scholarly journals Sputum processing by mechanical dissociation: A rapid alternative to traditional sputum assessment approaches

2021 ◽  
Author(s):  
Clair Barber ◽  
Laurie Lau ◽  
Jonathan A. Ward ◽  
Thomas Daniels ◽  
Alastair Watson ◽  
...  
Keyword(s):  
Mechanical Dissociation

Abstract 439: Using the Time Interval Between R-Wave Detection and Maximum Compression Pressure to Target and Validate Delivery of Synchronized Chest Compressions During Pseudo Electro-Mechanical Dissociation

Circulation ◽  
2019 ◽  
Vol 140 (Suppl_2) ◽  
Author(s):  
Joshua W Lampe ◽  
Jeff R Gould ◽  
Karen L Moodie ◽  
Zachary P Soucy ◽  
Peter S Burrage ◽  
...  
Keyword(s):  
Blood Flow ◽  
Time Interval ◽  
Hemodynamic Parameters ◽  
Chest Compressions ◽  
Compression Pressure ◽  
Carotid Blood Flow ◽  
Maximum Compression ◽  
Local Maxima ◽  
Blood Flows ◽  
Mechanical Dissociation

Introduction: The treatment of pseudo electro-mechanical dissociation (P-EMD) with standard chest compressions leads to some compressions that interfere with blood flow created by ventricular contraction and others that are synergistic. We have previously reported that the hemodynamics generated by standard chest compressions (StdCPR) depended on the time interval between the R-wave and the maximum compression pressure (t_int). Our goal was to use the t_int to identify the optimal timing for compression synchronization and to validate the delivery of synchronized chest compressions. Methods: Eight animals underwent surgical preparation and were exposed to hypoxia to induce P-EMD. The treatment period was divided into eight 45 sec epochs during which the P-EMD was left untreated or was treated with StdCPR or chest compressions synchronized to the R-wave in the ECG (SyncCPR). For each heart beat t_int was calculated as t peak AOP - t Rwave , blood pressures were averaged, and blood flows were integrated. 1,598 chest compressions were analyzed. The location of local extrema in hemodynamic parameters as a function of positive t_int values were identified recursively by dividing the range of t_int values into increasing numbers of bins and determining which bin had the highest mean value. Results: Blood flows and pressures exhibited a non-linear dependence on t_int. The maximum CPP occurred at t_int = 90 ±2.3 ms. The maximum aortic pressure occurred at t_int = 70 ±2.3 ms. The minimum right atrial pressure occurred at t_int = 280 ±2.3 ms. The maximum carotid blood flow occurred at t_int = 100 ±2.3 ms. The maximum jugular blood flow occurred at t_int = 400 ±2.3 ms. Unsynchronized chest compressions resulted in a t_int of -21 ± 170 ms. Synchronized chest compressions resulted in a t_int of 119 ± 13 ms. Conclusions: Local maxima and minima during StdCPR were identified in several hemodynamic parameters, but the extrema were not perfectly co-located. It appears that a t_int of 90-100 ms could be optimal. SyncCPR were delivered at 119 ms, which is not far from the local maxima observed for CPP and carotid blood flow.

Mechanical dissociation of the M-band titin/obscurin complex is directionally dependent

FEBS Letters ◽  
2015 ◽  
Vol 589 (15) ◽  
pp. 1735-1739 ◽  
Author(s):  
Tracy A. Caldwell ◽  
Isaiah Sumner ◽  
Nathan T. Wright
Keyword(s):  
Mechanical Dissociation

Electro-mechanical dissociation in the heart in patients with cirrhosis

2001 ◽  
Vol 34 ◽  
pp. 67 ◽  
Author(s):  
S. Moeller ◽  
S. Fuglsang ◽  
F. Bendtsen ◽  
J.H. Henriksen
Keyword(s):  
Mechanical Dissociation

Abstract 438: Synchronization of Chest Compressions During Pseudo Electro-Mechanical Dissociation Improves Blood Pressures Relative to Standard Chest Compressions

