit during lung transplants . An example of this from our centre can be seen in Figure 2 .
This set up has all the benefits of a closed ECMO circuit as mentioned previously , but in addition , using the circuit without the venous reservoir reduces the priming volume and haemodilution , thus limiting the need for perioperative transfusions . In addition , the inflammatory response is reduced as a result of less artificial surface interacting with the patient ’ s blood , and there is less blood-air interface due to the lack of a reservoir . The benefit of this has been extensively studied where in full CPB , the inflammatory response seen is higher with release of cytokines IL-1b , IL-6 , IL-8 , and TNF-a with vasodilating properties , through the expression of nitric oxide ( NO ) synthase . This results in a decrease in vascular resistance and higher usage of vasopressors . A lower heparin dose is also possible with the ECMO circuit , especially if the circuit used is heparin-coated . The overall benefit of using ECMO is reduced organ damage and post-operative complications [ 33 – 37 ].
If the need however arises that full CPB is needed due to excessive bleeding , or haemodynamic instability , the circuit can easily be transitioned by clamping out the ECMO bypass loop and diverting blood through the reservoir . Pump suckers and vacuum assist can also be used in this setting and the circuit is fully set up in case the heart needs to be operated on and there is a need for cardioplegia .
The circuit components itself are a centrifugal pump which has been shown to be beneficial in prolonged cases [ 38 ] andin this case , a polymethylpentene ( PMP ) oxygenator , which has the added benefit of being able to be incorporated in the ECMO circuit postoperatively if needed .
During the surgery in our centre , ACT levels are kept above 200 seconds when using the hybrid ECMO circuit . Volume and systemic vascular resistance are managed by the anaesthetist to maintain the preload and afterload of the patient and thus helping maintain the full flows of the closed system . Postoperative support
Primary graft dysfunction ( PGD ) is a severe complication following LTx that can lead to respiratory failure within the first 72 hours . In such critical cases , ECMO plays a crucial role in providing temporary respiratory and circulatory support . By reducing strain on the graft and allowing the damaged lungs to rest and heal , ECMO increases the chances of graft recovery . It also serves as a valuable tool for assessing the viability of the transplanted lung and making informed decisions on