Introduction: Focused cardiac ultrasound (FoCUS) can potentially identify reversible causes of cardiac arrest during advanced cardiovascular life support (ACLS), but data on the timing of image acquisition are lacking.
Aim: To compare the quality of FoCUS images obtained during either rhythm analysis, bag-mask ventilation, or chest compression.
Methods: Adult patients in cardiac arrest were prospectively included at a Danish community hospital from Feb. 2015 to Dec. 2016. Anesthesiologists trained in FoCUS obtained subcostal images during rhythm analysis, bag-mask ventilation, and chest compression. Images were assessed by the anesthesiologists who obtained them, and by two blinded echocardiography experts. Images quality was rated as either useful for interpretation or not. An image was useful for interpretation if all the following characteristics could be determined: 1) right ventricle larger than left 2) pericardial fluid 3) collapsing ventricles. Logistic regression was used to compare proportions of images useful for interpretation.
Results: Images were obtained from 60 of 104 patients undergoing ACLS. Based on assessment by the echocardiography experts, a higher proportion of the images obtained during rhythm analyses and bag-mask ventilation were useful for interpretation, when compared with chest compression (rhythm analysis vs. chest compression: OR 2.2 (95%CI 1.3-3.8), P=0.005; ventilation vs. chest compression: OR 2.0 (95%CI 1.1-3.7), P=0.03). There was no difference between images obtained during rhythm analysis and bag-mask ventilation (OR 1.1 (95%CI 0.6-2.0), P=0.74). Based on assessment by the echocardiography experts, at least one image useful for interpretation was obtained in 72% of patients. Based on assessment by the anesthesiologists, at least one image useful for interpretation was obtained in 60% of patients.
Conclusion: The quality of FoCUS images obtained during rhythm analysis and bag-mask ventilation is superior to that of images obtained during chest compression. However, there is no difference in the quality of images obtained during rhythm analysis and bag-mask ventilation. Thus, FoCUS during bag-mask ventilation may constitute an overlooked opportunity for image acquisition during ACLS.