Circulation ◽  
2019 ◽  
Vol 140 (Suppl_2) ◽  
Author(s):  
Joshua W Lampe ◽  
Jeff R Gould ◽  
Karen L Moodie ◽  
Zachary P Soucy ◽  
Peter S Burrage ◽  
...  
Keyword(s):  
Heart Beat ◽  
Rate Of Change ◽  
Atrial Pressure ◽  
Right Atrial ◽  
Right Atrial Pressure ◽  
Chest Compressions ◽  
Meaningful Improvement ◽  
Mechanical Dissociation ◽  
Blood Pressures ◽  
Over Time

Introduction: The treatment of pseudo electro-mechanical dissociation (P-EMD) with standard chest compressions leads to periods where the chest compressions and heart-beat are in phase and periods where the chest compression and heart-beat are out of phase. We hypothesized that synchronized chest compressions will improve hemodynamics relative to standardized chest compressions during P-EMD. Methods: Eight animals underwent surgical preparation and were exposed to hypoxia to induce P-EMD. The treatment period was divided into eight 45 sec epochs during which the P-EMD was left untreated or was treated with standard chest compressions or chest compressions synchronized to the R-wave in the ECG. For each epoch of CPR in each animal, we measured the rate of change in the hemodynamics over the last half of the epoch using linear regression. ANOVA modeling was used to compare changes in hemodynamics as a function of treatment. Results: The rate of change in coronary perfusion pressure (CPP), minimum right atrial pressure (RAPmin), and maximum right atrial pressure (RAPmax) was larger during synchronized compressions than during standard compressions or untreated P-EMD. The rate of change in AOPmin was larger during both treatments than during untreated P-EMD. Other differences in the rate of change were not detected between standard chest compressions and untreated P-EMD. Numerical results are shown in the table below. RAPmax decreased over time, while the other measures increased. Conclusions: Synchronized chest compressions improved several blood pressure metrics over time during P-EMD, while standardized chest compressions only improved AOPmin. While some of the changes are modest, they were sustained over 20 seconds, suggesting that continued delivery of synchronized chest compressions could result in clinically meaningful improvement in blood pressures. Table 1. ANOVA comparison of blood pressures as a function of treatment

Abstract 240: Comparison of Hemodynamics Generated by Synchronized and Interposed Compressions During Treatment of Pseudo Electro-mechanical Dissociation

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_4) ◽  
Author(s):  
Joshua W Lampe ◽  
Jill K Badin ◽  
Lyra Clark ◽  
Jeff R Gould ◽  
Karen L Moodie ◽  
...  
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Chest Compression ◽  
Right Atrial ◽  
Compression Rate ◽  
Chest Compressions ◽  
Blood Flows ◽  
Mechanical Dissociation ◽  
Life Threatening ◽  
Integrated Or

Introduction: Pseudo electro-mechanical dissociation (P-EMD) is a cardiac arrest variant characterized by a life-threatening reduction in cardiac output in the presence of organized electrical activity. Synchronization of chest compressions to the R-wave in the ECG may be preferable to the delivery of standard CPR. However, in the bradycardic P-EMD state, synchronization may result in inadequate blood flow due to the low compression/heart rate. This pilot study examined the hemodynamic effect of interposing additional chest compressions between synchronized chest compressions during bradycardic P-EMD to increase the compression rate. Methods: P-EMD was induced via hypoxia in three female swine (~30 kg) and treated with synchronized compressions until the onset of asystole (HR<12 BPM). Interposed compressions were added when the heart rate fell below 60 BPM. A chest compression was classified as synchronized or interposed depending on the presence or absence of a co-incident R-wave. Hemodynamic parameters were integrated or averaged over each compression interval. Results: Synchronized compressions tended to produce larger aortic pressures, larger carotid blood flows, and lower right atrial pressures than interposed compressions. Data from one experiment are shown in Figure 1. The relative hemodynamic benefit of a synchronized chest compression appears to depend on the effectiveness of the underlying heart contraction. The interposed chest compressions generated forward carotid blood flow and increased the compression rate during bradycardia. Discussion: During bradycardic P-EMD, synchronized compressions may generate better hemodynamics than interposed compressions, and the combination of synchronized and interposed compressions may result in more blood flow than the delivery of synchronized compressions alone. Figure 1. Comparison of hemodynamics generated by synchronized compressions (blue) and interposed compressions (red).

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