Impact of Left Heart Bypass on Arterial Oxygenation During One-Lung Ventilation for Thoracic Aortic Surgery.

OBJECTIVE: The aim of this study was to reveal the mechanism of improved arterial oxygenation by measuring the changes in oxygenation before and after initiation of left heart bypass (LHB) during one-lung ventilation (OLV) for thoracic aortic surgery. DESIGN: Prospective, observational study. SETTING: Single-institution, private hospital. PARTICIPANTS: The study comprised 50 patients who underwent aortic surgery via a left thoracotomy approach with LHB circulatory support. INTERVENTIONS: Patients were ventilated using pure oxygen during OLV, and the ventilator setting was left unchanged during the measurement period. MEASUREMENTS AND MAIN RESULTS: The measurement of partial pressure of arterial oxygen (PaO2) was made at the following 4 time points: 2 minutes after heparin infusion (point 1 [P1]), 2 minutes after inflow cannula insertion through the left pulmonary vein (P2), immediately before LHB initiation (P3), and 10 minutes after LHB initiation (P4). The mean±standard deviation (mmHg) of PaO2 measurements at the P1, P2, P3, and P4 time points were 244±121, 250±123, 419±122, and 430±109, respectively, with significant increases between P1 and P3, P1 and P4, P2 and P3, and P2 and P4 (p<0.0001, respectively). No significant increase in PaO2 was seen between P1 and P2 or between P3 and P4. CONCLUSIONS: The improved arterial oxygenation during OLV in patients who underwent thoracic aortic surgery using LHB can be attributed to the insertion of an inflow cannula via the left pulmonary vein into the left atrium before LHB.

An insight into short- and long-term mechanical circulatory support systems.

Cardiogenic shock due to acute myocardial infarction, postcardiotomy syndrome following cardiac surgery, or manifestation of heart failure remains a clinical challenge with high mortality rates, despite ongoing advances in surgical techniques, widespread use of primary percutaneous interventions, and medical treatment. Clinicians have, therefore, turned to mechanical means of circulatory support. At present, a broad range of devices are available, which may be extracorporeal, implantable, or percutaneous; temporary or long term. Although counter pulsation provided by intra-aortic balloon pump (IABP) and comprehensive mechanical support for both the systemic and the pulmonary circulation through extracorporeal membrane oxygenation (ECMO) remain a major tool of acute care in patients with cardiogenic shock, both before and after surgical or percutaneous intervention, the development of devices such as the Impella or the Tandemheart allows less invasive forms of temporary support. On the other hand, concerning mid-, or long-term support, left ventricular assist devices have evolved from a last resort life-saving therapy to a well-established viable alternative for thousands of heart failure patients caused by the shortage of donor organs available for transplantation. The optimal selection of the assist device is based on the initial consideration according to hemodynamic situation, comorbidities, intended time of use and therapeutic options. The present article offers an update on currently available mechanical circulatory support systems (MCSS) for short and long-term use as well as an insight into future perspectives.