Exposure to severe hyperoxemia worsens survival and neurological outcome in patients supported by veno-arterial extracorporeal membrane oxygenation: A meta-analysis.

BACKGROUND: Veno-arterial Extracorporeal Membrane Oxygenation (VA-ECMO) is a rescue treatment in refractory cardiogenic shock (CS) or refractory cardiac arrest (CA). Exposure to hyperoxemia is common during VA-ECMO, and its impact on patient's outcome remains unclear. METHODS: We conducted a systematic review (PubMed and Scopus) and meta-analysis investigating the effects of exposure to severe hyperoxemia on mortality and poor neurological outcome in patients supported by VA-ECMO. When both adjusted and unadjusted Odds Ratio (OR) were provided, we used the adjusted one. Results are reported as OR and 95% confidence interval (CI). Subgroup analyses were conducted according to VA-ECMO indication and hyperoxemia thresholds. RESULTS: Data from 10 observational studies were included. Nine studies reported data on mortality (n = 5 refractory CA, n = 4 CS), and 4 on neurological outcome. As compared to normal oxygenation levels, exposure to severe hyperoxemia was associated with higher mortality (nine studies; OR: 1.80 [1.16-2.78]; p = 0.009; I2 = 83%; low certainty of evidence) and worse neurological outcome (four studies; OR: 1.97 [1.30-2.96]; p = 0.001; I2 = 0%; low certainty of evidence). Magnitude and effect of these findings remained valid in subgroup analyses conducted according to different hyperoxemia thresholds (>200 or >300 mmHg) and VA-ECMO indication, although the association with mortality remained uncertain in the refractory CA population (p = 0.13). Analysis restricted to studies providing adjusted OR data confirmed an increased likelihood of poorer neurological outcome (three studies; OR: 2.11 [1.32-3.38]; p = 0.002) in patients exposed to severe hyperoxemia but did not suggest higher mortality (five studies; OR: 1.68 [0.89-3.18]; p = 0.11). CONCLUSIONS: Severe hyperoxemia exposure after initiation of VA-ECMO may be associated with an almost doubled increased probability of poor neurological outcome and mortality. Clinical efforts should be made to avoid severe hyperoxemia during VA-ECMO support.

The interplay between left ventricular diastolic and right ventricular dysfunction: challenges in the interpretation of critical care echocardiography studies.

BACKGROUND: Sepsis is a leading cause of death and it is characterized not only by profound vasoplegia but also by myocardial dysfunction. Critical care echocardiography is the preferred modality for the initial assessment of the cause of shock. Moreover, it can be extremely helpful in the identification of progressing myocardial dysfunction during the course of sepsis, also known as septic cardiomyopathy. MAIN BODY: One of the issues in the identification of septic cardiomyopathy is that it can be manifest with different clinical phenotypes, from overt biventricular dysfunction to isolated left ventricular (LV) systolic and/or diastolic dysfunction, from right ventricular (RV) systolic dysfunction to RV failure and dilatation. However, the commonly used echocardiography parameters for the assessment of LV and/or RV function are not always entirely reliable. Indeed, these are influenced by variable preload and afterload conditions imposed by critical illness such as fluid shifts, sedation level and mechanical ventilation with positive pressure. CONCLUSIONS: Strain echocardiography is a promising tool for the early identification of myocardial dysfunction in the context of sepsis. Studies reporting data on strain echocardiography should be particularly detailed in order to increase the reproducibility of results and to favor comparison with future studies.