Oxygenator Addition Instead of Oxygenator Replacement

Introduction

Occasionally, a situation occurs that requires the need to replace an oxygenator during an open-heart procedure. Membrane oxygenator failures, though fortunately rare, can still happen. This report describes an alternative approach to a potentially dangerous and frustrating experience of dealing with a failing membrane oxygenator.

Case Report

A 61-year-old male, 180 cm and 86 kg., BSA 2.07m2 had been transferred from another hospital after a failed coronary artery bypass. He was supported with an ABIOMED left ventricular assist device. The patient was evaluated for heart transplant and it was decided to switch him to a more long-term assist device, i.e. TCI – HEARTMATE. The procedure was accomplished without difficulty and the patient was separated from Cardiopulmonary Bypass (CPB) in the normal fashion. The tables lines were handed off and the volume still contained in the bypass circuit, including the contents of the arterial filter, was emptied into the cell saver and processed for re-infusion of red cells to the patient.
The right ventricle began to fail dramatically and CPB had to be re-instituted on an emergent basis. A new table pack was connected, primed and handed up to the operating field. The emptied arterial filter was clamped out and the bypass line was used. CPB was instituted, and it was decided to remain on warm CPB to re-perfuse the heart. Since, the original oxygenator was still in the pump circuit and re-wetted, the efficiency of the unit was suspect and was watched closely for signs of failure. After several arterial blood gases were performed and the inability of the oxygenator to perform satisfactorily was established, the FiO2 was increased to 100% and the sweep gas flow increased to approximately 12 Liters/min. in an attempt to compensate. Additionally, venous gases were taken to insure that lack of anesthesia management was not a contributing factor. The re-circulation line was partially opened, in an attempt to increase the arterial pO2. The anesthesiologist was asked to ventilate the patient, unfortunately, with the heart unloaded, and in the presence of right heart failure, very little blood was being pumped to the lungs to assist in oxygenation or CO2 removal.

Several members of the perfusion staff put forth several ideas, including the traditional procedure of changing an oxygenator. Based on the circumstances, it was decided not to re-cool the patient and come off CPB to accomplish our goal. Rather, to place a new oxygenator in the position of the unused arterial filter. The inlet and outlet of the arterial filter were disconnected and the new oxygenator was connected in its place. Priming and de-airing were accomplished by slowly allowing volume from the circuit to fill the new oxygenator through the inlet connection. Re-circulation was performed by connecting a 3@ piece of tubing between the oxygenator and a filtered port of the cardiotomy. By having the distal end of the 2nd oxygenator in the downward position, the outlet and re-circulation port could be well de-bubbled. Once it was established that the second oxygenator was acceptable for use, the bypass line (of the original arterial filter) was clamped and the connection to the Oxygen source established. The ability to oxygenate and ventilate appropriately were almost immediately re-established. Further, confirmation was established by sending an arterial blood gas to the laboratory. The right heart recovered sufficiently with time as well as pharmacological support, and the patient was transferred to the intensive care unit.

In the face of a failing oxygenator and the traditional method of changing same, we were able to add an oxygenator to the circuit, and remain on warm CPB. Thus avoiding cooling the patient to a protective temperature and such things as: possible barbiturate coma, zero flow state and coagulopathy, etc. This may suggest an alternative method of dealing with failing or failed oxygenator.

Notes

This case occurred In April of 2000.
Although another perfusionist was the primary person, the following technique was definitely a team effort.
Given the circumstances, in retrospect we would have done some things differently. However, the basic concept was indeed sound and the outcome successful.